Climate influence on Baltic cod, sprat, and herring stock-recruitment relationships

NASA Astrophysics Data System (ADS)

Margonski, Piotr; Hansson, Sture; Tomczak, Maciej T.; Grzebielec, Ryszard

2010-10-01

A wide range of possible recruitment drivers were tested for key exploited fish species in the Baltic Sea Regional Advisory Council (RAC) area: Eastern Baltic Cod, Central Baltic Herring, Gulf of Riga Herring, and sprat. For each of the stocks, two hypotheses were tested: (i) recruitment is significantly related to spawning stock biomass, climatic forcing, and feeding conditions and (ii) by acknowledging these drivers, management decisions can be improved. Climate impact expressed by climatic indices or changes in water temperature was included in all the final models. Recruitment of the herring stock appeared to be influenced by different factors: the spawning stock biomass, winter Baltic Sea Index prior to spawning, and potentially the November-December sea surface temperature during the winter after spawning were important to Gulf of Riga Herring, while the final models for Central Baltic Herring included spawning stock biomass and August sea surface temperature. Recruitment of sprat appeared to be influenced by July-August temperature, but was independent of the spawning biomass when SSB > 200,000 tons. Recruitment of Eastern Baltic Cod was significantly related to spawning stock biomass, the winter North Atlantic Oscillation index, and the reproductive volume in the Gotland Basin in May. All the models including extrinsic factors significantly improved prediction ability as compared to traditional models, which account for impacts of the spawning stock biomass alone. Based on the final models the minimum spawning stock biomass to derive the associated minimum recruitment under average environmental conditions was calculated for each stock. Using uncertainty analyses, the spawning stock biomass required to produce associated minimum recruitment was presented with different probabilities considering the influence of the extrinsic drivers. This tool allows for recruitment to be predicted with a required probability, that is, higher than the average 50% estimated from the models. Further, this approach considers unfavorable environmental conditions which mean that a higher spawning stock biomass is needed to maintain recruitment at a required level.

Effects of gill-net fishing on marine birds in a biological hotspot in the northwest Atlantic.

PubMed

Davoren, Gail K

2007-08-01

Marine biological hotspots, or areas where high abundances of species overlap in space and time, are ecologically important areas because energy flow through marine food webs, a key ecosystem process, is maximized in these areas. I investigated whether top predators aggregated at persistent spawning sites of a key forage fish species, capelin (Mallotus villosus), on the NE coast of Newfoundland during July and August 2000-2003. By examining the distributional patterns of top predators through ship-based surveys at multiple spatial and temporal scales, I found that the biomasses of birds-dominated by Common Murres (Uria aalge)-and mammals-dominated by whale species-were concentrated along the coast, with a biological hotspot forming near two persistent spawning sites of capelin in all years. The formation of this hotspot was well defined in space and time from middle of July to middle of August, likely coinciding with the spawning chronology of capelin. Within this hotspot, there was a high spatial and temporal overlap of Common Murres and gill nets set to capture Atlantic cod (Gadus morhua). This resulted in breeding murres becoming entangled in gill nets while feeding on spawning capelin. Despite an acknowledged uncertainty of bycatch mortality, estimates for the larger regional-scale area (1936-4973 murres/year; 0.2-0.6% of the breeding population) underestimated mortality relative to estimates within the hotspot (3053-14054 murres/year; 0.4-1.7%). Although fishing effort for Atlantic cod has declined substantially since the groundfish moratorium in 1992, chronic, unnatural, and additive mortality through bycatch continues in coastal Newfoundland. Restricted use of gill nets within this and other biological hotspots during the capelin spawning period appears to be a straightforward application of the "ecological and biologically significant area" management framework in Canada's Oceans Act. This protection would minimize murre bycatch and maintain ecosystem integrity.

Effects of climate change on the survival of larval cod

NASA Astrophysics Data System (ADS)

Kristiansen, T.; Stock, C. A.; Drinkwater, K. F.; Curchitser, E. N.

2011-12-01

Understanding how climate change may impact important commercial fisheries is critical for developing sustainable fisheries management strategies. In this study, we used simulations from an Earth System Model (NOAA GFDL ESM2.1) coupled with an individual-based model (IBM) for larval fish to provide a first assessment of the potential importance of climate-change driven changes in primary productivity and temperature on cod recruitment in the North Atlantic to the year 2100. ESM model output was averaged for 5 regions, each with an area of 5x5 on a latitude-longitude grid, and representing the geographic boundaries of the current cod range. The physical and environmental data were incorporated into a mechanistic IBM used to simulate the critical early phases in the life of larval fish (e.g. cod) in a changing environment. Large phytoplankton production was predicted to decrease in most regions, thereby lowering the number of meso-zooplankton in the water column. Meso-zooplankton is the most important prey item for larval cod and a reduction in their numbers have strong impacts on larval cod survival. The combination of lowered prey abundance with increased energy requirement for growth and metabolism through increased temperature had a negative impact on cod recruitment in all modeled regions of the North Atlantic. The probability of survival past the larval stages was reduced with 20-30% at all five spawning grounds by the year 2100. Together, these results suggest climate change could have significant impacts on the survival of larval cod in the North Atlantic.

Chapter 3. Effects of climate change and commercial fishing on Atlantic cod Gadus morhua.

PubMed

Mieszkowska, Nova; Genner, Martin J; Hawkins, Stephen J; Sims, David W

2009-01-01

During the course of the last century, populations of Atlantic cod Gadus morhua L. have undergone dramatic declines in abundance across their biogeographic range, leading to debate about the relative roles of climatic warming and overfishing in driving these changes. In this chapter, we describe the geographic distributions of this important predator of North Atlantic ecosystems and document extensive evidence for limitations of spatial movement and local adaptation from population genetic markers and electronic tagging. Taken together, this evidence demonstrates that knowledge of spatial population ecology is critical for evaluating the effects of climate change and commercial harvesting. To explore the possible effects of climate change on cod, we first describe thermal influences on individual physiology, growth, activity and maturation. We then evaluate evidence that temperature has influenced population-level processes including direct effects on recruitment through enhanced growth and activity, and indirect effects through changes to larval food resources. Although thermal regimes clearly define the biogeographic range of the species, and strongly influence many aspects of cod biology, the evidence that population declines across the North Atlantic are strongly linked to fishing activity is now overwhelming. Although there is considerable concern about low spawning stock biomasses, high levels of fishing activity continues in many areas. Even with reduced fishing effort, the potential for recovery from low abundance may be compromised by unfavourable climate and Allee effects. Current stock assessment and management approaches are reviewed, alongside newly advocated methods for monitoring stock status and recovery. However, it remains uncertain whether the rebuilding of cod to historic population sizes and demographic structures will be possible in a warmer North Atlantic.

Large scale, synchronous variability of marine fish populations driven by commercial exploitation.

PubMed

Frank, Kenneth T; Petrie, Brian; Leggett, William C; Boyce, Daniel G

2016-07-19

Synchronous variations in the abundance of geographically distinct marine fish populations are known to occur across spatial scales on the order of 1,000 km and greater. The prevailing assumption is that this large-scale coherent variability is a response to coupled atmosphere-ocean dynamics, commonly represented by climate indexes, such as the Atlantic Multidecadal Oscillation and North Atlantic Oscillation. On the other hand, it has been suggested that exploitation might contribute to this coherent variability. This possibility has been generally ignored or dismissed on the grounds that exploitation is unlikely to operate synchronously at such large spatial scales. Our analysis of adult fishing mortality and spawning stock biomass of 22 North Atlantic cod (Gadus morhua) stocks revealed that both the temporal and spatial scales in fishing mortality and spawning stock biomass were equivalent to those of the climate drivers. From these results, we conclude that greater consideration must be given to the potential of exploitation as a driving force behind broad, coherent variability of heavily exploited fish species.

Recruitment Variability in North Atlantic Cod and Match-Mismatch Dynamics

PubMed Central

Kristiansen, Trond; Drinkwater, Kenneth F.; Lough, R. Gregory; Sundby, Svein

2011-01-01

Background Fisheries exploitation, habitat destruction, and climate are important drivers of variability in recruitment success. Understanding variability in recruitment can reveal mechanisms behind widespread decline in the abundance of key species in marine and terrestrial ecosystems. For fish populations, the match-mismatch theory hypothesizes that successful recruitment is a function of the timing and duration of larval fish abundance and prey availability. However, the underlying mechanisms of match-mismatch dynamics and the factors driving spatial differences between high and low recruitment remain poorly understood. Methodology/Principal Findings We used empirical observations of larval fish abundance, a mechanistic individual-based model, and a reanalysis of ocean temperature data from 1960 to 2002 to estimate the survival of larval cod (Gadus morhua). From the model, we quantified how survival rates changed during the warmest and coldest years at four important cod spawning sites in the North Atlantic. The modeled difference in survival probability was not large for any given month between cold or warm years. However, the cumulative effect of higher growth rates and survival through the entire spawning season in warm years was substantial with 308%, 385%, 154%, and 175% increases in survival for Georges Bank, Iceland, North Sea, and Lofoten cod stocks, respectively. We also found that the importance of match-mismatch dynamics generally increased with latitude. Conclusions/Significance Our analyses indicate that a key factor for enhancing survival is the duration of the overlap between larval and prey abundance and not the actual timing of the peak abundance. During warm years, the duration of the overlap between larval fish and their prey is prolonged due to an early onset of the spring bloom. This prolonged season enhances cumulative growth and survival, leading to a greater number of large individuals with enhanced potential for survival to recruitment. PMID:21408215

Climate-driven ichthyoplankton drift model predicts growth of top predator young.

PubMed

Myksvoll, Mari S; Erikstad, Kjell E; Barrett, Robert T; Sandvik, Hanno; Vikebø, Frode

2013-01-01

Climate variability influences seabird population dynamics in several ways including access to prey near colonies during the critical chick-rearing period. This study addresses breeding success in a Barents Sea colony of common guillemots Uria aalge where trophic conditions vary according to changes in the northward transport of warm Atlantic Water. A drift model was used to simulate interannual variations in transport of cod Gadus morhua larvae along the Norwegian coast towards their nursery grounds in the Barents Sea. The results showed that the arrival of cod larvae from southern spawning grounds had a major effect on the size of common guillemot chicks at fledging. Furthermore, the fraction of larvae from the south was positively correlated to the inflow of Atlantic Water into the Barents Sea thus clearly demonstrating the mechanisms by which climate-driven bottom-up processes influence interannual variations in reproductive success in a marine top predator.

Climate-Driven Ichthyoplankton Drift Model Predicts Growth of Top Predator Young

PubMed Central

Myksvoll, Mari S.; Erikstad, Kjell E.; Barrett, Robert T.; Sandvik, Hanno; Vikebø, Frode

2013-01-01

Climate variability influences seabird population dynamics in several ways including access to prey near colonies during the critical chick-rearing period. This study addresses breeding success in a Barents Sea colony of common guillemots Uria aalge where trophic conditions vary according to changes in the northward transport of warm Atlantic Water. A drift model was used to simulate interannual variations in transport of cod Gadus morhua larvae along the Norwegian coast towards their nursery grounds in the Barents Sea. The results showed that the arrival of cod larvae from southern spawning grounds had a major effect on the size of common guillemot chicks at fledging. Furthermore, the fraction of larvae from the south was positively correlated to the inflow of Atlantic Water into the Barents Sea thus clearly demonstrating the mechanisms by which climate-driven bottom-up processes influence interannual variations in reproductive success in a marine top predator. PMID:24265761

TaqMan DNA technology confirms likely overestimation of cod (Gadus morhua L.) egg abundance in the Irish Sea: implications for the assessment of the cod stock and mapping of spawning areas using egg-based methods.

PubMed

Fox, C J; Taylor, M I; Pereyra, R; Villasana, M I; Rico, C

2005-03-01

Recent substantial declines in northeastern Atlantic cod stocks necessitate improved biological knowledge and the development of techniques to complement standard stock assessment methods (which largely depend on accurate commercial catch data). In 2003, an ichthyoplankton survey was undertaken in the Irish Sea and subsamples of 'cod-like' eggs were analysed using a TaqMan multiplex, PCR (polymerase chain reaction) assay (with specific probes for cod, haddock and whiting). The TaqMan method was readily applied to the large number of samples (n = 2770) generated during the survey and when combined with a manual DNA extraction protocol had a low failure rate of 6%. Of the early stage 'cod-like' eggs (1.2-1.75 mm diameter) positively identified: 34% were cod, 8% haddock and 58% whiting. As previous stock estimates based on egg surveys for Irish Sea cod assumed that the majority of 'cod-like' eggs were from cod, the TaqMan results confirm that there was probably substantial contamination by eggs of whiting and haddock that would have inflated estimates of the stock biomass.

Recruitment of shrimp ( Pandalus borealis) in the Barents Sea related to spawning stock and environment

NASA Astrophysics Data System (ADS)

Aschan, Michaela; Ingvaldsen, Randi

2009-10-01

The shrimp spawn in autumn, and the females carry their eggs as out roe until spring when the larvae hatch. Within a period of 2 months the shrimp larvae settle to the bottom. It has been claimed that the year-class strength probably is determined during the larval phase. Today's assessment and forecast of the shrimp stock productivity and potential fishing yields are weak. This is partly due to poor knowledge on population dynamics from hatching until the shrimp are caught in the fishery at the age of 3 or 4 years. We, therefore, here identify the most important abiotic and biotic factors that affect recruitment in addition to spawning stock biomass. Since 1995, a net attached to the underbelly of the survey trawl used at the annual cruise in the Barents Sea has caught juvenile shrimp. The abundance of settled shrimp larvae varies in time and space. The recruitment to the fishery has been quite stable with the exception of the 1996 year-class, which was observed as 1-year-olds but has not been registered since. The temporal pattern of the three youngest year-classes is studied in relation to abiotic factors such as sea temperature, ice index and North Atlantic Oscillation, as well as biotic factors such as spawning stock biomass and presence of copepods, euphausiids and predating cod. Recruitment indices and factors identified by the Spearmann correlation to be significantly correlated with recruitment were used as input in a principal component analysis (PCA) and a generalized additive model (GAM) was applied. Abundance of 1-year-old shrimp is positively correlated to spawning stock biomass the previous year and to temperature of the previous winter, and negatively correlated with the number of 1-year-old cod. Two-year-old shrimp show significant correlation with temperature, whereas there is a strong negative correlation with euphausiids. Three-year-old shrimp are significantly correlated with the number of 2-year-old shrimp the previous year but negatively correlated to temperature at sampling time. This is probably due to less overlap with the main predator cod when cold. Ricker functions indicate an increased density-dependent mortality with age. When predicting the recruitment of shrimp to the fishery, the spawning stock biomass, the abundance of cod and euphausiids, as well as the temperature should be included.

Understanding climate impacts on recruitment and spatial dynamics of Atlantic cod in the Gulf of Maine: Integration of observations and modeling

NASA Astrophysics Data System (ADS)

Runge, Jeffrey A.; Kovach, Adrienne I.; Churchill, James H.; Kerr, Lisa A.; Morrison, John R.; Beardsley, Robert C.; Berlinsky, David L.; Chen, Changsheng; Cadrin, Steven X.; Davis, Cabell S.; Ford, Kathryn H.; Grabowski, Jonathan H.; Howell, W. Huntting; Ji, Rubao; Jones, Rebecca J.; Pershing, Andrew J.; Record, Nicholas R.; Thomas, Andrew C.; Sherwood, Graham D.; Tallack, Shelly M. L.; Townsend, David W.

2010-10-01

We put forward a combined observing and modeling strategy for evaluating effects of environmental forcing on the dynamics of spatially structured cod populations spawning in the western Gulf of Maine. Recent work indicates at least two genetically differentiated complexes in this region: a late spring spawning, coastal population centered in Ipswich Bay, and a population that spawns in winter inshore and on nearshore banks in the Gulf of Maine and off southern New England. The two populations likely differ in trophic interactions and in physiological and behavioral responses to different winter and spring environments. Coupled physical-biological modeling has advanced to the point where within-decade forecasting of environmental conditions for recruitment to each of the two populations is feasible. However, the modeling needs to be supported by hydrographic, primary production and zooplankton data collected by buoys, and by data from remote sensing and fixed station sampling. Forecasts of environmentally driven dispersal and growth of planktonic early life stages, combined with an understanding of possible population-specific predator fields, usage of coastal habitat by juveniles and adult resident and migratory patterns, can be used to develop scenarios for spatially explicit population responses to multiple forcings, including climate change, anthropogenic impacts on nearshore juvenile habitat, connectivity among populations and management interventions such as regional fisheries closures.

Spatiotemporal SNP analysis reveals pronounced biocomplexity at the northern range margin of Atlantic cod Gadus morhua

PubMed Central

Therkildsen, Nina Overgaard; Hemmer-Hansen, Jakob; Hedeholm, Rasmus Berg; Wisz, Mary S; Pampoulie, Christophe; Meldrup, Dorte; Bonanomi, Sara; Retzel, Anja; Olsen, Steffen Malskær; Nielsen, Einar Eg

2013-01-01

Accurate prediction of species distribution shifts in the face of climate change requires a sound understanding of population diversity and local adaptations. Previous modeling has suggested that global warming will lead to increased abundance of Atlantic cod (Gadus morhua) in the ocean around Greenland, but the dynamics of earlier abundance fluctuations are not well understood. We applied a retrospective spatiotemporal population genomics approach to examine the temporal stability of cod population structure in this region and to search for signatures of divergent selection over a 78-year period spanning major demographic changes. Analyzing >900 gene-associated single nucleotide polymorphisms in 847 individuals, we identified four genetically distinct groups that exhibited varying spatial distributions with considerable overlap and mixture. The genetic composition had remained stable over decades at some spawning grounds, whereas complete population replacement was evident at others. Observations of elevated differentiation in certain genomic regions are consistent with adaptive divergence between the groups, indicating that they may respond differently to environmental variation. Significantly increased temporal changes at a subset of loci also suggest that adaptation may be ongoing. These findings illustrate the power of spatiotemporal population genomics for revealing biocomplexity in both space and time and for informing future fisheries management and conservation efforts. PMID:23789034

Spatiotemporal SNP analysis reveals pronounced biocomplexity at the northern range margin of Atlantic cod Gadus morhua.

PubMed

Therkildsen, Nina Overgaard; Hemmer-Hansen, Jakob; Hedeholm, Rasmus Berg; Wisz, Mary S; Pampoulie, Christophe; Meldrup, Dorte; Bonanomi, Sara; Retzel, Anja; Olsen, Steffen Malskær; Nielsen, Einar Eg

2013-06-01

Accurate prediction of species distribution shifts in the face of climate change requires a sound understanding of population diversity and local adaptations. Previous modeling has suggested that global warming will lead to increased abundance of Atlantic cod (Gadus morhua) in the ocean around Greenland, but the dynamics of earlier abundance fluctuations are not well understood. We applied a retrospective spatiotemporal population genomics approach to examine the temporal stability of cod population structure in this region and to search for signatures of divergent selection over a 78-year period spanning major demographic changes. Analyzing >900 gene-associated single nucleotide polymorphisms in 847 individuals, we identified four genetically distinct groups that exhibited varying spatial distributions with considerable overlap and mixture. The genetic composition had remained stable over decades at some spawning grounds, whereas complete population replacement was evident at others. Observations of elevated differentiation in certain genomic regions are consistent with adaptive divergence between the groups, indicating that they may respond differently to environmental variation. Significantly increased temporal changes at a subset of loci also suggest that adaptation may be ongoing. These findings illustrate the power of spatiotemporal population genomics for revealing biocomplexity in both space and time and for informing future fisheries management and conservation efforts.

Mapping the spawning grounds of North Sea cod (Gadus morhua) by direct and indirect means.

PubMed

Fox, Clive J; Taylor, Martin; Dickey-Collas, Mark; Fossum, Petter; Kraus, Gerd; Rohlf, Norbert; Munk, Peter; van Damme, Cindy J G; Bolle, Loes J; Maxwell, David L; Wright, Peter J

2008-07-07

Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey to cover the whole North Sea. Also, this survey, conducted in 2004, was the first to make extensive use of DNA-based molecular methods to unambiguously identify early developmental stage cod eggs. We compare the findings from the plankton survey with estimated egg production inferred from the distribution of mature cod in contemporaneous trawl surveys. Results from both approaches were in general agreement and showed hot spots of egg production around the southern and eastern edges of the Dogger Bank, in the German Bight, the Moray Firth and to the east of the Shetlands. These areas broadly coincide with known spawning locations from the period 1940 to 1970. We were, however, unable to directly detect significant numbers of cod eggs at the historic spawning ground off Flamborough (northeast coast of England). The results demonstrate that most of the major spawning grounds of cod in the North Sea are still active but that some localized populations may have been reduced to the point where it is now difficult to detect the presence of eggs in the plankton.

Mapping the spawning grounds of North Sea cod (Gadus morhua) by direct and indirect means

PubMed Central

Fox, Clive J; Taylor, Martin; Dickey-Collas, Mark; Fossum, Petter; Kraus, Gerd; Rohlf, Norbert; Munk, Peter; van Damme, Cindy J.G; Bolle, Loes J; Maxwell, David L; Wright, Peter J

2008-01-01

Despite recent evidence for sub-stock structuring, North Sea cod are assessed as a single unit. As a consequence, knowledge of sub-stock trends is poor. In particular, there are no recent evaluations of which spawning grounds are active. Here we report results from the first ichthyoplankton survey to cover the whole North Sea. Also, this survey, conducted in 2004, was the first to make extensive use of DNA-based molecular methods to unambiguously identify early developmental stage cod eggs. We compare the findings from the plankton survey with estimated egg production inferred from the distribution of mature cod in contemporaneous trawl surveys. Results from both approaches were in general agreement and showed hot spots of egg production around the southern and eastern edges of the Dogger Bank, in the German Bight, the Moray Firth and to the east of the Shetlands. These areas broadly coincide with known spawning locations from the period 1940 to 1970. We were, however, unable to directly detect significant numbers of cod eggs at the historic spawning ground off Flamborough (northeast coast of England). The results demonstrate that most of the major spawning grounds of cod in the North Sea are still active but that some localized populations may have been reduced to the point where it is now difficult to detect the presence of eggs in the plankton. PMID:18397869

Climate and population density drive changes in cod body size throughout a century on the Norwegian coast

PubMed Central

Rogers, Lauren A.; Stige, Leif C.; Olsen, Esben M.; Knutsen, Halvor; Chan, Kung-Sik; Stenseth, Nils Chr.

2011-01-01

Understanding how populations respond to changes in climate requires long-term, high-quality datasets, which are rare for marine systems. We estimated the effects of climate warming on cod lengths and length variability using a unique 91-y time series of more than 100,000 individual juvenile cod lengths from surveys that began in 1919 along the Norwegian Skagerrak coast. Using linear mixed-effects models, we accounted for spatial population structure and the nested structure of the survey data to reveal opposite effects of spring and summer warming on juvenile cod lengths. Warm summer temperatures in the coastal Skagerrak have limited juvenile growth. In contrast, warmer springs have resulted in larger juvenile cod, with less variation in lengths within a cohort, possibly because of a temperature-driven contraction in the spring spawning period. A density-dependent reduction in length was evident only at the highest population densities in the time series, which have rarely been observed in the last decade. If temperatures rise because of global warming, nonlinearities in the opposing temperature effects suggest that negative effects of warmer summers will increasingly outweigh positive effects of warmer springs, and the coastal Skagerrak will become ill-suited for Atlantic cod. PMID:21245301

Variation in spawning time promotes genetic variability in population responses to environmental change in a marine fish

PubMed Central

Hutchings, Jeffrey A

2015-01-01

Abstract The level of phenotypic plasticity displayed within a population (i.e. the slope of the reaction norm) reflects the short-term response of a population to environmental change, while variation in reaction norm slopes among populations reflects spatial variation in these responses. Thus far, studies of thermal reaction norm variation have focused on geographically driven adaptation among different latitudes, altitudes or habitats. Yet, thermal variability is a function of both space and time. For organisms that reproduce at different times of year, such variation has the potential to promote adaptive variability in thermal responses for critical early life stages. Using common-garden experiments, we examined the spatial scale of genetic variation in thermal plasticity for early life-history traits among five populations of endangered Atlantic cod (Gadus morhua) that spawn at different times of year. Patterns of plasticity for larval growth and survival suggest that population responses to climate change will differ substantially, with increasing water temperatures posing a considerably greater threat to autumn-spawning cod than to those that spawn in winter or spring. Adaptation to seasonal cooling or warming experienced during the larval stage is suggested as a possible cause. Furthermore, populations that experience relatively cold temperatures during early life might be more sensitive to changes in temperature. Substantial divergence in adaptive traits was evident at a smaller spatial scale than has previously been shown for a marine fish with no apparent physical barriers to gene flow (∼200 km). Our findings highlight the need to consider the impact of intraspecific variation in reproductive timing on thermal adaptation when forecasting the effects of climate change on animal populations. PMID:27293712

Variation in spawning time promotes genetic variability in population responses to environmental change in a marine fish.

PubMed

Oomen, Rebekah A; Hutchings, Jeffrey A

2015-01-01

The level of phenotypic plasticity displayed within a population (i.e. the slope of the reaction norm) reflects the short-term response of a population to environmental change, while variation in reaction norm slopes among populations reflects spatial variation in these responses. Thus far, studies of thermal reaction norm variation have focused on geographically driven adaptation among different latitudes, altitudes or habitats. Yet, thermal variability is a function of both space and time. For organisms that reproduce at different times of year, such variation has the potential to promote adaptive variability in thermal responses for critical early life stages. Using common-garden experiments, we examined the spatial scale of genetic variation in thermal plasticity for early life-history traits among five populations of endangered Atlantic cod (Gadus morhua) that spawn at different times of year. Patterns of plasticity for larval growth and survival suggest that population responses to climate change will differ substantially, with increasing water temperatures posing a considerably greater threat to autumn-spawning cod than to those that spawn in winter or spring. Adaptation to seasonal cooling or warming experienced during the larval stage is suggested as a possible cause. Furthermore, populations that experience relatively cold temperatures during early life might be more sensitive to changes in temperature. Substantial divergence in adaptive traits was evident at a smaller spatial scale than has previously been shown for a marine fish with no apparent physical barriers to gene flow (∼200 km). Our findings highlight the need to consider the impact of intraspecific variation in reproductive timing on thermal adaptation when forecasting the effects of climate change on animal populations.

Dual Annual Spawning Races in Atlantic Sturgeon

PubMed Central

Balazik, Matthew T.; Musick, John A.

2015-01-01

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations in the United States were listed as either endangered or threatened under the Endangered Species Act in 2012. Because of the endangered/threatened status, a better understanding of Atlantic sturgeon life-history behavior and habitat use is important for effective management. It has been widely documented that Atlantic sturgeon reproduction occurs from late winter to early summer, varying clinally with latitude. However, recent data show Atlantic sturgeon also spawn later in the year. The group that spawns later in the year seems to be completely separate from the spring spawning run. Recognition of the later spawning season has drastically modified estimates of the population status of Atlantic sturgeon in Virginia. With the combination of new telemetry data and historical documentation we describe a dual spawning strategy that likely occurs in various degrees along most, if not all, of the Atlantic sturgeon's range. Using new data combined with historical sources, a new spawning strategy emerges which managers and researchers should note when determining the status of Atlantic sturgeon populations and implementing conservation measures. PMID:26020631

Genetic differentiation of spring-spawning and fall-spawning male Atlantic sturgeon in the James River, Virginia

PubMed Central

Balazik, Matthew T.; Farrae, Daniel J.; Darden, Tanya L.; Garman, Greg C.

2017-01-01

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations are currently at severely depleted levels due to historic overfishing, habitat loss, and pollution. The importance of biologically correct stock structure for effective conservation and management efforts is well known. Recent improvements in our understanding of Atlantic sturgeon migrations, movement, and the occurrence of putative dual spawning groups leads to questions regarding the true stock structure of this endangered species. In the James River, VA specifically, captures of spawning Atlantic sturgeon and accompanying telemetry data suggest there are two discrete spawning groups of Atlantic sturgeon. The two putative spawning groups were genetically evaluated using a powerful microsatellite marker suite to determine if they are genetically distinct. Specifically, this study evaluates the genetic structure, characterizes the genetic diversity, estimates effective population size, and measures inbreeding of Atlantic sturgeon in the James River. The results indicate that fall and spring spawning James River Atlantic sturgeon groups are genetically distinct (overall FST = 0.048, F’ST = 0.181) with little admixture between the groups. The observed levels of genetic diversity and effective population sizes along with the lack of detected inbreeding all indicated that the James River has two genetically healthy populations of Atlantic sturgeon. The study also demonstrates that samples from adult Atlantic sturgeon, with proper sample selection criteria, can be informative when creating reference population databases. The presence of two genetically-distinct spawning groups of Atlantic sturgeon within the James River raises concerns about the current genetic assignment used by managers. Other nearby rivers may also have dual spawning groups that either are not accounted for or are pooled in reference databases. Our results represent the second documentation of genetically distinct dual spawning groups of Atlantic sturgeon in river systems along the U.S. Atlantic coast, suggesting that current reference population database should be updated to incorporate both new samples and our increased understanding of Atlantic sturgeon life history. PMID:28686610

Development and experimental validation of a 20K Atlantic cod (Gadus morhua) oligonucleotide microarray based on a collection of over 150,000 ESTs.

PubMed

Booman, Marije; Borza, Tudor; Feng, Charles Y; Hori, Tiago S; Higgins, Brent; Culf, Adrian; Léger, Daniel; Chute, Ian C; Belkaid, Anissa; Rise, Marlies; Gamperl, A Kurt; Hubert, Sophie; Kimball, Jennifer; Ouellette, Rodney J; Johnson, Stewart C; Bowman, Sharen; Rise, Matthew L

2011-08-01

The collapse of Atlantic cod (Gadus morhua) wild populations strongly impacted the Atlantic cod fishery and led to the development of cod aquaculture. In order to improve aquaculture and broodstock quality, we need to gain knowledge of genes and pathways involved in Atlantic cod responses to pathogens and other stressors. The Atlantic Cod Genomics and Broodstock Development Project has generated over 150,000 expressed sequence tags from 42 cDNA libraries representing various tissues, developmental stages, and stimuli. We used this resource to develop an Atlantic cod oligonucleotide microarray containing 20,000 unique probes. Selection of sequences from the full range of cDNA libraries enables application of the microarray for a broad spectrum of Atlantic cod functional genomics studies. We included sequences that were highly abundant in suppression subtractive hybridization (SSH) libraries, which were enriched for transcripts responsive to pathogens or other stressors. These sequences represent genes that potentially play an important role in stress and/or immune responses, making the microarray particularly useful for studies of Atlantic cod gene expression responses to immune stimuli and other stressors. To demonstrate its value, we used the microarray to analyze the Atlantic cod spleen response to stimulation with formalin-killed, atypical Aeromonas salmonicida, resulting in a gene expression profile that indicates a strong innate immune response. These results were further validated by quantitative PCR analysis and comparison to results from previous analysis of an SSH library. This study shows that the Atlantic cod 20K oligonucleotide microarray is a valuable new tool for Atlantic cod functional genomics research.

Underwater sound from vessel traffic reduces the effective communication range in Atlantic cod and haddock.

PubMed

Stanley, Jenni A; Van Parijs, Sofie M; Hatch, Leila T

2017-11-07

Stellwagen Bank National Marine Sanctuary is located in Massachusetts Bay off the densely populated northeast coast of the United States; subsequently, the marine inhabitants of the area are exposed to elevated levels of anthropogenic underwater sound, particularly due to commercial shipping. The current study investigated the alteration of estimated effective communication spaces at three spawning locations for populations of the commercially and ecologically important fishes, Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus). Both the ambient sound pressure levels and the estimated effective vocalization radii, estimated through spherical spreading models, fluctuated dramatically during the three-month recording periods. Increases in sound pressure level appeared to be largely driven by large vessel activity, and accordingly exhibited a significant positive correlation with the number of Automatic Identification System tracked vessels at the two of the three sites. The near constant high levels of low frequency sound and consequential reduction in the communication space observed at these recording sites during times of high vocalization activity raises significant concerns that communication between conspecifics may be compromised during critical biological periods. This study takes the first steps in evaluating these animals' communication spaces and alteration of these spaces due to anthropogenic underwater sound.

Flesh quality and biochemistry of light-manipulated Atlantic cod (Gadus morhua) and the significance of collagen cross-links on fillet firmness and gaping.

PubMed

Hagen, Ørjan; Johnsen, Chris André

2016-01-01

The aim of our study was to investigate whether light-manipulation, causing accelerated or delayed maturation, could be used as a tool to improve fillet gaping score and texture of farmed cod (Gadus morhua L.) harvested during summer. Control and accelerated groups had completed spawning by the time of harvest, and expressed sexual dimorphism in various biometric and flesh quality parameters. Pyridinoline cross-links, a key biochemical parameter investigated, were positively correlated with texture (r(2) = 0.4), as also were cathepsin B&L and sex. Gaping was also impacted by pyridinoline cross-links, together with body mass and maturation. Interestingly, the level of gaping was significantly reduced with a pyridinoline cross-link concentration of >2500 pmols g(-1) dry mass. In conclusion, light-manipulation can be used as a tool to improve flesh texture of farmed cod with a low gaping score, but with compromise of increased dress out percentage for the accelerated group. Copyright © 2015 Elsevier Ltd. All rights reserved.

Seasonal distribution and abundance of fishes and decapod crustaceans in a Cape Cod estuary

USGS Publications Warehouse

Able, K.W.; Fahay, M.P.; Heck, K.L.; Roman, C.T.; Lazzari, M.A.; Kaiser, S.C.

2002-01-01

Sampling in several habitat types (sand/mud, eelgrass, sand, gravel, macroalgae/mud) during all seasons with a variety of gears in Nauset Marsh, Massachusetts during 1985-1987 found a fauna consisting of 35 fish and 10 decapod crustacean species. Although most of the abundant species were found in several habitat types, species richness and habitat use appeared to be highest for vegetated habitats (eelgrass, macroalgae). The fishes and decapods were numerically dominated by cold-water taxa; however, numerous fish species, represented by rare individuals of predominantly southern forms, enriched the fauna. Species composition of Nauset Marsh could be distinguished from estuaries south of Cape Cod and even from the south shore of the cape. Both fishes and decapods were most abundant during the summer, apparently due to the contributions from spring and summer spawning in the estuary and the adjacent Atlantic Ocean. The location of Nauset Marsh and other estuaries on Cape Cod provide a unique opportunity to evaluate the importance of this region as a faunal boundary to estuarine species.

Discovery of a spawning ground reveals diverse migration strategies in Atlantic bluefin tuna (Thunnus thynnus).

PubMed

Richardson, David E; Marancik, Katrin E; Guyon, Jeffrey R; Lutcavage, Molly E; Galuardi, Benjamin; Lam, Chi Hin; Walsh, Harvey J; Wildes, Sharon; Yates, Douglas A; Hare, Jonathan A

2016-03-22

Atlantic bluefin tuna are a symbol of both the conflict between preservationist and utilitarian views of top ocean predators, and the struggle to reach international consensus on the management of migratory species. Currently, Atlantic bluefin tuna are managed as an early-maturing eastern stock, which spawns in the Mediterranean Sea, and a late-maturing western stock, which spawns in the Gulf of Mexico. However, electronic tagging studies show that many bluefin tuna, assumed to be of a mature size, do not visit either spawning ground during the spawning season. Whether these fish are spawning in an alternate location, skip-spawning, or not spawning until an older age affects how vulnerable this species is to anthropogenic stressors including exploitation. We use larval collections to demonstrate a bluefin tuna spawning ground in the Slope Sea, between the Gulf Stream and northeast United States continental shelf. We contend that western Atlantic bluefin tuna have a differential spawning migration, with larger individuals spawning in the Gulf of Mexico, and smaller individuals spawning in the Slope Sea. The current life history model, which assumes only Gulf of Mexico spawning, overestimates age at maturity for the western stock. Furthermore, individual tuna occupy both the Slope Sea and Mediterranean Sea in separate years, contrary to the prevailing view that individuals exhibit complete spawning-site fidelity. Overall, this complexity of spawning migrations questions whether there is complete independence in the dynamics of eastern and western Atlantic bluefin tuna and leads to lower estimates of the vulnerability of this species to exploitation and other anthropogenic stressors.

Discovery of a spawning ground reveals diverse migration strategies in Atlantic bluefin tuna (Thunnus thynnus)

PubMed Central

Richardson, David E.; Marancik, Katrin E.; Guyon, Jeffrey R.; Lutcavage, Molly E.; Galuardi, Benjamin; Lam, Chi Hin; Walsh, Harvey J.; Wildes, Sharon; Yates, Douglas A.; Hare, Jonathan A.

2016-01-01

Atlantic bluefin tuna are a symbol of both the conflict between preservationist and utilitarian views of top ocean predators, and the struggle to reach international consensus on the management of migratory species. Currently, Atlantic bluefin tuna are managed as an early-maturing eastern stock, which spawns in the Mediterranean Sea, and a late-maturing western stock, which spawns in the Gulf of Mexico. However, electronic tagging studies show that many bluefin tuna, assumed to be of a mature size, do not visit either spawning ground during the spawning season. Whether these fish are spawning in an alternate location, skip-spawning, or not spawning until an older age affects how vulnerable this species is to anthropogenic stressors including exploitation. We use larval collections to demonstrate a bluefin tuna spawning ground in the Slope Sea, between the Gulf Stream and northeast United States continental shelf. We contend that western Atlantic bluefin tuna have a differential spawning migration, with larger individuals spawning in the Gulf of Mexico, and smaller individuals spawning in the Slope Sea. The current life history model, which assumes only Gulf of Mexico spawning, overestimates age at maturity for the western stock. Furthermore, individual tuna occupy both the Slope Sea and Mediterranean Sea in separate years, contrary to the prevailing view that individuals exhibit complete spawning-site fidelity. Overall, this complexity of spawning migrations questions whether there is complete independence in the dynamics of eastern and western Atlantic bluefin tuna and leads to lower estimates of the vulnerability of this species to exploitation and other anthropogenic stressors. PMID:26951668

Mechanistic insights into the effects of climate change on larval cod.

PubMed

Kristiansen, Trond; Stock, Charles; Drinkwater, Kenneth F; Curchitser, Enrique N

2014-05-01

Understanding the biophysical mechanisms that shape variability in fisheries recruitment is critical for estimating the effects of climate change on fisheries. In this study, we used an Earth System Model (ESM) and a mechanistic individual-based model (IBM) for larval fish to analyze how climate change may impact the growth and survival of larval cod in the North Atlantic. We focused our analysis on five regions that span the current geographical range of cod and are known to contain important spawning populations. Under the SRES A2 (high emissions) scenario, the ESM-projected surface ocean temperatures are expected to increase by >1 °C for 3 of the 5 regions, and stratification is expected to increase at all sites between 1950-1999 and 2050-2099. This enhanced stratification is projected to decrease large (>5 μm ESD) phytoplankton productivity and mesozooplankton biomass at all 5 sites. Higher temperatures are projected to increase larval metabolic costs, which combined with decreased food resources will reduce larval weight, increase the probability of larvae dying from starvation and increase larval exposure to visual and invertebrate predators at most sites. If current concentrations of piscivore and invertebrate predators are maintained, larval survival is projected to decrease at all five sites by 2050-2099. In contrast to past observed responses to climate variability in which warm anomalies led to better recruitment in cold-water stocks, our simulations indicated that reduced prey availability under climate change may cause a reduction in larval survival despite higher temperatures in these regions. In the lower prey environment projected under climate change, higher metabolic costs due to higher temperatures outweigh the advantages of higher growth potential, leading to negative effects on northern cod stocks. Our results provide an important first large-scale assessment of the impacts of climate change on larval cod in the North Atlantic. © 2013 John Wiley & Sons Ltd.

Severe tissue damage in Atlantic cod larvae under increasing ocean acidification

NASA Astrophysics Data System (ADS)

Frommel, Andrea Y.; Maneja, Rommel; Lowe, David; Malzahn, Arne M.; Geffen, Audrey J.; Folkvord, Arild; Piatkowski, Uwe; Reusch, Thorsten B. H.; Clemmesen, Catriona

2012-01-01

Ocean acidification, caused by increasing atmospheric concentrations of CO2 (refs , , ), is one of the most critical anthropogenicthreats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid-base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, leading to long-term effects such as reduced growth rates and reproduction. In teleost fishes, early life-history stages are particularly vulnerable as they lack specialized internal pH regulatory mechanisms. So far, impacts of relevant CO2 concentrations on larval fish have been found in behaviour and otolith size, mainly in tropical, non-commercial species. Here we show detrimental effects of ocean acidification on the development of a mass-spawning fish species of high commercial importance. We reared Atlantic cod larvae at three levels of CO2, (1) present day, (2) end of next century and (3) an extreme, coastal upwelling scenario, in a long-term ( months) mesocosm experiment. Exposure to CO2 resulted in severe to lethal tissue damage in many internal organs, with the degree of damage increasing with CO2 concentration. As larval survival is the bottleneck to recruitment, ocean acidification has the potential to act as an additional source of natural mortality, affecting populations of already exploited fish stocks.

Effects of alkylphenols on CYP1A and CYP3A expression in first spawning Atlantic cod (Gadus morhua).

PubMed

Hasselberg, Linda; Meier, Sonnich; Svardal, Asbjørn; Hegelund, Tove; Celander, Malin C

2004-05-12

Alkylphenols are continuously released into the ocean as a result of offshore oil production. Alkylphenols, including 4-tert-butylphenol (C4), 4n-pentylphenol (C5), 4n-hexylphenol (C6), and 4n-heptylphenol (C7), up to 237 ppb concentrations, have been detected in produced water from oil platforms. Previous studies have shown that alkylphenols induce vitellogenesis in fish. Atlantic cod (Gadus morhua) of both sexes were force-fed with various doses ranging between 0.02 and 80 ppm of a mixture of alkylphenols (C4:C5:C6:C7 ratio 1:1:1:1) or 5 ppm 17 beta-estradiol. We investigated effects on hepatic CYP1A and CYP3A protein expression in protein blots, using antibodies against scup (Stenotomus chrysops) CYP1A1 and rainbow trout (Oncorhynchus mykiss) CYP3A. There was a sexually dimorphic expression of CYP1A and CYP3A protein levels, with females expressing higher levels than males. Treatment of male Atlantic cod with 17 beta-estradiol resulted in increased CYP1A and CYP3A protein levels. Exposure to alkylphenols resulted in a dose-dependent increase of CYP1A and CYP3A protein expression in males, but not in females. However, this increase of CYP1A protein levels was not reflected on the CYP1A-mediated ethoxyresorufin-O-deethylase (EROD) activity, implying that alkylphenols inhibited the CYP1A enzyme activity in vivo. In vitro inhibition studies with pooled liver microsomes from Atlantic cod confirmed that the alkylphenols mixture efficiently inhibited the CYP1A activity (IC50=10 microM), although the inhibitory effect of each individual alkylphenol varied. The IC50 values for each individual alkylphenol on the CYP1A activity were, in a descending order of magnitude: [C7>C6>C5>C4], ranging from 12 to 300 microM with decreased length of the 4-alkyl chain. The effect of alkylphenols on the CYP3A activity in vitro in liver microsomes also was investigated, using the fluorescent 7-benzyloxy-4-[trifluoromethyl]-coumarin (BFC) as a diagnostic CYP3A substrate. The alkylphenol mixture inhibited CYP3A activity with IC50 value at 100 microM. The IC50 values for each individual alkylphenol on CYP3A activity were, in a descending order of magnitude: [C5>C6>C7>C4], ranging between 60 and 250 microM. Taken together, our results show that the alkylphenol mixture and 17 beta-estradiol resulted in elevated hepatic CYP1A and CYP3A expression in male Atlantic cod. The alkylphenol mixture strongly inhibited CYP1A activities, whereas it weakly inhibited CYP3A activity in Atlantic cod liver microsomes in vitro. In addition, 17 beta-estradiol was a weak inhibitor of CYP3A activity (IC50=75 microM) and did not notably inhibit the CYP1A activity in vitro.

Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil.

PubMed

Stige, Leif Chr; Ottersen, Geir; Yaragina, Natalia A; Vikebø, Frode B; Stenseth, Nils Chr; Langangen, Øystein

2018-04-01

It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959-1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fall spawning of Atlantic sturgeon in the Roanoke River, North Carolina

USGS Publications Warehouse

Smith, Joseph A.; Hightower, Joseph E.; Flowers, H. Jared

2015-01-01

In 2012, the National Oceanic and Atmospheric Administration (NOAA) declared Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus to be threatened or endangered throughout its range in U.S. waters. Restoration of the subspecies will require much new information, particularly on the location and timing of spawning. We used a combination of acoustic telemetry and sampling with anchored artificial substrates (spawning pads) to detect fall (September–November) spawning in the Roanoke River in North Carolina. This population is included in the Carolina Distinct Population Segment, which was classified by NOAA as endangered. Sampling was done immediately below the first shoals encountered by anadromous fishes, near Weldon. Our collection of 38 eggs during the 21 d that spawning pads were deployed appears to be the first such collection (spring or fall) for wild-spawned Atlantic Sturgeon eggs. Based on egg development stages, estimated spawning dates were September 17–18 and 18–19 at water temperatures from 25.3°C to 24.3°C and river discharge from 55 to 297 m3/s. These observations about fall spawning and habitat use should aid in protecting critical habitats and planning research on Atlantic Sturgeon spawning in other rivers.

Climate variability and the Icelandic marine ecosystem

NASA Astrophysics Data System (ADS)

Astthorsson, Olafur S.; Gislason, Astthor; Jonsson, Steingrimur

2007-11-01

This paper describes the main features of the Icelandic marine ecosystem and its response to climate variations during the 20th century. The physical oceanographic character and faunal composition in the southern and western parts of the Icelandic marine ecosystem are different from those in the northern and the eastern areas. The former areas are more or less continuously bathed by warm and saline Atlantic water while the latter are more variable and influenced by Atlantic, Arctic and even Polar water masses to different degrees. Mean annual primary production is higher in the Atlantic water than in the more variable waters north and east of Iceland, and higher closer to land than farther offshore. Similarly, zooplankton production is generally higher in the Atlantic water than in the waters north and east of Iceland. The main spawning grounds of most of the exploited fish stocks are in the Atlantic water south of the country while nursery grounds are off the north coast. In the recent years the total catch of fish and invertebrates has been in the range of 1.6-2.4 million ton. Capelin ( Mallotus villosus) is the most important pelagic stock and cod ( Gadus morhua) is by far the most important demersal fish stock. Whales are an important component of the Icelandic marine ecosystem, and Icelandic waters are an important habitat for some of the largest seabird populations in the Northeast Atlantic. In the waters to the north and east of Iceland, available information suggests the existence of a simple bottom-up controlled food chain from phytoplankton through Calanus, capelin and to cod. Less is known about the structure of the more complex southern part of the ecosystem. The Icelandic marine ecosystem is highly sensitive to climate variations as demonstrated by abundance and distribution changes of many species during the warm period in the 1930s, the cold period in the late 1960s and warming observed during the recent years. Some of these are highlighted in the paper.

Shifting distributions of adult Atlantic sturgeon amidst post-industrialization and future impacts in the Delaware River: a maximum entropy approach.

PubMed

Breece, Matthew W; Oliver, Matthew J; Cimino, Megan A; Fox, Dewayne A

2013-01-01

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) experienced severe declines due to habitat destruction and overfishing beginning in the late 19(th) century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeon under the Endangered Species Act. Although habitats may be improving, the availability of high quality spawning habitat, essential for the survival and development of eggs and larvae may still be a limiting factor in the recovery of Atlantic sturgeon. To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, we utilized a maximum entropy (MaxEnt) approach along with passive biotelemetry during the likely spawning season. We found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic sturgeon in the Delaware River. To broaden the scope of this study we projected our model onto four scenarios depicting varying locations of the salt front in the Delaware River: the contemporary location of the salt front during the likely spawning season, the location of the salt front during the historic fishery in the late 19(th) century, an estimated shift in the salt front by the year 2100 due to climate change, and an extreme drought scenario, similar to that which occurred in the 1960's. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic sturgeon spawning may be taking place. Identifying where suitable spawning substrate and water chemistry intersect with the likely occurrence of adult Atlantic sturgeon in the Delaware River highlights essential spawning habitats, enhancing recovery prospects for this imperiled species.

Comparative Assessment of the Reproductive Status of Female Atlantic Bluefin Tuna from the Gulf of Mexico and the Mediterranean Sea

PubMed Central

Knapp, Jessica M.; Aranda, Guillermo; Medina, Antonio; Lutcavage, Molly

2014-01-01

Despite attention focused on the population status and rebuilding trajectory of Atlantic bluefin tuna (Thunnus thynnus), the reproduction and spawning biology remains poorly understood, especially in the NW Atlantic. At present, the eastern and western spawning populations are believed to exhibit different reproductive characteristics and, consequently, stock productivity. However, our study suggests that the two spawning populations, the Gulf of Mexico and the Mediterranean Sea, could show similar reproductive features and spawning strategies. Between 2007 and 2009, gonad samples from female Atlantic bluefin tuna were collected in the northern Gulf of Mexico (n = 147) and in the western Mediterranean Sea (n = 40). The histological and stereological analysis confirmed that sampled eastern and western bluefin tuna exhibit the same spawning duration (three months) but the spawning in the Gulf of Mexico begins one month earlier than in the Mediterranean Sea. Western bluefin tuna caught in the peak of the spawning season (May) showed a similar spawning frequency (60%) to the spawning peak observed in the Mediterranean Sea (June). Fecundity for the Gulf of Mexico fish () was lower but not significantly different than for fish sampled in the Mediterranean Sea (). Our study represents the first comparative histological analysis of the eastern and western spawning stocks whose findings, combined with new determinations of size/age at maturity and possible alternative spawning areas, might suggest basic life history attributes warrant further scientific and management attention. PMID:24911973

Comparative assessment of the reproductive status of female Atlantic bluefin tuna from the Gulf of Mexico and the Mediterranean Sea.

PubMed

Knapp, Jessica M; Aranda, Guillermo; Medina, Antonio; Lutcavage, Molly

2014-01-01

Despite attention focused on the population status and rebuilding trajectory of Atlantic bluefin tuna (Thunnus thynnus), the reproduction and spawning biology remains poorly understood, especially in the NW Atlantic. At present, the eastern and western spawning populations are believed to exhibit different reproductive characteristics and, consequently, stock productivity. However, our study suggests that the two spawning populations, the Gulf of Mexico and the Mediterranean Sea, could show similar reproductive features and spawning strategies. Between 2007 and 2009, gonad samples from female Atlantic bluefin tuna were collected in the northern Gulf of Mexico (n = 147) and in the western Mediterranean Sea (n = 40). The histological and stereological analysis confirmed that sampled eastern and western bluefin tuna exhibit the same spawning duration (three months) but the spawning in the Gulf of Mexico begins one month earlier than in the Mediterranean Sea. Western bluefin tuna caught in the peak of the spawning season (May) showed a similar spawning frequency (60%) to the spawning peak observed in the Mediterranean Sea (June). Fecundity for the Gulf of Mexico fish (28.14 eggs · g(-1)) was lower but not significantly different than for fish sampled in the Mediterranean Sea (45.56 eggs · g(-1)). Our study represents the first comparative histological analysis of the eastern and western spawning stocks whose findings, combined with new determinations of size/age at maturity and possible alternative spawning areas, might suggest basic life history attributes warrant further scientific and management attention.

Net-mortality of Common Murres and Atlantic Puffins in Newfoundland, 1951-81

USGS Publications Warehouse

Piatt, John F.; Nettleship, David N.; Threlfall, William; Nettleship, David N.; Sanger, Gerald A.; Springer, Paul F.

1982-01-01

Band recoveries (N = 315) over 26 years (1951-77) and three surveys of seabird bycatch in inshore fishing nets (1972, 1980-81) indicate that there has been a substantial net-mortality of Atlantic Puffins (Fratercula arctica) and Common Murres (Uria aalge) in Newfoundland coastal waters for the past 2 decades. Offshore (e.g. Grand Banks) gill-netting is limited, but some data suggest that murre net-mortality also occurs offshore at murre wintering areas. The vast majority of inshore net-mortality incidents occur over a 2-week period during the annual inshore spawning migration of capelin (Mallotus villosus), the major prey item for alcids in eastern Canada. Most murres (83%) were drowned in bottom-set (30-185 m) cod (Gadus morhua) gill nets, whereas more puffins were drowned in surface-set salmon (Salmo salar) gill nets or cod traps (55%) than in cod gillnets (45%). Murre band recoveries, colony censuses, and fishing-effort data suggest that at the second largest Common Murre colony in Newfoundland (Witless Bay Seabird Sanctuary, 77,000 breeding pairs) net-mortality was relatively low in the 1950s and early 1960s, but increased during the 1960s as the murre population grew in size and gill-net fishing effort increased in the colony area. By 1971, net-mortality accounted for 70% of murre band recoveries and calculations show that almost 30,000 breeding adults, or about 20% of the local breeding population, were drowned in that year. More reliable estimates of alcid bycatch in the Witless Bay area have been made on the basis of actual bycatch surveys. In 1972 about 20,000 adult murres, or 13% of the breeding stock, were killed in gill-nets. Net-mortality of murres apparently diminished through the 1970s as capelin stocks declined and fewer birds foraged in heavily netted inshore areas. Bycatch surveys in the Witless Bay area in 1980-81 revealed that, relative to previous years, murre net-mortality was greatly reduced and resulted in the loss of only 3-4% of the breeding stock. Even these low mortality rates, however, are cause for concern as adult murre mortality from all sources (including hunting, oil, and natural mortality) should not exceed 6-12% per annum to maintain a stable breeding population. Little is known about the magnitude of net-mortality at other major Newfoundland murre colonies though it is known to be a problem in all colony areas. The bycatch of adult Atlantic Puffins in the Witless Bay area was low compared to murre bycatch and in 3 years of study never exceeded 1.6% of the breeding population. During the 1970s, fishing effort increased five-fold in colony areas and we predict that if capelin spawning stocks return to early 1970s size, then net-mortality of puffins and murres in Newfoundland coastal regions will increase dramatically. Indeed, preliminary examination of 1982 capelin spawning and seabird bycatch data suggests that capelin were much more abundant inshore and murre bycatch increased two- to three-fold over 1981.

Preferred temperature of juvenile Atlantic cod Gadus morhua with different haemoglobin genotypes at normoxia and moderate hypoxia.

PubMed

Petersen, Maria Faldborg; Steffensen, John Fleng

2003-01-01

Atlantic cod Gadus morhua has polymorphic haemoglobin, which can be separated into two homozygous types, HbI-1 and HbI-2, and one heterozygous type HbI-1/2. The geographical distribution of Atlantic cod with the different haemoglobin types varies, with the HbI(2) allele occurring at high frequency in northern regions, and the HbI(1) allele dominant in warmer areas. To determine if temperature is a selective parameter in the distribution of the haemoglobin types, the preferred temperature of the homozygous genotypes HbI-1 and HbI-2 was measured. We found that HbI-2 cod preferred a temperature of 8.2+/-1.5 degrees C while HbI-1 cod preferred 15.4+/-1.1 degrees C, and this preference was significant. The effect of hypoxia (35% oxygen saturation) on the preferred temperature was also measured. Previous studies showed that the preferred temperature of fish decreases during hypoxia, and this was the case for HbI-1 cod, which preferred 9.8+/-1.8 degrees C during hypoxia, whereas HbI-2 cod did not show this effect. The results indicate that environmental temperature changes will lead to a distributional change in the different haemoglobin types of Atlantic cod, global warming providing an advantage for HbI-1 cod. However, since HbI-1 cod prefer a low temperature under hypoxic conditions, a combination of increased water temperature and hypoxia could be unfavourable for Atlantic cod stocks.

Mitochondrial acclimation potential to ocean acidification and warming of Polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua).

PubMed

Leo, Elettra; Kunz, Kristina L; Schmidt, Matthias; Storch, Daniela; Pörtner, Hans-O; Mark, Felix C

2017-01-01

Ocean acidification and warming are happening fast in the Arctic but little is known about the effects of ocean acidification and warming on the physiological performance and survival of Arctic fish. In this study we investigated the metabolic background of performance through analyses of cardiac mitochondrial function in response to control and elevated water temperatures and P CO 2 of two gadoid fish species, Polar cod ( Boreogadus saida ), an endemic Arctic species, and Atlantic cod ( Gadus morhua ), which is a temperate to cold eurytherm and currently expanding into Arctic waters in the wake of ocean warming. We studied their responses to the above-mentioned drivers and their acclimation potential through analysing the cardiac mitochondrial function in permeabilised cardiac muscle fibres after 4 months of incubation at different temperatures (Polar cod: 0, 3, 6, 8 °C and Atlantic cod: 3, 8, 12, 16 °C), combined with exposure to present (400μatm) and year 2100 (1170μatm) levels of CO 2 . OXPHOS, proton leak and ATP production efficiency in Polar cod were similar in the groups acclimated at 400μatm and 1170μatm of CO 2 , while incubation at 8 °C evoked increased proton leak resulting in decreased ATP production efficiency and decreased Complex IV capacity. In contrast, OXPHOS of Atlantic cod increased with temperature without compromising the ATP production efficiency, whereas the combination of high temperature and high P CO 2 depressed OXPHOS and ATP production efficiency. Polar cod mitochondrial efficiency decreased at 8 °C while Atlantic cod mitochondria were more resilient to elevated temperature; however, this resilience was constrained by high P CO 2 . In line with its lower habitat temperature and higher degree of stenothermy, Polar cod has a lower acclimation potential to warming than Atlantic cod.

Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). Atlantic and Shortnosed Sturgeons

DTIC Science & Technology

1989-12-01

for the Atlantic sturgeon were the St. Johns River, Florida, suggests that lack characterized by relatively slow current, turbid of documented spawning...apparently fccd mostly at spcees that might also spawn over sturgeon night or on windy d,.vs when turbidity is high spawning grounds include walleye...Beginning Feeding apparently occurs mostly at night or on in the early 1870’s, the taste of sturgeon flesh windy days when turbidity is high and

Shifting Distributions of Adult Atlantic Sturgeon Amidst Post-Industrialization and Future Impacts in the Delaware River: a Maximum Entropy Approach

PubMed Central

Breece, Matthew W.; Oliver, Matthew J.; Cimino, Megan A.; Fox, Dewayne A.

2013-01-01

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) experienced severe declines due to habitat destruction and overfishing beginning in the late 19th century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeon under the Endangered Species Act. Although habitats may be improving, the availability of high quality spawning habitat, essential for the survival and development of eggs and larvae may still be a limiting factor in the recovery of Atlantic sturgeon. To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, we utilized a maximum entropy (MaxEnt) approach along with passive biotelemetry during the likely spawning season. We found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic sturgeon in the Delaware River. To broaden the scope of this study we projected our model onto four scenarios depicting varying locations of the salt front in the Delaware River: the contemporary location of the salt front during the likely spawning season, the location of the salt front during the historic fishery in the late 19th century, an estimated shift in the salt front by the year 2100 due to climate change, and an extreme drought scenario, similar to that which occurred in the 1960’s. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic sturgeon spawning may be taking place. Identifying where suitable spawning substrate and water chemistry intersect with the likely occurrence of adult Atlantic sturgeon in the Delaware River highlights essential spawning habitats, enhancing recovery prospects for this imperiled species. PMID:24260570

Effect of a fish stock's demographic structure on offspring survival and sensitivity to climate.

PubMed

Stige, Leif Christian; Yaragina, Natalia A; Langangen, Øystein; Bogstad, Bjarte; Stenseth, Nils Chr; Ottersen, Geir

2017-02-07

Commercial fishing generally removes large and old individuals from fish stocks, reducing mean age and age diversity among spawners. It is feared that these demographic changes lead to lower and more variable recruitment to the stocks. A key proposed pathway is that juvenation and reduced size distribution causes reduced ranges in spawning period, spawning location, and egg buoyancy; this is proposed to lead to reduced spatial distribution of fish eggs and larvae, more homogeneous ambient environmental conditions within each year-class, and reduced buffering against negative environmental influences. However, few, if any, studies have confirmed a causal link from spawning stock demographic structure through egg and larval distribution to year class strength at recruitment. We here show that high mean age and size in the spawning stock of Barents Sea cod (Gadus morhua) is positively associated with high abundance and wide spatiotemporal distribution of cod eggs. We find, however, no support for the hypothesis that a wide egg distribution leads to higher recruitment or a weaker recruitment-temperature correlation. These results are based on statistical analyses of a spatially resolved data set on cod eggs covering a period (1959-1993) with large changes in biomass and demographic structure of spawners. The analyses also account for significant effects of spawning stock biomass and a liver condition index on egg abundance and distribution. Our results suggest that the buffering effect of a geographically wide distribution of eggs and larvae on fish recruitment may be insignificant compared with other impacts.

Composition and structure of the parasite faunas of cod, Gadus morhua L. (Teleostei: Gadidae), in the North East Atlantic.

PubMed

Perdiguero-Alonso, Diana; Montero, Francisco E; Raga, Juan Antonio; Kostadinova, Aneta

2008-07-18

Although numerous studies on parasites of the Atlantic cod, Gadus morhua L. have been conducted in the North Atlantic, comparative analyses on local cod parasite faunas are virtually lacking. The present study is based on examination of large samples of cod from six geographical areas of the North East Atlantic which yielded abundant baseline data on parasite distribution and abundance. A total of 826 fish was sampled in the Baltic, Celtic, Irish and North seas, Icelandic waters and Trondheimsfjord (Norway) in 2002 (spring and autumn) and 2003 (spring). The gills and internal organs (oesophagus, stomach, intestine, pyloric caeca, liver, heart, spleen, gall bladder and gonads) were examined for macroparasites following a standardised protocol. The taxonomic consistency of the identification was ensured thorough the entire study. We discuss some problems in parasite identification, outline the composition of the parasite faunas in cod in the six North East Atlantic regions, provide novel data on parasite prevalence and abundance and a comparative assessment of the structure of the regional parasite faunas with respect to the higher-level taxonomic groupings, host specificity and zoogeographical distribution of the parasites. Altogether 57 different parasite forms were found including seven new host records (Diclidophora merlangi, Rhipidocotyle sp., Fellodistomum sp., Steringotrema sp., Cucullanus sp., Spinitectus sp., and Chondracanthus ornatus). The predominant groups of cod parasites were trematodes (19 species) and nematodes (13 species) including larval anisakids which comprised 58.2% of the total number of individuals. Our study reveals relatively rich regional parasite faunas in cod from the North East Atlantic which are dominated by generalist parasites with Arcto-Boreal distribution. Further, it provides more detailed data on the distribution in the North East Atlantic of the majority of cod parasites which may serve as baselines for future studies on the effect of climate change. Based on the faunal comparisons, predictions can be made in relation to the structure and diversity of the parasite communities in the North East Atlantic regions studied.

Spatio-temporal dynamics of cod nursery areas in the Baltic Sea

NASA Astrophysics Data System (ADS)

Hinrichsen, H.-H.; von Dewitz, B.; Lehmann, A.; Bergström, U.; Hüssy, K.

2017-06-01

In this study the drift of eastern Baltic cod larvae and juveniles spawned within the historical eastern Baltic cod spawning grounds was investigated by detailed drift model simulations for the years 1971-2010, to examine the spatio-temporal dynamics of environmental suitability in the nursery areas of juvenile cod settlement. The results of the long-term model scenario runs, where juvenile cod were treated as simulated passively drifting particles, enabled us to find strong indications for long-term variations of settlement and potentially the reproduction success of the historically important eastern Baltic cod nursery grounds. Only low proportions of juveniles hatched in the Arkona Basin and in the Gotland Basin were able to settle in their respective spawning ground. Ocean currents were either unfavorable for the juveniles to reach suitable habitats or transported the juveniles to nursery grounds of neighboring subdivisions. Juveniles which hatched in the Bornholm Basin were most widely dispersed and showed the highest settlement probability, while the second highest settlement probability and horizontal dispersal was observed for juveniles originating from the Gdansk Deep. In a long-term perspective, wind-driven transport of larvae/juveniles positively affected the settlement success predominately in the Bornholm Basin and in the Bay of Gdansk. The Bornholm Basin has the potential to contribute on average 54% and the Bay of Gdansk 11% to the production of juveniles in the Baltic Sea. Furthermore, transport of juveniles surviving to the age of settlement with origin in the Bornholm Basin contributed on average 13 and 11% to the total settlement in the Arkona Basin and in the Gdansk Deep, respectively. The time-series of the simulated occupied juvenile cod habitat in the Bornholm Basin and in the Gdansk Deep showed a similar declining trend as the Fulton's K condition factor of demersal 1-group cod, which may confirm the importance of oxygen-dependent habitat availability and its effect on density dependence as a process relevant for recruitment success.

Coronary arteriosclerosis in Atlantic salmon. No regression of lesions after spawning.

PubMed

Saunders, R L; Farrell, A P

1988-01-01

The incidence and severity of coronary arteriosclerosis were studied in 209 wild and cultured Atlantic salmon (Salmo salar L.) during various stages of recovery of bodily condition after spawning. All recently spawned fish had lesions of moderate to extreme severity. The incidence of lesions for each fish was high (73% to 94% of all arterial cross-sections examined). The incidence and severity of lesions did not decrease during 5 months in a group of wild salmon reconditioned in the laboratory. Wild salmon that were examined in the spring angling fishery in the Miramichi River, New Brunswick, about 5 months after spawning had a high incidence (89%) of severe lesions, not significantly different from recently spawned salmon from the same and another river. A population of cultured salmon sampled at intervals from a sea cage during 9 months after spawning showed no evidence of lesion regression, but rather a continued increase in both incidence and severity during recovery of bodily condition and growth. Thus, in contrast with previous studies with steelhead trout and Atlantic salmon where the possibility of lesion regression has been suggested, our observations on a large number of Atlantic salmon from various sources gave no evidence of lesion regression. Coronary arteriosclerosis in Salmo salar appears to be a progressive condition, which continues during recovery of bodily condition and growth after spawning.

Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (South Atlantic) - Atlantic sturgeon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Den Avyle, M.J.

1984-07-01

The Atlantic sturgeon, Acipenser oxyrhynchus oxyrhynchus, is an anadromous species that occupies rivers, estuaries, and nearshore waters along the entire Atlantic coast of the United States. The species once supported significant commercial fisheries throughout its range, but stocks have declined because of overfishing, deterioration of water quality, and damming of rivers. Atlantic sturgeon spawn in rivers and the young remain in freshwater for several years prior to emigration to the ocean. Little is known about spawning areas and associated environmental factors. Females typically do not mature until age X and the age at first spawning ranges from 5 to 13more » years for males and 7 to 19 years for females. Longevity may frequently exceed 25 years. Immature and adult sturgeons are bottom feeders and consume a variety of mollusks, crustaceans, worms, and other small bottom-dwelling invertebrates and fishes. Little is know about competitors, predators, or effects of environmental factors on recruitment. The long period required to reach maturity, possibly irregular spawning thereafter, and prolonged reliance on river systems make juvenile and adult Atlantic sturgeon highly susceptible to habitat alterations, pollution, and over exploitation. 49 references, 2 figures, 4 tables.« less

Low plastic ingestion rate in Atlantic cod (Gadus morhua) from Newfoundland destined for human consumption collected through citizen science methods.

PubMed

Liboiron, Max; Liboiron, France; Wells, Emily; Richárd, Natalie; Zahara, Alexander; Mather, Charles; Bradshaw, Hillary; Murichi, Judyannet

2016-12-15

Marine microplastics are a contaminant of concern because their small size allows ingestion by a wide range of marine life. Using citizen science during the Newfoundland recreational cod fishery, we sampled 205 Atlantic cod (Gadus morhua) destined for human consumption and found that 5 had eaten plastic, an ingestion prevalence rate of 2.4%. This ingestion rate for Atlantic cod is the second lowest recorded rate in the reviewed published literature (the lowest is 1.4%), and the lowest for any fish in the North Atlantic. This is the first report for plastic ingestion in fish in Newfoundland, Canada, a province dependent on fish for sustenance and livelihoods. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oxygen depletion in coastal seas and the effective spawning stock biomass of an exploited fish species

PubMed Central

Hinrichsen, H.-H.; von Dewitz, B.; Dierking, J.; Haslob, H.; Makarchouk, A.; Petereit, C.; Voss, R.

2016-01-01

Environmental conditions may have previously underappreciated effects on the reproductive processes of commercially exploited fish populations, for example eastern Baltic cod, that are living at the physiological limits of their distribution. In the Baltic Sea, salinity affects neutral egg buoyancy, which is positively correlated with egg survival, as only water layers away from the oxygen consumption-dominated sea bottom contain sufficient oxygen. Egg buoyancy is positively correlated to female spawner age/size. From observations in the Baltic Sea, a field-based relationship between egg diameter and buoyancy (floating depth) could be established. Hence, based on the age structure of the spawning stock, we quantify the number of effective spawners, which are able to reproduce under ambient hydrographic conditions. For the time period 1993–2010, our results revealed large variations in the horizontal extent of spawning habitat (1000–20 000 km2) and oxygen-dependent egg survival (10–80%). The novel concept of an effective spawning stock biomass takes into account offspring that survive depending on the spawning stock age/size structure, if reproductive success is related to egg buoyancy and the extent of hypoxic areas. Effective spawning stock biomass reflected the role of environmental conditions for Baltic cod recruitment better than the spawning stock biomass alone, highlighting the importance of including environmental information in ecosystem-based management approaches. PMID:26909164

Effect of a fish stock's demographic structure on offspring survival and sensitivity to climate

PubMed Central

Stige, Leif Christian; Yaragina, Natalia A.; Langangen, Øystein; Bogstad, Bjarte; Stenseth, Nils Chr.; Ottersen, Geir

2017-01-01

Commercial fishing generally removes large and old individuals from fish stocks, reducing mean age and age diversity among spawners. It is feared that these demographic changes lead to lower and more variable recruitment to the stocks. A key proposed pathway is that juvenation and reduced size distribution causes reduced ranges in spawning period, spawning location, and egg buoyancy; this is proposed to lead to reduced spatial distribution of fish eggs and larvae, more homogeneous ambient environmental conditions within each year-class, and reduced buffering against negative environmental influences. However, few, if any, studies have confirmed a causal link from spawning stock demographic structure through egg and larval distribution to year class strength at recruitment. We here show that high mean age and size in the spawning stock of Barents Sea cod (Gadus morhua) is positively associated with high abundance and wide spatiotemporal distribution of cod eggs. We find, however, no support for the hypothesis that a wide egg distribution leads to higher recruitment or a weaker recruitment–temperature correlation. These results are based on statistical analyses of a spatially resolved data set on cod eggs covering a period (1959−1993) with large changes in biomass and demographic structure of spawners. The analyses also account for significant effects of spawning stock biomass and a liver condition index on egg abundance and distribution. Our results suggest that the buffering effect of a geographically wide distribution of eggs and larvae on fish recruitment may be insignificant compared with other impacts. PMID:28115694

Characterization of the spawning habitat of Atlantic bluefin tuna and related species in the Balearic Sea (western Mediterranean)

NASA Astrophysics Data System (ADS)

Alemany, F.; Quintanilla, L.; Velez-Belchí, P.; García, A.; Cortés, D.; Rodríguez, J. M.; Fernández de Puelles, M. L.; González-Pola, C.; López-Jurado, J. L.

2010-07-01

Within the framework of the TUNIBAL project that focused on Atlantic bluefin tuna ( Thunnus thynnus) larval ecology, ichthyoplankton surveys were conducted from 2001 to 2005 off the Balearic archipelago, which is recognized as one of the main spawning areas of the eastern Atlantic stock of this species. In each survey, a regular sampling grid of about 200 stations, 10 nautical miles apart were sampled. CTD casts and oblique Bongo 60 and surface Bongo 90 plankton tows were carried out. The occurrence frequencies of Atlantic bluefin tuna, albacore tuna ( Thunnus alalunga) and bullet tuna ( Auxis rochei) larvae in quantitative Bongo 60 samples were 0.14, 0.29 and 0.49 respectively. Mean larval abundances in these positive samples were relatively high: 31 larvae 10 m -2 for Atlantic bluefin tuna, 17 for albacore tuna and 31 for bullet tuna. All species had patchy distributions since more than 90% of the stations showed larval densities under 10 larvae 100 m -3 (70% showed even less than 2 larvae 100 m -3), whereas in some isolated spots, we recorded abundances as high as 867 (Atlantic bluefin) or 872 (bullet tuna) larvae 10 m -2. These results allowed us to relate larval distribution to mesoscale hydrographic features and to characterize the spawning habitat of these species. Single Quotient Parameter analyses were applied to spatial (depth), physical (temperature, salinity, dissolved oxygen and geostrophic current velocities) and biological (mesozooplankton biomass) variables to determine the environmental preferences of each species for spawning. Results showed that the complex hydrodynamic scenarios around the Balearic Islands, due to the interaction between the inflowing surface Atlantic water masses (AW) and Mediterranean surface waters (MW), play a key role in determining the abundance and distribution of tuna larvae in this area, especially in the case of Atlantic bluefin tuna. Spawning of this species seems to take place mainly in offshore mixed waters, as suggested by their preferences for waters with salinities between 36.9 and 37.7, located near frontal areas in the confluence of AW and MW. Atlantic bluefin tuna start to spawn once sea surface temperatures (SST) are over 20.5 °C, and preferentially in the range of 21.5-26.5 °C. Its larval distribution suggests that spawners reach the Balearic Sea in association with the inflowing AW. However, bullet tuna and albacore tuna larvae, species whose Mediterranean stocks stay in this sea year round, had a more widespread distribution and were found both in MW and AW. Bullet tuna starts to spawn in shallower waters near the shelf break once the SST reaches 19 °C, and shows significant preferences for waters over 23.5 °C. Similar to Atlantic bluefin tuna, albacore tuna spawn in offshore waters, but its spawning peak is later than its congeneric species, since it has a significant preference for even warmer waters, over 27 °C.

Synergies between climate and management for Atlantic cod fisheries at high latitudes

PubMed Central

Kjesbu, Olav Sigurd; Bogstad, Bjarte; Devine, Jennifer A.; Gjøsæter, Harald; Howell, Daniel; Ingvaldsen, Randi B.; Nash, Richard D. M.; Skjæraasen, Jon Egil

2014-01-01

The widespread depletion of commercially exploited marine living resources is often seen as a general failure of management and results in criticism of contemporary management procedures. When populations show dramatic and positive changes in population size, this invariably leads to questions about whether favorable climatic conditions or good management (or both) were responsible. The Barents Sea cod (Gadus morhua) stock has recently increased markedly and the spawning stock biomass is now at an unprecedented high. We identify the crucial social and environmental factors that made this unique growth possible. The relationship between vital rates of Barents Sea cod stock productivity (recruitment, growth, and mortality) and environment is investigated, followed by simulations of population size under different management scenarios. We show that the recent sustained reduction in fishing mortality, facilitated by the implementation of a “harvest control rule,” was essential to the increase in population size. Simulations show that a drastic reduction in fishing mortality has resulted in a doubling of the total population biomass compared with that expected under the former management regime. However, management alone was not solely responsible. We document that prevailing climate, operating through several mechanistic links, positively reinforced management actions. Heightened temperature resulted in an increase in the extent of the suitable feeding area for Barents Sea cod, likely offering a release from density-dependent effects (for example, food competition and cannibalism) through prolonged overlap with prey and improved adult stock productivity. Management and climate may thus interact to give a positive outlook for exploited high-latitude marine resources. PMID:24550465

Synergies between climate and management for Atlantic cod fisheries at high latitudes.

PubMed

Kjesbu, Olav Sigurd; Bogstad, Bjarte; Devine, Jennifer A; Gjøsæter, Harald; Howell, Daniel; Ingvaldsen, Randi B; Nash, Richard D M; Skjæraasen, Jon Egil

2014-03-04

The widespread depletion of commercially exploited marine living resources is often seen as a general failure of management and results in criticism of contemporary management procedures. When populations show dramatic and positive changes in population size, this invariably leads to questions about whether favorable climatic conditions or good management (or both) were responsible. The Barents Sea cod (Gadus morhua) stock has recently increased markedly and the spawning stock biomass is now at an unprecedented high. We identify the crucial social and environmental factors that made this unique growth possible. The relationship between vital rates of Barents Sea cod stock productivity (recruitment, growth, and mortality) and environment is investigated, followed by simulations of population size under different management scenarios. We show that the recent sustained reduction in fishing mortality, facilitated by the implementation of a "harvest control rule," was essential to the increase in population size. Simulations show that a drastic reduction in fishing mortality has resulted in a doubling of the total population biomass compared with that expected under the former management regime. However, management alone was not solely responsible. We document that prevailing climate, operating through several mechanistic links, positively reinforced management actions. Heightened temperature resulted in an increase in the extent of the suitable feeding area for Barents Sea cod, likely offering a release from density-dependent effects (for example, food competition and cannibalism) through prolonged overlap with prey and improved adult stock productivity. Management and climate may thus interact to give a positive outlook for exploited high-latitude marine resources.

Effects of ocean acidification increase embryonic sensitivity to thermal extremes in Atlantic cod, Gadus morhua.

PubMed

Dahlke, Flemming T; Leo, Elettra; Mark, Felix C; Pörtner, Hans-Otto; Bickmeyer, Ulf; Frickenhaus, Stephan; Storch, Daniela

2017-04-01

Thermal tolerance windows serve as a powerful tool for estimating the vulnerability of marine species and their life stages to increasing temperature means and extremes. However, it remains uncertain to which extent additional drivers, such as ocean acidification, modify organismal responses to temperature. This study investigated the effects of CO 2 -driven ocean acidification on embryonic thermal sensitivity and performance in Atlantic cod, Gadus morhua, from the Kattegat. Fertilized eggs were exposed to factorial combinations of two PCO 2 conditions (400 μatm vs. 1100 μatm) and five temperature treatments (0, 3, 6, 9 and 12 °C), which allow identifying both lower and upper thermal tolerance thresholds. We quantified hatching success, oxygen consumption (MO 2 ) and mitochondrial functioning of embryos as well as larval morphometrics at hatch and the abundance of acid-base-relevant ionocytes on the yolk sac epithelium of newly hatched larvae. Hatching success was high under ambient spawning conditions (3-6 °C), but decreased towards both cold and warm temperature extremes. Elevated PCO 2 caused a significant decrease in hatching success, particularly at cold (3 and 0 °C) and warm (12 °C) temperatures. Warming imposed limitations to MO 2 and mitochondrial capacities. Elevated PCO 2 stimulated MO 2 at cold and intermediate temperatures, but exacerbated warming-induced constraints on MO 2 , indicating a synergistic interaction with temperature. Mitochondrial functioning was not affected by PCO 2 . Increased MO 2 in response to elevated PCO 2 was paralleled by reduced larval size at hatch. Finally, ionocyte abundance decreased with increasing temperature, but did not differ between PCO 2 treatments. Our results demonstrate increased thermal sensitivity of cod embryos under future PCO 2 conditions and suggest that acclimation to elevated PCO 2 requires reallocation of limited resources at the expense of embryonic growth. We conclude that ocean acidification constrains the thermal performance window of embryos, which has important implication for the susceptibility of cod to projected climate change. © 2016 John Wiley & Sons Ltd.

Cod Collapse and the Climate in the North Atlantic

NASA Astrophysics Data System (ADS)

Meng, K. C.; Oremus, K. L.; Gaines, S.

2014-12-01

Effective fisheries management requires forecasting population changes. We find a negative relationship between the North Atlantic Oscillation (NAO) index and subsequently surveyed biomass and catch of Atlantic cod, Gadus morhua, off the New England coast. A 1-unit NAO increase is associated with a 17% decrease in surveyed biomass of age-1 cod the following year. This relationship persists as the cod mature, such that observed NAO can be used to forecast future adult biomass. We also document that an NAO event lowers catch for up to 15 years afterward. In contrast to forecasts by existing stock assessment models, our NAO-driven statistical model successfully hindcasts the recent collapse of New England cod fisheries following strong NAO events in 2007 and 2008 (see figure). This finding can serve as a template for forecasting other fisheries affected by climatic conditions.

50 CFR 648.81 - NE multispecies closed areas and measures to protect EFH.

Code of Federal Regulations, 2012 CFR

2012-10-01

... designed and used to take surfclams or ocean quahogs, provided that there is no retention of regulated...′ 70°00′ 1 Cape Cod shoreline on the Atlantic Ocean. (ii) Rolling Closure Area II. From April 1 through... Cape Cod Bay. 3 Cape Cod shoreline on the Atlantic Ocean. 4 New Hampshire shoreline. (iii) Rolling...

50 CFR 648.81 - NE multispecies closed areas and measures to protect EFH.

Code of Federal Regulations, 2014 CFR

2014-10-01

... designed and used to take surfclams or ocean quahogs, provided that there is no retention of regulated...′ 70°00′ 1 Cape Cod shoreline on the Atlantic Ocean. (ii) Rolling Closure Area II. From April 1 through... Cape Cod Bay. 3 Cape Cod shoreline on the Atlantic Ocean. 4 New Hampshire shoreline. (iii) Rolling...

50 CFR 648.81 - NE multispecies closed areas and measures to protect EFH.

Code of Federal Regulations, 2013 CFR

2013-10-01

... designed and used to take surfclams or ocean quahogs, provided that there is no retention of regulated...′ 70°00′ 1 Cape Cod shoreline on the Atlantic Ocean. (ii) Rolling Closure Area II. From April 1 through... Cape Cod Bay. 3 Cape Cod shoreline on the Atlantic Ocean. 4 New Hampshire shoreline. (iii) Rolling...

Polymorphism, selection and tandem duplication of transferrin genes in Atlantic cod (Gadus morhua) - Conserved synteny between fish monolobal and tetrapod bilobal transferrin loci

PubMed Central

2011-01-01

Background The two homologous iron-binding lobes of transferrins are thought to have evolved by gene duplication of an ancestral monolobal form, but any conserved synteny between bilobal and monolobal transferrin loci remains unexplored. The important role played by transferrin in the resistance to invading pathogens makes this polymorphic gene a highly valuable candidate for studying adaptive divergence among local populations. Results The Atlantic cod genome was shown to harbour two tandem duplicated serum transferrin genes (Tf1, Tf2), a melanotransferrin gene (MTf), and a monolobal transferrin gene (Omp). Whereas Tf1 and Tf2 were differentially expressed in liver and brain, the Omp transcript was restricted to the otoliths. Fish, chicken and mammals showed highly conserved syntenic regions in which monolobal and bilobal transferrins reside, but contrasting with tetrapods, the fish transferrin genes are positioned on three different linkage groups. Sequence alignment of cod Tf1 cDNAs from Northeast (NE) and Northwest (NW) Atlantic populations revealed 22 single nucleotide polymorphisms (SNP) causing the replacement of 16 amino acids, including eight surface residues revealed by the modelled 3D-structures, that might influence the binding of pathogens for removal of iron. SNP analysis of a total of 375 individuals from 14 trans-Atlantic populations showed that the Tf1-NE variant was almost fixed in the Baltic cod and predominated in the other NE Atlantic populations, whereas the NW Atlantic populations were more heterozygous and showed high frequencies of the Tf-NW SNP alleles. Conclusions The highly conserved synteny between fish and tetrapod transferrin loci infers that the fusion of tandem duplicated Omp-like genes gave rise to the modern transferrins. The multiple nonsynonymous substitutions in cod Tf1 with putative structural effects, together with highly divergent allele frequencies among different cod populations, strongly suggest evidence for positive selection and local adaptation in trans-Atlantic cod populations. PMID:21612617

Polymorphism, selection and tandem duplication of transferrin genes in Atlantic cod (Gadus morhua)--conserved synteny between fish monolobal and tetrapod bilobal transferrin loci.

PubMed

Andersen, Øivind; De Rosa, Maria Cristina; Pirolli, Davide; Tooming-Klunderud, Ave; Petersen, Petra E; André, Carl

2011-05-25

The two homologous iron-binding lobes of transferrins are thought to have evolved by gene duplication of an ancestral monolobal form, but any conserved synteny between bilobal and monolobal transferrin loci remains unexplored. The important role played by transferrin in the resistance to invading pathogens makes this polymorphic gene a highly valuable candidate for studying adaptive divergence among local populations. The Atlantic cod genome was shown to harbour two tandem duplicated serum transferrin genes (Tf1, Tf2), a melanotransferrin gene (MTf), and a monolobal transferrin gene (Omp). Whereas Tf1 and Tf2 were differentially expressed in liver and brain, the Omp transcript was restricted to the otoliths. Fish, chicken and mammals showed highly conserved syntenic regions in which monolobal and bilobal transferrins reside, but contrasting with tetrapods, the fish transferrin genes are positioned on three different linkage groups. Sequence alignment of cod Tf1 cDNAs from Northeast (NE) and Northwest (NW) Atlantic populations revealed 22 single nucleotide polymorphisms (SNP) causing the replacement of 16 amino acids, including eight surface residues revealed by the modelled 3D-structures, that might influence the binding of pathogens for removal of iron. SNP analysis of a total of 375 individuals from 14 trans-Atlantic populations showed that the Tf1-NE variant was almost fixed in the Baltic cod and predominated in the other NE Atlantic populations, whereas the NW Atlantic populations were more heterozygous and showed high frequencies of the Tf-NW SNP alleles. The highly conserved synteny between fish and tetrapod transferrin loci infers that the fusion of tandem duplicated Omp-like genes gave rise to the modern transferrins. The multiple nonsynonymous substitutions in cod Tf1 with putative structural effects, together with highly divergent allele frequencies among different cod populations, strongly suggest evidence for positive selection and local adaptation in trans-Atlantic cod populations.

Spawning stock and recruitment in North Sea cod shaped by food and climate

PubMed Central

Olsen, Esben Moland; Ottersen, Geir; Llope, Marcos; Chan, Kung-Sik; Beaugrand, Grégory; Stenseth, Nils Chr.

2011-01-01

In order to provide better fisheries management and conservation decisions, there is a need to discern the underlying relationship between the spawning stock and recruitment of marine fishes, a relationship which is influenced by the environmental conditions. Here, we demonstrate how the environmental conditions (temperature and the food availability for fish larvae) influence the stock–recruitment relationship and indeed what kind of stock–recruitment relationship we might see under different environmental conditions. Using unique zooplankton data from the Continuous Plankton Recorder, we find that food availability (i.e. zooplankton) in essence determines which model applies for the once large North Sea cod (Gadus morhua) stock. Further, we show that recruitment is strengthened during cold years and weakened during warm years. Our combined model explained 45 per cent of the total variance in cod recruitment, while the traditional Ricker and Beverton–Holt models only explained about 10 per cent. Specifically, our approach predicts that a full recovery of the North Sea cod stock might not be expected until the environment becomes more favourable. PMID:20810442

Genomic analysis of the host response to nervous necrosis virus in Atlantic cod (Gadus morhua) brain.

PubMed

Krasnov, Aleksei; Kileng, Øyvind; Skugor, Stanko; Jørgensen, Sven Martin; Afanasyev, Sergey; Timmerhaus, Gerrit; Sommer, Ann-Inger; Jensen, Ingvill

2013-07-01

Genome sequencing combined with transcriptome profiling promotes exploration of defence against pathogens and discovery of immune genes. Based on sequences from the recently released genome of Atlantic cod, a genome-wide oligonucleotide microarray (ACIQ-1) was designed and used for analyses of gene expression in the brain during infection with nervous necrosis virus (NNV). A challenge experiment with NNV was performed with Atlantic cod juveniles and brain samples from virus infected and uninfected fish were used for microarray analysis. Expression of virus induced genes increased at 5 days post challenge and persisted at stable level to the last sampling at 25 days post challenge. A large fraction of the up-regulated genes (546 features) were known or expected to have immune functions and most of these have not previously been characterized in Atlantic cod. Transcriptomic changes induced by the virus involved strong activation of genes associated with interferon and tumour necrosis factor related responses and acute inflammation. Up-regulation of genes involved in adaptive immunity suggested a rapid recruitment of B and T lymphocytes to the NNV infected brain. QPCR analyses of 15 candidate genes of innate immunity showed rapid induction by poly(I:C) in Atlantic cod larvae cells suggesting an antiviral role. Earliest and greatest expression changes after poly I:C stimulation was observed for interferon regulatory factors IRF4 and IRF7. Comparative studies between teleost species provided new knowledge about the evolution of innate antiviral immunity in fish. A number of genes is present or responds to viruses only in fish. Innate immunity of Atlantic cod is characterized by selective expansion of several medium-sized multigene families with ribose binding domains. An interesting finding was the high representation of three large gene families among the early antiviral genes, including tripartite motif proteins (TRIM) and proteins with PRY-SPRY and NACHT domains. The latter two with respectively 52 and 114 members in Atlantic cod have gone through expansions in different groups of fish. These proteins most likely have ligand binding properties and their propagation could be linked to the loss of MHC class II in the Atlantic cod genome. Copyright © 2013 Elsevier Ltd. All rights reserved.

[Assessment of production of eggs of Eastern Baltic cod (Gadus morhua callarias L.) on the basis of long-term ichthyoplankton data].

PubMed

Karaseva, E M

2011-01-01

Proceeding from long-term data on the numbers of eggs of cod in ichthyoplankton, the total annual production of cod eggs at four main spawning grounds of the Baltic Sea was calculated. It was shown that the long-term fluctuations of cod egg production were positively related to the dynamics of the volume of waters coming to the Baltic Sea in years of the North Sea advections. It is suggested that this dependence was determined by a set of adaptations providing the extension of cod reproduction upon the improvement of the environment.

Ice-age survival of Atlantic cod: agreement between palaeoecology models and genetics

PubMed Central

Bigg, Grant R; Cunningham, Clifford W; Ottersen, Geir; Pogson, Grant H; Wadley, Martin R; Williamson, Phillip

2007-01-01

Scant scientific attention has been given to the abundance and distribution of marine biota in the face of the lower sea level, and steeper latitudinal gradient in climate, during the ice-age conditions that have dominated the past million years. Here we examine the glacial persistence of Atlantic cod (Gadus morhua) populations using two ecological-niche-models (ENM) and the first broad synthesis of multi-locus gene sequence data for this species. One ENM uses a maximum entropy approach (Maxent); the other is a new ENM for Atlantic cod, using ecophysiological parameters based on observed reproductive events rather than adult distribution. Both the ENMs were tested for present-day conditions, then used to hindcast ranges at the last glacial maximum (LGM) ca 21 kyr ago, employing climate model data. Although the LGM range of Atlantic cod was much smaller, and fragmented, both the ENMs agreed that populations should have been able to persist in suitable habitat on both sides of the Atlantic. The genetic results showed a degree of trans-Atlantic divergence consistent with genealogically continuous populations on both sides of the North Atlantic since long before the LGM, confirming the ENM results. In contrast, both the ENMs and the genetic data suggest that the Greenland G. morhua population post-dates the LGM. PMID:17999951

Residency, site fidelity and habitat use of Atlantic cod (Gadus morhua) at an offshore wind farm using acoustic telemetry.

PubMed

Reubens, Jan T; Pasotti, Francesca; Degraer, Steven; Vincx, Magda

2013-09-01

Because offshore wind energy development is fast growing in Europe it is important to investigate the changes in the marine environment and how these may influence local biodiversity and ecosystem functioning. One of the species affected by these ecosystem changes is Atlantic cod (Gadus morhua), a heavily exploited, commercially important fish species. In this research we investigated the residency, site fidelity and habitat use of Atlantic cod on a temporal scale at windmill artificial reefs in the Belgian part of the North Sea. Acoustic telemetry was used and the Vemco VR2W position system was deployed to quantify the movement behaviour. In total, 22 Atlantic cod were tagged and monitored for up to one year. Many fish were present near the artificial reefs during summer and autumn, and demonstrated strong residency and high individual detection rates. When present within the study area, Atlantic cod also showed distinct habitat selectivity. We identified aggregation near the artificial hard substrates of the wind turbines. In addition, a clear seasonal pattern in presence was observed. The high number of fish present in summer and autumn alternated with a period of very low densities during the winter period. Copyright © 2013 Elsevier Ltd. All rights reserved.

Random forests, a novel approach for discrimination of fish populations using parasites as biological tags.

PubMed

Perdiguero-Alonso, Diana; Montero, Francisco E; Kostadinova, Aneta; Raga, Juan Antonio; Barrett, John

2008-10-01

Due to the complexity of host-parasite relationships, discrimination between fish populations using parasites as biological tags is difficult. This study introduces, to our knowledge for the first time, random forests (RF) as a new modelling technique in the application of parasite community data as biological markers for population assignment of fish. This novel approach is applied to a dataset with a complex structure comprising 763 parasite infracommunities in population samples of Atlantic cod, Gadus morhua, from the spawning/feeding areas in five regions in the North East Atlantic (Baltic, Celtic, Irish and North seas and Icelandic waters). The learning behaviour of RF is evaluated in comparison with two other algorithms applied to class assignment problems, the linear discriminant function analysis (LDA) and artificial neural networks (ANN). The three algorithms are used to develop predictive models applying three cross-validation procedures in a series of experiments (252 models in total). The comparative approach to RF, LDA and ANN algorithms applied to the same datasets demonstrates the competitive potential of RF for developing predictive models since RF exhibited better accuracy of prediction and outperformed LDA and ANN in the assignment of fish to their regions of sampling using parasite community data. The comparative analyses and the validation experiment with a 'blind' sample confirmed that RF models performed more effectively with a large and diverse training set and a large number of variables. The discrimination results obtained for a migratory fish species with largely overlapping parasite communities reflects the high potential of RF for developing predictive models using data that are both complex and noisy, and indicates that it is a promising tool for parasite tag studies. Our results suggest that parasite community data can be used successfully to discriminate individual cod from the five different regions of the North East Atlantic studied using RF.

Evolutionary pressure on reproductive strategies in flatfish and groundfish: Relevant concepts and methodological advancements

NASA Astrophysics Data System (ADS)

Kjesbu, O. S.; Witthames, P. R.

2007-07-01

Flatfish and groundfish show many similarities in reproductive strategies and tactics, both in types present and in responses to fishing pressure or changes in their environment. Over the last 20-30 years the reproduction of Atlantic cod Gadus morhua, Atlantic halibut Hippoglossus hippoglossus, plaice Pleuronectes platessa, sole Solea solea, and turbot Scophthalmus maximus have been extensively studied in the North Atlantic. For cod, halibut and turbot, the research has progressed rapidly due to interest from the aquaculture industry. Extensive overexploitation over many years in combination with climate change represents a potential evolutionary pressure towards changes in growth, lower age at maturity, increased fecundity, smaller egg size (and thereby larval size) and change in spawning time. Early sexual maturity/precocious maturation is also seen in aquaculture and is problematic economically due to a reduction in fillet production. In this paper information is reviewed from studies on both wild and captive populations in experiments, the latter considered important because overexploitation, such as observed in the North Sea, often reduces the natural dynamics in growth and reproduction and complicates collection of sufficiently large samples. Evidence from laboratory experiments demonstrates the inherent plasticity of fecundity production and how this is controlled by food availability and length of photoperiod, while recent information from field studies demonstrates the evolution of genotypes in response to fishing mortality. Today several laboratories have adopted modern techniques for analysis of reproductive investments (fecundity, atresia and sperm characterisation) in controlled experimental situations to explore the effect of temperature or other environmental parameters (such as salinity) on reproduction. These developments, in combination with the rapid implementation of molecular techniques, should make it possible in the future to present highly precise information on reproductive potential, both at the individual and stock level. Of particular interest, and a major goal, would be to dissociate genetic and phenotypic control of reproductive traits arising from a better understanding of gene expression in captive populations.

A review of the contributions of fisheries and climate variability to contrasting dynamics in two Arcto-boreal Atlantic cod (Gadus morhua) stocks: Persistent high productivity in the Barents Sea and collapse on the Newfoundland and Labrador Shelf

NASA Astrophysics Data System (ADS)

Lilly, George R.; Nakken, Odd; Brattey, John

2013-07-01

Stocks of Atlantic cod (Gadus morhua) across the North Atlantic and adjacent seas have been fished intensively for years, and many are now severely depleted. In order to promote recovery and sustainable harvesting, it is essential to understand factors that have contributed to the declines and to variability in rates of recovery. Considerable insight may be gleaned by comparing and contrasting the histories of the Northeast Arctic (NEA) cod in the Barents Sea - Svalbard area of the northeast Atlantic and the “northern cod” on the Newfoundland and Labrador (NL) shelf in the northwest Atlantic. These two stocks, which were among the 3 largest cod stocks during the middle of the 20th century, are Arcto-boreal, and have many species of prey and predators in common. The biomass of NEA cod has varied considerably over time, and in 2009 was a little above 60% of its maximum observed level, which occurred in the late 1940s and early 1950s. In contrast, the biomass of NL cod decreased steadily from the early 1960s to the late 1970s, increased somewhat during the 1980s, and crashed during the early 1990s to an extremely low level, at which it remained for a decade before showing recent indications of improvement. Although both stocks were influenced by similar changes in harvesting strategies and environmental circumstances, both biotic and abiotic, there are two events which stand out as being particularly influential. First, crises developed in the management of both stocks in the late 1980s. For NEA cod, the crisis was environmental, caused by the collapse of capelin (Mallotus villosus), the main food for adult cod, whereas for NL cod the crisis was caused by a sudden large reduction in scientific perception of stock size. The difference in response to these crises strongly influenced subsequent stock dynamics. Catches of NEA cod were reduced considerably, preventing severe overharvesting of the cod that at that time experienced low productivity, whereas catches of NL cod were reduced only a little, contributing to escalating fishing mortality. The second event followed directly upon the first. The North Atlantic Oscillation index, which had been increasingly positive since the early 1970s, became strongly so during the early 1990s, creating favourable environmental conditions (warm water) in the Barents Sea and highly unfavourable conditions (cold water and extensive ice cover) on the Newfoundland-Labrador Shelf. The NEA stock recovered quickly, whereas the NL stock collapsed. The NEA cod has remained highly productive to this date, whereas the NL cod remained very unproductive for a decade, primarily because of high mortality, most of which appears to have been natural.

EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON THE REGULATION OF THE ONSET OF MATURATION IN THE ESTUARINE FISH MENIDIA BERYLLINA (COPE) (ATHERINIDAE)

EPA Science Inventory

Menidia beryllina (Cope) is an annual species that inhabits coastal estuaries along the east coast of the United States from Cape Cod to the Gulf of Mexico. In Rhode Island, USA, its peak spawning time and the duration of the spawning vary among years and estuaries. However, the ...

Adaptation to Low Salinity Promotes Genomic Divergence in Atlantic Cod (Gadus morhua L.)

PubMed Central

Berg, Paul R.; Jentoft, Sissel; Star, Bastiaan; Ring, Kristoffer H.; Knutsen, Halvor; Lien, Sigbjørn; Jakobsen, Kjetill S.; André, Carl

2015-01-01

How genomic selection enables species to adapt to divergent environments is a fundamental question in ecology and evolution. We investigated the genomic signatures of local adaptation in Atlantic cod (Gadus morhua L.) along a natural salinity gradient, ranging from 35‰ in the North Sea to 7‰ within the Baltic Sea. By utilizing a 12 K SNPchip, we simultaneously assessed neutral and adaptive genetic divergence across the Atlantic cod genome. Combining outlier analyses with a landscape genomic approach, we identified a set of directionally selected loci that are strongly correlated with habitat differences in salinity, oxygen, and temperature. Our results show that discrete regions within the Atlantic cod genome are subject to directional selection and associated with adaptation to the local environmental conditions in the Baltic- and the North Sea, indicating divergence hitchhiking and the presence of genomic islands of divergence. We report a suite of outlier single nucleotide polymorphisms within or closely located to genes associated with osmoregulation, as well as genes known to play important roles in the hydration and development of oocytes. These genes are likely to have key functions within a general osmoregulatory framework and are important for the survival of eggs and larvae, contributing to the buildup of reproductive isolation between the low-salinity adapted Baltic cod and the adjacent cod populations. Hence, our data suggest that adaptive responses to the environmental conditions in the Baltic Sea may contribute to a strong and effective reproductive barrier, and that Baltic cod can be viewed as an example of ongoing speciation. PMID:25994933

Quantifying overlap between the Deepwater Horizon oil spill and predicted bluefin tuna spawning habitat in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Hazen, Elliott L.; Carlisle, Aaron B.; Wilson, Steven G.; Ganong, James E.; Castleton, Michael R.; Schallert, Robert J.; Stokesbury, Michael J. W.; Bograd, Steven J.; Block, Barbara A.

2016-09-01

Atlantic bluefin tuna (Thunnus thynnus) are distributed throughout the North Atlantic and are both economically valuable and heavily exploited. The fishery is currently managed as two spawning populations, with the GOM population being severely depleted for over 20 years. In April-August of 2010, the Deepwater Horizon oil spill released approximately 4 million barrels of oil into the GOM, with severe ecosystem and economic impacts. Acute oil exposure results in mortality of bluefin eggs and larvae, while chronic effects on spawning adults are less well understood. Here we used 16 years of electronic tagging data for 66 bluefin tuna to identify spawning events, to quantify habitat preferences, and to predict habitat use and oil exposure within Gulf of Mexico spawning grounds. More than 54,000 km2 (5%) of predicted spawning habitat within the US EEZ was oiled during the week of peak oil dispersal, with potentially lethal effects on eggs and larvae. Although the oil spill overlapped with a relatively small portion of predicted spawning habitat, the cumulative impact from oil, ocean warming and bycatch mortality on GOM spawning grounds may result in significant effects for a population that shows little evidence of rebuilding.

Optimized conditions for primary culture of pituitary cells from the Atlantic cod (Gadus morhua). The importance of osmolality, pCO₂, and pH.

PubMed

Hodne, Kjetil; von Krogh, Kristine; Weltzien, Finn-Arne; Sand, Olav; Haug, Trude M

2012-09-01

Protocols for primary cultures of teleost cells are commonly only moderately adjusted from similar protocols for mammalian cells, the main adjustment often being of temperature. Because aquatic habitats are in general colder than mammalian body temperatures and teleosts have gills in direct contact with water, pH and buffer capacity of blood and extracellular fluid are different in fish and mammals. Plasma osmolality is generally higher in marine teleosts than in mammals. Using Atlantic cod (Gadus morhua) as a model, we have optimized these physiological parameters to maintain primary pituitary cells in culture for an extended period without loosing key properties. L-15 medium with adjusted osmolality, adapted to low pCO(2) (3.8mm Hg) and temperature (12°C), and with pH 7.85, maintained the cells in a physiologically sounder state than traditional culture medium, significantly improving cell viability compared to the initial protocol. In the optimized culture medium, resting membrane potential and response to releasing hormone were stable for at least two weeks, and the proportion of cells firing action potentials during spawning season was about seven times higher than in the original culture medium. The cells were moderately more viable when the modified medium was supplemented with newborn calf serum or artificial serum substitute. Compared to serum-free L-15 medium, expression of key genes (lhb, fshb, and gnrhr2a) was better maintained in medium containing SSR, whereas NCS tended to decrease the expression level. Although serum-free medium is adequate for many applications, serum supplement may be preferable for experiments dependent on membrane integrity. Copyright © 2012 Elsevier Inc. All rights reserved.

An improved genome assembly uncovers prolific tandem repeats in Atlantic cod.

PubMed

Tørresen, Ole K; Star, Bastiaan; Jentoft, Sissel; Reinar, William B; Grove, Harald; Miller, Jason R; Walenz, Brian P; Knight, James; Ekholm, Jenny M; Peluso, Paul; Edvardsen, Rolf B; Tooming-Klunderud, Ave; Skage, Morten; Lien, Sigbjørn; Jakobsen, Kjetill S; Nederbragt, Alexander J

2017-01-18

The first Atlantic cod (Gadus morhua) genome assembly published in 2011 was one of the early genome assemblies exclusively based on high-throughput 454 pyrosequencing. Since then, rapid advances in sequencing technologies have led to a multitude of assemblies generated for complex genomes, although many of these are of a fragmented nature with a significant fraction of bases in gaps. The development of long-read sequencing and improved software now enable the generation of more contiguous genome assemblies. By combining data from Illumina, 454 and the longer PacBio sequencing technologies, as well as integrating the results of multiple assembly programs, we have created a substantially improved version of the Atlantic cod genome assembly. The sequence contiguity of this assembly is increased fifty-fold and the proportion of gap-bases has been reduced fifteen-fold. Compared to other vertebrates, the assembly contains an unusual high density of tandem repeats (TRs). Indeed, retrospective analyses reveal that gaps in the first genome assembly were largely associated with these TRs. We show that 21% of the TRs across the assembly, 19% in the promoter regions and 12% in the coding sequences are heterozygous in the sequenced individual. The inclusion of PacBio reads combined with the use of multiple assembly programs drastically improved the Atlantic cod genome assembly by successfully resolving long TRs. The high frequency of heterozygous TRs within or in the vicinity of genes in the genome indicate a considerable standing genomic variation in Atlantic cod populations, which is likely of evolutionary importance.

Effects of hydropeaking on the spawning behaviour of Atlantic salmon Salmo salar and brown trout Salmo trutta.

PubMed

Vollset, K W; Skoglund, H; Wiers, T; Barlaup, B T

2016-06-01

An in situ camera set-up was used to study the spawning activity of Atlantic salmon Salmo salar and brown trout Salmo trutta throughout two consecutive seasons in a spawning area affected by hydropower-related pulse flows due to hydropeaking. The purpose was to test whether the flow variation discouraged spawning in shallow areas or motivated spawning into areas with elevated risk of incubation mortality. There were more S. salar observed on the spawning ground during days with high discharge. The presence of S. salar in the spawning grounds was not affected by the hydropeaking cycles of the preceding night. Female S. salar were observed preparing nests within the first hour after water discharge had increased to levels suitable for spawning. In contrast, the number of S. trutta was not correlated with flow and nest preparation was also observed at a discharge corresponding to the lowest discharge levels during a hydropeaking cycle. Survival was generally high in nests excavated the following winter, with only 5·4% suffering mortality due to dewatering. The results suggest that S. salar may respond rapidly to variable-flow conditions and utilize short windows with suitable flows for spawning. Smaller S. trutta may utilize low-flow conditions to spawn in areas that are not habitable by larger S. salar during low flow. © 2016 The Fisheries Society of the British Isles.

Reproductive performance of alternative male phenotypes of growth hormone transgenic Atlantic salmon (Salmo salar)

PubMed Central

Moreau, Darek T R; Conway, Corinne; Fleming, Ian A

2011-01-01

Growth hormone (GH) transgenic Atlantic salmon (Salmo salar) is one of the first transgenic animals being considered for commercial farming, yet ecological and genetic concerns remain should they enter the wild and interact reproductively with wild fish. Here, we provide the first empirical data reporting on the breeding performance of GH transgenic Atlantic salmon males, including that of an alternative male reproductive phenotype (i.e. small, precocially mature parr), in pair-wise competitive trials within a naturalised stream mesocosm. Wild anadromous (i.e. large, migratory) males outperformed captively reared transgenic counterparts in terms of nest fidelity, quivering frequency and spawn participation. Similarly, despite displaying less aggression, captively reared nontransgenic mature parr were superior competitors to their transgenic counterparts in terms of nest fidelity and spawn participation. Moreover, nontransgenic parr had higher overall fertilisation success than transgenic parr, and their offspring were represented in more spawning trials. Although transgenic males displayed reduced breeding performance relative to nontransgenics, both male reproductive phenotypes demonstrated the ability to participate in natural spawning events and thus have the potential to contribute genes to subsequent generations. PMID:25568019

Precision-cut liver slices of Atlantic cod (Gadus morhua): an in vitro system for studying the effects of environmental contaminants.

PubMed

Eide, M; Karlsen, O A; Kryvi, H; Olsvik, P A; Goksøyr, A

2014-08-01

The Atlantic cod (Gadus morhua) is an economically important species commonly consumed by humans. The widespread distribution of cod in the North Atlantic Ocean makes it vulnerable to effluents from human activities, such as coastal industries and offshore petroleum exploration. It has been demonstrated that many effluents have adverse effects on cod reproduction and health, e.g. by disrupting endocrine signaling pathways. The liver, expressing important components of the biotransformation and the endocrine system, is one of the main target organs. Thus, reliable and reproducible in vitro systems of the liver are important for studying effects of environmental contaminants. The aim of this study was to investigate precision-cut liver slices (PCLS) as an alternative in vitro system for toxicological studies of the Atlantic cod liver. Slices of 8 mm in diameter and 250 μm thickness were prepared and cultivated from immature cod. Several analyses to measure the liver slice viability were performed: enzyme assays, histology, and morphometric analysis, all confirming cell viability for up to 72 h in culture. The liver slices were also exposed to two well-known model environmental contaminants, β-naphthoflavone (BNF) and 17α-ethynylestradiol (EE2), representing established agonists for the aryl hydrocarbon receptor (AHR) and the estrogen receptor (ER), respectively. The results showed increased transcription of the target genes cytochrome P450 1A (CYP1A) and vitellogenin (VTG), both well-established biomarkers for exposure of fish to the selected compounds. In conclusion, PCLS is a promising in vitro system for toxicological studies of cod liver cells. The liver slices are viable in culture for several days and respond to environmental contaminants in a dose- and time-specific manner. Copyright © 2013 Elsevier B.V. All rights reserved.

Movements of Atlantic Sturgeon of the Gulf of Maine inside and outside the geographically defined Distinct Population Segment

USGS Publications Warehouse

Wippelhauser, Gail S.; Sulikowski, James; Zydlewski, Gayle B.; Altenritter, Megan; Kieffer, Micah; Kinnison, Michael T.

2017-01-01

Identification of potential critical habitat, seasonal distributions, and movements within and between river systems is important for protecting the Gulf of Maine (GOM) Distinct Population Segment of Atlantic Sturgeon. To accomplish these objectives, we captured Atlantic Sturgeon in four GOM rivers (Penobscot, Kennebec system, Saco, and Merrimack), and tagged 144 (83.3–217.4 cm TL) internally with uniquely coded acoustic transmitters. Tagged fish were detected between 2006 to 2014 by primary receiver arrays deployed in the four GOM rivers or opportunistically on a secondary group of receivers deployed within the GOM and along the continental shelf. Atlantic Sturgeon tagged in the four rivers were documented at three spawning areas in the Kennebec system in June and July, including one that became accessible in 1999 when the Edwards Dam was removed. After being tagged, the majority (74%) of Atlantic sturgeon were detected in the estuaries of the four GOM rivers, primarily from May through October. Tagged fish spent most of their time in saline water in the Saco River and Merrimack River, moved into brackish water in the Penobscot River, and were found in saline, brackish, and fresh water in the Kennebec system. Approximately 70% of the tagged fish were detected in GOM coastal waters, and aggregated in the Bay of Fundy (May–January), offshore of the Penobscot River (September-February and May), offshore of the Kennebec River (September–February), in Saco Bay and the Scarborough River (July–November), and along the eastern Massachusetts coast between Cape Ann and Cape Cod (April–February). Nine tagged Atlantic sturgeon (7%) left the GOM, three of which moved as far north as Halifax in Canada and six moved as far south as the James River in Virginia. Information from this study will be used to make recommendations to avoid, reduce or mitigate the impacts of in-water projects and on Atlantic sturgeon.

Genetic and morphological variation in Echinorhynchus gadi Zoega in Müller, 1776 (Acanthocephala: Echinorhynchidae) from Atlantic cod Gadus morhua L.

PubMed

Sobecka, E; Szostakowska, B; MacKenzie, K; Hemmingsen, W; Prajsnar, S; Eydal, M

2012-03-01

Previous studies have shown considerable variability in morphological features and the existence of genetically distinct sibling species in the acanthocephalan Echinorhynchus gadi Zoega in Müller, 1776. The aim of the present study was to follow up and extend those earlier studies by using a combination of DNA analysis and morphometrics to investigate differences between samples of E. gadi from Atlantic cod Gadus morhua L. caught at five fishing grounds in the Baltic Sea and three in different parts of the North Atlantic. Twelve morphological features were measured in 431 specimens of E. gadi, 99 individuals were studied by polymerase chain reaction-restriction fragment length polymorphosm (PCR-RFLP), and selected PCR products were sequenced. The molecular analyses showed the nucleotide sequences of E. gadi rDNA from cod caught at all the sampling sites to be identical. The comparative morphological study, in contrast, revealed significant differences between samples of E. gadi from different sampling sites and showed the separation of E. gadi into two groups corresponding approximately to the systematic classification of cod into the two subspecies, Atlantic G. morhua morhua and Baltic G. morhua callarias. The E. gadi infrapopulation size had a significant effect on some of the morphological features. The results are discussed in relation to cod population biology, the hydrography of the study area and the history of the Baltic Sea formation.

EST resources and establishment and validation of a 16k cDNA microarray from Atlantic cod (Gadus morhua).

PubMed

Edvardsen, Rolf B; Malde, Ketil; Mittelholzer, Christian; Taranger, Geir Lasse; Nilsen, Frank

2011-03-01

The Atlantic cod, Gadus morhua, is an important species both for traditional fishery and increasingly also in fish farming. The Atlantic cod is also under potential threat from various environmental changes such as pollution and climate change, but the biological impact of such changes are not well known, in particular when it comes to sublethal effects that can be difficult to assert. Modern molecular and genomic approaches have revolutionized biological research during the last decade, and offer new avenues to study biological functions and e.g. the impact of anthropogenic activities at different life-stages for a given organism. In order to develop genomic data and genomic tools for Atlantic cod we conducted a program were we constructed 20 cDNA libraries, and produced and analyzed 44006 expressed sequence tags (ESTs) from these. Several tissues are represented in the multiple cDNA libraries, that differ in either sexual maturation or immulogical stimulation. This approach allowed us to identify genes that are expressed in particular tissues, life-stages or in response to specific stimuli, and also gives us information about potential functions of the transcripts. The ESTs were used to construct a 16k cDNA microarray to further investigate the cod transcriptome. Microarray analyses were preformed on pylorus, pituitary gland, spleen and testis of sexually maturing male cod. The four different tissues displayed tissue specific transcriptomes demonstrating that the cDNA array is working as expected and will prove to be a powerful tool in further experiments. Copyright © 2010 Elsevier Inc. All rights reserved.

Viral hemorrhagic septicemia virus in North America

USGS Publications Warehouse

Meyers, Theodore R.; Winton, James R.

1995-01-01

The first detections of viral hemorrhagic septicemia virus (VHSV) in North America were in Washington State from adult coho (Oncorhynchus kisutch) and chinook (O. tshawytscha) salmon in 1988. Subsequently, VHSV was isolated from adult coho salmon returning to hatcheries in the Pacific Northwest in 1989, 1991 and 1994. These isolates represented a strain of VHSV that was genetically different from European VHSV as determined by DNA sequence analysis and T1 ribonuclease fingerprinting. The North American strain of VHSV was also isolated from skin lesions of Pacific cod (Gadus macrocephalus) taken from Prince William Sound (PWS), Alaska in 1990, 1991 and 1993. In 1993 and 1994, the virus was isolated from Pacific herring (Clupea harengus pallasi) in Alaskan waters of PWS, Kodiak Island, Auke Bay and Port Frederick. During 1993 and 1994 the herring fishery in PWS failed from a probable complex of environmental stressors but VHSV isolates were associated with hemorrhages of the skin and fins in fish that returned to spawn. Also in 1993 and 1994, VHSV was isolated from apparently healthy stocks of herring in British Columbia, Canada and Puget Sound, Washington. Thus, the North American strain of VHSV is enzootic in the Northeastern Pacific Ocean among Pacific herring stocks with Pacific cod serving as a secondary reservoir. Although the North American strain of the virus appears to be moderately pathogenic for herring, causing occasional self-limiting epizootics, it was shown to be relatively avirulent for several species of salmonids. Pacific herring are common prey for cod and salmon and were most probably the source of the VHSV isolates from the adult salmon returning to spawn in rivers or at hatcheries in Washington State. Compelling circumstances involving the European isolates of VHSV suggest that this strain of the virus also is enzootic among marine fish in the Atlantic Oean. The highly pathogenic nature of the European strain of VHSV for salmonid fish may be the result of the exposure of rainbow trout (O. mykiss), an introduced species, in a stressful environment of intensive culture and the high rate of mutation inherent in all rhabdoviruses. Consequently, we recommend that efforts be made to eradicate the North American strain of VHSV when detected in live salmonids to reduce the possibility of its evolution into a more virulent salmonid virus.

The impact of a moderate chronic temperature increase on spleen immune-relevant gene transcription depends on whether Atlantic cod (Gadus morhua) are stimulated with bacterial versus viral antigens.

PubMed

Hori, Tiago S; Gamperl, A Kurt; Nash, Gord; Booman, Marije; Barat, Ashoktaru; Rise, Matthew L

2013-10-01

Exposure to elevated temperature is an inherent feature of Atlantic cod (Gadus morhua) sea-cage culture in some regions (e.g., Newfoundland) and may also become an increasingly prevalent challenge for wild fish populations because of accelerated climate change. Therefore, understanding how elevated temperatures impacts the immune response of this commercially important species may help to reduce the potential negative impacts of such challenges. Previously, we investigated the impacts of moderately elevated temperature on the antiviral responses of Atlantic cod (Hori et al. 2012) and reported that elevated temperature modulated the spleen transcriptome response to polyriboinosinic polyribocytidylic acid (pIC, a viral mimic). Herein, we report a complementary microarray study that investigated the impact of the same elevated temperature regime on the Atlantic cod spleen transcriptome response to intraperitoneal (IP) injection of formalin-killed Aeromonas salmonicida (ASAL). Fish were held at two different temperatures (10 °C and 16 °C) prior to immune stimulation and sampled 6 and 24 h post-injection (HPI). In this experiment, we identified 711 and 666 nonredundant ASAL-responsive genes at 6HPI and 24HPI, respectively. These included several known antibacterial genes, including hepcidin, cathelicidin, ferritin heavy subunit, and interleukin 8. However, we only identified 15 differentially expressed genes at 6HPI and 2 at 24HPI (FDR 1%) when comparing ASAL-injected fish held at 10 °C versus 16 °C. In contrast, the same comparisons with pIC-injected fish yielded 290 and 339 differentially expressed genes (FDR 1%) at 6HPI and 24HPI, respectively. These results suggest that moderately elevated temperature has a lesser effect on the Atlantic cod spleen transcriptome response to ASAL (i.e., the antibacterial response) than to pIC (i.e., antiviral response). Thus, the impacts of high temperatures on the cod's immune response may be pathogen dependent.

Spawning strategy in Atlantic bobtail squid Sepiola atlantica (Cephalopoda: Sepiolidae)

NASA Astrophysics Data System (ADS)

Rodrigues, Marcelo; Garcí, Manuel E.; Troncoso, Jesús S.; Guerra, Ángel

2011-03-01

This study aimed to determine the spawning strategy in the Atlantic bobtail squid Sepiola atlantica, in order to add new information to the knowledge of its reproductive strategy. A total of 12 females that spawned in aquaria were examined. Characteristics of the reproductive traits and egg clutches were similar to those of other known Sepiolidae. Clutch size varied from 31 up to 115 eggs. Females of this species had incorporated up to 1.58 times of their body weight into laid eggs. The size of laid eggs showed a positive correlation with maternal body size, supporting the idea that female size is a determinant of egg size. Our data suggest that S. atlantica is an intermittent terminal spawner , and that its spawning strategy comprises group-synchronous ovary maturation, multiple egg laying, and deposition of egg clutches in different locations. The obtained data provide insights for future comparative studies on reproductive allocation.

Habitat suitability of the Atlantic bluefin tuna by size class: An ecological niche approach

NASA Astrophysics Data System (ADS)

Druon, Jean-Noël; Fromentin, Jean-Marc; Hanke, Alex R.; Arrizabalaga, Haritz; Damalas, Dimitrios; Tičina, Vjekoslav; Quílez-Badia, Gemma; Ramirez, Karina; Arregui, Igor; Tserpes, George; Reglero, Patricia; Deflorio, Michele; Oray, Isik; Saadet Karakulak, F.; Megalofonou, Persefoni; Ceyhan, Tevfik; Grubišić, Leon; MacKenzie, Brian R.; Lamkin, John; Afonso, Pedro; Addis, Piero

2016-03-01

An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25 kg, only feeding) and large (>25 kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern - high chlorophyll levels - latitudes up to the Norwegian Sea in the eastern Atlantic and to the Gulf of Saint Lawrence in the western basin. Permanent suitable feeding habitat for small ABFT was predicted to be mostly located in temperate latitudes in the North Atlantic and in the Mediterranean Sea, as well as in subtropical waters off north-west Africa, while summer potential habitat in the Gulf of Mexico was found to be unsuitable for both small and large ABFTs. Potential spawning grounds were found to occur in the Gulf of Mexico from March-April in the south-east to April-May in the north, while favourable conditions evolve in the Mediterranean Sea from mid-May in the eastern to mid-July in the western basin. Other secondary potential spawning grounds not supported by observations were predicted in the Azores area and off Morocco to Senegal during July and August when extrapolating the model settings from the Gulf of Mexico into the North Atlantic. The presence of large ABFT off Florida and the Bahamas in spring was not explained by the model as is, however the environmental variables other than the sea surface height anomaly appeared to be favourable for spawning in part of this area. Defining key spatial and temporal habitats should further help in building spatially-explicit stock assessment models, thus improving the spatial management of bluefin tuna fisheries.

Calcium from salmon and cod bone is well absorbed in young healthy men: a double-blinded randomised crossover design.

PubMed

Malde, Marian K; Bügel, Susanne; Kristensen, Mette; Malde, Ketil; Graff, Ingvild E; Pedersen, Jan I

2010-07-20

Calcium (Ca) - fortified foods are likely to play an important role in helping the consumer achieve an adequate Ca intake, especially for persons with a low intake of dairy products. Fish bones have a high Ca content, and huge quantities of this raw material are available as a by-product from the fish industry. Previously, emphasis has been on producing high quality products from fish by-products by use of bacterial proteases. However, documentation of the nutritional value of the enzymatically rinsed Ca-rich bone fraction remains unexplored. The objective of the present study was to assess the bioavailability of calcium in bones of Atlantic salmon (oily fish) and Atlantic cod (lean fish) in a double-blinded randomised crossover design. Ca absorption was measured in 10 healthy young men using 47Ca whole body counting after ingestion of a test meal extrinsically labelled with the 47Ca isotope. The three test meals contained 800 mg of Ca from three different calcium sources: cod bones, salmon bones and control (CaCO3). Mean Ca absorption (+/- SEE) from the three different Ca sources were 21.9 +/- 1.7%, 22.5 +/- 1.7% and 27.4 +/- 1.8% for cod bones, salmon bones, and control (CaCO3), respectively. We conclude that bones from Atlantic salmon and Atlantic cod are suitable as natural Ca sources in e.g. functional foods or as supplements.

Calcium from salmon and cod bone is well absorbed in young healthy men: a double-blinded randomised crossover design

PubMed Central

2010-01-01

Background Calcium (Ca) - fortified foods are likely to play an important role in helping the consumer achieve an adequate Ca intake, especially for persons with a low intake of dairy products. Fish bones have a high Ca content, and huge quantities of this raw material are available as a by-product from the fish industry. Previously, emphasis has been on producing high quality products from fish by-products by use of bacterial proteases. However, documentation of the nutritional value of the enzymatically rinsed Ca-rich bone fraction remains unexplored. The objective of the present study was to assess the bioavailability of calcium in bones of Atlantic salmon (oily fish) and Atlantic cod (lean fish) in a double-blinded randomised crossover design. Methods Ca absorption was measured in 10 healthy young men using 47Ca whole body counting after ingestion of a test meal extrinsically labelled with the 47Ca isotope. The three test meals contained 800 mg of Ca from three different calcium sources: cod bones, salmon bones and control (CaCO3). Results Mean Ca absorption (± SEE) from the three different Ca sources were 21.9 ± 1.7%, 22.5 ± 1.7% and 27.4 ± 1.8% for cod bones, salmon bones, and control (CaCO3), respectively. Conclusion We conclude that bones from Atlantic salmon and Atlantic cod are suitable as natural Ca sources in e.g. functional foods or as supplements. PMID:20646299

Ocean Acidification Portends Acute Habitat Compression for Atlantic Cod (Gadus morhua) in a Physiologically-informed Metabolic Rate Model

NASA Astrophysics Data System (ADS)

Del Raye, G.; Weng, K.

2011-12-01

Ocean acidification affects organisms on a biochemical scale, yet its societal impacts manifest from changes that propagate through entire populations. Successful forecasting of the effects of ocean acidification therefore depends on at least two steps: (1) deducing systemic physiology based on subcellular stresses and (2) scaling individual physiology up to ecosystem processes. Predictions that are based on known biological processes (process-based models) may fare better than purely statistical models in both these steps because the latter are less robust to novel environmental conditions. Here we present a process-based model that uses temperature, pO2, and pCO2 to predict maximal aerobic scope in Atlantic cod. Using this model, we show that (i) experimentally-derived physiological parameters are sufficient to capture the response of cod aerobic scope to temperature and oxygen, and (ii) subcellular pH effects can be used to predict the systemic physiological response of cod to an acidified ocean. We predict that acute pH stress (on a scale of hours) could limit the mobility of Atlantic cod during diel vertical migration across a pCO2 gradient, promoting habitat compression. Finally, we use a global sensitivity analysis to identify opportunities for the improvement of model uncertainty as well as some physiological adaptations that could mitigate climate stresses on cod in the future.

The pre-spawning migratory behaviour of Atlantic salmon Salmo salar in a large lacustrine catchment.

PubMed

Kennedy, R J; Allen, M

2016-09-01

The movements of adult Atlantic salmon Salmo salar were determined as they migrated to spawning habitats in a large lacustrine catchment, Lough Neagh, in Northern Ireland. The minimum average ground speed of S. salar through the lake was 2·1 km day(-1) and the mean residence time was 11 days. Tagged S. salar tended to actively migrate through the lake which represented a transitory habitat for adult S. salar. Migration time from the release site, through the lake, to a spawning tributary decreased during the migratory period. During the 4 year study period between 20·5 and 41·6% of tagged S. salar which entered the lake each year, explored at least one other channel before ascending the final spawning tributary. Exploratory behaviour was more likely in S. salar which spawned in the tributaries furthest from the sea. Exploratory behaviour was also more likely to occur during periods of reduced discharge in the natal stream. The fishery management implications of complex pre-spawning behaviour in a mixed stock lacustrine system, are discussed. © 2016 The Fisheries Society of the British Isles.

Don't bet against the natal homing abilities of marine fishes.

PubMed

Bentzen, Paul; Bradbury, Ian R

2016-06-01

Whether marine fishes are capable of homing to their natal areas has long been something of an enigma. For some estuarine species or sharks (which have extended nondispersal juvenile stages or are born as relatively large, fully formed juveniles), the answer is clearly 'yes' (Thorrold et al. ; Feldheim et al. ), but for most marine fishes, the issue is much more mysterious. Many species have free-floating eggs, and most have pelagic, passively dispersing larvae. It is challenging to imagine how adult fish might navigate to a region of the ocean they experienced only as eggs or larvae, and easier to assume that such dispersal leads inexorably to high gene flow, and even panmixia. One way to resolve the conundrum would be to track fish from hatching to reproduction, but for marine fishes with tiny eggs and drifting larvae, this is notoriously difficult to do (Bradbury & Laurel ). In this issue of Molecular Ecology, Bonanomi et al. () use a creative approach to solve this challenge for Atlantic cod (Gadus morhua) populations that mingle in the vicinity of Greenland. They show that cod that disperse more than a 1000 km away from Iceland as eggs and larvae, then spend years growing on the far side of Greenland, while mixing with two local populations, return as adults to spawning areas near Iceland - and further, that this behaviour has remained stable over more than six decades. They manage this feat with a clever use of historical cod tracking data, modern genomic data and genetic analysis of decades-old DNA obtained from archived materials. Their results have important implications for our view of the biocomplexity of marine fish populations, and how we should manage them. © 2016 John Wiley & Sons Ltd.

Real-time ichthyoplankton drift in Northeast Arctic cod and Norwegian spring-spawning herring.

PubMed

Vikebø, Frode B; Ådlandsvik, Bjørn; Albretsen, Jon; Sundby, Svein; Stenevik, Erling Kåre; Huse, Geir; Svendsen, Einar; Kristiansen, Trond; Eriksen, Elena

2011-01-01

Individual-based biophysical larval models, initialized and parameterized by observations, enable numerical investigations of various factors regulating survival of young fish until they recruit into the adult population. Exponentially decreasing numbers in Northeast Arctic cod and Norwegian Spring Spawning herring early changes emphasizes the importance of early life history, when ichthyoplankton exhibit pelagic free drift. However, while most studies are concerned with past recruitment variability it is also important to establish real-time predictions of ichthyoplankton distributions due to the increasing human activity in fish habitats and the need for distribution predictions that could potentially improve field coverage of ichthyoplankton. A system has been developed for operational simulation of ichthyoplankton distributions. We have coupled a two-day ocean forecasts from the Norwegian Meteorological Institute with an individual-based ichthyoplankton model for Northeast Arctic cod and Norwegian Spring Spawning herring producing daily updated maps of ichthyoplankton distributions. Recent years observed spawning distribution and intensity have been used as input to the model system. The system has been running in an operational mode since 2008. Surveys are expensive and distributions of early stages are therefore only covered once or twice a year. Comparison between model and observations are therefore limited in time. However, the observed and simulated distributions of juvenile fish tend to agree well during early fall. Area-overlap between modeled and observed juveniles September 1(st) range from 61 to 73%, and 61 to 71% when weighted by concentrations. The model system may be used to evaluate the design of ongoing surveys, to quantify the overlap with harmful substances in the ocean after accidental spills, as well as management planning of particular risky operations at sea. The modeled distributions are already utilized during research surveys to estimate coverage success of sampled biota and immediately after spills from ships at sea.

Real-Time Ichthyoplankton Drift in Northeast Arctic Cod and Norwegian Spring-Spawning Herring

PubMed Central

Vikebø, Frode B.; Ådlandsvik, Bjørn; Albretsen, Jon; Sundby, Svein; Stenevik, Erling Kåre; Huse, Geir; Svendsen, Einar; Kristiansen, Trond; Eriksen, Elena

2011-01-01

Background Individual-based biophysical larval models, initialized and parameterized by observations, enable numerical investigations of various factors regulating survival of young fish until they recruit into the adult population. Exponentially decreasing numbers in Northeast Arctic cod and Norwegian Spring Spawning herring early changes emphasizes the importance of early life history, when ichthyoplankton exhibit pelagic free drift. However, while most studies are concerned with past recruitment variability it is also important to establish real-time predictions of ichthyoplankton distributions due to the increasing human activity in fish habitats and the need for distribution predictions that could potentially improve field coverage of ichthyoplankton. Methodology/Principal Findings A system has been developed for operational simulation of ichthyoplankton distributions. We have coupled a two-day ocean forecasts from the Norwegian Meteorological Institute with an individual-based ichthyoplankton model for Northeast Arctic cod and Norwegian Spring Spawning herring producing daily updated maps of ichthyoplankton distributions. Recent years observed spawning distribution and intensity have been used as input to the model system. The system has been running in an operational mode since 2008. Surveys are expensive and distributions of early stages are therefore only covered once or twice a year. Comparison between model and observations are therefore limited in time. However, the observed and simulated distributions of juvenile fish tend to agree well during early fall. Area-overlap between modeled and observed juveniles September 1st range from 61 to 73%, and 61 to 71% when weighted by concentrations. Conclusions/Significance The model system may be used to evaluate the design of ongoing surveys, to quantify the overlap with harmful substances in the ocean after accidental spills, as well as management planning of particular risky operations at sea. The modeled distributions are already utilized during research surveys to estimate coverage success of sampled biota and immediately after spills from ships at sea. PMID:22110633

Compounds of parasitic roundworm absorbing in the visible region: target molecules for detection of roundworm in Atlantic cod.

PubMed

Stormo, Svein K; Ernstsen, Arild; Nilsen, Heidi; Heia, Karsten; Sivertsen, Agnar H; Elvevoll, Edel

2004-07-01

The objective of this study was to contribute to the development of technology that will be able to replace manual operations in processing of fish fillets. Removal of parasites, black lining, remnants of skin, and bloodstains are costly and time-consuming operations to the fish processing industry. The presence of parasites in fish products tends to spoil consumers' appetites. Recent reports questioning the safety of eating cod infected with parasites might lower consumer acceptance of seafood. Presently, parasites are detected and removed manually. An average efficiency of about 75% under commercial conditions has been reported. In this study, we focused on biochemical differences between cod muscle and the prevalent anisakine nematode species (Anisakis simplex and Pseudoterranova decipiens) infecting Atlantic cod (Gadus morhua). Using reversed phase high-performance liquid chromatography equipped with a photodiode array detector, substances absorbing in the range 300 to 600 nm were identified in extracts from parasite material. These substances were not detected in extracts from cod tissue. Significant biochemical differences between cod muscle and parasite material have thus been demonstrated.

Historical DNA reveals the demographic history of Atlantic cod (Gadus morhua) in medieval and early modern Iceland

PubMed Central

Ólafsdóttir, Guðbjörg Ásta; Westfall, Kristen M.; Edvardsson, Ragnar; Pálsson, Snæbjörn

2014-01-01

Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500–1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400–1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change. PMID:24403343

Historical DNA reveals the demographic history of Atlantic cod (Gadus morhua) in medieval and early modern Iceland.

PubMed

Ólafsdóttir, Guðbjörg Ásta; Westfall, Kristen M; Edvardsson, Ragnar; Pálsson, Snæbjörn

2014-02-22

Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500-1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400-1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change.

Evidence for spawning aggregations of the endangered Atlantic goliath grouper Epinephelus itajara in southern Brazil.

PubMed

Bueno, L S; Bertoncini, A A; Koenig, C C; Coleman, F C; Freitas, M O; Leite, J R; De Souza, T F; Hostim-Silva, M

2016-07-01

In this study, seasonal numerical abundance of the critically endangered Atlantic goliath grouper Epinephelus itajara was estimated by conducting scuba dive surveys and calculating sightings-per-unit-effort (SPUE) at three sites in southern Brazil. Seasonal differences in size and reproductive condition of captured or confiscated specimens were compared. The SPUE differed significantly with season, increasing in late spring and peaking during the austral summer months. A significant effect was observed in the number of fish relative to the lunar cycle. All females sampled during the summer were spawning capable, while all those sampled during other seasons were either regressing or regenerating. What these data strongly infer is that the E. itajara spawning aggregation sites have been located in the southern state of Paraná and the northern state of Santa Catarina and summer is the most likely spawning season. Size frequency distributions, abundance and reproductive state were estimated and correlated with environmental variables. © 2016 The Fisheries Society of the British Isles.

Food web dynamics affect Northeast Arctic cod recruitment.

PubMed

Hjermann, Dag Ø; Bogstad, Bjarte; Eikeset, Anne Maria; Ottersen, Geir; Gjøsaeter, Harald; Stenseth, Nils Chr

2007-03-07

Proper management of ecosystems requires an understanding of both the species interactions as well as the effect of climate variation. However, a common problem is that the available time-series are of different lengths. Here, we present a general approach for studying the dynamic structure of such interactions. Specifically, we analyse the recruitment of the world's largest cod stock, the Northeast Arctic cod. Studies based on data starting in the 1970-1980s indicate that this stock is affected by temperature through a variety of pathways. However, the value of such studies is somewhat limited by the fact that they are based on a quite specific ecological and climatic situation. Recently, this stock has consisted of fairly young fish and the spawning stock has consisted of relatively few age groups. In this study, we develop a model for the effect of capelin (the cod's main prey) and herring on cod recruitment since 1973. Based on this model, we analyse data on cod, herring and temperature going back to 1921 and find that food-web effects explain a significant part of the cod recruitment variation back to around 1950.

Extracellular glucose can fuel metabolism in red blood cells from high glycemic Atlantic cod (Gadus morhua) but not low glycemic short-horned sculpin (Myoxocephalus scorpius).

PubMed

Driedzic, William R; Clow, Kathy A; Short, Connie E

2014-11-01

Energy metabolism was assessed in red blood cells (RBCs) from Atlantic cod and short-horned sculpin, two species that have markedly different levels of blood glucose. The objective was to determine whether the level of extracellular glucose has an impact on rates of glucose metabolism. The blood glucose level was 2.5 mmol l(-1) in Atlantic cod and 0.2 mmol l(-1) in short-horned sculpin, respectively. Oxygen consumption, lactate production and glucose utilization were measured in whole blood and related to grams of RBCs. Glucose utilization was assessed by measuring both glucose disappearance and the production of (3)H2O from [2-(3)H]-glucose. RBCs from both species have an aerobic-based metabolism. In Atlantic cod, extracellular glucose is sufficient to provide the sum of glucosyl equivalents to support both oxidative metabolism and lactate production. In contrast, extracellular glucose can account for only 10% of the metabolic rate in short-horned sculpin RBCs. In both species, about 70% of glucose enters the RBCs via facilitated transport. The difference in rates of extracellular glucose utilization is related to the extremely low levels of blood glucose in short-horned sculpin. In this species energy metabolism by RBCs must be supported by alternative fuels. © 2014. Published by The Company of Biologists Ltd.

Experimental parameterisation of principal physics in buoyancy variations of marine teleost eggs.

PubMed

Jung, Kyung-Mi; Folkvord, Arild; Kjesbu, Olav Sigurd; Sundby, Svein

2014-01-01

It is generally accepted that the high buoyancy of pelagic marine eggs is due to substantial influx of water across the cell membrane just before ovulation. Here we further develop the theoretical basis by applying laboratory observations of the various components of the fertilized egg in first-principle equations for egg specific gravity (ρ(egg)) followed by statistical validation. We selected Atlantic cod as a model animal due to the affluent amount of literature on this species, but also undertook additional dedicated experimental works. We found that specific gravity of yolk plus embryo is central in influencing ρ(egg) and thereby the buoyancy. However, our established framework documents the effect on ρ(egg) of the initial deposition of the heavy chorion material in the gonad prior to spawning. Thereafter, we describe the temporal changes in ρ(egg) during incubation: Generally, the eggs showed a slight rise in ρ(egg) from fertilization to mid-gastrulation followed by a gradual decrease until full development of main embryonic organs just before hatching. Ontogenetic changes in ρ(egg) were significantly associated with volume and mass changes of yolk plus embryo. The initial ρ(egg) at fertilization appeared significantly influenced by the chorion volume fraction which is determined by the combination of the final chorion volume of the oocyte and of the degree of swelling (hydrolyzation) prior to spawning. The outlined principles and algorithms are universal in nature and should therefore be applicable to fish eggs in general.

Experimental Parameterisation of Principal Physics in Buoyancy Variations of Marine Teleost Eggs

PubMed Central

Jung, Kyung-Mi; Folkvord, Arild; Kjesbu, Olav Sigurd; Sundby, Svein

2014-01-01

It is generally accepted that the high buoyancy of pelagic marine eggs is due to substantial influx of water across the cell membrane just before ovulation. Here we further develop the theoretical basis by applying laboratory observations of the various components of the fertilized egg in first-principle equations for egg specific gravity (ρegg) followed by statistical validation. We selected Atlantic cod as a model animal due to the affluent amount of literature on this species, but also undertook additional dedicated experimental works. We found that specific gravity of yolk plus embryo is central in influencing ρegg and thereby the buoyancy. However, our established framework documents the effect on ρegg of the initial deposition of the heavy chorion material in the gonad prior to spawning. Thereafter, we describe the temporal changes in ρegg during incubation: Generally, the eggs showed a slight rise in ρegg from fertilization to mid-gastrulation followed by a gradual decrease until full development of main embryonic organs just before hatching. Ontogenetic changes in ρegg were significantly associated with volume and mass changes of yolk plus embryo. The initial ρegg at fertilization appeared significantly influenced by the chorion volume fraction which is determined by the combination of the final chorion volume of the oocyte and of the degree of swelling (hydrolyzation) prior to spawning. The outlined principles and algorithms are universal in nature and should therefore be applicable to fish eggs in general. PMID:25122447

Life on the edge: O2 binding in Atlantic cod red blood cells near their southern distribution limit is not sensitive to temperature or haemoglobin genotype

PubMed Central

Barlow, Samantha L.; Metcalfe, Julian; Righton, David A.

2017-01-01

ABSTRACT Atlantic cod are a commercially important species believed to be threatened by warming seas near their southern, equatorward upper thermal edge of distribution. Limitations to circulatory O2 transport, in particular cardiac output, and the geographic distribution of functionally different haemoglobin (Hb) genotypes have separately been suggested to play a role in setting thermal tolerance in this species. The present study assessed the thermal sensitivity of O2 binding in Atlantic cod red blood cells with different Hb genotypes near their upper thermal distribution limit and modelled its consequences for the arterio-venous O2 saturation difference, Sa–vO2, another major determinant of circulatory O2 supply rate. The results showed statistically indistinguishable red blood cell O2 binding between the three HbI genotypes in wild-caught Atlantic cod from the Irish Sea (53° N). Red blood cells had an unusually low O2 affinity, with reduced or even reversed thermal sensitivity between pH 7.4 and 7.9, and 5.0 and 20.0°C. This was paired with strongly pH-dependent affinity and cooperativity of red blood cell O2 binding (Bohr and Root effects). Modelling of Sa–vO2 at physiological pH, temperature and O2 partial pressures revealed a substantial capacity for increases in Sa–vO2 to meet rising tissue O2 demands at 5.0 and 12.5°C, but not at 20°C. Furthermore, there was no evidence for an increase of maximal Sa–vO2 with temperature. It is suggested that Atlantic cod at such high temperatures may solely depend on increases in cardiac output and blood O2 capacity, or thermal acclimatisation of metabolic rate, for matching circulatory O2 supply to tissue demand. PMID:28148818

Life on the edge: O2 binding in Atlantic cod red blood cells near their southern distribution limit is not sensitive to temperature or haemoglobin genotype.

PubMed

Barlow, Samantha L; Metcalfe, Julian; Righton, David A; Berenbrink, Michael

2017-02-01

Atlantic cod are a commercially important species believed to be threatened by warming seas near their southern, equatorward upper thermal edge of distribution. Limitations to circulatory O 2 transport, in particular cardiac output, and the geographic distribution of functionally different haemoglobin (Hb) genotypes have separately been suggested to play a role in setting thermal tolerance in this species. The present study assessed the thermal sensitivity of O 2 binding in Atlantic cod red blood cells with different Hb genotypes near their upper thermal distribution limit and modelled its consequences for the arterio-venous O 2 saturation difference, Sa-v O 2 , another major determinant of circulatory O 2 supply rate. The results showed statistically indistinguishable red blood cell O 2 binding between the three HbI genotypes in wild-caught Atlantic cod from the Irish Sea (53° N). Red blood cells had an unusually low O 2 affinity, with reduced or even reversed thermal sensitivity between pH 7.4 and 7.9, and 5.0 and 20.0°C. This was paired with strongly pH-dependent affinity and cooperativity of red blood cell O 2 binding (Bohr and Root effects). Modelling of Sa-v O 2  at physiological pH, temperature and O 2 partial pressures revealed a substantial capacity for increases in Sa-v O 2  to meet rising tissue O 2 demands at 5.0 and 12.5°C, but not at 20°C. Furthermore, there was no evidence for an increase of maximal Sa-v O 2  with temperature. It is suggested that Atlantic cod at such high temperatures may solely depend on increases in cardiac output and blood O 2 capacity, or thermal acclimatisation of metabolic rate, for matching circulatory O 2 supply to tissue demand. © 2017. Published by The Company of Biologists Ltd.

Effects of Loma morhua (Microsporidia) infection on the cardiorespiratory performance of Atlantic cod Gadus morhua (L).

PubMed

Powell, M D; Gamperl, A K

2016-02-01

The microsporidian Loma morhua infects Atlantic cod (Gadus morhua) in the wild and in culture and results in the formation of xenomas within the gill filaments, heart and spleen. Given the importance of the two former organs to metabolic capacity and thermal tolerance, the cardiorespiratory performance of cod with a naturally acquired infection of Loma was measured during an acute temperature increase (2 °C h(-1)) from 10 °C to the fish's critical thermal maximum (CT(Max)). In addition, oxygen consumption and swimming performance were measured during two successive critical swimming speed (U(crit)) tests at 10 °C. While Loma infection had a negative impact on cod cardiac function at warm temperatures, and on metabolic capacity in both the CT(Max) and U(crit) tests (i.e. a reduction of 30-40%), it appears that the Atlantic cod can largely compensate for these Loma-induced cardiorespiratory limitations. For example, (i) CT(Max) (21.0 ± 0.3 °C) and U(crit) (~1.75 BL s(-1)) were very comparable to those reported in previous studies using uninfected fish from the same founder population; and (ii) our data suggest that tissue oxygen extraction, and potentially the capacity for anaerobic metabolism, is enhanced in fish infected with this microsporidian. © 2015 The Authors Journal of Fish Diseases Published by John Wiley & Sons Ltd.

Ontogenetic behavior and migration of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus, and shortnose sturgeon, A. brevirostrum, with notes on social behavior

USGS Publications Warehouse

Kynard, B.; Horgan, M.

2002-01-01

Ontogenetic behavior of Hudson River Atlantic sturgeon and Connecticut River shortnose sturgeon early life intervals were similar during laboratory observations. After hatching, free embryos were photonegative and sought cover. When embryos developed into larvae, fish left cover, were photopositive, and initiated downstream migration. Free embryos may remain at the spawning site instead of migrating downstream because the risk of predation at spawning sites is low. The two species are sympatric, but not closely related, so the similarities in innate behaviors suggest common adaptations, not phylogenetlc relationship. Atlantic sturgeon migrated downstream for 12 days (peak, first 6 days), shortnose sturgeon migrated for 3 days, and year-0 juveniles of both species did not resume downstream migration. Short or long migrations of larvae may reflect different styles related to the total migratory distance from spawning sites to juvenile rearing areas. Atlantic sturgeon need to move a short distance to reach rearing areas and they had a long 1-step migration of 6-12 days. In contrast, shortnose sturgeon need to move a long distance to reach all rearing areas. This may be accomplished by a 2-step migration, of which the brief migration of larvae is only the first step. Early migrant Atlantic sturgeon were nocturnal, while late migrants were diurnal, and shortnose sturgeon were diurnal. These diel differences may also be adaptations for long (Atlantic sturgeon) or short (shortnose sturgeon) migrations. Cultured shortnose sturgeon, and possibly Atlantic sturgeon, have a dominance hierarchy with large fish dominant when competing for limited foraging space. Social behavior may be more important in the life history of wild sturgeons than is generally recognized.

A probabilistic approach to quantifying hydrologic thresholds regulating migration of adult Atlantic salmon into spawning streams

NASA Astrophysics Data System (ADS)

Lazzaro, G.; Soulsby, C.; Tetzlaff, D.; Botter, G.

2017-03-01

Atlantic salmon is an economically and ecologically important fish species, whose survival is dependent on successful spawning in headwater rivers. Streamflow dynamics often have a strong control on spawning because fish require sufficiently high discharges to move upriver and enter spawning streams. However, these streamflow effects are modulated by biological factors such as the number and the timing of returning fish in relation to the annual spawning window in the fall/winter. In this paper, we develop and apply a novel probabilistic approach to quantify these interactions using a parsimonious outflux-influx model linking the number of female salmon emigrating (i.e., outflux) and returning (i.e., influx) to a spawning stream in Scotland. The model explicitly accounts for the interannual variability of the hydrologic regime and the hydrological connectivity of spawning streams to main rivers. Model results are evaluated against a detailed long-term (40 years) hydroecological data set that includes annual fluxes of salmon, allowing us to explicitly assess the role of discharge variability. The satisfactory model results show quantitatively that hydrologic variability contributes to the observed dynamics of salmon returns, with a good correlation between the positive (negative) peaks in the immigration data set and the exceedance (nonexceedance) probability of a threshold flow (0.3 m3/s). Importantly, model performance deteriorates when the interannual variability of flow regime is disregarded. The analysis suggests that flow thresholds and hydrological connectivity for spawning return represent a quantifiable and predictable feature of salmon rivers, which may be helpful in decision making where flow regimes are altered by water abstractions.

Effects of long-term temperature acclimation on thyroid hormone deiodinase function, plasma thyroid hormone levels, growth, and reproductive status of male Atlantic cod, Gadus morhua.

PubMed

Cyr, D G; Idler, D R; Audet, C; McLeese, J M; Eales, J G

1998-01-01

The recent collapse of the Northwestern Atlantic cod fisheries has coincided with a cooling of water temperatures. During this time the condition factor of cod has been poor. The objective of the present study was to determine the effects of long-term temperature acclimation on growth reproduction and thyroid function in laboratory held Atlantic cod (Gadus morhua). One of the key parameters used to assess thyroid function is the peripheral metabolism of L-thyroxine (T4) by microsomal deiodinase enzymes. Deiodinase function has not been described for gadid fish. T4 outer-ring deiodinating activity (apparent K(m) 1-2 nM) was confined primarily to liver. Its properties resembled those for hepatic T4ORD activity of other teleosts and the mammalian type II deiodinase. The T4ORD activity of cod liver exceeded that of salmonids and could explain the high plasma T3 levels (10-18 ng/ml), which were 2-5 times greater than T4 levels. T4 and T3 inner-ring deiodination was confined mainly to brain. In order to determine the effects of long-term temperature acclimation on cod, somatic growth, reproduction, and thyroidal status were assessed monthly in 400-900-g satiation-fed male Atlantic cod captured in June from the St. Lawrence Estuary and then acclimated from August to the following June under a natural photoperiod at 2-4 degrees C (LT) or 6-10 degrees C (HT). Reproductive status was determined from the gonadosomatic index (GSI), plasma testosterone (T) and 11-ketotestosterone (11-KT) levels, and the appearance of milt; thyroidal status was determined from plasma T4 and 3,5,3'-triiodo-L-thyronine (T3) levels and hepatic T4ORD activity to produce biologically active T3. Testis maturation (high levels of 1 and 11-KT, and milt release) occurred in April and May and was uninfluenced by acclimation temperature. LT cod grew more slowly than HT cod. Differences in body weight were particularly evident from December to February. In conclusion, (i) cod possess outer- and inner-ring deiodinase activities, predominating respectively in liver and brain, and with properties resembling those of other teleosts, (ii) T4ORD activity of liver is unusually high and may account for the high plasma T3 levels in this species, (iii) T4ORD activity tends to increase during periods of increased somatic growth, and (iv) chronic acclimation of male cod to 2-4 degrees C, as opposed to 6-10 degrees C, decreases somatic growth but does alter circulating levels of thyroid hormones and androgens and it does not change the time of sexual maturation.

Patterns of larval source distribution and mixing in early life stages of Pacific cod (Gadus macrocephalus) in the southeastern Bering Sea

NASA Astrophysics Data System (ADS)

Miller, Jessica A.; DiMaria, Ruth A.; Hurst, Thomas P.

2016-12-01

Effective and sustainable management depends on knowledge of spawning locations and their relative contributions to marine fish populations. Pacific cod (Gadus macrocephalus) in the southeastern Bering Sea aggregate at discrete spawning locations but there is little information on patterns of larval dispersal and the relative contribution of specific spawning areas to nursery habitats. Age-0 Pacific cod from two cohorts (2006 and 2008) were examined to address the following questions: (1) does size, age, and otolith chemistry vary among known capture locations; (2) can variation in elemental composition of the otolith cores (early larval signatures) be used to infer the number of chemically distinct sources contributing to juvenile recruits in the Bering Sea; and (3) to what extent are juvenile collection locations represented by groups of fish with similar chemical histories throughout their early life history? Hierarchical cluster (HCA) and discriminant function analyses (DFA) were used to examine variation in otolith chemistry at discrete periods throughout the early life history. HCA identified five chemically distinct groups of larvae in the 2006 cohort and three groups in 2008; however, three sources accounted for 80-100% of the juveniles in each year. DFA of early larval signatures indicated that there were non-random spatial distributions of early larvae in both years, which may reflect interannual variation in regional oceanography. There was also a detectable and substantial level of coherence in chemical signatures within groups of fish throughout the early life history. The variation in elemental signatures throughout the early life history (hatch to capture) indicates that otolith chemical analysis could be an effective tool to further clarify larval sources and dispersal, identify juvenile nursery habitats, and estimate the contributions of juvenile nursery habitats to the adult population within the southeastern Bering Sea.

Harvest Pressure on Coastal Atlantic Cod (Gadus morhua) from Recreational Fishing Relative to Commercial Fishing Assessed from Tag-Recovery Data

PubMed Central

Kleiven, Alf Ring; Fernandez-Chacon, Albert; Nordahl, Jan-Harald; Moland, Even; Espeland, Sigurd Heiberg; Knutsen, Halvor; Olsen, Esben Moland

2016-01-01

Marine recreational fishing is a popular outdoor activity. However, knowledge about the magnitude of recreational catches relative to commercial catches in coastal fisheries is generally sparse. Coastal Atlantic cod (Gadus morhua) is a target species for recreational fishers in the North Atlantic. In Norway, recreational fishers are allowed to use a variety of traps and nets as well as long-line and rod and line when fishing for cod. From 2005 to 2013, 9729 cod (mean size: 40 cm, range: 15–93 cm) were tagged and released in coastal Skagerrak, southeast Norway. Both high-reward (NOK 500) and low-reward tags (NOK 50) were used in this study. Because some harvested fish (even those posting high-reward tags) may go unreported by fishers, reporting rates were estimated from mark-recovery models that incorporate detection parameters in their structure, in addition to survival and mortality estimates. During 2005 to 2013, a total of 1707 tagged cod were recovered and reported by fishers. We estimate the overall annual survival to be 33% (SE 1.5). Recreational rod and line fishing were responsible for 33.7% (SE 2.4) of total mortality, followed by commercial fisheries (15.1% SE 0.8) and recreational fixed gear (6.8% SE 0.4). Natural mortality was 44.4% (SE 2.5) of total mortality. Our findings suggest that recreational fishing—rod and line fishing in particular—is responsible for a substantial part of fishing mortality exerted on coastal cod in southern Norway. PMID:26959371

Harvest Pressure on Coastal Atlantic Cod (Gadus morhua) from Recreational Fishing Relative to Commercial Fishing Assessed from Tag-Recovery Data.

PubMed

Kleiven, Alf Ring; Fernandez-Chacon, Albert; Nordahl, Jan-Harald; Moland, Even; Espeland, Sigurd Heiberg; Knutsen, Halvor; Olsen, Esben Moland

2016-01-01

Marine recreational fishing is a popular outdoor activity. However, knowledge about the magnitude of recreational catches relative to commercial catches in coastal fisheries is generally sparse. Coastal Atlantic cod (Gadus morhua) is a target species for recreational fishers in the North Atlantic. In Norway, recreational fishers are allowed to use a variety of traps and nets as well as long-line and rod and line when fishing for cod. From 2005 to 2013, 9729 cod (mean size: 40 cm, range: 15-93 cm) were tagged and released in coastal Skagerrak, southeast Norway. Both high-reward (NOK 500) and low-reward tags (NOK 50) were used in this study. Because some harvested fish (even those posting high-reward tags) may go unreported by fishers, reporting rates were estimated from mark-recovery models that incorporate detection parameters in their structure, in addition to survival and mortality estimates. During 2005 to 2013, a total of 1707 tagged cod were recovered and reported by fishers. We estimate the overall annual survival to be 33% (SE 1.5). Recreational rod and line fishing were responsible for 33.7% (SE 2.4) of total mortality, followed by commercial fisheries (15.1% SE 0.8) and recreational fixed gear (6.8% SE 0.4). Natural mortality was 44.4% (SE 2.5) of total mortality. Our findings suggest that recreational fishing-rod and line fishing in particular-is responsible for a substantial part of fishing mortality exerted on coastal cod in southern Norway.

Behavioral responses of Atlantic cod to sea temperature changes.

PubMed

Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

2015-05-01

Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30-80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species.

Behavioral responses of Atlantic cod to sea temperature changes

PubMed Central

Freitas, Carla; Olsen, Esben Moland; Moland, Even; Ciannelli, Lorenzo; Knutsen, Halvor

2015-01-01

Understanding responses of marine species to temperature variability is essential to predict impacts of future climate change in the oceans. Most ectotherms are expected to adjust their behavior to avoid extreme temperatures and minimize acute changes in body temperature. However, measuring such behavioral plasticity in the wild is challenging. Combining 4 years of telemetry-derived behavioral data on juvenile and adult (30–80 cm) Atlantic cod (Gadus morhua), and in situ ocean temperature measurements, we found a significant effect of sea temperature on cod depth use and activity level in coastal Skagerrak. During summer, cod were found in deeper waters when sea surface temperature increased. Further, this effect of temperature was stronger on larger cod. Diel vertical migration, which consists in a nighttime rise to shallow feeding habitats, was stronger among smaller cod. As surface temperature increased beyond ∼15°C, their vertical migration was limited to deeper waters. In addition to larger diel vertical migrations, smaller cod were more active and travelled larger distances compared to larger specimens. Cold temperatures during winter tended, however, to reduce the magnitude of diel vertical migrations, as well as the activity level and distance moved by those smaller individuals. Our findings suggest that future and ongoing rises in sea surface temperature may increasingly deprive cod in this region from shallow feeding areas during summer, which may be detrimental for local populations of the species. PMID:26045957

Injection-salting and cold-smoking of farmed atlantic cod (Gadus morhua L.) and Atlantic salmon (Salmo salar L.) at different stages of Rigor Mortis: effect on physical properties.

PubMed

Akse, L; Birkeland, S; Tobiassen, T; Joensen, S; Larsen, R

2008-10-01

Processing of fish is generally conducted postrigor, but prerigor processing is associated with some potential advantages. The aim of this study was to study how 5 processing regimes of cold-smoked cod and salmon conducted at different stages of rigor influenced yield, fillet shrinkage, and gaping. Farmed cod and salmon was filleted, salted by brine injection of 25% NaCl, and smoked for 2 h at different stages of rigor. Filleting and salting prerigor resulted in increased fillet shrinkage and less increase in weight during brine injection, which in turn was correlated to the salt content of the fillet. These effects were more pronounced in cod fillets when compared to salmon. Early processing reduced fillet gaping and fillets were evaluated as having a firmer texture. In a follow-up trial with cod, shrinkage and weight gain during injection was studied as an effect of processing time postmortem. No changes in weight gain were observed for fillets salted the first 24 h postmortem; however, by delaying the processing 12 h postmortem, the high and rapid shrinking of cod fillets during brine injection was halved.

Will you swim into my parlour? In situ observations of Atlantic cod (Gadus morhua) interactions with baited pots, with implications for gear design

PubMed Central

Walsh, Philip; Favaro, Brett

2017-01-01

Pots (also known as traps) are baited fishing gears widely used in commercial fisheries, and are being considered as a tool for harvesting Atlantic cod (Gadus morhua) in Newfoundland and Labrador, Canada. Pots produce lower environmental impacts than many other fishing gears, but they will only be a viable fishing strategy if they are efficient and selective at catching their target species. To study the behaviour of cod in and around pots, and how those behaviours affect pot efficiency, we used long-duration underwater video cameras to assess two models of cod pot deployed in the nearshore waters of Fogo Island, NL. We examined the number of cod that approached the pot, the number and proportion that successfully completed entries into the pot openings, and the number that exited, and related these factors to the direction of water movement. We observed very few entry attempts relative to the number of approaches by cod, and only 22% of all entry attempts were successful. We observed that 50% of approaches, 70% of entry attempts, and 73% of successful entrances occurred against the current, and 25% of cod were able to exit the pot following capture. Based on our observations, we suggest that future cod pots should have a greater number of entrances, or a mechanism to ensure that entrances rotate in line with the current, in order to maximize their catch efficiency for cod. PMID:28194312

Will you swim into my parlour? In situ observations of Atlantic cod (Gadus morhua) interactions with baited pots, with implications for gear design.

PubMed

Meintzer, Phillip; Walsh, Philip; Favaro, Brett

2017-01-01

Pots (also known as traps) are baited fishing gears widely used in commercial fisheries, and are being considered as a tool for harvesting Atlantic cod ( Gadus morhua ) in Newfoundland and Labrador, Canada. Pots produce lower environmental impacts than many other fishing gears, but they will only be a viable fishing strategy if they are efficient and selective at catching their target species. To study the behaviour of cod in and around pots, and how those behaviours affect pot efficiency, we used long-duration underwater video cameras to assess two models of cod pot deployed in the nearshore waters of Fogo Island, NL. We examined the number of cod that approached the pot, the number and proportion that successfully completed entries into the pot openings, and the number that exited, and related these factors to the direction of water movement. We observed very few entry attempts relative to the number of approaches by cod, and only 22% of all entry attempts were successful. We observed that 50% of approaches, 70% of entry attempts, and 73% of successful entrances occurred against the current, and 25% of cod were able to exit the pot following capture. Based on our observations, we suggest that future cod pots should have a greater number of entrances, or a mechanism to ensure that entrances rotate in line with the current, in order to maximize their catch efficiency for cod.

Variation in embryonic mortality and maternal transcript expression among Atlantic cod (Gadus morhua) broodstock: a functional genomics study.

PubMed

Rise, Matthew L; Nash, Gordon W; Hall, Jennifer R; Booman, Marije; Hori, Tiago S; Trippel, Edward A; Gamperl, A Kurt

2014-12-01

Early life stage mortality is an important issue for Atlantic cod aquaculture, yet the impact of the cod maternal (egg) transcriptome on egg quality and mortality during embryonic development is poorly understood. In the present work, we studied embryonic mortality and maternal transcript expression using eggs from 15 females. Total mortality at 7days post-fertilization (7 dpf, segmentation stage) was used as an indice of egg quality. A 20,000 probe (20K) microarray experiment compared the 7hours post-fertilization (7 hpf, ~2-cell stage) egg transcriptome of the two lowest quality females (>90% mortality at 7 dpf) to that of the highest quality female (~16% mortality at 7 dpf). Forty-three microarray probes were consistently differentially expressed in both low versus high quality egg comparisons (25 higher expressed in low quality eggs, and 18 higher expressed in high quality eggs). The microarray experiment also identified many immune-relevant genes [e.g. interferon (IFN) pathway genes ifngr1 and ifrd1)] that were highly expressed in eggs of all 3 females regardless of quality. Twelve of the 43 candidate egg quality-associated genes, and ifngr1, ifrd1 and irf7, were included in a qPCR study with 7 hpf eggs from all 15 females. Then, the genes that were confirmed by qPCR to be greater than 2-fold differentially expressed between 7 hpf eggs from the lowest and highest quality females (dcbld1, ddc, and acy3 more highly expressed in the 2 lowest quality females; kpna7 and hacd1 more highly expressed in the highest quality female), and the 3 IFN pathway genes, were included in a second qPCR study with unfertilized eggs. While some maternal transcripts included in these qPCR studies were associated with extremes in egg quality, there was little correlation between egg quality and gene expression when all females were considered. Both dcbld1 and ddc showed greater than 100-fold differences in transcript expression between females and were potentially influenced by family. The Atlantic cod ddc (dopa decarboxylase) complete cDNA was characterized, and has a 1461bp open reading frame encoding a 486 amino acid protein that contains all eight residues of the conserved pyridoxal 5'-phosphate binding site including the catalytic lysine. This study provides valuable new information and resources related to the Atlantic cod egg transcriptome. Some of these microarray-identified, qPCR-confirmed, Atlantic cod egg transcripts (e.g. ddc, kpna7) play important roles during embryonic development of other vertebrate species, and may have similar functions in Atlantic cod. Copyright © 2014. Published by Elsevier B.V.

Study of the plasma proteome of Atlantic cod (Gadus morhua): Effect of exposure to two PAHs and their corresponding diols.

PubMed

Skogland Enerstvedt, Karianne; Sydnes, Magne O; Pampanin, Daniela M

2017-09-01

Occurrence of polycyclic aromatic hydrocarbon (PAH) contamination in the marine environment represents a risk to marine life and humans. In this study, plasma samples from Atlantic cod (Gadus morhua) were analysed by shotgun mass spectrometry to investigate the plasma proteome in response to exposure to single PAHs (naphthalene or chrysene) and their corresponding metabolites (dihydrodiols). In total, 369 proteins were identified and ranked according to their relative abundance. The levels of 12 proteins were found significantly altered in PAH exposed fish and are proposed as new biomarker candidates. Eleven proteins were upregulated, primarily immunoglobulin components, and one protein was downregulated (antifreeze protein type IV.) The uniformity of the upregulated proteins suggests a triggered immune response in the exposed fish. Overall, the results provide valuable knowledge for future studies of the Atlantic cod plasma proteome and generate grounds for establishing new plasma protein biomarkers for environmental monitoring of PAH related exposure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Slow Adaptation in the Face of Rapid Warming Leads to the Collapse of Atlantic Cod in the Gulf of Maine

NASA Astrophysics Data System (ADS)

Pershing, A. J.; Alexander, M. A.; Hernandez, C.; Kerr, L. A.; Le Bris, A.; Mills, K.; Nye, J. A.; Record, N.; Scannell, H. A.; Scott, J. D.; Sherwood, G. D.; Thomas, A. C.

2016-02-01

Climate change is altering conditions in all marine ecosystems, but the pace of change is not uniform. Rapid changes in environmental conditions pose a challenge for resource management, especially when available tools or policies assume the environment is stationary. Between 2004 and 2013, the Gulf of Maine and northwest Atlantic Shelf warmed at a rate that few large marine ecosystems have ever experienced. This warming was associated with a northward shift in the Gulf Stream and with Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation. The unprecedented warming led to reduced recruitment and enhanced mortality of Atlantic cod. Fisheries management has built-in feedbacks designed to reduce quotas as populations decline, but the management process could not keep pace with the rapid temperature-related changes in the Gulf of Maine cod stock. Future recovery of this fishery now depends on both sound management and favorable temperatures. The experience in the Gulf of Maine highlights the need to incorporate environmental factors into resource management and to build resiliency in coupled social-ecological systems. It also highlights a need for scientific and policy guidance for managing species threatened by future warming.

Assessing impacts of simulated oil spills on the Northeast Arctic cod fishery.

PubMed

Carroll, JoLynn; Vikebø, Frode; Howell, Daniel; Broch, Ole Jacob; Nepstad, Raymond; Augustine, Starrlight; Skeie, Geir Morten; Bast, Radovan; Juselius, Jonas

2018-01-01

We simulate oil spills of 1500 and 4500m 3 /day lasting 14, 45, and 90days in the spawning grounds of the commercial fish species, Northeast Arctic cod. Modeling the life history of individual fish eggs and larvae, we predict deviations from the historical pattern of recruitment to the adult population due to toxic oil exposures. Reductions in survival for pelagic stages of cod were 0-10%, up to a maximum of 43%. These reductions resulted in a decrease in adult cod biomass of <3% for most scenarios, up to a maximum of 12%. In all simulations, the adult population remained at full reproductive potential with a sufficient number of juveniles surviving to replenish the population. The diverse age distribution helps protect the adult cod population from reductions in a single year's recruitment after a major oil spill. These results provide insights to assist in managing oil spill impacts on fisheries. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Substitution of fish oil with camelina oil and inclusion of camelina meal in diets fed to Atlantic cod (Gadus morhua) and their effects on growth, tissue lipid classes, and fatty acids.

PubMed

Hixson, S M; Parrish, C C

2014-03-01

Developing a commercially relevant Atlantic cod aquaculture industry will require improvements in feed sustainability. Camelina oil and meal are potential replacements of fish oil and fish meal in aquaculture feeds. Camelina oil is high in 18:3ω3 (30%), with an ω3/ω6 ratio > 1. Camelina meal has a considerable crude protein level (38%), which includes significant amounts of methionine and phenylalanine. Four diets were tested; each diet was fed to triplicate tanks (3 tanks per diet) of Atlantic cod (14.4 g/fish; 70 fish per tank) for 13 wk. The diets included a fish oil/fish meal control (FO) and three diets which replaced 100% of fish oil with camelina oil: one diet contained fish meal (100CO), another solvent extracted fish meal (100COSEFM), and another had fish meal partially reduced by 15% inclusion of camelina meal (100CO15CM). Growth was measured (length and weight) and tissue samples were collected for lipid analysis (muscle, liver, brain, gut, spleen, skin, and carcass) at wk 0 (before feeding the experimental diet) and at wk 13. Cod fed camelina oil had a lower (P < 0.001) final weight than cod fed the FO diet (50.8 ± 10.3 g/fish). Cod fed 100CO15CM had a lower (P < 0.001) final weight (35.0 ± 8.0 g) than those fed 100CO (43.6 ± 8.9 g) and 100COSEFM (46.7 ± 10.7 g). Cod tissues in the 100COSEFM treatment were most impacted by dietary fatty acid profile. Multivariate statistics revealed that FO and 100COSEFM tissue fatty acid profiles were 21 to 31% different, depending on tissue type. The full replacement of fish oil with camelina oil, plus solvent extracted fish meal had an overarching effect on the entire fatty acid profile of the whole animal. Fatty acid mass balance calculations indicated that cod fed 100COSEFM elongated 13% of 18:3ω3 to 20:3ω3 and oxidized the remaining 87%, whereas cod fed fish oil showed a much lower (P < 0.001) elongation of 18:3ω3 of 1.6%. These results suggest that excess 18:3ω3 from camelina oil caused some fatty acid elongation, but little desaturation. Energy budget estimates indicated that cod fed 100COSEFM deposited the most energy throughout the trial (60 kJ/fish; P = 0.019), mostly in the liver (90%). Excess camelina lipids were not necessarily utilized for energy, which likely impacted growth. Feeding 100% camelina oil to Atlantic cod impacted growth and lipid and fatty acid composition; however, additional removal of fish oil from fish meal caused the greatest change in cod lipid composition and utilization.

Spillover of the Atlantic bluefin tuna offspring from cages in the Adriatic Sea: A multidisciplinary approach and assessment.

PubMed

Džoić, Tomislav; Beg Paklar, Gordana; Grbec, Branka; Ivatek-Šahdan, Stjepan; Zorica, Barbara; Šegvić-Bubić, Tanja; Čikeš Keč, Vanja; Lepen Pleić, Ivana; Mladineo, Ivona; Grubišić, Leon; Verley, Philippe

2017-01-01

During routine monitoring of commercial purse seine catches in 2011, 87 fingerling specimens of scombrids were collected in the southern Adriatic Sea. Sequencing of the mitochondrial DNA control region locus inferred that specimens belonged to the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) (N = 29), bullet tuna, Auxis rochei (Risso, 1810) (N = 30) and little tunny, Euthynnus alletteratus, Rafinesque, 1810 (N = 28). According to previously published growth parameters, the age of the collected specimens was estimated at approximately 30-40 days, suggesting they might have been spawned in the Adriatic Sea, contrary to the current knowledge. A coupled modelling system with hydrodynamic (ROMS) and individual based model (IBM-Ichthyop) was set up to determine the location of the spawning event. Numerical simulations with the IBM model, both backward and forward in time, indicate commercial tuna cages in the middle Adriatic coastal area as possible spawning location. The two other non-commercial species likely opportunistically use the positive environmental (abiotic and biotic) conditions to spawn in the same area.

Spillover of the Atlantic bluefin tuna offspring from cages in the Adriatic Sea: A multidisciplinary approach and assessment

PubMed Central

2017-01-01

During routine monitoring of commercial purse seine catches in 2011, 87 fingerling specimens of scombrids were collected in the southern Adriatic Sea. Sequencing of the mitochondrial DNA control region locus inferred that specimens belonged to the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) (N = 29), bullet tuna, Auxis rochei (Risso, 1810) (N = 30) and little tunny, Euthynnus alletteratus, Rafinesque, 1810 (N = 28). According to previously published growth parameters, the age of the collected specimens was estimated at approximately 30–40 days, suggesting they might have been spawned in the Adriatic Sea, contrary to the current knowledge. A coupled modelling system with hydrodynamic (ROMS) and individual based model (IBM—Ichthyop) was set up to determine the location of the spawning event. Numerical simulations with the IBM model, both backward and forward in time, indicate commercial tuna cages in the middle Adriatic coastal area as possible spawning location. The two other non-commercial species likely opportunistically use the positive environmental (abiotic and biotic) conditions to spawn in the same area. PMID:29190825

A Novel Method for Predicting Anisakid Nematode Infection of Atlantic Cod Using Rough Set Theory.

PubMed

Wąsikowska, Barbara; Sobecka, Ewa; Bielat, Iwona; Legierko, Monika; Więcaszek, Beata

2018-03-01

Atlantic cod ( Gadus morhua L.) is one of the most important fish species in the fisheries industries of many countries; however, these fish are often infected with parasites. The detection of pathogenic larval nematodes is usually performed in fish processing facilities by visual examination using candling or by digesting muscles in artificial digestive juices, but these methods are both time and labor intensive. This article presents an innovative approach to the analysis of cod parasites from both the Atlantic and Baltic Sea areas through the application of rough set theory, one of the methods of artificial intelligence, for the prediction of food safety in a food production chain. The parasitological examinations were performed focusing on nematode larvae pathogenic to humans, e.g., Anisakis simplex, Contracaecum osculatum, and Pseudoterranova decipiens. The analysis allowed identification of protocols with which it is possible to make preliminary estimates of the quantity and quality of parasites found in cod catches before detailed analyses are performed. The results indicate that the method used can be an effective analytical tool for these types of data. To achieve this goal, a database is needed that contains the patterns intensity of parasite infections and the conditions of commercial fish species in different localities in their distributions.

Novel biodiversity baselines outpace models of fish distribution in Arctic waters

NASA Astrophysics Data System (ADS)

Christiansen, Jørgen S.; Bonsdorff, Erik; Byrkjedal, Ingvar; Fevolden, Svein-Erik; Karamushko, Oleg V.; Lynghammar, Arve; Mecklenburg, Catherine W.; Møller, Peter D. R.; Nielsen, Julius; Nordström, Marie C.; Præbel, Kim; Wienerroither, Rupert M.

2016-02-01

During a recent marine biological expedition to the Northeast Greenland shelf break (latitudes 74-77 °N), we made the first discovery of Atlantic cod ( Gadus morhua), beaked redfish ( Sebastes mentella) and capelin ( Mallotus villosus). Our novel observations shift the distribution range of Atlantic cod >1000 km further north in East Greenland waters. In light of climate change, we discuss physical forcing and putative connections between the faunas of the Northeast Greenland shelf and the Barents Sea. We emphasise the importance of using real data in spread scenarios for understudied Arctic seas.

Novel biodiversity baselines outpace models of fish distribution in Arctic waters.

PubMed

Christiansen, Jørgen S; Bonsdorff, Erik; Byrkjedal, Ingvar; Fevolden, Svein-Erik; Karamushko, Oleg V; Lynghammar, Arve; Mecklenburg, Catherine W; Møller, Peter D R; Nielsen, Julius; Nordström, Marie C; Præbel, Kim; Wienerroither, Rupert M

2016-02-01

During a recent marine biological expedition to the Northeast Greenland shelf break (latitudes 74-77 °N), we made the first discovery of Atlantic cod (Gadus morhua), beaked redfish (Sebastes mentella) and capelin (Mallotus villosus). Our novel observations shift the distribution range of Atlantic cod >1000 km further north in East Greenland waters. In light of climate change, we discuss physical forcing and putative connections between the faunas of the Northeast Greenland shelf and the Barents Sea. We emphasise the importance of using real data in spread scenarios for understudied Arctic seas.

Conspecific Sperm Precedence Is a Reproductive Barrier between Free-Spawning Marine Mussels in the Northwest Atlantic Mytilus Hybrid Zone

PubMed Central

Klibansky, Lara K. J.; McCartney, Michael A.

2014-01-01

Reproductive isolation at the gamete stage has become a focus of speciation research because of its potential to evolve rapidly between closely related species. Conspecific sperm precedence (CSP), a type of gametic isolation, has been demonstrated in a number of taxa, both marine and terrestrial, with the potential to play an important role in speciation. Free-spawning marine invertebrates are ideal subjects for the study of CSP because of a likely central role for gametic barriers in reproductive isolation. The western Atlantic Mytilus blue mussel hybrid zone, ranging from the Atlantic Canada to eastern Maine, exhibits characteristics conducive to the study of CSP. Previous studies have shown that gametic incompatibility is incomplete, variable in strength and the genotype distribution is bimodal—dominated by the parental species, with a low frequency of hybrids. We conducted gamete crossing experiments using M. trossulus and M. edulis individuals collected from natural populations during the spring spawning season in order to detect the presence or absence of CSP within this hybrid zone. We detected CSP, defined here as a reduction in heterospecific offspring from competitive fertilizations in vitro compared to that seen in non-competitive fertilizations, in five of the twelve crosses in which conspecific crosses were detectable. This is the first finding of CSP in a naturally hybridizing population of a free-spawning marine invertebrate. Our findings support earlier predictions that CSP can promote assortative fertilization in bimodal hybrid zones, further advancing their hypothesized progression towards full speciation. Despite strong CSP numerous heterospecific fertilizations remain, reinforcing the hypothesis that compatible females are a source of hybrid offspring in mixed natural spawns. PMID:25268856

Long Island Sound Thamesville Tidal-Flood Management Water Resources Study, Norwich, Connecticut.

DTIC Science & Technology

1981-02-01

waters are used for feeding and as spawning and nursery grounds for a variety of species, such as bluefish , Atlantic tomcod, striped bass, winter...fisheries for bluefish , ’ Atlantic tomcod, striped bass, winter flounder, American eel and alewife. r The Thames supports a heavily utilized sport fishery...for winter flounder, striped bass, white perch, American smelt, bluefish and Atlantic tomcod. Mummichog and Atlantic menhaden are the most common

Evaluation and refinement of Guadalupe Bass conservation strategies to support adaptive management

USGS Publications Warehouse

Grabowski, Timothy B.

2016-01-01

Burbot Lota lota is the sole freshwater representative of the cod-like fishes and supports subsistence, commercial, and recreational fisheries worldwide above approximately 40° N. It is a difficult species to manage effectively due to its preference for deep-water habitats and spawning activity under the ice in winter. Like other gadiform fishes, Burbot use acoustic signaling as part of their mating system, and while the acoustic repertoire of the species has been characterized under artificial conditions (i.e., net pen suspended under ice in a natural lake), there has been no work to determine whether the species is as vocal in natural spawning aggregations. Our objective was to assess the feasibility of collecting and using acoustic data to characterize the spawning activity and locations of Burbot under field conditions. We recorded audio and video of Burbot spawning aggregations through holes drilled into the ice at known spawning grounds at Moyie Lake in British Columbia, Canada. Acoustic recordings (call counts and audiograms) were analyzed using Raven Pro v 1. 4 software. Acoustic behavior was also related to video data to determine how acoustic activity correlated to any observed spawning behavior. In general, wild Burbot spawning in Moyie Lake did not vocalize as frequently as counterparts spawning under artificial conditions. Further, Burbot vocalizations were not recorded in conjunction with spawning activity. While it may be feasible to use passive acoustic monitoring to locate Burbot spawning grounds and identify periods of activity, it does not seem to hold much promise for locating and quantifying spawning activity in real time.

Differential metabolite levels in response to spawning-induced inappetence in Atlantic salmon Salmo salar.

PubMed

Cipriano, Rocco C; Smith, McKenzie L; Vermeersch, Kathleen A; Dove, Alistair D M; Styczynski, Mark P

2015-03-01

Atlantic salmon Salmo salar undergo months-long inappetence during spawning, but it is not known whether this inappetence is a pathological state or one for which the fish are adapted. Recent work has shown that inappetent whale sharks can exhibit circulating metabolite profiles similar to ketosis known to occur in humans during starvation. In this work, metabolite profiling was used to explore differences in analyte profiles between a cohort of inappetent spawning run Atlantic salmon and captively reared animals that were fed up to and through the time of sampling. The two classes of animals were easily distinguished by their metabolite profiles. The sea-run fish had elevated ɷ-9 fatty acids relative to the domestic feeding animals, while other fatty acid concentrations were reduced. Sugar alcohols were generally elevated in inappetent animals, suggesting potentially novel metabolic responses or pathways in fish that feature these compounds. Compounds expected to indicate a pathological catabolic state were not more abundant in the sea-run fish, suggesting that the animals, while inappetent, were not stressed in an unnatural way. These findings demonstrate the power of discovery-based metabolomics for exploring biochemistry in poorly understood animal models. Copyright © 2015 Elsevier Inc. All rights reserved.

76 FR 16698 - Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; Shrimp Fishery Off the Southern...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-25

... severely depleted by unusually cold weather conditions. DATES: The closure is effective March 22, 2011... shrimp spawning stock that has been severely depleted by cold weather. Consistent with those procedures... time and would potentially further harm the spawning stock that has been impacted due to cold weather...

Low impact of exposure to environmentally relevant doses of 226Ra in Atlantic cod (Gadus morhua) embryonic cells.

PubMed

Olsvik, Pål A; Berntssen, Marc H G; Hylland, Ketil; Eriksen, Dag Ø; Holen, Elisabeth

2012-07-01

The aim of this study was to investigate whether (226)Ra, a radionuclide present in produced water from oil platforms in the North Sea and other offshore drilling areas, could affect vulnerable early life stages of Atlantic cod (Gadus morhua). Blastula-stage embryonic cells (EC) from fertilized eggs of Atlantic cod were isolated and exposed to environmental relevant concentrations of (226)Ra and transcription of selected genes quantified. The results showed a weak, but significant up-regulation of GPx3 and HSP70 transcripts after 48 h of exposure to 2.11 Bq/L. In EC exposed to three (226)Ra concentrations (2.11, 23 and 117 Bq/L) for 12 h, metallothionein, HSP90AA, thioredoxin and caspase 8 were significantly up-regulated in cells exposed to 117 Bq/L, whereas thioredoxin was also significantly up-regulated in EC exposed to 23 Bq/L. When EC were exposed to the same (226)Ra concentrations for 48 h, only heme oxygenase was significantly up-regulated in the 23 Bq/L exposure group. The results suggest that environmentally relevant activities of (226)Ra may induce oxidative stress and apoptosis in fish ECs. Exposure of Atlantic cod EC to Cd, selected as a model toxicant, supported the ability of EC around blastula stage to respond to toxicants by altered transcription. Due to dilution, environmentally relevant concentrations of radionuclides present in produced water would be expected to pose a minor threat to early life stages of fish. Copyright © 2012 Elsevier Ltd. All rights reserved.

An evaluation of the duration of efficacy of emamectin benzoate in the control of Caligus curtus Müller infestations in Atlantic cod, Gadus morhua L.

PubMed

Hamre, L A; Lunestad, B T; Hannisdal, R; Samuelsen, O B

2011-06-01

The duration of efficacy of emamectin benzoate in the control of Caligus curtus infestations in Atlantic cod, Gadus morhua L., was studied following an administration of 50 μg kg⁻¹ for seven consecutive days. No lice were found on medicated fish when challenged 1 week (challenge 1) or 5 weeks (challenge 2) following termination of medication, whereas the mean abundance of lice among the unmedicated fish was 17.9 and 19.3 lice per fish in challenge 1 and 2, respectively. Muscle concentrations of 19.5 ± 8.2 ng g⁻¹ and 3.4 ± 0.9 ng g⁻¹, respectively, and skin concentrations of 23.1 ± 10.8 and 4.2 ± 1.0 ng g⁻¹, respectively, were found 27 and 55 days following the termination of medication. Tissue concentrations and the duration of efficacy indicate a dosing regime for emamectin in cod, similar to the regime used for Atlantic salmon, Salmo salar L. © 2011 Blackwell Publishing Ltd.

Exophiala angulospora causes systemic inflammation in atlantic cod Gadus morhua.

PubMed

Gjessing, Mona Cecilie; Davey, Marie; Kvellestad, Agnar; Vrålstad, Trude

2011-10-06

Species of Exophiala are opportunistic fungal pathogens that may infect a broad range of warm- and cold-blooded animals, including salmonids and Atlantic cod. In the present study, we observed abnormal swimming behaviour and skin pigmentation and increased mortality in cod kept in an indoor tank. Necropsy revealed foci of different sizes with a greyish to brownish colour in internal organs of diseased fish. The foci consisted of ramifying darkly pigmented fungal hyphae surrounded by distinct layers of inflammatory cells, including macrophage-like cells. In the inner layer with many hyphae, the macrophage-like cells were dead. We observed no apparent restriction of fungal growth by the inflammatory response. A darkly pigmented fungus was repeatedly isolated in pure culture from foci of diseased fish and identified as Exophiala angulospora using morphological and molecular characters. This species has not been previously reported to cause disease in cod, but has been reported as an opportunistic pathogen of both marine and freshwater fish. Based on the morphology and sequence analysis presented here, we conclude that E. angulospora caused the observed chronic multifocal inflammation in internal organs of cod, leading to severe disease and mortality.

Temporal variations in the fecundity of Arcto-Norwegian cod ( Gadus morhua) in response to natural changes in food and temperature

NASA Astrophysics Data System (ADS)

Kjesbu, O. S.; Witthames, P. R.; Solemdal, P.; Greer Walker, M.

1998-12-01

Sexually mature Arcto-Norwegian female cod, Gadus morhua, were sampled off northern Norway either during spawning migration (Vesterålen) or at spawning sites (Lofoten) from 1986 to 1996. This period comprised a dramatic, nearly cyclical change in the Barents Sea ecosystem. The stock of the main food item, viz. the Barents Sea capelin Mallotus villosus villosus, changed from a low (1986), to a high (1991) and again to a low (1994) level of abundance while the climate changed from a cold (≤1989) to a warm regime. The relative annual potential fecundity (i.e. number of vitellogenic oocytes per g prespawning fish) increased by approximately 40% from 1987 to 1991. However, information from a back-calculation technique calibrated in the laboratory using spawning fish indicated that this change might have been as high as 80 to 90%. Ovaries were analysed by the gravimetric, the automated particle counting and the stereometric method (modified to use with ovaries too large to section whole). All three methods gave similar fecundity estimates. The latter method was applied to quantify atresia of developing oocytes in the good-condition year of 1991. Atresia was rare, occurring in only 30% of the ovaries and where it was present in only 1 to 4% of the vitellogenic oocytes. Spawning females sampled from 1991 to 1996 gradually produced fewer eggs and demonstrated clear interannual variations in vitellogenic oocyte mean size and distribution thought to reflect a delicate reproductive tactic to minimise negative nutritional effects on egg size and egg quality. Estimates of annual potential fecundity for the duration of the study were significantly positively correlated with environmental temperature and the availability of capelin during vitellogenesis.

Phenotypic flexibility of digestive system in Atlantic cod (Gadus morhua).

PubMed

Blier, P U; Dutil, J-D; Lemieux, H; Bélanger, F; Bitetera, L

2007-02-01

This study examined the restoration of the digestive capacity of Atlantic cod (Gadus morhua Linnaeus) following a long period of food deprivation. Fifty cod (48 cm, 1 kg) were food-deprived for 68 days and then fed in excess with capelin (Mallotus villosus Müller) on alternate days. Ten fish were sampled after 0, 2, 6, 14 and 28 days and the mass of the pyloric caeca, intestine and carcass determined. Two metabolic enzymes (cytochrome c oxidase and citrate synthase) were assayed in white muscle, pyloric caeca and intestine, and trypsin activity was measured in the pyloric caeca. A delay of 14 days was required before body mass started to increase markedly, whereas most of the increase in mass of both the pyloric caeca and intestine relative to fish length occurred earlier in the experiment. By day 14, the activities of trypsin and citrate synthase in the pyloric caeca as well as citrate synthase in the intestine had reached maxima. The growth of the digestive tissues and restoration of their metabolic capacities thus occur early upon refeeding and are likely required for recovery growth to take place. The phenotypic flexibility of the cod digestive system is therefore remarkable: increases in trypsin activity and size of pyloric caeca resulted in a combined 29-fold increase in digestive capacity of the fish during the refeeding period. Our study suggests that Atlantic cod are able to cope with marked fluctuations in food availability in their environment by making a rapid adjustment of their digestive capacity as soon as food availability increases.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Atlantic)

DTIC Science & Technology

1989-01-01

species prey of other fishes and is a of Cynoscion. For specimens at least seasonally important component of 6 mm SL, spot have more anal fin estuarine and...spawning occurs over the outer 17.5-25.0 *C. Warlen and Chester shelf throughout most of the spawning (1985) collected young larvae (< 16 season but...over the mid-shelf early days old) only at water temperatures and late in the spawning season higher than 19.3 *C. Fahay (1975) (Warlen and Chester

Assessing the Influence of Hydrological Connectivity on the Spawning Migration of Atlantic Salmon.

NASA Astrophysics Data System (ADS)

Lazzaro, G.; Soulsby, C.; Tetzlaff, D.; Botter, G.

2016-12-01

Atlantic salmon is an economically and ecologically important fish species, whose survival is critically impacted by successful spawning in headwater gravel-bed rivers. Streamflow dynamics may have a strong control on spawning because adult fish require sufficiently high discharges to move upriver and reach spawning sites. We present a simple outflux-influx model linking the number of female salmon emigrating (i.e. outflux) and returning (i.e. influx) to a small spawning stream in Scotland (the Girnock Burn). The model explicitly accounts for the inter-annual variability of the hydrologic regime and its influence on hydrological connectivity. Model results are then compared against a unique long-term hydro-ecological dataset that includes annual fluxes of immigrant and emigrant salmon and daily discharges for about 40 years. The satisfactory model results confirm that hydrologic variability contributes significantly to the observed dynamics of salmon returns to the Girnock, with a good correlation between the positive (negative) peaks in the immigration dataset and the exceedance (non-exceedance) probability of a threshold flow (0.3 m3/s). Importantly, model performance deteriorates when the inter-annual variability of flow regime is disregarded. The analysis suggests that the hydrological connectivity represents a key feature of riverine systems, which needs to be carefully considered in settings where flow regimes are altered by water abstractions or diversions.

Delineating recurrent fish spawning habitats in the North Sea

NASA Astrophysics Data System (ADS)

Lelièvre, S.; Vaz, S.; Martin, C. S.; Loots, C.

2014-08-01

The functional value of spawning habitats makes them critically important for the completion of fish life cycles and spawning grounds are now considered to be “essential habitats”. Inter-annual fluctuations in spawning ground distributions of dab (Limanda Limanda), plaice (Pleuronectes platessa), cod (Gadus morhua) and whiting (Merlangius merlangus) were investigated in the southern North Sea and eastern English Channel, from 2006 to 2009. The preferential spawning habitats of these species were modelled using generalised linear models, with egg distribution being used as proxy of spawners' location. Egg spatial and temporal distributions were explored based on six environmental variables: sea surface temperature and salinity, chlorophyll a concentration, depth, bedstress and seabed sediment types. In most cases, egg density was found to be strongly related to these environmental variables. Egg densities were positively correlated with shallow to intermediate depths having low temperature and relatively high salinity. Habitat models were used to map annual, i.e. 2006 to 2009, winter spatial distributions of eggs, for each species separately. Then, annual maps were combined to explore the spatial variability of each species' spawning grounds, and define recurrent, occasional, rare and unfavourable spawning areas. The recurrent spawning grounds of all four species were located in the south-eastern part of the study area, mainly along the Dutch and German coasts. This study contributes knowledge necessary to the spatial management of fishery resources in the area, and may also be used to identify marine areas with particular habitat features that need to be preserved.

Offshore wind farms as productive sites or ecological traps for gadoid fishes?--impact on growth, condition index and diet composition.

PubMed

Reubens, Jan T; Vandendriessche, Sofie; Zenner, Annemie N; Degraer, Steven; Vincx, Magda

2013-09-01

With the construction of wind farms all across the North Sea, numerous artificial reefs are created. These windmill artificial reefs (WARs) harbour high abundances of fish species which can be attracted from elsewhere or can be the result of extra production induced by these wind farms. To resolve the attraction-production debate in suddenly altered ecosystems (cf. wind farms), the possible consequences of attraction should be assessed; thereby bearing in mind that ecological traps may arise. In this paper we investigated whether the wind farms in the Belgian part of the North Sea act as ecological traps for pouting and Atlantic cod. Length-at-age, condition and diet composition of fish present at the windmill artificial reefs was compared to local and regional sandy areas. Fish data from the period 2009-2012 were evaluated. Mainly I- and II-group Atlantic cod were present around the WARs; while the 0- and I-group dominated for pouting. For Atlantic cod, no differences in length were observed between sites, indicating that fitness was comparable at the WARs and in sandy areas. No significant differences in condition index were observed for pouting. At the WARs, they were slightly larger and stomach fullness was enhanced compared to the surrounding sandy areas. Also diet differed considerably among the sites. The outcome of the proxies indicate that fitness of pouting was slightly enhanced compared to the surrounding sandy areas. No evidence was obtained supporting the hypothesis that the WARs act as an ecological trap for Atlantic cod and pouting. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of reproductive status in Atlantic Tripletail by traditional and nonlethal approaches

USGS Publications Warehouse

Parr, R. T.; Jennings, Cecil A.; Denslow, N. D.; Kroll, K.J.; Bringolf, R.B.

2016-01-01

Reproductive biology information is an important tool for fishery management actions such as the identification of spawning areas and the development of protective size limits, bag limits, and seasons. Such information for the management of Atlantic TripletailLobotes surinamensis is currently limited, particularly in the western Atlantic Ocean, as information regarding the reproductive biology of this species is sparse in the published literature. To this end, we determined the reproductive status of tripletail and compared the results of a nonlethal sampling method, plasma vitellogenin (VTG) analysis, with those of two traditional (lethal) methods, gonadosomatic index (GSI) and gonad histology. A total of 223 (122 male and 101 female) tripletail were sampled over 2 years near Jekyll Island, Georgia. Gonad histology indicated that 107 (94%) of the male tripletail were in the spawning-capable reproductive phase. Female tripletail were found in all reproductive phases, but only nine (8.9%) were in the spawning-capable phase. Plasma VTG was strongly related to GSI in females (R2 = 0.832, n = 77), and female GSI differed significantly among reproductive phases (p < 0.0001). The estimated length at which 50% (L50) of female tripletail reached maturity was 463 mm; however, the L50 for male tripletail could not be determined because of the lack of immature fish within the study sample. Our study provides valuable information for the management of tripletail and indicates that a nonlethal approach (plasma VTG) may be useful for differentiating developing and spawning-capable females from males and from females in other reproductive phases.

Electronic Tagging of Atlantic Bluefin Tuna (Thunnus thynnus, L.) Reveals Habitat Use and Behaviors in the Mediterranean Sea

PubMed Central

Cermeño, Pablo; Quílez-Badia, Gemma; Ospina-Alvarez, Andrés; Sainz-Trápaga, Susana; Boustany, Andre M.; Seitz, Andy C.; Tudela, Sergi; Block, Barbara A.

2015-01-01

We analyzed the movements of Atlantic tuna (Thunnus thynnus L.) in the Mediterranean Sea using data from 2 archival tags and 37 pop-up satellite archival tags (PAT). Bluefin tuna ranging in size from 12 to 248 kg were tagged on board recreational boats in the western Mediterranean and the Adriatic Sea between May and September during two different periods (2000 to 2001 and 2008 to 2012). Although tuna migrations between the Mediterranean Sea and the Atlantic Ocean have been well reported, our results indicate that part of the bluefin tuna population remains in the Mediterranean basin for much of the year, revealing a more complex population structure. In this study we demonstrate links between the western Mediterranean, the Adriatic and the Gulf of Sidra (Libya) using over 4336 recorded days of location and behavior data from tagged bluefin tuna with a maximum track length of 394 days. We described the oceanographic preferences and horizontal behaviors during the spawning season for 4 adult bluefin tuna. We also analyzed the time series data that reveals the vertical behavior of one pop-up satellite tag recovered, which was attached to a 43.9 kg tuna. This fish displayed a unique diving pattern within 16 days of the spawning season, suggesting a use of the thermocline as a thermoregulatory mechanism compatible with spawning. The results obtained hereby confirm that the Mediterranean is clearly an important habitat for this species, not only as spawning ground, but also as an overwintering foraging ground. PMID:25671316

A Unified Approach to Passive and Active Ocean Acoustic Waveguide Remote Sensing

DTIC Science & Technology

2012-09-30

acoustic sensing reveals humpback whale behavior synchronous with herring spawning processes and sonar had no effect on humpback song ,” submitted to...source and receiver arrays to enable instantaneous continental-shelf scale imaging and continuous monitoring of fish and whale populations. Acoustic...Preliminary analysis shows that humpback whale behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of

Earth observations taken from shuttle orbiter Atlantis during STS-84 mission

NASA Image and Video Library

1997-07-09

STS084-703-003 (15-24 May 1997) --- Cape Cod extends 105 kilometers (65 miles) into the Atlantic Ocean. To the south of Cape Cod are the islands of Martha's Vineyard (west) and Nantucket (east). The city of Boston can be seen surrounding the bay above the "hook" on Cape Cod. To the south are the cities of New Bedford on Buzzards Bay, and Providence, Rhode Island. The Cape Cod Canal is an artificial waterway that connects Buzzards Bay and Cape Cod Bay. The waterway is 28 kilometers (17.5 miles) and does not contains locks. The canal was built to shorten the distance over water between New York City and Boston. In 1620 the Pilgrims landed at Provincetown, on the upper tip of Cape Cod, before they proceeded to Plymouth.

LATITUDINAL GRADIENTS IN BENTHIC COMMUNITY COMPOSITION IN WESTERN ATLANTIC ESTUARIES

EPA Science Inventory

The community structure of benthic macroinvertebrates from estuaries along the Atlantic coast of North America from Cape Cod, MA, to Biscayne Bay, FL, were compared. Benthic data were collected over a 5 year period (1990 to 1995) by the U.S. Environmental Protection Agency's Envi...

Quality assessment of wild Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) semen under conditions of short-term storage

USDA-ARS?s Scientific Manuscript database

Short-term storage trials were conducted with Atlantic sturgeon semen collected from a total of nine wild males during the 2008 and 2009 spawning seasons on the Hudson River. Semen samples were kept refrigerated (4 plus or minus 1 degree C) and stored in different gaseous atmospheres and storage ext...

Interoceanic differences in the reproduction of coral-reef fishes.

PubMed

Thresher, R E

1982-10-01

Eggs of demersal spawning coral-reef fishes of the tropical western Atlantic are smaller than those of related species in the western Pacific. Decreased egg volume may result in increased fecundity per unit body weight of Atlantic species, a factor that may underlie apparent differences in the stability of the respective coral-reef fish communities.

Daily variation in ingress of fall-spawned larval fishes into Delaware Bay in relation to alongshore and along-estuary wind components

NASA Astrophysics Data System (ADS)

Schieler, Brittany M.; Hale, Edward A.; Targett, Timothy E.

2014-12-01

Identifying factors that affect ingress of larval fishes from offshore spawning areas into estuarine nurseries is important to improve understanding of variability in recruitment of many coastal marine species. This study investigated the ingress of larval Atlantic croaker (Micropogonias undulatus), Atlantic menhaden (Brevoortia tyrannus), and summer flounder (Paralichthys dentatus) at Roosevelt Inlet, near the mouth of Delaware Bay, USA in relation to short-term wind events. Nightly abundances, from November 15 to December 15, 2010, were analyzed with alongshore and along-estuary wind components (direction and speed) using cross-correlation analysis to determine if winds affect larval ingress. Ingress of Atlantic croaker and summer flounder correlated with along-estuary winds, whereas Atlantic menhaden showed no significant correlations with either alongshore or along-estuary winds. Although along-estuary winds during this period were predominantly down-estuary, Atlantic croaker ingress was correlated with positive along-estuary winds (blowing up-estuary), with a three-day lag; and a particularly large ingress peak occurred following the largest up-estuary wind peak. Ingress of summer flounder was correlated with negative along-estuary winds (blowing down-estuary), with a two-day lag. These results suggest that species-specific vertical position in the water column influenced ingress into Delaware Bay. The lag results also suggest that ingressing Atlantic croaker and summer flounder may have a pooling stage outside the mouth of Delaware Bay.

ECOLOGICAL CONDITION OF THE ESTUARIES OF THE ATLANTIC AND GULF COASTS OF THE UNITED STATES.

EPA Science Inventory

Monitoring the estuaries of the Atlantic and Gulf of Mexico coastlines from Cape Cod, MA to Brownsville, TX was performed annually from 1990-1997 to assess ecological conditions on a regional basis for four biogeographic provinces. These province estimates - Virginian, Carolinia...

CHARACTERIZATION OF WESTERN NORTH ATLANTIC RIGHT WHALE SPRING FEEDING HABITAT

EPA Science Inventory

The Great South Channel region of the southwestern Gulf of Maine, between George's Bank and Cape Cod, is the primary spring feeding ground for the western North Atlantic population of the I northern right whale, E. glacialis .Since this whale is so endangered, it is critical to i...

78 FR 35217 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; American Lobster Fishery

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-12

.... 080219213-3470-01] RIN 0648-AT31 Atlantic Coastal Fisheries Cooperative Management Act Provisions; American... lobster trap fishery in Lobster Conservation Management Area 2 (Federal nearshore waters in Southern New England; Area 2), and in the Outer Cape Cod Lobster Conservation Management Area (Federal nearshore waters...

Seasonal dynamics of Atlantic herring (Clupea harengus L.) populations spawning in the vicinity of marginal habitats.

PubMed

Eggers, Florian; Slotte, Aril; Libungan, Lísa Anne; Johannessen, Arne; Kvamme, Cecilie; Moland, Even; Olsen, Esben M; Nash, Richard D M

2014-01-01

Gillnet sampling and analyses of otolith shape, vertebral count and growth indicated the presence of three putative Atlantic herring (Clupea harengus L.) populations mixing together over the spawning season February-June inside and outside an inland brackish water lake (Landvikvannet) in southern Norway. Peak spawning of oceanic Norwegian spring spawners and coastal Skagerrak spring spawners occurred in March-April with small proportions of spawners entering the lake. In comparison, spawning of Landvik herring peaked in May-June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal habitat. The 1.85 km(2) lake was characterized by oxygen depletion occurring between 2.5 and 5 m depth between March and June. This was followed by changes in salinity from 1-7‰ in the 0-1 m surface layer to levels of 20-25‰ deeper than 10 m. In comparison, outside the 3 km long narrow channel connecting the lake with the neighboring fjord, no anoxic conditions were found. Here salinity in the surface layer increased over the season from 10 to 25‰, whereas deeper than 5 m it was stable at around 35‰. Temperature at 0-5 m depth increased significantly over the season in both habitats, from 7 to 14 °C outside and 5 to 17 °C inside the lake. Despite differences in peak spawning and utilization of the lake habitat between the three putative populations, there was an apparent temporal and spatial overlap in spawning stages suggesting potential interbreeding in accordance with the metapopulation concept.

Migratory salmonid redd habitat characteristics in the Salmon River, New York

USGS Publications Warehouse

Johnson, James H.; Nack, Christopher C.; McKenna, James E.

2010-01-01

Non-native migratory salmonids ascend tributaries to spawn in all the Great Lakes. In Lake Ontario, these species include Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), steelhead (O. mykiss), and brown trout (Salmo trutta). Although successful natural reproduction has been documented for many of these species, little research has been conducted on their spawning habitat. We examined the spawning habitat of these four species in the Salmon River, New York. Differences in fish size among the species were significantly correlated with spawning site selection. In the Salmon River, the larger species spawned in deeper areas with larger size substrate and made the largest redds. Discriminant function analysis correctly classified redds by species 64–100% of the time. The size of substrate materials below Lighthouse Hill Dam is within the preferred ranges for spawning for these four species indicating that river armoring has not negatively impacted salmonid production. Intra-specific and inter-specific competition for spawning sites may influence redd site selection for smaller salmonids and could be an impediment for Atlantic salmon (S. salar) restoration.

Causes and projections of abrupt climate-driven ecosystem shifts in the North Atlantic.

PubMed

Beaugrand, Grégory; Edwards, Martin; Brander, Keith; Luczak, Christophe; Ibanez, Frederic

2008-11-01

Warming of the global climate is now unequivocal and its impact on Earth' functional units has become more apparent. Here, we show that marine ecosystems are not equally sensitive to climate change and reveal a critical thermal boundary where a small increase in temperature triggers abrupt ecosystem shifts seen across multiple trophic levels. This large-scale boundary is located in regions where abrupt ecosystem shifts have been reported in the North Atlantic sector and thereby allows us to link these shifts by a global common phenomenon. We show that these changes alter the biodiversity and carrying capacity of ecosystems and may, combined with fishing, precipitate the reduction of some stocks of Atlantic cod already severely impacted by exploitation. These findings offer a way to anticipate major ecosystem changes and to propose adaptive strategies for marine exploited resources such as cod in order to minimize social and economic consequences.

Rested and stressed farmed Atlantic cod (Gadus morhua) chilled in ice or slurry and effects on quality.

PubMed

Digre, Hanne; Erikson, Ulf; Aursand, Ida G; Gallart-Jornet, Lorena; Misimi, Ekrem; Rustad, Turid

2011-01-01

The main objectives of this study were to investigate (1) whether rested harvest of farmed cod was better maintained by chilling with slurry rather than by traditional ice storage, (2) whether chilling with slurry would be a feasible chilling method to assure low core temperatures (≤0 °C) at packing of gutted fish, and (3) the effects of superchilling compared with traditional ice on selected quality parameters of cod during storage. In the experiment, seawater slurry at -2.0 ± 0.3 °C was used. Anesthetized (AQUI-S™), percussion stunned, and stressed cod chilled in slurry were compared. Cod stored on ice were used as reference group. The fish were evaluated at the day of slaughter, and after 7 and 14 d of storage according to handling stress (initial muscle pH, muscle twitches, rigor mortis), core temperatures, quality index method, microbial counts, weight changes, salt and water content, water distribution, pH, adenosine triphosphate-degradation products, K-value, water-holding capacity, fillet color, and texture. Chilling cod in slurry was more rapid than chilling in ice. Prechilling (1 d) of cod in slurry before subsequent ice storage resulted in lower quality 7 d postmortem compared with both ice and continuous slurry storage. The potential advantages of superchilling became more prominent after 14 d with lower microbiological activity, better maintenance of freshness (lower total quality index scores and lower K-values) compared with fish stored on ice. A drawback with slurry-stored fish was that cloudy eyes developed earlier, in addition to weight gain and salt uptake compared to ice-stored fish. Practical Application: Chilling is an essential operation in any fish-processing plant. This manuscript addresses different applications of slurry ice in the processing and storage of Atlantic cod. Cod quality was assessed after 7 and 14 d of iced and superchilled storage.

Levels of synthetic antioxidants (ethoxyquin, butylated hydroxytoluene and butylated hydroxyanisole) in fish feed and commercially farmed fish.

PubMed

Lundebye, A-K; Hove, H; Måge, A; Bohne, V J B; Hamre, K

2010-12-01

Several synthetic antioxidants are authorized for use as feed additives in the European Union. Ethoxyquin (EQ) and butylated hydroxytoluene (BHT) are generally added to fish meal and fish oil, respectively, to limit lipid oxidation. The study was conducted to examine the concentrations of EQ, BHT and butylated hydroxyanisole (BHA) in several commercially important species of farmed fish, namely Atlantic salmon, halibut and cod and rainbow trout, as well as concentrations in fish feed. The highest levels of BHT, EQ and BHA were found in farmed Atlantic salmon fillets, and were 7.60, 0.17 and 0.07 mg kg(-1), respectively. The lowest concentrations of the synthetic antioxidants found were in cod. The concentration of the oxidation product ethoxyquin dimer (EQDM) was more than ten-fold higher than the concentration of parent EQ in Atlantic salmon halibut and rainbow trout, whereas this dimer was not detected in cod fillets. The theoretical consumer exposure to the synthetic antioxidants EQ, BHA and BHT from the consumption of farmed fish was calculated. The contribution of EQ from a single portion (300 g) of skinned fillets of the different species of farmed fish would contribute at most 15% of the acceptable daily intake (ADI) for a 60 kg adult. The consumption of farmed fish would not contribute measurably to the intake of BHA; however, a 300 g portion of farmed Atlantic salmon would contribute up to 75% of the ADI for BHT.

Measuring abnormal movements in free-swimming fish with accelerometers: implications for quantifying tag and parasite load.

PubMed

Broell, Franziska; Burnell, Celene; Taggart, Christopher T

2016-03-01

Animal-borne data loggers allow movement, associated behaviours and energy expenditure in fish to be quantified without direct observations. As with any tagging, tags that are attached externally may adversely affect fish behaviour, swimming efficiency and survival. We report on free-swimming wild Atlantic cod (Gadus morhua) held in a large mesocosm that exhibited distinctly aberrant rotational swimming (scouring) when externally tagged with accelerometer data loggers. To quantify the phenomenon, the cod were tagged with two sizes of loggers (18 and 6 g; <2% body mass) that measured tri-axial acceleration at 50 Hz. An automated algorithm, based on body angular rotation, was designed to extract the scouring movements from the acceleration signal (98% accuracy). The algorithm also identified the frequency pattern and associated energy expenditure of scouring in relation to tag load (% body weight). The average per cent time spent scouring (5%) was independent of tag load. The vector of the dynamic body acceleration (VeDBA), used as a proxy for energy expenditure, increased with tag load (r(2)=0.51), and suggests that fish with large tags spent more energy when scouring than fish with small tags. The information allowed us to determine potential detrimental effects of an external tag on fish behaviour and how these effects may be mitigated by tag size. The algorithm can potentially identify similar rotational movements associated with spawning, courtship, feeding and parasite-load shedding in the wild. The results infer a more careful interpretation of data derived from external tags and the careful consideration of tag type, drag, buoyancy and placement, as well as animal buoyancy and species. © 2016. Published by The Company of Biologists Ltd.

Traveling around Cape Horn: Otolith chemistry reveals a mixed stock of Patagonian hoki with separate Atlantic and Pacific spawning grounds

USGS Publications Warehouse

Schuchert, P.C.; Arkhipkin, A.I.; Koenig, A.E.

2010-01-01

Trace element fingerprints of edge and core regions in otoliths from 260 specimens of Patagonian hoki, Macruronus magellanicus L??nnberg, 1907, were analyzed by LA-ICPMS to reveal whether this species forms one or more population units (stocks) in the Southern Oceans. Fish were caught on their spawning grounds in Chile and feeding grounds in Chile and the Falkland Islands. Univariate and multivariate analyses of trace element concentrations in the otolith edges, which relate to the adult life of fish, could not distinguish between Atlantic (Falkland) and Pacific (Chile) hoki. Cluster analyses of element concentrations in the otolith edges produced three different clusters in all sample areas indicating high mixture of the stocks. Cluster analysis of trace element concentrations in the otolith cores, relating to juvenile and larval life stages, produced two separate clusters mainly distinguished by 137Ba concentrations. The results suggest that Patagonian hoki is a highly mixed fish stock with at least two spawning grounds around South America. ?? 2009 Elsevier B.V.

Distribution of spawning activity by anadromous fishes in an atlantic slope drainage after removal of a low-head dam

USGS Publications Warehouse

Burdick, S.M.; Hightower, J.E.

2006-01-01

In 1998, the Quaker Neck Dam was removed from the Neuse River near Goldsboro, North Carolina, restoring access to more than 120 km of potential main-stem spawning habitat and 1,488 km of potential tributary spawning habitat to anadromous fishes. We used plankton sampling and standardized electrofishing to examine the extent to which anadromous fishes utilized this restored spawning habitat in 2003 and 2004. Evidence of spawning activity was detected upstream of the former dam site for three anadromous species: American shad Alosa sapidissima, hickory shad A. mediocris, and striped bass Morone saxatilis. The percentages of eggs and larvae collected in the restored upstream habitat were greater in 2003, when spring flows were high, than in 2004. River reaches where spawning occurred were estimated from egg stage and water velocity data. Spawning of American shad and striped bass occurred primarily in main-stem river reaches that were further upstream during the year of higher spring flows. Hickory shad generally spawned in downstream reaches and in tributaries above and below the former dam site. These results demonstrate that anadromous fishes will take advantage of upper basin spawning habitat restored through dam removal as long as instream flows are adequate to facilitate upstream migration.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). Bay Anchovy

DTIC Science & Technology

1989-02-01

Mexico coasts, from Cape Cod, species of anchovies have been Massachusetts, to Yucatan , Mexico recorded from the Mid-Atlantic Region, (Hildebrand 1963...bay anchovies were food web (Figure 3). It is an apparently unaffected by water important source of nutrition for many temperatures exceeding 32 0 C

Ecological Condition of Coastal Ocean Waters Along the U.S. Mid-Atlantic Bight: 2006

EPA Science Inventory

This report presents the results of an assessment of ecological condition in coastal-ocean waters of the U.S. mid-Atlantic Bight (MAB), along the U.S. continental shelf from Cape Cod, MA and Nantucket Shoals to the northeast to Cape Hatteras to the south, based on sampling conduc...

Harvesting Atlantic Cod under Climate Variability

NASA Astrophysics Data System (ADS)

Oremus, K. L.

2016-12-01

Previous literature links the growth of a fishery to climate variability. This study uses an age-structured bioeconomic model to compare optimal harvest in the Gulf of Maine Atlantic cod fishery under a variable climate versus a static climate. The optimal harvest path depends on the relationship between fishery growth and the interest rate, with higher interest rates dictating greater harvests now at the cost of long-term stock sustainability. Given the time horizon of a single generation of fishermen under assumptions of a static climate, the model finds that the economically optimal management strategy is to harvest the entire stock in the short term and allow the fishery to collapse. However, if the biological growth of the fishery is assumed to vary with climate conditions, such as the North Atlantic Oscillation, there will always be pulses of high growth in the stock. During some of these high-growth years, the growth of the stock and its economic yield can exceed the growth rate of the economy even under high interest rates. This implies that it is not economically optimal to exhaust the New England cod fishery if NAO is included in the biological growth function. This finding may have theoretical implications for the management of other renewable yet exhaustible resources whose growth rates are subject to climate variability.

Juvenile Atlantic cod behavior appears robust to near-future CO2 levels.

PubMed

Jutfelt, Fredrik; Hedgärde, Maria

2015-01-01

Ocean acidification caused by the anthropogenic release of CO2 is considered a major threat to marine ecosystems. One unexpected impact of elevated water CO2 levels is that behavioral alterations may occur in tropical reef fish and certain temperate fish species. These effects appear to alter many different types of sensory and cognitive functions; if widespread and persistent, they have the potential to cause ecosystem changes. We investigated whether economically and ecologically important Atlantic cod also display behavioral abnormalities by exposing 52 juvenile cod to control conditions (500 μatm, duplicate tanks) or an end-of-the-century ocean acidification scenario (1000 μatm, duplicate tanks) for one month, during which time the fish were examined for a range of behaviors that have been reported to be affected by elevated CO2 in other fish. The behaviors were swimming activity, as measured by number of lines crossed per minute, the emergence from shelter, determined by how long it took the fish to exit a shelter after a disturbance, relative lateralization (a measure of behavioral turning side preference), and absolute lateralization (the strength of behavioral symmetry). We found no effect of CO2 treatment on any of the four behaviors tested: activity (F = 1.61, p = 0.33), emergence from shelter (F = 0.13, p = 0.76), relative lateralization (F = 2.82, p = 0.50), and absolute lateralization (F = 0.80, p = 0.26). Our results indicate that the behavior of Atlantic cod could be resilient to the impacts of near-future levels of water CO2.

Gulf of Mexico Ecological Forecasting - Atlantic Bluefin Tuna Population Assessment and Management using Synthetic Aperture Radar (SAR) Data

NASA Astrophysics Data System (ADS)

Laygo, K.; Jones, I.; Huerta, J.; Holt, B.

2010-12-01

Atlantic Bluefin Tuna (Thunnus thynnus) is one of the largest vertebrates in the world and is in high demand in sushi markets. It is a highly political species and is managed internationally by the International Commission for the Conservation of Atlantic Tuna. The Gulf of Mexico and the Mediterranean Sea are the only two known spawning sites in the world. However, there is a large variance in estimates of adult Atlantic Tuna spawning. This research focuses on extending Earth science research results to existing decision-making systems, National Oceanic and Atmospheric Administration (NOAA) and the National Marine Fisheries Service (NMFS)for population assessment and management of Atlantic Bluefin Tuna. The research team is a multi-sector and multi-disciplinary team composed of government (NOAA_NMFS), academic (University of South Florida Institute for Marine Remote Sensing) and commercial (Roffer’s Ocean Fishing Forecasting Service, Inc.) institutions. Their goal is to reduce the variance in the estimates of adult Bluefin Tuna spawning stock abundance in the Gulf of Mexico (GOM). Therefore, this paper will be derived from the innovative use of several earth orbiting satellites focusing on the use of synthetic aperture radar (SAR) data to identify Sargassum, which is a floating marine algae that may be relevant to the presence of Bluefin Tuna aggregations. The SAR imagery will be examined in combination with MODIS and MERIS Chlorophyll-a products to detect fine-scale surface current shear, eddy and frontal features, as well as biological slicks due to the presence of Sargassum. In addition, wind records from NOAA buoy data will be studied to analyze wind patterns in the Gulf of Mexico. The fine-resolution, all-weather capabilities of SAR provide a valuable complement to optical/IR sensors, which are often impacted by cloud cover. This study will provide an assessment of whether or not SAR can contribute to decision support efforts relevant to commercial fisheries through the improvement of the understanding of environmental conditions relative to Tuna. The critically endangered Atlantic Bluefin Tuna (Thunnus thynnus)

Otolith chemistry discriminates natal signatures of yellowfin tuna (Thunnus albacares) in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Kitchens, L. L.; Rooker, J. R.

2016-02-01

In this study, the otolith chemistry of young-of-the-year (YOY) yellowfin tuna (Thunnus albacares) was examined to determine whether chemical signatures are distinct across different putative spawning areas in the Atlantic Ocean. Yellowfin tuna is a highly migratory species that is currently managed as a single panmictic stock in the Atlantic Ocean; however, uncertainty remains regarding the population structure of yellowfin in this region, particularly concerning the degree of mixing between spawning populations. Analysis of naturally occurring chemical tracers in otoliths provides a valuable means to reconstruct a fish's environmental history and is thus a promising approach for delineating stock structure of Atlantic yellowfin tuna. YOY yellowfin tuna otoliths were collected from 5 locations in the Atlantic Ocean (Gulf of Mexico, SE Caribbean, Brazil, Cape Verde, and Gulf of Guinea) from 2013-2015 and trace element (Li, Mg, Mn, Co, Cu, Sr, Zn, and Ba) and stable isotope (δ13C and δ18O) analyses were conducted to investigate regional variation in otolith chemical composition. Results show significant differences among nursery areas in both trace element (MANOVA, p<0.001) and δ13C and δ18O signatures (ANOVA, p=0.017 and p=0.001, respectively). Particularly high spatial separation was observed based on eastern Atlantic (Gulf of Guinea + Cape Verde) and western Atlantic (Gulf of Mexico + Brazil + Martinique) nursery areas, indicating the approach has promise for distinguishing migrants displaying trans-ocean movement. These chemical signatures will be used to assign adult yellowfin tuna to their nursery of origin, ultimately providing an improved understanding of the stock structure and movement of yellowfin tuna in the Atlantic Ocean.

Organohalogen concentrations and feeding status in Atlantic salmon (Salmo salar L.) of the Baltic Sea during the spawning run.

PubMed

Vuorinen, Pekka J; Kiviranta, Hannu; Koistinen, Jaana; Pöyhönen, Outi; Ikonen, Erkki; Keinänen, Marja

2014-01-15

Changes in the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Baltic salmon muscle were studied during the spawning migration from the southern Baltic Sea to rivers flowing into the northern Gulf of Bothnia and during the spawning period. The aim was to obtain information to facilitate the arrangement of salmon fisheries such that the human dioxin intake is taken into account. The EC maximum allowable total toxic equivalent concentration (WHO-TEQPCDD/F+PCB) was exceeded in the muscle of the majority of the migrating salmon, except in the Baltic Proper. The fresh-weight-based concentrations of all toxicant groups in salmon tended to be the lowest in the Baltic Proper and the Northern Quark, and all toxicant concentrations, except PCDDs and PCDFs, were significantly higher in the spawning salmon than in the salmon caught during the spawning run. The fat content of the salmon muscle decreased by 60% during the spawning run, and the lipid-based total toxicant concentrations were consequently 4.2-6.2 times higher during the spawning period than during the spawning migration. However, the toxicants were concentrated just before spawning, and thus there is no essential difference related to whether the salmon are caught in the sea or the recreational river fishery. © 2013.

Cod Collapse and Climate in the North Atlantic

NASA Astrophysics Data System (ADS)

Oremus, K. L.; Meng, K. C.; Gaines, S.

2016-02-01

Understanding the determinants of fish population dynamics is crucial to the recovery of many fisheries. Current research emphasizes the role of environmental conditions in driving fish populations, but the magnitude of and mechanisms behind these effects on crucial populations are not well established. Despite aggressive management efforts, New England cod fisheries have been in decline for several decades and have now reached unprecedented lows. We find a strong negative relationship between the North Atlantic Oscillation (NAO) and subsequent adult cod biomass and catch. In the Gulf of Maine fishery, a 1-unit NAO increase is associated with a 13% decrease in the biomass of age-1 cod the following year, a decrease that persists as the affected cohort matures. We further detect that a 1-unit NAO increase can lower commercial catch for up to 19 subsequent years, suggesting that fishing practices may be inadvertently exacerbating NAO's direct biological effects. These results imply that 18% and 32% of the overall decline in adult biomass and catch, respectively, since 1980 can be attributed to the NAO's recent multi-decadal positive phase. The Georges Bank cod fishery displays similar patterns. Because there is a delay between an NAO event and subsequent declines in adult biomass, our finding implies that already observed NAO events can be used in stock forecasts, providing lead time for adaptive policy. More broadly, our approach can inform forecasting efforts for other fisheries strongly affected by natural and anthropogenic climatic variation.

Constant proportion harvest policies: dynamic implications in the Pacific halibut and Atlantic cod fisheries.

PubMed

Yakubu, Abdul-Aziz; Li, Nianpeng; Conrad, Jon M; Zeeman, Mary-Lou

2011-07-01

Overfishing, pollution and other environmental factors have greatly reduced commercially valuable stocks of fish. In a 2006 Science article, a group of ecologists and economists warned that the world may run out of seafood from natural stocks if overfishing continues at current rates. In this paper, we explore the interaction between a constant proportion harvest policy and recruitment dynamics. We examine the discrete-time constant proportion harvest policy discussed in Ang et al. (2009) and then expand the framework to include stock-recruitment functions that are compensatory and overcompensatory, both with and without the Allee effect. We focus on constant proportion policies (CPPs). CPPs have the potential to stabilize complex overcompensatory stock dynamics, with or without the Allee effect, provided the rates of harvest stay below a threshold. If that threshold is exceeded, CPPs are known to result in the sudden collapse of a fish stock when stock recruitment exhibits the Allee effect. In case studies, we analyze CPPs as they might be applied to Gulf of Alaska Pacific halibut fishery and the Georges Bank Atlantic cod fishery based on harvest rates from 1975 to 2007. The best fit models suggest that, under high fishing mortalities, the halibut fishery is vulnerable to sudden population collapse while the cod fishery is vulnerable to steady decline to zero. The models also suggest that CPP with mean harvesting levels from the last 30 years can be effective at preventing collapse in the halibut fishery, but these same policies would lead to steady decline to zero in the Atlantic cod fishery. We observe that the likelihood of collapse in both fisheries increases with increased stochasticity (for example, weather variability) as predicted by models of global climate change. Copyright © 2011 Elsevier Inc. All rights reserved.

Cardiovascular and haematological responses of Atlantic cod (Gadus morhua) to acute temperature increase.

PubMed

Gollock, M J; Currie, S; Petersen, L H; Gamperl, A K

2006-08-01

For fish to survive large acute temperature increases (i.e. >10.0 degrees C) that may bring them close to their critical thermal maximum (CTM), oxygen uptake at the gills and distribution by the cardiovascular system must increase to match tissue oxygen demand. To examine the effects of an acute temperature increase ( approximately 1.7 degrees C h(-1) to CTM) on the cardiorespiratory physiology of Atlantic cod, we (1) carried out respirometry on 10.0 degrees C acclimated fish, while simultaneously measuring in vivo cardiac parameters using Transonic probes, and (2) constructed in vitro oxygen binding curves on whole blood from 7.0 degrees C acclimated cod at a range of temperatures. Both cardiac output (Q) and heart rate (fh) increased until near the fish's CTM (22.2+/-0.2 degrees C), and then declined rapidly. Q(10) values for Q and fh were 2.48 and 2.12, respectively, and increases in both parameters were tightly correlated with O(2) consumption. The haemoglobin (Hb)-oxygen binding curve at 24.0 degrees C showed pronounced downward and rightward shifts compared to 20.0 degrees C and 7.0 degrees C, indicating that both binding capacity and affinity decreased. Further, Hb levels were lower at 24.0 degrees C than at 20.0 degrees C and 7.0 degrees C. This was likely to be due to cell swelling, as electrophoresis of Hb samples did not suggest protein denaturation, and at 24.0 degrees C Hb samples showed peak absorbance at the expected wavelength (540 nm). Our results show that cardiac function is unlikely to limit metabolic rate in Atlantic cod from Newfoundland until close to their CTM, and we suggest that decreased blood oxygen binding capacity may contribute to the plateau in oxygen consumption.

The Relationship Between Acoustic Target Strength and Body Length for Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus)

DTIC Science & Technology

2010-10-01

sturgeon feeding portray them as opportunistic benthivores, feeding primar- ily on mollusks, polychaete worms, amphipods, isopods, shrimp and small bottom...dwelling fishes and insect larvae (Gilbert 1989; Smith 1985). The Atlantic sturgeon is anadromous, entering freshwater rivers to spawn at water...bottom (small rubble, gravel, hard clay, and limestone) is required for successful egg attachment and incubation, while also protecting larvae from

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grimes, B.H.; Huish, M.T.; Kerby, J.H.

1989-08-01

Species profiles are literature summaries of the taxonomy, morphology, range, life history, and environmental requirements of coastal species. They are designed to assist in environmental impact assessments. The summer flounder supports an important commercial and recreational fishery in the Mid-Atlantic and are important constituent of estuarine and continental shelf systems throughout the region. Summer flounder spawning begins in September and winter flounder spawning begins in June. Summer flounder eggs are pelagic whereas winter flounder eggs are demersal. Summer flounder larvae are more abundant in inlets, and juveniles are found in estuarine seagrass beds in salinities {>=}12 ppt. Winter flounder juvenilesmore » are abundant in shallow bays and estuaries, moving seaward in spring and summer. Growth of winter flounder and summer flounder is seasonal. There are probably three spawning populations of both species which produce a complex stock pattern. Summer flounder are tolerant of a wide range of chemical and physica faactors, but prefer {gt}10 ppt salinities. Winter flounder optimal temperature is 18.5 {degree}C. Diseases of winter flounder are more prevalent in polluted waters. Summer flounder are tolerant of sediments laden with contaminants. 64 refs., 5 figs., 2 tabs.« less

Inventory of Selected Freshwater-Ecology Studies From the New England Coastal Basins (Maine, New Hampshire, Massachusetts, Rhode Island), 1937-1997

DTIC Science & Technology

1999-01-01

plains. The Atlantic Coastal Pine Barrens ecoregion is represented in the southeastern part of the study unit and includes Cape Cod and the islands...Providence, Washington 1The area of the NECB study unit within the Atlantic Coastal Pine Barrens ecoregion had previously been part of the Northeastern...Unit are the Northeastern Highlands, Northeastern Coastal Zone, and Atlantic Coastal Pine Barrens1 (U.S. Environ- mental Protection Agency-National

Skeletal muscle growth dynamics and the influence of first-feeding diet in Atlantic cod larvae (Gadus morhua L.)

PubMed Central

Vo, Tu A.; Galloway, Trina F.; Bardal, Tora; Halseth, Christine K.; Øie, Gunvor

2016-01-01

ABSTRACT Dynamics between hypertrophy (increase in cell size) and hyperplasia (increase in cell numbers) of white and red muscle in relation to body size [standard length (SL)], and the influence of the first-feeding diets on muscle growth were investigated in Atlantic cod larvae (Gadus morhua). Cod larvae were fed copepod nauplii or rotifers of different nutritional qualities from 4 to 29 days post hatching (dph), Artemia nauplii from 20 to 40 dph and a formulated diet from 36 to 60 dph. The short period of feeding with cultivated copepod nauplii had a positive effect on both muscle hyperplasia and hypertrophy after the copepod/rotifer phase (19 dph), and a positive long term effect on muscle hypertrophy (60 dph). The different nutritional qualities of rotifers did not significantly affect muscle growth. We suggest here a model of the dynamics between hyperplasia and hypertrophy of red and white muscle fibre cells in relation to cod SL (4 to 30 mm), where the different red and white muscle growth phases clearly coincided with different metamorphosis stages in cod larvae. These shifts could be included as biomarkers for the different stages of development during metamorphosis. The main dietary muscle effect was that hypertrophic growth of red muscle fibres was stronger in cod larvae that were fed copepods than in larvae that were fed rotifers, both in relation to larval age and size. Red muscle fibres are directly involved in larval locomotory performance, but may also play an important role in the larval myogenesis. This can have a long term effect on growth potential and fish performance. PMID:27612513

Spawning of Bluefin Tuna in the Black Sea: Historical Evidence, Environmental Constraints and Population Plasticity

PubMed Central

MacKenzie, Brian R.; Mariani, Patrizio

2012-01-01

The lucrative and highly migratory Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758; Scombridae), used to be distributed widely throughout the north Atlantic Ocean, Mediterranean Sea and Black Sea. Its migrations have supported sustainable fisheries and impacted local cultures since antiquity, but its biogeographic range has contracted since the 1950s. Most recently, the species disappeared from the Black Sea in the late 1980s and has not yet recovered. Reasons for the Black Sea disappearance, and the species-wide range contraction, are unclear. However bluefin tuna formerly foraged and possibly spawned in the Black Sea. Loss of a locally-reproducing population would represent a decline in population richness, and an increase in species vulnerability to perturbations such as exploitation and environmental change. Here we identify the main genetic and phenotypic adaptations that the population must have (had) in order to reproduce successfully in the specific hydrographic (estuarine) conditions of the Black Sea. By comparing hydrographic conditions in spawning areas of the three species of bluefin tunas, and applying a mechanistic model of egg buoyancy and sinking rate, we show that reproduction in the Black Sea must have required specific adaptations of egg buoyancy, fertilisation and development for reproductive success. Such adaptations by local populations of marine fish species spawning in estuarine areas are common as is evident from a meta-analysis of egg buoyancy data from 16 species of fish. We conclude that these adaptations would have been necessary for successful local reproduction by bluefin tuna in the Black Sea, and that a locally-adapted reproducing population may have disappeared. Recovery of bluefin tuna in the Black Sea, either for spawning or foraging, will occur fastest if any remaining locally adapted individuals are allowed to survive, and by conservation and recovery of depleted Mediterranean populations which could through time re-establish local Black Sea spawning and foraging. PMID:22848367

Trophic structure of the Barents Sea fish assemblage with special reference to the cod stock recoverability

NASA Astrophysics Data System (ADS)

Dolgov, Andrey V.

2009-04-01

The species composition and trophic structure of the Barents Sea fish assemblage is analysed based on data from research survey trawls and diet analyses of various species. Atlantic cod was the dominant fish species encountered, accounting for more than 55% by abundance or biomass. Only five fish species (long rough dab, thorny skate, Greenland halibut, deepwater redfish and saithe) were sufficiently abundant to be considered as possible food competitors with cod in the Barents Sea. However, possible trophic competition is not high, due to low spatial and temporal overlap between cod and these other species. Analyses of fish assemblages and trophic structures of the Barents Sea and other areas (North Sea, Western Greenland, Newfoundland-Labrador shelf) suggest that Barents Sea cod is the only cod stock for which the ability to recover may not be restricted by trophic relations among fishes, due to a lack of other abundant predatory species and low potential for competition caused by spatial-temporal changes.

Variation in organic matter and water color in Lake Mälaren during the past 70 years.

PubMed

Johansson, L; Temnerud, J; Abrahamsson, J; Berggren Kleja, D

2010-03-01

Interest in long time series of organic matter data has recently increased due to concerns about the effects of global climate change on aquatic ecosystems. This study presents and evaluates unique time series of chemical oxygen demand (COD) and water color from Lake Malaren, Sweden, stretching almost seven decades (1935-2004). A negative linear trend was found in COD, but not in water color. The decrease was mainly due to installation of sewage works around 1970. Time series of COD and water color had cyclic pattern. It was strongest for COD, with 23 years periodicity. Similar periodicity observed in air temperature and precipitation in Sweden has been attributed to the North Atlantic Oscillation index and solar system orbit, suggesting that COD in Lake Mälaren is partly derived from algae. Discharge influenced water color more than COD, possibly because water color consists of colored substances brought into the lake from surrounding soils.

Characterizing and predicting the distribution of Baltic Sea flounder (Platichthys flesus) during the spawning season

NASA Astrophysics Data System (ADS)

Orio, Alessandro; Bergström, Ulf; Casini, Michele; Erlandsson, Mårten; Eschbaum, Redik; Hüssy, Karin; Lehmann, Andreas; Ložys, Linas; Ustups, Didzis; Florin, Ann-Britt

2017-08-01

Identification of essential fish habitats (EFH), such as spawning habitats, is important for nature conservation, sustainable fisheries management and marine spatial planning. Two sympatric flounder (Platichthys flesus) ecotypes are present in the Baltic Sea, pelagic and demersal spawning flounder, both displaying ecological and physiological adaptations to the low-salinity environment of this young inland sea. In this study we have addressed three main research questions: 1) What environmental conditions characterize the spatial distribution and abundance of adult flounder during the spawning season? 2) What are the main factors defining the habitats of the two flounder ecotypes during the spawning season? 3) Where are the potential spawning areas of flounder? We modelled catch per unit of effort (CPUE) of flounder from gillnet surveys conducted over the southern and central Baltic Sea in the spring of 2014 and 2015 using generalized additive models. A general model included all the stations fished during the survey while two other models, one for the demersal and one for the pelagic spawning flounder, included only the stations where each flounder ecotype should dominate. The general model captured distinct ecotype-specific signals as it identified dual salinity and water depth responses. The model for the demersal spawning flounder revealed a negative relation with the abundance of round goby (Neogobius melanostomus) and a positive relation with Secchi depth and cod abundance. Vegetation and substrate did not play an important role in the choice of habitat for the demersal ecotype. The model for the pelagic spawning flounder showed a negative relation with temperature and bottom current and a positive relation with salinity. Spatial predictions of potential spawning areas of flounder showed a decrease in habitat availability for the pelagic spawning flounder over the last 20 years in the central part of the Baltic Sea, which may explain part of the observed changes in populations' biomass. We conclude that spatiotemporal modelling of habitat availability can improve our understanding of fish stock dynamics and may provide necessary biological knowledge for the development of marine spatial plans.

Energy profiling of demersal fish: a case-study in wind farm artificial reefs.

PubMed

De Troch, Marleen; Reubens, Jan T; Heirman, Elke; Degraer, Steven; Vincx, Magda

2013-12-01

The construction of wind farms introduces artificial hard substrates in sandy sediments. As Atlantic cod (Gadus morhua) and pouting (Trisopterus luscus) tend to aggregate in order to feed around these reefs, energy profiling and trophic markers were applied to study their feeding ecology in a wind farm in the Belgian part of the North Sea. The proximate composition (carbohydrates, proteins and lipids) differed significantly between liver and muscle tissue but not between fish species or between their potential prey species. Atlantic cod showed to consume more energy than pouting. The latter had a higher overall energy reserve and can theoretically survive twice as long on the available energy than cod. In autumn, both fish species could survive longer on their energy than in spring. Polyunsaturated fatty acids were found in high concentrations in fish liver. The prey species Jassa and Pisidia were both rich in EPA while Jassa had a higher DHA content than Pisidia. Energy profiling supported the statement that wind farm artificial reefs are suitable feeding ground for both fish species. Sufficient energy levels were recorded and there is no indication of competition.

A sampler for capturing larval and juvenile Atlantic menhaden

USGS Publications Warehouse

Hedrick, J.D.; Hedrick, L.R.; Margraf, F.J.

2005-01-01

Interest in capturing larval and juvenile Atlantic menhaden Brevoortia tyrannus for use in laboratory studies required the design and construction of a sampling device that would allow us to make collections of live fish from open-water areas. Our device for capturing 1-2.5-in larval-juvenile fish was constructed of a stainless steel frame that supported a 9.84-ft-long (3-m-long)5 cone plankton net with a 3.28-ft-diameter (1-m-diameter) opening and a 0.04-in (1-mm) mesh size. Although the plankton net was similar to that used during typical larval fish collections, the cod end was constructed of Plexiglas and was nearly watertight; this prevented impingement and injury to larval fish and provided a calm-water environment. The cod end was designed for quick release from the plankton net, and the entire cod end could be submerged into a 75-gal onboard holding tank. This design and technique obviated the netting or emerging of fish from the water until they were returned to the laboratory. ?? Copyright by the American Fisheries Society 2005.

Size-dependent social attraction and repulsion explains the decision of Atlantic cod Gadus morhua to enter baited pots.

PubMed

Anders, N; Fernö, A; Humborstad, O-B; Løkkeborg, S; Rieucau, G; Utne-Palm, A C

2017-12-01

The present study tested whether the presence of already retained fishes inside baited fish pots acted as a social attraction and affected the entrance probability of Atlantic cod Gadus morhua in a fjord in northern Norway. Video analysis revealed that the probability of an entrance initially increased with the presence of low numbers of fishes inside the pot, but subsequently decreased at a critical number of caught fishes. The critical number was dependent on the size of the G. morhua attempting to enter. This demonstrates that social attraction and repulsion play a role in G. morhua pot fishing and has important implications for the capture efficiency of fisheries executed with pots. © 2017 The Fisheries Society of the British Isles.

Spatial scale, means and gradients of hydrographic variables define pelagic seascapes of bluefin and bullet tuna spawning distribution.

PubMed

Alvarez-Berastegui, Diego; Ciannelli, Lorenzo; Aparicio-Gonzalez, Alberto; Reglero, Patricia; Hidalgo, Manuel; López-Jurado, Jose Luis; Tintoré, Joaquín; Alemany, Francisco

2014-01-01

Seascape ecology is an emerging discipline focused on understanding how features of the marine habitat influence the spatial distribution of marine species. However, there is still a gap in the development of concepts and techniques for its application in the marine pelagic realm, where there are no clear boundaries delimitating habitats. Here we demonstrate that pelagic seascape metrics defined as a combination of hydrographic variables and their spatial gradients calculated at an appropriate spatial scale, improve our ability to model pelagic fish distribution. We apply the analysis to study the spawning locations of two tuna species: Atlantic bluefin and bullet tuna. These two species represent a gradient in life history strategies. Bluefin tuna has a large body size and is a long-distant migrant, while bullet tuna has a small body size and lives year-round in coastal waters within the Mediterranean Sea. The results show that the models performance incorporating the proposed seascape metrics increases significantly when compared with models that do not consider these metrics. This improvement is more important for Atlantic bluefin, whose spawning ecology is dependent on the local oceanographic scenario, than it is for bullet tuna, which is less influenced by the hydrographic conditions. Our study advances our understanding of how species perceive their habitat and confirms that the spatial scale at which the seascape metrics provide information is related to the spawning ecology and life history strategy of each species.

Temporal patterns of migration and spawning of river herring in coastal Massachusetts

USGS Publications Warehouse

Rosset, Julianne; Roy, Allison; Gahagan, Benjamin I.; Whiteley, Andrew R.; Armstrong, Michael P.; Sheppard, John J.; Jordaan, Adrian

2017-01-01

Migrations of springtime Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis, collectively referred to as river herring, are monitored in many rivers along the Atlantic coast to estimate population sizes. While these estimates give an indication of annual differences in the number of returning adults, links to the subsequent timing and duration of spawning and freshwater juvenile productivity remain equivocal. In this study, we captured juvenile river herring at night in 20 coastal Massachusetts lakes using a purse seine and extracted otoliths to derive daily fish ages and back-calculate spawn dates. Estimates of spawning dates were compared with fishway counts of migrating adults to assess differences in migration timing and the timing and duration of spawning. We observed a distinct delay between the beginning of the adult migration run and the start of spawning, ranging from 7 to 28 d across the 20 lakes. Spawning continued 13–48 d after adults stopped migrating into freshwater, further demonstrating a pronounced delay in spawning following migration. Across the study sites the duration of spawning (43–76 d) was longer but not related to the duration of migration (29–66 d). The extended spawning period is consistent with recent studies suggesting that Alewives are indeterminate spawners. The long duration in freshwater provides the opportunity for top-down (i.e., predation on zooplankton) and bottom-up (i.e., food for avian, fish, and other predators) effects, with implications for freshwater food webs and nutrient cycling. General patterns of spawn timing and duration can be incorporated into population models and used to estimate temporal changes in productivity associated with variable timing and density of spawning river herring in lakes.

[New view on the population genetic structure of marine fish].

PubMed

Salmenkova, E A

2011-11-01

The view on homogeneous population genetic structure in many marine fish with high mobility has changed significantly during the last ten years. Molecular genetic population studies over the whole ranges of such species as Atlantic herring and Atlantic cod showed a complex picture of spatial differentiation both on the macrogeographic and, in many areas, on the microgeographic scale, although the differentiation for neutral molecular markers was low. It was established that the migration activity of such fish is constrained in many areas of the species range by hydrological and physicochemical transition zones (environmental gradients), as well as gyres in the spawning regions. Natal homing was recorded in a number of marine fish species. Existing in marine fish constraints of gene migration and a very high variance of reproductive success determine a significantly smaller proportion of effective reproductive size of their populations in the total population size, which generates more complex abundance dynamics than assumed earlier. The various constraints on gene migration and natal homing in marine fish promote the formation of local adaptations at ecologically important phenotypic traits. Effects of selection underlying adaptations are actively investigated in marine fish on the genomic level, using approaches of population genomics. The knowledge of adaptive intraspecific structure enables understanding the ecological and evolutionary processes, that influence biodiversity and providing spatial frames for conservation of genetic resources under commercial exploitation. Contemporary views on the population genetic and adaptive structures or biocomplexity in marine fish support and develop the main principles of the conception of systemic organization of the species and its regional populations, which were advanced by Yu.P. Altukhov and Yu.G. Rychkov.

Discrimination between weaned and unweaned Atlantic cod (Gadus morhua) in capture-based aquaculture (CBA) by X-ray imaging and radio-frequency metal detector.

PubMed

Misimi, Ekrem; Martinsen, Svein; Mathiassen, John Reidar; Erikson, Ulf

2014-01-01

The aim of this study was to investigate the feasibility of two detection methods for use in discrimination and sorting of adult Atlantic cod (about 2 kg) in the small scale capture-based aquaculture (CBA). Presently, there is no established method for discrimination of weaned and unweaned cod in CBA. Generally, 60-70% of the wild-caught cod in the CBA are weaned into commercial dry feed. To increase profitability for the fish farmers, unweaned cod must be separated from the stock, meaning the fish must be sorted into two groups - unweaned and weaned from moist feed. The challenges with handling of large numbers of fish in cages, defined the limits of the applied technology. As a result, a working model was established, focusing on implementing different marking materials added to the fish feed, and different technology for detecting the feed presence in the fish gut. X-ray imaging in two modes (planar and dual energy band) and sensitive radio-frequency metal detection were the detection methods that were chosen for the investigations. Both methods were tested in laboratory conditions using dead fish with marked feed inserted into the gut cavity. In particular, the sensitive radio-frequency metal detection method with carbonyl powder showed very promising results in detection of marked feed. Results show also that Dual energy band X-ray imaging may have potential for prediction of fat content in the feed. Based on the investigations it can be concluded that both X-ray imaging and sensitive radio-frequency metal detector technology have the potential for detecting cod having consumed marked feed. These are all technologies that may be adapted to large scale handling of fish from fish cages. Thus, it may be possible to discriminate between unweaned and weaned cod in a large scale grading situation. Based on the results of this study, a suggestion for evaluation of concept for in-situ sorting system is presented.

Benzocaine as a fish anesthetic: efficacy and safety for spawning-phase salmon

USGS Publications Warehouse

Gilderhus, P.A.

1990-01-01

The anesthetic benzocaine was tested for efficacy and safety for spawning-phase chinook salmon (Oncorhynchus tshawytscha) and Atlantic salmon (Salmo salar) at federal fish hatcheries. Tests were conducted in the existing hatchery water supplies (soft water; temperatures, 10–13 °C. Crystalline benzocaine was dissolved in ethanol (1 g/30 mL), and aliquots of that stock solution were added to the water in test tanks. Benzocaine concentrations of 25–30 mg/L anesthetized most fish in less than 3.5 min, and most fish recovered in less than 10 min after 15 min of exposure. Safety margins were narrow; both species tolerated 30 mg/L for about 20 min, but 25 min of exposure caused deaths. For 15 min exposures, concentrations of 35 mg/L for chinook salmon and 40 mg/L for Atlantic salmon were lethal.

Timing and locations of reef fish spawning off the southeastern United States

PubMed Central

Heyman, William D.; Karnauskas, Mandy; Kobara, Shinichi; Smart, Tracey I.; Ballenger, Joseph C.; Reichert, Marcel J. M.; Wyanski, David M.; Tishler, Michelle S.; Lindeman, Kenyon C.; Lowerre-Barbieri, Susan K.; Switzer, Theodore S.; Solomon, Justin J.; McCain, Kyle; Marhefka, Mark; Sedberry, George R.

2017-01-01

Managed reef fish in the Atlantic Ocean of the southeastern United States (SEUS) support a multi-billion dollar industry. There is a broad interest in locating and protecting spawning fish from harvest, to enhance productivity and reduce the potential for overfishing. We assessed spatiotemporal cues for spawning for six species from four reef fish families, using data on individual spawning condition collected by over three decades of regional fishery-independent reef fish surveys, combined with a series of predictors derived from bathymetric features. We quantified the size of spawning areas used by reef fish across many years and identified several multispecies spawning locations. We quantitatively identified cues for peak spawning and generated predictive maps for Gray Triggerfish (Balistes capriscus), White Grunt (Haemulon plumierii), Red Snapper (Lutjanus campechanus), Vermilion Snapper (Rhomboplites aurorubens), Black Sea Bass (Centropristis striata), and Scamp (Mycteroperca phenax). For example, Red Snapper peak spawning was predicted in 24.7–29.0°C water prior to the new moon at locations with high curvature in the 24–30 m depth range off northeast Florida during June and July. External validation using scientific and fishery-dependent data collections strongly supported the predictive utility of our models. We identified locations where reconfiguration or expansion of existing marine protected areas would protect spawning reef fish. We recommend increased sampling off southern Florida (south of 27° N), during winter months, and in high-relief, high current habitats to improve our understanding of timing and location of reef fish spawning off the southeastern United States. PMID:28264006

Comment on “Slow adaptation in the face of rapid warming leads to collapse of the Gulf of Maine cod fishery”

NASA Astrophysics Data System (ADS)

Palmer, Michael C.; Deroba, Jonathan J.; Legault, Christopher M.; Brooks, Elizabeth N.

2016-04-01

Pershing et al. (Reports, 13 November, p. 809) concluded that failure to account for temperature in the assessment and management of Gulf of Maine Atlantic cod caused overfishing. We argue that the “extra mortality” calculation driving this conclusion is an artifact. Environmental factors affect all stocks, but attribution of additional mortality to temperature alone by Pershing et al. is unsupported by the data.

Diet affects the redox system in developing Atlantic cod (Gadus morhua) larvae.

PubMed

Penglase, Samuel; Edvardsen, Rolf B; Furmanek, Tomasz; Rønnestad, Ivar; Karlsen, Ørjan; van der Meeren, Terje; Hamre, Kristin

2015-08-01

The growth and development of marine fish larvae fed copepods is superior to those fed rotifers, but the underlying molecular reasons for this are unclear. In the following study we compared the effects of such diets on redox regulation pathways during development of Atlantic cod (Gadus morhua) larvae. Cod larvae were fed a control diet of copepods or the typical rotifer/Artemia diet commonly used in commercial marine fish hatcheries, from first feeding until after metamorphosis. The oxidised and reduced glutathione levels, the redox potential, and the mRNA expression of 100 genes in redox system pathways were then compared between treatments during larval development. We found that rotifer/Artemia-fed cod larvae had lower levels of oxidised glutathione, a more reduced redox potential, and altered expression of approximately half of the redox system genes when compared to copepod-fed larvae. This rotifer/Artemia diet-induced differential regulation of the redox system was greatest during periods of suboptimal growth. Upregulation of the oxidative stress response transcription factor, nrf2, and NRF2 target genes in rotifer/Artemia fed larvae suggest this diet induced an NRF2-mediated oxidative stress response. Overall, the data demonstrate that nutritional intake plays a role in regulating the redox system in developing fish larvae. This may be a factor in dietary-induced differences observed in larval growth. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Lobster and cod benefit from small-scale northern marine protected areas: inference from an empirical before–after control-impact study

PubMed Central

Moland, Even; Olsen, Esben Moland; Knutsen, Halvor; Garrigou, Pauline; Espeland, Sigurd Heiberg; Kleiven, Alf Ring; André, Carl; Knutsen, Jan Atle

2013-01-01

Marine protected areas (MPAs) are increasingly implemented as tools to conserve and manage fisheries and target species. Because there are opportunity costs to conservation, there is a need for science-based assessment of MPAs. Here, we present one of the northernmost documentations of MPA effects to date, demonstrated by a replicated before–after control-impact (BACI) approach. In 2006, MPAs were implemented along the Norwegian Skagerrak coast offering complete protection to shellfish and partial protection to fish. By 2010, European lobster (Homarus gammarus) catch-per-unit-effort (CPUE) had increased by 245 per cent in MPAs, whereas CPUE in control areas had increased by 87 per cent. Mean size of lobsters increased by 13 per cent in MPAs, whereas increase in control areas was negligible. Furthermore, MPA-responses and population development in control areas varied significantly among regions. This illustrates the importance of a replicated BACI design for reaching robust conclusions and management decisions. Partial protection of Atlantic cod (Gadus morhua) was followed by an increase in population density and body size compared with control areas. By 2010, MPA cod were on average 5 cm longer than in any of the control areas. MPAs can be useful management tools in rebuilding and conserving portions of depleted lobster populations in northern temperate waters, and even for a mobile temperate fish species such as the Atlantic cod. PMID:23303544

Forecasting the major influences of predation and environment on cod recovery in the northern Gulf of St. Lawrence.

PubMed

Bousquet, Nicolas; Chassot, Emmanuel; Duplisea, Daniel E; Hammill, Mike O

2014-01-01

The northern Gulf of St. Lawrence (NGSL) stock of Atlantic cod (Gadus morhua), historically the second largest cod population in the Western Atlantic, has known a severe collapse during the early 1990 s and is currently considered as endangered by the Committee on the Status of Endangered Wildlife in Canada. As for many fish populations over the world which are currently being heavily exploited or overfished, urgent management actions in the form of recovery plans are needed for restoring this stock to sustainable levels. Stochastic projections based on a statistical population model incorporating predation were conducted over a period of 30 years (2010-2040) to assess the expected outcomes of alternative fishing strategies on the stock recovery under different scenarios of harp seal (Pagophilus groenlandicus) abundance and environmental conditions. This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock. Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status. Under current or warmer conditions in the Gulf of St. Lawrence, partial recovery might only be achieved by significant reductions in both fishing and predation pressure. In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry.

Forecasting the Major Influences of Predation and Environment on Cod Recovery in the Northern Gulf of St. Lawrence

PubMed Central

Bousquet, Nicolas; Chassot, Emmanuel; Duplisea, Daniel E.; Hammill, Mike O.

2014-01-01

The northern Gulf of St. Lawrence (NGSL) stock of Atlantic cod (Gadus morhua), historically the second largest cod population in the Western Atlantic, has known a severe collapse during the early 1990 s and is currently considered as endangered by the Committee on the Status of Endangered Wildlife in Canada. As for many fish populations over the world which are currently being heavily exploited or overfished, urgent management actions in the form of recovery plans are needed for restoring this stock to sustainable levels. Stochastic projections based on a statistical population model incorporating predation were conducted over a period of 30 years (2010–2040) to assess the expected outcomes of alternative fishing strategies on the stock recovery under different scenarios of harp seal (Pagophilus groenlandicus) abundance and environmental conditions. This sensitivity study shows that water temperature is key in the rebuilding of the NGSL cod stock. Model projections suggest that maintaining the current management practice under cooler water temperatures is likely to maintain the species in an endangered status. Under current or warmer conditions in the Gulf of St. Lawrence, partial recovery might only be achieved by significant reductions in both fishing and predation pressure. In the medium-term, a management strategy that reduces catch could be favoured over a complete moratorium so as to minimize socio-economic impacts on the industry. PMID:24523852

Spawning habitat selection of hickory shad

USGS Publications Warehouse

Harris, Julianne E.; Hightower, J.E.

2011-01-01

We examined the spawning habitat selectivity of hickory shad Alosa mediocris, an anadromous species on the Atlantic coast of North America. Using plankton tows and artificial substrates (spawning pads), we collected hickory shad eggs in the Roanoke River, North Carolina, to identify spawning timing, temperature, and microhabitat use. Hickory shad eggs were collected by both sampling gears in March and April. The results from this and three other studies in North Carolina indicate that spawning peaks at water temperatures between 12.0??C and 14.9??C and that approximately 90% occurs between 11.0??C and 18.9??C. Hickory shad eggs were collected in run and riffle habitats. Water velocity and substrate were significantly different at spawning pads with eggs than at those without eggs, suggesting that these are important microhabitat factors for spawning. Hickory shad eggs were usually collected in velocities of at least 0.1 m/s and on all substrates except those dominated by silt. Eggs were most abundant on gravel, cobble, and boulder substrates. Hickory shad spawned further upstream in years when water discharge rates at Roanoke Rapids were approximately average during March and April (2005 and 2007), as compared with a severe drought year (2006), suggesting that water flows may affect not only spawning site selection but also the quantity and quality of spawning habitat available at a macrohabitat scale. Using our field data and a Bayesian approach to resource selection analysis, we developed a preliminary habitat suitability model for hickory shad. This Bayesian approach provides an objective framework for updating the model as future studies of hickory shad spawning habitat are conducted. ?? American Fisheries Society 2011.

Multiple-locus, variable number of tandem repeat analysis (MLVA) of the fish-pathogen Francisella noatunensis

PubMed Central

2011-01-01

Background Since Francisella noatunensis was first isolated from cultured Atlantic cod in 2004, it has emerged as a global fish pathogen causing disease in both warm and cold water species. Outbreaks of francisellosis occur in several important cultured fish species making a correct management of this disease a matter of major importance. Currently there are no vaccines or treatments available. A strain typing system for use in studies of F. noatunensis epizootics would be an important tool for disease management. However, the high genetic similarity within the Francisella spp. makes strain typing difficult, but such typing of the related human pathogen Francisella tullarensis has been performed successfully by targeting loci with higher genetic variation than the traditional signature sequences. These loci are known as Variable Numbers of Tandem Repeat (VNTR). The aim of this study is to identify possible useful VNTRs in the genome of F. noatunensis. Results Seven polymorphic VNTR loci were identified in the preliminary genome sequence of F. noatunensis ssp. noatunensis GM2212 isolate. These VNTR-loci were sequenced in F. noatunensis isolates collected from Atlantic cod (Gadus morhua) from Norway (n = 21), Three-line grunt (Parapristipoma trilineatum) from Japan (n = 1), Tilapia (Oreochromis spp.) from Indonesia (n = 3) and Atlantic salmon (Salmo salar) from Chile (n = 1). The Norwegian isolates presented in this study show both nine allelic profiles and clades, and that the majority of the farmed isolates belong in two clades only, while the allelic profiles from wild cod are unique. Conclusions VNTRs can be used to separate isolates belonging to both subspecies of F. noatunensis. Low allelic diversity in F. noatunensis isolates from outbreaks in cod culture compared to isolates wild cod, indicate that transmission of these isolates may be a result of human activity. The sequence based MLVA system presented in this study should provide a good starting point for further development of a genotyping system that can be used in studies of epizootics and disease management of francisellosis. PMID:21261955

Norway

Atmospheric Science Data Center

2013-04-17

... of the North Sea region. Fishing remains one of the most important occupations in coastal Norway. Gadus morhua (Atlantic Cod) and ... NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed ...

Ancient DNA reveals the Arctic origin of Viking Age cod from Haithabu, Germany

PubMed Central

Star, Bastiaan; Boessenkool, Sanne; Gondek, Agata T.; Nikulina, Elena A.; Hufthammer, Anne Karin; Pampoulie, Christophe; Knutsen, Halvor; André, Carl; Nistelberger, Heidi M.; Dierking, Jan; Petereit, Christoph; Heinrich, Dirk; Jakobsen, Kjetill S.; Stenseth, Nils Chr.; Jentoft, Sissel

2017-01-01

Knowledge of the range and chronology of historic trade and long-distance transport of natural resources is essential for determining the impacts of past human activities on marine environments. However, the specific biological sources of imported fauna are often difficult to identify, in particular if species have a wide spatial distribution and lack clear osteological or isotopic differentiation between populations. Here, we report that ancient fish-bone remains, despite being porous, brittle, and light, provide an excellent source of endogenous DNA (15–46%) of sufficient quality for whole-genome reconstruction. By comparing ancient sequence data to that of modern specimens, we determine the biological origin of 15 Viking Age (800–1066 CE) and subsequent medieval (1066–1280 CE) Atlantic cod (Gadus morhua) specimens from excavation sites in Germany, Norway, and the United Kingdom. Archaeological context indicates that one of these sites was a fishing settlement for the procurement of local catches, whereas the other localities were centers of trade. Fish from the trade sites show a mixed ancestry and are statistically differentiated from local fish populations. Moreover, Viking Age samples from Haithabu, Germany, are traced back to the North East Arctic Atlantic cod population that has supported the Lofoten fisheries of Norway for centuries. Our results resolve a long-standing controversial hypothesis and indicate that the marine resources of the North Atlantic Ocean were used to sustain an international demand for protein as far back as the Viking Age. PMID:28784790

Ancient DNA reveals the Arctic origin of Viking Age cod from Haithabu, Germany.

PubMed

Star, Bastiaan; Boessenkool, Sanne; Gondek, Agata T; Nikulina, Elena A; Hufthammer, Anne Karin; Pampoulie, Christophe; Knutsen, Halvor; André, Carl; Nistelberger, Heidi M; Dierking, Jan; Petereit, Christoph; Heinrich, Dirk; Jakobsen, Kjetill S; Stenseth, Nils Chr; Jentoft, Sissel; Barrett, James H

2017-08-22

Knowledge of the range and chronology of historic trade and long-distance transport of natural resources is essential for determining the impacts of past human activities on marine environments. However, the specific biological sources of imported fauna are often difficult to identify, in particular if species have a wide spatial distribution and lack clear osteological or isotopic differentiation between populations. Here, we report that ancient fish-bone remains, despite being porous, brittle, and light, provide an excellent source of endogenous DNA (15-46%) of sufficient quality for whole-genome reconstruction. By comparing ancient sequence data to that of modern specimens, we determine the biological origin of 15 Viking Age (800-1066 CE) and subsequent medieval (1066-1280 CE) Atlantic cod ( Gadus morhua ) specimens from excavation sites in Germany, Norway, and the United Kingdom. Archaeological context indicates that one of these sites was a fishing settlement for the procurement of local catches, whereas the other localities were centers of trade. Fish from the trade sites show a mixed ancestry and are statistically differentiated from local fish populations. Moreover, Viking Age samples from Haithabu, Germany, are traced back to the North East Arctic Atlantic cod population that has supported the Lofoten fisheries of Norway for centuries. Our results resolve a long-standing controversial hypothesis and indicate that the marine resources of the North Atlantic Ocean were used to sustain an international demand for protein as far back as the Viking Age.

Combined statistical and mechanistic modelling suggests food and temperature effects on survival of early life stages of Northeast Arctic cod (Gadus morhua)

NASA Astrophysics Data System (ADS)

Stige, Leif Chr.; Langangen, Øystein; Yaragina, Natalia A.; Vikebø, Frode B.; Bogstad, Bjarte; Ottersen, Geir; Stenseth, Nils Chr.; Hjermann, Dag Ø.

2015-05-01

Understanding the causes of the large interannual fluctuations in the recruitment to many marine fishes is a key challenge in fisheries ecology. We here propose that the combination of mechanistic and statistical modelling of the pelagic early life stages (ELS) prior to recruitment can be a powerful approach for improving our understanding of local-scale and population-scale dynamics. Specifically, this approach allows separating effects of ocean transport and survival, and thereby enhances the knowledge of the processes that regulate recruitment. We analyse data on the pelagic eggs, larvae and post-larvae of Northeast Arctic cod and on copepod nauplii, the main prey of the cod larvae. The data originate from two surveys, one in spring and one in summer, for 30 years. A coupled physical-biological model is used to simulate the transport, ambient temperature and development of cod ELS from spawning through spring and summer. The predictions from this model are used as input in a statistical analysis of the summer data, to investigate effects of covariates thought to be linked to growth and survival. We find significant associations between the local-scale ambient copepod nauplii concentration and temperature in spring and the local-scale occurrence of cod (post)larvae in summer, consistent with effects on survival. Moreover, years with low copepod nauplii concentrations and low temperature in spring are significantly associated with lower mean length of the cod (post)larvae in summer, likely caused in part by higher mortality leading to increased dominance of young and hence small individuals. Finally, we find that the recruitment at age 3 is strongly associated with the mean body length of the cod ELS, highlighting the biological significance of the findings.

Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Atlantic silverside

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fay, C.W.; Neves, R.J.; Pardue, G.B.

1983-10-01

Species profiles are literature summaries of the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. They are prepared to assist in environmental impact assessment. The Atlantic silverside (Menidia menidia) is an important link in estuarine food webs as an opportunistic omnivore and as forage for large piscivores such as striped bass (Morone saxatilis) and bluefish (Pomatomus saltatrix). Many times the Atlantic silverside is the most abundant fish species encountered in estuaries and tributaries. They mature at age 1 and spawn in the intertidal zone of estuaries from March to June in the mid-Atlantic region. Few 2-year-oldmore » fish are ever encountered, so the Atlantic silverside is basically a short-lived species. Most spawning occurs at high tide during new or full moon phases. Eggs are adhesive and are found attached to submerged vegetation. Larvae, juveniles, and adults generally inhabit similar areas. Sex is determined in larval development 32 to 46 days after hatching, and is a function of parental genotype and water temperature regime during the critical period. Fisheries for this species are not documented. Eggs can tolerate water temperatures between 15/sup 0/ and 30/sup 0/C, and larvae need temperatures above 15/sup 0/C for survival. Larvae tolerate relatively acute temperature increases. Upper lethal temperatures for juveniles and adults range from 30.5/sup 0/ to 33.8/sup 0/C, depending on acclimation temperature. Salinities of 20 ppt or lower significantly delay hatching and affect larval survival. Juveniles and adults tolerate the full range of naturally occurring salinities (i.e., freshwater to at least 37.8 ppt). 57 references, 2 figures.« less

Genomic signatures of fine-scale local selection in Atlantic salmon suggest involvement of sexual maturation, energy homeostasis and immune defence-related genes.

PubMed

Pritchard, Victoria L; Mäkinen, Hannu; Vähä, Juha-Pekka; Erkinaro, Jaakko; Orell, Panu; Primmer, Craig R

2018-06-01

Elucidating the genetic basis of adaptation to the local environment can improve our understanding of how the diversity of life has evolved. In this study, we used a dense SNP array to identify candidate loci potentially underlying fine-scale local adaptation within a large Atlantic salmon (Salmo salar) population. By combining outlier, gene-environment association and haplotype homozygosity analyses, we identified multiple regions of the genome with strong evidence for diversifying selection. Several of these candidate regions had previously been identified in other studies, demonstrating that the same loci could be adaptively important in Atlantic salmon at subdrainage, regional and continental scales. Notably, we identified signals consistent with local selection around genes associated with variation in sexual maturation, energy homeostasis and immune defence. These included the large-effect age-at-maturity gene vgll3, the known obesity gene mc4r, and major histocompatibility complex II. Most strikingly, we confirmed a genomic region on Ssa09 that was extremely differentiated among subpopulations and that is also a candidate for local selection over the global range of Atlantic salmon. This region colocalized with a haplotype strongly associated with spawning ecotype in sockeye salmon (Oncorhynchus nerka), with circumstantial evidence that the same gene (six6) may be the selective target in both cases. The phenotypic effect of this region in Atlantic salmon remains cryptic, although allelic variation is related to upstream catchment area and covaries with timing of the return spawning migration. Our results further inform management of Atlantic salmon and open multiple avenues for future research. © 2018 John Wiley & Sons Ltd.

Gulf sturgeon spawning migration and habitat in the Choctawhatchee River system, Alabama-Florida

USGS Publications Warehouse

Fox, D.A.; Hightower, J.E.; Parauka, F.M.

2000-01-01

Information about spawning migration and spawning habitat is essential to maintain and ultimately restore populations of endangered and threatened species of anadromous fish. We used ultrasonic and radiotelemetry to monitor the movements of 35 adult Gulf sturgeon Acipenser oxyrinchus desotoi (a subspecies of the Atlantic sturgeon A. oxyrinchus) as they moved between Choctawhatchee Bay and the Choctawhatchee River system during the spring of 1996 and 1997. Histological analysis of gonadal biopsies was used to determine the sex and reproductive status of individuals. Telemetry results and egg sampling were used to identify Gulf sturgeon spawning sites and to examine the roles that sex and reproductive status play in migratory behavior. Fertilized Gulf sturgeon eggs were collected in six locations in both the upper Choctawhatchee and Pea rivers. Hard bottom substrate, steep banks, and relatively high flows characterized collection sites. Ripe Gulf sturgeon occupied these spawning areas from late March through early May, which included the interval when Gulf sturgeon eggs were collected. For both sexes, ripe fish entered the Choctawhatchee River significantly earlier and at a lower water temperature and migrated further upstream than did nonripe fish. Males entered the Choctawhatchee River at a lower water temperature than females. Results from histology and telemetry support the hypothesis that male Gulf sturgeon may spawn annually, whereas females require more than 1 year between spawning events. Upper river hard bottom areas appear important for the successful spawning of Gulf sturgeon, and care should be taken to protect against habitat loss or degradation of known spawning habitat.

Use of hydrolysates from Atlantic cod (Gadus morhua L.) viscera as a complex nitrogen source for lactic acid bacteria.

PubMed

Aspmo, Stein Ivar; Horn, Svein Jarle; Eijsink, Vincent G H

2005-07-01

Hydrolysates of cod viscera were tested as an alternative to commonly used complex nitrogen sources (peptones and/or extracts) for the type strains of the lactic acid bacteria Lactococcus lactis, Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus casei, Lactobacillus sakei and Pediococcus pentosaceus. Comparative studies with MRS-like media containing different nitrogen sources showed that all the fish hydrolysates performed equally well or better than commercial extracts/peptones for all selected lactic acid bacteria.

Microbiological, chemical and sensory spoilage analysis of raw Atlantic cod (Gadus morhua) stored under modified atmospheres.

PubMed

Kuuliala, L; Al Hage, Y; Ioannidis, A-G; Sader, M; Kerckhof, F-M; Vanderroost, M; Boon, N; De Baets, B; De Meulenaer, B; Ragaert, P; Devlieghere, F

2018-04-01

During fish spoilage, microbial metabolism leads to the production of volatile organic compounds (VOCs), characteristic off-odors and eventual consumer rejection. The aim of the present study was to contribute to the development of intelligent packaging technologies by identifying and quantifying VOCs that indicate spoilage of raw Atlantic cod (Gadus morhua) under atmospheres (%v/v CO 2 /O 2 /N 2 ) 60/40/0, 60/5/35 and air. Spoilage was examined by microbiological, chemical and sensory analyses over storage time at 4 or 8 °C. Selected-ion flow-tube mass spectrometry (SIFT-MS) was used for quantifying selected VOCs and amplicon sequencing of the 16S rRNA gene was used for the characterization of the cod microbiota. OTUs classified within the Photobacterium genus increased in relative abundance over time under all storage conditions, suggesting that Photobacterium contributed to spoilage and VOC production. The onset of exponential VOC concentration increase and sensory rejection occurred at high total plate counts (7-7.5 log). Monitoring of early spoilage thus calls for sensitivity for low VOC concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Predator transitory spillover induces trophic cascades in ecological sinks

PubMed Central

Casini, Michele; Blenckner, Thorsten; Möllmann, Christian; Gårdmark, Anna; Lindegren, Martin; Llope, Marcos; Kornilovs, Georgs; Plikshs, Maris; Stenseth, Nils Christian

2012-01-01

Understanding the effects of cross-system fluxes is fundamental in ecosystem ecology and biological conservation. Source-sink dynamics and spillover processes may link adjacent ecosystems by movement of organisms across system boundaries. However, effects of temporal variability in these cross-system fluxes on a whole marine ecosystem structure have not yet been presented. Here we show, using 35 y of multitrophic data series from the Baltic Sea, that transitory spillover of the top-predator cod from its main distribution area produces cascading effects in the whole food web of an adjacent and semi-isolated ecosystem. At varying population size, cod expand/contract their distribution range and invade/retreat from the neighboring Gulf of Riga, thereby affecting the local prey population of herring and, indirectly, zooplankton and phytoplankton via top-down control. The Gulf of Riga can be considered for cod a “true sink” habitat, where in the absence of immigration from the source areas of the central Baltic Sea the cod population goes extinct due to the absence of suitable spawning grounds. Our results add a metaecosystem perspective to the ongoing intense scientific debate on the key role of top predators in structuring natural systems. The integration of regional and local processes is central to predict species and ecosystem responses to future climate changes and ongoing anthropogenic disturbances. PMID:22505739

Atlantic cod actively avoid CO2 and predator odour, even after long-term CO2 exposure.

PubMed

Jutfelt, Fredrik; Hedgärde, Maria

2013-12-27

The rising atmospheric CO2 level is continuously driving the dissolution of more CO2 into the oceans, and some emission scenarios project that the surface waters may reach 1000 μatm by the end of the century. It is not known if fish can detect moderately elevated CO2 levels, and if they avoid areas with high CO2. If so, avoidance behaviour to water with high CO2 could affect movement patterns and migrations of fish in the future. It is also being increasingly recognized that fish behaviour can be altered by exposure to CO2. Therefore this study investigated how long-term exposure to elevated pCO2 affects predator avoidance and CO2 avoidance in juvenile Atlantic cod (Gadus morhua). The fish were exposed to control water or CO2-enriched water (1000 μatm) for six weeks before being subjected to tests of behaviour. Despite long term exposure to elevated pCO2 the cod still strongly avoided the smell of a predator. These data are surprising because several coral reef fish have demonstrated reversal of olfactory responses after CO2 exposure, turning avoidance of predator cues into preference for predator cues. Fish from both treatment groups also demonstrated strong avoidance of CO2 when presented with the choice of control or CO2-acidified water, indicating that habituation to the CO2 sensory stimuli is negligible. As Atlantic cod maintained normal behavioural responses to olfactory cues, they may be tolerant to CO2-induced behavioural changes. The results also suggest that despite the long-term exposure to CO2-acidified water, the fish still preferred the control water over CO2-acidified water. Therefore, in the future, fish may alter their movements and migrations in search of waters with a lower CO2 content.

Atlantic cod actively avoid CO2 and predator odour, even after long-term CO2 exposure

PubMed Central

2013-01-01

Introduction The rising atmospheric CO2 level is continuously driving the dissolution of more CO2 into the oceans, and some emission scenarios project that the surface waters may reach 1000 μatm by the end of the century. It is not known if fish can detect moderately elevated CO2 levels, and if they avoid areas with high CO2. If so, avoidance behaviour to water with high CO2 could affect movement patterns and migrations of fish in the future. It is also being increasingly recognized that fish behaviour can be altered by exposure to CO2. Therefore this study investigated how long-term exposure to elevated pCO2 affects predator avoidance and CO2 avoidance in juvenile Atlantic cod (Gadus morhua). The fish were exposed to control water or CO2-enriched water (1000 μatm) for six weeks before being subjected to tests of behaviour. Results Despite long term exposure to elevated pCO2 the cod still strongly avoided the smell of a predator. These data are surprising because several coral reef fish have demonstrated reversal of olfactory responses after CO2 exposure, turning avoidance of predator cues into preference for predator cues. Fish from both treatment groups also demonstrated strong avoidance of CO2 when presented with the choice of control or CO2-acidified water, indicating that habituation to the CO2 sensory stimuli is negligible. Conclusions As Atlantic cod maintained normal behavioural responses to olfactory cues, they may be tolerant to CO2-induced behavioural changes. The results also suggest that despite the long-term exposure to CO2-acidified water, the fish still preferred the control water over CO2-acidified water. Therefore, in the future, fish may alter their movements and migrations in search of waters with a lower CO2 content. PMID:24373523

Interspecific competition in tributaries: Prospectus for restoring Atlantic salmon in Lake Ontario

USGS Publications Warehouse

Johnson, James H.; Wedge, Leslie R.

1999-01-01

Historically, Lake Ontario may have supported the world's largest freshwater population of Atlantic salmon (Salmo salar). However, by the late 1800's, salmon were virtually extinct in the lake due to the damming of tributaries, overharvest, deforestation, and pollution. Of these factors, the building of dams on tributaries, which precluded access by the salmon to natal spawning streams, was probably the most detrimental. Since the extirpation of Atlantic salmon in the Lake Ontario watershed over a century ago, considerable change has occurred throughout the lake and tributary ecosystem. The changes within the ecosystem that may have the most profound effect on Atlantic salmon restoration include the presence of exotic species, including other salmonines, and reduced habitat quality, especially in tributaries. These changes must be taken into account when considering Atlantic salmon restoration.

Effects of sea lamprey substrate modification and carcass nutrients on macroinvertebrate assemblages in a small Atlantic coastal stream

USGS Publications Warehouse

Weaver, Daniel M.; Coghlan, Stephen M.; Zydlewski, Joseph D.

2018-01-01

Aquatic macroinvertebrates respond to patch dynamics arising from interactions of physical and chemical disturbances across space and time. Anadromous fish, such as sea lamprey, Petromyzon marinus, migrate from the ocean and alter physical and chemical properties of recipient spawning streams. Sea lamprey disturb stream benthos physically through nest construction and spawning, and enrich food webs through nutrient deposition from decomposing carcasses. Sea lamprey spawning nests support greater macroinvertebrate abundance than adjacent reference areas, but concurrent effects of stream bed modification and nutrient supplementation have not been examined sequentially. We added carcasses and cleared substrate experimentally to mimic the physical disturbance and nutrient enrichment associated with lamprey spawning, and characterized effects on macroinvertebrate assemblage structure. We found that areas receiving cleared substrate and carcass nutrients were colonized largely by Simuliidae compared to upstream and downstream control areas that were colonized largely by Hydropsychidae, Philopotamidae, and Chironomidae. Environmental factors such as stream flow likely shape assemblages by physically constraining macroinvertebrate establishment and feeding. Our results indicate potential changes in macroinvertebrate assemblages from the physical and chemical changes to streams brought by spawning populations of sea lamprey.

Oil droplet fouling and differential toxicokinetics of polycyclic aromatic hydrocarbons in embryos of Atlantic haddock and cod.

PubMed

Sørensen, Lisbet; Sørhus, Elin; Nordtug, Trond; Incardona, John P; Linbo, Tiffany L; Giovanetti, Laura; Karlsen, Ørjan; Meier, Sonnich

2017-01-01

The impact of crude oil pollution on early life stages (ELS) of fish, including larvae and embryos, has received considerable attention in recent years. Of the organic components present in crude oil, polycyclic aromatic hydrocarbons (PAHs) are considered the main class of compounds responsible for toxic effects in marine organisms. Although evidence suggests that they are more toxic, alkylated PAHs remain much less studied than their unsubstituted congeners. Recently, it was established that embryos of Atlantic haddock (Melanogrammus aeglefinus) are particularly sensitive to dispersed crude oil, and it was hypothesized that this was caused by direct interaction with crude oil droplets, which adhered to the chorion of exposed embryos. Such a phenomenon would increase the potential for uptake of less water-soluble compounds, including alkylated PAHs. In the current study, we compared the uptake of parent and alkylated PAHs in Atlantic cod (Gadus morhua) and haddock embryos exposed to dispersed crude oil at a range of environmentally relevant concentrations (10-600 μg oil/liter seawater). Although the species are biologically very similar, the cod chorion does not become fouled with oil droplets, even when the two species are exposed to dispersions of crude oil droplets under similar conditions. A close correlation between the degree of fouling and toxicological response (heart defects, craniofacial malformation) was observed. Oil droplet fouling in haddock led to both quantitative and qualitative differences in PAH uptake. Finally, kinetic data on a large suite of PAHs showed differential elimination, suggesting differential metabolism of unsubstituted versus alkylated compounds.

Quantitative proteomics analysis reveals perturbation of lipid metabolic pathways in the liver of Atlantic cod (Gadus morhua) treated with PCB 153.

PubMed

Yadetie, Fekadu; Oveland, Eystein; Døskeland, Anne; Berven, Frode; Goksøyr, Anders; Karlsen, Odd André

2017-04-01

PCB 153 is one of the most abundant PCB congeners detected in biological samples. It is a persistent compound that is still present in the environment despite the ban on production and use of PCBs in the late 1970s. It has strong tendencies to bioaccumulate and biomagnify in biota, and studies have suggested that it is an endocrine and metabolic disruptor. In order to study mechanisms of toxicity, we exposed Atlantic cod (Gadus morhua) to various doses of PCB 153 (0, 0.5, 2 and 8mg/kg body weight) for two weeks and examined the effects on expression of liver proteins using label-free quantitative proteomics. Label-free liquid chromatography-mass spectrometry analysis of the liver proteome resulted in the quantification of 1272 proteins, of which 78 proteins were differentially regulated in the PCB 153-treated dose groups compared to the control group. Functional enrichment analysis showed that pathways significantly affected are related to lipid metabolism, cytoskeletal remodeling, cell cycle and cell adhesion. Importantly, the main effects appear to be on lipid metabolism, with up-regulation of enzymes in the de novo fatty acid synthesis pathway, consistent with previous transcriptomics results. Increased plasma triglyceride levels were also observed in the PCB 153 treated fish, in agreement with the induction of the lipogenic genes and proteins. The results suggest that PCB 153 perturbs lipid metabolism in the Atlantic cod liver. Elevated levels of lipogenic enzymes and plasma triglycerides further suggest increased synthesis of fatty acids and triglycerides. Copyright © 2017 Elsevier B.V. All rights reserved.

Oil droplet fouling and differential toxicokinetics of polycyclic aromatic hydrocarbons in embryos of Atlantic haddock and cod

PubMed Central

Sørhus, Elin; Nordtug, Trond; Incardona, John P.; Linbo, Tiffany L.; Giovanetti, Laura; Karlsen, Ørjan; Meier, Sonnich

2017-01-01

The impact of crude oil pollution on early life stages (ELS) of fish, including larvae and embryos, has received considerable attention in recent years. Of the organic components present in crude oil, polycyclic aromatic hydrocarbons (PAHs) are considered the main class of compounds responsible for toxic effects in marine organisms. Although evidence suggests that they are more toxic, alkylated PAHs remain much less studied than their unsubstituted congeners. Recently, it was established that embryos of Atlantic haddock (Melanogrammus aeglefinus) are particularly sensitive to dispersed crude oil, and it was hypothesized that this was caused by direct interaction with crude oil droplets, which adhered to the chorion of exposed embryos. Such a phenomenon would increase the potential for uptake of less water-soluble compounds, including alkylated PAHs. In the current study, we compared the uptake of parent and alkylated PAHs in Atlantic cod (Gadus morhua) and haddock embryos exposed to dispersed crude oil at a range of environmentally relevant concentrations (10–600 μg oil/liter seawater). Although the species are biologically very similar, the cod chorion does not become fouled with oil droplets, even when the two species are exposed to dispersions of crude oil droplets under similar conditions. A close correlation between the degree of fouling and toxicological response (heart defects, craniofacial malformation) was observed. Oil droplet fouling in haddock led to both quantitative and qualitative differences in PAH uptake. Finally, kinetic data on a large suite of PAHs showed differential elimination, suggesting differential metabolism of unsubstituted versus alkylated compounds. PMID:28678887

Species detection using HyBeacon(®) probe technology: Working towards rapid onsite testing in non-human forensic and food authentication applications.

PubMed

Dawnay, Nick; Hughes, Rebecca; Court, Denise Syndercombe; Duxbury, Nicola

2016-01-01

Identifying individual species or determining species' composition in an unknown sample is important for a variety of forensic applications. Food authentication, monitoring illegal trade in endangered species, forensic entomology, sexual assault case work and counter terrorism are just some of the fields that can require the detection of the biological species present. Traditional laboratory based approaches employ a wide variety of tools and technologies and exploit a number of different species specific traits including morphology, molecular differences and immuno-chemical analyses. A large number of these approaches require laboratory based apparatus and results can take a number of days to be returned to investigating authorities. Having a presumptive test for rapid identification could lead to savings in terms of cost and time and allow sample prioritisation if confirmatory testing in a laboratory is required later. This model study describes the development of an assay using a single HyBeacon(®) probe and melt curve analyses allowing rapid screening and authentication of food products labelled as Atlantic cod (Gadus morhua). Exploiting melt curve detection of species specific SNP sites on the COI gene the test allows detection of a target species (Atlantic cod) and closely related species which may be used as substitutes. The assay has been designed for use with the Field Portable ParaDNA system, a molecular detection platform for non-expert users. The entire process from sampling to result takes approximately 75min. Validation studies were performed on both single source genomic DNA, mixed genomic DNA and commercial samples. Data suggests the assay has a lower limit of detection of 31 pg DNA. The specificity of the assay to Atlantic cod was measured by testing highly processed food samples including frozen, defrosted and cooked fish fillets as well as fish fingers, battered fish fillet and fish pie. Ninety-six (92.7%) of all Atlantic cod food products, tested, provided a correct single species result with the remaining samples erroneously identified as containing non-target species. The data shows that the assay was quick to design and characterise and is also capable of yielding results that would be beneficial in a variety of fields, not least the authentication of food. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Computer vision-based evaluation of pre- and postrigor changes in size and shape of Atlantic cod (Gadus morhua) and Atlantic salmon (Salmo salar) fillets during rigor mortis and ice storage: effects of perimortem handling stress.

PubMed

Misimi, E; Erikson, U; Digre, H; Skavhaug, A; Mathiassen, J R

2008-03-01

The present study describes the possibilities for using computer vision-based methods for the detection and monitoring of transient 2D and 3D changes in the geometry of a given product. The rigor contractions of unstressed and stressed fillets of Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) were used as a model system. Gradual changes in fillet shape and size (area, length, width, and roundness) were recorded for 7 and 3 d, respectively. Also, changes in fillet area and height (cross-section profiles) were tracked using a laser beam and a 3D digital camera. Another goal was to compare rigor developments of the 2 species of farmed fish, and whether perimortem stress affected the appearance of the fillets. Some significant changes in fillet size and shape were found (length, width, area, roundness, height) between unstressed and stressed fish during the course of rigor mortis as well as after ice storage (postrigor). However, the observed irreversible stress-related changes were small and would hardly mean anything for postrigor fish processors or consumers. The cod were less stressed (as defined by muscle biochemistry) than the salmon after the 2 species had been subjected to similar stress bouts. Consequently, the difference between the rigor courses of unstressed and stressed fish was more extreme in the case of salmon. However, the maximal whole fish rigor strength was judged to be about the same for both species. Moreover, the reductions in fillet area and length, as well as the increases in width, were basically of similar magnitude for both species. In fact, the increases in fillet roundness and cross-section height were larger for the cod. We conclude that the computer vision method can be used effectively for automated monitoring of changes in 2D and 3D shape and size of fish fillets during rigor mortis and ice storage. In addition, it can be used for grading of fillets according to uniformity in size and shape, as well as measurement of fillet yield measured in thickness. The methods are accurate, rapid, nondestructive, and contact-free and can therefore be regarded as suitable for industrial purposes.

Seasonal and annual variation in the diet of Atlantic cod (Gadus morhua) in relation to the abundance of capelin (Mallotus villosus) off eastern Newfoundland, Canada

USGS Publications Warehouse

Methven, David A.; Piatt, John F.

1989-01-01

The importance of capelin as prey for cod has long been known (Thompson, 1943; and see Lilly (1987) for a review); however, no studies have been conducted on how the highly dynamic seasonal and yearly variations in capelin abundance affect cod diet. We studied the occurrence of capelin in cod stomachs in relation to the relative abundance of capelin at Witless Bay, Newfoundland (47°15’N 52°46’W), during June, July and August, 1982-1984. The mean number of capelin per stomach and the per cent occurrence of stomachs containing capelin were determined for each collection of stomachs. A total of 680 stomachs were examined. Cod were sampled from those caught in gillnets by fishermen and averaged 66 cm ± 8 (s.d.) in 1983 and 62 cm ± 8 (s.d.) in 1984. Relative abundance of capelin in the local habitat was determined by conducting hydroacoustic surveys around Gull Island in Witless Bay, the same area where cod were collected for stomach content analysis. Only hydroacoustic surveys conducted within three days of cod stomach collections were analyzed. Further details of hydroacoustic surveys including quantifications of acoustic echograms are described in Piatt (1989).

Feeding habits of the Atlantic bluefin tuna, Thunnus thynnus (L. 1758), in the central Mediterranean Sea (Strait of Messina)

NASA Astrophysics Data System (ADS)

Battaglia, Pietro; Andaloro, Franco; Consoli, Pierpaolo; Esposito, Valentina; Malara, Danilo; Musolino, Simona; Pedà, Cristina; Romeo, Teresa

2013-03-01

The study of feeding habits of the Atlantic bluefin tuna was carried out in 123 specimens, ranging from 115 to 222 cm fork length (FL) and collected during spring seasons of 2010 and 2011 in the central Mediterranean Sea (Strait of Messina). The analysis of stomach contents allowed us to identify 91 taxa of prey items, mainly belonging to Teleostea (54), Cephalopoda (20) and Crustacea (13). The percentage of index of relative abundance ( IRI) shows the highest values for the myctophid Hygophum benoiti (% IRI = 22.854) and the stomiid Chauliodus sloani (% IRI = 15.124), followed by the oegopsid squid Illex coindetii (% IRI = 14.316). The broad spectrum of prey items could suggest a generalist behavior of this predator, with several species that occasionally occurs in its diet. However, if prey are grouped into food categories, the importance of mesopelagic and benthopelagic fishes can be appreciated (54.41 % of % IRI). The assessment of the hypothetical foraging rhythm of the Atlantic bluefin tuna highlighted that its feeding activity is concentrated on diel migrating fauna during night and on larger preys upon daylight. The predation on the high-energetic food as mesopelagic and bathypelagic fishes during the pre-spawning and the spawning period may bring an energetic advantage in tuna metabolism and gonadal maturation

Reproductive strategies and seasonal changes in the somatic indices of seven small-bodied fishes in Atlantic Canada in relation to study design for environmental effects monitoring.

PubMed

Barrett, Timothy J; Brasfield, Sandra M; Carroll, Leslie C; Doyle, Meghan A; van den Heuvel, Michael R; Munkittrick, Kelly R

2015-05-01

Small-bodied fishes are more commonly being used in environmental effects monitoring (EEM) studies. There is a lack of understanding of the biological characteristics of many small-bodied species, which hinders study designs for monitoring studies. For example, 72% of fish population surveys in Canada's EEM program for pulp and paper mills that used small-bodied fishes were conducted outside of the reproductive period of the species. This resulted in an inadequate assessment of the EEM program's primary effect endpoint (reproduction) for these studies. The present study examined seasonal changes in liver size, gonad size, and condition in seven freshwater and estuarine small-bodied fishes in Atlantic Canada. These data were used to examine differences in reproductive strategies and patterns of energy storage among species. Female gonadal recrudescence in all seven species began primarily in the 2-month period in the spring before spawning. Male gonadal development was concurrent with females in five species; however, gonadal recrudescence began in the fall in male three-spined stickleback (Gasterosteus aculeatus) and slimy sculpin (Cottus cognatus). The spawning period for each species was estimated from the decline in relative ovary size after its seasonal maximum value in spring. The duration of the spawning period reflected the reproductive strategy (single vs multiple spawning) of the species. Optimal sampling periods to assess reproductive impacts in each species were determined based on seasonal changes in ovary size and were identified to be during the prespawning period when gonads are developing and variability in relative gonad size is at a minimum.

Harbour porpoises respond to climate change

PubMed Central

Heide-Jørgensen, Mads Peter; Iversen, Maria; Nielsen, Nynne Hjort; Lockyer, Christina; Stern, Harry; Ribergaard, Mads Hvid

2011-01-01

The effects of climate change on marine ecosystems and in particular on marine top predators are difficult to assess due to, among other things, spatial variability, and lack of clear delineation of marine habitats. The banks of West Greenland are located in a climate sensitive area and are likely to elicit pronounced responses to oceanographic changes in the North Atlantic. The recent increase in sea temperatures on the banks of West Greenland has had cascading effects on sea ice coverage, residency of top predators, and abundance of important prey species like Atlantic cod (Gadus morhua). Here, we report on the response of one of the top predators in West Greenland; the harbour porpoise (Phocoena phocoena). The porpoises depend on locating high densities of prey species with high nutritive value and they have apparently responded to the general warming on the banks of West Greenland by longer residence times, increased consumption of Atlantic cod resulting in improved body condition in the form of larger fat deposits in blubber, compared to the situation during a cold period in the 1990s. This is one of the few examples of a measurable effect of climate change on a marine mammal population. PMID:22393524

Harbour porpoises respond to climate change.

PubMed

Heide-Jørgensen, Mads Peter; Iversen, Maria; Nielsen, Nynne Hjort; Lockyer, Christina; Stern, Harry; Ribergaard, Mads Hvid

2011-12-01

The effects of climate change on marine ecosystems and in particular on marine top predators are difficult to assess due to, among other things, spatial variability, and lack of clear delineation of marine habitats. The banks of West Greenland are located in a climate sensitive area and are likely to elicit pronounced responses to oceanographic changes in the North Atlantic. The recent increase in sea temperatures on the banks of West Greenland has had cascading effects on sea ice coverage, residency of top predators, and abundance of important prey species like Atlantic cod (Gadus morhua). Here, we report on the response of one of the top predators in West Greenland; the harbour porpoise (Phocoena phocoena). The porpoises depend on locating high densities of prey species with high nutritive value and they have apparently responded to the general warming on the banks of West Greenland by longer residence times, increased consumption of Atlantic cod resulting in improved body condition in the form of larger fat deposits in blubber, compared to the situation during a cold period in the 1990s. This is one of the few examples of a measurable effect of climate change on a marine mammal population.

Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic). Striped Bass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fay, C.W.; Neves, R.J.; Pardue, G.B.

1983-10-01

Species profiles are literature summaries on the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. The striped bass (Morone saxatilis) is a highly valued recreational and commercial fish species and is surpassed in total recreational catch (weight) only by bluefish and Atlantic mackerel on the Atlantic coast. Males mature at age 2 or 3, and females at age 4 or 5. Striped bass are anadromous, spawning in fresh or nearly fresh water, from April through June in the Mid-Atlantic region. Upper Chesapeake Bay, its major tributaries, and the Chesapeake-Delaware Canal are the most important spawning groundsmore » on the Atlantic coast. Eggs are semibuoyant, and require a minimum current velocity of 30.5 cm/s during development to keep them from settling and smothering on the bottom. Environmental conditions during the larval stage are considered most crucial in terms of future year class strength. Juveniles remain in or near areas of origin for 2 or 3 years, at which time a portion of the juveniles may join coastal migratory stocks, moving north in spring and summer and south in fall and winter. Temperature, salinity, current velocity, and turbidity are important environmental factors for striped bass. Eggs require water temperatures between 14/sup 0/C and 23/sup 0/C, salinities between 0 and 10 ppt, water currents of at least 30.5 cm/s, and turbidities less than 1000 mg/l for successful development and hatching. Larvae require temperatures between 10/sup 0/C and 25/sup 0/C, salinities between 0 and 15 ppt, and turbidities less than 500 mg/1 for survival. Juvenile and adult tolerances are generally wider. 171 references, 4 figures, 9 tables.« less

A comparison of fisheries biological reference points estimated from temperature-specific multi-species and single-species climate-enhanced stock assessment models

NASA Astrophysics Data System (ADS)

Holsman, Kirstin K.; Ianelli, James; Aydin, Kerim; Punt, André E.; Moffitt, Elizabeth A.

2016-12-01

Multi-species statistical catch at age models (MSCAA) can quantify interacting effects of climate and fisheries harvest on species populations, and evaluate management trade-offs for fisheries that target several species in a food web. We modified an existing MSCAA model to include temperature-specific growth and predation rates and applied the modified model to three fish species, walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus) and arrowtooth flounder (Atheresthes stomias), from the eastern Bering Sea (USA). We fit the model to data from 1979 through 2012, with and without trophic interactions and temperature effects, and use projections to derive single- and multi-species biological reference points (BRP and MBRP, respectively) for fisheries management. The multi-species model achieved a higher over-all goodness of fit to the data (i.e. lower negative log-likelihood) for pollock and Pacific cod. Variability from water temperature typically resulted in 5-15% changes in spawning, survey, and total biomasses, but did not strongly impact recruitment estimates or mortality. Despite this, inclusion of temperature in projections did have a strong effect on BRPs, including recommended yield, which were higher in single-species models for Pacific cod and arrowtooth flounder that included temperature compared to the same models without temperature effects. While the temperature-driven multi-species model resulted in higher yield MBPRs for arrowtooth flounder than the same model without temperature, we did not observe the same patterns in multi-species models for pollock and Pacific cod, where variability between harvest scenarios and predation greatly exceeded temperature-driven variability in yield MBRPs. Annual predation on juvenile pollock (primarily cannibalism) in the multi-species model was 2-5 times the annual harvest of adult fish in the system, thus predation represents a strong control on population dynamics that exceeds temperature-driven changes to growth and is attenuated through harvest-driven reductions in predator populations. Additionally, although we observed differences in spawning biomasses at the accepted biological catch (ABC) proxy between harvest scenarios and single- and multi-species models, discrepancies in spawning stock biomass estimates did not translate to large differences in yield. We found that multi-species models produced higher estimates of combined yield for aggregate maximum sustainable yield (MSY) targets than single species models, but were more conservative than single-species models when individual MSY targets were used, with the exception of scenarios where minimum biomass thresholds were imposed. Collectively our results suggest that climate and trophic drivers can interact to affect MBRPs, but for prey species with high predation rates, trophic- and management-driven changes may exceed direct effects of temperature on growth and predation. Additionally, MBRPs are not inherently more conservative than single-species BRPs. This framework provides a basis for the application of MSCAA models for tactical ecosystem-based fisheries management decisions under changing climate conditions.

Effects of hypoxic exposure during feeding on SDA and postprandial cardiovascular physiology in the Atlantic cod, Gadus morhua.

PubMed

Behrens, Jane W; Axelsson, Michael; Neuenfeldt, Stefan; Seth, Henrik

2012-01-01

Some Atlantic cod in the Bornholm Basin undertake vertical foraging migrations into severely hypoxic bottom water. Hypoxic conditions can reduce the postprandial increase in gastrointestinal blood flow (GBF). This could subsequently postpone or reduce the postprandial increase in oxygen consumption (MO(2)), i.e. the SDA, leading to a disturbed digestion. Additionally, a restricted oxygen uptake could result in an oxygen debt that needs to be compensated for upon return to normoxic waters and this may also affect the ability to process the food. Long-term cardio-respiratory measurements were made on fed G. morhua in order to understand how the cardio-respiratory system of feeding fish respond to a period of hypoxia and a subsequent return to normoxia. These were exposed to 35% water oxygen saturation for 90 minutes, equivalent to the time and oxygen level cod voluntarily endure when searching for food in the Bornholm Basin. We found that i) gastric and intestinal blood flows, cardiac output and MO(2) increased after feeding, ii) gastric and intestinal blood flows were spared in hypoxia, and iii) there were no indications of an oxygen debt at the end of the hypoxic period. The magnitude and time course of the measured variables are similar to values obtained from fish not exposed to the hypoxic period. In conclusion, when cod in the field search for and ingest prey under moderate hypoxic conditions they appear to stay within safe limits of oxygen availability as we saw no indications of an oxygen debt, or negative influence on digestive capacity, when simulating field observations.

Effects of amino acid supplementations on metabolic and physiological parameters in Atlantic cod (Gadus morhua) under stress.

PubMed

Herrera, Marcelino; Herves, María Antonia; Giráldez, Inmaculada; Skar, Kristin; Mogren, Hanne; Mortensen, Atle; Puvanendran, Velmurugu

2017-04-01

The effects of tryptophan (Trp) and phenylalanine (Phe) diet supplementation on the stress and metabolism of the Atlantic cod have been studied. Fish were fed diet supplemented with Trp or Phe or control diet for 1 week. At the end of the feeding trial, fish were subjected to air exposure or heat shock. Following samples of blood, liver and muscle were taken from the fish and were analyzed for stress and metabolic indicators. After an air exposure, plasma cortisol levels in fish fed with Trp and Phe diets were lower compared to the fish fed the control diet. Diets containing both amino acids increased significantly the liver transaminase activities in juvenile cod. During thermal stress, high Trp contents had significant effects on fructose biphosphatase activity though Phe did not. Overall, activities of glucose 6-phosphate dehydrogenase, pyruvate kinase, and phosphofructokinase increased significantly for both amino acid diets. For the thermal stress, fish had the highest values of those activities for the 3Trp diet. Trp content in the diet had significant effects on the transaminase activity in muscle during air stress compared to fish fed control and Phe diets. Muscle alanine transaminase activity for thermal stress in fish fed any diet was not significantly different from the control. Both Trp and Phe supplementations reduced the stress markers in the cod; hence, they could be used as additives for the stress attenuation. However, they also raised the activity of key enzymes in glycolysis and gluconeogenesis, mainly the Trp diets.

Adhesion of mechanically and chemically dispersed crude oil droplets to eggs of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus).

PubMed

Hansen, Bjørn Henrik; Sørensen, Lisbet; Carvalho, Patricia Almeira; Meier, Sonnich; Booth, Andy M; Altin, Dag; Farkas, Julia; Nordtug, Trond

2018-05-30

Crude oil accidentally spilled into the marine environment undergoes natural weathering processes that result in oil components being dissolved into the water column or present in particulate form as dispersed oil droplets. Oil components dissolved in seawater are typically considered as more bioavailable to pelagic marine organisms and the main driver of crude oil toxicity, however, recent studies indicate that oil droplets may also contribute. The adhesion of crude oil droplets onto the eggs of pelagic fish species may cause enhanced transfer of oil components via the egg surface causing toxicity during the sensitive embryonic developmental stage. In the current study, we utilized an oil droplet dispersion generator to generate defined oil droplets sizes/concentrations and exposed Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) to investigate if the potential for dispersed oil droplets to adhere onto the surface of eggs was species-dependent. The influence of a commercial chemical dispersant on the adhesion process was also studied. A key finding was that the adhesion of oil droplets was significantly higher for haddock than cod, highlighting key differences and exposure risks between the two species. Scanning electron microscopy indicates that the differences in oil droplet adhesion may be driven by the surface morphology of the eggs. Another important finding was that the adhesion capacity of oil droplets to fish eggs is significantly reduced (cod 37.3%, haddock 41.7%) in the presence of the chemical dispersant. Copyright © 2018 Elsevier B.V. All rights reserved.

iss055e023770

NASA Image and Video Library

2018-04-14

iss055e023770 (April 14, 2018) --- The southeast geography of the state of Massachusetts including Cape Cod Bay, Martha's Vineyard, Nantucket and the arm-shaped peninsula is clearly seen from the International Space Station as it orbited over the Atlantic coast of the United States.

Multiple SNP Markers Reveal Fine-Scale Population and Deep Phylogeographic Structure in European Anchovy (Engraulis encrasicolus L.)

PubMed Central

Zarraonaindia, Iratxe; Iriondo, Mikel; Albaina, Aitor; Pardo, Miguel Angel; Manzano, Carmen; Grant, W. Stewart; Irigoien, Xabier; Estonba, Andone

2012-01-01

Geographic surveys of allozymes, microsatellites, nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) have detected several genetic subdivisions among European anchovy populations. However, these studies have been limited in their power to detect some aspects of population structure by the use of a single or a few molecular markers, or by limited geographic sampling. We use a multi-marker approach, 47 nDNA and 15 mtDNA single nucleotide polymorphisms (SNPs), to analyze 626 European anchovies from the whole range of the species to resolve shallow and deep levels of population structure. Nuclear SNPs define 10 genetic entities within two larger genetically distinctive groups associated with oceanic variables and different life-history traits. MtDNA SNPs define two deep phylogroups that reflect ancient dispersals and colonizations. These markers define two ecological groups. One major group of Iberian-Atlantic populations is associated with upwelling areas on narrow continental shelves and includes populations spawning and overwintering in coastal areas. A second major group includes northern populations in the North East (NE) Atlantic (including the Bay of Biscay) and the Mediterranean and is associated with wide continental shelves with local larval retention currents. This group tends to spawn and overwinter in oceanic areas. These two groups encompass ten populations that differ from previously defined management stocks in the Alboran Sea, Iberian-Atlantic and Bay of Biscay regions. In addition, a new North Sea-English Channel stock is defined. SNPs indicate that some populations in the Bay of Biscay are genetically closer to North Western (NW) Mediterranean populations than to other populations in the NE Atlantic, likely due to colonizations of the Bay of Biscay and NW Mediterranean by migrants from a common ancestral population. Northern NE Atlantic populations were subsequently established by migrants from the Bay of Biscay. Populations along the Iberian-Atlantic coast appear to have been founded by secondary waves of migrants from a southern refuge. PMID:22860082

Spatial ecology of coastal Atlantic cod Gadus morhua associated with parasite load.

PubMed

Aalvik, I M; Moland, E; Olsen, E M; Stenseth, N C

2015-08-01

Acoustic tags and receivers were used to investigate the spatial ecology of coastal Atlantic cod Gadus morhua (n = 32, mean fork length: 50 cm, range: 33-80 cm) on the Norwegian Skagerrak coast in 2012. Monthly home ranges (HR), swimming activity and depth use varied considerably among individuals and through the months of June, July and August. HR sizes for the period ranged from 0.25 to 5.20 km2 (mean = 2.30 km2. Two thirds of the tagged G. morhua were infected with black spot disease Cryptocotyle lingua parasites; these fish had larger HRs and occupied deeper water compared with non-infected fish. The infected fish also tended to be more active in terms of horizontal swimming. From an ecological and evolutionary perspective, any environmental change that modifies G. morhua behaviour may therefore also alter the parasite load of the population, and its conservation and fishery status. © 2015 The Fisheries Society of the British Isles.

The removal of As(III) and As(V) from aqueous solutions by waste materials.

PubMed

Rahaman, M S; Basu, A; Islam, M R

2008-05-01

The use of different waste materials such as Atlantic Cod fish scale, chicken fat, coconut fibre and charcoal in removing arsenic [As(III) and As(V)] from aqueous solutions was investigated. Initial experimental runs, conducted for both As(III) and As(V) with the aforementioned materials, demonstrated the potential of using Atlantic Cod fish scale in removing both species of arsenic from aqueous streams. Therefore, the biosorbent fish scale was selected for further investigations and various parameters such as residence time, adsorbent dose, initial concentration of adsorbate, grain size of the adsorbent and pH of the bulk phase were studied to establish optimum conditions. The maximum adsorption capacity was observed at pH value 4.0. The equilibrium adsorption data were interpreted by using both Freundlich and Langmuir models. Rapid small-scale column tests (RSSCT) were also performed to determine the breakthrough characteristics of the arsenic species with respect to packed biosorbent columns.

New England Cod Collapse and the Climate.

PubMed

Meng, Kyle C; Oremus, Kimberly L; Gaines, Steven D

2016-01-01

To improve fishery management, there is an increasing need to understand the long-term consequences of natural and anthropogenic climate variability for ecological systems. New England's iconic cod populations have been in decline for several decades and have recently reached unprecedented lows. We find that 17% of the overall decline in Gulf of Maine cod biomass since 1980 can be attributed to positive phases of the North Atlantic Oscillation (NAO). This is a consequence of three results: i) a 1-unit increase in the NAO winter index is associated with a 17% decrease in the spring biomass of age-1 cod the following year; ii) this NAO-driven decrease persists as the affected cohort matures; iii) fishing practices appear to exacerbate NAO's direct biological effect such that, since 1913, a 1-unit increase in the NAO index lowers subsequent cod catch for up to 19 years. The Georges Bank cod stock displays similar patterns. Because we statistically detect a delay between the NAO and subsequent declines in adult biomass, our findings imply that observed current NAO conditions can be used in stock forecasts, providing lead time for adaptive policy. More broadly, our approach can inform forecasting efforts for other fish populations strongly affected by natural and anthropogenic climatic variation.

New England Cod Collapse and the Climate

PubMed Central

Meng, Kyle C.; Oremus, Kimberly L.; Gaines, Steven D.

2016-01-01

To improve fishery management, there is an increasing need to understand the long-term consequences of natural and anthropogenic climate variability for ecological systems. New England’s iconic cod populations have been in decline for several decades and have recently reached unprecedented lows. We find that 17% of the overall decline in Gulf of Maine cod biomass since 1980 can be attributed to positive phases of the North Atlantic Oscillation (NAO). This is a consequence of three results: i) a 1-unit increase in the NAO winter index is associated with a 17% decrease in the spring biomass of age-1 cod the following year; ii) this NAO-driven decrease persists as the affected cohort matures; iii) fishing practices appear to exacerbate NAO’s direct biological effect such that, since 1913, a 1-unit increase in the NAO index lowers subsequent cod catch for up to 19 years. The Georges Bank cod stock displays similar patterns. Because we statistically detect a delay between the NAO and subsequent declines in adult biomass, our findings imply that observed current NAO conditions can be used in stock forecasts, providing lead time for adaptive policy. More broadly, our approach can inform forecasting efforts for other fish populations strongly affected by natural and anthropogenic climatic variation. PMID:27463967

The Ontogeny and Brain Distribution Dynamics of the Appetite Regulators NPY, CART and pOX in Larval Atlantic Cod (Gadus morhua L.)

PubMed Central

Le, Hoang T. M. D.; Angotzi, Anna Rita; Ebbesson, Lars O. E.; Karlsen, Ørjan

2016-01-01

Similar to many marine teleost species, Atlantic cod undergo remarkable physiological changes during the early life stages with concurrent and profound changes in feeding biology and ecology. In contrast to the digestive system, very little is known about the ontogeny and the localization of the centers that control appetite and feed ingestion in the developing brain of fish. We examined the expression patterns of three appetite regulating factors (orexigenic: neuropeptide Y, NPY; prepro-orexin, pOX and anorexigenic: cocaine- and amphetamine-regulated transcript, CART) in discrete brain regions of developing Atlantic cod using chromogenic and double fluorescent in situ hybridization. Differential temporal and spatial expression patterns for each appetite regulator were found from first feeding (4 days post hatch; dph) to juvenile stage (76 dph). Neurons expressing NPY mRNA were detected in the telencephalon (highest expression), diencephalon, and optic tectum from 4 dph onward. CART mRNA expression had a wider distribution along the anterior-posterior brain axis, including both telencephalon and diencephalon from 4 dph. From 46 dph, CART transcripts were also detected in the olfactory bulb, region of the nucleus of medial longitudinal fascicle, optic tectum and midbrain tegmentum. At 4 and 20 dph, pOX mRNA expression was exclusively found in the preoptic region, but extended to the hypothalamus at 46 and 76 dph. Co-expression of both CART and pOX genes were also observed in several hypothalamic neurons throughout larval development. Our results show that both orexigenic and anorexigenic factors are present in the telencephalon, diencephalon and mesencephalon in cod larvae. The telencephalon mostly contains key factors of hunger control (NPY), while the diencephalon, and particularly the hypothalamus may have a more complex role in modulating the multifunctional control of appetite in this species. As the larvae develop, the overall progression in temporal and spatial complexity of NPY, CART and pOX mRNAs expression might be correlated to the maturation of appetite control regulation. These observations suggest that teleost larvae continue to develop the regulatory networks underlying appetite control after onset of exogenous feeding. PMID:27100086

The Ontogeny and Brain Distribution Dynamics of the Appetite Regulators NPY, CART and pOX in Larval Atlantic Cod (Gadus morhua L.).

PubMed

Le, Hoang T M D; Angotzi, Anna Rita; Ebbesson, Lars O E; Karlsen, Ørjan; Rønnestad, Ivar

2016-01-01

Similar to many marine teleost species, Atlantic cod undergo remarkable physiological changes during the early life stages with concurrent and profound changes in feeding biology and ecology. In contrast to the digestive system, very little is known about the ontogeny and the localization of the centers that control appetite and feed ingestion in the developing brain of fish. We examined the expression patterns of three appetite regulating factors (orexigenic: neuropeptide Y, NPY; prepro-orexin, pOX and anorexigenic: cocaine- and amphetamine-regulated transcript, CART) in discrete brain regions of developing Atlantic cod using chromogenic and double fluorescent in situ hybridization. Differential temporal and spatial expression patterns for each appetite regulator were found from first feeding (4 days post hatch; dph) to juvenile stage (76 dph). Neurons expressing NPY mRNA were detected in the telencephalon (highest expression), diencephalon, and optic tectum from 4 dph onward. CART mRNA expression had a wider distribution along the anterior-posterior brain axis, including both telencephalon and diencephalon from 4 dph. From 46 dph, CART transcripts were also detected in the olfactory bulb, region of the nucleus of medial longitudinal fascicle, optic tectum and midbrain tegmentum. At 4 and 20 dph, pOX mRNA expression was exclusively found in the preoptic region, but extended to the hypothalamus at 46 and 76 dph. Co-expression of both CART and pOX genes were also observed in several hypothalamic neurons throughout larval development. Our results show that both orexigenic and anorexigenic factors are present in the telencephalon, diencephalon and mesencephalon in cod larvae. The telencephalon mostly contains key factors of hunger control (NPY), while the diencephalon, and particularly the hypothalamus may have a more complex role in modulating the multifunctional control of appetite in this species. As the larvae develop, the overall progression in temporal and spatial complexity of NPY, CART and pOX mRNAs expression might be correlated to the maturation of appetite control regulation. These observations suggest that teleost larvae continue to develop the regulatory networks underlying appetite control after onset of exogenous feeding.

Trans-species polymorphism at antimicrobial innate immunity cathelicidin genes of Atlantic cod and related species

PubMed Central

Árnason, Einar

2015-01-01

Natural selection, the most important force in evolution, comes in three forms. Negative purifying selection removes deleterious variation and maintains adaptations. Positive directional selection fixes beneficial variants, producing new adaptations. Balancing selection maintains variation in a population. Important mechanisms of balancing selection include heterozygote advantage, frequency-dependent advantage of rarity, and local and fluctuating episodic selection. A rare pathogen gains an advantage because host defenses are predominantly effective against prevalent types. Similarly, a rare immune variant gives its host an advantage because the prevalent pathogens cannot escape the host’s apostatic defense. Due to the stochastic nature of evolution, neutral variation may accumulate on genealogical branches, but trans-species polymorphisms are rare under neutrality and are strong evidence for balancing selection. Balanced polymorphism maintains diversity at the major histocompatibility complex (MHC) in vertebrates. The Atlantic cod is missing genes for both MHC-II and CD4, vital parts of the adaptive immune system. Nevertheless, cod are healthy in their ecological niche, maintaining large populations that support major commercial fisheries. Innate immunity is of interest from an evolutionary perspective, particularly in taxa lacking adaptive immunity. Here, we analyze extensive amino acid and nucleotide polymorphisms of the cathelicidin gene family in Atlantic cod and closely related taxa. There are three major clusters, Cath1, Cath2, and Cath3, that we consider to be paralogous genes. There is extensive nucleotide and amino acid allelic variation between and within clusters. The major feature of the results is that the variation clusters by alleles and not by species in phylogenetic trees and discriminant analysis of principal components. Variation within the three groups shows trans-species polymorphism that is older than speciation and that is suggestive of balancing selection maintaining the variation. Using Bayesian and likelihood methods positive and negative selection is evident at sites in the conserved part of the genes and, to a larger extent, in the active part which also shows episodic diversifying selection, further supporting the argument for balancing selection. PMID:26038731

A narrow hybrid zone between two Cottus species in Wills Creek, Potomac drainage.

PubMed

Kinziger, A P; Raesly, R L

2001-01-01

We describe a narrow hybrid zone between the mottled sculpin (Cottus b. bairdi) and the Blue Ridge sculpin (C. caeruleomentum). Seven characters (dorsal fin rays, pectoral fin rays, caudal base band condition, male spawning coloration, and one frequency and two fixed allozyme differences) distinguish the two taxa in the hybrid zone. C. caeruleomentum and C. b. bairdi diverged in these characters in allopatry as indicated by their distribution on opposite sides of the Atlantic-Ohio divide. However, a stream capture placed these two taxa in secondary contact in Wills Creek, Potomac drainage (Atlantic slope). Allozyme data indicate the presence of post-F(1) hybrids in the zone of secondary contact. Changes in allozymes, morphology, and spawning coloration along a transect in Wills Creek reveal the hybrid zone is less than 20 river kilometers in length. Estimates of root mean square dispersal and gene flow tentatively suggest that selection is operating in the Wills Creek hybrid zone. C. b. bairdi and C. caeruleomentum are maintaining their identity in seven distinguishing characters on opposite ends of the hybrid zone revealing these two taxa are independent evolutionary lineages.

On the occurrence of egg masses of the diamond-shaped squid Thysanoteuthis rhombus Troschel, 1857 in the subtropical eastern Atlantic (Canary Islands). A potential commercial species?

PubMed Central

Pérez, Alejandro Escánez; Elena, Rodrigo Riera; González, Ángel Francisco González; Sierra, Ángel Guerra

2012-01-01

Abstract Data on opportunistic sightings of diamond-shaped squid Thysanoteuthis rhombus egg masses in the Canary Islands (Atlantic Ocean) are presented. A total of 16 egg masses of this species were recorded and photographed from 2000 to 2010 around the western islands of the archipelago (El Hierro, Tenerife and La Gomera). These data reveal the existence of an important spawning area for diamond-shaped squid around the Canary Islands, in subtropical east Atlantic waters. We provide preliminary data for the potential development of an artisanal fishery focused on this species, and a discussion on its potential impacts on the marine ecosystem. PMID:23129987

Interdecadal heterogeneity in mitochondrial DNA of Atlantic haddock (Melanogrammus aeglefinus) from Georges Bank.

PubMed

Purcell, M K; Kornfield, I; Fogarty, M; Parker, A

1996-09-01

Atlantic haddock of Georges Bank are characterized by large fluctuations in population size and a recent collapse of the commercial fishery. DNA extracted from dried scales of Georges Bank haddock, archived by the U.S. National Marine Fisheries Service (NMFS), reveals significant heterogeneity in frequencies of four mitochondrial DNA control region haplotypes between 1975 and 1985 cohorts. Several processes may be responsible for this temporal variation, the most attractive hypothesis being that haddock from other geographic regions episodically contribute to the Georges Bank gene pool. Thus, the population of haddock spawning on Georges Bank may not be genetically discrete and, with respect to Atlantic haddock, Georges Bank may not be viewed as a closed system.

Forecasting future recruitment success for Atlantic cod in the warming and acidifying Barents Sea.

PubMed

Koenigstein, Stefan; Dahlke, Flemming T; Stiasny, Martina H; Storch, Daniela; Clemmesen, Catriona; Pörtner, Hans-Otto

2018-01-01

Productivity of marine fish stocks is known to be affected by environmental and ecological drivers, and global climate change is anticipated to alter recruitment success of many stocks. While the direct effects of environmental drivers on fish early life stage survival can be quantified experimentally, indirect effects in marine ecosystems and the role of adaptation are still highly uncertain. We developed an integrative model for the effects of ocean warming and acidification on the early life stages of Atlantic cod in the Barents Sea, termed SCREI (Simulator of Cod Recruitment under Environmental Influences). Experimental results on temperature and CO 2 effects on egg fertilization, egg and larval survival and development times are incorporated. Calibration using empirical time series of egg production, temperature, food and predator abundance reproduces age-0 recruitment over three decades. We project trajectories of recruitment success under different scenarios and quantify confidence limits based on variation in experiments. A publicly accessible web version of the SCREI model can be run under www.oceanchange.uni-bremen.de/;SCREI. Severe reductions in average age-0 recruitment success of Barents Sea cod are projected under uncompensated warming and acidification toward the middle to end of this century. Although high population stochasticity was found, considerable rates of evolutionary adaptation to acidification and shifts in organismal thermal windows would be needed to buffer impacts on recruitment. While increases in food availability may mitigate short-term impacts, an increase in egg production achieved by stock management could provide more long-term safety for cod recruitment success. The SCREI model provides a novel integration of multiple driver effects in different life stages and enables an estimation of uncertainty associated with interindividual and ecological variation. The model thus helps to advance toward an improved empirical foundation for quantifying climate change impacts on marine fish recruitment, relevant for ecosystem-based assessments of marine systems under climate change. © 2017 John Wiley & Sons Ltd.

Trophic Ecology of Atlantic Bluefin Tuna (Thunnusthynnus) Larvae from the Gulf of Mexico and NW Mediterranean Spawning Grounds: A Comparative Stable Isotope Study

PubMed Central

Malca, Estrella; Quintanilla, José María; Muhling, Barbara A.; Alemany, Francisco; Privoznik, Sarah L.; Shiroza, Akihiro; Lamkin, John T.; García, Alberto

2015-01-01

The present study uses stable isotopes of nitrogen and carbon (δ15Nandδ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6–10 mm standard length) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). These regions are differentiated by their temperature regime and relative productivity, with the GOM being significantly warmer and more productive. MED BFT larvae showed the highest δ15N signatures, implying an elevated trophic position above the underlying microzooplankton baseline. Ontogenetic dietary shifts were observed in the BFT larvae from the GOM and MED which indicates early life trophodynamics differences between these spawning habitats. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their growth during their early life stages.These low δ15N levels in the zooplankton from the GOM may be an indication of a shifting isotopic baseline in pelagic food webs due to diatrophic inputs by cyanobacteria. Lack of enrichment for δ15N in BFT larvae compared to zooplankton implies an alternative grazing pathway from the traditional food chain of phytoplankton—zooplankton—larval fish. Results provide insight for a comparative characterization of the trophic pathways variability of the two main spawning grounds for BFT larvae. PMID:26225849

Sprecies profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic): Bluefish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pottern, G.B.; Huish, M.T.; Kerby, J.H.

1989-02-01

Species profiles are literature summaries of the taxonomy, morphology, distribution, life history, and environmental requirements of coastal fishes and invertebrates within a specified range. They are written to assist in environmental impact assessment and decision making by coastal planners and developers. Bluefish are the most important recreational fish in the United States, especially in the mid-Atlantic region. The commercial catch is smaller but has increased during recent years. One population spawns offshore during spring from northern Florida to North Carolina, and these young migrate into mid-Atlantic coastal waters to spend their summer and fall. A second population spawns offshore duringmore » summer from North Carolina to Massachusetts, but most of these young remain offshore for the remainder of the season. In late fall, young and adults of both populations migrate south until the following spring. Bluefish are migratory, opportunistic, pelagic predators throughout life, and their seasonal abundance may have profound community structuring effects. Schools of juvenile bluefish may be important forage for many pelagic predators, including adults of their own species. Photoperiod apparently triggers long-range migration, and temperature serves as a proximal cue to short-range migration. Bluefish are sensitive to bacterial infection in polluted water and have little tolerance for low oxygen conditions. 55 refs., 6 figs., 3 tabs.« less

Reproduction and mating behavior of the atlantic flyingfish, Cheilopogon melanurus (Exocoetidae), off North Carolina

USGS Publications Warehouse

Casazza, Tara L.; Ross, Steve W.; Necaise, Ann Marie; Sulak, Kenneth J.

2005-01-01

The reproductive biology of Cheilopogon melanurus (Valenciennes, 1847) was examined off North Carolina during the summers of 1991–1992 and 1999–2003. Specimens were collected using a small mesh neuston net and dip nets. A spawning event, the first observation of mating behavior for this species, was recorded off Cape Fear, North Carolina, on 19 August 2003. It was considered to be a spawning event due to: 1) unusual coloration of both sexes, 2) unusual swimming behavior of both sexes, and 3) ready release of gametes by both sexes upon capture. The spawning event occurred in the presence of small clumps of floating Sargassum, but the fish did not appear to use the algae. Over all collections, female gonadosomatic indices were highest in June and July, but mature females were collected each month (June, July, and August). The overall female to male sex ratio did not vary significantly from 1:1. Number of ova increased with increasing fish size, but the relationship was not strong. Our data indicate a spawning season of at least June through August off North Carolina due to high female gonadosomatic indices, large egg diameters, presence of egg filaments, presence of spent females in July and August, and presence of small juveniles (≤ 25 mm) in July and August. This is the first report of single pair spawning for this family; other species reportedly spawn in large aggregations.

Effects of emergence time and early social rearing environment on behaviour of Atlantic salmon: consequences for juvenile fitness and smolt migration.

PubMed

Larsen, Martin H; Johnsson, Jörgen I; Winberg, Svante; Wilson, Alexander D M; Hammenstig, David; Thörnqvist, Per-Ove; Midwood, Jonathan D; Aarestrup, Kim; Höglund, Erik

2015-01-01

Consistent individual differences in behaviour have been well documented in a variety of animal taxa, but surprisingly little is known about the fitness and life-history consequences of such individual variation. In wild salmonids, the timing of fry emergence from gravel spawning nests has been suggested to be coupled with individual behavioural traits. Here, we further investigate the link between timing of spawning nest emergence and behaviour of Atlantic salmon (Salmo salar), test effects of social rearing environment on behavioural traits in fish with different emergence times, and assess whether behavioural traits measured in the laboratory predict growth, survival, and migration status in the wild. Atlantic salmon fry were sorted with respect to emergence time from artificial spawning nest into three groups: early, intermediate, and late. These emergence groups were hatchery-reared separately or in co-culture for four months to test effects of social rearing environment on behavioural traits. Twenty fish from each of the six treatment groups were then subjected to three individual-based behavioural tests: basal locomotor activity, boldness, and escape response. Following behavioural characterization, the fish were released into a near-natural experimental stream. Results showed differences in escape behaviour between emergence groups in a net restraining test, but the social rearing environment did not affect individual behavioural expression. Emergence time and social environment had no significant effects on survival, growth, and migration status in the stream, although migration propensity was 1.4 to 1.9 times higher for early emerging individuals that were reared separately. In addition, despite individuals showing considerable variation in behaviour across treatment groups, this was not translated into differences in growth, survival, and migration status. Hence, our study adds to the view that fitness (i.e., growth and survival) and life-history predictions from laboratory measures of behaviour should be made with caution and ideally tested in nature.

78 FR 42653 - Taking of Marine Mammals Incidental to Commercial Fishing Operations; Atlantic Large Whale Take...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-16

... through on their way to their Cape Cod Bay feeding ground. Recent passive acoustic studies analyzing right.... (Southern Point, Great Duck Island) 43[deg]59.36' N. lat., 68[deg]37.95' W. long. (R ``2'' Bell, Roaring...

A resolution expressing the sense of the Senate that, at the 21st Regular Meeting of the International Commission on the Conservation of Atlantic Tunas, the United States should seek to ensure management of the eastern Atlantic and Mediterranean bluefin tuna fishery adheres to the scientific advice provided by the Standing Committee on Research and Statistics and has a high probability of achieving the established rebuilding target, pursue strengthened protections for spawning bluefin populations in the Mediterranean Sea to facilitate the recovery of the Atlantic bluefin tuna, pursue imposition of more stringent measures to ensure compliance by all Members with the International Commission for the Conservation of Atlantic Tunas' conservation and management recommendations for Atlantic bluefin tuna and other species, and ensure that United States' quotas of tuna and swordfish are not reallocated to other nations, and for other purposes.

THOMAS, 111th Congress

Sen. Snowe, Olympia J. [R-ME

2009-11-09

Senate - 11/09/2009 Submitted in the Senate, considered, and agreed to without amendment and with a preamble by Unanimous Consent. (All Actions) Tracker: This bill has the status Agreed to in SenateHere are the steps for Status of Legislation:

Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population

PubMed Central

Stiasny, Martina H.; Mittermayer, Felix H.; Sswat, Michael; Voss, Rüdiger; Jutfelt, Fredrik; Chierici, Melissa; Puvanendran, Velmurugu; Mortensen, Atle; Reusch, Thorsten B. H.; Clemmesen, Catriona

2016-01-01

How fisheries will be impacted by climate change is far from understood. While some fish populations may be able to escape global warming via range shifts, they cannot escape ocean acidification (OA), an inevitable consequence of the dissolution of anthropogenic carbon dioxide (CO2) emissions in marine waters. How ocean acidification affects population dynamics of commercially important fish species is critical for adapting management practices of exploited fish populations. Ocean acidification has been shown to impair fish larvae’s sensory abilities, affect the morphology of otoliths, cause tissue damage and cause behavioural changes. Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks. PMID:27551924

Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population.

PubMed

Stiasny, Martina H; Mittermayer, Felix H; Sswat, Michael; Voss, Rüdiger; Jutfelt, Fredrik; Chierici, Melissa; Puvanendran, Velmurugu; Mortensen, Atle; Reusch, Thorsten B H; Clemmesen, Catriona

2016-01-01

How fisheries will be impacted by climate change is far from understood. While some fish populations may be able to escape global warming via range shifts, they cannot escape ocean acidification (OA), an inevitable consequence of the dissolution of anthropogenic carbon dioxide (CO2) emissions in marine waters. How ocean acidification affects population dynamics of commercially important fish species is critical for adapting management practices of exploited fish populations. Ocean acidification has been shown to impair fish larvae's sensory abilities, affect the morphology of otoliths, cause tissue damage and cause behavioural changes. Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks.

Pacific halibut bycatch in Pacific cod fisheries in the Bering Sea: an analysis to evaluate area-time management

NASA Astrophysics Data System (ADS)

Adlerstein, Sara A.; Trumble, Robert J.

1998-03-01

Mortality of discarded Pacific halibut bycatch from Pacific cod fisheries in the Bering Sea leads to significant losses in the halibut setline and in the Pacific cod fisheries. The commercial halibut fishery loses yield because of catch limit reductions to compensate the resource for lost spawning potential and because halibut killed as bycatch will not be available for subsequent harvest, and the cod fisheries may lose harvest if they reach a bycatch mortality limit before reaching allowed catch. In this study, significant differences in Pacific halibut bycatch rates and associated yield losses were found among months and areas of the Bering Sea in the longline and trawl fisheries for Pacific cod in 1990-1992. Bycatch rates were usually highest in late spring and early summer and in areas close to the Unimak Pass. With the exception of 1992, yield loss in the longline fishery was around 1 kg per kg of bycatch mortality, irrespective of where or when bycatch occurred. In the trawl fishery, loss of halibut yield varied from 1 to 4 kg per kg of bycatch mortality. Highest halibut net yield losses per tonne of groundfish harvest usually coincided with highest bycatch rates. When both fisheries operated in one area, trawl bycatch often imposed higher yield losses than longline bycatch, despite lower bycatch rates. Bycatch was affected by the strong 1987 halibut year class. Highest bycatch and yield loss rates occurred in the trawl fishery in 1990 and 1991 when the population was dominated by halibut age-3 and -4, and in the longline fishery in 1992 as fish reached age-5.

Elevated seawater temperature, not pCO2, negatively affects post-spawning adult mussels (Mytilus edulis) under food limitation.

PubMed

Clements, Jeff C; Hicks, Carla; Tremblay, Réjan; Comeau, Luc A

2018-01-01

Pre-spawning blue mussels ( Mytilus edulis ) appear sensitive to elevated temperature and robust to elevated p CO 2 ; however, the effects of these stressors soon after investing energy into spawning remain unknown. Furthermore, while studies suggest that elevated p CO 2 affects the byssal attachment strength of Mytilus trossulus from southern latitudes, p CO 2 and temperature impacts on the byssus strength of other species at higher latitudes remain undocumented. In a 90 day laboratory experiment, we exposed post-spawning adult blue mussels ( M. edulis ) from Atlantic Canada to three p CO 2 levels ( p CO 2 ~625, 1295 and 2440 μatm) at two different temperatures (16°C and 22°C) and assessed energetic reserves on Day 90, byssal attachment strength on Days 30 and 60, and condition index and mortality on Days 30, 60 and 90. Results indicated that glycogen content was negatively affected under elevated temperature, but protein, lipid, and overall energy content were unaffected. Reduced glycogen content under elevated temperature was associated with reduced condition index, reduced byssal thread attachment strength, and increased mortality; elevated p CO 2 had no effects. Overall, these results suggest that the glycogen reserves of post-spawning adult M. edulis are sensitive to elevated temperature, and can result in reduced health and byssal attachment strength, leading to increased mortality. These results are similar to those reported for pre-spawning mussels and suggest that post-spawning blue mussels are tolerant to elevated p CO 2 and sensitive to elevated temperature. In contrast to previous studies, however, elevated pCO 2 did not affect byssus strength, suggesting that negative effects of elevated p CO 2 on byssus strength are not universal.

The use of CPR data in fisheries research [review article

NASA Astrophysics Data System (ADS)

Corten, A.; Lindley, J. A.

2003-08-01

The Continuous Plankton Recorder (CPR) survey was initiated partly to contribute to our understanding of the variability of fish stocks and as a potential method for predicting fish distributions from the abundance and composition of the plankton. The latter objective has been superseded by technological developments in fish detection, but the former has been the subject of continuing, and in recent years expanding use of the CPR data. Examples are presented of application of the data to studies on North Sea herring, cod, mackerel, blue whiting and redfish as well as more general plankton studies relevant to fisheries research. Variations in the migration patterns of herring as well as recruitment have been related to abundances and species composition of the plankton in the CPR survey. Extensive use has been made of the CPR data in relation to cod, particularly in the development and testing of the ‘match-mismatch’ hypothesis. Advection of sufficient numbers of Calanus from the core oceanic areas of its distribution into the areas where the cod stocks occur may partly determine the success of those stocks. The analysis of the distribution and abundances of mackerel larvae in the CPR survey have shown contrasting variations between the North Sea and Celtic Sea. The expansion of the horse mackerel fishery in the north-eastern North Sea since 1987 has been related to physical events and a ‘regime shift’ in the plankton, described from CPR data. The oceanic spawning areas of the blue whiting and redfish were highlighted by the expansion of the CPR survey into the north-eastern and north-western Atlantic respectively. These results helped to focus the attention of fisheries scientists on stocks that have subsequently become the targets for commercial exploitation. The results of the CPR survey, particularly those on Calanusfinmarchicus, the phytoplankton standing stock as measured by the CPR colour index, the overall patterns of trends in plankton abundance and distributions of indicator species have been used by fisheries scientists to interpret variations in fish stocks. Generally the CPR data can be used to determine whether changes in the distributions and growth rates of fish have resulted from changes in planktonic food, changes in strength of ocean currents and distribution of water masses and to identify trends in larval abundances. With the tightening regulation of fisheries to reduce overfishing, global climate change and changing anthropogenic inputs into the sea, the unique source of information on unexploited populations in the long-term time series of the CPR survey will be of increasing value to fisheries scientists in the study of natural variability.

Comparative Influence of Ocean Conditions on Yellowfin and Atlantic Bluefin Tuna Catch from Longlines in the Gulf of Mexico

PubMed Central

Teo, Steven L. H.; Block, Barbara A.

2010-01-01

Directed fishing effort for Atlantic bluefin tuna in the Gulf of Mexico (GOM), their primary spawning grounds in the western Atlantic, has been prohibited since the 1980s due to a precipitous decline of the spawning stock biomass. However, pelagic longlines targeted at other species, primarily yellowfin tuna and swordfish, continue to catch Atlantic bluefin tuna in the GOM as bycatch. Spatial and temporal management measures minimizing bluefin tuna bycatch in the GOM will likely become important in rebuilding the western Atlantic bluefin stock. In order to help inform management policy and understand the relative distribution of target and bycatch species in the GOM, we compared the spatiotemporal variability and environmental influences on the catch per unit effort (CPUE) of yellowfin (target) and bluefin tuna (bycatch). Catch and effort data from pelagic longline fisheries observers (1993–2005) and scientific tagging cruises (1998–2002) were coupled with environmental and biological data. Negative binomial models were used to fit the data for both species and Akaike's Information Criterion (corrected for small sample size) was used to determine the best model. Our results indicate that bluefin CPUE had higher spatiotemporal variability as compared to yellowfin CPUE. Bluefin CPUE increased substantially during the breeding months (March-June) and peaked in April and May, while yellowfin CPUE remained relatively high throughout the year. In addition, bluefin CPUE was significantly higher in areas with negative sea surface height anomalies and cooler sea surface temperatures, which are characteristic of mesoscale cyclonic eddies. In contrast, yellowfin CPUE was less sensitive to environmental variability. These differences in seasonal variability and sensitivity to environmental influences suggest that bluefin tuna bycatch in the GOM can be reduced substantially by managing the spatial and temporal distribution of the pelagic longline effort without substantially impacting yellowfin tuna catches. PMID:20526356

Breeding biology of the spotted salamander Ambystoma maculatum (Shaw) in acidic temporary ponds at Cape Cod, USA

USGS Publications Warehouse

Portnoy, J.W.

1990-01-01

The relationship between water chemistry and breeding success of spotted salamanders Ambystoma maculatum (Shaw) was examined in temporary woodland ponds on outer Cape Cod, Massachusetts in 1985 and 1986. Most pond waters were dilute (3median coductivity = 57 umhos cm-1 (1 umhos cm-1 = 0?1 mSm-1)), acidic (median pH = 4?82), and highly colored (median = 140 Pt-Co units). Most acidity was due to abundant organic acids. Salamander survival to hatching was over 80% at 8 of 12 ponds monitored. Complete mortality, preceded by gross abnormalities, was observed only among embryos in the most acidic spawning pond (pH 4?3-4?5) in both years. Embryo transfers between ponds and laboratory studies indicated that reduced survival was due to the interaction of low pH with high tannin-lignin concentration. The use of amphibian embryonic survival to indicate acid rain effects is complicated by multiple habitat parameters and should only be attempted in conjunction with long-term population monitoring.

Histological assessment of organs in sexually mature and post-spawning steelhead trout and insights into iteroparity

USGS Publications Warehouse

Penney, Zachary L.; Moffitt, Christine M.

2014-01-01

Steelhead trout (Oncorhynchus mykiss) are anadromous and iteroparous, but repeat-spawning rates are generally low. Like other anadromous salmonids, steelhead trout fast during freshwater spawning migrations, but little is known about the changes that occur in vital organs and tissues. We hypothesized that fish capable of repeat-spawning would not undergo the same irreversible degeneration and cellular necrosis documented in semelparous salmon. Using Snake River steelhead trout as a model we used histological analysis to assess the cellular architecture in the pyloric stomach, ovary, liver, and spleen in sexually mature and kelt steelhead trout. We observed 38 % of emigrating kelts with food or fecal material in the gastrointestinal tract. Evidence of feeding was more likely in good condition kelts, and feeding was associated with a significant renewal of villi in the pyloric stomach. No vitellogenic oocytes were observed in sections of kelt ovaries, but perinucleolar and early/late stage cortical alveolus oocytes were present suggesting iteroparity was possible. We documented a negative correlation between the quantity of perinucleolar oocytes in ovarian tissues and fork length of kelts suggesting that larger steelhead trout may invest more into a single spawning event. Liver and spleen tissues of both mature and kelt steelhead trout had minimal cellular necroses. Our findings indicate that the physiological processes causing rapid senescence and death in semelparous salmon are not evident in steelhead trout, and recovery begins in fresh water. Future management efforts to increase iteroparity in steelhead trout and Atlantic salmon must consider the physiological processes that influence post-spawning recovery.

An assessment of juvenile Atlantic cod Gadus morhua distribution and growth using diver operated stereo-video surveys.

PubMed

Elliott, S A M; Ahti, P A; Heath, M R; Turrell, W R; Bailey, D M

2016-08-01

Stereo-video scuba transects were conducted during daylight hours from June to September 2013 within a proposed marine protected area (MPA) in the Firth of Clyde, west of Scotland. More juvenile Atlantic cod Gadus morhua of fork length (LF ) range 6-11 cm were observed in substrata containing mixed gravel, including maerl, than in boulder-cobble substrata with high algal cover, or sand with low density seagrass. Community composition was significantly different between substratum types. A decrease in G. morhua abundance was observed over the period of data collection. Over time, mean and variance in G. morhua LF increased, indicating multiple recruitment events. Protecting mixed gravel substrata could be a beneficial management measure to support the survival and recruitment of juvenile G. morhua; other substrata might be important at night given their diel migratory behaviour. Stereo-video cameras provide a useful non-destructive fisheries-independent method to monitor species abundance and length measurements. © 2016 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.

Trace elements in organisms of different trophic groups in the White Sea

NASA Astrophysics Data System (ADS)

Budko, D. F.; Demina, L. L.; Martynova, D. M.; Gorshkova, O. M.

2015-09-01

Concentrations of trace elements (Fe, Mn, Cu, Pb, Ni, Cr, Cd, As, Co, and Se) have been studied in different trophic groups of organisms: primary producers (seston, presented mostly by phytoplankton), primary consumers (mesozooplankton, macrozooplankton, and bivalves), secondary consumers (predatory macrozooplankton and starfish), and consumers of higher trophic levels (fish species), inhabiting the coastal zone of Kandalaksha Bay and the White Sea (Cape Kartesh). The concentrations of elements differ significantly for the size groups of Sagitta elegans (zooplankton) and blue mussel Mytilus edulis, as well as for the bone and muscle tissues of studied fish species, Atlantic cod Gadus morhua marisalbi and Atlantic wolffish Anarhichas lupus. The concentrations of all the studied elements were lower among the primary consumers and producers, but increased again at higher trophic levels, from secondary consumers to tertiary consumers ("mesozooplankton → macrozooplankton Sagitta elegans" and "mussels → starfish"). Ni and Pb tended to decline through the food chains seston→…→cod and mesozooplankton→…→stickleback. Only the concentrations of Fe increased in all the trophic chains along with the increase of the trophic level.

Interannual variability of physical oceanographic characteristics of Gilbert Bay: A marine protected area in Labrador, Canada

NASA Astrophysics Data System (ADS)

Best, Sara; Lundrigan, Sarah; Demirov, Entcho; Wroblewski, Joe

2011-10-01

Gilbert Bay on the southeast coast of Labrador is the site of the first Marine Protected Area (MPA) established in the subarctic coastal zone of eastern Canada. The MPA was created to conserve a genetically distinctive population of Atlantic cod, Gadus morhua. This article presents results from a study of the interannual variability in atmospheric and physical oceanographic characteristics of Gilbert Bay over the period 1949-2006. We describe seasonal and interannual variability of the atmospheric parameters at the sea surface in the bay. The interannual variability of the atmosphere in the Gilbert Bay region is related to the North Atlantic Oscillation (NAO) and a recent warming trend in the local climate of coastal Labrador. The related changes in seawater temperature, salinity and sea-ice thickness in winter are simulated with a one-dimensional water column model, the General Ocean Turbulence Model (GOTM). A warming Gilbert Bay ecosystem would be favorable for cod growth, but reduced sea-ice formation during the winter months increases the danger of traveling across the bay by snowmobile.

78 FR 15338 - Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; Reef Fish Fishery of Puerto Rico...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-11

... (generally female) parrotfish, thereby enhancing spawning biomass and the supply of gametes (especially eggs... St. Croix parrotfish ACL and cannot mitigate for losses of landings due to discarded and not speared... would result in an estimated annual loss of parrotfish landings between 960 lb (435 kg) and 13,920 lb (6...

Whole body-element composition of Atlantic salmon Salmo salar influenced by migration direction and life stage in three distinct populations.

PubMed

Ebel, J D; Leroux, S J; Robertson, M J; Dempson, J B

2016-11-01

Body-element content was measured for three life stages of wild Atlantic salmon Salmo salar from three distinct Newfoundland populations as individuals crossed between freshwater and marine ecosystems. Life stage explained most of the variation in observed body-element concentration whereas river of capture explained very little variation. Element composition of downstream migrating post-spawn adults (i.e. kelts) and juvenile smolts were similar and the composition of these two life stages strongly differed from adults migrating upstream to spawn. Low variation within life stages and across populations suggests that S. salar may exert rheostatic control of their body-element composition. Additionally, observed differences in trace element concentration between adults and other life stages were probably driven by the high carbon concentration in adults because abundant elements, such as carbon, can strongly influence the observed concentrations of less abundant elements. Thus, understanding variation among individuals in trace elements composition requires the measurement of more abundant elements. Changes in element concentration with ontogeny have important consequences the role of fishes in ecosystem nutrient cycling and should receive further attention. © 2016 The Fisheries Society of the British Isles.

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, S.G.; Van Den Avyle, M.J.

1989-08-01

Species profiles are literature summaries of the life history, distribution and environmental requirements of coastal fishes and invertebrates. Profiles are prepared to assist with environmental impact assessment. The Atlantic menhaden (Brevoortia tyrannus) is an important commercial fish along the Atlantic coast. In the South Atlantic Region, Atlantic menhaden spawn during winter in continental shelf waters. Adults then move inshore and northward in spring; some move into estuaries as far as the brackish-freshwater boundary. Atlantic menhaden larvae in the South Atlantic Region enter estuaries after 1 to 3 months at sea. Young fish move into the shallow regions of estuaries andmore » seem to prefer vegetated marsh habitats. Atlantic menhaden are size-selective plankton feeders as larvae, and filter feeders as juveniles and adults. Due to their large population size, individual growth rates, and seasonal movements, Atlantic menhaden annually consume and redistribute large amounts of energy and materials. They are also important prey for large game fishes such as bluefish (Pomatomus saltatrix), striped bass (Morone saxatilis), and bluefin tuna (Thunnus thynnus). The Atlantic menhaden is associated with estuarine and nearshore systems during all phases of its life cycle. Young menhaden require these food-rich habitats to survive and grown. Destruction of estuarine wetlands has decreased nursery habitat available to Atlantic menhaden and other estuarine wetlands has decreased nursery habitat available to Atlantic menhaden and other estuarine-dependent species. 115 refs., 2 figs., 2 tabs.« less

Gastrointestinal microbial community changes in Atlantic cod (Gadus morhua) exposed to crude oil.

PubMed

Bagi, Andrea; Riiser, Even Sannes; Molland, Hilde Steine; Star, Bastiaan; Haverkamp, Thomas H A; Sydnes, Magne Olav; Pampanin, Daniela Maria

2018-04-02

The expansion of offshore oil exploration increases the risk of marine species being exposed to oil pollution in currently pristine areas. The adverse effects of oil exposure through toxic properties of polycyclic aromatic hydrocarbons (PAHs) have been well studied in Atlantic cod (Gadus morhua). Nevertheless, the fate of conjugated metabolites in the intestinal tract and their effect on the diversity of intestinal microbial community in fish is less understood. Here, we investigated the intestinal microbial community composition of Atlantic cod after 28 days of exposure to crude oil (concentration range 0.0-0.1 mg/L). Analysis of PAH metabolites in bile samples confirmed that uptake and biotransformation of oil compounds occurred as a result of the exposure. Various evidence for altered microbial communities was found in fish exposed to high (0.1 mg/L) and medium (0.05 mg/L) concentrations of oil when compared to fish exposed to low oil concentration (0.01 mg/L) or no oil (control). First, altered banding patterns were observed on denaturing gradient gel electrophoresis for samples pooled from each treatment group. Secondly, based on 16S rRNA sequences, higher levels of oil exposure were associated with a loss of overall diversity of the gut microbial communities. Furthermore, 8 operational taxonomic units (OTUs) were found to have significantly different relative abundances in samples from fishes exposed to high and medium oil concentrations when compared to samples from the control group and low oil concentration. Among these, only one OTU, a Deferribacterales, had increased relative abundance in samples from fish exposed to high oil concentration. The results presented herein contribute to a better understanding of the effects of oil contamination on the gut microbial community changes in fish and highlight the importance of further studies into the area. Our findings suggest that increased relative abundance of bacteria belonging to the order Deferribacterales may be indicative of exposure to oil at concentrations higher than 0.05 mg/L.

The importance of genetic verification for determination of Atlantic salmon in north Pacific waters

USGS Publications Warehouse

Nielsen, J.L.; Williams, I.; Sage, G.K.; Zimmerman, C.E.

2003-01-01

Genetic analyses of two unknown but putative Atlantic salmon Salmo salar captured in the Copper River drainage, Alaska, demonstrated the need for validation of morphologically unusual fishes. Mitochondrial DNA sequences (control region and cytochrome b) and data from two nuclear genes [first internal transcribed spacer (ITS-1) sequence and growth hormone (GH1) amplification product] indicated that the fish caught in fresh water on the Martin River was a coho salmon Oncorhynchus kisutch, while the other fish caught in the intertidal zone of the Copper River delta near Grass Island was an Atlantic salmon. Determination of unusual or cryptic fish based on limited physical characteristics and expected seasonal spawning run timing will add to the controversy over farmed Atlantic salmon and their potential effects on native Pacific species. It is clear that determination of all putative collections of Atlantic salmon found in Pacific waters requires validation. Due to uncertainty of fish identification in the field using plastic morphometric characters, it is recommended that genetic analyses be part of the validation process. ?? 2003 The Fisheries Society of the British Isles.

Spatially-Resolved Influence of Temperature and Salinity on Stock and Recruitment Variability of Commercially Important Fishes in the North Sea

PubMed Central

Akimova, Anna; Núñez-Riboni, Ismael; Kempf, Alexander; Taylor, Marc H.

2016-01-01

Understanding of the processes affecting recruitment of commercially important fish species is one of the major challenges in fisheries science. Towards this aim, we investigated the relation between North Sea hydrography (temperature and salinity) and fish stock variables (recruitment, spawning stock biomass and pre-recruitment survival index) for 9 commercially important fishes using spatially-resolved cross-correlation analysis. We used high-resolution (0.2° × 0.2°) hydrographic data fields matching the maximal temporal extent of the fish population assessments (1948–2013). Our approach allowed for the identification of regions in the North Sea where environmental variables seem to be more influential on the fish stocks, as well as the regions of a lesser or nil influence. Our results confirmed previously demonstrated negative correlations between temperature and recruitment of cod and plaice and identified regions of the strongest correlations (German Bight for plaice and north-western North Sea for cod). We also revealed a positive correlation between herring spawning stock biomass and temperature in the Orkney-Shetland area, as well as a negative correlation between sole pre-recruitment survival index and temperature in the German Bight. A strong positive correlation between sprat stock variables and salinity in the central North Sea was also found. To our knowledge the results concerning correlations between North Sea hydrography and stocks’ dynamics of herring, sole and sprat are novel. The new information about spatial distribution of the correlation provides an additional help to identify mechanisms underlying these correlations. As an illustration of the utility of these results for fishery management, an example is provided that incorporates the identified environmental covariates in stock-recruitment models. PMID:27584155

The role of sea surface circulation and hydrographic processes in anchovy spawning and larvae distribution in the Strait of Sicily (Central Mediterranean).

NASA Astrophysics Data System (ADS)

Falcini, Federico; Palatella, Luigi; Cuttitta, Angela; Bignami, Francesco; Patti, Bernardo; Santoleri, Rosalia; Fiorentino, Fabio

2014-05-01

The European Anchovy (Engraulis encrasicolus, Linnaeus, 1758) is one of the most important resources of the Mediterranean Sea. Despite its abundance and relevance, the anchovy population off the Mediterranean coasts exhibits a patchy distribution. Moreover, its biology and the influence of environment on its variability is poorly known. We here use data from ichthyoplankton-surveys carried out during the peak spawning season in order to analyze abundance and age of anchovy larvae in the Strait of Sicily, with respect to sea surface dynamic and hydrographic parameter patterns. The Strait of Sicily dynamics is characterized by upwelling regions, fronts, vortices, and filaments, with a consequent complexity in the spatial distribution of oceanographic parameters and anchovy larvae. To investigate the role of mesoscale features and oceanographic environment on the latter, anchovy larvae observations were paired to remote sensing data (such as sea surface temperature, chlorophyll, primary production, surface wind speed as well as light attenuation, absorption, and particle backscattering coefficients) and Lagrangian and Eulerian numerical simulations results for ocean currents and larval transport. The subsequent analysis shows and quantifies how the Atlantic Ionian Stream (AIS, a meandering current of Atlantic origin) path and variability, as well as the upwelling-induced south Sicilian coastal current, have consequences for anchovy spawning and larvae distribution. These currents transport anchovy larvae towards the Sicilian coast's south-eastern tip, where larvae are then retained in a frontal structure. However, significant cross-shore transport events due to relatively cold filament-like baroclinic instabilities generated by wind-induced coastal upwelling were also observed. Finally, the larval age distribution qualitatively agrees well with this transport pattern.

The effect of catch-and-release angling at high water temperatures on behaviour and survival of Atlantic salmon Salmo salar during spawning migration.

PubMed

Havn, T B; Uglem, I; Solem, Ø; Cooke, S J; Whoriskey, F G; Thorstad, E B

2015-08-01

In this study, behaviour and survival following catch-and-release (C&R) angling was investigated in wild Atlantic salmon Salmo salar (n = 75) angled on sport fishing gear in the River Otra in southern Norway at water temperatures of 16.3-21.1 °C. Salmo salar were tagged externally with radio transmitters and immediately released back into the river to simulate a realistic C&R situation. The majority of S. salar (91%) survived C&R. Most S. salar that were present in the River Otra during the spawning period 3-4 months later were located at known spawning grounds. Downstream movements (median furthest position: 0.5 km, range: 0.1-11.0 km) during the first 4 days after release were recorded for 72% of S. salar, presumably stress-induced fallback associated with C&R. Individuals that fell back spent a median of 15 days before commencing their first upstream movement after release, and 34 days before they returned to or were located above their release site. Mortality appeared to be somewhat elevated at the higher end of the temperature range (14% at 18-21 °C), although sample sizes were low. In conclusion, C&R at water temperatures up to 18 °C had small behavioural consequences and was associated with low mortality (7%). Nevertheless, low levels of mortality occur due to C&R angling and these losses should be accounted for by management authorities in rivers where C&R is practised. Refinement of best practices for C&R may help to reduce mortality, particularly at warmer temperatures. © 2015 The Fisheries Society of the British Isles.

Natural selection constrains personality and brain gene expression differences in Atlantic salmon (Salmo salar).

PubMed

Thörnqvist, Per-Ove; Höglund, Erik; Winberg, Svante

2015-04-01

In stream-spawning salmonid fishes there is a considerable variation in the timing of when fry leave the spawning nests and establish a feeding territory. The timing of emergence from spawning nests appears to be related to behavioural and physiological traits, e.g. early emerging fish are bolder and more aggressive. In the present study, emerging Atlantic salmon (Salmo salar L.) alevins were sorted into three fractions: early, intermediate and late emerging. At the parr stage, behaviour, stress responses, hindbrain monoaminergic activity and forebrain gene expression were explored in fish from the early and late emerging fractions (first and last 25%). The results show that when subjected to confinement stress, fish from the late emerging fraction respond with a larger activation of the brain serotonergic system than fish from the early fraction. Similarly, in late emerging fish, stress resulted in elevated expression of mRNA coding for serotonin 1A receptors (5-HT1A), GABA-A receptor-associated protein and ependymin, effects not observed in fish from the early emerging fraction. Moreover, fish from the early emerging fraction displayed bolder behaviour than their late emerging littermates. Taken together, these results suggest that time of emergence, boldness and aggression are linked to each other, forming a behavioural syndrome in juvenile salmon. Differences in brain gene expression between early and late emerging salmon add further support to a relationship between stress coping style and timing of emergence. However, early and late emerging salmon do not appear to differ in hypothalamus-pituitary-interrenal (HPI) axis reactivity, another characteristic of divergent stress coping styles. © 2015. Published by The Company of Biologists Ltd.

Climate warming causes life-history evolution in a model for Atlantic cod (Gadus morhua).

PubMed

Holt, Rebecca E; Jørgensen, Christian

2014-01-01

Climate change influences the marine environment, with ocean warming being the foremost driving factor governing changes in the physiology and ecology of fish. At the individual level, increasing temperature influences bioenergetics and numerous physiological and life-history processes, which have consequences for the population level and beyond. We provide a state-dependent energy allocation model that predicts temperature-induced adaptations for life histories and behaviour for the North-East Arctic stock (NEA) of Atlantic cod (Gadus morhua) in response to climate warming. The key constraint is temperature-dependent respiratory physiology, and the model includes a number of trade-offs that reflect key physiological and ecological processes. Dynamic programming is used to find an evolutionarily optimal strategy of foraging and energy allocation that maximizes expected lifetime reproductive output given constraints from physiology and ecology. The optimal strategy is then simulated in a population, where survival, foraging behaviour, growth, maturation and reproduction emerge. Using current forcing, the model reproduces patterns of growth, size-at-age, maturation, gonad production and natural mortality for NEA cod. The predicted climate responses are positive for this stock; under a 2°C warming, the model predicted increased growth rates and a larger asymptotic size. Maturation age was unaffected, but gonad weight was predicted to more than double. Predictions for a wider range of temperatures, from 2 to 7°C, show that temperature responses were gradual; fish were predicted to grow faster and increase reproductive investment at higher temperatures. An emergent pattern of higher risk acceptance and increased foraging behaviour was also predicted. Our results provide important insight into the effects of climate warming on NEA cod by revealing the underlying mechanisms and drivers of change. We show how temperature-induced adaptations of behaviour and several life-history traits are not only mediated by physiology but also by trade-offs with survival, which has consequences for conservation physiology.

Copepods enhance nutritional status, growth and development in Atlantic cod (Gadus morhua L.) larvae — can we identify the underlying factors?

PubMed Central

van der Meeren, Terje; Rønnestad, Ivar; Mangor-Jensen, Anders; Galloway, Trina F.; Kjørsvik, Elin; Hamre, Kristin

2015-01-01

The current commercial production protocols for Atlantic cod depend on enriched rotifers and Artemia during first-feeding, but development and growth remain inferior to fish fed natural zooplankton. Two experiments were conducted in order to identify the underlying factors for this phenomenon. In the first experiment (Exp-1), groups of cod larvae were fed either (a) natural zooplankton, mainly copepods, increasing the size of prey as the larvae grew or (b) enriched rotifers followed by Artemia (the intensive group). In the second experiment (Exp-2), two groups of larvae were fed as in Exp-1, while a third group was fed copepod nauplii (approximately the size of rotifers) throughout the larval stage. In both experiments, growth was not significantly different between the groups during the first three weeks after hatching, but from the last part of the rotifer feeding period and onwards, the growth of the larvae fed copepods was higher than that of the intensive group. In Exp-2, the growth was similar between the two copepod groups during the expeimental period, indicating that nutrient composition, not prey size caused the better growth on copepods. Analyses of the prey showed that total fatty acid composition and the ratio of phospholipids to total lipids was slightly different in the prey organisms, and that protein, taurine, astaxanthin and zinc were lower on a dry weight basis in rotifers than in copepods. Other measured nutrients as DHA, all analysed vitamins, manganese, copper and selenium were similar or higher in the rotifers. When compared to the present knowledge on nutrient requirements, protein and taurine appeared to be the most likely limiting nutrients for growth in cod larvae fed rotifers and Artemia. Larvae fed rotifers/Artemia had a higher whole body lipid content than larvae fed copepods at the end of the experiment (stage 5) after the fish had been fed the same formulated diet for approximately 2 weeks. PMID:26038712

Climate warming causes life-history evolution in a model for Atlantic cod (Gadus morhua)

PubMed Central

Holt, Rebecca E.; Jørgensen, Christian

2014-01-01

Climate change influences the marine environment, with ocean warming being the foremost driving factor governing changes in the physiology and ecology of fish. At the individual level, increasing temperature influences bioenergetics and numerous physiological and life-history processes, which have consequences for the population level and beyond. We provide a state-dependent energy allocation model that predicts temperature-induced adaptations for life histories and behaviour for the North-East Arctic stock (NEA) of Atlantic cod (Gadus morhua) in response to climate warming. The key constraint is temperature-dependent respiratory physiology, and the model includes a number of trade-offs that reflect key physiological and ecological processes. Dynamic programming is used to find an evolutionarily optimal strategy of foraging and energy allocation that maximizes expected lifetime reproductive output given constraints from physiology and ecology. The optimal strategy is then simulated in a population, where survival, foraging behaviour, growth, maturation and reproduction emerge. Using current forcing, the model reproduces patterns of growth, size-at-age, maturation, gonad production and natural mortality for NEA cod. The predicted climate responses are positive for this stock; under a 2°C warming, the model predicted increased growth rates and a larger asymptotic size. Maturation age was unaffected, but gonad weight was predicted to more than double. Predictions for a wider range of temperatures, from 2 to 7°C, show that temperature responses were gradual; fish were predicted to grow faster and increase reproductive investment at higher temperatures. An emergent pattern of higher risk acceptance and increased foraging behaviour was also predicted. Our results provide important insight into the effects of climate warming on NEA cod by revealing the underlying mechanisms and drivers of change. We show how temperature-induced adaptations of behaviour and several life-history traits are not only mediated by physiology but also by trade-offs with survival, which has consequences for conservation physiology. PMID:27293671

Atlantic wolf-fish Anarhichas lupus population diversity: growth and maturation.

PubMed

Gunnarsson, Á

2014-02-01

Biological data from 1125 female Atlantic wolf-fish Anarhichas lupus were collected during 2002-2006 at their main spawning and fishing grounds in Iceland. The results demonstrated substantial annual variation in growth and maturity of female A. lupus. The fast growing females mature earlier than the slow growing ones. In addition, females mature at a larger size and greater age in warmer temperatures than colder ones. There was a strong negative relationship between temperature and growth, which may indicate that the sea temperature west of Iceland has risen above the optimum for growth of female A. lupus and thereby reduced the reproductive potential of the species. © 2014 The Fisheries Society of the British Isles.

The role of extracellular matrix components in pin bone attachments during storage-a comparison between farmed Atlantic salmon (Salmo salar) and cod (Gadus morhua L.).

PubMed

Rønning, Sissel B; Østbye, Tone-Kari; Krasnov, Aleksei; Vuong, Tram T; Veiseth-Kent, Eva; Kolset, Svein O; Pedersen, Mona E

2017-04-01

Pin bones represent a major problem for processing and quality of fish products. Development of methods of removal requires better knowledge of the pin bones' attachment to the muscle and structures involved in the breakdown during loosening. In this study, pin bones from cod and salmon were dissected from fish fillets after slaughter or storage on ice for 5 days, and thereafter analysed with molecular methods, which revealed major differences between these species before and after storage. The connective tissue (CT) attaches the pin bone to the muscle in cod, while the pin bones in salmon are embedded in adipose tissue. Collagens, elastin, lectin-binding proteins and glycosaminoglycans (GAGs) are all components of the attachment site, and this differ between salmon and cod, resulting in a CT in cod that is more resistant to enzymatic degradation compared to the CT in salmon. Structural differences are reflected in the composition of transcriptome. Microarray analysis comparing the attachment sites of the pin bones with a reference muscle sample showed limited differences in salmon. In cod, on the other hand, the variances were substantial, and the gene expression profiles suggested difference in myofibre structure, metabolism and cell processes between the pin bone attachment site and the reference muscle. Degradation of the connective tissue occurs closest to the pin bones and not in the neighbouring tissue, which was shown using light microscopy. This study shows that the attachment of the pin bones in cod and salmon is different; therefore, the development of methods for removal should be tailored to each individual species.

Environmental genotoxicity and cytotoxicity in flounder (Platichthys flesus), herring (Clupea harengus) and Atlantic cod (Gadus morhua) from chemical munitions dumping zones in the southern Baltic Sea.

PubMed

Baršienė, Janina; Butrimavičienė, Laura; Grygiel, Wlodzimierz; Lang, Thomas; Michailovas, Aleksandras; Jackūnas, Tomas

2014-05-01

The data on environmental genotoxicity and cytotoxicity levels as well as on genotoxicity risk in flounder (Platichthys flesus), herring (Clupea harengus) and cod (Gadus morhua) collected in 2010-2012 at 42 stations located in chemical munitions dumping areas of the southern Baltic Sea are presented. The frequency of micronuclei, nuclear buds and nucleoplasmic bridges in erythrocytes was used as genotoxicity endpoint and the induction of fragmented-apoptotic, bi-nucleated and 8-shaped erythrocytes as cytotoxicity endpoint. The most significantly increased geno-cytotoxicity levels were determined in fish collected near known chemical munitions dumpsites. Extremely high genotoxicity risk for flounder were identified at 21 out of 24 stations, for herring at 29 out of 31 and for cod at 5 out of 10 stations studied. The reference level of genotoxicity was not recorded at any of the stations revealing that in the sampling area fish were affected generally. Copyright © 2013 Elsevier Ltd. All rights reserved.

Geologic history of Cape Cod, Massachusetts

USGS Publications Warehouse

,

1976-01-01

Cape Cod, a sandy peninsula built mostly during the Ice Age, juts into the Atlantic Ocean like a crooked arm. Because of its exposed location, Cape Cod was visited by many early explorers. Although clear-cut evidence is lacking, the Vikings may have sighted this land about 1,000 years ago. It was visited by Samuel de Champlain in 1605, and his detailed descriptions and charts have helped present-day scientists to determine the rate of growth of Nauset Beach marsh and Nauset spit. Bartholomew Gosnold, a lesser known explorer, settled for a short time on the Elizabeth Islands to the southwest and gave Cape Cod its name in 1602. The Pilgrims first landed in America on the tip of Lower Cape Cod after they were turned back from their more southerly destination by shoals between Cape Cod and Nantucket Island. On Cape Cod they found potable water and food and had their first fight with the natives. The Pilgrims, however, decided that this land was too isolated, too exposed, and too sandy to support them, and they sailed across Cape Cod Bay to establish Plymouth. These features remain today. Small villages are separated by large areas of forest, dune, beach, and marsh. This unspoiled natural beauty makes Cape Cod one of the most favored vacation areas for the people living in the thickly settled Northeastern States. Cape Cod is of particular interest to geologists because it was formed by glaciers very recently in terms of geologic time. During the Great Ice Age, (the Pleistocene Epoch which began 2 to 3 million years ago), glaciers advanced from the north into the temperate regions of the Earth. Glacial ice covered the land at least four times. Each advance was accompanied by a worldwide lowering of sea level because the source of the ice was water from the seas. When the glaciers melted, the climate and sea level were probably much like they are today. In fact, some scientists believe that the Earth is presently between glacial episodes and that ice once again will advance across the land.

Single and mixture effects of aquatic micropollutants studied in precision-cut liver slices of Atlantic cod (Gadus morhua).

PubMed

Bizarro, Cristina; Eide, Marta; Hitchcock, Daniel J; Goksøyr, Anders; Ortiz-Zarragoitia, Maren

2016-08-01

The low concentrations of most contaminants in the aquatic environment individually may not affect the normal function of the organisms on their own. However, when combined, complex mixtures may provoke unexpected effects even at low amounts. Selected aquatic micropollutants such as chlorpyrifos, bis-(2-ethylhexyl)-phthalate (DEHP), perfluorooctanoic acid (PFOA) and 17α-ethinylestradiol (EE2) were tested singly and in mixtures at nM to μM concentrations using precision-cut liver slices (PCLS) of Atlantic cod (Gadus morhua). Fish liver is a target organ for contaminants due to its crucial role in detoxification processes. In order to understand the effects on distinct key liver metabolic pathways, transcription levels of various genes were measured, including cyp1a1 and cyp3a, involved in the metabolism of organic compounds, including toxic ones, and the catabolism of bile acids and steroid hormones; cyp7a1, fabp and hmg-CoA, involved in lipid and cholesterol homeostasis; cyp24a1, involved in vitamin D metabolism; and vtg, a key gene in xenoestrogenic response. Only EE2 had significant effects on gene expression in cod liver slices when exposed singly at the concentrations tested. However, when exposed in combinations, effects not detected in single exposure conditions arose, suggesting complex interactions between studied pollutants that could not be predicted from the results of individual exposure scenarios. Thus, the present work highlights the importance of assessing mixtures when describing the toxic effects of micropollutants to fish liver metabolism. Copyright © 2016 Elsevier B.V. All rights reserved.

The role of a dominant predator in shaping biodiversity over space and time in a marine ecosystem.

PubMed

Ellingsen, Kari E; Anderson, Marti J; Shackell, Nancy L; Tveraa, Torkild; Yoccoz, Nigel G; Frank, Kenneth T

2015-09-01

1. Exploitation of living marine resources has resulted in major changes to populations of targeted species and functional groups of large-bodied species in the ocean. However, the effects of overfishing and collapse of large top predators on the broad-scale biodiversity of oceanic ecosystems remain largely unexplored. 2. Populations of the Atlantic cod (Gadus morhua) were overfished and several collapsed in the early 1990s across Atlantic Canada, providing a unique opportunity to study potential ecosystem-level effects of the reduction of a dominant predator on fish biodiversity, and to identify how such effects might interact with other environmental factors, such as changes in climate, over time. 3. We combined causal modelling with model selection and multimodel inference to analyse 41 years of fishery-independent survey data (1970-2010) and quantify ecosystem-level effects of overfishing and climate variation on the biodiversity of fishes across a broad area (172 000 km(2) ) of the Scotian Shelf. 4. We found that alpha and beta diversity increased with decreases in cod occurrence; fish communities were less homogeneous and more variable in systems where cod no longer dominated. These effects were most pronounced in the colder north-eastern parts of the Scotian Shelf. 5. Our results provide strong evidence that intensive harvesting (and collapse) of marine apex predators can have large impacts on biodiversity, with far-reaching consequences for ecological stability across an entire ecosystem. © 2015 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

The parasitic copepod Lernaeocera branchialis negatively affects cardiorespiratory function in Gadus morhua.

PubMed

Behrens, J W; Seth, H; Axelsson, M; Buchmann, K

2014-05-01

The parasitic copepod Lernaeocera branchialis had a negative effect on cardiorespiratory function in Atlantic cod Gadus morhua such that it caused pronounced cardiac dysfunction with irregular rhythm and reduced stroke amplitude compared with uninfected fish. In addition, parasite infection depressed the postprandial cardiac output and oxygen consumption. © 2014 The Fisheries Society of the British Isles.

Impacts of regular and random noise on the behaviour, growth and development of larval Atlantic cod (Gadus morhua)

PubMed Central

Nedelec, Sophie L.; Simpson, Stephen D.; Morley, Erica L.; Nedelec, Brendan; Radford, Andrew N.

2015-01-01

Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod (Gadus morhua). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width–length ratios. Larvae with lower body width–length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures. PMID:26468248

Impacts of regular and random noise on the behaviour, growth and development of larval Atlantic cod (Gadus morhua).

PubMed

Nedelec, Sophie L; Simpson, Stephen D; Morley, Erica L; Nedelec, Brendan; Radford, Andrew N

2015-10-22

Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod (Gadus morhua). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width-length ratios. Larvae with lower body width-length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures. © 2015 The Authors.

Goosefish Lophius americanus fecundity and spawning frequency, with implications for population reproductive potential.

PubMed

McBride, R S; Johnson, A K; Lindsay, E K; Walsh, H J; Richards, R A

2017-05-01

To improve knowledge of goosefish Lophius americanus' reproductive biology, females were collected during 2009-2012 from the Mid-Atlantic Bight shelf region of the U.S. east coast. Batch fecundity increased with total length (L T ), from 229 100 to 2 243 300 mature oocytes per female (L T range: 55·5-112 cm; n = 54). This estimate of fecundity at L T is lower than one derived from a sample collected during 1982-1985. Examination of whole oocyte diameters in different months indicated that L. americanus is a serial spawner, releasing more than one egg veil per spawning season, as suspected or observed for other Lophius species. Seasonality of spawning was evident from whole oocytes and gonad histology, and from larval fish surveys spanning the U.S. north-east shelf, and confirmed a protracted (c. 6 months) spawning period. Peak spawning activity progressed northward from spring to autumn. The population-level implications of these results were explored by estimating population reproductive potential (P RP ), which considered the value of both current and future per capita reproduction using decade-specific age structure and fecundity at length. P RP is now more than 50% lower compared with the historical period (1982-1985), a result of the lower proportions of large females and reduced fecundity across all sizes. Mechanisms that could explain this loss of stock productivity are fishing-induced size-age truncation or regime shifts in egg production caused by changes in energy density of common forage species. © 2017 The Fisheries Society of the British Isles.

Diversity and genetic structure of white mullet populations in the Gulf of Mexico analyzed by microsatellite markers

NASA Astrophysics Data System (ADS)

Pacheco-Almanzar, Eloisa; Ramírez-Saad, Hugo; Velázquez-Aragón, José A.; Serrato, Alejandra; Ibáñez, Ana L.

2017-11-01

The white mullet (Mugil curema) is a species of wide geographical distribution on both coasts of America, inhabiting coastal lagoons, estuaries and rivers. Adults form schools and migrate into the open sea to spawn, where both eggs and hatchlings are subject to transport by surface currents. In northern Gulf of Mexico, under the influence of temperate waters M. curema has a single spawning in spring and summer, while in southern Gulf of Mexico, with warmer environments, spawnings are in summer and winter. These asynchronous spawning may point to the existence of different populations, while the planktonic mobility of eggs and larvae open the possibility that the putative populations mix together. Aiming to address whether there are different genetic groups of M. curema, ten coastal sampling sites along the Gulf of Mexico plus one site in the NE Atlantic coast were selected. A total of 363 individuals comprising all sampling sites were analyzed by means of microsatellites. 10 loci were tested and the number of alleles per locus varied between 7 and 19. All loci showed significant genetic differentiation (FST = 0.287), while Evanno test resulted in a K = 3 value, suggesting that three is the most probable number of M. curema groups in the studied area. This grouping is possibly associated with spawning time, contrasting oceanographic conditions in the north, center, and south of the Gulf of Mexico, as well as ecological and geomorphologic differences between lagoon environments; giving as consequence variations in the history of life of M. curema populations.

Parasites as biological tags of marine, freshwater and anadromous fishes in North America from the Tropics to the Arctic.

PubMed

Marcogliese, David J; Jacobson, Kym C

2015-01-01

Parasites have been considered as natural biological tags of marine fish populations in North America for almost 75 years. In the Northwest Atlantic, the most studied species include Atlantic cod (Gadus morhua), Atlantic herring (Clupea harengus) and the redfishes (Sebastes spp.). In the North Pacific, research has centred primarily on salmonids (Oncorhynchus spp.). However, parasites have been applied as tags for numerous other pelagic and demersal species on both the Atlantic and Pacific coasts. Relatively few studies have been undertaken in the Arctic, and these were designed to discriminate anadromous and resident salmonids (Salvelinus spp.). Although rarely applied in fresh waters, parasites have been used to delineate certain fish stocks within the Great Lakes-St Lawrence River basin. Anisakid nematodes and the copepod Sphyrion lumpi frequently prove useful indicators in the Northwest Atlantic, while myxozoan parasites prove very effective on the coast and open seas of the Pacific Ocean. Relative differences in the ability of parasites to discriminate between fish stocks on the Pacific and Atlantic coasts may be due to oceanographic and bathymetric differences between regions. Molecular techniques used to differentiate populations and species of parasites show promise in future applications in the field.

Adaptive strategies and life history characteristics in a warming climate: salmon in the Arctic?

USGS Publications Warehouse

Nielsen, Jennifer L.; Ruggerone, Gregory T.; Zimmerman, Christian E.

2013-01-01

In the warming Arctic, aquatic habitats are in flux and salmon are exploring their options. Adult Pacific salmon, including sockeye (Oncorhynchus nerka), coho (O. kisutch), Chinook (O. tshawytscha), pink (O. gorbuscha) and chum (O. keta) have been captured throughout the Arctic. Pink and chum salmon are the most common species found in the Arctic today. These species are less dependent on freshwater habitats as juveniles and grow quickly in marine habitats. Putative spawning populations are rare in the North American Arctic and limited to pink salmon in drainages north of Point Hope, Alaska, chum salmon spawning rivers draining to the northwestern Beaufort Sea, and small populations of chum and pink salmon in Canada’s Mackenzie River. Pacific salmon have colonized several large river basins draining to the Kara, Laptev and East Siberian seas in the Russian Arctic. These populations probably developed from hatchery supplementation efforts in the 1960’s. Hundreds of populations of Arctic Atlantic salmon (Salmo salar) are found in Russia, Norway and Finland. Atlantic salmon have extended their range eastward as far as the Kara Sea in central Russian. A small native population of Atlantic salmon is found in Canada’s Ungava Bay. The northern tip of Quebec seems to be an Atlantic salmon migration barrier for other North American stocks. Compatibility between life history requirements and ecological conditions are prerequisite for salmon colonizing Arctic habitats. Broad-scale predictive models of climate change in the Arctic give little information about feedback processes contributing to local conditions, especially in freshwater systems. This paper reviews the recent history of salmon in the Arctic and explores various patterns of climate change that may influence range expansions and future sustainability of salmon in Arctic habitats. A summary of the research needs that will allow informed expectation of further Arctic colonization by salmon is given.

What is left? Macrophyte meadows and Atlantic herring (Clupea harengus) spawning sites in the Greifswalder Bodden, Baltic Sea

NASA Astrophysics Data System (ADS)

Kanstinger, Philipp; Beher, Jutta; Grenzdörffer, Görres; Hammer, Cornelius; Huebert, Klaus B.; Stepputis, Daniel; Peck, Myron A.

2018-02-01

Coastal zones are productive areas of marine ecosystems which are also hotspots of anthropogenic activities causing habitat degradation. In the southwest Baltic Sea, eutrophication is thought to have caused the massive reduction in submerged macrophytes observed in recent decades. Here, we surveyed the submarine vegetation and examined locations of spawning of herring (Clupea harengus) in the Greifswalder Bodden, one of the most important reproductive habitats of the Western Baltic Spring Spawner herring stock (WBSS). This stock deposits eggs onto submerged vegetation and changes in macrophyte coverage are expected to influence the availability of reproductive habitat. Aerial, underwater video tows and SCUBA surveys conducted in spring 2009 revealed that only ∼7% of the lagoon was vegetated. Herring eggs were observed on 12 of 32 SCUBA transects, at depths between 0.2 and 5 m and were attached to a variety of spermatophyte and algae species but not to stones or mussels. A classification tree model indicated that spawning sites were strongly associated with the vegetation cover within a 100- and 500-m radius, implying that herring schools preferentially spawn on dense and large underwater meadows. Only ∼5% of the lagoon now falls into this vegetation category. Despite 20 years of efforts to reduce eutrophication, no increase in macroalgae and spermatophyte vegetation towards the historical level of 90% coverage in the area is apparent.

Coupling survey data with drift model results suggests that local spawning is important for Calanus finmarchicus production in the Barents Sea

NASA Astrophysics Data System (ADS)

Kvile, Kristina Øie; Fiksen, Øyvind; Prokopchuk, Irina; Opdal, Anders Frugård

2017-01-01

The copepod Calanus finmarchicus is an important part of the diet for several large fish stocks feeding in the Atlantic waters of the Barents Sea. Determining the origin of the new generation copepodites present on the Barents Sea shelf in spring can shed light on the importance of local versus imported production of C. finmarchicus biomass in this region. In this study, we couple large-scale spatiotemporal survey data (> 30 years in both Norwegian Sea and Barents Sea areas) with drift trajectories from a hydrodynamic model to back-calculate and map the spatial distribution of C. finmarchicus from copepod to egg, allowing us to identify potential adult spawning areas. Assuming the adult stage emerges from overwintering in the Norwegian Sea, our results suggest that copepodites sampled at the Barents Sea entrance are a mix of locally spawned individuals and long-distance-travellers advected northwards along the Norwegian shelf edge. However, copepodites sampled farther east in the Barents Sea (33°30‧E) are most likely spawned on the Barents Sea shelf, potentially from females that have overwintered locally. Our results support that C. finmarchicus dynamics in the Barents Sea are not, at least in the short-term, solely driven by advection from the Norwegian Sea, but that local production may be more important than commonly believed.

Comparative diets of subyearling Atlantic salmon and subyearling coho salmon in Lake Ontario tributaries

USGS Publications Warehouse

Johnson, James H.; Ringler, Neil H.

2016-01-01

Restoration of Atlantic salmon (Salmo salar) in Lake Ontario could potentially be negatively affected by the presence of non-native salmonids that are naturalized in the basin. Coho salmon (Oncorhynchus kisutch) have been spawning successfully in Lake Ontario tributaries for over 40 years and their juveniles will reside in streams with juvenile Atlantic salmon for one year. This study sought to examine interspecific diet associations between these species, and to compare diets to the composition of the benthos and drift in three Lake Ontario tributaries. Aquatic insects, mainly ephemeropterans and chironomids were the major prey consumed by subyearling Atlantic salmon whereas terrestrial invertebrates made up only 3.7% of the diet. Ephemeropterans and chironomids were the primary aquatic taxa consumed by subyearling coho salmon but, as a group, terrestrial invertebrates (41.8%) were the major prey. In sympatry, Atlantic salmon fed more actively from the benthos whereas the diet of coho salmon was more similar to the drift. The different feeding pattern of each species resulted in low interspecific diet similarity. There is likely little competition between these species for food in Lake Ontario tributaries as juveniles.

Climate variability and marine ecosystem impacts: a North Atlantic perspective

NASA Astrophysics Data System (ADS)

Parsons, L. S.; Lear, W. H.

In recent decades it has been recognized that in the North Atlantic climatic variability has been largely driven by atmospheric forcing related to the North Atlantic Oscillation (NAO). The NAO index began a pronounced decline around 1950 to a low in the 1960s. From 1970 onward the NAO index increased to its most extreme and persistent positive phase during the late 1980s and early 1990s. Changes in the pattern of the NAO have differential impacts on the opposite sides of the North Atlantic and differential impacts in the north and south. The changes in climate resulting from changes in the NAO appear to have had substantial impacts on marine ecosystems, in particular, on fish productivity, with the effects varying from region to region. An examination of several species and stocks, e.g. gadoids, herring and plankton in the Northeast Atlantic and cod and shellfish in the Northwest Atlantic, indicates that there is a link between long-term trends in the NAO and the productivity of various components of the marine ecosystem. While broad trends are evident, the mechanisms are poorly understood. Further research is needed to improve our understanding of how this climate variability affects the productivity of various components of the North Atlantic marine ecosystem.

Molecular identification and transmission studies of X-cell parasites from Atlantic cod Gadus morhua (Gadiformes: Gadidae) and the northern black flounder Pseudopleuronectes obscurus (Pleuronectiformes: Pleuronectidae)

PubMed Central

2011-01-01

Background Epidermal pseudotumours from Hippoglossoides dubius and Acanthogobius flavimanus in Japan and gill lesions in Limanda limanda from the UK have been shown to be caused by phylogenetically related protozoan parasites, known collectively as X-cells. However, the phylogenetic position of the X-cell group is not well supported within any of the existing protozoan phyla and they are currently thought to be members of the Alveolata. Ultrastructural features of X-cells in fish pseudotumours are somewhat limited and no typical environmental stages, such as spores or flagellated cells, have been observed. The life cycles for these parasites have not been demonstrated and it remains unknown how transmission to a new host occurs. In the present study, pseudobranchial pseudotumours from Atlantic cod, Gadus morhua, in Iceland and epidermal pseudotumours from the northern black flounder, Pseudopleuronectes obscurus, in Japan were used in experimental transmission studies to establish whether direct transmission of the parasite is achievable. In addition, X-cells from Atlantic cod were sequenced to confirm whether they are phylogenetically related to other X-cells and epidermal pseudotumours from the northern black flounder were analysed to establish whether the same parasite is responsible for infecting different flatfish species in Japan. Results Phylogenetic analyses of small subunit ribosomal DNA (SSU rDNA) sequence data from Atlantic cod X-cells show that they are a related parasite that occupies a basal position to the clade containing other X-cell parasites. The X-cell parasite causing epidermal pseudotumours in P. obscurus is the same parasite that causes pseudotumours in H. dubius. Direct, fish to fish, transmission of the X-cell parasites used in this study, via oral feeding or injection, was not achieved. Non-amoeboid X-cells are contained within discrete sac-like structures that are loosely attached to epidermal pseudotumours in flatfish; these X-cells are able to tolerate exposure to seawater. A sensitive nested PCR assay was developed for the sub clinical detection of both parasites and to assist in future life cycle studies. PCR revealed that the parasite in P. obscurus was detectable in non-pseudotumourous areas of fish that had pseudotumours present in other areas of the body. Conclusions The inability to successfully transmit both parasites in this study suggests that either host detachment combined with a period of independent development or an alternate host is required to complete the life cycle for X-cell parasites. Phylogenetic analyses of SSU rDNA confirm a monophyletic grouping for all sequenced X-cell parasites, but do not robustly support their placement within any established protist phylum. Analysis of SSU rDNA from X-cells in Japanese flatfish reveals that the same parasite can infect more than one species of fish. PMID:21299903

Thiaminase activity and life history investigations in American Shad in the Columbia river

USGS Publications Warehouse

Wetzel, Lisa A.; Parsley, Michael J; van der Leeuw, Bjorn K.; Larsen, Kimberly A.

2011-01-01

American shad Alosa sapidissima fry were successfully transplanted from the Atlantic to the Pacific coast in 1871 and have subsequently proliferated. The Columbia River population is in the millions, yet few investigations have been conducted to better understand their life history, population dynamics, or potential impacts on other species. In 2007 and 2008 we captured American shad from the Columbia River to assess levels of thiaminase activity and to characterize some aspects of American shad life history. Thiaminase levels in age-0 and adult fish were high and ranged from 4,113-20,874 pmol/g/min. Ages of spawning American shad ranged from 3-7 years and iteroparity was approximately 33-36% in the spawning population. Males were typically younger and smaller and had a higher degree of iteroparity than females

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (South Atlantic): Bluefish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliver, J.D.; Van Den Avyle, M.J.; Bozeman, E.L. Jr.

1989-04-01

Species profiles are literature summaries of the life history, distribution, and environmental requirements of coastal fishes and invertebrates. Profiles are prepared to assist with environmental impact assessment. The bluefish (Pomatomus saltatrix) is a valuable recreational and commercial fish on the Atlantic coast. In the South Atlantic Region the recreational catch exceeds the commercial catch. The bluefish is a migratory pelagic fish that generally travels northward in spring and summer and southward in fall and winter along the Atlantic seaboard. In the South Atlantic Region, spawning occurs primarily during spring waters just shoreward of the Gulf Stream form southern North Carolinamore » to Florida. Most larvae are carried northward by the Gulf Stream and are dispersed over the continental slope of the Middle Atlantic Region. Adult bluefish inhabit nearshore areas in the South Atlantic Region during their southerly migration in fall and winter. Larval bluefish eat mostly copepods, cladocerans, and invertebrate eggs; juveniles eat larger invertebrates and fishes. Adult bluefish eat fishes and seem to prefer schooling coastal species. Bluefish have been reported to avoid areas of low dissolved oxygen. Water turbidity may affect feeding because bluefish rely on vision to locate prey. Environmental disturbances which affect the dissolved oxygen concentration or turbidity of estuarine and nearshore waters may, therefore, affect bluefish distribution and feeding. 40 refs., 4 figs., 2 tabs.« less

A moderate increase in ambient temperature modulates the Atlantic cod (Gadus morhua) spleen transcriptome response to intraperitoneal viral mimic injection

PubMed Central

2012-01-01

Background Atlantic cod (Gadus morhua) reared in sea-cages can experience large variations in temperature, and these have been shown to affect their immune function. We used the new 20K Atlantic cod microarray to investigate how a water temperature change which, simulates that seen in Newfoundland during the spring-summer (i.e. from 10°C to 16°C, 1°C increase every 5 days) impacted the cod spleen transcriptome response to the intraperitoneal injection of a viral mimic (polyriboinosinic polyribocytidylic acid, pIC). Results The temperature regime alone did not cause any significant increases in plasma cortisol levels and only minor changes in spleen gene transcription. However, it had a considerable impact on the fish spleen transcriptome response to pIC [290 and 339 significantly differentially expressed genes between 16°C and 10°C at 6 and 24 hours post-injection (HPI), respectively]. Seventeen microarray-identified transcripts were selected for QPCR validation based on immune-relevant functional annotations. Fifteen of these transcripts (i.e. 88%), including DHX58, STAT1, IRF7, ISG15, RSAD2 and IκBα, were shown by QPCR to be significantly induced by pIC. Conclusions The temperature increase appeared to accelerate the spleen immune transcriptome response to pIC. We found 41 and 999 genes differentially expressed between fish injected with PBS vs. pIC at 10°C and sampled at 6HPI and 24HPI, respectively. In contrast, there were 656 and 246 genes differentially expressed between fish injected with PBS vs. pIC at 16°C and sampled at 6HPI and 24HPI, respectively. Our results indicate that the modulation of mRNA expression of genes belonging to the NF-κB and type I interferon signal transduction pathways may play a role in controlling temperature-induced changes in the spleen’s transcript expression response to pIC. Moreover, interferon effector genes such as ISG15 and RSAD2 were differentially expressed between fish injected with pIC at 10°C vs. 16°C at 6HPI. These results substantially increase our understanding of the genes and molecular pathways involved in the negative impacts of elevated ambient temperature on fish health, and may also be valuable to our understanding of how accelerated global climate change could impact cold-water marine finfish species. PMID:22928584

A moderate increase in ambient temperature modulates the Atlantic cod (Gadus morhua) spleen transcriptome response to intraperitoneal viral mimic injection.

PubMed

Hori, Tiago S; Gamperl, A Kurt; Booman, Marije; Nash, Gordon W; Rise, Matthew L

2012-08-28

Atlantic cod (Gadus morhua) reared in sea-cages can experience large variations in temperature, and these have been shown to affect their immune function. We used the new 20K Atlantic cod microarray to investigate how a water temperature change which, simulates that seen in Newfoundland during the spring-summer (i.e. from 10°C to 16°C, 1°C increase every 5 days) impacted the cod spleen transcriptome response to the intraperitoneal injection of a viral mimic (polyriboinosinic polyribocytidylic acid, pIC). The temperature regime alone did not cause any significant increases in plasma cortisol levels and only minor changes in spleen gene transcription. However, it had a considerable impact on the fish spleen transcriptome response to pIC [290 and 339 significantly differentially expressed genes between 16°C and 10°C at 6 and 24 hours post-injection (HPI), respectively]. Seventeen microarray-identified transcripts were selected for QPCR validation based on immune-relevant functional annotations. Fifteen of these transcripts (i.e. 88%), including DHX58, STAT1, IRF7, ISG15, RSAD2 and IκBα, were shown by QPCR to be significantly induced by pIC. The temperature increase appeared to accelerate the spleen immune transcriptome response to pIC. We found 41 and 999 genes differentially expressed between fish injected with PBS vs. pIC at 10°C and sampled at 6HPI and 24HPI, respectively. In contrast, there were 656 and 246 genes differentially expressed between fish injected with PBS vs. pIC at 16°C and sampled at 6HPI and 24HPI, respectively. Our results indicate that the modulation of mRNA expression of genes belonging to the NF-κB and type I interferon signal transduction pathways may play a role in controlling temperature-induced changes in the spleen's transcript expression response to pIC. Moreover, interferon effector genes such as ISG15 and RSAD2 were differentially expressed between fish injected with pIC at 10°C vs. 16°C at 6HPI. These results substantially increase our understanding of the genes and molecular pathways involved in the negative impacts of elevated ambient temperature on fish health, and may also be valuable to our understanding of how accelerated global climate change could impact cold-water marine finfish species.

50 CFR 622.208 - Minimum mesh size applicable to rock shrimp off Georgia and Florida.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Minimum mesh size applicable to rock... mesh size applicable to rock shrimp off Georgia and Florida. (a) The minimum mesh size for the cod end of a rock shrimp trawl net in the South Atlantic EEZ off Georgia and Florida is 17/8 inches (4.8 cm...

50 CFR 622.208 - Minimum mesh size applicable to rock shrimp off Georgia and Florida.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Minimum mesh size applicable to rock... mesh size applicable to rock shrimp off Georgia and Florida. (a) The minimum mesh size for the cod end of a rock shrimp trawl net in the South Atlantic EEZ off Georgia and Florida is 17/8 inches (4.8 cm...

Food webs and carbon flux in the Barents Sea

NASA Astrophysics Data System (ADS)

Wassmann, Paul; Reigstad, Marit; Haug, Tore; Rudels, Bert; Carroll, Michael L.; Hop, Haakon; Gabrielsen, Geir Wing; Falk-Petersen, Stig; Denisenko, Stanislav G.; Arashkevich, Elena; Slagstad, Dag; Pavlova, Olga

2006-10-01

Within the framework of the physical forcing, we describe and quantify the key ecosystem components and basic food web structure of the Barents Sea. Emphasis is given to the energy flow through the ecosystem from an end-to-end perspective, i.e. from bacteria, through phytoplankton and zooplankton to fish, mammals and birds. Primary production in the Barents is on average 93 g C m -2 y -1, but interannually highly variable (±19%), responding to climate variability and change (e.g. variations in Atlantic Water inflow, the position of the ice edge and low-pressure pathways). The traditional focus upon large phytoplankton cells in polar regions seems less adequate in the Barents, as the cell carbon in the pelagic is most often dominated by small cells that are entangled in an efficient microbial loop that appears to be well coupled to the grazing food web. Primary production in the ice-covered waters of the Barents is clearly dominated by planktonic algae and the supply of ice biota by local production or advection is small. The pelagic-benthic coupling is strong, in particular in the marginal ice zone. In total 80% of the harvestable production is channelled through the deep-water communities and benthos. 19% of the harvestable production is grazed by the dominating copepods Calanus finmarchicus and C. glacialis in Atlantic or Arctic Water, respectively. These two species, in addition to capelin ( Mallotus villosus) and herring ( Clupea harengus), are the keystone organisms in the Barents that create the basis for the rich assemblage of higher trophic level organisms, facilitating one of the worlds largest fisheries (capelin, cod, shrimps, seals and whales). Less than 1% of the harvestable production is channelled through the most dominating higher trophic levels such as cod, harp seals, minke whales and sea birds. Atlantic cod, seals, whales, birds and man compete for harvestable energy with similar shares. Climate variability and change, differences in recruitment, variable resource availability, harvesting restrictions and management schemes will influence the resource exploitation between these competitors, that basically depend upon the efficient energy transfer from primary production to highly successful, lipid-rich zooplankton and pelagic fishes.

The origins of intensive marine fishing in medieval Europe: the English evidence.

PubMed

Barrett, James H; Locker, Alison M; Roberts, Callum M

2004-12-07

The catastrophic impact of fishing pressure on species such as cod and herring is well documented. However, the antiquity of their intensive exploitation has not been established. Systematic catch statistics are only available for ca.100 years, but large-scale fishing industries existed in medieval Europe and the expansion of cod fishing from the fourteenth century (first in Iceland, then in Newfoundland) played an important role in the European colonization of the Northwest Atlantic. History has demonstrated the scale of these late medieval and post-medieval fisheries, but only archaeology can illuminate earlier practices. Zooarchaeological evidence shows that the clearest changes in marine fishing in England between AD 600 and 1600 occurred rapidly around AD 1000 and involved large increases in catches of herring and cod. Surprisingly, this revolution predated the documented post-medieval expansion of England's sea fisheries and coincided with the Medieval Warm Period--when natural herring and cod productivity was probably low in the North Sea. This counterintuitive discovery can be explained by the concurrent rise of urbanism and human impacts on freshwater ecosystems. The search for 'pristine' baselines regarding marine ecosystems will thus need to employ medieval palaeoecological proxies in addition to recent fisheries data and early modern historical records.

The origins of intensive marine fishing in medieval Europe: the English evidence.

PubMed Central

Barrett, James H.; Locker, Alison M.; Roberts, Callum M.

2004-01-01

The catastrophic impact of fishing pressure on species such as cod and herring is well documented. However, the antiquity of their intensive exploitation has not been established. Systematic catch statistics are only available for ca.100 years, but large-scale fishing industries existed in medieval Europe and the expansion of cod fishing from the fourteenth century (first in Iceland, then in Newfoundland) played an important role in the European colonization of the Northwest Atlantic. History has demonstrated the scale of these late medieval and post-medieval fisheries, but only archaeology can illuminate earlier practices. Zooarchaeological evidence shows that the clearest changes in marine fishing in England between AD 600 and 1600 occurred rapidly around AD 1000 and involved large increases in catches of herring and cod. Surprisingly, this revolution predated the documented post-medieval expansion of England's sea fisheries and coincided with the Medieval Warm Period--when natural herring and cod productivity was probably low in the North Sea. This counterintuitive discovery can be explained by the concurrent rise of urbanism and human impacts on freshwater ecosystems. The search for 'pristine' baselines regarding marine ecosystems will thus need to employ medieval palaeoecological proxies in addition to recent fisheries data and early modern historical records. PMID:15590590

Daytime variations of absorbing aerosols above clouds in the southeast Atlantic

NASA Astrophysics Data System (ADS)

Chang, Y. Y.; Christopher, S. A.

2016-12-01

The daytime variation of aerosol optical depth (AOD) above maritime stratocumulus clouds in the southeast Atlantic is investigated by merging geostationary data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) with NASA A-Train data sets. SEVIRI's 15-minute above cloud AOD and below aerosol cloud optical depth (COD) retrieval provides the opportunity to assess their direct radiative forcing using actual cloud and aerosol properties instead of using fixed values from polar-orbiting measurements. The impact of overlying aerosols above clouds on the cloud mask products are compared with active spaceborne lidar to examine the performance of the product. Uncertainty analyses of aerosol properties on the estimation of optical properties and radiative forcing are addressed.

Early life history stages of Gulf sturgeon in the Suwannee River, Florida

USGS Publications Warehouse

Sulak, K.J.; Clugston, James P.

1998-01-01

Egg sampling confirmed that Suwannee River Gulf sturgeon Acipenser oxyrinchus desotoi, a subspecies of Atlantic sturgeon A. o. oxyrinchus use the same spawning site at river kilometer (rkm) 215 from the month of the river each year. Forty-nine eggs were recorded in 1995, and 368 were recorded in 1996. Spawning began 4-7 d after the March new moon in both years and lasted 10-11 d; in 1996, a second 10-d spawning round began on the April new moon. Developmental synchrony among eggs recovered suggested several discrete spawning events in both years. Total eggs deposited for three 1996 sampling days was estimated as 405,600-711,000/d, approximating the fecundity range of a large female Gulf sturgeon. Eggs were found only in the southern half of the river, an area with surface currents of 0.5-1.5 m/s and numerous eddies producing reverse bottom currents of 0.1-0.5 m/s. Egg substrate consisted of bedrock limestone thinly overlain by fine sand and densely distributed elliptical gravel 2-10 cm in diameter. Eggs were found predominantly in depths of 2-4 m at water temperatures of 17-21??C, conductivities of 50-100 ??S, and dissolved oxygen levels exceeding 5.0 mg/L. The Cody Scarp, 15 rkm above the spawning ground, may mark the upstream limit of spawning areas in the river. Three 2-4-month-old riverine juveniles (82-115 mm total length, TL) collected are the smallest yet captured from any river. Data for 18 riverine age-0 juveniles (to 350 mm TL) suggest that this stage lasts 6-10 months, terminating with migration of fish to the river mouth in January-February. Less than 2% of 461 juveniles captured at the estuarine river mouth (1990-1993) were under 350 mm TL. Riverine age-0 fish were collected over long shallow stretches (typically <4 m deep) of relatively barren sand (rkm 12-238).

Archived DNA reveals fisheries and climate induced collapse of a major fishery.

PubMed

Bonanomi, Sara; Pellissier, Loïc; Therkildsen, Nina Overgaard; Hedeholm, Rasmus Berg; Retzel, Anja; Meldrup, Dorte; Olsen, Steffen Malskær; Nielsen, Anders; Pampoulie, Christophe; Hemmer-Hansen, Jakob; Wisz, Mary Susanne; Grønkjær, Peter; Nielsen, Einar Eg

2015-10-22

Fishing and climate change impact the demography of marine fishes, but it is generally ignored that many species are made up of genetically distinct locally adapted populations that may show idiosyncratic responses to environmental and anthropogenic pressures. Here, we track 80 years of Atlantic cod (Gadus morhua) population dynamics in West Greenland using DNA from archived otoliths in combination with fish population and niche based modeling. We document how the interacting effects of climate change and high fishing pressure lead to dramatic spatiotemporal changes in the proportions and abundance of different genetic populations, and eventually drove the cod fishery to a collapse in the early 1970s. Our results highlight the relevance of fisheries management at the level of genetic populations under future scenarios of climate change.

Archived DNA reveals fisheries and climate induced collapse of a major fishery

PubMed Central

Bonanomi, Sara; Pellissier, Loïc; Therkildsen, Nina Overgaard; Hedeholm, Rasmus Berg; Retzel, Anja; Meldrup, Dorte; Olsen, Steffen Malskær; Nielsen, Anders; Pampoulie, Christophe; Hemmer-Hansen, Jakob; Wisz, Mary Susanne; Grønkjær, Peter; Nielsen, Einar Eg

2015-01-01

Fishing and climate change impact the demography of marine fishes, but it is generally ignored that many species are made up of genetically distinct locally adapted populations that may show idiosyncratic responses to environmental and anthropogenic pressures. Here, we track 80 years of Atlantic cod (Gadus morhua) population dynamics in West Greenland using DNA from archived otoliths in combination with fish population and niche based modeling. We document how the interacting effects of climate change and high fishing pressure lead to dramatic spatiotemporal changes in the proportions and abundance of different genetic populations, and eventually drove the cod fishery to a collapse in the early 1970s. Our results highlight the relevance of fisheries management at the level of genetic populations under future scenarios of climate change. PMID:26489934

Archived DNA reveals fisheries and climate induced collapse of a major fishery

NASA Astrophysics Data System (ADS)

Bonanomi, Sara; Pellissier, Loïc; Therkildsen, Nina Overgaard; Hedeholm, Rasmus Berg; Retzel, Anja; Meldrup, Dorte; Olsen, Steffen Malskær; Nielsen, Anders; Pampoulie, Christophe; Hemmer-Hansen, Jakob; Wisz, Mary Susanne; Grønkjær, Peter; Nielsen, Einar Eg

2015-10-01

Fishing and climate change impact the demography of marine fishes, but it is generally ignored that many species are made up of genetically distinct locally adapted populations that may show idiosyncratic responses to environmental and anthropogenic pressures. Here, we track 80 years of Atlantic cod (Gadus morhua) population dynamics in West Greenland using DNA from archived otoliths in combination with fish population and niche based modeling. We document how the interacting effects of climate change and high fishing pressure lead to dramatic spatiotemporal changes in the proportions and abundance of different genetic populations, and eventually drove the cod fishery to a collapse in the early 1970s. Our results highlight the relevance of fisheries management at the level of genetic populations under future scenarios of climate change.

Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes.

PubMed

Eikeset, Anne Maria; Dunlop, Erin S; Heino, Mikko; Storvik, Geir; Stenseth, Nils C; Dieckmann, Ulf

2016-12-27

The relative roles of density dependence and life history evolution in contributing to rapid fisheries-induced trait changes remain debated. In the 1930s, northeast Arctic cod (Gadus morhua), currently the world's largest cod stock, experienced a shift from a traditional spawning-ground fishery to an industrial trawl fishery with elevated exploitation in the stock's feeding grounds. Since then, age and length at maturation have declined dramatically, a trend paralleled in other exploited stocks worldwide. These trends can be explained by demographic truncation of the population's age structure, phenotypic plasticity in maturation arising through density-dependent growth, fisheries-induced evolution favoring faster-growing or earlier-maturing fish, or a combination of these processes. Here, we use a multitrait eco-evolutionary model to assess the capacity of these processes to reproduce 74 y of historical data on age and length at maturation in northeast Arctic cod, while mimicking the stock's historical harvesting regime. Our results show that model predictions critically depend on the assumed density dependence of growth: when this is weak, life history evolution might be necessary to prevent stock collapse, whereas when a stronger density dependence estimated from recent data is used, the role of evolution in explaining fisheries-induced trait changes is diminished. Our integrative analysis of density-dependent growth, multitrait evolution, and stock-specific time series data underscores the importance of jointly considering evolutionary and ecological processes, enabling a more comprehensive perspective on empirically observed stock dynamics than previous studies could provide.

Molecular ontogenesis of digestive capability and associated endocrine control in Atlantic cod (Gadus morhua) larvae.

PubMed

Kortner, Trond M; Overrein, Ingrid; Oie, Gunvor; Kjørsvik, Elin; Bardal, Tora; Wold, Per-Arvid; Arukwe, Augustine

2011-10-01

We have profiled the expression of twelve genes, in order to provide an overview on the molecular ontogeny of digestive capability with the associated endocrine control during Atlantic cod (Gadus morhua) larval development. Enzyme activity levels for the key digestive enzyme, trypsin, was also measured. Specifically, transcripts for trypsin, amylase, lipolytic enzymes: bile salt activated lipase (BAL), phospholipase A2 (PLA2) and Acyl CoA dehydrogenase (ACADM), regulatory peptides: neuropeptide Y (NPY), orexin (OX) cholecystokinin (CCK) and cocaine and amphetamine-related transcript (CART), the somatotropic factors: growth hormone (GH), preprosomatostatin 1 (PPSS1) and thyroid hormone receptors (TRα and TRβ) were analyzed using quatitative (real-time) polymerase chain reaction (qPCR). Trypsin and BAL mRNA levels peaked at approximately day 17 and 25 post-hatch, respectively, and thereafter displayed a decreasing pattern until metamorphosis. GH mRNA levels decreased moderately from 3 to 33dph, and thereafter, an increase was observed until 46dph. TRα mRNA levels showed a fluctuating pattern peaking at day 39 post-hatch. TRβ mRNA levels were too low to obtain quantitative measurements. Amylase mRNA slightly increased from day 3 to 17 post-hatch, and thereafter showed a steady decrease until day 60. Interestingly, PLA2 mRNA expression showed a consistent increase throughout the study period, indicating an increasingly important role during larval development. Overall, data from this study indicate that cod larvae show differential developmental mode of expression patterns for key genes and endocrine factors that regulate digestive capability, growth and development. These data are discussed in relation to larval trypsin enzyme activity and previous reports for other teleost species. Copyright © 2011 Elsevier Inc. All rights reserved.

Earth Observation

NASA Image and Video Library

2011-06-27

ISS028-E-009979 (27 June 2011) --- The Massachusetts coastline is featured in this image photographed by an Expedition 28 crew member on the International Space Station. The Crew Earth Observations team at NASA Johnson Space Center sends specific ground targets for photography up to the station crew on a daily basis, but sometimes the crew takes imagery on their own of striking displays visible from orbit. One such display, often visible to the ISS crew due to their ability to look outwards at angles between 0 and 90 degrees, is sunglint on the waters of Earth. Sunglint is caused by sunlight reflecting off of a water surface?much as light reflects from a mirror?directly towards the observer. Roughness variations of the water surface scatter the light, blurring the reflection and producing the typical silvery sheen of the sunglint area. The point of maximum sunglint is centered within Cape Cod Bay, the body of water partially enclosed by the ?hook? of Cape Cod in Massachusetts (bottom). Cape Cod was formally designated a National Seashore in 1966. Sunglint off the water provides sharp contrast with the coastline and the nearby islands of Martha?s Vineyard and Nantucket (lower left), both popular destinations for tourists and summer residents. To the north, rocky Cape Ann extends out into the Atlantic Ocean; the border with New Hampshire is located approximately 30 kilometers up the coast. Further to the west, the eastern half of Long Island, New York is visible emerging from extensive cloud cover over the mid-Atlantic and Midwestern States. Persistent storm tracks had been contributing to record flooding along rivers in the Midwest at the time this image was taken in late June 2011. Thin blue layers of the atmosphere, contrasted against the darkness of space, are visible extending along the Earth?s curvature at top.

Ocean warming and acidification modulate energy budget and gill ion regulatory mechanisms in Atlantic cod (Gadus morhua).

PubMed

Kreiss, C M; Michael, K; Lucassen, M; Jutfelt, F; Motyka, R; Dupont, S; Pörtner, H-O

2015-10-01

Ocean warming and acidification are threatening marine ecosystems. In marine animals, acidification is thought to enhance ion regulatory costs and thereby baseline energy demand, while elevated temperature also increases baseline metabolic rate. Here we investigated standard metabolic rates (SMR) and plasma parameters of Atlantic cod (Gadus morhua) after 3-4 weeks of exposure to ambient and future PCO2 levels (550, 1200 and 2200 µatm) and at two temperatures (10, 18 °C). In vivo branchial ion regulatory costs were studied in isolated, perfused gill preparations. Animals reared at 18 °C responded to increasing CO2 by elevating SMR, in contrast to specimens at 10 °C. Isolated gills at 10 °C and elevated PCO2 (≥1200 µatm) displayed increased soft tissue mass, in parallel to increased gill oxygen demand, indicating an increased fraction of gill in whole animal energy budget. Altered gill size was not found at 18 °C, where a shift in the use of ion regulation mechanisms occurred towards enhanced Na(+)/H(+)-exchange and HCO3 (-) transport at high PCO2 (2200 µatm), paralleled by higher Na(+)/K(+)-ATPase activities. This shift did not affect total gill energy consumption leaving whole animal energy budget unaffected. Higher Na(+)/K(+)-ATPase activities in the warmth might have compensated for enhanced branchial permeability and led to reduced plasma Na(+) and/or Cl(-) concentrations and slightly lowered osmolalities seen at 18 °C and 550 or 2200 µatm PCO2 in vivo. Overall, the gill as a key ion regulation organ seems to be highly effective in supporting the resilience of cod to effects of ocean warming and acidification.

Unravelling the Gordian knot! Key processes impacting overwintering larval survival and growth: A North Sea herring case study

NASA Astrophysics Data System (ADS)

Hufnagl, Marc; Peck, Myron A.; Nash, Richard D. M.; Dickey-Collas, Mark

2015-11-01

Unraveling the key processes affecting marine fish recruitment will ultimately require a combination of field, laboratory and modelling studies. We combined analyzes of long-term (30-year) field data on larval fish abundance, distribution and length, and biophysical model simulations of different levels of complexity to identify processes impacting the survival and growth of autumn- and winter-spawned Atlantic herring (Clupea harengus) larvae. Field survey data revealed interannual changes in intensity of utilization of the five major spawning grounds (Orkney/Shetland, Buchan, Banks north, Banks south, and Downs) as well as spatio-temporal variability in the length and abundance of overwintered larvae. The mean length of larvae captured in post-winter surveys was negatively correlated to the proportion of larvae from the southern-most (Downs) winter-spawning component. Furthermore, the mean length of larvae originating from all spawning components has decreased since 1990 suggesting ecosystem-wide changes impacting larval growth potential, most likely due to changes in prey fields. A simple biophysical model assuming temperature-dependent growth and constant mortality underestimated larval growth rates suggesting that larval mortality rates steeply declined with increasing size and/or age during winter as no match with field data could be obtained. In contrast better agreement was found between observed and modelled post-winter abundance for larvae originating from four spawning components when a more complex, physiological-based foraging and growth model was employed using a suite of potential prey field and size-based mortality scenarios. Nonetheless, agreement between field and model-derived estimates was poor for larvae originating from the winter-spawned Downs component. In North Sea herring, the dominant processes impacting larval growth and survival appear to have shifted in time and space highlighting how environmental forcing, ecosystem state and other factors can form a Gordian knot of marine fish recruitment processes. We highlight gaps in process knowledge and recommend specific field, laboratory and modelling studies which, in our opinion, are most likely to unravel the dominant processes and advance predictive capacity of the environmental regulation of recruitment in autumn and winter-spawned fishes in temperate areas such as herring in the North Sea.

The conserved Phe GH5 of importance for hemoglobin intersubunit contact is mutated in gadoid fish

PubMed Central

2014-01-01

Background Functionality of the tetrameric hemoglobin molecule seems to be determined by a few amino acids located in key positions. Oxygen binding encompasses structural changes at the interfaces between the α1β2 and α2β1 dimers, but also subunit interactions are important for the oxygen binding affinity and stability. The latter packing contacts include the conserved Arg B12 interacting with Phe GH5, which is replaced by Leu and Tyr in the αA and αD chains, respectively, of birds and reptiles. Results Searching all known hemoglobins from a variety of gnathostome species (jawed vertebrates) revealed the almost invariant Arg B12 coded by the AGG triplet positioned at an exon-intron boundary. Rare substitutions of Arg B12 in the gnathostome β globins were found in pig, tree shrew and scaled reptiles. Phe GH5 is also highly conserved in the β globins, except for the Leu replacement in the β1 globin of five marine gadoid species, gilthead seabream and the Comoran coelacanth, while Cys and Ile were found in burbot and yellow croaker, respectively. Atlantic cod β1 globin showed a Leu/Met polymorphism at position GH5 dominated by the Met variant in northwest-Atlantic populations that was rarely found in northeast-Atlantic cod. Site-specific analyses identified six consensus codons under positive selection, including 122β(GH5), indicating that the amino acid changes identified at this position may offer an adaptive advantage. In fact, computational mutation analysis showed that the replacement of Phe GH5 with Leu or Cys decreased the number of van der Waals contacts essentially in the deoxy form that probably causes a slight increase in the oxygen binding affinity. Conclusions The almost invariant Arg B12 and the AGG codon seem to be important for the packing contacts and pre-mRNA processing, respectively, but the rare mutations identified might be beneficial. The Leu122β1(GH5)Met and Met55β1(D6)Val polymorphisms in Atlantic cod hemoglobin modify the intradimer contacts B12-GH5 and H2-D6, while amino acid replacements at these positions in avian hemoglobin seem to be evolutionary adaptive in air-breathing vertebrates. The results support the theory that adaptive changes in hemoglobin functions are caused by a few substitutions at key positions. PMID:24655798

Evaluating the impact of above-cloud aerosols on cloud optical depth retrievals from MODIS

NASA Astrophysics Data System (ADS)

Alfaro, Ricardo

Using two different operational Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical depth (COD) retrievals (visible and shortwave infrared), the impacts of above-cloud absorbing aerosols on the standard COD retrievals are evaluated. For fine-mode aerosol particles, aerosol optical depth (AOD) values diminish sharply from the visible to the shortwave infrared channels. Thus, a suppressed above-cloud particle radiance aliasing effect occurs for COD retrievals using shortwave infrared channels. Aerosol Index (AI) from the spatially and temporally collocated Ozone Monitoring Instrument (OMI) are used to identify above-cloud aerosol particle loading over the southern Atlantic Ocean, including both smoke and dust from the African sub-continent. MODIS and OMI Collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data are used to constrain cloud phase and provide contextual above-cloud AOD values. The frequency of occurrence of above-cloud aerosols is depicted on a global scale for the spring and summer seasons from OMI and CALIOP, thus indicating the significance of the problem. Seasonal frequencies for smoke-over-cloud off the southwestern Africa coastline reach 20--50% in boreal summer. We find a corresponding low COD bias of 10--20% for standard MODIS COD retrievals when averaged OMI AI are larger than 1.0. No such bias is found over the Saharan dust outflow region off northern Africa, since both MODIS visible and shortwave in channels are vulnerable to dust particle aliasing, and thus a COD impact cannot be isolated with this method. A similar result is found for a smaller domain, in the Gulf of Tonkin region, from smoke advection over marine stratocumulus clouds and outflow into the northern South China Sea in spring. This study shows the necessity of accounting for the above-cloud aerosol events for future studies using standard MODIS cloud products in biomass burning outflow regions, through the use of collocated OMI AI and supplementary MODIS shortwave infrared COD products.

Historical Arctic Logbooks Provide Insights into Past Diets and Climatic Responses of Cod

PubMed Central

Townhill, Bryony L.; Maxwell, David; Engelhard, Georg H.; Simpson, Stephen D.; Pinnegar, John K.

2015-01-01

Gadus morhua (Atlantic cod) stocks in the Barents Sea are currently at levels not seen since the 1950s. Causes for the population increase last century, and understanding of whether such large numbers will be maintained in the future, are unclear. To explore this, we digitised and interrogated historical cod catch and diet datasets from the Barents Sea. Seventeen years of catch data and 12 years of prey data spanning 1930–1959 cover unexplored spatial and temporal ranges, and importantly capture the end of a previous warm period, when temperatures were similar to those currently being experienced. This study aimed to evaluate cod catch per unit effort and prey frequency in relation to spatial, temporal and environmental variables. There was substantial spatio-temporal heterogeneity in catches through the time series. The highest catches were generally in the 1930s and 1940s, although at some localities more cod were recorded late in the 1950s. Generalized Additive Models showed that environmental, spatial and temporal variables are all valuable descriptors of cod catches, with the highest occurring from 15–45°E longitude and 73–77°N latitude, at bottom temperatures between 2 and 4°C and at depths between 150 and 250 m. Cod diets were highly variable during the study period, with frequent changes in the relative frequencies of different prey species, particularly Mallotus villosus (capelin). Environmental variables were particularly good at describing the importance of capelin and Clupea harengus (herring) in the diet. These new analyses support existing knowledge about how the ecology of the region is controlled by climatic variability. When viewed in combination with more recent data, these historical relationships will be valuable in forecasting the future of Barents Sea fisheries, and in understanding how environments and ecosystems may respond. PMID:26331271

A Resolution to the Blue Whiting (Micromesistius poutassou) Population Paradox?

PubMed Central

Pointin, Fabien; Payne, Mark R.

2014-01-01

We provide the strongest evidence to date supporting the existence of two independent blue whiting (Micromesistius poutassou (Risso, 1827)) populations in the North Atlantic. In spite of extensive data collected in conjunction with the fishery, the population structure of blue whiting is poorly understood. On one hand, genetic, morphometric, otolith and drift modelling studies point towards the existence of two populations, but, on the other hand, observations of adult distributions point towards a single population. A paradox therefore arises in attempting to reconcile these two sets of information. Here we analyse 1100 observations of blue whiting larvae from the Continuous Plankton Recorder (CPR) from 1948–2005 using modern statistical techniques. We show a clear spatial separation between a northern spawning area, in the Rockall Trough, and a southern one, off the Porcupine Seabight. We further show a difference in the timing of spawning between these sites of at least a month, and meaningful differences in interannual variability. The results therefore support the two-population hypothesis. Furthermore, we resolve the paradox by showing that the acoustic observations cited in support of the single-population model are not capable of resolving both populations, as they occur too late in the year and do not extend sufficiently far south to cover the southern population: the confusion is the result of a simple observational artefact. We conclude that blue whiting in the North Atlantic comprises two populations. PMID:25184302

Horizontal movements of Atlantic blue marlin (Makaira nigricans) in the Gulf of Mexico

USGS Publications Warehouse

Kraus, R.T.; Wells, R.J.D.; Rooker, J.R.

2011-01-01

We examined movements of Atlantic blue marlin (Makaira nigricans) from the Gulf of Mexico based upon 42 pop-up archival transmitting (PAT) tags. Long deployments (including one 334-day track) revealed diverse movement patterns within the Gulf of Mexico. North-south seasonal changes in blue marlin distribution showed strong correspondence with established seasonal patterns of sea surface temperature and primary production. During the summer spawning season, blue marlin utilized outer shelf and shelf edge waters in the northern Gulf of Mexico, and longer duration tracks indicated overwintering habitats in the Bay of Campeche. Egress occurred throughout the year and was difficult to determine because some tracks ended in the Straits of Florida (n = 3) while other tracks recorded movement through it or the Yucatan Channel (n = 4). Our results indicate that Atlantic blue marlin have a more restricted geographic range of habitats than previously recognized and that the Gulf of Mexico provides spatially dynamic suitable habitat that is utilized year-round through seasonal movements. ?? 2011 Springer-Verlag.

Space Radar Image of Cape Cod, Massachusetts

NASA Technical Reports Server (NTRS)

1994-01-01

This spaceborne radar image shows the famous 'hook' of Cape Cod, Massachusetts. The Cape, which juts out into the Atlantic Ocean about 100 kilometers (62 miles) southeast of Boston, actually consists of sandy debris left behind by the great continental ice sheets when they last retreated from southern New England about 20,000 years ago. Today's landscape consists of sandy forests, fields of scrub oak and other bushes and grasses, salt marshes, freshwater ponds, as well as the famous beaches and sand dunes. In this image, thickly forested areas appear green, marshes are dark blue, ponds and sandy areas are black, and developed areas are mostly pink. The dark L-shape in the lower center is the airport runways in Hyannis, the Cape's largest town. The dark X-shape left of the center is Otis Air Force Base. The Cape Cod Canal, above and left of center, connects Buzzards Bay on the left with Cape Cod Bay on the right. The northern tip of the island of Martha's Vineyard is seen in the lower left. The tip of the Cape, in the upper right, includes the community of Provincetown, which appears pink, and the protected National Seashore areas of sand dunes that parallel the Atlantic coast east of Provincetown. Scientists are using radar images like this one to study delicate coastal environments and the effects of human activities on the ecosystem and landscape. This image was acquired by Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 15, 1994. The image is 81.7 kilometers by 43.1 kilometers (50.7 miles by 26.7 miles) and is centered at 41.8 degrees north latitude, 70.3 degrees west longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted and received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

Black-legged kittiwakes as messengers of Atlantification in the Arctic.

PubMed

Vihtakari, Mikko; Welcker, Jorg; Moe, Børge; Chastel, Olivier; Tartu, Sabrina; Hop, Haakon; Bech, Claus; Descamps, Sébastien; Gabrielsen, Geir Wing

2018-01-19

Climate warming is rapidly altering marine ecosystems towards a more temperate state on the European side of the Arctic. However, this "Atlantification" has rarely been confirmed, as long-term datasets on Arctic marine organisms are scarce. We present a 19-year time series (1982-2016) of diet samples from black-legged kittiwakes as an indicator of the changes in a high Arctic marine ecosystem (Kongsfjorden, Svalbard). Our results highlight a shift from Arctic prey dominance until 2006 to a more mixed diet with high contribution of Atlantic fishes. Capelin, an Atlantic species, dominated the diet composition in 2007, marking a shift in the food web. The occurrence of polar cod, a key Arctic fish species, positively correlated with sea ice index, whereas Atlantic species demonstrated the opposite correlation indicating that the diet shift was likely connected with recent climate warming. Kittiwakes, which gather available fish and zooplankton near the sea surface to feed their chicks, can act as messengers of ecosystem change. Changes in their diet reveal that the Kongsfjord system has drifted in an Atlantic direction over the last decade.

Features in the Lipid Status of Two Generations of Fingerlings (0+) of Atlantic Salmon (Salmo salar L.) Inhabiting the Arenga River (Kola Peninsula).

PubMed

Nemova, Nina N; Murzina, Svetlana A; Nefedova, Zinaida A; Veselov, Alexey E

2015-07-30

The present research focused on determining the lipid status of salmon fingerlings (0+) in early development after dispersal form groups of spawning nests in biotopes of different hydrological conditions. The revealed qualitative and quantitative differences in the levels of phospholipids and fatty acids among two generations of Atlantic salmon fingerlings (0+) living in different biotopes of the Arenga River (a tributary of the Varzuga River) may be associated with the peculiarities of their genetically determined processes of the biosynthesis and modification of individual lipid classes and trophoecological factors (food spectrum, quality and availability of food objects, and hydrological regime). The research was organized to observe the dynamics of these developmental changes from ages 0+ to 2+.

Broad-scale climate influences on spring-spawning herring (Clupea harengus, L.) recruitment in the Western Baltic Sea.

PubMed

Gröger, Joachim P; Hinrichsen, Hans-Harald; Polte, Patrick

2014-01-01

Climate forcing in complex ecosystems can have profound implications for ecosystem sustainability and may thus challenge a precautionary ecosystem management. Climatic influences documented to affect various ecological functions on a global scale, may themselves be observed on quantitative or qualitative scales including regime shifts in complex marine ecosystems. This study investigates the potential climatic impact on the reproduction success of spring-spawning herring (Clupea harengus) in the Western Baltic Sea (WBSS herring). To test for climate effects on reproduction success, the regionally determined and scientifically well-documented spawning grounds of WBSS herring represent an ideal model system. Climate effects on herring reproduction were investigated using two global indices of atmospheric variability and sea surface temperature, represented by the North Atlantic Oscillation (NAO) and the Atlantic Multi-decadal Oscillation (AMO), respectively, and the Baltic Sea Index (BSI) which is a regional-scale atmospheric index for the Baltic Sea. Moreover, we combined a traditional approach with modern time series analysis based on a recruitment model connecting parental population components with reproduction success. Generalized transfer functions (ARIMAX models) allowed evaluating the dynamic nature of exogenous climate processes interacting with the endogenous recruitment process. Using different model selection criteria our results reveal that in contrast to NAO and AMO, the BSI shows a significant positive but delayed signal on the annual dynamics of herring recruitment. The westward influence of the Siberian high is considered strongly suppressing the influence of the NAO in this area leading to a higher explanatory power of the BSI reflecting the atmospheric pressure regime on a North-South transect between Oslo, Norway and Szczecin, Poland. We suggest incorporating climate-induced effects into stock and risk assessments and management strategies as part of the EU ecosystem approach to support sustainable herring fisheries in the Western Baltic Sea.

Broad-Scale Climate Influences on Spring-Spawning Herring (Clupea harengus, L.) Recruitment in the Western Baltic Sea

PubMed Central

Gröger, Joachim P.; Hinrichsen, Hans-Harald; Polte, Patrick

2014-01-01

Climate forcing in complex ecosystems can have profound implications for ecosystem sustainability and may thus challenge a precautionary ecosystem management. Climatic influences documented to affect various ecological functions on a global scale, may themselves be observed on quantitative or qualitative scales including regime shifts in complex marine ecosystems. This study investigates the potential climatic impact on the reproduction success of spring-spawning herring (Clupea harengus) in the Western Baltic Sea (WBSS herring). To test for climate effects on reproduction success, the regionally determined and scientifically well-documented spawning grounds of WBSS herring represent an ideal model system. Climate effects on herring reproduction were investigated using two global indices of atmospheric variability and sea surface temperature, represented by the North Atlantic Oscillation (NAO) and the Atlantic Multi-decadal Oscillation (AMO), respectively, and the Baltic Sea Index (BSI) which is a regional-scale atmospheric index for the Baltic Sea. Moreover, we combined a traditional approach with modern time series analysis based on a recruitment model connecting parental population components with reproduction success. Generalized transfer functions (ARIMAX models) allowed evaluating the dynamic nature of exogenous climate processes interacting with the endogenous recruitment process. Using different model selection criteria our results reveal that in contrast to NAO and AMO, the BSI shows a significant positive but delayed signal on the annual dynamics of herring recruitment. The westward influence of the Siberian high is considered strongly suppressing the influence of the NAO in this area leading to a higher explanatory power of the BSI reflecting the atmospheric pressure regime on a North-South transect between Oslo, Norway and Szczecin, Poland. We suggest incorporating climate-induced effects into stock and risk assessments and management strategies as part of the EU ecosystem approach to support sustainable herring fisheries in the Western Baltic Sea. PMID:24586279

Are life histories of Norwegian fjord herring populations of Pacific ancestry similar to those of Atlantic or Pacific herring?

NASA Astrophysics Data System (ADS)

Mikkelsen, Nina; Pedersen, Torstein; dos Santos Schmidt, Thassya Christina; Falk-Petersen, Inger-Britt; Slotte, Aril

2018-04-01

Herring from two unexploited fjord populations, Lake Rossfjord (LRH, n = 100) and Balsfjord (BFH, n = 420) in northern Norway, were sampled in 2014 and 2015. Life history characteristics were analysed and compared to the oceanic Norwegian spring-spawning herring (NSSH), and other Atlantic and Pacific herring stocks. Genetic studies have shown that LRH and BFH are ancestors evolved from Pacific herring that hybridized with Atlantic herring. This study shows that both LRH and BFH mature at a relatively early age, at 2-3 years and ca. 4 years respectively, compared to ca. 5 years for NSSH. The spawning stocks of LRH and BFH consist of small fish and contain relatively few age classes. Both fjord populations have slow growth after sexual maturity; LRH has a very low asymptotic length (L∞ = 19.8 cm), while that of BFH is higher (L∞ of 28.5 cm); both these values being lower than that of NSSH (L∞ of ca. 37 cm). The somatic relative fecundity of LRH is 176.6 oocytes g- 1, while the somatic relative fecundity of recruit and repeat BFH spawners is 152.4 and 183.1 oocytes g- 1, respectively. These estimates are lower than those for NSSH and other Atlantic herring fjord populations, but comparable with other Pacific herring. Due to the smaller body sizes of the spawners in the LRH and BFH populations, absolute fecundity is much lower than in NSSH. The gonadosomatic indices of prespawning fish are similar in LRH and BFH, being slightly higher compared to the NSSH, but lower than values reported for Pacific herring. The natural mortality rates of LRH and BFH (M = 0.64 year- 1 and M = 0.76 year- 1, respectively) are much higher than in NSSH (M = 0.15 year- 1) and most other Atlantic herring populations, except the Lusterfjord herring. However, these high mortality rates are similar to those of several Pacific herring populations. It is concluded that LRH and BFH show low somatic growth and high natural mortality rate. These life history characteristics differ from those of NSSH, but are similar to some Pacific herring populations adapted to a coastal high-mortality risk environment.

Life history and status of Shortnose Sturgeon (Acipenser brevirostrum LeSueur, 1818)

USGS Publications Warehouse

Kynard, Boyd; Bolden, Stephania; Kieffer, Micah; Collins, Mark; Brundage, Hal; Hilton, Eric; Litvak, Mark; Kinnison, Michael T.; King, Timothy L.; Peterson, Douglas C.

2016-01-01

Shortnose Sturgeon = SNS (Acipenser brevirostrum) is a small diadromous species with most populations living in large Atlantic coast rivers and estuaries of North America from New Brunswick, Canada, to GA, USA. There are no naturally landlocked populations, so all populations require access to fresh water and salt water to complete a natural life cycle. The species is amphidromous with use of fresh water and salt water (the estuary) varied across the species range, a pattern that may reflect whether freshwater or saltwater habitats provide optimal foraging and growth conditions. Migration is a dominant behavior during life history, beginning when fish are hatchling free embryos (southern SNS) or larvae (northeastern and far northern SNS). Migration continues by juveniles and nonspawning adult life stages on an individual time schedule with fish moving between natal river and estuary to forage or seek refuge, and by spawning adults migrating to and from riverine spawning grounds. Coastal movements by adults throughout the range (but particularly in the Gulf of Maine = GOM and among southern rivers) suggest widespread foraging, refuge use, and widespread colonization of new rivers. Colonization may also be occurring in the Potomac River, MD–VA–DC (midAtlantic region). Genetic studies (mtDNA and nDNA) identified distinct individual river populations of SNS, and recent rangewide nDNA studies identified five distinct evolutionary lineages of SNS in the USA: a northern metapopulation in GOM rivers; the Connecticut River; the Hudson River; a Delaware River–Chesapeake Bay metapopulation; and a large southern metapopulation (SC rivers to Altamaha River, GA). The Saint John River, NB, Canada, in the Bay of Fundy (north of the GOM), is the sixth distinct genetic lineage within SNS. Life history information from telemetry tracking supports the genetic information documenting extensive movement of adults among rivers within the three metapopulations. However, individual river populations with spawning adults are still the best basal unit for management and recovery planning. The focus on individual river populations should be complemented with attention to migratory processes and corridors that foster metapopulation level risks and benefits. The species may be extirpated at the center of the range, i.e., the midAtlantic region (Chesapeake Bay, MD–VA, and probably, NC), but large rivers in VA, including the James and Potomac rivers, need study. The largest SNS populations in GOM and northeastern rivers, like the Kennebec, Hudson, and Delaware rivers, typically have tens of thousands of adults. This contrasts with southern rivers, where rivers typically have much fewer (6000 adults). River damming in the 19th and 20th Centuries extirpated some populations, and also, created two dysfunctional segmented populations: the Connecticut River SNS in CT–MA and the SanteeCooper rivers–Lake Marion SNS in SC. The major anthropogenic impact on SNS in marine waters is fisheries bycatch. The major impacts that determine annual recruitment success occur in freshwater firstly, where adult spawning migrations and spawning are blocked or spawning success is affected by river regulation and secondly, where poor survival of early life stages is caused by river dredging, pollution, and unregulated impingement/entrainment in water withdrawal facilities. Climate warming has the potential to reduce abundance or eliminate SNS in many rivers, particularly in the South. In 1998, the National Marine Fisheries Service (NMFS) recommended management of 19 rivers as distinct population segments (DPSs) based on strong fidelity to natal rivers. A Biological Assessment completed in 2010 reaffirmed this approach. NMFS has not formally listed DPSs under the ESA and the species remains listed as endangered rangewide in the USA.

Changes in the Distribution of Atlantic Bluefin Tuna (Thunnus thynnus) in the Gulf of Maine 1979-2005

PubMed Central

Golet, Walter J.; Galuardi, Benjamin; Cooper, Andrew B.; Lutcavage, Molly E.

2013-01-01

The Gulf of Maine, NW Atlantic Ocean, is a productive, seasonal foraging ground for Atlantic bluefin tuna (Thunnus thynnus), but commercial landings of adult size classes were up to 40% below the allocated total allowable catch between 2004 to 2008 for the rod and reel, harpoon, and purse seine categories in the Gulf of Maine. Reduction in Atlantic bluefin tuna catches in the Gulf of Maine could represent a decline in spawning stock biomass, but given wide-ranging, complex migration patterns, and high energetic requirements, an alternative hypothesis is that their dispersal patterns shifted to regions with higher prey abundance or profitability, reducing availability to U.S. fishing fleets. This study fit generalized linear models to Atlantic bluefin tuna landings data collected from fishermen’s logbooks (1979-2005) as well as the distances between bluefin tuna schools and Atlantic herring ( Clupea harengus ), a primary prey species, to test alternative hypotheses for observed shifts in Atlantic bluefin tuna availability in the Gulf of Maine. For the bluefin model, landings varied by day of year, latitude and longitude. The effect of latitude differed by day of year and the effect of longitude differed by year. The distances between Atlantic bluefin tuna schools and Atlantic herring schools were significantly smaller (p<0.05) than would be expected from a randomly distributed population. A time series of average bluefin tuna school positions was positively correlated with the average number of herring captured per tow on Georges Bank in spring and autumn surveys respectively (p<0.01, r2=0.24, p<0.01, r2=0.42). Fishermen’s logbooks contributed novel spatial and temporal information towards testing these hypotheses for the bluefin tuna fishery. PMID:24069420

Changes in the distribution of atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Maine 1979-2005.

PubMed

Golet, Walter J; Galuardi, Benjamin; Cooper, Andrew B; Lutcavage, Molly E

2013-01-01

The Gulf of Maine, NW Atlantic Ocean, is a productive, seasonal foraging ground for Atlantic bluefin tuna (Thunnus thynnus), but commercial landings of adult size classes were up to 40% below the allocated total allowable catch between 2004 to 2008 for the rod and reel, harpoon, and purse seine categories in the Gulf of Maine. Reduction in Atlantic bluefin tuna catches in the Gulf of Maine could represent a decline in spawning stock biomass, but given wide-ranging, complex migration patterns, and high energetic requirements, an alternative hypothesis is that their dispersal patterns shifted to regions with higher prey abundance or profitability, reducing availability to U.S. fishing fleets. This study fit generalized linear models to Atlantic bluefin tuna landings data collected from fishermen's logbooks (1979-2005) as well as the distances between bluefin tuna schools and Atlantic herring (Clupeaharengus), a primary prey species, to test alternative hypotheses for observed shifts in Atlantic bluefin tuna availability in the Gulf of Maine. For the bluefin model, landings varied by day of year, latitude and longitude. The effect of latitude differed by day of year and the effect of longitude differed by year. The distances between Atlantic bluefin tuna schools and Atlantic herring schools were significantly smaller (p<0.05) than would be expected from a randomly distributed population. A time series of average bluefin tuna school positions was positively correlated with the average number of herring captured per tow on Georges Bank in spring and autumn surveys respectively (p<0.01, r(2)=0.24, p<0.01, r(2)=0.42). Fishermen's logbooks contributed novel spatial and temporal information towards testing these hypotheses for the bluefin tuna fishery.

Differential response of continental stock complexes of Atlantic salmon (Salmo salar) to the Atlantic Multidecadal Oscillation

NASA Astrophysics Data System (ADS)

Friedland, Kevin D.; Shank, Burton V.; Todd, Christopher D.; McGinnity, Philip; Nye, Janet A.

2014-05-01

Atlantic salmon, Salmo salar, in the North Atlantic are managed as a set of population complexes distributed in North America and Europe. In recent years, these complexes have experienced reduced marine survival and many populations within the complexes are at risk, especially those at the southern ends of the species amphi-Atlantic range. Atlantic salmon is an anadromous fish dividing its life history between residence in freshwater and the marine environment. The freshwater portion of the life history includes spawning and the rearing of juveniles where in-river production has tended to be relatively stable, whereas the first year at sea, termed the post-smolt year, is characterized by more variable rates of mortality. Although their habitats are widely separated geographically along the North Atlantic seaboards, strong recruitment coherence exists between North American and European stock complexes. This recruitment coherence is correlated with ocean temperature variation associated with the Atlantic Multidecadal Oscillation (AMO). The North Atlantic Oscillation (NAO) appears to be relatively unimportant as a driver of salmon abundance. The mechanism determining the link between AMO-related thermal variation and abundance appears to differ fundamentally for the two continental stock groupings. Whereas ocean climate variability during the first springtime months of juvenile salmon migration to sea appears to be important to the survival of North American stocks, summer climate variation appears to be central to adult recruitment variation for European stocks. This contrast in seasonal effects appears to be related to the varying roles of predation pressure and size-related mortality on the continental stock complexes. The anticipated warming due to global climate change will impose thermal conditions on salmon populations outside historical context and challenge the ability of many populations to persist.

The acute phase response of cod (Gadus morhua L.): expression of immune response genes.

PubMed

Audunsdottir, Sigridur S; Magnadottir, Bergljot; Gisladottir, Berglind; Jonsson, Zophonias O; Bragason, Birkir Th

2012-02-01

An acute phase response (APR) was experimentally induced in Atlantic cod (Gadus morhua L.) by intramuscular injection of turpentine oil. The change in the expression of immune related genes was monitored in the anterior kidney and the spleen over a period of 7 days. The genes examined were two types of pentraxins, apolipoprotein A1 (ApoA-I), the complement component C3, interleukin-1β (IL-1β), transferrin, cathelicidin, and hepcidin. All genes were constitutively expressed in both organs and their expression amplified by the turpentine injection. A pattern of response was observed both with respect to the organ preference and to the timing of a maximum response. The increased gene expression of the pentraxins, ApoA-I and C3 was restricted to the anterior kidney, the gene expression of IL-1β, cathelicidin, and transferrin increased in both organs, while hepcidin gene expression was only significantly increased in the spleen. The pentraxins and ApoA-I appear to be early mediators of APR in cod, possibly stimulating C3 and IL-1β response, while the antimicrobial peptides may play a minor role. The increase in transferrin gene expression in both organs, and apparent indifference to cortisol release associated with the turpentine injection, suggests that this could be a typical acute phase protein in cod. Copyright © 2011 Elsevier Ltd. All rights reserved.

Creatine kinase and mitochondrial respiration in hearts of trout, cod and freshwater turtle.

PubMed

Birkedal, R; Gesser, H

2003-08-01

The importance of the creatine kinase system in the cardiac muscle of ectothermic vertebrates is unclear. Mammalian cardiac muscle seems to be structurally organized in a manner that compartmentalizes the intracellular environment as evidenced by the substantially higher mitochondrial apparent Km for ADP in skinned fibres compared to isolated mitochondria. A mitochondrial fraction of creatine kinase is functionally coupled to the mitochondrial respiration, and the transport of phosphocreatine and creatine as energy equivalents of ATP and ADP, respectively, increases the mitochondrial apparent ADP affinity, i.e. lowers the Km. This function of creatine kinase seems to be absent in hearts of frog species. To find out whether this applies to hearts of ectothermic vertebrate species in general, we investigated the effect of creatine on the mitochondrial respiration of saponin-skinned fibres from the ventricle of rainbow trout, Atlantic cod and freshwater turtle. For all three species, the apparent Km for ADP appeared to be substantially higher than for isolated mitochondria. Creatine lowered this Km in trout and turtle, thus indicating a functional coupling between mitochondrial creatine kinase and respiration. However, creatine had no effect on Km in cod ventricle. In conclusion, the creatine kinase-system in trout and turtle hearts seems to fulfil the same functions as in the mammalian heart, i.e. facilitating energy transport and communication between cellular compartments. In cod heart, however, this does not seem to be the case.

Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). Spot

DTIC Science & Technology

1989-02-01

lateral line scales, 72-77; Norfolk spot, golden croaker (during gill rakers short, 8 to 12 on the spawning season ), croaker, goody, upper limb and 20 to... pteropods , larval Sinc lage-cal motaltie of pelecypods, and cyclopoid copepods juveniles are not observed in the elecypodst and cyc)opo copepodsnursry...and R.S. Birdsong. 1985. Beaufort, N.C. Seasonal occurrence of larval and juvenile fishes in a Virginia Engle, D.W., and R.M. Thuotte. 1976

Lower New England, USA

NASA Technical Reports Server (NTRS)

1973-01-01

This view of lower New England, (41.5N, 72.0W) shows a rare cloud-free area stretching from northern Long Island across the states of Connecticut, Rhode Island and Massachusetts. The total area covered by this photo is more than 25,000 square miles and includes all of Rhode Island, most of Massachusetts and Connecticut, part of New York and the coastal waters of the Atlantic Ocean. Cape Cod, Boston and the offshore islands are distinctive features.

Climate induced temperature effects on growth performance, fecundity and recruitment in marine fish: developing a hypothesis for cause and effect relationships in Atlantic cod ( Gadus morhua) and common eelpout ( Zoarces viviparus)

NASA Astrophysics Data System (ADS)

Pörtner, H. O.; Berdal, B.; Blust, R.; Brix, O.; Colosimo, A.; De Wachter, B.; Giuliani, A.; Johansen, T.; Fischer, T.; Knust, R.; Lannig, G.; Naevdal, G.; Nedenes, A.; Nyhammer, G.; Sartoris, F. J.; Serendero, I.; Sirabella, P.; Thorkildsen, S.; Zakhartsev, M.

2001-12-01

Effects of global warming on animal distribution and performance become visible in many marine ecosystems. The present study was designed to develop a concept for a cause and effect understanding with respect to temperature changes and to explain ecological findings based on physiological processes. The concept is based on a wide comparison of invertebrate and fish species with a special focus on recent data obtained in two model species of fish. These fish species are both characterized by northern and southern distribution limits in the North Atlantic: eelpout ( Zoarces viviparus), as a typical non-migrating inhabitant of the coastal zone and the cod ( Gadus morhua), as a typical inhabitant of the continental shelf with a high importance for fisheries. Mathematical modelling demonstrates a clear significant correlation between climate induced temperature fluctuations and the recruitment of cod stocks. Growth performance in cod is optimal at temperatures close to 10°C, regardless of the population investigated in a latitudinal cline. However, temperature specific growth rates decrease at higher latitudes. Also, fecundity is less in White Sea than in North and Baltic Sea cod or eelpout populations. These findings suggest that a cold-induced shift in energy budget occurs which is unfavorable for growth performance and fecundity. Thermal tolerance limits shift depending on latitude and are characterized by oxygen limitation at both low or high temperatures. Oxygen supply to tissues is optimized at low temperature by a shift in hemoglobin isoforms and oxygen binding properties to lower affinities and higher unloading potential. Protective stimulation of heat shock protein synthesis was not observed. According to a recent model of thermal tolerance the downward shift of tolerance limits during cold adaptation is associated with rising mitochondrial densities and, thus, aerobic capacity and performance in the cold, especially in eurythermal species. At the same time the costs of mitochondrial maintenance reflected by mitochondrial proton leakage should rise leaving a lower energy fraction for growth and reproduction. The preliminary conclusion can be drawn that warming will cause a northern shift of distribution limits for both species with a rise in growth performance and fecundity larger than expected from the Q 10 effect in the north and lower growth or even extinction of the species in the south. Such a shift may heavily affect fishing activities in the North Sea.

Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes

PubMed Central

Eikeset, Anne Maria; Dunlop, Erin S.; Heino, Mikko; Storvik, Geir; Stenseth, Nils C.; Dieckmann, Ulf

2016-01-01

The relative roles of density dependence and life history evolution in contributing to rapid fisheries-induced trait changes remain debated. In the 1930s, northeast Arctic cod (Gadus morhua), currently the world’s largest cod stock, experienced a shift from a traditional spawning-ground fishery to an industrial trawl fishery with elevated exploitation in the stock’s feeding grounds. Since then, age and length at maturation have declined dramatically, a trend paralleled in other exploited stocks worldwide. These trends can be explained by demographic truncation of the population’s age structure, phenotypic plasticity in maturation arising through density-dependent growth, fisheries-induced evolution favoring faster-growing or earlier-maturing fish, or a combination of these processes. Here, we use a multitrait eco-evolutionary model to assess the capacity of these processes to reproduce 74 y of historical data on age and length at maturation in northeast Arctic cod, while mimicking the stock’s historical harvesting regime. Our results show that model predictions critically depend on the assumed density dependence of growth: when this is weak, life history evolution might be necessary to prevent stock collapse, whereas when a stronger density dependence estimated from recent data is used, the role of evolution in explaining fisheries-induced trait changes is diminished. Our integrative analysis of density-dependent growth, multitrait evolution, and stock-specific time series data underscores the importance of jointly considering evolutionary and ecological processes, enabling a more comprehensive perspective on empirically observed stock dynamics than previous studies could provide. PMID:27940913

Efficacy and toxicity of iodine disinfection of Atlantic salmon eggs

USGS Publications Warehouse

Chalupnicki, M.A.; Ketola, H.G.; Starliper, C.E.; Gallagher, D.

2011-01-01

Recent interest in the restoration of Atlantic salmon Salmo salar in the Great Lakes has given rise to new culture techniques and management programs designed to reduce pathogen transmission while stabilizing and enhancing wild populations. We examined the toxicity of iodine to Atlantic salmon eggs and its effectiveness as a disinfectant against bacteria on egg surfaces. We spawned and fertilized eight gravid Atlantic salmon from Cayuga Lake, New York, and exposed their eggs to 10 concentrations of iodine (5, 10, 50, 75, 100, 500, 750, 1,000, 5,000, and 7,500 mg/L) for 30 min during water hardening. An additional subsample of unfertilized eggs was also exposed to some of the same concentrations of iodine (5, 10, 50, 75, and 100 mg/L) to determine the efficiency of disinfection. Viable eggs were only obtained from four females. Survival of eggs to the eyed stage and hatch tended to be reduced at iodine concentrations of 50 and 75 mg/L and was significantly reduced at concentrations of 100 mg/L iodine or more. We calculated the concentrations of iodine that killed 50% of the Atlantic salmon eggs at eye-up and hatch to be 175 and 85 mg/L, respectively. Aeromonas veronii, A. schubertii, A. hydrophila, A. caviae, Plesiomonas shiggeloides, and Citrobacter spp. were the predominant bacteria present on the surface of green eggs and were significantly reduced by an iodine immersion. The use of iodine as a disinfectant on Atlantic salmon eggs was effective at low concentrations (50–75 mg/L), for which toxicity to Atlantic salmon was minimal.

Marine biodiversity, ecosystem functioning, and carbon cycles.

PubMed

Beaugrand, Grégory; Edwards, Martin; Legendre, Louis

2010-06-01

Although recent studies suggest that climate change may substantially accelerate the rate of species loss in the biosphere, only a few studies have focused on the potential consequences of a spatial reorganization of biodiversity with global warming. Here, we show a pronounced latitudinal increase in phytoplanktonic and zooplanktonic biodiversity in the extratropical North Atlantic Ocean in recent decades. We also show that this rise in biodiversity paralleled a decrease in the mean size of zooplanktonic copepods and that the reorganization of the planktonic ecosystem toward dominance by smaller organisms may influence the networks in which carbon flows, with negative effects on the downward biological carbon pump and demersal Atlantic cod (Gadus morhua). Our study suggests that, contrary to the usual interpretation of increasing biodiversity being a positive emergent property promoting the stability/resilience of ecosystems, the parallel decrease in sizes of planktonic organisms could be viewed in the North Atlantic as reducing some of the services provided by marine ecosystems to humans.

Recruitment success of different fish stocks in the North Sea in relation to climate variability

NASA Astrophysics Data System (ADS)

Dippner, Joachim W.

1997-09-01

Long-term data of year class strengths of different commercially harvested fish stocks based on a virtual population analysis (VPA) are available from ICES. The anomalies of these long-term data sets of year class strength are analyzed using Empirical Orthogonal Functions (EOFs) and are related to climate variability: the anomalies of the sea surface temperature (SST) in the northern North Sea and the North Atlantic Oscillation (NAO) index. A Canonical Correlation Analysis (CCA) between the leading eigenmodes is performed. The results suggest that the variability in the fish recruitment of western mackerel and three gadoids, namely North Sea cod, North Sea saithe, and North Sea whiting is highly correlated to the variability of the North Sea SST which is directly influenced by the NAO. For North Sea haddock and herring no meaningful correlation exists to North Sea SST and NAO. The results allow the conclusion that is seems possible to predict long-term changes in the fish recruitment from climate change scenarios for North Sea cod, North Sea saithe and western mackerel. Furthermore, the results indicate the possibility of recruitment failure for North Sea cod, North Sea whiting, and western mackerel in the case of global warming.

Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition.

PubMed

Rodriguez-Marin, Enrique; Ortiz, Mauricio; Ortiz de Urbina, José María; Quelle, Pablo; Walter, John; Abid, Noureddine; Addis, Piero; Alot, Enrique; Andrushchenko, Irene; Deguara, Simeon; Di Natale, Antonio; Gatt, Mark; Golet, Walter; Karakulak, Saadet; Kimoto, Ai; Macias, David; Saber, Samar; Santos, Miguel Neves; Zarrad, Rafik

2015-01-01

The compiled data for this study represents the first Atlantic and Mediterranean-wide effort to pool all available biometric data for Atlantic bluefin tuna (Thunnus thynnus) with the collaboration of many countries and scientific groups. Biometric relationships were based on an extensive sampling (over 140,000 fish sampled), covering most of the fishing areas for this species in the North Atlantic Ocean and Mediterranean Sea. Sensitivity analyses were carried out to evaluate the representativeness of sampling and explore the most adequate procedure to fit the weight-length relationship (WLR). The selected model for the WLRs by stock included standardized data series (common measurement types) weighted by the inverse variability. There was little difference between annual stock-specific round weight-straight fork length relationships, with an overall difference of 6% in weight. The predicted weight by month was estimated as an additional component in the exponent of the weight-length function. The analyses of monthly variations of fish condition by stock, maturity state and geographic area reflect annual cycles of spawning and feeding behavior. We update and improve upon the biometric relationships for bluefin currently used by the International Commission for the Conservation of Atlantic Tunas, by incorporating substantially larger datasets than ever previously compiled, providing complete documentation of sources and employing robust statistical fitting. WLRs and other conversion factors estimated in this study differ from the ones used in previous bluefin stock assessments.

Evaluating the impact of aerosol particles above cloud on cloud optical depth retrievals from MODIS

NASA Astrophysics Data System (ADS)

Alfaro-Contreras, Ricardo; Zhang, Jianglong; Campbell, James R.; Holz, Robert E.; Reid, Jeffrey S.

2014-05-01

Using two different operational Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical depth (COD) retrievals (0.86 versus 1.6 µm), we evaluate the impact of above-cloud smoke aerosol particles on near-IR (0.86 µm) COD retrievals. Aerosol Index (AI) from the collocated Ozone Monitoring Instrument (OMI) are used to identify above-cloud aerosol particle loading over the southern Atlantic Ocean, including both smoke and dust from the African subcontinent. Collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation data constrain cloud phase and provide contextual above-cloud aerosol optical depth. The frequency of occurrence of above-cloud aerosol events is depicted on a global scale for the spring and summer seasons from OMI and Cloud Aerosol Lidar with Orthogonal Polarization. Seasonal frequencies for smoke-over-cloud off the southwestern Africa coastline reach 20-50% in boreal summer. We find a corresponding low COD bias of 10-20% for standard MODIS COD retrievals when averaged OMI AI are larger than 1. No such bias is found over the Saharan dust outflow region off northern Africa, since both MODIS 0.86 and 1.6 µm channels are vulnerable to radiance attenuation due to dust particles. A similar result is found for a smaller domain, in the Gulf of Tonkin region, from smoke advection over marine stratocumulus clouds and outflow into the northern South China Sea in spring. This study shows the necessity of accounting for the above-cloud aerosol events for future studies using standard MODIS cloud products in biomass burning outflow regions, through the use of collocated OMI AI and supplementary MODIS 1.6 µm COD products.

Increased natural mortality at low abundance can generate an Allee effect in a marine fish.

PubMed

Kuparinen, Anna; Hutchings, Jeffrey A

2014-10-01

Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics into its opposite-a demographic Allee effect. Northwest Atlantic cod (Gadus morhua) stocks collapsed dramatically in the early 1990s and have since shown little sign of recovery. Many experienced dramatic increases in natural mortality, ostensibly attributable in some populations to increased predation by seals. Our findings show that increased natural mortality of a magnitude observed for overfished cod stocks has been more than sufficient to fundamentally alter the dynamics of density-dependent population regulation. The demographic Allee effect generated by these changes can slow down or even impede the recovery of depleted populations even in the absence of fishing.

Atlantic salmon brood stock management and breeding handbook

USGS Publications Warehouse

Kincaid, Harold L.; Stanley, Jon G.

1989-01-01

Anadromus runs of Atlantic salmon have been restored to the Connecticut, Merrimack, Pawcatuck, Penobscot, and St. Croix rivers in New England by the stocking of more than 8 million smolts since 1948. Fish-breeding methods have been developed that minimize inbreeding and domestication and enhance natural selection. Methods are available to advance the maturation of brood stock, control the sex of production lots and store gametes. Current hatchery practices emphasize the use of sea-run brood stock trapped upon return to the rivers and a limited number of captive brood stock and rejuvenated kelts. Fish are allowed to mature naturally, after which they are spawned and incubated artificially. Generally, 1-year smolts are produced, and excess fish are stocked as fry in headwater streams. Smolts are stocked during periods of rising water in spring. Self-release pools are planned that enable smolts to choose the emigration time. Culturists keep good records that permit evaluation of the performance of strains and the effects of breeding practices. As Atlantic salmon populations expand, culturists must use sound breeding methods that enhance biotic potential while maintaining genetic diversity and protecting unique gene pools.

Dynamics of fish diseases in the lower Elbe River

NASA Astrophysics Data System (ADS)

Möller, H.

1984-03-01

As part of a survey on population dynamics and ecology of fishesin the Elbe River, seasonal and regional fluctuations of external fish diseases were studied from the open North Sea to Hamburg in 1981 1982. Clinical signs of 11 different diseases, several of them not being recorded before, were noted in 22 fish species. Averaged over all samples, the total disease prevalence was below 1 % in 16 species. Highest prevalences were found in smelt (12.7 %), eel (9.2 %), and flounder (5.5 %). The frequency of most diseases increased in larger (older) fish. High prevalences of skeletal abnormalities in cod could be related to abnormal migration habits of diseased fish. Spawning papillomatosis, skin ulceration, and fin rot in smelt occurred predominantly during the spawning season. Most diseases observed occurred at relatively high prevalences in the central Elbe estuary between Cuxhaven and Brunsbüttel. This is most obvious for lymphocystis, fin rot, skin ulceration, and bleaching syndrome in flounder, but such a tendency also seems to occur in cauliflower disease of eel, as well as spawning papillomatosis and pharyngeal granuloma in smelt. This area is less heavily polluted and less frequently affected by oxygen deficiency than the area upstream of Glückstadt, where diseases in general occurred at lower frequencies. Therefore, it is concluded that neither pollution nor lack of oxygen are the main triggers for the outbreak of diseases in Elbe fish. It is supposed that large tidal fluctuations of salinity are a major stress factor for fish in the estuary between Cuxhaven and Brunsbüttel. Flounder from this area usually are in a relatively bad nutritional state. Their condition factor increases significantly towards Hamburg, while their disease prevalence decreases in the same direction.

Environmental change influences the life history of salmon Salmo salar in the North Atlantic Ocean.

PubMed

Jonsson, B; Jonsson, N; Albretsen, J

2016-02-01

Annual mean total length (LT) of wild one-sea-winter (1SW) Atlantic salmon Salmo salar of the Norwegian River Imsa decreased from 63 to 54 cm with a corresponding decrease in condition factor (K) for cohorts migrating to sea from 1976 to 2010. The reduction in LT is associated with a 40% decline in mean individual mass, from 2 to 1·2 kg. Hatchery fish reared from parental fish of the same population exhibited similar changes from 1981 onwards. The decrease in LT correlated negatively with near-surface temperatures in the eastern Norwegian Sea, thought to be the main feeding area of the present stock. Furthermore, S. salar exhibited significant variations in the proportion of cohorts attaining maturity after only one winter in the ocean. The proportion of S. salar spawning as 1SW fish was lower both in the 1970s and after 2000 than in the 1980s and 1990s associated with a gradual decline in post-smolt growth and smaller amounts of reserve energy in the fish. In wild S. salar, there was a positive association between post-smolt growth and the sea survival back to the River Imsa for spawning. In addition, among smolt year-classes, there were significant positive correlations between wild and hatchery S. salar in LT, K and age at maturity. The present changes may be caused by ecosystem changes following the collapse and rebuilding of the pelagic fish abundance in the North Atlantic Ocean, a gradual decrease in zooplankton abundance and climate change with increasing surface temperature in the Norwegian Sea. Thus, the observed variation in the life-history traits of S. salar appears primarily associated with major changes in the pelagic food web in the ocean. © 2016 The Fisheries Society of the British Isles.

Transcriptional responses in juvenile Atlantic cod (Gadus morhua) after exposure to mercury-contaminated sediments obtained near the wreck of the German WW2 submarine U-864, and from Bergen Harbor, Western Norway.

PubMed

Olsvik, Pål A; Brattås, Marianne; Lie, Kai K; Goksøyr, Anders

2011-04-01

The main aim of the present work was to investigate the effects of mercury (Hg)-enriched sediments on fish. Sediments near the sunken German WW2 submarine U-864, which according to historical documents included 67 tons of metallic Hg in its cargo, are enriched of Hg leaking from the wreckage. Juvenile Atlantic cod (Gadus morhua) were exposed to two field-collected polluted sediments (U-864: inorganic Hg and Bergen Harbor (Vågen): inorganic Hg, PCB and PAH) or two comparable reference sediments for 5 weeks in the laboratory, and transcriptional responses evaluated in gills and liver. Gills of fish exposed to the Hg-enriched sunken WW2 submarine U-864 sediment contained four fold higher Hg levels compared to the control fish. An increase in Hg content in liver in the U-864 fish was also observed. The transcriptional results showed that calreticulin, HSP70 and heme oxygenase mRNA were significantly up-regulated in gills in fish exposed to the Hg-enriched sediments, whereas calreticulin, heme oxygenase, transferrin and WAP65 were significantly up-regulated and glutathione peroxidase 4B and zona pellucida 3 were significantly down-regulated in liver tissue. In gills and liver of cod exposed to the mixed-contaminated Vågen sediment, CYP1A showed the highest induction. In conclusion, the experiment shows that sediment-bound Hg is available to the fish and affects the transcription of oxidative stress responsive enzymes, suggesting that the Hg-enriched sediments may negatively affect the local wildlife. Furthermore, the mixed contaminated sediments of Vågen affected similar responses in addition to Ah-receptor mediated responses reflecting exposure to PAHs and PCBs. Copyright © 2010 Elsevier Ltd. All rights reserved.

Adjustments of molecular key components of branchial ion and pH regulation in Atlantic cod (Gadus morhua) in response to ocean acidification and warming.

PubMed

Michael, Katharina; Kreiss, Cornelia M; Hu, Marian Y; Koschnick, Nils; Bickmeyer, Ulf; Dupont, Sam; Pörtner, Hans-O; Lucassen, Magnus

2016-03-01

Marine teleost fish sustain compensation of extracellular pH after exposure to hypercapnia by means of efficient ion and acid-base regulation. Elevated rates of ion and acid-base regulation under hypercapnia may be stimulated further by elevated temperature. Here, we characterized the regulation of transepithelial ion transporters (NKCC1, NBC1, SLC26A6, NHE1 and 2) and ATPases (Na(+)/K(+) ATPase and V-type H(+) ATPase) in gills of Atlantic cod (Gadus morhua) after 4 weeks of exposure to ambient and future PCO2 levels (550 μatm, 1200 μatm, 2200 μatm) at optimum (10 °C) and summer maximum temperature (18 °C), respectively. Gene expression of most branchial ion transporters revealed temperature- and dose-dependent responses to elevated PCO2. Transcriptional regulation resulted in stable protein expression at 10 °C, whereas expression of most transport proteins increased at medium PCO2 and 18 °C. mRNA and protein expression of distinct ion transport proteins were closely co-regulated, substantiating cellular functional relationships. Na(+)/K(+) ATPase capacities were PCO2 independent, but increased with acclimation temperature, whereas H(+) ATPase capacities were thermally compensated but decreased at medium PCO2 and 10 °C. When functional capacities of branchial ATPases were compared with mitochondrial F1Fo ATP-synthase strong correlations of F1Fo ATP-synthase and ATPase capacities generally indicate close coordination of branchial aerobic ATP demand and supply. Our data indicate physiological plasticity in the gills of cod to adjust to a warming, acidifying ocean within limits. In light of the interacting and non-linear, dose-dependent effects of both climate factors the role of these mechanisms in shaping resilience under climate change remains to be explored. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Influences of large- and regional-scale climate on fish recruitment in the Skagerrak-Kattegat over the last century

NASA Astrophysics Data System (ADS)

Linderholm, Hans W.; Cardinale, Massimiliano; Bartolino, Valerio; Chen, Deliang; Ou, Tinghai; Svedäng, Henrik

2014-06-01

Dynamics of commercial fish stocks are generally associated with fishing pressure and climate variability. Due to short time series, past studies of the relationships between fish stock dynamics and climate have mainly been restricted to the last few decades. Here we analyzed a century-long time series of plaice, cod and haddock from the Skagerrak-Kattegat, to assess the long-term influence of climate on recruitment. Recruitment success (RS) was compared against sea-surface temperature (SST) and atmospheric circulation indices on large (North Atlantic) and regional (Skagerrak-Kattegat) scales. Our results show that the influence of climate on RS was more pronounced on longer, than on shorter timescales. Over the century-long period, a shift from low to high climate sensitivity was seen from the early to the late part for plaice and cod, while the opposite was found for haddock. This shift suggests that the increasing fishing pressure and the climate change in the Skagerrak-Kattegat have resulted in an increased sensitivity of RS to climate for plaice and cod. The diminishing of climate sensitivity in haddock RS, on the other hand, may be linked to the early twentieth century collapse of the stock in the region. While no long-term relationship between RS and the Atlantic Multidecadal Oscillation (AMO) could be found, large RS fluctuations during the positive phase of the AMO (1935-1960), relative to the cold phases, suggests a changed pattern in recruitment during warm periods. On the other hand, this could be due to the increased fishing pressure in the area. Thus, reported correlations between climate and fish may be caused by strong trends in climate in the late-twentieth century, and coincident reduction in fish stocks caused by intense fishing, rather than a stable relationship between climate and fish recruitment per se.

Potential impact of climate change on the Intra-Americas Sea: Part 2. Implications for Atlantic bluefin tuna and skipjack tuna adult and larval habitats

NASA Astrophysics Data System (ADS)

Muhling, Barbara A.; Liu, Yanyun; Lee, Sang-Ki; Lamkin, John T.; Roffer, Mitchell A.; Muller-Karger, Frank; Walter, John F., III

2015-08-01

Increasing water temperatures due to climate change will likely have significant impacts on distributions and life histories of Atlantic tunas. In this study, we combined predictive habitat models with a downscaled climate model to examine potential impacts on adults and larvae of Atlantic bluefin tuna (Thunnus thynnus) and skipjack tuna (Katsuwonus pelamis) in the Intra-Americas Sea (IAS). An additional downscaled model covering the 20th century was used to compare habitat fluctuations from natural variability to predicted future changes under two climate change scenarios: Representative Concentration Pathway (RCP) 4.5 (medium-low) and RCP 8.5 (high). Results showed marked temperature-induced habitat losses for both adult and larval bluefin tuna on their northern Gulf of Mexico spawning grounds. In contrast, habitat suitability for skipjack tuna increased as temperatures warmed. Model error was highest for the two skipjack tuna models, particularly at higher temperatures. This work suggests that influences of climate change on highly migratory Atlantic tuna species are likely to be substantial, but strongly species-specific. While impacts on fish populations remain uncertain, these changes in habitat suitability will likely alter the spatial and temporal availability of species to fishing fleets, and challenge equilibrium assumptions of environmental stability, upon which fisheries management benchmarks are based.

Alternative reproductive tactics increase effective population size and decrease inbreeding in wild Atlantic salmon

PubMed Central

Perrier, Charles; Normandeau, Éric; Dionne, Mélanie; Richard, Antoine; Bernatchez, Louis

2014-01-01

While nonanadromous males (stream-resident and/or mature male parr) contribute to reproduction in anadromous salmonids, little is known about their impacts on key population genetic parameters. Here, we evaluated the contribution of Atlantic salmon mature male parr to the effective number of breeders (Nb) using both demographic (variance in reproductive success) and genetic (linkage disequilibrium) methods, the number of alleles, and the relatedness among breeders. We used a recently published pedigree reconstruction of a wild anadromous Atlantic salmon population in which 2548 fry born in 2010 were assigned parentage to 144 anadromous female and 101 anadromous females that returned to the river to spawn in 2009 and to 462 mature male parr. Demographic and genetic methods revealed that mature male parr increased population Nb by 1.79 and 1.85 times, respectively. Moreover, mature male parr boosted the number of alleles found among progenies. Finally, mature male parr were in average less related to anadromous females than were anadromous males, likely because of asynchronous sexual maturation between mature male parr and anadromous fish of a given cohort. By increasing Nb and allelic richness, and by decreasing inbreeding, the reproductive contribution of mature male parr has important evolutionary and conservation implications for declining Atlantic salmon populations. PMID:25553070

Are Atlantic cod in Store Lungegårdsvann, a seawater recipient in Bergen, affected by environmental contaminants? A qRT-PCR survey.

PubMed

Olsvik, Pål A; Lie, Kai K; Goksøyr, Anders; Midtun, Torbjørn; Frantzen, Sylvia; Maage, Amund

2009-01-01

The aim of this study was to examine the transcriptional levels of selected genes in liver and head kidney of Atlantic cod Gadus morhua sampled in Store Lungegårdsvann, a seawater recipient situated in the middle of the city of Bergen, Norway, for effects of contaminants released from municipal sewage effluents and former dump sites. Five males and six females were caught with fish traps in Store Lungegårdsvann in 2006. Cod from a location near Jondal in the Hardanger Fjord were used as controls (five males and four females). The following 12 genes were picked as potential markers of contaminant exposure: cytochrome P-450 1A (CYP1A), cytochrome P-450 2C33-like (CYP2C33-like), cytochrome P-450 3C (CYP3C), glutathione S-transcriptase pi (GST) (detoxification and biotransformation), Mn superoxide dismutase (Mn SOD), glutathione reductase (GR), heat-shock protein 70 (HSP70) (oxidative stress), vitellogenin A (VtgA), vitellogenin B (VtgB), zona pellucida 2 (ZP2) (effects of estrogen disruptors), B-cell lymphoma 2 (Bcl-2), and cyclin-dependent kinase inhibitor 1A (CDKN1A) (radiation). The results showed that two males caught in Store Lungegårdsvann possessed high transcriptional levels of VtgA, VtgB, and ZP2 mRNA in the liver. In addition, CYP1A was 4.9-fold higher expressed in males from Store Lungegårdsvann compared to males from the reference population. CYP2C33-like mRNA expression was significantly higher (1.8-fold) in females from Store Lungegårdsvann than in females from the reference population. CYP1A was significantly lower (4.7-fold) expressed in head kidney of females from Store Lungegårdsvann than in females from Hardanger Fjord. In a follow-up examination with sexually mature cod sampled in Store Lungegårdsvann in 2007, the livers were shown to contain high levels of polychlorinated biphenyls (PCB) and dioxin-like PCB. In conclusion, fish inhabiting Store Lungegårdsvann are exposed not only to endocrine disruptors but also to other contaminants that affect the transcription of phase I biotransformation genes.

Dispersal Routes and Habitat Utilization of Juvenile Atlantic Bluefin Tuna, Thunnus thynnus, Tracked with Mini PSAT and Archival Tags

PubMed Central

Galuardi, Benjamin; Lutcavage, Molly

2012-01-01

Between 2005 and 2009, we deployed 58 miniature pop-up satellite archival tags (PSAT) and 132 implanted archival tags on juvenile Atlantic bluefin tuna (age 2–5) in the northwest Atlantic Ocean. Data returned from these efforts (n = 26 PSATs, 1 archival tag) revealed their dispersal routes, horizontal and vertical movements and habitat utilization. All of the tagged bluefin tuna remained in the northwest Atlantic for the duration observed, and in summer months exhibited core-use of coastal seas extending from Maryland to Cape Cod, MA, (USA) out to the shelf break. Their winter distributions were more spatially disaggregated, ranging south to the South Atlantic Bight, northern Bahamas and Gulf Stream. Vertical habitat patterns showed that juvenile bluefin tuna mainly occupied shallow depths (mean  = 5–12 m, sd  = 15–23.7 m) and relatively warm water masses in summer (mean  = 17.9–20.9°C, sd  = 4.2–2.6°C) and had deeper and more variable depth patterns in winter (mean  = 41–58 m, sd  = 48.9–62.2 m). Our tagging results reveal annual dispersal patterns, behavior and oceanographic associations of juvenile Atlantic bluefin tuna that were only surmised in earlier studies. Fishery independent profiling from electronic tagging also provide spatially and temporally explicit information for evaluating dispersals rates, population structure and fisheries catch patterns. PMID:22629461

Life cycle ecophysiology of small pelagic fish and climate-driven changes in populations

NASA Astrophysics Data System (ADS)

Peck, Myron A.; Reglero, Patricia; Takahashi, Motomitsu; Catalán, Ignacio A.

2013-09-01

Due to their population characteristics and trophodynamic role, small pelagic fishes are excellent bio-indicators of climate-driven changes in marine systems world-wide. We argue that making robust projections of future changes in the productivity and distribution of small pelagics will require a cause-and-effect understanding of historical changes based upon physiological principles. Here, we reviewed the ecophysiology of small pelagic (clupeiform) fishes including a matrix of abiotic and biotic extrinsic factors (e.g., temperature, salinity, light, and prey characteristics) and stage-specific vital rates: (1) adult spawning, (2) survival and development of eggs and yolk sac larvae, and (3) feeding and growth of larvae, post-larvae and juveniles. Emphasis was placed on species inhabiting Northwest Pacific and Northeast Atlantic (European) waters for which summary papers are particularly scarce compared to anchovy and sardine in upwelling systems. Our review revealed that thermal niches (optimal and sub-optimal ranges in temperatures) were species- and stage-specific but that temperature effects only partly explained observed changes in the distribution and/or productivity of populations in the Northwest Pacific and Northeast Atlantic; changes in temperature may be necessary but not sufficient to induce population-level shifts. Prey availability during the late larval and early juvenile period was a common, density-dependent mechanism linked to fluctuations in populations but recruitment mechanisms were system-specific suggesting that generalizations of climate drivers across systems should be avoided. We identified gaps in knowledge regarding basic elements of the growth physiology of each life stage that will require additional field and laboratory study. Avenues of research are recommended that will aid the development of models that provide more robust, physiological-based projections of the population dynamics of these and other small pelagic fish. In our opinion, the continued development of biophysical models that close the life cycle (depict all life stages) offers the best chance of revealing processes causing historical fluctuations on the productivity and distribution of small pelagic fishes and to project future climate-driven impacts. Correctly representing physiological-based mechanisms will increase confidence in the outcomes of models simulating the potential impacts of bottom-up processes, a first step towards evaluating the mixture of factors and processes (e.g. intra-guild dynamics, predation, fisheries exploitation) which interact with climate to affect populations of small pelagic fishes. Understand the impacts of reduced growth rates during the juvenile stage on the process of maturation and spawning condition of small pelagic fishes. Examine the effects of changes in prey quality on the duration and magnitude of spawning by small pelagic fishes to capture how climate-driven changes in zooplankton species composition might act as a “bottom-up” regulator of fish productivity. Identify the drivers for spawning location and timing to better understand how spawning dynamics may be influenced by climate change (e.g. changes in water salinity or turbidity resulting from changes in river discharges or wind-driven turbulence, respectively).

Baltic Eye: Focusing on Science and Communication to Improve Policy Making for the Baltic Sea Environment

NASA Astrophysics Data System (ADS)

McCrackin, M. L.

2016-12-01

In order to better communicate relevant scientific knowledge to policy- and decision makers, Stockholm University and the Baltic Sea 2020 Foundation partnered to create Baltic Eye in 2014. Seven scientists and two communicators constitute the core team of this initiative. The team integrates communications with scientific analysis and synthesis of Baltic Sea environmental issues. In the past year, the team has focused on two main issues: fisheries management and microplastics. Baltic Sea cod stocks are in poor condition, with large numbers of small individuals. Baltic Eye recommended improvements to the European Union's multiannual fisheries plan to better align with ecosystem-based management principles: prioritization of cod stock recovery, greater consideration of natural variability of temperature and salinity (which affects cod spawning success), and inclusion of mechanisms to adjust quotas in the event of major environmental changes. Communications included policy briefs and debate articles targeted to the European Parliament, national government ministries, and non-governmental organizations. Every year, up to 40 tons of microplastics from personal care products are released in the Baltic Sea catchment. Baltic Eye raised awareness of the issue and made recommended ways to reduce microplastic emissions. Communications included a public presentation to journalists, politicians, and representatives of Swedish government ministries. A policy brief was provided Heads of Delegates of the Helsinki Commission (for protrection of the Baltic Sea environment) in advance of a meeting to develop a plan of action for marine litter. Researchers were interviewed for radio, TV, and print media in Sweden, Finland, and Germany. Next steps are to engage with multinational manufacturers about plans to voluntarily phase out microplastics in personal care products.

Baltic Eye: Focusing on Science and Communication to Improve Policy Making for the Baltic Sea Environment

NASA Astrophysics Data System (ADS)

McCrackin, M. L.

2016-02-01

In order to better communicate relevant scientific knowledge to policy- and decision makers, Stockholm University and the Baltic Sea 2020 Foundation partnered to create Baltic Eye in 2014. Seven scientists and two communicators constitute the core team of this initiative. The team integrates communications with scientific analysis and synthesis of Baltic Sea environmental issues. In the past year, the team has focused on two main issues: fisheries management and microplastics. Baltic Sea cod stocks are in poor condition, with large numbers of small individuals. Baltic Eye recommended improvements to the European Union's multiannual fisheries plan to better align with ecosystem-based management principles: prioritization of cod stock recovery, greater consideration of natural variability of temperature and salinity (which affects cod spawning success), and inclusion of mechanisms to adjust quotas in the event of major environmental changes. Communications included policy briefs and debate articles targeted to the European Parliament, national government ministries, and non-governmental organizations. Every year, up to 40 tons of microplastics from personal care products are released in the Baltic Sea catchment. Baltic Eye raised awareness of the issue and made recommended ways to reduce microplastic emissions. Communications included a public presentation to journalists, politicians, and representatives of Swedish government ministries. A policy brief was provided Heads of Delegates of the Helsinki Commission (for protrection of the Baltic Sea environment) in advance of a meeting to develop a plan of action for marine litter. Researchers were interviewed for radio, TV, and print media in Sweden, Finland, and Germany. Next steps are to engage with multinational manufacturers about plans to voluntarily phase out microplastics in personal care products.

Reproductive biology of the black coral Antipathella wollastoni (Cnidaria: Antipatharia) in the Azores (NE Atlantic)

NASA Astrophysics Data System (ADS)

Rakka, Maria; Orejas, Covadonga; Sampaio, Iris; Monteiro, João; Parra, Hugo; Carreiro-Silva, Marina

2017-11-01

Antipathella wollastoni is an antipatharian species common to Macaronesia, occurring in depths between 20 and 1425 m. Despite its importance as a habitat-forming species, there is no information about its basic biology. The aim of the current study is to describe its reproductive strategy, gametogenic cycle and reproductive timing. Sampling was performed monthly on six tagged colonies during one year and specimens were histologically processed. A. wollastoni was found to be a gonochoric broadcast spawner. Gametogenesis took place within the primary transversal mesenteries, and followed an annual cycle. The reproductive season coincided with an increase in seawater temperature but spawning, inferred from the disappearance of gametes, likely happened after the sea surface temperature peak of the year (September 2009). Polyp fecundity ranged from 1 to 309 oocytes/polyp. A decrease in polyp fecundity was detected in samples at the higher pre-spawning maturity stage, indicating possible repetitive spawning or oocyte absorption. Intra-colonial comparisons revealed a longer duration of the reproductive cycle in the medial colony section, and a gradient of increased oocyte size towards the apical section, possibly due to intra-colonial differences in energy allocation between reproduction and other biological processes, or as a strategy against predation on gametes/larvae. Colony height was positively correlated with polyp fecundity indicating that the reproductive output increases with colony size.

Ecosystem Scale Acoustic Sensing Reveals Humpback Whale Behavior Synchronous with Herring Spawning Processes and Re-Evaluation Finds No Effect of Sonar on Humpback Song Occurrence in the Gulf of Maine in Fall 2006

PubMed Central

Gong, Zheng; Jain, Ankita D.; Tran, Duong; Yi, Dong Hoon; Wu, Fan; Zorn, Alexander; Ratilal, Purnima; Makris, Nicholas C.

2014-01-01

We show that humpback-whale vocalization behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of Maine. With a passive, wide-aperture, densely-sampled, coherent hydrophone array towed north of Georges Bank in a Fall 2006 Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment, vocalizing whales could be instantaneously detected and localized over most of the Gulf of Maine ecosystem in a roughly 400-km diameter area by introducing array gain, of 18 dB, orders of magnitude higher than previously available in acoustic whale sensing. With humpback-whale vocalizations consistently recorded at roughly 2000/day, we show that vocalizing humpbacks (i) were overwhelmingly distributed along the northern flank of Georges Bank, coinciding with the peak spawning time and location of Atlantic herring, and (ii) their overall vocalization behavior was strongly diurnal, synchronous with the formation of large nocturnal herring shoals, with a call rate roughly ten-times higher at night than during the day. Humpback-whale vocalizations were comprised of (1) highly diurnal non-song calls, suited to hunting and feeding behavior, and (2) songs, which had constant occurrence rate over a diurnal cycle, invariant to diurnal herring shoaling. Before and during OAWRS survey transmissions: (a) no vocalizing whales were found at Stellwagen Bank, which had negligible herring populations, and (b) a constant humpback-whale song occurrence rate indicates the transmissions had no effect on humpback song. These measurements contradict the conclusions of Risch et al. Our analysis indicates that (a) the song occurrence variation reported in Risch et al. is consistent with natural causes other than sonar, (b) the reducing change in song reported in Risch et al. occurred days before the sonar survey began, and (c) the Risch et al. method lacks the statistical significance to draw the conclusions of Risch et al. because it has a 98–100% false-positive rate and lacks any true-positive confirmation. PMID:25289938

Removal of small dams and its influence on physical habitat for salmonids in a Norwegian river

NASA Astrophysics Data System (ADS)

Fjeldstad, Hans-Petter; Barlaup, Bjørn; Stickler, Morten; Alfredsen, Knut; Gabrielsen, Sven-Erik

2010-05-01

While research and implementation of upstream migration solutions is extensive, and indeed often successful, full scale restoration projects and investigations of their influence on fish biology are rare in Norway. Acid deposition in Norwegian catchments peaked in the 1980's and resulted in both chronically and episodically acidified rivers and Salmonids in River Nidelva, one of the largest cathments in southern Norway, where extinct for decades. During this period hydropower development in the river paid limited attention to aquatic ecology. Weirs were constructed for esthetic purposes in the late 1970's and turned a 3 km stretch into a lake habitat, well suited for lake dwelling fish species, but unsuited for migration, spawning and juvenile habitat for salmonids. Since 2005, continuous liming to mitigate acidification has improved the water quality and a program for reintroduction of Atlantic salmon has been implemented. We used hydraulic modeling to plan the removal of two weirs on a bypass reach of the river. The 50 meters wide concrete weirs were blasted and removed in 2007, and ecological monitoring has been carried out in the river to assess the effect of weir removal. Topographic mapping, hydraulic measurements and modeling, in combination with biological surveys before and after the removal of the weirs, has proved to represent a powerful method for design of physical habitat adjustments and assessing their influence on fish biology. The model results also supported a rapid progress of planning and executing of the works. While telemetry studies before weir removal suggested that adult migration past the weirs was delayed with several weeks the fish can now pass the reach with minor obstacles. Spawning sites were discovered in the old bed substrate and were occupied already the first season after water velocities increased to suitable levels for spawning. Accordingly, the densities of Atlantic salmon juveniles have shown a marked increased after the conclusion of the project. Catches of pike and cyprinids on the reach is reduced, indicating that their habitat is no longer suitable, while salmon anglers have found new favorite spots in the restored pools and runs.

Ecosystem scale acoustic sensing reveals humpback whale behavior synchronous with herring spawning processes and re-evaluation finds no effect of sonar on humpback song occurrence in the Gulf of Maine in fall 2006.

PubMed

Gong, Zheng; Jain, Ankita D; Tran, Duong; Yi, Dong Hoon; Wu, Fan; Zorn, Alexander; Ratilal, Purnima; Makris, Nicholas C

2014-01-01

We show that humpback-whale vocalization behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of Maine. With a passive, wide-aperture, densely-sampled, coherent hydrophone array towed north of Georges Bank in a Fall 2006 Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment, vocalizing whales could be instantaneously detected and localized over most of the Gulf of Maine ecosystem in a roughly 400-km diameter area by introducing array gain, of 18 dB, orders of magnitude higher than previously available in acoustic whale sensing. With humpback-whale vocalizations consistently recorded at roughly 2000/day, we show that vocalizing humpbacks (i) were overwhelmingly distributed along the northern flank of Georges Bank, coinciding with the peak spawning time and location of Atlantic herring, and (ii) their overall vocalization behavior was strongly diurnal, synchronous with the formation of large nocturnal herring shoals, with a call rate roughly ten-times higher at night than during the day. Humpback-whale vocalizations were comprised of (1) highly diurnal non-song calls, suited to hunting and feeding behavior, and (2) songs, which had constant occurrence rate over a diurnal cycle, invariant to diurnal herring shoaling. Before and during OAWRS survey transmissions: (a) no vocalizing whales were found at Stellwagen Bank, which had negligible herring populations, and (b) a constant humpback-whale song occurrence rate indicates the transmissions had no effect on humpback song. These measurements contradict the conclusions of Risch et al. Our analysis indicates that (a) the song occurrence variation reported in Risch et al. is consistent with natural causes other than sonar, (b) the reducing change in song reported in Risch et al. occurred days before the sonar survey began, and (c) the Risch et al. method lacks the statistical significance to draw the conclusions of Risch et al. because it has a 98-100% false-positive rate and lacks any true-positive confirmation.

Effect of climate change on marine ecosystems

NASA Astrophysics Data System (ADS)

Vikebo, F. B.; Sundby, S.; Aadlandsvik, B.; Fiksen, O.

2003-04-01

As a part of the INTEGRATION project, headed by Potsdam Institute for Climate Impact Research, funded by the German Research Council, the impact of climate change scenarios on marine fish populations will be addressed on a spesific population basis and will focus on fish populations in the northern North Atlantic with special emphasis on cod. The approach taken will mainly be a modelling study supported by analysis of existing data on fish stocks and climate. Through down-scaling and nesting techniques, various climate change scenarios with reduced THC in the North Atlantic will be investigated with higher spatial resolution for selected shelf areas. The hydrodynamical model used for the regional ocean modeling is ROMS (http://marine.rutgers.edu/po/models/roms/). An individual based model will be implemented into the larval drift module to simulate growth of the larvae along the drift paths.

Comparative ecology of widely distributed pelagic fish species in the North Atlantic: Implications for modelling climate and fisheries impacts

NASA Astrophysics Data System (ADS)

Trenkel, V. M.; Huse, G.; MacKenzie, B. R.; Alvarez, P.; Arrizabalaga, H.; Castonguay, M.; Goñi, N.; Grégoire, F.; Hátún, H.; Jansen, T.; Jacobsen, J. A.; Lehodey, P.; Lutcavage, M.; Mariani, P.; Melvin, G. D.; Neilson, J. D.; Nøttestad, L.; Óskarsson, G. J.; Payne, M. R.; Richardson, D. E.; Senina, I.; Speirs, D. C.

2014-12-01

This paper reviews the current knowledge on the ecology of widely distributed pelagic fish stocks in the North Atlantic basin with emphasis on their role in the food web and the factors determining their relationship with the environment. We consider herring (Clupea harengus), mackerel (Scomber scombrus), capelin (Mallotus villosus), blue whiting (Micromesistius poutassou), and horse mackerel (Trachurus trachurus), which have distributions extending beyond the continental shelf and predominantly occur on both sides of the North Atlantic. We also include albacore (Thunnus alalunga), bluefin tuna (Thunnus thynnus), swordfish (Xiphias gladius), and blue marlin (Makaira nigricans), which, by contrast, show large-scale migrations at the basin scale. We focus on the links between life history processes and the environment, horizontal and vertical distribution, spatial structure and trophic role. Many of these species carry out extensive migrations from spawning grounds to nursery and feeding areas. Large oceanographic features such as the North Atlantic subpolar gyre play an important role in determining spatial distributions and driving variations in stock size. Given the large biomasses of especially the smaller species considered here, these stocks can exert significant top-down pressures on the food web and are important in supporting higher trophic levels. The review reveals commonalities and differences between the ecology of widely distributed pelagic fish in the NE and NW Atlantic basins, identifies knowledge gaps and modelling needs that the EURO-BASIN project attempts to address.

Productivity responses of a widespread marine piscivore, Gadus morhua, to oceanic thermal extremes and trends.

PubMed

Mantzouni, Irene; MacKenzie, Brian R

2010-06-22

Climate change will have major consequences for population dynamics and life histories of marine biota as it progresses in the twenty-first century. These impacts will differ in magnitude and direction for populations within individual marine species whose geographical ranges span large gradients in latitude and temperature. Here we use meta-analytical methods to investigate how recruitment (i.e. the number of new fish produced by spawners in a given year which subsequently grow and survive to become vulnerable to fishing gear) has reacted to temperature fluctuations, and in particular to extremes of temperature, in cod populations throughout the north Atlantic. Temperature has geographically explicit effects on cod recruitment. Impacts differ depending on whether populations are located in the upper (negative effects) or in the lower (positive effects) thermal range. The probabilities of successful year-classes in populations living in warm areas is on average 34 per cent higher in cold compared with warm seasons, whereas opposite patterns exist for populations living in cold areas. These results have implications for cod dynamics, distributions and phenologies under the influence of ocean warming, particularly related to not only changes in the mean temperature, but also its variability (e.g. frequency of exceptionally cold or warm seasons).

Variability of sea-surface temperature in the South Atlantic bight as observed from satellite: Implications for offshore-spawning fish

NASA Astrophysics Data System (ADS)

Stegmann, P. M.; Yoder, J. A.

1996-06-01

We examined full-resolution (1 × 1 km) satellite images of sea-surface temperature (SST) over five consecutive years (1981-1986) covering the Atlantic menhaden ( Brevoortia tyrannus) recruitment period (November-April) in the SABRE (South Atlantic Bight recruitment experiment) study site. The results of our image time series indicated two processes which could be possible mechanisms for the onshore transport of fish larvae into coastal regions. One is the influx of warm Gulf Stream water that oscillates in and out of the Carolina Bays. These oscillations occurred throughout the study period over distances of 20-40 km and on time-scales as short as two days. The other is a tongue of relatively cold water located adjacent to the Virginia coast that moved southward and penetrated into Onslow Bay between January and March. Previous studies showed that Atlantic menhaden preferentially spawn in 18-22°C waters on the outer shelf. On the assumption that the 18°C isotherm (18DI) indicates where high larval abundance may occur, we used AVHRR-SST imagery to track the onshore-offshore movement of the 18DI along a transect extending onshore-offshore in Onslow Bay. Owing to seasonal warming and cooling, this isotherm was always found closest to the coast in early November, reached maximum offshore displacement by January/March, and then moved onshore again in April/May. Our results also showed that the position of this isotherm can move offshore or onshore in a matter of a few days. An important influence and possibly the major cause of the higher frequency displacements of the 18DI are Gulf Stream meanders or filaments moving through Onslow Bay. Our estimates of onshore isotherm speeds as determined from satellite SST ranged from 2 to 25 cm s -1 and are within the same order as those calculated by physical models or larval age determinations. If the onshore pulses of warm Gulf Stream water are indeed a mode by which menhaden larvae are transported cross-shelf, then the use of satellite-based observations to determine their frequency and onshore extent, as done in the present study, is a useful tool to study variations in fish recruitment.

Habitat selection and quality for multiple cohorts of young-of-the-year bluefish ( Pomatomus saltatrix): Comparisons between estuarine and ocean beaches in southern New Jersey

NASA Astrophysics Data System (ADS)

Taylor, David L.; Nichols, Ryan S.; Able, Kenneth W.

2007-07-01

In this study, seasonal and annual variability in the use of estuarine and ocean beaches by young-of-the-year bluefish, Pomatomus saltatrix, was evaluated by indices of abundance in coastal areas of southern New Jersey (1998-2000). Biological and physical factors measured at specific sites were correlated with bluefish abundance to determine the mechanisms underlying habitat selection. In addition, integrative and discrete indicators of bluefish growth were used to examine spatio-temporal dynamics in habitat quality and its effect on habitat selection by multiple cohorts of bluefish. Intra-annual recruitment to coastal areas of southern New Jersey was episodic, and resulted from the ingress of spring-spawned bluefish (hatch-date ˜April) to estuarine beaches in late May to early June, followed by the recruitment of summer-spawned fish (hatch-date ˜early July) to ocean beaches from July to October. Bluefish utilized estuarine and ocean beaches in a facultative manner that was responsive to dynamics in prey composition and temperature conditions. The recruitment and residency of bluefish in the estuary (1998-1999) and ocean beaches (1998), for example, was coincidental with the presence of the Atlantic silverside Menidia menidia and bay anchovy Anchoa mitchilli, the principal prey species for bluefish occupying these respective habitat-types. Bluefish abundance in the estuary (2000) and ocean beaches (1999-2000) was also correlated with water temperature, with the greatest catches of juveniles coinciding with their optimal growth temperature (24 °C). Bluefish growth, estimated as the slope of age-length relationships and daily specific growth rates, equaled 1.27-2.63 mm fork length (FL) d -1 and 3.8-8.7% body length increase d -1, respectively. The growth of sagittal otoliths was also used as a proxy for changes in bluefish size during and shortly before their time of capture. Accordingly, otolith growth rates of summer-spawned bluefish were greater at ocean beaches relative to the estuary and were explained by the more suitable temperature conditions found at ocean beaches during the mid- to late summer. Notwithstanding the fast growth of oceanic summer-spawned bluefish, individuals spawned in the spring were still larger in absolute body size at the end of the summer growing season (˜240 and 50-200 mm FL for spring- and summer-spawned bluefish, respectively). The size discrepancy between spring- and summer-spawned bluefish at the onset of autumn migrations and during overwintering periods may account for the differential recruitment success of the respective cohorts.

Local overfishing may be avoided by examining parameters of a spatio-temporal model

PubMed Central

Shackell, Nancy; Mills Flemming, Joanna

2017-01-01

Spatial erosion of stock structure through local overfishing can lead to stock collapse because fish often prefer certain locations, and fisheries tend to focus on those locations. Fishery managers are challenged to maintain the integrity of the entire stock and require scientific approaches that provide them with sound advice. Here we propose a Bayesian hierarchical spatio-temporal modelling framework for fish abundance data to estimate key parameters that define spatial stock structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape). The consideration of these spatial parameters in the stock assessment process can help identify the erosion of structure and assist in preventing local overfishing. We use Atlantic cod (Gadus morhua) in eastern Canada as a case study an examine the behaviour of these parameters from the height of the fishery through its collapse. We identify clear signals in parameter behaviour under circumstances of destructive stock erosion as well as for recovery of spatial structure even when combined with a non-recovery in abundance. Further, our model reveals the spatial pattern of areas of high and low density persists over the 41 years of available data and identifies the remnant patches. Models of this sort are crucial to recovery plans if we are to identify and protect remaining sources of recolonization for Atlantic cod. Our method is immediately applicable to other exploited species. PMID:28886179

Local overfishing may be avoided by examining parameters of a spatio-temporal model.

PubMed

Carson, Stuart; Shackell, Nancy; Mills Flemming, Joanna

2017-01-01

Spatial erosion of stock structure through local overfishing can lead to stock collapse because fish often prefer certain locations, and fisheries tend to focus on those locations. Fishery managers are challenged to maintain the integrity of the entire stock and require scientific approaches that provide them with sound advice. Here we propose a Bayesian hierarchical spatio-temporal modelling framework for fish abundance data to estimate key parameters that define spatial stock structure: persistence (similarity of spatial structure over time), connectivity (coherence of temporal pattern over space), and spatial variance (variation across the seascape). The consideration of these spatial parameters in the stock assessment process can help identify the erosion of structure and assist in preventing local overfishing. We use Atlantic cod (Gadus morhua) in eastern Canada as a case study an examine the behaviour of these parameters from the height of the fishery through its collapse. We identify clear signals in parameter behaviour under circumstances of destructive stock erosion as well as for recovery of spatial structure even when combined with a non-recovery in abundance. Further, our model reveals the spatial pattern of areas of high and low density persists over the 41 years of available data and identifies the remnant patches. Models of this sort are crucial to recovery plans if we are to identify and protect remaining sources of recolonization for Atlantic cod. Our method is immediately applicable to other exploited species.

Testing spatial heterogeneity with stock assessment models

PubMed Central

Eero, Margit; Silva, Alexandra; Ulrich, Clara; Pawlowski, Lionel; Holmes, Steven J.; Ibaibarriaga, Leire; De Oliveira, José A. A.; Riveiro, Isabel; Alzorriz, Nekane; Citores, Leire; Scott, Finlay; Uriarte, Andres; Carrera, Pablo; Duhamel, Erwan; Mosqueira, Iago

2018-01-01

This paper describes a methodology that combines meta-population theory and stock assessment models to gain insights about spatial heterogeneity of the meta-population in an operational time frame. The methodology was tested with stochastic simulations for different degrees of connectivity between sub-populations and applied to two case studies, North Sea cod (Gadus morua) and Northeast Atlantic sardine (Sardina pilchardus). Considering that the biological components of a population can be partitioned into discrete spatial units, we extended this idea into a property of additivity of sub-population abundances. If the additivity results hold true for putative sub-populations, then assessment results based on sub-populations will provide information to develop and monitor the implementation of finer scale/local management. The simulation study confirmed that when sub-populations are independent and not too heterogeneous with regards to productivity, the sum of stock assessment model estimates of sub-populations’ SSB is similar to the SSB estimates of the meta-population. It also showed that a strong diffusion process can be detected and that the stronger the connection between SSB and recruitment, the better the diffusion process will be detected. On the other hand it showed that weak to moderate diffusion processes are not easy to identify and large differences between sub-populations productivities may be confounded with weak diffusion processes. The application to North Sea cod and Atlantic sardine exemplified how much insight can be gained. In both cases the results obtained were sufficiently robust to support the regional analysis. PMID:29364901

Genetic comparison of viral hemorrhagic septicemia virus isolates from North America and Europe

USGS Publications Warehouse

Oshima, K.H.; Higman, K.H.; Arakawa, C.K.; de Kinkelin, P.; Jorgensen, P.E.V.; Meyers, T.R.; Winton, J.R.

1993-01-01

Viral hemorrhagic septicemia virus (VHSV) is the cdusative agent of a serious rhabdoviral d~sease of rainbow trout Oncorhynchus myklss in Europe The first isolation of the vlrus in North Amenca occurred In the fall of 1988 when it was recovered from adult chinook 0 tshawytscha and coho 0 klsutch salmon returning to 2 hatcher~es in the state of Washington, USA The following year, VHSV was isolated from adult coho salmon at 2 other hatcher~es in northwestern Washington In 1990 and 1991, VHSV was recovered from Pacific cod Gadus macrocephalus caught in Pnnce Willlam Sound, Alaska Genetic vanation among the 4 isolates from salmon and the 1990 ~solate from Pacific cod was determ~ned uslng T1 nbonuclease finqerprlnt~ng In addition, 4 d~verse isolates from Europe were lncluded for companson The North Amencan isolates of VHSV formed a slngle fingerprint group In which the 4 isolates from salmonids were h~ghly similar to each other and the isolate from Pacific cod was related but less s~milar The 4 European ~solates which included an isolate from Atlantic cod G morhua, formed a second fingerpnnt group The genetic d~vers~ty among the isolates within each fingerpnnt group was estimated to be less than 5 % whlle the North Amencan and European strains of the virus were judged to differ by more than 5% The results indicate that the North Amerlcan isolates of VHSV are not of European ongln and that the virus may be enzootic wlthin the manne environment.

Remote Sensing of Marine Life and Submerged Target Motions with Ocean Waveguide Acoustics

NASA Astrophysics Data System (ADS)

Gong, Zheng

Many species of fish that inhabit the continental shelf waters can cause significant acoustic scattering at low- to mid-frequencies due to the large impedance contrast between their air-filled swimbladders and the surrounding water. In this thesis, we investigate the acoustic resonance scattering response from distributed fish groups both experimentally and theoretically including the effects of multiple scattering, attenuation, and dispersion in a random range-dependent ocean waveguide using an instantaneous wide-area imaging system. In navy sonar operations, the biological organisms can cause high false alarm rates or missed target detections since the biological scattering can be confused with or camouflage the returns from other discrete and distributed objects, such as underwater vehicles and geologic features. From an ecological perspective, the ability to instantaneously survey fish populations distributed over wide areas is important for fisheries management. The low-frequency target strength of shoaling Atlantic herring ( Clupea harengus) in the Gulf of Maine during their Autumn 2006 spawning season is estimated from experimental data acquired simultaneously at multiple frequencies in the 300 to 1200 Hz range using (1) a low-frequency ocean acoustic waveguide remote sensing (OAWRS) system, (2) areal population density calibration with several conventional fish finding sonar (CFFS) systems, and (3) low-frequency transmission loss measurements. The OAWRS system's instantaneous imaging diameter of 100 km and regular updating enabled unaliased monitoring of fish populations over ecosystem scales including shoals of Atlantic herring containing as many as 200 million individuals, as estimated based on single scattering assumption and confirmed by concurrent trawl and CFFS sampling. The mean scattering cross-section of an individual shoaling herring is found to consistently exhibit a strong, roughly 20 dB/octave roll-off with decreasing frequency over all days of the roughly 2-week experiment, consistent with the steep roll-offs expected for sub-resonance scattering from fish with air-filled swimbladders. A numerical Monte-Carlo model is developed to determine the statistical moments of the broadband matched filtered scattered returns from fish groups spanning over multiple range and cross-range resolution cells of a waveguide remote sensing system. It uses the parabolic equation to simulate acoustic field propagation in a random range-dependent ocean waveguide. The effects of (1) multiple scattering, (2) attenuation due to scattering, and (3) fish group 3D spatial configuration on fish population density imaging are examined. The model is applied to investigate (a) population density imaging of shoaling Atlantic herring during the 2006 Gulf of Maine Experiment (GOME06) and (b) examine the wide-area imaging of sparse aggregation of ground fish species, such as Atlantic Cod, in Ipswich Bay continental shelf environment using the waveguide remote sensing system. Incoherent intensities are shown to dominate the total scattered returns from distributed fish groups making single scattering assumption valid for inferring fish areal population densities from their matched filtered scattered intensities. Multiple scattering, attenuation, fish group 3D spatial configuration, and coherent effects, such as resonance shift, sub- and super-local-maxima are found to be negligible at the imaging frequencies employed and for the herring densities observed. Similar results are obtained for the sparsely aggregated cod, but coherent effects such as the double-peak in school resonance can be prominent at much lower fish densities. Attenuation due to scattering can be significant when the fish flesh viscosity is high, especially true for cod. We also investigate approaches for instantaneous long-range passive source localization and tracking with a towed horizontal line-array in a random range-dependent ocean waveguide using passive waveguide acoustics. This is very important for many sonar applications, such as localizing and tracking underwater vehicles and vocalizing marine mammal populations. Instantaneous passive source localization applying the (1) synthetic aperture tracking, (2) array invariant, (3) bearings-only target motion analysis in modified polar coordinates via the extended Kalman filter, and (4) bearings-migration minimum mean-square error methods using measurements made on a single towed horizontal receiver array in a random range-dependent ocean waveguide are examined. These methods are employed to localize and track a vertical source array deployed in the far-field of a towed horizontal receiver array during the Gulf of Maine 2006 Experiment. The source transmitted intermittent broadband pulses in the 300--1200 Hz frequency range. All four methods are found to be comparable with average errors of between 9% to 13% in estimating the mean source positions in a wide variety of source-receiver geometries and range separations up to 20 km. In the case of a relatively stationary source, the synthetic aperture tracking outperformed the other three methods by a factor of two with only 4% error. For a moving source, the Kalman filter method yielded the best performance with 8% error. The array invariant was the best approach for localizing sources within the endfire beam of the receiver array with less than 10% error.

Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass

PubMed Central

Taylor, Nathan G.; McAllister, Murdoch K.; Lawson, Gareth L.; Carruthers, Tom; Block, Barbara A.

2011-01-01

Atlantic bluefin tuna (Thunnus thynnus) is considered to be overfished, but the status of its populations has been debated, partly because of uncertainties regarding the effects of mixing on fishing grounds. A better understanding of spatial structure and mixing may help fisheries managers to successfully rebuild populations to sustainable levels while maximizing catches. We formulate a new seasonally and spatially explicit fisheries model that is fitted to conventional and electronic tag data, historic catch-at-age reconstructions, and otolith microchemistry stock-composition data to improve the capacity to assess past, current, and future population sizes of Atlantic bluefin tuna. We apply the model to estimate spatial and temporal mixing of the eastern (Mediterranean) and western (Gulf of Mexico) populations, and to reconstruct abundances from 1950 to 2008. We show that western and eastern populations have been reduced to 17% and 33%, respectively, of 1950 spawning stock biomass levels. Overfishing to below the biomass that produces maximum sustainable yield occurred in the 1960s and the late 1990s for western and eastern populations, respectively. The model predicts that mixing depends on season, ontogeny, and location, and is highest in the western Atlantic. Assuming that future catches are zero, western and eastern populations are predicted to recover to levels at maximum sustainable yield by 2025 and 2015, respectively. However, the western population will not recover with catches of 1750 and 12,900 tonnes (the “rebuilding quotas”) in the western and eastern Atlantic, respectively, with or without closures in the Gulf of Mexico. If future catches are double the rebuilding quotas, then rebuilding of both populations will be compromised. If fishing were to continue in the eastern Atlantic at the unregulated levels of 2007, both stocks would continue to decline. Since populations mix on North Atlantic foraging grounds, successful rebuilding policies will benefit from trans-Atlantic cooperation. PMID:22174745

Waste feed from coastal fish farms: A trophic subsidy with compositional side-effects for wild gadoids

NASA Astrophysics Data System (ADS)

Fernandez-Jover, Damian; Martinez-Rubio, Laura; Sanchez-Jerez, Pablo; Bayle-Sempere, Just T.; Lopez Jimenez, Jose Angel; Martínez Lopez, Francisco Javier; Bjørn, Pål-Arne; Uglem, Ingebrigt; Dempster, Tim

2011-03-01

Aquaculture of carnivorous fish species in sea-cages typically uses artificial feeds, with a proportion of these feeds lost to the surrounding environment. This lost resource may provide a trophic subsidy to wild fish in the vicinity of fish farms, yet the physiological consequences of the consumption of waste feed by wild fish remain unclear. In two regions in Norway with intensive aquaculture, we tested whether wild saithe ( Pollachius virens) and Atlantic cod ( Gadus morhua) associated with fish farms (F assoc), where waste feed is readily available, had modified diets, condition and fatty acid (FA) compositions in their muscle and liver tissues compared to fish unassociated (UA) with farms. Stomach content analyses revealed that both cod and saithe consumed waste feed in the vicinity of farms (6-96% of their diet was composed of food pellets). This translated into elevated body and liver condition compared to fish caught distant from farms for cod at both locations and elevated body condition for saithe at one of the locations. As a consequence of a modified diet, we detected significantly increased concentrations of terrestrial-derived fatty acids (FAs) such as linoleic (18:2ω6) and oleic (18:1ω9) acids and decreased concentrations of DHA (22:6ω3) in the muscle and/or liver of F assoc cod and saithe when compared with UA fish. In addition, the ω3:ω6 ratio clearly differed between F assoc and UA fish. Linear discriminant analysis (LDA) correctly classified 97% of fish into F assoc or UA origin for both cod and saithe based on the FA composition of liver tissues, and 89% of cod and 86% of saithe into F assoc or UA origin based on the FA composition of muscle. Thus, LDA appears a useful tool for detecting the influence of fish farms on the FA composition of wild fish. Ready availability of waste feed with high protein and fat content provides a clear trophic subsidy to wild fish in coastal waters, yet whether the accompanying side-effect of altered fatty acid compositions affects physiological performance or reproductive potential requires further research.

DNA barcoding coupled to HRM analysis as a new and simple tool for the authentication of Gadidae fish species.

PubMed

Fernandes, Telmo J R; Costa, Joana; Oliveira, M Beatriz P P; Mafra, Isabel

2017-09-01

This work aimed to exploit the use of DNA mini-barcodes combined with high resolution melting (HRM) for the authentication of gadoid species: Atlantic cod (Gadus morhua), Pacific cod (Gadus macrocephalus), Alaska pollock (Theragra chalcogramma) and saithe (Pollachius virens). Two DNA barcode regions, namely cytochrome c oxidase subunit I (COI) and cytochrome b (cytb), were analysed in silico to identify genetic variability among the four species and used, subsequently, to develop a real-time PCR method coupled with HRM analysis. The cytb mini-barcode enabled best discrimination of the target species with a high level of confidence (99.3%). The approach was applied successfully to identify gadoid species in 30 fish-containing foods, 30% of which were not as declared on the label. Herein, a novel approach for rapid, simple and cost-effective discrimination/clustering, as a tool to authenticate Gadidae fish species, according to their genetic relationship, is proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

A GCM Study of Responses of the Atmospheric Water Cycle of West Africa and the Atlantic to Saharan Dust Radiative Forcing

NASA Technical Reports Server (NTRS)

Lau, K. M.; Kim, K. M.; Sud, Y. C.; Walker, G. K.

2009-01-01

The responses of the atmospheric water cycle and climate of West Africa and the Atlantic to radiative forcing of Saharan dust are studied using the NASA finite volume general circulation model (fvGCM), coupled to a mixed layer ocean. We find evidence of an "elevated heat pump" (EHP) mechanism that underlines the responses of the atmospheric water cycle to dust forcing as follow. During the boreal summerr, as a result of large-scale atmospheric feedback triggered by absorbing dust aerosols, rainfall and cloudiness are ehanIed over the West Africa/Eastern Atlantic ITCZ, and suppressed over the West Atlantic and Caribbean region. Shortwave radiation absorption by dust warms the atmosphere and cools the surface, while longwave has the opposite response. The elevated dust layer warms the air over West Africa and the eastern Atlantic. As the warm air rises, it spawns a large-scale onshore flow carrying the moist air from the eastern Atlantic and the Gulf of Guinea. The onshore flow in turn enhances the deep convection over West Africa land, and the eastern Atlantic. The condensation heating associated with the ensuing deep convection drives and maintains an anomalous large-scale east-west overturning circulation with rising motion over West Africa/eastern Atlantic, and sinking motion over the Caribbean region. The response also includes a strengthening of the West African monsoon, manifested in a northward shift of the West Africa precipitation over land, increased low-level westerlies flow over West Africa at the southern edge of the dust layer, and a near surface westerly jet underneath the dust layer overr the Sahara. The dust radiative forcing also leads to significant changes in surface energy fluxes, resulting in cooling of the West African land and the eastern Atlantic, and warming in the West Atlantic and Caribbean. The EHP effect is most effective for moderate to highly absorbing dusts, and becomes minimized for reflecting dust with single scattering albedo at0.95 or higher.

Linking North Atlantic Teleconnections to Latitudinal Variability of Wave Climate Along the North American Atlantic Coast

NASA Astrophysics Data System (ADS)

Provancha, C.; Adams, P. N.; Hegermiller, C.; Storlazzi, C. D.

2015-12-01

Shoreline change via coastal erosion and accretion is largely influenced by variations in ocean wave climate. Identifying the sources of these variations is challenging because the timing of wave energy delivery varies over multiple timescales within ocean basins. We present the results of an investigation of USACE Wave Information Studies hindcast hourly wave heights, periods, and directions along the North American Atlantic coast from 1980-2012, designed to explore links between wave climate and teleconnection patterns. Trends in median and extreme significant wave heights (SWHs) demonstrate that mean monthly SWHs increased from 1 to 5 cm/yr along the roughly 3000 km reach of study area, with changes in hurricane season waves appearing to be most influential in producing the overall trends. Distributions of SWHs categorized by North Atlantic Oscillation (NAO) phase, show that positive-period NAO SWHs are greater than negative-period NAO SWHs along the entire eastern seaboard (25°N to 45°N). The most prominent wave direction off Cape Cod, MA during positive-period NAO is approximately 105°, as compared to approximately 75° during negative-period NAO. Prominent wave directions between Cape Canaveral, FL, and Savannah, GA exhibit a similar shift but during opposite phases of the NAO. The results of this analysis suggest that the atmosphere-ocean interactions associated with contrasting NAO phases can significantly change the wave climate observed offshore along the North American Atlantic coast, altering alongshore wave energy fluxes and sediment transport patterns along the coast.

Nitrogen isotopic analysis of carbonate-bound organic matter in modern and fossil fish otoliths

NASA Astrophysics Data System (ADS)

Lueders-Dumont, Jessica A.; Wang, Xingchen T.; Jensen, Olaf P.; Sigman, Daniel M.; Ward, Bess B.

2018-03-01

The nitrogen isotopic composition (δ15N) of otolith-bound organic matter (OM) is a potential source of information on dietary history of bony fishes. In contrast to the δ15N of white muscle tissue, the most commonly used tissue for ecological studies, the δ15N of otolith-bound OM (δ15Noto) provides a record of whole life history. More importantly, δ15Noto can be measured in contexts where tissue is not available, for example, in otolith archives and sedimentary deposits. The utility and robustness of otolith δ15N analysis was heretofore limited by the low N content of otoliths, which precluded the routine measurement of individual otoliths as well as the thorough cleaning of otolith material prior to analysis. Here, we introduce a new method based on oxidation to nitrate followed by bacterial conversion to N2O. The method requires 200-fold less N compared to traditional combustion approaches, allowing for thorough pre-cleaning and replicated analysis of individual otoliths of nearly any size. Long term precision of δ15Noto is 0.3‰. Using an internal standard of Atlantic cod (Gadus morhua) otoliths, we examine the parameters of the oxidative cleaning step with regard to oxidant (potassium persulfate and sodium hypochlorite), temperature, and time. We also report initial results that verify the usefulness of δ15Noto for ecological studies. For three salmonid species, left and right otoliths from the same fish are indistinguishable. We find that the δ15Noto of pink salmon (Oncorhynchus gorbuscha) is related to the size of the fish for this species. We find that intra-cohort δ15Noto standard deviation for wild pink salmon, farmed brown trout (Salmo trutta), and farmed rainbow trout (Oncorhynchus mykiss) are all 0.4‰ or less, suggesting that δ15Noto will be valuable for population-level studies. Lastly, our protocol yields reproducible data for both δ15Noto and otolith N content in 17th century Atlantic cod otoliths. We find that 17th century cod are approximately 2 ‰ higher than modern cod, arguably consistent with either the larger size of the otoliths (and thus inferred for the fish) or with changes in baseline (primary producer) δ15N in the modern coastal ocean compared to the past. All told, the results of this study bode well for the utility of otolith-bound δ15N for investigating the environment and ecology of modern and past fish.

Reproduction among protobranch bivalves of the family Nuculidae from sublittoral, bathyal, and abyssal depths off the New England coast of North America

NASA Astrophysics Data System (ADS)

Scheltema, Rudolf S.; Williams, Isabelle P.

2009-09-01

Protobranch bivalve species of the family Nuculidae pass through either a planktonic lecithotrophic larval stage or a direct non-planktonic development. Oogenesis of the three sublittoral species examined is synchronous. Deposition of egg masses by Nucula delphinodonta and spawning by Nucula annulata and Nucula proxima occur only during summer months. Among the four bathyal and abyssal species, Ennucula similis, Ennucula granulosa, Deminucula atacellana, and Brevinucula verrilli, oogenesis is asynchronous and there is no discernable pattern of periodicity of spawning. Absence of periodicity in reproduction in these deep-sea species is confirmed by examination of individuals from dredge samples taken at different times of the year. The median apparent fecundity among both sublittoral and deep-sea species is directly related to size (i.e. shell length) and age. Among the Nuculidae the median apparent fecundity is greater among sublittoral than bathyal and abyssal species. The geographic distribution of a species depends on its capacity to disperse. The dispersal of the planktonic lecithotrophic larvae of the sublittoral species N. annulata and N. proxima is limited to the continental shelf of the northwestern Atlantic by inshore bottom circulation and because these very small planktonic larvae (<2.5 mm) lack the capacity to move vertically upward through the water column into the offshore currents. On the other hand, the bathyal and abyssal species having lecithotrophic larvae have a very wide amphi-Atlantic distribution extending from 60°N to 40°S latitude along the North and South American coasts and from 55°N to ca. 19°S from off Europe southwards to the coast of West Africa as a consequence of dispersal by planktonic lecithotrophic larvae along the seafloor. The amphi-Atlantic dispersal must occur stepwise between deep-sea populations (e.g., off Greenland). Such a geographic distribution indicates a widespread dispersal and is supported by the genetic similarity that has been described between North American and western European populations of D. atacellana.

Human exposure to lead, cadmium and mercury through fish and seafood product consumption in Italy: a pilot evaluation.

PubMed

Pastorelli, A A; Baldini, M; Stacchini, P; Baldini, G; Morelli, S; Sagratella, E; Zaza, S; Ciardullo, S

2012-01-01

The presence of selected toxic heavy metals, such as cadmium (Cd), lead (Pb) and mercury (Hg), was investigated in fish and seafood products, namely, blue mussel, carpet shell clam, European squid, veined squid, deep-water rose shrimp, red mullet, European seabass, gilthead seabream, Atlantic cod, European hake, Atlantic bluefin tuna and swordfish so as to assess their human exposure through diet. Metals were detected by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and hydride generation atomic absorption spectrometry (Hg-AAS). Measurements of Cd, Pb and Hg were performed by means of analytical methods validated in compliance with UNI CEI EN ISO/IEC 17025 [2005. General requirements for the competence of testing and calibration laboratories. Milano (Italy): UNI Ente Nazionale Italiano di Unificazione]. The exposure assessment was undertaken matching the levels of Cd, Pb and total Hg with consumption data related to fish and seafood products selected for this purpose. In order to establish human health implications, the estimated weekly intakes (EWIs) for Cd, Pb and Hg were compared with the standard tolerable weekly intakes (TWI) for Cd and provisional tolerable weekly intakes (PTWIs) for Pb and Hg stipulated by the European Food Safety Authority (EFSA) and the Food and Agriculture Organization/World Health Organization (FAO/WHO) Joint Expert Committee on Food Additives (JECFA). The found metal concentrations were largely below the maximum levels (MLs) established at the European Union level with the exception of Cd. This metal exceeded the MLs in squid, red mullet, European hake and Atlantic cod. Squid and blue mussel showed the highest Pb concentrations which accounted for 60% and 10% of the MLs, respectively. Highest Hg levels were found in predatory fish. The concentrations of Hg in swordfish, Atlantic bluefin tuna and red mullet accounted for 50%, 30% and 30% of the MLs, respectively. The EWIs for Cd, Pb and Hg related to the consumption of fish and seafood products by the median of the Italian total population accounted for 20%, 1.5% and 10% of the standard TWI for Cd as well as PTWIs for Pb and Hg, respectively. Furthermore, the EWIs estimated using consumption data concerning Italian consumers did not exceed the standard TWI and PTWIs, except for Cd at 95th percentile.

Variation and temporal patterns in the composition of the surface ichthyoplankton in the southern Bay of Biscay (W. Atlantic)

NASA Astrophysics Data System (ADS)

d'Elbée, Jean; Castège, Iker; Hémery, Georges; Lalanne, Yann; Mouchès, Claude; Pautrizel, Françoise; D'Amico, Frank

2009-05-01

From September 2000 to December 2006, surface plankton samples were collected on a monthly basis, from a station located in the southern Bay of Biscay (43°37N; 1°43W France), near the deep Capbreton canyon. In this paper, the results for the ichthyoplankton assemblage are presented. Among the 62 taxa recorded, only 35 were present in the larval stage whilst only 10 were represented by their eggs. Taxa represented by both stages (eggs+larvae; N=17) had the highest abundance. The presence in the surface plankton assemblage of species, at either or both stage, is interpreted within the context of the bathymetric distribution of species. The maxima in abundance and diversity occurred in February-March, for eggs, and May-June, for larvae. This 3-month time-lag between the stages is proposed to be related to the timing of egg spawning and larval recruitment to the pelagic environment. Mean egg abundances (82.4±29.8 eggs/10 m 2) were 10-fold higher than the larval abundances (7.1±1.8 larvae/10 m 2). Despite pronounced monthly variability, no statistically significant decrease in either egg or larvae abundance was observed during this 6-year study period. Compared with previous published studies, this study shows that the peak in ichthyoplankton diversity occurred two months earlier. In addition, the spawning period occurred over the whole year, even during autumn and winter. Using ordination techniques, the annual sequence appearance of taxa are described at the study site: Gadiforms, Ammodytidae and Pleuronectiforms were present during the winter whilst Sparidae, Blennidae, Labridae and Gobiidae, formed the summer group. Only three species, European anchovy Engraulis encrasicolus, European pilchard Sardina pilchardus and Atlantic horse mackerel Trachurus trachurus were recorded throughout the year.

Species profiles: Life history and environmental requirements of coastal fishes and invertebrates (South Florida): King mackerel and Spanish mackerel. [Scomberomorus cavalla; Scomberomorus maculatus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godcharles, M.F.; Murphy, M.D.

1986-06-01

This Species Profile on king and Spanish mackerel summarizes the taxonomy, morphology, distribution, life history, fishery descriptions, ecological role, and environmental requirements of these coastal pelagic fish to assist environmental impact assessment. King and Spanish mackerel support major commercial and sport fisheries in south Florida. In 1974 to 1983, Gulf of Mexico and Atlantic commercial landings of king mackerel declined from 10.4 to 4.3 million lb.; Spanish mackerel have fluctuated between 4.9 to 17.4 million lb. Both inhabit coastal waters, but Spanish mackerel are generally found closer to beaches and in outer estuarine waters. Both species feed principally on estuarine-dependentmore » species. They are highly migratory, exhibiting seasonal migrations to winter feeding grounds off south Florida and summer spawning/feeding grounds in the northern Gulf of Mexico and off the Atlantic coast of the Southeastern US. Spawning occurs from March/April through September/October between the middle and Outer Continental Shelf (35 to 183 mi) for king mackerel and the inner shelf (12 to 34 mi) for Spanish mackerel. King mackerel reach sexual maturity in their 3rd and 4th years and Spanish, between their 2nd and 3rd. Female king mackerel live longer and grow larger and faster than males. Spanish mackerel live to 8 years; females also grow faster than males. King and Spanish mackerel feed principally on schooling fishes. Larvae and juveniles of both species are prey to little tunny and dolphin; adults are prey for sharks and bottlenose dolphin. Temperature and salinity are important factors regulating mackerel distribution.« less

Deformation of the notochord by pressure from the swim bladder may cause malformation of the vertebral column in cultured Atlantic cod Gadus morhua larvae: a case study.

PubMed

Grotmol, Sindre; Kryvi, Harald; Totland, Geir K

2005-06-01

This study describes a malformation that frequently occurs in Atlantic cod Gadus morhua in intensive culture systems. The malformation is characterised by a slight upward tilt of the head and an indented dorsal body contour at the transition between the head and the trunk, and is first evident to the fish farmer when the cod reach the juvenile stage. These abnormalities are associated with malformations of the neurocranium, the cranial region of the vertebral column and the cranial part of the epaxial lateral muscles. The pathogenesis involves deformation of the notochord, which can be observed in larvae about 7 d post-hatch (dph) and onwards. The deformation consists of an increase in dorsal curvature of the notochord in the region above the swim bladder. In the same region, the notochord has an abnormal cross-sectional outline, characterised by a groove-shaped, longitudinal impression along the ventral surface of the sheath. In most cases, the swim bladder fills the impression, and in severely affected larvae it forms a hernia-like lesion in the notochord. The deformation of the notochord seems to be conveyed to the vertebral body anlagen (chordacentra), which in teleosts are formed by mineralisation within the notochordal sheath. The vertebral bodies adopt an abnormal wedge shape, with a ventral concavity, and the neural arches are most often S-shaped. A continuous range of degrees of the malformation can be observed. All these pathomorphological characteristics are compatible with the notion that the notochord has been subjected to an upward mechanical force, probably generated by a persistent increase in pressure between the swim bladder and the notochord during the period of development of the vertebral anlagen. Our results thus indicate that the critical time window with regard to development of the malformation is from 18 to 36 dph, when the initial formation of the vertebrae takes place. Chronic overinflation of the swim bladder or pathological dilatation of the digestive tract may cause the lesions, and aetiology may be related to factors that influence the function of these organs.

Episodic Eolian Sand Deposition in the Past 4000 Years in Cape COD National Seashore, Massachusetts, USA in Response to Possible Hurricane/storm and Anthropogenic Disturbances

NASA Astrophysics Data System (ADS)

Forman, Steven

2015-02-01

The eolian sand depositional record for a dune field within Cape Cod National Seashore, Massachusetts is posit as a sensitive indicator of environmental disturbances in the late Holocene from a combination of factors such as hurricane/storm and forest fire occurrence, and anthropogenic activity. Stratigraphic and sedimentologic observations, particularly the burial of spodosol-like soils, and associated 14C and OSL ages that are concordant indicate at least six eolian depositional events at ca. 3750, 2500, 1800, 960, 430 and <250 years ago. The two oldest events are documented at just one locality and thus, the pervasiveness of this eolian activity is unknown. However, the four younger events are identified in three or more sites and show evidence for dune migration and sand sheet accretion. The timing of eolian deposition, particularly the initiation age, corresponds to documented periods of increased storminess/hurricane activity in the North Atlantic Ocean at ca. 2.0 to 1.6, and 1.0 ka and also a wetter coastal climate, which suppressed the occurrence of forest fire. Thus, local droughts are not associated with periods of dune movement in this mesic environment. Latest eolian activity on outer Cape Cod commenced in the past 300 to 500 years and may reflect multiple factors including broad-scale landscape disturbance with European colonization, an increased incidence of forest fires and heightened storminess. Eolian systems of Cape Cod appear to be sensitive to landscape disturbance and prior to European settlement may reflect predominantly hurricane/storm disturbance, despite generally mesic conditions in past 4 ka.

Impact of beaver dams on abundance and distribution of anadromous salmonids in two lowland streams in Lithuania.

PubMed

Virbickas, Tomas; Stakėnas, Saulius; Steponėnas, Andrius

2015-01-01

European beaver dams impeded movements of anadromous salmonids as it was established by fishing survey, fish tagging and redd counts in two lowland streams in Lithuania. Significant differences in abundancies of other litophilic fish species and evenness of representation by species in the community were detected upstream and downstream of the beaver dams. Sea trout parr marked with RFID tags passed through several successive beaver dams in upstream direction, but no tagged fish were detected above the uppermost dam. Increase in abundances of salmonid parr in the stream between the beaver dams and decrease below the dams were recorded in November, at the time of spawning of Atlantic salmon and sea trout, but no significant changes were detected in the sections upstream of the dams. After construction of several additional beaver dams in the downstream sections of the studied streams, abundance of Atlantic salmon parr downstream of the dams decreased considerably in comparison with that estimated before construction.

Immune parameters in the intestine of wild and reared unvaccinated and vaccinated Atlantic salmon (Salmo salar L.).

PubMed

Løkka, Guro; Austbø, Lars; Falk, Knut; Bromage, Erin; Fjelldal, Per Gunnar; Hansen, Tom; Hordvik, Ivar; Koppang, Erling Olaf

2014-11-01

Forming a barrier to the outside world, the gut mucosa faces the challenge of absorbing nutrients and fluids while initiating immune reactions towards potential pathogens. As a continuation to our previous publication focusing on the regional intestinal morphology in wild caught post smolt and spawning Atlantic salmon, we here investigate selected immune parameters and compare wild, reared unvaccinated and vaccinated post smolts. We observed highest transcript levels for most immune-related genes in vaccinated post smolts followed by reared unvaccinated and finally wild post smolts, indicating that farming conditions like commercial feed and vaccination might contribute to a more alerted immune system in the gut. In all groups, higher levels of immune transcripts were observed in the second segment of mid-intestine and in the posterior segment. In the life stages and conditions investigated here, we found no indication of a previously suggested population of intestinal T cells expressing MHC class II nor RAG1 expression. Copyright © 2014 Elsevier Ltd. All rights reserved.

Multidimensionality of behavioural phenotypes in Atlantic cod, Gadus morhua.

PubMed

Meager, Justin J; Fernö, Anders; Skjæraasen, Jon Egil; Järvi, Torbjörn; Rodewald, Petra; Sverdrup, Gisle; Winberg, Svante; Mayer, Ian

2012-06-25

Much of the inter-individual variation observed in animal behaviour is now attributed to the existence of behavioural phenotypes or animal personalities. Such phenotypes may be fundamental to fisheries and aquaculture, yet there have been few detailed studies of this phenomenon in exploited marine animals. We investigated the behavioural and neuroendocrine responses of Atlantic cod (Gadus morhua L.), to situations reflecting critical ecological challenges: predator attacks and territorial challenges. Both hatchery-reared and wild fish were tested and behavioural profiles were compared with baseline conditions. We then used an objective, multivariate approach, rather than assigning individuals along one-dimensional behavioural axes, to examine whether distinct behavioural phenotypes were present. Our results indicate that two distinct behavioural phenotypes were evident in fish from each background. In hatchery-reared fish, phenotypes displayed divergent locomotor activity, sheltering, brain monoamine concentrations and responses to competitive challenges. In wild fish, phenotypes were distinguished primarily by locomotor activity, sheltering and responsiveness to predator stimuli. Hatcheries presumably represent a more stressful social environment, and social behaviour and neuroendocrine responses were important in discerning behavioural phenotypes in hatchery fish, whereas antipredator responses were important in discerning phenotypes in wild fish that have previously encountered predators. In both fish types, behavioural and physiological traits that classified individuals into phenotypes were not the same as those that were correlated across situations. These results highlight the multidimensionality of animal personalities, and that the processes that regulate one suite of behavioural traits may be very different to the processes that regulate other behaviours. Copyright © 2012 Elsevier Inc. All rights reserved.

A survey of dioxin-like contaminants in fish from recreational fishing.

PubMed

Heimstad, Eldbjørg Sofie; Grønstøl, Gaute; Hetland, Karl Torstein; Alarcon, Javier Martinez; Rylander, Charlotta; Mariussen, Espen

2015-08-01

The dioxin and dioxin-like compounds are regarded as one of the most toxic group of environmental contaminants. Food for the commercial market is regularly monitored for their dioxin levels and the concentration allowed in food is strictly regulated. Less is known about locally caught fish from recreational fishing, which is often brought home for consumption. This can be fish caught from nearby lakes or streams or fish with marine origin close to industrial areas or harbours that are not regularly monitored for their dioxin levels. In this study, we established collaboration with schools in 13 countries. We received 203 samples of 29 different fish species of which Atlantic cod was the most abundant followed by brown trout and pollock. In general, the majority of samples from the participating countries had low concentrations (between 0.1 and 0.2 pg/g chemical-activated luciferase gene expression toxic equivalency wet weight (CALUX TEQ w.w.)) of dioxins and dioxin-like PCBs. Only 18 samples had concentrations above 1 pg/g CALUX TEQ w.w., and only 2 dab samples had concentration above maximum levels set by the European Commission. The Atlantic cod samples showed a significant reduction in the concentrations of dioxins with increasing latitude indicating less contamination of dioxin and dioxin-like compounds in the north of Norway. The results indicate that a moderate consumption of self-caught fish at presumed non-contaminated sites does not represent a major risk for exposure to dioxins or dioxin-like compounds at concentrations associated with adverse health effects. Recreational fishermen should, however, obtain knowledge about local fish consumption advice.

Effects of temperature on specific dynamic action in Atlantic cod Gadus morhua.

PubMed

Tirsgaard, Bjørn; Svendsen, Jon Christian; Steffensen, John Fleng

2015-02-01

Growth requires that energy is directed towards ingestion, digestion, absorption and assimilation of a meal; energy expenditures are often expressed as the specific dynamic action (SDA). While SDA is an important part of fish energy budgets and strongly affected by water temperature, temperature effects are not known across a wide temperature range in Atlantic cod Gadus morhua. The objective of this study was to examine effects of temperature (2, 5, 10, 15 or 20 °C) on the energetic cost and time used for SDA in juvenile G. morhua by intermittent flow respirometry. At each temperature, G. morhua were fed a meal of herring (Clupea harengus) corresponding to 5 % of the body mass. Standard metabolic rates measured pre-feeding and post-feeding metabolic rates were measured to determine SDA. The study showed that SDA coefficients (%, SDA energy divided by meal energy) were significantly lower at 2 and 10 °C (5.4-6.3 %) compared to 5, 15 and 20 °C (10.4-12.4 %), while SDA duration increased significantly from 80 h at 10 °C to 130-160 h at 2, 15 and 20 °C and reached a maximum of 250 h at 5 °C. The significant decrease in SDA duration at 10 °C combined with a low SDA coefficient suggests that water temperatures close to 10 °C may represent the optimum temperatures for SDA in this population of G. morhua. Our results suggest that SDA is not a simple function of temperature, but may vary with temperature in a more complex fashion.

Earth Observations taken by Expedition 34 crewmember

NASA Image and Video Library

2013-02-14

ISS034-E-48455 (14 Feb. 2013) --- Looking out at Earth?s surface from the International Space Station (ISS), astronauts and cosmonauts frequently observe sunglint highlighting both ocean and inland water surfaces. The Atlantic Ocean, including Cape Cod Bay and Buzzards Bay, along the coastlines of Massachusetts and Rhode Island, has a burnished, mirror-like appearance in this image. This is due to sunlight reflected off the water surface back towards the station crew member who took the photo. The peak reflection point is towards the right side of the image, lending the waters of Long Island Sound and the upper Massachusetts coastline an even brighter appearance. Sunglint also illuminates the surface waters of Chesapeake Bay, located over 400 kilometers (250 miles) to the southwest of the tip of Long Island. This suggests that the Sun was low on the horizon due to the observed extent of the sunglint effect. The time of image acquisition, approximately 4:26 p.m. Eastern Standard Time, was about one hour before local sunset. There is little in this image to indicate that the region was still recovering from a major winter storm that dropped almost one meter (three feet) of snow over much of the northeastern USA less than a week earlier. The high viewing angle from the space station also allows Earth?s curvature, or limb, to be seen; blue atmospheric layers gradually fade into the darkness of space across the top part of the image. Low clouds near Cape Cod, Long Island, and further down the Atlantic coastline cast shadows over the water surfaces, reducing the sunglint in some areas.

Dangerous dining: surface foraging of North Atlantic right whales increases risk of vessel collisions.

PubMed

Parks, Susan E; Warren, Joseph D; Stamieszkin, Karen; Mayo, Charles A; Wiley, David

2012-02-23

North Atlantic right whales are critically endangered and, despite international protection from whaling, significant numbers die from collisions with ships. Large groups of right whales migrate to the coastal waters of New England during the late winter and early spring to feed in an area with large numbers of vessels. North Atlantic right whales have the largest per capita record of vessel strikes of any large whale population in the world. Right whale feeding behaviour in Cape Cod Bay (CCB) probably contributes to risk of collisions with ships. In this study, feeding right whales tagged with archival suction cup tags spent the majority of their time just below the water's surface where they cannot be seen but are shallow enough to be vulnerable to ship strike. Habitat surveys show that large patches of right whale prey are common in the upper 5 m of the water column in CCB during spring. These results indicate that the typical spring-time foraging ecology of right whales may contribute to their high level of mortality from vessel collisions. The results of this study suggest that remote acoustic detection of prey aggregations may be a useful supplement to the management and conservation of right whales.

Parasites as biological tags in marine fisheries research: European Atlantic waters.

PubMed

Mackenzie, K; Hemmingsen, W

2015-01-01

Studies of the use of parasites as biological tags for stock identification and to follow migrations of marine fish, mammals and invertebrates in European Atlantic waters are critically reviewed and evaluated. The region covered includes the North, Baltic, Barents and White Seas plus Icelandic waters, but excludes the Mediterranean and Black Seas. Each fish species or ecological group of species is treated separately. More parasite tag studies have been carried out on Atlantic herring Clupea harengus than on any other species, while cod Gadus morhua have also been the subject of many studies. Other species that have been the subjects of more than one study are: blue whiting Micromesistius poutassou, whiting Merlangius merlangus, haddock Melanogrammus aeglefinus, Norway pout Trisopterus esmarkii, horse mackerel Trachurus trachurus and mackerel Scomber scombrus. Other species are dealt with under the general headings redfishes, flatfish, tunas, anadromous fish, elasmobranchs, marine mammals and invertebrates. A final section highlights how parasites can be, and have been, misused as biological tags, and how this can be avoided. It also reviews recent developments in methodology and parasite genetics, considers the potential effects of climate change on the distributions of both hosts and parasites, and suggests host-parasite systems that should reward further research.

North Atlantic summers have warmed more than winters since 1353, and the response of marine zooplankton.

PubMed

Kamenos, Nicholas A

2010-12-28

Modeling and measurements show that Atlantic marine temperatures are rising; however, the low temporal resolution of models and restricted spatial resolution of measurements (i) mask regional details critical for determining the rate and extent of climate variability, and (ii) prevent robust determination of climatic impacts on marine ecosystems. To address both issues for the North East Atlantic, a fortnightly resolution marine climate record from 1353-2006 was constructed for shallow inshore waters and compared to changes in marine zooplankton abundance. For the first time summer marine temperatures are shown to have increased nearly twice as much as winter temperatures since 1353. Additional climatic instability began in 1700 characterized by ∼5-65 year climate oscillations that appear to be a recent phenomenon. Enhanced summer-specific warming reduced the abundance of the copepod Calanus finmarchicus, a key food item of cod, and led to significantly lower projected abundances by 2040 than at present. The faster increase of summer marine temperatures has implications for climate projections and affects abundance, and thus biomass, near the base of the marine food web with potentially significant feedback effects for marine food security.

Rising seas and sinking coastal marshes: Implications to Atlantic waterbirds

USGS Publications Warehouse

Erwin, R.M.; Prosser, D.J.; Sanders, G.

2000-01-01

Along the mid-Atlantic U.S. coast, relative sea level rise (RSLR) is higher than the global average of 1.5-2.0 mm/yr, ranging from about 2.5 in parts of Virginia and Delaware to about 4.0 in New Jersey (Atlantic City and Sandy Hook) and near the mouth of Chesapeake Bay, Virginia. Very few data exist on marsh elevation changes, but information from some areas in Virginia, New Jersey and New York suggest that marsh islands are not 'keeping pace' with this RSLR. We began a study in 1999 that addresses changes in sea level and marsh elevation at sites from Cape Cod to s. Virginia known to be important areas for migratory waterbirds, including waterfowl, shorebirds, wading birds, and seabirds. Marsh monitoring sites have been established and data on microhabitat use by birds during all 4 seasons is being collected at these sites. Species expected to be most vulnerable to RSLR in these marshes are breeding species such as Laughing Gulls, Common, Gull-billed and Forster's terns, Clapper Rails, and American Black Ducks. Most of these species are of special concern at state, regional, or national levels. We show how important this region to these species from a flyway perspective, with> 70% of all Atlantic coast Laughing Gulls and Forster's Terns nesting from New Jersey to Virginia.

Anadromous sea lampreys recolonize a Maine coastal river tributary after dam removal

USGS Publications Warehouse

Hogg, Robert; Coghlan, Stephen M.; Zydlewski, Joseph D.

2013-01-01

Sedgeunkedunk Stream, a third-order tributary to the Penobscot River, Maine, historically supported several anadromous fishes, including the Atlantic Salmon Salmo salar, AlewifeAlosa pseudoharengus, and Sea Lamprey Petromyzon marinus. However, two small dams constructed in the 1800s reduced or eliminated spawning runs entirely. In 2009, efforts to restore marine–freshwater connectivity in the system culminated with removal of the lowermost dam, thus providing access to an additional 4.6 km of lotic habitat. Because Sea Lampreys utilized accessible habitat prior to dam removal, they were chosen as a focal species with which to quantify recolonization. During spawning runs of 2008–2011 (before and after dam removal), individuals were marked with PIT tags and their activity was tracked with daily recapture surveys. Open-population mark–recapture models indicated a fourfold increase in the annual abundance of spawning-phase Sea Lampreys, with estimates rising from 59±4 () before dam removal (2008) to 223±18 and 242±16 after dam removal (2010 and 2011, respectively). Accompanying the marked increase in annual abundance was a greater than fourfold increase in nesting sites: the number of nests increased from 31 in 2008 to 128 and 131 in 2010 and 2011, respectively. During the initial recolonization event (i.e., in 2010), Sea Lampreys took 6 d to move past the former dam site and 9 d to expand into the furthest upstream reaches. Conversely, during the 2011 spawning run, Sea Lampreys took only 3 d to penetrate into the upstream reaches, thus suggesting a potential positive feedback in which larval recruitment into the system may have attracted adult spawners via conspecific pheromone cues. Although more research is needed to verify the migratory pheromone hypothesis, our study clearly demonstrates that small-stream dam removal in coastal river systems has the potential to enhance recovery of declining anadromous fish populations.

Population ecology of turbot and brill: What can we learn from two rare flatfish species?

NASA Astrophysics Data System (ADS)

van der Hammen, Tessa; Poos, Jan Jaap; van Overzee, Harriët M. J.; Heessen, Henk J. L.; Magnusson, Arni; Rijnsdorp, Adriaan D.

2013-11-01

Turbot and brill are widely distributed in the Northeast Atlantic but occur at low abundance. They are ecologically very similar and closely related. The low abundance and the similarities make them particularly interesting to study the population dynamics because it raises the questions how the populations can sustain themselves at low abundances and how turbot and brill avoid strong interspecific competition. Knowledge of both species is hampered by lack of analysed data. The main objective of this study is therefore to increase the knowledge of turbot and brill and in particular to compare the two species in order to address the above questions. Based on biological samples collected in the North Sea, we calculated seasonal von Bertalanffy growth parameters, maturity ogives, monthly gonado-somatic indices (GSI) and condition factors (Fulton's K) and indices of inter- and intraspecific mean crowding and compared the results for turbot and brill. The main differences between the two species were found in their spawning period, with brill having a more protracted spawning period. Brill also showed an earlier peak in their GSI values, suggesting an earlier start of their spawning period. The mean crowding showed that interspecific competition was lower than intraspecific competition. The exploitation pattern was also studied. Turbot and brill are exploited as a bycatch species in the mixed demersal fishery. We found that productivity is highest in areas where the maximum temperature is close to the optimal temperature for growth (16-18 °C) and landings decrease where salinity falls below ~ 5 psu (turbot) and ~ 15 psu (brill). Recent fishing mortality rates of North Sea turbot are around 0.5-0.7, but there is no indication that recruitment is impaired at low levels of spawning stock biomass. We conclude that although both species have similar ecological characteristics, differences may reduce inter-specific competition.

PIT-tagged particle study of bed mobility in a Maine salmon river impacted by logging activities

NASA Astrophysics Data System (ADS)

Thompson, D. M.; Fixler, S. A.; Roberts, K. E.; McKenna, M.; Marshall, A. E.; Koenig, S.

2017-12-01

Presenting an interim report on a study on the Narraguagus River in Maine, which utilizes laser total stations cross-sectional surveys and tracking of passive integrated transponder (PIT) tags embedded in glass spheres to document changes in channel-bed characteristics associated with large wood (LW) additions and natural spawning activities. In 2016, work was initiated to monitor changes in bed elevation and sediment mobility with the addition of LW to the Narraguagus River as part of a restoration effort. Ten cross-sections, spaced 5-m apart, were established and surveyed with a laser total station in each of three different study reaches. The study sites include a control reach, a section with anticipated spawning activities and a site with ongoing LW placement. A grid of 200 glass spheres embedded with PIT tags, with twenty alternating 25-mm and 40-mm size particles equally spaced along each of the ten transects, were placed to serve as point sensors to detect sediment mobilization within each reach. In 2017, the site was revisited to determine if differences in PIT-tagged tracer particle mobilization reflect locations were LW was added and places where Atlantic salmon (Salmo salar) and sea lamprey (Petromyzon marinus) construct spawning redds. The positions of PIT-tagged tracer particles was recorded, but particles were not disturbed or uncovered to permit study of potential reworking of buried tracer particles the following year. Full tracer particle recovery will be determined in 2018 to determine if depths of tracer burial and changes in bed elevation vary among places near redds, LW and main channel locations. The data will be used to determine if salmon redds are preferentially located in either places with greater evidence of sediment reworking or alternatively in stable areas? The study will help determine the degree of bed disruption associated with spawning activities and whether LW placement encourages similar sediment mobilization processes.

The effect of exposure to farmed salmon on piscine orthoreovirus infection and fitness in wild Pacific salmon in British Columbia, Canada

PubMed Central

2017-01-01

The disease Heart and Skeletal Muscle Inflammation (HSMI) is causing substantial economic losses to the Norwegian salmon farming industry where the causative agent, piscine orthoreovirus (PRV), is reportedly spreading from farmed to wild Atlantic salmon (Salmo salar) with as yet undetermined impacts. To assess if PRV infection is epidemiologically linked between wild and farmed salmon in the eastern Pacific, wild Pacific salmon (Oncorhynchus sp.) from regions designated as high or low exposure to salmon farms and farmed Atlantic salmon reared in British Columbia (BC) were tested for PRV. The proportion of PRV infection in wild fish was related to exposure to salmon farms (p = 0.0097). PRV was detected in: 95% of farmed Atlantic salmon, 37–45% of wild salmon from regions highly exposed to salmon farms and 5% of wild salmon from the regions furthest from salmon farms. The proportion of PRV infection was also significantly lower (p = 0.0008) where wild salmon had been challenged by an arduous return migration into high-elevation spawning habitat. Inter-annual PRV infection declined in both wild and farmed salmon from 2012–2013 (p ≤ 0.002). These results suggest that PRV transfer is occurring from farmed Atlantic salmon to wild Pacific salmon, that infection in farmed salmon may be influencing infection rates in wild salmon, and that this may pose a risk of reduced fitness in wild salmon impacting their survival and reproduction. PMID:29236731

The effect of exposure to farmed salmon on piscine orthoreovirus infection and fitness in wild Pacific salmon in British Columbia, Canada.

PubMed

Morton, Alexandra; Routledge, Richard; Hrushowy, Stacey; Kibenge, Molly; Kibenge, Frederick

2017-01-01

The disease Heart and Skeletal Muscle Inflammation (HSMI) is causing substantial economic losses to the Norwegian salmon farming industry where the causative agent, piscine orthoreovirus (PRV), is reportedly spreading from farmed to wild Atlantic salmon (Salmo salar) with as yet undetermined impacts. To assess if PRV infection is epidemiologically linked between wild and farmed salmon in the eastern Pacific, wild Pacific salmon (Oncorhynchus sp.) from regions designated as high or low exposure to salmon farms and farmed Atlantic salmon reared in British Columbia (BC) were tested for PRV. The proportion of PRV infection in wild fish was related to exposure to salmon farms (p = 0.0097). PRV was detected in: 95% of farmed Atlantic salmon, 37-45% of wild salmon from regions highly exposed to salmon farms and 5% of wild salmon from the regions furthest from salmon farms. The proportion of PRV infection was also significantly lower (p = 0.0008) where wild salmon had been challenged by an arduous return migration into high-elevation spawning habitat. Inter-annual PRV infection declined in both wild and farmed salmon from 2012-2013 (p ≤ 0.002). These results suggest that PRV transfer is occurring from farmed Atlantic salmon to wild Pacific salmon, that infection in farmed salmon may be influencing infection rates in wild salmon, and that this may pose a risk of reduced fitness in wild salmon impacting their survival and reproduction.

Fish community response to dam removal in a Maine coastal river tributary

USGS Publications Warehouse

Zydlewski, Joseph D.; Hogg, Robert S.; Coghlan, Stephen M.; Gardner, Cory

2016-01-01

Sedgeunkedunk Stream, a third-order tributary to the Penobscot River in Maine, historically has supported several anadromous fishes including Atlantic Salmon Salmo salar, Alewife Alosa pseudoharengus, and Sea Lamprey Petromyzon marinus. Two small dams constructed in the 1800s reduced or eliminated spawning runs entirely. In 2009, efforts to restore marine–freshwater connectivity in the system culminated in removal of the lowermost dam (Mill Dam) providing access to 4.7 km of lotic habitat and unimpeded passage into the lentic habitat of Fields Pond. In anticipation of these barrier removals, we initiated a modified before-after-control-impact study, and monitored stream fish assemblages in fixed treatment and reference sites. Electrofishing surveys were conducted twice yearly since 2007. Results indicated that density, biomass, and diversity of the fish assemblage increased at all treatment sites upstream of the 2009 dam removal. No distinct changes in these metrics occurred at reference sites. We documented recolonization and successful reproduction of Atlantic Salmon, Alewife, and Sea Lamprey in previously inaccessible upstream reaches. These results clearly demonstrate that dam removal has enhanced the fish assemblage by providing an undisrupted stream gradient linking a small headwater lake and tributary with a large coastal river, its estuary, and the Atlantic Ocean.

Effects of thiamine on reproduction of Atlantic salmon and a new hypothesis for their extirpation in Lake Ontario

USGS Publications Warehouse

Ketola, H. George; Bowser, Paul R.; Wooster, Gregory A.; Wedge, Leslie R.; Hurst, Steven S.

2000-01-01

Previous researchers demonstrated that a mortality in fry (called Cayuga syndrome) of Atlantic salmon Salmo salar from Cayuga Lake (New York) was associated with low levels of thiamine. They reduced the mortality of fry by bathing or injecting fry with thiamine. We injected four to six gravid female Atlantic salmon with either physiological saline (PS) or PS plus thiamine (7 mg/kg weight) 14–23 d before eggs were stripped, fertilized, and incubated in individual lots. Chemical analyses showed that eggs from control and treated salmon contained 1.1 and 1.6 nmol thiamine/g, respectively. Thiamine injections had no significant effect on the percentage of eggs that hatched. Between 700 and 800 Celius degree-days postfertilization, control fry (saline) showed signs of Cayuga syndrome and a 45% incidence of mortality; in contrast, mortality was only 1.9% for fry that received thiamine. By 1,078 degree-days postfertilization, mean mortality of control fry was 98.6%, whereas that for thiamine-injected salmon was 2.1%. This study showed that thiamine injections of prespawning female salmon from Cayuga Lake increased thiamine content of their eggs and prevented the Cayuga syndrome and subsequent mortality of fry. Historically, overfishing, pollution, and building of dams and barriers to spawning migration were suggested as possible causes of the decline of the Atlantic salmon in Lake Ontario and Cayuga Lake. Based on our findings and other reports, we suggest another possible contributing cause of the extirpation of landlocked Atlantic salmon in Lake Ontario and some other inland waters of New York: The entrance of alewives Alosa pseudoharengus containing thiaminase, which induced thiamine deficiency in eggs and increased mortality in fry of the predatory salmon.

Vast assembly of vocal marine mammals from diverse species on fish spawning ground.

PubMed

Wang, Delin; Garcia, Heriberto; Huang, Wei; Tran, Duong D; Jain, Ankita D; Yi, Dong Hoon; Gong, Zheng; Jech, J Michael; Godø, Olav Rune; Makris, Nicholas C; Ratilal, Purnima

2016-03-17

Observing marine mammal (MM) populations continuously in time and space over the immense ocean areas they inhabit is challenging but essential for gathering an unambiguous record of their distribution, as well as understanding their behaviour and interaction with prey species. Here we use passive ocean acoustic waveguide remote sensing (POAWRS) in an important North Atlantic feeding ground to instantaneously detect, localize and classify MM vocalizations from diverse species over an approximately 100,000 km(2) region. More than eight species of vocal MMs are found to spatially converge on fish spawning areas containing massive densely populated herring shoals at night-time and diffuse herring distributions during daytime. We find the vocal MMs divide the enormous fish prey field into species-specific foraging areas with varying degrees of spatial overlap, maintained for at least two weeks of the herring spawning period. The recorded vocalization rates are diel (24 h)-dependent for all MM species, with some significantly more vocal at night and others more vocal during the day. The four key baleen whale species of the region: fin, humpback, blue and minke have vocalization rate trends that are highly correlated to trends in fish shoaling density and to each other over the diel cycle. These results reveal the temporospatial dynamics of combined multi-species MM foraging activities in the vicinity of an extensive fish prey field that forms a massive ecological hotspot, and would be unattainable with conventional methodologies. Understanding MM behaviour and distributions is essential for management of marine ecosystems and for accessing anthropogenic impacts on these protected marine species.

Gender specific reproductive strategies of an arctic key species (Boreogadus saida) and implications of climate change.

PubMed

Nahrgang, Jasmine; Varpe, Oystein; Korshunova, Ekaterina; Murzina, Svetlana; Hallanger, Ingeborg G; Vieweg, Ireen; Berge, Jørgen

2014-01-01

The Arctic climate is changing at an unprecedented rate. What consequences this may have on the Arctic marine ecosystem depends to a large degree on how its species will respond both directly to elevated temperatures and more indirectly through ecological interactions. But despite an alarming recent warming of the Arctic with accompanying sea ice loss, reports evaluating ecological impacts of climate change in the Arctic remain sparse. Here, based upon a large-scale field study, we present basic new knowledge regarding the life history traits for one of the most important species in the entire Arctic, the polar cod (Boreogadus saida). Furthermore, by comparing regions of contrasting climatic influence (domains), we present evidence as to how its growth and reproductive success is impaired in the warmer of the two domains. As the future Arctic is predicted to resemble today's Atlantic domains, we forecast changes in growth and life history characteristics of polar cod that will lead to alteration of its role as an Arctic keystone species. This will in turn affect community dynamics and energy transfer in the entire Arctic food chain.

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (North Atlantic)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buckley, J.

1989-08-01

Species profiles are literature summaries of the taxonomy, life history, and environmental requirements of coastal fishes and aquatic invertebrates. They are designed to assist with environmental impact assessments. The rainbow smelt is an abundant forage fish for commercially and recreationally valuable fishes such as striped bass and bluefish on the East Coast and several species of salmon and trout in the Great Lakes. The rainbow smelt also supports an important sportfishery throughout most of its range. In 1976, the total smelt harvest in the coastal waters of New England was 105,000 lb. Coastal rainbow smelt are anadromous, spawning in freshwatermore » and maturing in saline water. Spawning peaks in spring. Salinities above 12 ppt were fatal to eggs. Reported fecundities are 7,000 to 44,000 eggs per female. Smelt are always found in shallow water (<6 m deep) and within 2 km of the shore. Larval and juvenile smelt along the coast feed on planktonic crustaceans. Larger juveniles and adults feed on euphausiids, amphipods, on planktonic crustaceans. Larger juveniles and adults feed on euphausiids, amphipods, polychaetes, and fish. Smelt move locally to search for optimum water temperatures. 46 refs., 2 figs., 1 tab.« less

Migration and reproductive biology of Mugil liza (Teleostei: Mugilidae) in south Brazil.

PubMed

Lemos, V M; Varela, A S; Schwingel, P R; Muelbert, J H; Vieira, J P

2014-09-01

The mullet Mugil liza occurs along the Atlantic coast of South America from Venezuela to Argentina, but 95% of the commercial catch is collected from south Brazil between São Paulo and Argentina. Mugil liza is a single spawner with oocyte development occurring synchronously in two groups. Spawning happens in marine areas and occurs after migration. The reproductive migration occurs from Argentina (38° S) to the southern Brazilian states (24-26° S) from April to July, with peak spawning in June between northern Santa Catarina and Paraná. The presence of hyaline oocytes was associated with high salinity and sea surface temperatures of 19-21° C, and followed the seasonal northward displacement of these oceanographic conditions. The average size at first maturity (Lm ) for both sexes was 408·3 mm total length, LT . Males (Lm  = 400·1) matured earlier than females (Lm  = 421·9 mm). Fecundity ranged from 818,992 to 2,869,767 oocytes (mean = 1,624,551) in fish that were between 426 and 660 mm LT . © 2014 The Fisheries Society of the British Isles.

The size, mass, and composition of plastic debris in the western North Atlantic Ocean.

PubMed

Morét-Ferguson, Skye; Law, Kara Lavender; Proskurowski, Giora; Murphy, Ellen K; Peacock, Emily E; Reddy, Christopher M

2010-10-01

This study reports the first inventory of physical properties of individual plastic debris in the North Atlantic. We analyzed 748 samples for size, mass, and material composition collected from surface net tows on 11 expeditions from Cape Cod, Massachusetts to the Caribbean Sea between 1991 and 2007. Particles were mostly fragments less than 10mm in size with nearly all lighter than 0.05 g. Material densities ranged from 0.808 to 1.24 g ml(-1), with about half between 0.97 and 1.04 g ml(-1), a range not typically found in virgin plastics. Elemental analysis suggests that samples in this density range are consistent with polypropylene and polyethylene whose densities have increased, likely due to biofouling. Pelagic densities varied considerably from that of beach plastic debris, suggesting that plastic particles are modified during their residence at sea. These analyses provide clues in understanding particle fate and potential debris sources, and address ecological implications of pelagic plastic debris. Copyright © 2010 Elsevier Ltd. All rights reserved.

Monitoring Ground-Water Quality in Coastal Ecosystems

USGS Publications Warehouse

Colman, John A.; Masterson, John P.

2007-01-01

INTRODUCTION The Cape Cod National Seashore (CACO) extends along more than 70 km of Atlantic Ocean open-beach coastline and includes three large saltwater bays - Wellfleet Harbor, Nauset Marsh, and Pleasant Bay (fig. 1). CACO encompasses about 18,000 ha of uplands, lakes, wetlands, and tidal lands (Godfrey and others, 1999) including most habitats typical of the sandy coast in National seashores and parks extending southward from Massachusetts to Florida. In 1995, CACO was selected by the National Park Service (NPS) as a prototype park typifying the Atlantic and Gulf Coast biogeographic region for long-term coastal ecosystem monitoring. The U.S. Geological Survey (USGS) is currently (2007) assisting the NPS in the development of protocols for a Long-Term Coastal Ecosystem Monitoring Program at the CACO in Massachusetts. The overall purpose of the monitoring program is to characterize both natural and human-induced change in the biological resources of the CACO, over a time scale of decades, in the context of a changing global ecosystem.

Measurement-based estimates of direct radiative effects of absorbing aerosols above clouds

NASA Astrophysics Data System (ADS)

Feng, Nan; Christopher, Sundar A.

2015-07-01

The elevated layers of absorbing smoke aerosols from western African (e.g., Gabon and Congo) biomass burning activities have been frequently observed above low-level stratocumulus clouds off the African coast, which presents an excellent natural laboratory for studying the effects of aerosols above clouds (AAC) on regional energy balance in tropical and subtropical environments. Using spatially and temporally collocated Moderate Resolution Imaging Spectroradiometer, Ozone Monitoring Instrument (OMI), and Clouds and the Earth's Radiant Energy System data sets, the top-of-atmosphere shortwave aerosol direct shortwave radiative effects (ARE) of absorbing aerosols above low-level water clouds in the southeast Atlantic Ocean was examined in this study. The regional averaged instantaneous ARE has been estimated to be 36.7 ± 20.5 Wm-2 (regional mean ± standard deviation) along with a mean positive OMI Aerosol Index at 1.3 in August 2006 based on multisensors measurements. The highest magnitude of instantaneous ARE can even reach 138.2 Wm-2. We assess that the 660 nm cloud optical depth (COD) values of 8-12 is the critical value above (below) which aerosol absorption (scattering) effect dominates and further produces positive (negative) ARE values. The results further show that ARE values are more sensitive to aerosols above lower COD values than cases for higher COD values. This is among the first studies to provide quantitative estimates of shortwave ARE due to AAC events from an observational perspective.

Long-term observation of aerosol-cloud relationships in the Mid-Atlantic of the United States

NASA Astrophysics Data System (ADS)

Li, S.; Joseph, E.; Min, Q.; Yin, B.

2014-07-01

Long-term ground-based observations (2006 to 2010) of aerosol and cloud properties derived from passive radiometric sensors deployed at an atmospheric measurement field station in the Baltimore-Washington corridor operated by Howard University were used to examine aerosol indirect effect on cloud optical depth (COD), liquid water path (LWP), cloud droplets effective radius (Re) and cloud droplets number concentration (Nd). A higher frequency of clouds with large COD (> 20) and small Re (< 7 m) was found during summer of 2006 and 2007 along with higher frequency of abundant aerosol loading. The five-year data are screened for summer months only and are separated into clean and polluted cases based on aerosol particulate matter with aerodynamic diameter ≤ 2.5 m (PM2.5) value. Evidence of aerosol indirect effect is found where for polluted cases the mean and median values of COD and Nd distributions were elevated while the mean and median values of Re were decreased. Further reinforcing this conclusion is the result that the mean and median values of LWP distributions did not show prominent difference between clean and polluted cases, this implies that differences between the two cases of influential factors on cloud properties were relatively controlled. Moreover aerosol indirect effects were found insignificant when LWP was small but significant when LWP was large through the analysis of sensitivity of Nd to LWP under different aerosol loading and the measurements of aerosol size distribution.

Inferring genetic connectivity in real populations, exemplified by coastal and oceanic Atlantic cod.

PubMed

Spies, Ingrid; Hauser, Lorenz; Jorde, Per Erik; Knutsen, Halvor; Punt, André E; Rogers, Lauren A; Stenseth, Nils Chr

2018-05-08

Genetic data are commonly used to estimate connectivity between putative populations, but translating them to demographic dispersal rates is complicated. Theoretical equations that infer a migration rate based on the genetic estimator F ST , such as Wright's equation, F ST ≈ 1/(4 N e m + 1), make assumptions that do not apply to most real populations. How complexities inherent to real populations affect migration was exemplified by Atlantic cod in the North Sea and Skagerrak and was examined within an age-structured model that incorporated genetic markers. Migration was determined under various scenarios by varying the number of simulated migrants until the mean simulated level of genetic differentiation matched a fixed level of genetic differentiation equal to empirical estimates. Parameters that decreased the N e / N t ratio (where N e is the effective and N t is the total population size), such as high fishing mortality and high fishing gear selectivity, increased the number of migrants required to achieve empirical levels of genetic differentiation. Higher maturity-at-age and lower selectivity increased N e / N t and decreased migration when genetic differentiation was fixed. Changes in natural mortality, fishing gear selectivity, and maturity-at-age within expected limits had a moderate effect on migration when genetic differentiation was held constant. Changes in population size had the greatest effect on the number of migrants to achieve fixed levels of F ST , particularly when genetic differentiation was low, F ST ≈ 10 -3 Highly variable migration patterns, compared with constant migration, resulted in higher variance in genetic differentiation and higher extreme values. Results are compared with and provide insight into the use of theoretical equations to estimate migration among real populations. Copyright © 2018 the Author(s). Published by PNAS.

Temperature Modulates the Effects of Ocean Acidification on Intestinal Ion Transport in Atlantic Cod, Gadus morhua

PubMed Central

Hu, Marian Y.; Michael, Katharina; Kreiss, Cornelia M.; Stumpp, Meike; Dupont, Sam; Tseng, Yung-Che; Lucassen, Magnus

2016-01-01

CO2-driven seawater acidification has been demonstrated to enhance intestinal bicarbonate secretion rates in teleosts, leading to an increased release of CaCO3 under simulated ocean acidification scenarios. In this study, we investigated if increasing CO2 levels stimulate the intestinal acid–base regulatory machinery of Atlantic cod (Gadus morhua) and whether temperatures at the upper limit of thermal tolerance stimulate or counteract ion regulatory capacities. Juvenile G. morhua were acclimated for 4 weeks to three CO2 levels (550, 1200, and 2200 μatm) covering present and near-future natural variability, at optimum (10°C) and summer maximum temperature (18°C), respectively. Immunohistochemical analyses revealed the subcellular localization of ion transporters, including Na+/K+-ATPase (NKA), Na+/H+-exchanger 3 (NHE3), Na+/HCO3− cotransporter (NBC1), pendrin-like Cl−/HCO3− exchanger (SLC26a6), V-type H+-ATPase subunit a (VHA), and Cl− channel 3 (CLC3) in epithelial cells of the anterior intestine. At 10°C, proteins and mRNA were generally up-regulated for most transporters in the intestinal epithelium after acclimation to higher CO2 levels. This supports recent findings demonstrating increased intestinal HCO3− secretion rates in response to CO2 induced seawater acidification. At 18°C, mRNA expression and protein concentrations of most ion transporters remained unchanged or were even decreased, suggesting thermal compensation. This response may be energetically favorable to retain blood HCO3− levels to stabilize pHe, but may negatively affect intestinal salt and water resorption of marine teleosts in future oceans. PMID:27313538

Temperature Modulates the Effects of Ocean Acidification on Intestinal Ion Transport in Atlantic Cod, Gadus morhua.

PubMed

Hu, Marian Y; Michael, Katharina; Kreiss, Cornelia M; Stumpp, Meike; Dupont, Sam; Tseng, Yung-Che; Lucassen, Magnus

2016-01-01

CO2-driven seawater acidification has been demonstrated to enhance intestinal bicarbonate secretion rates in teleosts, leading to an increased release of CaCO3 under simulated ocean acidification scenarios. In this study, we investigated if increasing CO2 levels stimulate the intestinal acid-base regulatory machinery of Atlantic cod (Gadus morhua) and whether temperatures at the upper limit of thermal tolerance stimulate or counteract ion regulatory capacities. Juvenile G. morhua were acclimated for 4 weeks to three CO2 levels (550, 1200, and 2200 μatm) covering present and near-future natural variability, at optimum (10°C) and summer maximum temperature (18°C), respectively. Immunohistochemical analyses revealed the subcellular localization of ion transporters, including Na(+)/K(+)-ATPase (NKA), Na(+)/H(+)-exchanger 3 (NHE3), Na(+)/[Formula: see text] cotransporter (NBC1), pendrin-like Cl(-)/[Formula: see text] exchanger (SLC26a6), V-type H(+)-ATPase subunit a (VHA), and Cl(-) channel 3 (CLC3) in epithelial cells of the anterior intestine. At 10°C, proteins and mRNA were generally up-regulated for most transporters in the intestinal epithelium after acclimation to higher CO2 levels. This supports recent findings demonstrating increased intestinal [Formula: see text] secretion rates in response to CO2 induced seawater acidification. At 18°C, mRNA expression and protein concentrations of most ion transporters remained unchanged or were even decreased, suggesting thermal compensation. This response may be energetically favorable to retain blood [Formula: see text] levels to stabilize pHe, but may negatively affect intestinal salt and water resorption of marine teleosts in future oceans.

It is the economy, stupid! Projecting the fate of fish populations using ecological-economic modeling.

PubMed

Quaas, Martin F; Reusch, Thorsten B H; Schmidt, Jörn O; Tahvonen, Olli; Voss, Rudi

2016-01-01

Four marine fish species are among the most important on the world market: cod, salmon, tuna, and sea bass. While the supply of North American and European markets for two of these species - Atlantic salmon and European sea bass - mainly comes from fish farming, Atlantic cod and tunas are mainly caught from wild stocks. We address the question what will be the status of these wild stocks in the midterm future, in the year 2048, to be specific. Whereas the effects of climate change and ecological driving forces on fish stocks have already gained much attention, our prime interest is in studying the effects of changing economic drivers, as well as the impact of variable management effectiveness. Using a process-based ecological-economic multispecies optimization model, we assess the future stock status under different scenarios of change. We simulate (i) technological progress in fishing, (ii) increasing demand for fish, and (iii) increasing supply of farmed fish, as well as the interplay of these driving forces under different scenarios of (limited) fishery management effectiveness. We find that economic change has a substantial effect on fish populations. Increasing aquaculture production can dampen the fishing pressure on wild stocks, but this effect is likely to be overwhelmed by increasing demand and technological progress, both increasing fishing pressure. The only solution to avoid collapse of the majority of stocks is institutional change to improve management effectiveness significantly above the current state. We conclude that full recognition of economic drivers of change will be needed to successfully develop an integrated ecosystem management and to sustain the wild fish stocks until 2048 and beyond. © 2015 John Wiley & Sons Ltd.

Origin of Atlantic Sturgeon collected off the Delaware coast during spring months

USGS Publications Warehouse

Wirgin, Isaac; Breece, Matthew W.; Fox, Dewayne A.; Maceda, Lorraine; Wark, Kevin W.; King, Timothy L.

2015-01-01

Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus was federally listed under the U.S. Endangered Species Act as five distinct population segments (DPS). Currently, at least 18 estuaries coastwide host spawning populations and the viability of these vary, requiring differing levels of protection. Subadults emigrate from their natal estuaries to marine waters where they are vulnerable to bycatch; one of the major threats to the rebuilding of populations. As a result, identifying the population origin of Atlantic Sturgeon in coastal waters is critical to development of management plans intended to minimize interactions of the most imperiled populations with damaging fisheries. We used mitochondrial DNA control region sequencing and microsatellite DNA analyses to determine the origin of 261 Atlantic Sturgeon collected off the Delaware coast during the spring months. Using individual-based assignment (IBA) testing and mixed stock analysis, we found that specimens originated from all nine of our reference populations and the five DPSs used in the listing determination. Using IBA, we found that the Hudson River population was the largest contributor (38.3%) to our coastal collection. The James (19.9%) and Delaware (13.8%) river populations, at one time thought to be extirpated or nearly so, were the next largest contributors. The three populations combined in the South Atlantic DPS contributed 21% of specimens; the Altamaha River, the largest population in the South Atlantic DPS, only contributed a single specimen to the collection. While the origin of specimens collected on the Delaware coast was most likely within rivers of the New York Bight DPS (52.1%), specimens that originated elsewhere were also well represented. Genetic analyses provide a robust tool to identify the population origin of individual sturgeon outside of their natal estuaries and to determine the quantitative contributions of individual populations to coastal aggregations that are vulnerable to bycatch and other anthropogenic threats.

Determination of volatile bases in seafood using the ammonia ion selective electrode: collaborative study.

PubMed

Ellis, P C; Pivarnik, L F; Thiam, M; Ellis, P C; Pivarnik, L F; Thiam, M

2000-01-01

Nine collaborating laboratories tested a combination of 23 seafood samples for volatile bases using an ammonia ion selective electrode. Results were reported as mg NH3/100 g fish, but the method reflected levels of both ammonia and trimethylamine, which permeated the ammonia membrane. The 23 samples were broken down into 8 blind duplicate pairs, 2 Youden matched pairs, and 3 single samples covering fresh to spoiled product ranging from 8 to 82 mg NH3/100 g. Seven species were evaluated: Atlantic cod, squid, Atlantic halibut, gray sole, monkfish, dogfish, and Atlantic mackerel. The ammonia electrode assay was performed on an aqueous homogenate consisting of 95 mL distilled water and 5.0 g sample tissue. Alkaline ion strength adjusting solution (2 mL) was added to the homogenate to liberate ammonia that was sensed by the ion specific electrode and measured on a precalibrated portable meter. Repeatability standard deviations (RSDr) ranged from 4.2 to 17%; reproducibility standard deviations (RSDR) ranged from 8.8 to 21%. A standard ammonium chloride solution was provided to all laboratories to spike 3 different samples at 10 mg NH3/100 g. Recoveries of added ammonia as ammonium chloride for fresh, borderline, and spoiled samples were 88.6, 107, and 128%, respectively.

Occurrences of whale shark (Rhincodon typus Smith, 1828) in the Saint Peter and Saint Paul archipelago, Brazil.

PubMed

Hazin, F H V; Vaske Júnior, T; Oliveira, P G; Macena, B C L; Carvalho, F

2008-05-01

The Saint Peter and Saint Paul Archipelago in the central tropical Atlantic, is an important ground of whale sharks that are commonly sighted throughout the year close to the fishing boats in the adjacencies of the islands. In sightings reported between February 2000 and November 2005, the lengths of the individuals ranged between 1.8 to 14.0 m. The causes of these concentrations in the archipelago are still unclear, once there are no upwellings and plankton concentrations for feeding, and no reproductive activities were reported. Nevertheless, they could be associated to the spawning period of the abundant flying fishes, mainly in the first semester, when sightings were more frequent.

Hunter-Gatherer Responses to the 8.2 Ka Cold Event in the Fennoscandian Arctic

NASA Astrophysics Data System (ADS)

Manninen, M. A.

2014-12-01

Because of a marked influence of warm Atlantic water to primary productivity in the Barents Sea, the marine ecosystem in northernmost Fennoscandia is sensitive to disturbances in the North Atlantic oceanographic system. The 8.2 ka climate event, according to current knowledge, was triggered by a disturbance in the North Atlantic Thermohaline circulation. This suggests concurrent and strong climatic and marine cooling in the area covering the northernmost parts of Finland, Norway, and Sweden during the climate event. In this area ecosystem response to the 8.2 ka event can therefore be expected to have been prominent, which in turn should be reflected in the contemporary human socio-economic systems. A study that employs lithic technological, statistical, and spatial analyses of Late Mesolithic (ca. 8450-6850 cal BP) lithic technology and settlement configuration in the area indicates that lithic technology and settlement patterns were reorganised following the climatic and marine cooling. The studied groups changed their lithic technology as a result of developments that led to increased use of terrestrial resources and an accompanying long-distance coast/inland residential mobility pattern. Besides lithic technological changes and long-distance mobility on land, decreased marine productivity probably also explains the disappearance of semi-subterranean houses from the coast at ca. 8200 cal BP, while their reappearance after ca. 7500 cal BP can be linked to a increased influx of warm salty water into the Barents Sea. The results suggest that in the past a long period of decreased influx of Atlantic water into the Barents Sea has had disastrous consequences for the marine ecosystem. At present the Barents Sea fisheries have notable economic importance and produce, for example, over 90% of the Norwegian Atlantic cod (Gadus morhua) catch.

Latitudinal Gradient in Otolith Shape among Local Populations of Atlantic Herring (Clupea harengus L.) in Norway

PubMed Central

Libungan, Lísa Anne; Slotte, Aril; Husebø, Åse; Godiksen, Jane A.; Pálsson, Snæbjörn

2015-01-01

Otolith shape analysis of Atlantic herring (Clupea harengus) in Norwegian waters shows significant differentiation among fjords and a latitudinal gradient along the coast where neighbouring populations are more similar to each other than to those sampled at larger distances. The otolith shape was obtained using quantitative shape analysis, the outlines were transformed with Wavelet and analysed with multivariate methods. The observed morphological differences are likely to reflect environmental differences but indicate low dispersal among the local herring populations. Otolith shape variation suggests also limited exchange between the local populations and their oceanic counterparts, which could be due to differences in spawning behaviour. Herring from the most northerly location (69°N) in Balsfjord, which is genetically more similar to Pacific herring (Clupea pallasii), differed in otolith shape from all the other populations. Our results suggest that the semi-enclosed systems, where the local populations live and breed, are efficient barriers for dispersal. Otolith shape can thus serve as a marker to identify the origin of herring along the coast of Norway. PMID:26101885

Immunological discrimination of Atlantic striped bass stocks

USGS Publications Warehouse

Schill, W.B.; Dorazio, R.M.

1990-01-01

Stocks of Atlantic striped bass Morone saxatilis that were assumed to be geographically isolated during spawning showed strong antigenic differences in blood serum albumin. A discriminant function was estimated from the immunologic responses of northern (Canadian and Hudson River) and southern (Chesapeake Bay and Roanoke River) stocks to two reference antisera. The function correctly classified 92% of the northern and 95% of the southern fish in the training set. Cross-validation revealed similar percentages of correct classification for fish that were of known origin but not used to estimate the discriminant function. Monte Carlo experiments were used to evaluate the ability of the discriminant function to predict the relative contribution of northern fish in samples of various size and stock composition. Averages of predicted proportions of northern fish in the samples agreed well with actual proportions. Coefficients of variation (100 × SD/mean) in the predicted proportions ranged from 1.5 to 36% for samples of 50–400 fish that contained at least 10% northern stock. In samples that contained only 2% northern stock, however, at least 1,600 fish were required to achieve similar levels of precision.

Genetic structuring and migration patterns of Atlantic bigeye tuna, Thunnus obesus (Lowe, 1839).

PubMed

Gonzalez, Elena G; Beerli, Peter; Zardoya, Rafael

2008-09-17

Large pelagic fishes are generally thought to have little population genetic structuring based on their cosmopolitan distribution, large population sizes and high dispersal capacities. However, gene flow can be influenced by ecological (e.g. homing behaviour) and physical (e.g. present-day ocean currents, past changes in sea temperature and levels) factors. In this regard, Atlantic bigeye tuna shows an interesting genetic structuring pattern with two highly divergent mitochondrial clades (Clades I and II), which are assumed to have been originated during the last Pleistocene glacial maxima. We assess genetic structure patterns of Atlantic bigeye tuna at the nuclear level, and compare them with mitochondrial evidence. We examined allele size variation of nine microsatellite loci in 380 individuals from the Gulf of Guinea, Canary, Azores, Canada, Indian Ocean, and Pacific Ocean. To investigate temporal stability of genetic structure, three Atlantic Ocean sites were re-sampled a second year. Hierarchical AMOVA tests, RST pairwise comparisons, isolation by distance (Mantel) tests, Bayesian clustering analyses, and coalescence-based migration rate inferences supported unrestricted gene flow within the Atlantic Ocean at the nuclear level, and therefore interbreeding between individuals belonging to both mitochondrial clades. Moreover, departures from HWE in several loci were inferred for the samples of Guinea, and attributed to a Wahlund effect supporting the role of this region as a spawning and nursery area. Our microsatellite data supported a single worldwide panmictic unit for bigeye tunas. Despite the strong Agulhas Current, immigration rates seem to be higher from the Atlantic Ocean into the Indo-Pacific Ocean, but the actual number of individuals moving per generation is relatively low compared to the large population sizes inhabiting each ocean basin. Lack of congruence between mt and nuclear evidences, which is also found in other species, most likely reflects past events of isolation and secondary contact. Given the inferred relatively low number of immigrants per generation around the Cape of Good Hope, the proportions of the mitochondrial clades in the different oceans may keep stable, and it seems plausible that the presence of individuals belonging to the mt Clade I in the Atlantic Ocean may be due to extensive migrations that predated the last glaciation.

US Atlantic coast striped bass: Issues with a recovered population

USGS Publications Warehouse

Hartman, K.J.; Margraf, F.J.

2003-01-01

Striped bass, Morone saxatilis (Walbaum), is an anadromous species naturally occurring along the US Atlantic coast, which historically supported valuable commercial and recreational fisheries. In response to a near order-of-magnitude decline in landings, the Atlantic States Marine Fisheries Commission enacted a management plan in 1981 protecting fish until they could spawn at least once. By 1989, recruitment increased in natal rivers and regulations were relaxed, permitting limited fisheries by 1990. By 1995, the stock was declared fully recovered. Since the recovery, concern has increased over the health of the stocks. In the 1990s, fish in poor physical condition with dermal lesions became common in Chesapeake Bay. Pathogens of most concern in cultures from fish include the genus Mycobacterium. Coincident with declines in fish health were changes in diets, declines of preferred prey, and reduced growth and condition. Theories were suggested linking declines in condition to reductions in forage base or pathogens. Diets have changed since the 1950s and while many Chesapeake fish are infected with mycobacteria, it is still not known how or if these factors are linked. The highest priorities for research were considered to be: linking numerous local and regional studies to provide a coast-wide perspective; continuation of investigations linking population health to the prey-base; determination of the cause-effect of mycobacteria infections; and formulation of management options.

Ecological factors affecting Rainbow Smelt recruitment in the main basin of Lake Huron, 1976-2010

USGS Publications Warehouse

O'Brien, Timothy P.; Taylor, William W.; Roseman, Edward F.; Madenjian, Charles P.; Riley, Stephen C.

2014-01-01

Rainbow Smelt Osmerus mordax are native to northeastern Atlantic and Pacific–Arctic drainages and have been widely introduced throughout North America. In the Great Lakes region, Rainbow Smelt are known predators and competitors of native fish and a primary prey species in pelagic food webs. Despite their widespread distribution, importance as a prey species, and potential to negatively interact with native fish species, there is limited information concerning stock–recruitment relationships for Rainbow Smelt. To better understand recruitment mechanisms, we evaluated potential ecological factors determining recruitment dynamics for Rainbow Smelt in Lake Huron using data from bottom trawl catches. We specifically evaluated influence of stock size, environmental factors (water temperature, lake levels, and precipitation), and salmonine predation on the production of age-0 recruits from 1976 to 2010. Rainbow Smelt recruitment was negatively related to stock size exceeding 10 kg/ha, indicating that compensatory, density-dependent mortality from cannibalism or intraspecific competition was an important factor related to the production of age-0 recruits. Recruitment was positively related to spring precipitation suggesting that the amount of stream-spawning habitat as determined by precipitation was important for the production of strong Rainbow Smelt recruitment. Additionally, density of age-0 Rainbow Smelt was positively related to Lake Trout Salvelinus namaycush abundance. However, spawning stock biomass of Rainbow Smelt, which declined substantially from 1989 to 2010, was negatively associated with Lake Trout catch per effort suggesting predation was an important factor related to the decline of age-2 and older Rainbow Smelt in Lake Huron. As such, we found that recruitment of Rainbow Smelt in Lake Huron was regulated by competition with or cannibalism by older conspecifics, spring precipitation influencing stream spawning habitats, and predation by Lake Trout on age-2 and older Rainbow Smelt.

Demographic consequences of migratory stopover: linking red knot survival to horseshoe crab spawning abundance

USGS Publications Warehouse

McGowan, Conor P.; Hines, James E.; Nichols, James D.; Lyons, James E.; Smith, David; Kalasz, Kevin S.; Niles, Lawrence J.; Dey, Amanda D.; Clark, Nigel A.; Atkinson, Philip W.; Minton, Clive D.T.; Kendall, William

2011-01-01

Understanding how events during one period of the annual cycle carry over to affect survival and other fitness components in other periods is essential to understanding migratory bird demography and conservation needs. Previous research has suggested that western Atlantic red knot (Calidris canutus rufa) populations are greatly affected by horseshoe crab (Limulus polyphemus) egg availability at Delaware Bay stopover sites during their spring northward migration. We present a mass-based multistate, capturerecapture/resighting model linking (1) red knot stopover mass gain to horseshoe crab spawning abundance and (2) subsequent apparent annual survival to mass state at the time of departure from the Delaware Bay stopover area. The model and analysis use capture-recapture/resighting data with over 16,000 individual captures and 13,000 resightings collected in Delaware Bay over a 12 year period from 1997–2008, and the results are used to evaluate the central management hypothesis that red knot populations can be influenced by horseshoe crab harvest regulations as part of a larger adaptive management effort. Model selection statistics showed support for a positive relationship between horseshoe crab spawning abundance during the stopover and the probability of red knots gaining mass (parameter coefficient from the top model b = 1.71, SE = 0.46). Our analyses also supported the link between red knot mass and apparent annual survival, although average estimates for the two mass classes differed only slightly. The addition of arctic snow depth as a covariate influencing apparent survival improved the fit of the data to the models (parameter coefficient from the top model b = 0.50, SE = 0.08). Our results indicate that managing horseshoe crab resources in the Delaware Bay has the potential to improve red knot population status.

Rearing Water Treatment Induces Microbial Selection Influencing the Microbiota and Pathogen Associated Transcripts of Cod (Gadus morhua) Larvae.

PubMed

Vestrum, Ragnhild I; Attramadal, Kari J K; Winge, Per; Li, Keshuai; Olsen, Yngvar; Bones, Atle M; Vadstein, Olav; Bakke, Ingrid

2018-01-01

We have previously shown that K-selection and microbial stability in the rearing water increases survival and growth of Atlantic cod ( Gadus morhua ) larvae, and that recirculating aquaculture systems (RAS) are compatible with this. Here, we have assessed how water treatment influenced the larval microbiota and host responses at the gene expression level. Cod larvae were reared with two different rearing water systems: a RAS and a flow-through system (FTS). The water microbiota was examined using a 16S rDNA PCR/DGGE strategy. RNA extracted from larvae at 8, 13, and 17 days post hatching was used for microbiota and microarray gene expression analysis. Bacterial cDNA was synthesized and used for 16S rRNA amplicon 454 pyrosequencing of larval microbiota. Both water and larval microbiota differed significantly between the systems, and the larval microbiota appeared to become more dissimilar between systems with time. In total 4 phyla were identified for all larvae: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The most profound difference in larval microbiota was a high abundance of Arcobacter (Epsilonproteobacteria) in FTS larvae (34 ± 9% of total reads). Arcobacter includes several species that are known pathogens for humans and animals. Cod larval transcriptome responses were investigated using an oligonucleotide gene expression microarray covering approximately 24,000 genes. Interestingly, FTS larvae transcriptional profiles revealed an overrepresentation of upregulated transcripts associated with responses to pathogens and infections, such as c1ql3-like , pglyrp-2-like and zg16, compared to RAS larvae. In conclusion, distinct water treatment systems induced differences in the larval microbiota. FTS larvae showed up-regulation of transcripts associated with responses to microbial stress. These results are consistent with the hypothesis that RAS promotes K-selection and microbial stability by maintaining a microbial load close to the carrying capacity of the system, and ensuring long retention times for both bacteria and water in the system.

Structural and biophysical analysis of interactions between cod and human uracil-DNA N-glycosylase (UNG) and UNG inhibitor (Ugi)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Assefa, Netsanet Gizaw; Niiranen, Laila; University of Turku, FIN-20014 Turku

2014-08-01

A structural and biophysical study of the interactions between cod and human uracil-DNA N-glycosylase (UNG) and their inhibitor Ugi is presented. The stronger interaction between cod UNG and Ugi can be explained by a greater positive electrostatic surface potential. Uracil-DNA N-glycosylase from Atlantic cod (cUNG) shows cold-adapted features such as high catalytic efficiency, a low temperature optimum for activity and reduced thermal stability compared with its mesophilic homologue human UNG (hUNG). In order to understand the role of the enzyme–substrate interaction related to the cold-adapted properties, the structure of cUNG in complex with a bacteriophage encoded natural UNG inhibitor (Ugi)more » has been determined. The interaction has also been analyzed by isothermal titration calorimetry (ITC). The crystal structure of cUNG–Ugi was determined to a resolution of 1.9 Å with eight complexes in the asymmetric unit related through noncrystallographic symmetry. A comparison of the cUNG–Ugi complex with previously determined structures of UNG–Ugi shows that they are very similar, and confirmed the nucleotide-mimicking properties of Ugi. Biophysically, the interaction between cUNG and Ugi is very strong and shows a binding constant (K{sub b}) which is one order of magnitude larger than that for hUNG–Ugi. The binding of both cUNG and hUNG to Ugi was shown to be favoured by both enthalpic and entropic forces; however, the binding of cUNG to Ugi is mainly dominated by enthalpy, while the entropic term is dominant for hUNG. The observed differences in the binding properties may be explained by an overall greater positive electrostatic surface potential in the protein–Ugi interface of cUNG and the slightly more hydrophobic surface of hUNG.« less

Rearing Water Treatment Induces Microbial Selection Influencing the Microbiota and Pathogen Associated Transcripts of Cod (Gadus morhua) Larvae

PubMed Central

Vestrum, Ragnhild I.; Attramadal, Kari J. K.; Winge, Per; Li, Keshuai; Olsen, Yngvar; Bones, Atle M.; Vadstein, Olav; Bakke, Ingrid

2018-01-01

We have previously shown that K-selection and microbial stability in the rearing water increases survival and growth of Atlantic cod (Gadus morhua) larvae, and that recirculating aquaculture systems (RAS) are compatible with this. Here, we have assessed how water treatment influenced the larval microbiota and host responses at the gene expression level. Cod larvae were reared with two different rearing water systems: a RAS and a flow-through system (FTS). The water microbiota was examined using a 16S rDNA PCR/DGGE strategy. RNA extracted from larvae at 8, 13, and 17 days post hatching was used for microbiota and microarray gene expression analysis. Bacterial cDNA was synthesized and used for 16S rRNA amplicon 454 pyrosequencing of larval microbiota. Both water and larval microbiota differed significantly between the systems, and the larval microbiota appeared to become more dissimilar between systems with time. In total 4 phyla were identified for all larvae: Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. The most profound difference in larval microbiota was a high abundance of Arcobacter (Epsilonproteobacteria) in FTS larvae (34 ± 9% of total reads). Arcobacter includes several species that are known pathogens for humans and animals. Cod larval transcriptome responses were investigated using an oligonucleotide gene expression microarray covering approximately 24,000 genes. Interestingly, FTS larvae transcriptional profiles revealed an overrepresentation of upregulated transcripts associated with responses to pathogens and infections, such as c1ql3-like, pglyrp-2-like and zg16, compared to RAS larvae. In conclusion, distinct water treatment systems induced differences in the larval microbiota. FTS larvae showed up-regulation of transcripts associated with responses to microbial stress. These results are consistent with the hypothesis that RAS promotes K-selection and microbial stability by maintaining a microbial load close to the carrying capacity of the system, and ensuring long retention times for both bacteria and water in the system. PMID:29765364

Feeding Ecology of Northeast Atlantic Mackerel, Norwegian Spring-Spawning Herring and Blue Whiting in the Norwegian Sea.

PubMed

Bachiller, Eneko; Skaret, Georg; Nøttestad, Leif; Slotte, Aril

2016-01-01

The Norwegian spring-spawning (NSS) herring (Clupea harengus), blue whiting (Micromesistius poutassou) and Northeast Atlantic (NEA) mackerel (Scomber scombrus) are extremely abundant pelagic planktivores that feed in the Norwegian Sea (NS) during spring and summer. This study investigated the feeding ecology and diet composition of these commercially important fish stocks on the basis of biological data, including an extensive set of stomach samples in combination with hydrographical data, zooplankton samples and acoustic abundance data from 12 stock monitoring surveys carried out in 2005-2010. Mackerel were absent during the spring, but had generally high feeding overlap with herring in the summer, with a diet mainly based on calanoid copepods, especially Calanus finmarchicus, as well as a similar diet width. Stomach fullness in herring diminished from spring to summer and feeding incidence was lower than that of mackerel in summer. However, stomach fullness did not differ between the two species, indicating that herring maintain an equally efficient pattern of feeding as mackerel in summer, but on a diet that is less dominated by copepods and is more reliant on larger prey. Blue whiting tended to have a low dietary overlap with mackerel and herring, with larger prey such as euphausiids and amphipods dominating, and stomach fullness and feeding incidence increasing with length. For all the species, feeding incidence increased with decreasing temperature, and for mackerel so did stomach fullness, indicating that feeding activity is highest in areas associated with colder water masses. Significant annual effects on diet composition and feeding-related variables suggested that the three species are able to adapt to different food and environmental conditions. These annual effects are likely to have an important impact on the predation pressure on different plankton groups and the carrying capacity of individual systems, and emphasise the importance of regular monitoring of pelagic fish diets.

Estimating the effective number of breeders from single parr samples for conservation monitoring of wild populations of Atlantic salmon Salmo salar.

PubMed

Bacles, C F E; Bouchard, C; Lange, F; Manicki, A; Tentelier, C; Lepais, O

2018-03-01

This study assesses whether the effective number of breeders (N b ) can be estimated using a time and cost-effective protocol using genetic sibship reconstruction from a single sample of young-of-the-year (YOY) for the purposes of Atlantic salmon Salmo salar population monitoring. N b was estimated for 10 consecutive reproductive seasons for S. salar in the River Nivelle, a small population located at the rear-edge of the species distribution area in France, chronically under its conservation limit and subjected to anthropogenic and environmental changes. Subsampling of real and simulated data showed that accurate estimates of N b can be obtained from YOY genotypes, collected at moderate random sampling intensity, achievable using routine juvenile electrofishing protocols. Spatial bias and time elapsed since spawning were found to affect estimates, which must be accounted for in sampling designs. N b estimated in autumn for S. salar in the River Nivelle was low and variable across years from 23 (95% C.I. 14-41) to 75 (53-101) and was not statistically correlated with the estimated number of returning adults, but it was positively correlated with the estimated number of YOY at age 9 months. N b was found to be lower for intermediate levels of redd aggregation, suggesting that the strength of the competition between males to access females affects reproductive success variance depending on redd spatial configuration. Thus, environmental factors such as habitat availability and quality for spawning and YOY development predominate over demographic ones (number of returning adults) in driving long-term population viability for S. salar in the River Nivelle. This study showcases N b as an integrated parameter, encompassing demographic and ecological information about a reproductive event, relevant to the assessment of both short-term effects of management practices and long-term population conservation status. © 2018 The Fisheries Society of the British Isles.

The Two-Column Aerosol Project: Phase I - Overview and Impact of Elevated Aerosol Layers on Aerosol Optical Depth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berg, Larry K.; Fast, Jerome D.; Barnard, James C.

2016-01-08

The Two-Column Aerosol Project (TCAP), which was conducted from June 2012 through June 2013, was a unique field study that was designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere at a number of altitudes, from near the surface to as high as 8 km, within two atmospheric columns; one located near the coast of North America (over Cape Cod, MA) and a second over the Atlantic Ocean several hundredmore » kilometers from the coast. TCAP included the yearlong deployment of the U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) that was located at the base of the Cape Cod column, as well as summer and winter aircraft intensive observation periods of the ARM Aerial Facility. One important finding from TCAP is the relatively common occurrence (on four of six nearly cloud-free flights) of elevated aerosol layers in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total aerosol optical depth (AOD) observed in the column. Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning aerosol and nitrate compared to the aerosol found near the surface.« less

A comparative study of quality and safety of Atlantic cod (Gadus morhua) fillets during cold storage, as affected by different thawing methods of pre‐rigor frozen headed and gutted fish

PubMed Central

Jónsson, Ásbjörn; Backi, Christoph Josef; Lunestad, Bjørn Tore; Karlsdóttir, Magnea G

2017-01-01

Abstract BACKGROUND The catch of marine whitefish is typically seasonal, whereas the land‐based processing industry has a need for all‐year stable supply of raw materials. This challenge can be met by applying fish frozen at sea. When using frozen fish, the methods employed for thawing may influence the safety and quality of the final product. This study aimed to investigate the applicability of novel thawing strategies in order to provide an all‐year supply of high‐quality and safe cod products. RESULTS Comparative investigations of quality and safety factors after thawing in water, with and without air circulation, and contact thawing were performed. The parameters included water‐holding capacity, thawing loss, drip loss, cooking yield, sensory evaluation and microbiological analyses (including total volatile bases nitrogen). Water thawing with air circulation provided faster thawing than water thawing without air circulation and contact thawing. For all three methods, the quality of the thawed fish was acceptable and the shelf life of the fillets during chilled storage was between 10 and 14 days post‐filleting. CONCLUSION The results show that controlled freezing of cod, followed by appropriate thawing, may provide the processing industry with an all‐year delivery of raw materials, without compromising quality and safety of the final product. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:28862323

Chemical quality of ground water on Cape Cod, Massachusetts

USGS Publications Warehouse

Frimpter, M.H.; Gay, F.B.

1979-01-01

Cape Cod is a 440 square mile hook-shaped peninsula which extends 40 miles into the Atlantic. Freshwater in Pleistocene sand and gravel deposits is the source of supply for nearly 100 municipal and thousands of private domestic wells. Most ground water on Cape Cod is of good chemical quality for drinking and other uses. It is characteristically low in dissolved solids and is soft. In 90 percent of the samples analyzed, dissolved solids were less than 100 mg/l (milligrams per liter) and pH was less than 7.0. Highway deicing salt, sea-water flooding due to storms , and saltwater intrusion due to ground-water withdrawal are sources of sodium chloride contamination. Chloride concentrations have increased from 20 to 140 mg/l, owing to saltwater intrusion at Provincetown 's wells in Truro. In Yarmouth, contaminated ground water near a salt-storage area contained as much as 1,800 mg/l chloride. Heavy metals, insecticides, and herbicides were not found at concentrations above the U.S. Environmental Protection Agency 's recommended limits for public drinking-water supplies, but iron and manganese in some samples exceeded those limits. Ninety percent of 84 samples analyzed for nitrate reported as nitrogen contained less than 1.3 mg/l and 80 percent contained 0.5 mg/l or less of nitrate as nitrogen. Water containing nitrogen in excess of 0.5 mg/l has probably been affected by municipal or domestic sewage or fertilizer, and water with less than this amount may have been affected by them. (Woodard-USGS)

The Two-Column Aerosol Project: Phase I - Overview and Impact of Elevated Aerosol Layers on Aerosol Optical Depth

NASA Technical Reports Server (NTRS)

Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; Burton, Sharon P.; Cairns, Brian; Chand, Duli; Comstock, Jennifer M.; Dunagan, Stephen; Ferrare, Richard A.; Flynn, Connor J.;

The Two-Column Aerosol Project: Phase I—Overview and impact of elevated aerosol layers on aerosol optical depth

NASA Astrophysics Data System (ADS)

Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; Burton, Sharon P.; Cairns, Brian; Chand, Duli; Comstock, Jennifer M.; Dunagan, Stephen; Ferrare, Richard A.; Flynn, Connor J.; Hair, Johnathan W.; Hostetler, Chris A.; Hubbe, John; Jefferson, Anne; Johnson, Roy; Kassianov, Evgueni I.; Kluzek, Celine D.; Kollias, Pavlos; Lamer, Katia; Lantz, Kathleen; Mei, Fan; Miller, Mark A.; Michalsky, Joseph; Ortega, Ivan; Pekour, Mikhail; Rogers, Ray R.; Russell, Philip B.; Redemann, Jens; Sedlacek, Arthur J.; Segal-Rosenheimer, Michal; Schmid, Beat; Shilling, John E.; Shinozuka, Yohei; Springston, Stephen R.; Tomlinson, Jason M.; Tyrrell, Megan; Wilson, Jacqueline M.; Volkamer, Rainer; Zelenyuk, Alla; Berkowitz, Carl M.

2016-01-01

The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had aerosol layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the aerosol chemical composition and optical properties, no systematic differences between the two columns were observed.

Gender Specific Reproductive Strategies of an Arctic Key Species (Boreogadus saida) and Implications of Climate Change

PubMed Central

Nahrgang, Jasmine; Varpe, Øystein; Korshunova, Ekaterina; Murzina, Svetlana; Hallanger, Ingeborg G.; Vieweg, Ireen; Berge, Jørgen

2014-01-01

The Arctic climate is changing at an unprecedented rate. What consequences this may have on the Arctic marine ecosystem depends to a large degree on how its species will respond both directly to elevated temperatures and more indirectly through ecological interactions. But despite an alarming recent warming of the Arctic with accompanying sea ice loss, reports evaluating ecological impacts of climate change in the Arctic remain sparse. Here, based upon a large-scale field study, we present basic new knowledge regarding the life history traits for one of the most important species in the entire Arctic, the polar cod (Boreogadus saida). Furthermore, by comparing regions of contrasting climatic influence (domains), we present evidence as to how its growth and reproductive success is impaired in the warmer of the two domains. As the future Arctic is predicted to resemble today's Atlantic domains, we forecast changes in growth and life history characteristics of polar cod that will lead to alteration of its role as an Arctic keystone species. This will in turn affect community dynamics and energy transfer in the entire Arctic food chain. PMID:24871481

Potential fitness benefits from mate selection in the Atlantic cod (Gadus morhua).

PubMed

Rudolfsen, G; Figenschou, L; Folstad, I; Nordeide, J T; Søreng, E

2005-01-01

Little evidence of benefits from female mate choice has been found when males provide no parental care or resources. Yet, good genes models of sexual selection suggest that elaborated male sexual characters are reliable signals of mate quality and that the offspring of males with elaborate sexual ornaments will perform better than those of males with less elaborate ornaments. We used cod (Gadus morhua L.), an externally fertilizing species where males provide nothing but sperm, to examine the potential of optimal mate selection with respect to offspring survival. By applying in vitro fertilizations, we crossed eight females with nine males in all possible combinations and reared each of the 72 sib groups. We found that offspring survival was dependent on which female was mated with which male and that optimal mate selection has the potential to increase mean offspring survival from 31.9 to 55.6% (a 74% increase). However, the size of the male sexual ornaments and sperm quality (i.e. sperm velocity and sperm density) could not predict offspring survival. Thus, even if there may be large fitness benefits of mate selection, we might not yet have identified the male characteristics generating high offspring survival.

Signatures of the collapse and incipient recovery of an overexploited marine ecosystem

PubMed Central

Thompson, Patrick L.; Ball, R. Aaron; Fortin, Marie-Josée; Gouhier, Tarik C.; Link, Heike; Moritz, Charlotte; Nenzen, Hedvig; Stanley, Ryan R. E.; Taranu, Zofia E.; Gonzalez, Andrew; Guichard, Frédéric; Pepin, Pierre

2017-01-01

The Northwest Atlantic cod stocks collapsed in the early 1990s and have yet to recover, despite the subsequent establishment of a continuing fishing moratorium. Efforts to understand the collapse and lack of recovery have so far focused mainly on the dynamics of commercially harvested species. Here, we use data from a 33-year scientific trawl survey to determine to which degree the signatures of the collapse and recovery of the cod are apparent in the spatial and temporal dynamics of the broader groundfish community. Over this 33-year period, the groundfish community experienced four phases of change: (i) a period of rapid, synchronous biomass collapse in most species, (ii) followed by a regime shift in community composition with a concomitant loss of functional diversity, (iii) followed in turn by periods of slow compositional recovery, and (iv) slow biomass growth. Our results demonstrate how a community-wide perspective can reveal new aspects of the dynamics of collapse and recovery unavailable from the analysis of individual species or a combination of a small number of species. Overall, we found evidence that such community-level signals should be useful for designing more effective management strategies to ensure the persistence of exploited marine ecosystems. PMID:28791149

Genetic Structure of Bluefin Tuna in the Mediterranean Sea Correlates with Environmental Variables

PubMed Central

Riccioni, Giulia; Stagioni, Marco; Landi, Monica; Ferrara, Giorgia; Barbujani, Guido; Tinti, Fausto

2013-01-01

Background Atlantic Bluefin Tuna (ABFT) shows complex demography and ecological variation in the Mediterranean Sea. Genetic surveys have detected significant, although weak, signals of population structuring; catch series analyses and tagging programs identified complex ABFT spatial dynamics and migration patterns. Here, we tested the hypothesis that the genetic structure of the ABFT in the Mediterranean is correlated with mean surface temperature and salinity. Methodology We used six samples collected from Western and Central Mediterranean integrated with a new sample collected from the recently identified easternmost reproductive area of Levantine Sea. To assess population structure in the Mediterranean we used a multidisciplinary framework combining classical population genetics, spatial and Bayesian clustering methods and a multivariate approach based on factor analysis. Conclusions FST analysis and Bayesian clustering methods detected several subpopulations in the Mediterranean, a result also supported by multivariate analyses. In addition, we identified significant correlations of genetic diversity with mean salinity and surface temperature values revealing that ABFT is genetically structured along two environmental gradients. These results suggest that a preference for some spawning habitat conditions could contribute to shape ABFT genetic structuring in the Mediterranean. However, further studies should be performed to assess to what extent ABFT spawning behaviour in the Mediterranean Sea can be affected by environmental variation. PMID:24260341

Influence of sperm and phytoplankton on spawning in the echinoid Lytechinus variegatus.

PubMed

Reuter, Kim E; Levitan, Don R

2010-12-01

The cues triggering large-scale broadcast-spawning events in marine invertebrates are not fully understood. Using the sea urchin Lytechinus variegatus, we tested the effectiveness of a variety of potential spawning cues in eliciting a spawning response. In the laboratory, during two consecutive spawning seasons, about 400 isolated sea urchins were exposed to phytoplankton, sperm, or eggs, singly or in combination. The likelihood of spawning, time to spawning, and spawning behavior were recorded for both sexes. Sperm was most successful at inducing spawning. No response to eggs was noted. Phytoplankton alone did not trigger spawning, but when a phytoplankton cue was followed by the addition of sperm, spawning behavior was induced, the time between addition of sperm and spawning was reduced, and the variance among individuals in the time of spawning initiation was reduced. Males spawned sooner in response to cues than females and rarely spawned spontaneously in phytoplankton or control treatments. A semilunar pattern in the sensitivity to spawning cues was noted. During time periods when sea urchins were less ripe, the ratio of spawning males to spawning females increased. Our results indicate that seasonal and lunar cycles, together with the presence of phytoplankton, increase the sensitivity of these sea urchins to spawning cues and the precision of their responses to conspecific sperm.

History of salmon in the Great Lakes, 1850-1970

USGS Publications Warehouse

Parsons, John W.

1973-01-01

This history of the salmon in the Great Lakes describes the decline and extinction of the Atlantic salmon (Salmo salar) in Lake Ontario in the 1800's; the failure to establish, by salmon culture, permanent or sizable populations of Atlantic or Pacific salmon in any of the Great Lakes in 1867-1965; and the success of the plantings of coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytsha) in the Great Lakes, in 1966-70 -- particularly in Lake Michigan. Despite plantings of 5 million fry and fingerlings from Lake Ontario stocks in 1866-84, the native Atlantic salmon in Lake Ontario became extinct in the late 1800's primarily because tributaries in which they spawned were blocked by mill dams. Plantings of 13 million chinook salmon and landlocked and anadromous forms of Atlantic salmon in Lake Ontario and the other Great Lakes in 1873-1947 failed completely. The first species to develop a self-sustaining population was the pink salmon (O. gorbuscha), which was planted in Lake Superior in 1956; however, it has not become abundant. A salmon fishery finally was established when 15 million coho salmon and 6 million chinook salmon were planted as smolt in the Great Lakes in 1966-70. In 1970, for example, 576,000 coho salmon (12% of those planted in 1969) were caught by anglers in Lake Michigan. Most weighed 5 to 10 pounds (2.3-4.5 kg). Sport fishing for salmon was fair in Lakes Superior and Huron, and poor in Lakes Erie and Ontario. By 1970, natural reproduction of coho, chinook, pink, and kokanee (O. nerka) salmon had occurred in some tributaries of one or more of the upper three Great Lakes. It is expected, however, that the sport fishery will continue to be supported almost entirely by planted fish.

The biology and fisheries of European hake, Merluccius merluccius, in the north-east Atlantic.

PubMed

Murua, Hilario

2010-01-01

The aim of this chapter is to review the biology and fishery, including the management, of European hake in the north-east Atlantic. The European hake is widely distributed throughout the north-east Atlantic, from Norway in the north to the Guinea Gulf in the south, and throughout the Mediterranean and Black Sea, being more abundant from the British Isles to the south of Spain. In this area, ICES (International Council for the Exploration of the Sea) recognises the existence of two stocks: the northern stock and the southern stock. Both stocks have been extensively and intensively harvested and since the beginning of the 90s have been considered to be outside safe biological limits. The northern stock, however, is currently considered to lie within safe biological limits. In any case, recovery plans were implemented for the northern stock in 2004 and for the southern stock in 2006. Despite its commercial importance, knowledge of the biology and ecology of the European hake in the North Atlantic is still quite scarce. For example, recent investigations suggest that European hake grows much faster, by a factor of two, than was considered previously. This faster growth also affects the maturity-at-age pattern of hake and the agreed maturity-at-age ogive used in the assessments. European hake is a top predator in the demersal community in the north-east Atlantic area; mainly preying on blue whiting, horse mackerel and other cupleids. In relation to the reproductive biology, European hake is considered to be a batch spawner species with indeterminate fecundity and spawning activity all year round. All these characteristics could, in turn, be interpreted as European hake adopting a more opportunistic life strategy, which is unusual for a gadoid and demersal species, and raises several questions about hake biology and ecology that require further investigation. Copyright © 2010 Elsevier Ltd. All rights reserved.

Deep-water fisheries at the Atlantic Frontier

NASA Astrophysics Data System (ADS)

Gordon, J. D. M.

2001-05-01

The deep sea is often thought of as a cold, dark and uniform environment with a low-fish biomass, much of which is highly adapted for life in a food-poor environment. While this might be true of the pelagic fish living in the water column, it is certainly not true of the demersal fish which live on or close to the bottom on the continental slopes around the British Isles (the Atlantic Frontier). These fish are currently being commercially exploited. There is growing evidence to support the view that success of the demersal fish assemblages depends on the pelagic or benthopelagic food sources that impinge both vertically and horizontally onto the slope. There are several quite separate and distinct deep-water fisheries on the Atlantic Frontier. It is a physical barrier, the Wyville-Thomson Ridge, which results in the most significant division of the fisheries. The Ridge, which has a minimum depth of about 500 m, separates the warmer deep Atlantic waters from the much colder Norwegian Sea water and as a result, the deep-water fisheries to the west of the Hebrides and around the offshore banks are quite different from those of the Faroe-Shetland Channel (West of Shetland). The fisheries to the West of the Hebrides can be further divided by the fishing method used into bottom trawl, semipelagic trawl and longline. The bottom-trawl fisheries extend from the shelf-slope break down to about 1700 m and the target species varies with depth. The smallest vessels in the fleet fish on the upper slope, where an important target species is the anglerfish or monkfish ( Lophius spp.). On the mid-slope the main target species are blue ling ( Molva dypterygia) and roundnose grenadier ( Coryphaenoides rupestris), with bycatches of black scabbardfish ( Aphanopus carbo) and deep-water sharks. On the lower slope orange roughy ( Hoplostethus atlanticus) is an important target species. The major semipelagic trawl fishery is a seasonal fishery on spawning aggregations of blue whiting ( Micromesistius poutassou). The other semipelagic fishery is on spawning aggregations of the greater silver smelt or argentine ( Argentina silus). Spanish and UK vessels that target mainly hake ( Merluccius merluccius) and a Norwegian fleet that targets ling ( Molva molva), blue ling and tusk ( Brosme brosme) dominate the upper slope longline fishery. West of Shetland, the fishery on the upper slope has some similarities with that of the Hebridean slope, with anglerfish and blue ling being important target species. A quite different fishery occurs in the transition zone between the Atlantic and Norwegian Sea waters. Here the main target species is Greenland halibut ( Reinhardtius hippoglossoides). Below the transition zone biomass decreases rapidly and there is no fishery. It is generally agreed that many deep-water species have slow growth, a high age at first maturity and a low fecundity, which makes them vulnerable to over-exploitation. Other features of these fishes such as high mortality of discards and escapees will add to the problems. Despite this the only management procedures in place are general limitation of effort measures within the area of jurisdiction of the European Union.

Cloning and characterization of transferrin cDNA and rapid detection of transferrin gene polymorphism in rainbow trout (Oncorhynchus mykiss).

PubMed

Tange, N; Jong-Young, L; Mikawa, N; Hirono, I; Aoki, T

1997-12-01

A cDNA clone of rainbow trout (Oncorhynchus mykiss) transferrin was obtained from a liver cDNA library. The 2537-bp cDNA sequence contained an open reading frame encoding 691 amino acids and the 5' and 3' noncoding regions. The amino acid sequences at the iron-binding sites and the two N-linked glycosylation sites, and the cysteine residues were consistent with known, conserved vertebrate transferrin cDNA sequences. Single N-linked glycosylation sites existed on the N- and C-lobe. The deduced amino acid sequence of the rainbow trout transferrin cDNA had 92.9% identities with transferrin of coho salmon (Oncorhynchus kisutch); 85%, Atlantic salmon (Salmo salar); 67.3%, medaka (Oryzias latipes); 61.3% Atlantic cod (Gadus morhua); and 59.7%, Japanese flounder (Paralichthys olivaceus). The long and accurate polymerase chain reaction (LA-PCR) was used to amplify approximately 6.5 kb of the transferrin gene from rainbow trout genomic DNA. Restriction fragment length polymorphisms (RFLPs) of the LA-PCR products revealed three digestion patterns in 22 samples.

The Distribution of Dissolved Barium from US GEOTRACES cruises in the North Atlantic and Eastern Tropical South Pacific

NASA Astrophysics Data System (ADS)

Shiller, A. M.; Grissom, K.

2014-12-01

Interest in the oceanic geochemistry of barium (Ba) stems from a variety of reasons including its use as a paleo-productivity indicator, its chemical similarity to Ra, and its utility as a water source tracer. To better constrain these uses of Ba, we have obtained trace element clean samples from both the North Atlantic and Eastern Pacific US GEOTRACES cruises. Analytical work on the Pacific samples is proceeding while work on the Atlantic samples is complete. For the Pacific, 36 stations were occupied from Peru to Tahiti. For the Atlantic, dissolved Ba was determined at 32 stations across the North Atlantic during US cruises GT10 and GT11 along the meridional transect from Lisbon to the Cape Verde Islands and the zonal transect from Cape Cod to the Mauritanian coast. In the Atlantic, the general distribution of dissolved Ba exhibits a vertical bifurcation at approximately 500 m into shallow versus deep water. The greatest variation is found on the eastern side of the basin with concentrations ranging from 35 nmol/kg at the near surface (100 m) to over 83 nmol/kg at depth. A reduction of Ba in excess of 20% compared to the average of mesopelagic depths less than 500 m is observed within the Canary Current upwelling zone east of the Cape Verde Islands and accompanied to some extent by a subsequent regeneration at depth. Below 500 m, dissolved Ba correlates well with dissolved Si, whereas the correlation with alkalinity is poor at depth and shows a decoupling above 500 m. There is evidence of hydrothermal Ba input at the TAG vent system of the Mid-Atlantic Ridge along transect GT11 as indicated by the rapid increase in the dissolved Ba below 2500 m in conjunction with increases in Fe and Mn. In addition to the hydrothermal source, a near surface (~40 m) maximum of 51 nmol/kg is found along the continental slope of North America in correspondence with a minimum surface salinity (34.75) and increased dissolved manganese indicating either fluvial or sediment input; however, a similar input is not evident along the North African continental margin. We will contrast the Atlantic distribution with the Pacific as data become available.

Impact of the North Atlantic Oscillation on the trans-Atlantic migrations of the European eel (Anguilla anguilla)

NASA Astrophysics Data System (ADS)

Kettle, A. James; Bakker, Dorothee C. E.; Haines, Keith

2008-09-01

Glass eel catches and FAO (Food and Agricultural Organization) landings of the European freshwater eel (Anguilla anguilla) show a decrease over the past 20 years. The long-term trends in the time series mask an interannual fluctuation, which becomes apparent on the application of a high-pass filter and autocorrelation analysis. Both the FAO landings and the glass eel catches show interannual fluctuations with a repeat period of 6-8 years, similar to the period of the North Atlantic Oscillation (NAO). Most glass eel catch monitoring stations are in phase. The glass eel catches show a significant negative correlation with the NAO lagged by 0-2 years, consistent with the hypothesis that the positive NAO phase has an adverse impact on the larval survival in and migration from the Sargasso Sea spawning location, one year prior to the arrival of the glass eels in Europe and North Africa. The FAO landings can be divided into two groups of different phase that have an approximate correspondence to the NAO dipole in winter rainfall in Europe and North Africa. One group (P) comprises Denmark, Ireland, Morocco, Netherlands, Norway, Sweden, Tunisia, and the United Kingdom, and the other group (N) comprises France, Germany, Italy, Poland, Portugal, Spain, and Turkey. At least for the interannual fluctuations, the success of the glass eel fishery (and eel recruitment) may be coupled with the number of migrating silver eels from the N group of countries and uncoupled with the P group of countries.

Size selection from fishways and potential evolutionary responses in a threatened Atlantic salmon population

USGS Publications Warehouse

Maynard, George A.; Kinnison, M.T.; Zydlewski, Joseph D.

2017-01-01

The evolutionary effects of harvest on wild fish populations have been documented around the world; however, sublethal selective pressures can also cause evolutionary changes in phenotypes. For migratory fishes, passage facilities may represent instances of nonlethal selective pressure. Our analysis of 6 years of passage data suggests that certain fish passage facilities on the Penobscot River have been exerting selective pressure against large-bodied, anadromous Atlantic salmon (Salmo salar). At the second and third dams in the river, a 91-cm salmon was 21%–27% and 12%–16% less likely to pass than a 45-cm salmon, respectively. Fish size positively influences egg survival and number and is a heritable trait. Therefore, in a wild-reproducing population, exclusion of large fish from spawning areas may have population-level impacts. In the Penobscot River, most returning adults derive from a hatchery program that collects its broodstock after passing the first dam in the river. Analysis of fork lengths of salmon returning to the Penobscot River from 1978 to 2012 provided mixed support for evolution of size at maturity in different age classes in a pattern that may be expected from interactions with conservation hatchery operations. Additionally, slow-maturing and iteroparous individuals that represent the largest salmon size classes were essentially lost from the population during that time, and Penobscot River fish have shorter fork lengths at maturity than Atlantic salmon in undammed systems.

Ichthyoplankton spatial pattern in the inner shelf off Bahía Blanca Estuary, SW Atlantic Ocean

NASA Astrophysics Data System (ADS)

Hoffmeyer, Mónica Susana; Clara, Menéndez María; Florencia, Biancalana; Mabel, Nizovoy Alicia; Ramón, Torres Eduardo

2009-09-01

This study focuses on the composition, abundance and distribution of ichthyoplankton in the inner shelf area off Bahía Blanca Estuary on the SW Atlantic Ocean during late spring. Eggs and larvae of Brevoortia aurea, Engraulis anchoita, Parona signata, Sciaenidae spp. - such as Cynoscion guatucupa and Micropogonias furnieri -, and Odontesthes argentinensis were found. Species richness was low probably as a result of season and shallow depths. Ichthyoplankton abundance reached values close to 10 000 per 10 m -3 (eggs) and 4000 per 10 m -3 (larvae) and displayed a spatial distribution pattern with maximum abundance values restricted to a band parallel to the coast. Differences between egg and larval patterns, probably derived from a different displacement and hydrodynamic behavior, were observed. Egg and larvae distribution patterns were found related with spawning areas and to directly depend on salinity and mesozooplankton. The larvae distribution pattern, in particular, was found to inversely depend on particulate organic carbon. In addition, the geographic location of egg and larvae maxima strongly coincided with a saline front reported for this area in springtime, thus suggesting a direct relationship with it.

A Spurious Correlation in an Interpopulation Comparison of Atlantic Salmon Life Histories.

PubMed

Myers, Ransom A; Hutchings, Jeffrey A

1987-12-01

We tested two hypotheses concerning geographical variation in Atlantic salmon (Salmo salar) life histories: (1) mean age at first reproduction is positively correlated with growth rate at sea and (2) within-population variation in age at first reproduction first increases and then decreases with latitude. Data on growth and age at first reproduction were compiled from 41 populations in eastern North America. Data reliability was checked by a redetermination of ages based on scale examination. The proportion of fish that were incorrectly aged was small (°0.7%); however, aging errors were primarily of one kind; salmon that had previously spawned were misclassified as virgin fish of an older age class. Growth rate at sea was found not to be positively correlated with age at maturation. Schaffer and Elson's (1975) positive correlation between growth and age at first reproduction can be attributed to a subtle statistical artifact caused by aging errors. We also found that within-population variation of age at maturation was not related to latitude. We conclude that tests of life history theories should not assume constancy in life history traits, such as mortality, among populations. © 1987 by the Ecological Society of America.

Intraovum infection caused by Flavobacterium psychrophilum among eggs from captive Atlantic salmon broodfish

USGS Publications Warehouse

Cipriano, R.C.

2005-01-01

This study indicated that the bacterium Flavobacterium psychrophilum induced an infection within eggs of Atlantic salmon Salmo salar that were held at federal New England restoration facilities. The pathogen, which originated from the Connecticut, Penobscot, Machias, East Machias, Dennys, Narraguagus, and Sheepscot rivers, was obtained from these eggs at concentrations that ranged from 5.0 ?? 102 to 2.5 ?? 108 colony-forming units per gram of egg, despite successive treatments with povidone iodine (I2). Treatments consisted of 50 mg/L of water for 30 min, then 100 mg/L for 10 min, followed at the eyed egg stage by 100 mg/L for 60 min. Collectively, 63% of the egg lots (77 of 122) obtained from paired matings of these captive broodfish were infected; 39% of these lots contained 10 or fewer infected eggs (60 eggs sampled per lot), and less than 10% of the lots contained more than 20 positive eggs. Consequently, standard iodophor disinfection procedures were ineffective. Eggs were positive from each of the river-specific captive brood populations during both of the spawning cycles that were studied. I concluded that F. psychrophilum established an intraovum infection that was prevalent among captive brood lots from different New England watersheds.

Upstream migratory behaviour of wild and ranched Atlantic salmon Salmo salar at a natural obstacle in a coastal spate river.

PubMed

Kennedy, R J; Moffett, I; Allen, M M; Dawson, S M

2013-09-01

The upstream migratory behaviour of wild and ranched Atlantic salmon Salmo salar in a small Irish coastal spate river was investigated using acoustic telemetry. Prespawning migratory behaviour was investigated including movement patterns at a large natural waterfall in the lower reaches of the river. A strong diurnal pattern was observed for upstream migrants at the waterfall indicative of the need for daylight to ascend this complex natural obstacle to migration. Successful passage of the waterfall was also associated with distinct environmental conditions and no difference in migratory ability was detected between wild and ranched origin S. salar. Wild S. salar tended to exhibit a non-erratic, stepwise upstream migration pattern after ascending the waterfall while ranched S. salar had an increased probability of displaying more erratic migratory behaviour. Wild S. salar penetrated further into the river catchment than ranched S. salar, although male ranched S. salar exhibited the greatest cumulative distance moved prior to the spawning period. The management implications of escaped or released ranched S. salar and movement at natural obstacles are discussed. © 2013 The Fisheries Society of the British Isles.

Carcass analog addition enhances juvenile Atlantic salmon (Salmo salar) growth and condition

USGS Publications Warehouse

Guyette, Margaret Q.; Loftin, Cynthia S.; Zydlewski, Joseph D.

2013-01-01

Our study used historic marine-derived nutrient (MDN) delivery timing to simulate potential effects of restored connectivity on juvenile Atlantic salmon (ATS; Salmo salar) growth and condition. Four headwater streams were stocked with ATS young of the year (YOY) and received carcass analog additions (0.10 kg·m–2 wetted area) in treatment reaches to match the timing of sea lamprey (Petromyzon marinus) spawning. Individual ATS mass was 33%–48% greater and standard length was 9%–15% greater in treatment reaches relative to control reaches for 4 months following nutrient additions. Percent total lipids in YOY ATS were twice as great in treatment reaches 1 month following carcass analog additions and remained elevated in treatment fish for 2 more months. Absolute growth rates, based on otolith microstructure analysis, correlated with water temperature fluctuations in all reaches and were elevated by an average of 0.07 mm·day–1 in treatment reaches for 1 month following carcass analog additions. Simulated sea lamprey MDNs increased juvenile ATS growth, which, via potential increases in overwinter survival and decreases in smolt age, may contribute to population persistence and ecosystem productivity.

Spatial and temporal variability of macroinvertebrates in spawning and non-spawning habitats during a salmon run in Southeast Alaska.

PubMed

Campbell, Emily Y; Merritt, Richard W; Cummins, Kenneth W; Benbow, M Eric

2012-01-01

Spawning salmon create patches of disturbance through redd digging which can reduce macroinvertebrate abundance and biomass in spawning habitat. We asked whether displaced invertebrates use non-spawning habitats as refugia in streams. Our study explored how the spatial and temporal distribution of macroinvertebrates changed during a pink salmon (Oncorhynchus gorbuscha) spawning run and compared macroinvertebrates in spawning (riffle) and non-spawning (refugia) habitats in an Alaskan stream. Potential refugia included: pools, stream margins and the hyporheic zone, and we also sampled invertebrate drift. We predicted that macroinvertebrates would decline in riffles and increase in drift and refugia habitats during salmon spawning. We observed a reduction in the density, biomass and taxonomic richness of macroinvertebrates in riffles during spawning. There was no change in pool and margin invertebrate communities, except insect biomass declined in pools during the spawning period. Macroinvertebrate density was greater in the hyporheic zone and macroinvertebrate density and richness increased in the drift during spawning. We observed significant invertebrate declines within spawning habitat; however in non-spawning habitat, there were less pronounced changes in invertebrate density and richness. The results observed may be due to spawning-related disturbances, insect phenology, or other variables. We propose that certain in-stream habitats could be important for the persistence of macroinvertebrates during salmon spawning in a Southeast Alaskan stream.

Spatial and Temporal Variability of Macroinvertebrates in Spawning and Non-Spawning Habitats during a Salmon Run in Southeast Alaska

PubMed Central

Campbell, Emily Y.; Merritt, Richard W.; Cummins, Kenneth W.; Benbow, M. Eric

2012-01-01

Spawning salmon create patches of disturbance through redd digging which can reduce macroinvertebrate abundance and biomass in spawning habitat. We asked whether displaced invertebrates use non-spawning habitats as refugia in streams. Our study explored how the spatial and temporal distribution of macroinvertebrates changed during a pink salmon (Oncorhynchus gorbuscha) spawning run and compared macroinvertebrates in spawning (riffle) and non-spawning (refugia) habitats in an Alaskan stream. Potential refugia included: pools, stream margins and the hyporheic zone, and we also sampled invertebrate drift. We predicted that macroinvertebrates would decline in riffles and increase in drift and refugia habitats during salmon spawning. We observed a reduction in the density, biomass and taxonomic richness of macroinvertebrates in riffles during spawning. There was no change in pool and margin invertebrate communities, except insect biomass declined in pools during the spawning period. Macroinvertebrate density was greater in the hyporheic zone and macroinvertebrate density and richness increased in the drift during spawning. We observed significant invertebrate declines within spawning habitat; however in non-spawning habitat, there were less pronounced changes in invertebrate density and richness. The results observed may be due to spawning-related disturbances, insect phenology, or other variables. We propose that certain in-stream habitats could be important for the persistence of macroinvertebrates during salmon spawning in a Southeast Alaskan stream. PMID:22745724

Impact of long-term moderate hypercapnia and elevated temperature on the energy budget of isolated gills of Atlantic cod (Gadus morhua).

PubMed

Kreiss, Cornelia M; Michael, Katharina; Bock, Christian; Lucassen, Magnus; Pörtner, Hans-O

2015-04-01

Effects of severe hypercapnia have been extensively studied in marine fishes, while knowledge on the impacts of moderately elevated CO2 levels and their combination with warming is scarce. Here we investigate ion regulation mechanisms and energy budget in gills from Atlantic cod acclimated long-term to elevated PCO2 levels (2500 μatm) and temperature (18°C). Isolated perfused gill preparations were established to determine gill thermal plasticity during acute exposures (10-22°C) and in vivo costs of Na(+)/K(+)-ATPase activity, protein and RNA synthesis. Maximum enzyme capacities of F1Fo-ATPase, H(+)-ATPase and Na(+)/K(+)-ATPase were measured in vitro in crude gill homogenates. After whole animal acclimation to elevated PCO2 and/or warming, branchial oxygen consumption responded more strongly to acute temperature change. The fractions of gill respiration allocated to protein and RNA synthesis remained unchanged. In gills of fish CO2-exposed at both temperatures, energy turnover associated with Na(+)/K(+)-ATPase activity was reduced by 30% below rates of control fish. This contrasted in vitro capacities of Na(+)/K(+)-ATPase, which remained unchanged under elevated CO2 at 10°C, and earlier studies which had found a strong upregulation under severe hypercapnia. F1Fo-ATPase capacities increased in hypercapnic gills at both temperatures, whereas Na(+)/K(+)ATPase and H(+)-ATPase capacities only increased in response to elevated CO2 and warming indicating the absence of thermal compensation under CO2. We conclude that in vivo ion regulatory energy demand is lowered under moderately elevated CO2 levels despite the stronger thermal response of total gill respiration and the upregulation of F1Fo-ATPase. This effect is maintained at elevated temperature. Copyright © 2014 Elsevier Inc. All rights reserved.

The Two-Column Aerosol Project: Phase I-Overview and impact of elevated aerosol layers on aerosol optical depth

DOE PAGES

Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; ...

2016-01-08

The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facilitymore » (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had aerosol layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). In addition, these layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. Lastly, while there was a great deal of spatial and day-to-day variability in the aerosol chemical composition and optical properties, no systematic differences between the two columns were observed.« less

Column and Near-surface Aerosol Properties during TCAP: Temporal Changes in a Coastal Region

NASA Astrophysics Data System (ADS)

Kassianov, E.; Barnard, J.; Pekour, M. S.; Berg, L. K.; Shilling, J. E.; Fast, J. D.; Michalsky, J. J.; Lantz, K. O.; Hodges, G.

2013-12-01

An important problem facing climate-related studies is to separate the impacts of naturally occurring and anthropogenic aerosol. This problem is even more challenging in coastal regions located downwind of large metropolitan areas. Cape Cod situated on the easternmost portion of Massachusetts (along the east coast of the United States) is an example of one of these regions. The Two-Column Aerosol Project (TCAP; http://campaign.arm.gov/tcap/) was designed to study the evolution of optical, microphysical and chemical properties of both marine aerosol and aerosol transported from North America to the Atlantic as well as their impact on the radiation energy budget. The TCAP has been recently conducted (2012-2013) on Cape Cod with support from the U.S. Department of Energy's (DOE's) Atmospheric Radiation Measurement (ARM) Program (http://www.arm.gov/). During the TCAP, the ground-based ARM Mobile Facility (AMF) was deployed on Cape Cod. The AMF site (at 41.87°N; 70.28°W) was equipped with numerous instruments for sampling aerosol, cloud and radiative properties, including a Multi-Filter Rotating Shadowband Radiometer (MFRSR), a Scanning Mobility Particle Sizer (SMPS), an Aerodynamic Particle Sizer (APS), a three-wavelength nephelometer, and suite of instruments to measure the aerosol chemical composition. In this study we present an analysis of diurnal and day-to-day variability of the column and near-surface aerosol properties obtained from remote sensing (MFRSR data) and in situ measurements (SMPS, APS, nephelometer, chemical composition), respectively. The importance of this variability to direct aerosol radiative forcing at different time scales and its relation to the long-range transport will be discussed. Some regional model results will also be presented.

Migration and spawning of female surubim (Pseudoplatystoma corruscans, Pimelodidae) in the São Francisco river, Brazil

USGS Publications Warehouse

Godinho, Alexandre L.; Kynard, Boyd; Godinho, Hugo P.

2007-01-01

Surubim, Pseudoplatystoma corruscans, is the most valuable commercial and recreational fish in the São Francisco River, but little is known about adult migration and spawning. Movements of 24 females (9.5–29.0 kg), which were radio-tagged just downstream of Três Marias Dam (TMD) at river kilometer 2,109 and at Pirapora Rapids (PR) 129 km downstream of TMD, suggest the following conceptual model of adult female migration and spawning. The tagged surubims used only 274 km of the main stem downstream of TMD and two tributaries, the Velhas and Abaeté rivers. Migration style was dualistic with non-migratory (resident) and migratory fish. Pre-spawning females swam at ground speeds of up to 31 km day-1 in late September–December to pre-spawning staging sites located 0–11 km from the spawning ground. In the spawning season (November–March), pre-spawning females migrated back and forth from nearby pre-spawning staging sites to PR for short visits to spawn, mostly during floods. Multiple visits to the spawning site suggest surubim is a multiple spawner. Most post-spawning surubims left the spawning ground to forage elsewhere, but some stayed at the spawning site until the next spawning season. Post-spawning migrants swam up or downstream at ground speeds up to 29 km day-1 during January–March. Construction of proposed dams in the main stem and tributaries downstream of TMD will greatly reduce surubim abundance by blocking migrations and changing the river into reservoirs that eliminate riverine spawning and non-spawning habitats, and possibly, cause extirpation of populations.

Evaluation of methods for identifying spawning sites and habitat selection for alosines

USGS Publications Warehouse

Harris, Julianne E.; Hightower, Joseph E.

2010-01-01

Characterization of riverine spawning habitat is important for the management and restoration of anadromous alosines. We examined the relative effectiveness of oblique plankton tows and spawning pads for collecting the eggs of American shad Alosa sapidissima, hickory shad A. mediocris, and “river herring” (a collective term for alewife A. pseudoharengus and blueback herring A. aestivalis) in the Roanoke River, North Carolina. Relatively nonadhesive American shad eggs were only collected by plankton tows, whereas semiadhesive hickory shad and river herring eggs were collected by both methods. Compared with spawning pads, oblique plankton tows had higher probabilities of collecting eggs and led to the identification of longer spawning periods. In assumed spawning areas, twice-weekly plankton sampling for 15 min throughout the spawning season had a 95% or greater probability of collecting at least one egg for all alosines; however, the probabilities were lower in areas with more limited spawning. Comparisons of plankton tows, spawning pads, and two other methods of identifying spawning habitat (direct observation of spawning and examination of female histology) suggested differences in effectiveness and efficiency. Riverwide information on spawning sites and timing for all alosines is most efficiently obtained by plankton sampling. Spawning pads and direct observations of spawning are the best ways to determine microhabitat selectivity for appropriate species, especially when spawning sites have previously been identified. Histological examination can help determine primary spawning sites but is most useful when information on reproductive biology and spawning periodicity is also desired. The target species, riverine habitat conditions, and research goals should be considered when selecting methods with which to evaluate alosine spawning habitat.

RNA-Seq analysis of transcriptome responses in Atlantic cod (Gadus morhua) precision-cut liver slices exposed to benzo[a]pyrene and 17α-ethynylestradiol.

PubMed

Yadetie, Fekadu; Zhang, Xiaokang; Hanna, Eileen Marie; Aranguren-Abadía, Libe; Eide, Marta; Blaser, Nello; Brun, Morten; Jonassen, Inge; Goksøyr, Anders; Karlsen, Odd André

2018-06-07

Polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) that activate the aryl hydrocarbon receptor (Ahr) pathway, and endocrine disruptors acting through the estrogen receptor pathway are among environmental pollutants of major concern. In this work, we exposed Atlantic cod (Gadus morhua) precision-cut liver slices (PCLS) to BaP (10 nM and 1000 nM), ethynylestradiol (EE2) (10 nM and 1000 nM), and equimolar mixtures of BaP and EE2 (10 nM and 1000 nM) for 48 h, and performed RNA-Seq based transcriptome mapping followed by systematic bioinformatics analyses. Our gene expression analysis showed that several genes were differentially expressed in response to BaP and EE2 treatments in PCLS. Strong up-regulation of genes coding for the cytochrome P450 1a (Cyp1a) enzyme and the Ahr repressor (Ahrrb) was observed in BaP treated PCLS. EE2 treatment of liver slices strongly up-regulated genes coding for precursors of vitellogenin (Vtg) and eggshell zona pellucida (Zp) proteins. As expected, pathway enrichment and network analysis showed that the Ahr and estrogen receptor pathways are among the top affected by BaP and EE2 treatments, respectively. Interestingly, two genes coding for fibroblast growth factor 3 (Fgf3) and fibroblast growth factor 4 (Fgf4) were up-regulated by EE2 in this study. To our knowledge, the fgf3 and fgf4 genes have not previously been described in relation to estrogen signaling in fish liver, and these results suggest the modulation of the FGF signaling pathway by estrogens in fish. The signature expression profiles of top differentially expressed genes in response to the single compound (BaP or EE2) treatment were generally maintained in the expression responses to the equimolar binary mixtures. However, in the mixture-treated groups, BaP appeared to have anti-estrogenic effects as observed by lower number of differentially expressed putative EE2 responsive genes. Our in-depth quantitative analysis of changes in liver transcriptome in response to BaP and EE2, using PCLS tissue culture provides further mechanistic insights into effects of the compounds. Moreover, the analyses demonstrate the usefulness of PCLS in cod for omics experiments. Copyright © 2018 Elsevier B.V. All rights reserved.

Artificial reproduction of two different spawn-forms of the chub.

PubMed

Krejszeff, Sławomir; Targońska, Katarzyna; Zarski, Daniel; Kucharczyk, Dariusz

2010-03-01

The aim of this study was to compare, under controlled conditions, reproduction results of cultured and wild stock of the chub. Wild fish spawned only once a season whereas the cultured stock spawned at least two times. In the multiple-spawn stock, fewer fish spawned and the weight of produced oocytes was reduced compared to the single-spawn stock. Larvae obtained from the multi-spawn forms were smaller than those of the single-spawn stock. The occurrence of one species with two forms of spawning performance in the same area makes it difficult to develop an efficient method for controlling the reproduction.

Summer spawning of Porites lutea from north-western Australia

NASA Astrophysics Data System (ADS)

Stoddart, C. W.; Stoddart, J. A.; Blakeway, D. R.

2012-09-01

Most coral species off Australia's west coast spawn in the austral autumn (March-April), with a few species also spawning in the southern spring or early summer (November-December). This is the reverse timing to spawning recorded off Australia's east coast. Porites lutea, a gonochoric broadcast spawner that is common on Australia's west coast, is shown here to spawn in the months of November or December, as it does on Australia's east coast. Spawning occurred between 2 and 5 nights after full moon, with the majority of spawning activity on night 3. Gametes developed over three to four months with rapid development in the last two weeks before spawning. Zooxanthellae were typically observed in mature oocytes, only a week before spawning so their presence may provide a useful indicator of imminent spawning.

Tornado Strikes Southern Maryland

NASA Technical Reports Server (NTRS)

2002-01-01

Evening light catches the tops of towering thunderheads over the Mid-Atlantic states on April 28, 2002. The powerful storms spawned several tornados, one of which was classified as an F4 tornado. The powerful tornado touched down in the southern Maryland town of La Plata, destroying most of the historic downtown. The twister-one of the strongest ever to hit the state-beat a 24-mile swath running west to east through the state and claimed at least three lives. The image above was taken by the Geostationary Operational Environmental Satellite (GOES) at 7:15 PM Eastern Daylight Savings Time. A large version of the animation shows more detail. (5.9 MB Quicktime) Image courtesy National Oceanic and Atmospheric Administration (NOAA) and the GOES Project Science Office. Animation by Robert Simmon, NASA GSFC.

Habitat Suitability Index Models and Instream Flow Suitability Curves: American shad

USGS Publications Warehouse

Stier, David J.; Crance, Johnie H.

1985-01-01

INTRODUCTION The American shad, an anadromous species, is the largest member of the herring family (Clupeidae) and is native to North America (Talbot and Sykes 1958; Hildebrand 1963; Walburg and Nichols 1967). Historically, the commercial fishery for American shad on the Atlantic coast was widespread and intense; in 1896 the estimated catch was 22.7 million kg (50 million lb). By 1960, however, the estimated catch had dropped to slightly more than 3.6 million kg (8 million lb), according to Walburg and Nichols (1967). Pollution, overfishing, and dams constructed across streams that prevent shad from reaching their spawning grounds have caused partial or total depletion of stocks (Hildebrand 1963). Several programs aimed at restoring American shad to their former range have been initiated by Federal and State agencies.

Evidence for a regulatory loop between cholecystokinin (CCK) and tryptic enzyme activity in Atlantic cod larvae (Gadus morhua).

PubMed

Tillner, Robert; Rønnestad, Ivar; Harboe, Torstein; Ueberschär, Bernd

2013-11-01

In order to maximize protein digestion, the release of enzymes into the gut lumen is closely controlled by a regulatory loop. Cholecystokinin (CCK) is among the enteric hormones that play a key role in the control of digestive enzyme secretion, but its role in first-feeding larvae is still unclear and may differ between species. However, in all marine fish larvae that have not developed a stomach by first-feeding, trypsin is the most important proteolytic enzyme. In order to examine the regulation and feedback mechanisms in the gut of larval cod, we therefore studied the interactions between cholecystokinin and tryptic enzyme activity following the administration of solutions containing test substances directly into the gut. We tube-fed a single dose of physiological saline solution containing either CCK, CCK antagonist, trypsin inhibitor, phytohemagglutinin (PHA; a possible trigger for the digestive response) or physiological saline alone, while a further control group was left untreated. We then followed the response in CCK and tryptic enzyme activity for 0.5-8h after the administration. We performed the experiment on larvae at 26day post first-feeding, which is before the stomach has evolved and the size of the larvae allows easier handling. Individual larvae were analyzed for CCK and tryptic enzyme activity using radioimmunoassay and fluorimetric techniques respectively. Both factors varied over time in the untreated control group, possibly due to an endogenous daily rhythm. The higher CCK levels at 4h and 8h in the saline-injected group may be caused by reflexes initiated by distension of the gut. An increase in tryptic enzyme activity after injection of CCK supports the hypothesis that this hormone plays a part in the release of pancreatic enzymes in larval cod at this developmental stage. However, administration of a CCK antagonist and a trypsin inhibitor did not reveal conclusive results, probably due to the relatively low concentrations used. The response in tryptic activity in the PHA group was similar to the administration of CCK, pointing towards a stimulatory effect of PHA on the proteolytic enzyme capacity of cod larvae. © 2013.

Spawn in two deep-sea volute gastropods (Neogastropoda: Volutidae) from southwestern Atlantic waters

NASA Astrophysics Data System (ADS)

Penchaszadeh, Pablo E.; Teso, Valeria; Pastorino, Guido

2017-12-01

The gastropods Odontocymbiola pescalia and Provocator corderoi and their egg capsules were collected by the R/V Puerto Deseado from the Mar del Plata Submarine Canyon ( 37°53‧S, at depths of 291-1404 m) and from Burdwood Bank ( 54°27‧S, 128-785 m). Odontocymbiola pescalia egg capsules measured 15.67 ± 3.38 mm in diameter. They were subspherical in shape with an external calcareous layer. Each egg capsule contained 3-5 embryos and white material as extra embryonic food. Embryos grew to a size of up to 9.3 ± 1.1 mm in mean shell length before hatching as crawling juveniles. The spawn of P. corderoi consisted of a single dome shaped egg capsule of 14.17 ± 1.5 mm in diameter, attached to hard substrata by a basal membrane with a rounded outline. A curved semilunar furrow (seam) on one side of the capsules was always present. The number of embryos per capsule was 2-6. Embryos hatched as crawling juveniles with a shell length of 5.9 ± 0.6 mm. The size and number of whorls in the hatchling shell suggested a slow rate of development, akin to many other deep-sea invertebrates. The egg capsules and reproductive development strategies of both species were compared with those from other congeneric representatives.

Type of carbohydrate in feed affects the expression of small leucine-rich proteoglycans (SLRPs), glycosaminoglycans (GAGs) and interleukins in skeletal muscle of Atlantic cod (Gadus morhua L.).

PubMed

Tingbø, M G; Pedersen, M E; Grøndahl, F; Kolset, S O; Veiseth-Kent, E; Enersen, G; Hannesson, K O

2012-09-01

Aquaculture requires feed that ensures rapid growth and healthy fish. Higher inclusion of plant ingredients is desirable, as marine resources are limited. In this study we investigated the effects of higher starch inclusion in feed on muscular extracellular matrix and interleukin expression in farmed cod. Starch was replaced by complex fibers in the low-starch diet to keep total carbohydrate inclusion similar. Blood glucose and fructosamine levels were elevated in the high-starch group. The group fed a high-starch diet showed up-regulation on mRNA level of proteoglycans biglycan and decorin. ELISA confirmed the real-time PCR results on protein level for biglycan and also showed increase of lumican. For decorin the protein levels were decreased in the high-starch group, in contrast to real-time PCR results. Disaccharide analyses using HPLC showed reduction of glycosaminoglycans. Further, there was up-regulation of interleukin-1β and -10 on mRNA level in muscle. This study shows that the muscular extracellular matrix composition is affected by diet, and that a high-starch diet results in increased expression of pro-inflammatory genes similar to diabetes in humans. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cod Gadus morhua and climate change: processes, productivity and prediction.

PubMed

Brander, K M

2010-11-01

Environmental factors act on individual fishes directly and indirectly. The direct effects on rates and behaviour can be studied experimentally and in the field, particularly with the advent of ever smarter tags for tracking fishes and their environment. Indirect effects due to changes in food, predators, parasites and diseases are much more difficult to estimate and predict. Climate can affect all life-history stages through direct and indirect processes and although the consequences in terms of growth, survival and reproductive output can be monitored, it is often difficult to determine the causes. Investigation of cod Gadus morhua populations across the whole North Atlantic Ocean has shown large-scale patterns of change in productivity due to lower individual growth and condition, caused by large-scale climate forcing. If a population is being heavily exploited then a drop in productivity can push it into decline unless the level of fishing is reduced: the idea of a stable carrying capacity is a dangerous myth. Overexploitation can be avoided by keeping fishing mortality low and by monitoring and responding rapidly to changes in productivity. There are signs that this lesson has been learned and that G. morhua will continue to be a mainstay of the human diet. © 2010 The Author. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

Variability of spawning time (lunar day) in Acropora versus merulinid corals: a 7-yr record of in situ coral spawning in Taiwan

NASA Astrophysics Data System (ADS)

Lin, Che-Hung; Nozawa, Yoko

2017-12-01

Despite the global accumulation of coral spawning records over the past three decades, information on inter-annual variation in spawning time is still insufficient, resulting in difficulty in predicting coral spawning time. Here, we present new information on in situ spawning times of scleractinian corals at Lyudao, Taiwan, covering their inter-annual variations over a 7-yr period (2010-2016). Spawning of 42 species from 16 genera in eight families was recorded. The majority were hermaphroditic spawners (38 of 42 species), and their spawning occurred 2-4 h after sunset on 1-11 d after the full moon (AFM), mostly in April and May. There were two distinct patterns in the two dominant taxa, the genus Acropora (14 species) and the family Merulinidae (18 species in eight genera). The annual spawning of Acropora corals mostly occurred on a single night in May with high inter-annual variation of spawning (lunar) days between 1 and 11 d AFM. In contrast, the annual spawning of merulinid corals commonly occurred over 2-3 consecutive nights in two consecutive months, April and May, with the specific range of spawning days around the last quarter moon (between 5 and 8 d AFM). The distinct spawning patterns of these taxa were also documented at Okinawa and Kochi, Japan, where similar long-term monitoring of in situ coral spawning has been conducted. This variability in spawning days implies different regulatory mechanisms of synchronous spawning where Acropora corals might be more sensitive to exogenous environmental factors (hourglass mechanism), compared to merulinid corals, which may rely more on endogenous biological rhythms (oscillator mechanism).

Effects of lake surface elevation on shoreline-spawning Lost River Suckers

USGS Publications Warehouse

Burdick, Summer M.; Hewitt, David A.; Rasmussen, J.E.; Hayes, Brian; Janney, Eric; Harris, Alta C.

2015-01-01

We analyzed remote detection data from PIT-tagged Lost River Suckers Deltistes luxatus at four shoreline spawning areas in Upper Klamath Lake, Oregon, to determine whether spawning of this endangered species was affected by low water levels. Our investigation was motivated by the observation that the surface elevation of the lake during the 2010 spawning season was the lowest in 38 years. Irrigation withdrawals in 2009 that were not replenished by subsequent winter-spring inflows caused a reduction in available shoreline spawning habitat in 2010. We compared metrics of skipped spawning, movement among spawning areas, and spawning duration across 8 years (2006-2013) that had contrasting spring water levels. Some aspects of sucker spawning were similar in all years, including few individuals straying from the shoreline areas to spawning locations in lake tributaries and consistent effects of increasing water temperatures on the accumulation of fish at the spawning areas. During the extreme low water year of 2010, 14% fewer female and 8% fewer male suckers joined the shoreline spawning aggregation than in the other years. Both males and females visited fewer spawning areas within Upper Klamath Lake in 2010 than in other years, and the median duration at spawning areas in 2010 was at least 36% shorter for females and 20% shorter for males relative to other years. Given the imperiled status of the species and the declining abundance of the population in Upper Klamath Lake, any reduction in spawning success and egg production could negatively impact recovery efforts. Our results indicate that lake surface elevations above 1,262.3-1,262.5 m would be unlikely to limit the number of spawning fish and overall egg production.

Environmental and biological characteristics of Atlantic bluefin tuna and albacore spawning habitats based on their egg distributions

NASA Astrophysics Data System (ADS)

Reglero, Patricia; Santos, Maria; Balbín, Rosa; Laíz-Carrión, Raul; Alvarez-Berastegui, Diego; Ciannelli, Lorenzo; Jiménez, Elisa; Alemany, Francisco

2017-06-01

Tuna spawning habitats are traditionally characterized using data sets of larvae or gonads from mature adults and concurrent environmental variables. Data on egg distributions have never previously been used since molecular analyses are mandatory to identify tuna eggs to species level. However, in this study we use molecularly derived egg distribution data, in addition to larval data, to characterize hydrographic and biological drivers of the spatial distribution of eggs and larvae of bluefin Thunnus thynnus and albacore tuna Thunnus alalunga in the Balearic Sea, a main spawning area of these species in the Mediterranean. The effects of the hydrography, characterized by salinity, temperature and geostrophic velocity, on the spatial distributions of the eggs and larvae are investigated. Three biological variables are used to describe the productivity in the area: chlorophyll a in the mixed layer, chlorophyll a in the deep chlorophyll maximum and mesozooplankton biomass in the mixed layer. Our results point to the importance of salinity fronts and temperatures above a minimum threshold in shaping the egg and larval distribution of both species. The spatial distribution of the biotic variables was very scattered, and they did not emerge as significant variables in the presence-absence models. However, they became significant when modeling egg and larval abundances. The lack of correlation between the three biotic variables challenges the use of chlorophyll a to describe trophic scenarios for the larvae and suggests that the spatial distribution of resources is not persistent in time. The different patterns in relation to biotic variables across species and stages found in this and other studies indicate a still elusive understanding of the link between trophic levels involving tuna early larval stages. Our ability to improve short-term forecasting and long-term predictions of climate effects on the egg and larval distributions is discussed based on the consistency of the environmentally driven spatial patterns for the two species.

What was natural in the coastal oceans?

PubMed Central

Jackson, Jeremy B. C.

2001-01-01

Humans transformed Western Atlantic coastal marine ecosystems before modern ecological investigations began. Paleoecological, archeological, and historical reconstructions demonstrate incredible losses of large vertebrates and oysters from the entire Atlantic coast. Untold millions of large fishes, sharks, sea turtles, and manatees were removed from the Caribbean in the 17th to 19th centuries. Recent collapses of reef corals and seagrasses are due ultimately to losses of these large consumers as much as to more recent changes in climate, eutrophication, or outbreaks of disease. Overfishing in the 19th century reduced vast beds of oysters in Chesapeake Bay and other estuaries to a few percent of pristine abundances and promoted eutrophication. Mechanized harvesting of bottom fishes like cod set off a series of trophic cascades that eliminated kelp forests and then brought them back again as fishers fished their way down food webs to small invertebrates. Lastly, but most pervasively, mechanized harvesting of the entire continental shelf decimated large, long-lived fishes and destroyed three-dimensional habitats built up by sessile corals, bryozoans, and sponges. The universal pattern of losses demonstrates that no coastal ecosystem is pristine and few wild fisheries are sustainable along the entire Western Atlantic coast. Reconstructions of ecosystems lost only a century or two ago demonstrate attainable goals of establishing large and effective marine reserves if society is willing to pay the costs. Historical reconstructions provide a new scientific framework for manipulative experiments at the ecosystem scale to explore the feasibility and benefits of protection of our living coastal resources. PMID:11344287

Identification of lake trout Salvelinus namaycush spawning habitat in northern Lake Huron using high-resolution satellite imagery

USGS Publications Warehouse

Grimm, Amanda G.; Brooks, Colin N.; Binder, Thomas R.; Riley, Stephen C.; Farha, Steve A.; Shuchman, Robert A.; Krueger, Charles C.

2016-01-01

The availability and quality of spawning habitat may limit lake trout recovery in the Great Lakes, but little is known about the location and characteristics of current spawning habitats. Current methods used to identify lake trout spawning locations are time- and labor-intensive and spatially limited. Due to the observation that some lake trout spawning sites are relatively clean of overlaying algae compared to areas not used for spawning, we suspected that spawning sites could be identified using satellite imagery. Satellite imagery collected just before and after the spawning season in 2013 was used to assess whether lake trout spawning habitat could be identified based on its spectral characteristics. Results indicated that Pléiades high-resolution multispectral satellite imagery can be successfully used to estimate algal coverage of substrates and temporal changes in algal coverage, and that models developed from processed imagery can be used to identify potential lake trout spawning sites based on comparison of sites where lake trout eggs were and were not observed after spawning. Satellite imagery is a potential new tool for identifying lake trout spawning habitat at large scales in shallow nearshore areas of the Great Lakes.

Stochastic dynamic programming illuminates the link between environment, physiology, and evolution.

PubMed

Mangel, Marc

2015-05-01

I describe how stochastic dynamic programming (SDP), a method for stochastic optimization that evolved from the work of Hamilton and Jacobi on variational problems, allows us to connect the physiological state of organisms, the environment in which they live, and how evolution by natural selection acts on trade-offs that all organisms face. I first derive the two canonical equations of SDP. These are valuable because although they apply to no system in particular, they share commonalities with many systems (as do frictionless springs). After that, I show how we used SDP in insect behavioral ecology. I describe the puzzles that needed to be solved, the SDP equations we used to solve the puzzles, and the experiments that we used to test the predictions of the models. I then briefly describe two other applications of SDP in biology: first, understanding the developmental pathways followed by steelhead trout in California and second skipped spawning by Norwegian cod. In both cases, modeling and empirical work were closely connected. I close with lessons learned and advice for the young mathematical biologists.

Prevalence of infectious salmon anaemia virus (ISAV) in wild salmonids in western Norway.

PubMed

Plarre, H; Devold, M; Snow, M; Nylund, A

2005-08-09

Studies of infectious salmon anaemia virus (ISAV), an important pathogen of farmed salmon in Norway, Scotland, the Faeroe Islands, Ireland, Canada, the USA and Chile, suggest that natural reservoirs for this virus can be found on both sides of the North Atlantic. Based on existing information about ISAV it is believed to be maintained in wild populations of trout and salmon in Europe. It has further been suggested that ISAV is transmitted between wild hosts, mainly during their freshwater spawning phase in rivers, and that wild salmonids, mainly trout, are possible carriers of benign wild-type variants of ISAV. Change in virulence is probably a result of deletions of amino acid segments from the highly polymorphic region (HPR) of benign wild-type isolates after transmission to farmed salmon. Hence, it has been suggested that the frequency of new outbreaks of ISA in farmed salmon could partly reflect natural variation in the prevalence of ISAV in wild populations of salmonids. The aims of the present study were to screen for ISAV in wild salmonids during spawning in rivers and to determine the pathogenicity of resultant isolates from wild fish. Tissues from wild salmonids were screened by RT-PCR and real-time PCR. The prevalence of ISAV in wild trout Salmo trutta varied from 62 to 100% between tested rivers in 2001. The prevalence dropped in 2002, ranging from 13 to 36% in the same rivers and to only 6% in 2003. All ISAV were nonpathogenic when injected into disease-free Atlantic salmon, but were capable of propagation, as indicated by subsequent viral recovery. However, non-pathogenic ISAV has also been found in farmed salmon, where a prevalence as high as 60% has been registered, but with no mortalities occurring. Based on the results of the present and other studies, it must be concluded that vital information about the importance of wild and man-made reservoirs for the emergence of ISA in salmon farming is still lacking. This information can only be gained by further screening of possible reservoirs, combined with the development of a molecular tool for typing virulence and the geographical origin of the virus isolates.

Physiological-based modelling of marine fish early life stages provides process knowledge on climate impacts

NASA Astrophysics Data System (ADS)

Peck, M. A.

2016-02-01

Gaining a cause-and-effect understanding of climate-driven changes in marine fish populations at appropriate spatial scales is important for providing robust advice for ecosystem-based fisheries management. Coupling long-term, retrospective analyses and 3-d biophysical, individual-based models (IBMs) shows great potential to reveal mechanism underlying historical changes and to project future changes in marine fishes. IBMs created for marine fish early life stages integrate organismal-level physiological responses and climate-driven changes in marine habitats (from ocean physics to lower trophic level productivity) to test and reveal processes affecting marine fish recruitment. Case studies are provided for hindcasts and future (A1 and B2 projection) simulations performed on some of the most ecologically- and commercially-important pelagic and demersal fishes in the North Sea including European anchovy, Atlantic herring, European sprat and Atlantic cod. We discuss the utility of coupling biophysical IBMs to size-spectrum models to better project indirect (trophodynamic) pathways of climate influence on the early life stages of these and other fishes. Opportunities and challenges are discussed regarding the ability of these physiological-based tools to capture climate-driven changes in living marine resources and food web dynamics of shelf seas.

Genetic variation and geographic differentiation in the marine triclad Bdelloura candida (Platyhelminthes, Tricladida, Maricola), ectocommensal on the American horseshoe crab Limulus polyphemus.

PubMed

Riesgo, Ana; Burke, Emily A; Laumer, Christopher; Giribet, Gonzalo

2017-01-01

Bdelloura candida (Platyhelminthes, Tricladida, Maricola) is an ectocommensal symbiont on the American horseshoe crab Limulus polyphemus , living on the book gills and appendages, where it spends its entire life. Given its limited dispersal capabilities and its inability to live outside of the host, we hypothesized a genetic structure that parallels that of its host. We obtained 84 planarian individuals from 19 horseshoe crabs collected from 10 sites from Massachusetts to Florida. We amplified the mitochondrial 16S rRNA and the nuclear internal transcribed spacer 2 and conducted phylogeographic and population genetic analyses, which show a clear and strong genetic break between the populations in the Atlantic and the Gulf coasts. Among the Atlantic populations, two additional, weaker barriers located along Cape Hatteras and Cape Cod restrict gene flow. Even though previous studies have suggested that the populations of the host may be in decline, those of B. candida remain stable, and some even shows signatures of expansion. Our results indicate that the phylogeography of these marine ectocommensal triclads closely mirrors that of its Limulus host, and highlight the challenges to both host and symbiont to genetically connect populations across their distribution.

Effect of short-term regulated temperature variations on the swimming economy of Atlantic salmon smolts

PubMed Central

Palstra, A. P.

2017-01-01

Abstract Migratory species travelling long distances between habitats to spawn or feed are well adapted to optimize their swimming economy. However, human activities, such as river regulation, represent potential threats to fish migration by changing environmental parameters that will have impact on their metabolism. The main objective of this study was to evaluate the changes in the swimming energetics of a salmonid species, Atlantic salmon (Salmo salar L.), caused by short-term temperature variations that usually result from the operation of hydroelectrical dams. Intermittent flow respirometry in swim tunnels allows to obtain high resolution data on oxygen consumption of swimming fish which can reflect aerobic and anaerobic metabolism. This method was used to compare the metabolic rates of oxygen consumption before, during and after sudden thermal change. Control (no temperature variation) and experimental (temperature variation of approximately 4°C in 1 h) swimming trials were conducted to achieve the following objectives: (i) quantify the variations in oxygen consumption associated with abrupt temperature decrease, and (ii) assess if the tested fish return quickly to initial oxygen consumption rates. Main results revealed that Atlantic salmon smolts show a strong response to sudden temperature variation, significantly reducing the oxygen consumption rate up to a seven-fold change. Fish quickly returned to initial swimming costs shortly after reestablishment of temperature values. Results from this study can be used to evaluate the species-specific effects of the applied operation modes by hydroelectrical dams and to increase the success of conservation and management actions directed to fish species inhabiting regulated rivers. PMID:28480037

Effect of short-term regulated temperature variations on the swimming economy of Atlantic salmon smolts.

PubMed

Alexandre, C M; Palstra, A P

2017-01-01

Migratory species travelling long distances between habitats to spawn or feed are well adapted to optimize their swimming economy. However, human activities, such as river regulation, represent potential threats to fish migration by changing environmental parameters that will have impact on their metabolism. The main objective of this study was to evaluate the changes in the swimming energetics of a salmonid species, Atlantic salmon ( Salmo salar L.), caused by short-term temperature variations that usually result from the operation of hydroelectrical dams. Intermittent flow respirometry in swim tunnels allows to obtain high resolution data on oxygen consumption of swimming fish which can reflect aerobic and anaerobic metabolism. This method was used to compare the metabolic rates of oxygen consumption before, during and after sudden thermal change. Control (no temperature variation) and experimental (temperature variation of approximately 4°C in 1 h) swimming trials were conducted to achieve the following objectives: (i) quantify the variations in oxygen consumption associated with abrupt temperature decrease, and (ii) assess if the tested fish return quickly to initial oxygen consumption rates. Main results revealed that Atlantic salmon smolts show a strong response to sudden temperature variation, significantly reducing the oxygen consumption rate up to a seven-fold change. Fish quickly returned to initial swimming costs shortly after reestablishment of temperature values. Results from this study can be used to evaluate the species-specific effects of the applied operation modes by hydroelectrical dams and to increase the success of conservation and management actions directed to fish species inhabiting regulated rivers.

Electrically-Active Convection in Tropical Easterly Waves and Implications for Tropical Cyclogenesis in the Atlantic and East Pacific

NASA Technical Reports Server (NTRS)

Leppert, Kenneth D., II; Petersen, Walter A.; Cecil, Daniel J.

2012-01-01

In this study, we investigate the characteristics of tropical easterly wave convection and the possible implications of convective structure on tropical cyclogenesis and intensification over the Atlantic Ocean and East Pacific using data from the Tropical Rainfall Measurement Mission Microwave Imager, Precipitation Radar (PR), and Lightning Imaging Sensor as well as infrared (IR) brightness temperature data from the NASA global-merged IR brightness temperature dataset. Easterly waves were partitioned into northerly, southerly, trough, and ridge phases based on the 700-hPa meridional wind from the NCEP-NCAR reanalysis dataset. Waves were subsequently divided according to whether they did or did not develop tropical cyclones (i.e., developing and nondeveloping, respectively), and developing waves were further subdivided according to development location. Finally, composites as a function of wave phase and category were created using the various datasets. Results suggest that the convective characteristics that best distinguish developing from nondeveloping waves vary according to where developing waves spawn tropical cyclones. For waves that developed a cyclone in the Atlantic basin, coverage by IR brightness temperatures .240 K and .210 K provide the best distinction between developing and nondeveloping waves. In contrast, several variables provide a significant distinction between nondeveloping waves and waves that develop cyclones over the East Pacific as these waves near their genesis location including IR threshold coverage, lightning flash rates, and low-level (<4.5 km) PR reflectivity. Results of this study may be used to help develop thresholds to better distinguish developing from nondeveloping waves and serve as another aid for tropical cyclogenesis forecasting.

Life-stage-associated remodelling of lipid metabolism regulation in Atlantic salmon.

PubMed

Gillard, Gareth; Harvey, Thomas N; Gjuvsland, Arne; Jin, Yang; Thomassen, Magny; Lien, Sigbjørn; Leaver, Michael; Torgersen, Jacob S; Hvidsten, Torgeir R; Vik, Jon Olav; Sandve, Simen R

2018-03-01

Atlantic salmon migrates from rivers to sea to feed, grow and develop gonads before returning to spawn in freshwater. The transition to marine habitats is associated with dramatic changes in the environment, including water salinity, exposure to pathogens and shift in dietary lipid availability. Many changes in physiology and metabolism occur across this life-stage transition, but little is known about the molecular nature of these changes. Here, we use a long-term feeding experiment to study transcriptional regulation of lipid metabolism in Atlantic salmon gut and liver in both fresh- and saltwater. We find that lipid metabolism becomes significantly less plastic to differences in dietary lipid composition when salmon transitions to saltwater and experiences increased dietary lipid availability. Expression of genes in liver relating to lipogenesis and lipid transport decreases overall and becomes less responsive to diet, while genes for lipid uptake in gut become more highly expressed. Finally, analyses of evolutionary consequences of the salmonid-specific whole-genome duplication on lipid metabolism reveal several pathways with significantly different (p < .05) duplicate retention or duplicate regulatory conservation. We also find a limited number of cases where the whole-genome duplication has resulted in an increased gene dosage. In conclusion, we find variable and pathway-specific effects of the salmonid genome duplication on lipid metabolism genes. A clear life-stage-associated shift in lipid metabolism regulation is evident, and we hypothesize this to be, at least partly, driven by nondietary factors such as the preparatory remodelling of gene regulation and physiology prior to sea migration. © 2018 John Wiley & Sons Ltd.

Paramyxoviruses of fish: Chapter 17

USGS Publications Warehouse

Meyers, Theodore R.; Batts, William N.; Kibenge, Frederick S. B.; Godoy, Marcos

2016-01-01

The first fish paramyxovirus was isolated from normal adult Chinook salmon returning to a coastal hatchery in Oregon in the fall of 1982. Subsequently, the virus was isolated from other stocks of adult Chinook salmon and one stock of adult coho salmon in California, Oregon, Washington and Alaska, leading to its designation as the Pacific salmon paramyxovirus (PSPV). The slow-growing virus can be isolated from tissues and ovarian fluids of healthy adult fish returning to spawn and apparently causes no clinical signs of disease or mortality. In 1995, a different and widely disseminated paramyxovirus was isolated from farmed Atlantic salmon in Norway and was designated as Atlantic salmon paramyxovirus (ASPV). Although this virus caused no disease or mortality when injected into juvenile Atlantic salmon, ASPV has been associated with proliferative gill inflammation in sea-reared yearling fish; however, additional infectious agents may be involved in the etiology of the condition. Sequence analysis of PSPV and ASPV isolates using the polymerase gene established their placement in the family Paramyxoviridaeand has shown the two viruses to be closely related but sufficiently different from each other and from other known paramyxoviruses to possibly represent new genera within the family. The viruses can be diagnosed by isolation in cell culture with final confirmation by molecular methods. Other paramyxovirus-like agents have been observed or isolated from rainbow trout in Germany, from seabream in Japan associated with epithelial necrosis, from turbot in Spain associated with erythrocytic inclusion bodies and buccal/opercular hemorrhaging and from koi and common carp associated with gill necrosis in the European Union.

Spawning Sites of the Japanese Eel in Relation to Oceanographic Structure and the West Mariana Ridge

PubMed Central

Aoyama, Jun; Watanabe, Shun; Miller, Michael J.; Mochioka, Noritaka; Otake, Tsuguo; Yoshinaga, Tatsuki; Tsukamoto, Katsumi

2014-01-01

The Japanese eel, Anguilla japonica, spawns within the North Equatorial Current that bifurcates into both northward and southward flows in its westward region, so its spawning location and larval transport dynamics seem important for understanding fluctuations in its recruitment to East Asia. Intensive research efforts determined that Japanese eels spawn along the western side of the West Mariana Ridge during new moon periods, where all oceanic life history stages have been collected, including eggs and spawning adults. However, how the eels decide where to form spawning aggregations is unknown because spawning appears to have occurred at various latitudes. A salinity front formed from tropical rainfall was hypothesized to determine the latitude of its spawning locations, but an exact spawning site was only found once by collecting eggs in May 2009. This study reports on the collections of Japanese eel eggs and preleptocephali during three new moon periods in June 2011 and May and June 2012 at locations indicating that the distribution of lower salinity surface water or salinity fronts influence the latitude of spawning sites along the ridge. A distinct salinity front may concentrate spawning south of the front on the western side of the seamount ridge. It was also suggested that eels may spawn at various latitudes within low-salinity water when the salinity fronts appeared unclear. Eel eggs were distributed within the 150–180 m layer near the top of the thermocline, indicating shallow spawning depths. Using these landmarks for latitude (salinity front), longitude (seamount ridge), and depth (top of the thermocline) to guide the formation of spawning aggregations could facilitate finding mates and help synchronize their spawning. PMID:24551155

Multispecies spawning sites for fishes on a low-latitude coral reef: spatial and temporal patterns.

PubMed

Claydon, J A B; McCormick, M I; Jones, G P

2014-04-01

Spawning sites used by one or more species were located by intensively searching nearshore coral reefs of Kimbe Bay (New Britain, Papua New Guinea). Once identified, the spawning sites were surveyed repeatedly within fixed 5 m radius circular areas, for  > 2000 h of observations ranging from before dawn to after dusk spanning 190 days between July 2001 and May 2004. A total of 38 spawning sites were identified on the seven study reefs distributed at an average of one site every 60 m of reef edge. Pelagic spawning was observed in 41 fish species from six families. On three intensively studied reefs, all 17 spawning sites identified were used by at least three species, with a maximum of 30 different species observed spawning at a single site. Spawning was observed during every month of the study, on all days of the lunar month, at all states of the tide and at most hours of the day studied. Nevertheless, the majority of species were observed spawning on proportionately more days from December to April, on more days around the new moon and in association with higher tides. The strongest temporal association, however, was with species-specific diel spawning times spanning < 3 h for most species. While dawn spawning, afternoon spawning and dusk spawning species were differentiated, the time of spawning for the striated surgeonfish Ctenochaetus striatus also differed significantly among sites. The large number of species spawning at the same restricted locations during predictable times suggests that these sites are extremely important on this low-latitude coral reef. © 2014 The Fisheries Society of the British Isles.

Spawning sites of the Japanese eel in relation to oceanographic structure and the West Mariana Ridge.

PubMed

Aoyama, Jun; Watanabe, Shun; Miller, Michael J; Mochioka, Noritaka; Otake, Tsuguo; Yoshinaga, Tatsuki; Tsukamoto, Katsumi

2014-01-01

The Japanese eel, Anguilla japonica, spawns within the North Equatorial Current that bifurcates into both northward and southward flows in its westward region, so its spawning location and larval transport dynamics seem important for understanding fluctuations in its recruitment to East Asia. Intensive research efforts determined that Japanese eels spawn along the western side of the West Mariana Ridge during new moon periods, where all oceanic life history stages have been collected, including eggs and spawning adults. However, how the eels decide where to form spawning aggregations is unknown because spawning appears to have occurred at various latitudes. A salinity front formed from tropical rainfall was hypothesized to determine the latitude of its spawning locations, but an exact spawning site was only found once by collecting eggs in May 2009. This study reports on the collections of Japanese eel eggs and preleptocephali during three new moon periods in June 2011 and May and June 2012 at locations indicating that the distribution of lower salinity surface water or salinity fronts influence the latitude of spawning sites along the ridge. A distinct salinity front may concentrate spawning south of the front on the western side of the seamount ridge. It was also suggested that eels may spawn at various latitudes within low-salinity water when the salinity fronts appeared unclear. Eel eggs were distributed within the 150-180 m layer near the top of the thermocline, indicating shallow spawning depths. Using these landmarks for latitude (salinity front), longitude (seamount ridge), and depth (top of the thermocline) to guide the formation of spawning aggregations could facilitate finding mates and help synchronize their spawning.

Annual variation in the timing of coral spawning in a high-latitude environment: influence of temperature.

PubMed

Nozawa, Yoko

2012-06-01

This study was conducted at a high-latitude location (32°N; Kochi, Japan), where annual seawater temperatures show large fluctuations due to the meandering of the Kuroshio Current, providing a unique opportunity to examine the influence of temperature on coral reproduction. Annual spawning of individual colonies of four reef coral species-two Acropora species (Acropora hyacinthus and A. japonica) and two faviid species (Favites pentagona and Platygyra contorta)-was monitored in situ for 4 years in 2006-2009. The spawning of the four species always occurred around the last quarter moon in the local summer, July or August, irrespective of high annual variations in seawater temperatures (from 23.7 to 29.5 °C) and weather during the spawning period. However, the exact timing of spawning during the spawning period varied among the years and was correlated with the cumulative seawater temperature during the late period of gametogenesis (0-3 months before spawning). When seawater temperatures were higher, spawning occurred in the earlier spawning month (July) and vice versa, except in A. hyacinthus, which always spawned in July. In the case of the two Acropora species, higher (lower) temperatures led to spawning earlier (later) in the lunar cycle. Seawater temperature may have an influence on gametogenesis, causing the shift in spawning timing.

Spawning site selection and contingent behavior in Common Snook, Centropomus undecimalis.

PubMed

Lowerre-Barbieri, Susan; Villegas-Ríos, David; Walters, Sarah; Bickford, Joel; Cooper, Wade; Muller, Robert; Trotter, Alexis

2014-01-01

Reproductive behavior affects spatial population structure and our ability to manage for sustainability in marine and diadromous fishes. In this study, we used fishery independent capture-based sampling to evaluate where Common Snook occurred in Tampa Bay and if it changed with spawning season, and passive acoustic telemetry to assess fine scale behavior at an inlet spawning site (2007-2009). Snook concentrated in three areas during the spawning season only one of which fell within the expected spawning habitat. Although in lower numbers, they remained in these areas throughout the winter months. Acoustically-tagged snook (n = 31) showed two seasonal patterns at the spawning site: Most fish occurred during the spawning season but several fish displayed more extended residency, supporting the capture-based findings that Common Snook exhibit facultative catadromy. Spawning site selection for iteroparous, multiple-batch spawning fishes occurs at the lifetime, annual, or intra-annual temporal scales. In this study we show colonization of a new spawning site, indicating that lifetime spawning site fidelity of Common Snook is not fixed at this fine spatial scale. However, individuals did exhibit annual and intra-seasonal spawning site fidelity to this new site over the three years studied. The number of fish at the spawning site increased in June and July (peak spawning months) and on new and full lunar phases indicating within population variability in spawning and movement patterns. Intra-seasonal patterns of detection also differed significantly with sex. Common Snook exhibited divergent migration tactics and habitat use at the annual and estuarine scales, with contingents using different overwintering habitat. Migration tactics also varied at the spawning site at the intra-seasonal scale and with sex. These results have important implications for understanding how reproductive behavior affects spatio-temporal patterns of fish abundance and their resilience to disturbance events and fishing pressure.

Coral mass spawning predicted by rapid seasonal rise in ocean temperature

PubMed Central

Maynard, Jeffrey A.; Edwards, Alasdair J.; Guest, James R.; Rahbek, Carsten

2016-01-01

Coral spawning times have been linked to multiple environmental factors; however, to what extent these factors act as generalized cues across multiple species and large spatial scales is unknown. We used a unique dataset of coral spawning from 34 reefs in the Indian and Pacific Oceans to test if month of spawning and peak spawning month in assemblages of Acropora spp. can be predicted by sea surface temperature (SST), photosynthetically available radiation, wind speed, current speed, rainfall or sunset time. Contrary to the classic view that high mean SST initiates coral spawning, we found rapid increases in SST to be the best predictor in both cases (month of spawning: R2 = 0.73, peak: R2 = 0.62). Our findings suggest that a rapid increase in SST provides the dominant proximate cue for coral mass spawning over large geographical scales. We hypothesize that coral spawning is ultimately timed to ensure optimal fertilization success. PMID:27170709

Surface elevation dynamics in vegetated Spartina marshes versus unvegetated tidal ponds along the mid-Atlantic coast, USA, with implications to waterbirds

USGS Publications Warehouse

Erwin, R. Michael; Cahoon, Donald R.; Prosser, Diann J.; Sanders, Geoffrey; Hensel, Philippe

2006-01-01

Mid Atlantic coastal salt marshes contain a matrix of vegetation diversified by tidal pools, pannes, and creeks, providing habitats of varying importance to many species of breeding, migrating, and wintering waterbirds. We hypothesized that changes in marsh elevation were not sufficient to keep pace with those of sea level in both vegetated and unvegetated Spartina alterniflora sites at a number of mid lagoon marsh areas along the Atlantic coast. We also predicted that northern areas would suffer less of a deficit than would southern sites. Beginning in August 1998, we installed surface elevation tables at study sites on Cape Cod, Massachusetts, southern New Jersey, and two locations along Virginia's eastern shore. We compared these elevation changes over the 4-4.5 yr record with the long-term (> 50 yr) tidal records for each locale. We also collected data on waterbird use of these sites during all seasons of the year, based on ground surveys and replicated surveys from observation platforms. Three patterns of marsh elevation change were found. At Nauset Marsh, Cape Cod, the Spartina marsh surface tracked the pond surface, both keeping pace with regional sea-level rise rates. In New Jersey, the ponds are becoming deeper while marsh surface elevation remains unchanged from the initial reading. This may result in a submergence of the marsh in the future, assuming sea-level rise continues at current rates. Ponds at both Virginia sites are filling in, while marsh surface elevation rates do not seem to be keeping pace with local sea-level rise. An additional finding at all sites was that subsidence in the vegetated marsh surfaces was less than in unvegetated areas, reflecting the importance of the root mat in stabilizing sediments. The implications to migratory waterbirds are significant. Submergence of much of the lagoonal marsh area in Virginia and New Jersey over the next century could have major negative (i.e., flooding) effects on nesting populations of marsh-dependent seaside sparrows Ammodramus maritimus, saltmarsh sharp-tailed sparrows A. caudacutus, black rails Laterallus jamaicensis, clapper rails Rallus longirostris, Forster's terns Sterna forsteri, common terns Sterna hirundo, and gull-billed terns Sterna nilotica. Although short-term inundation of many lagoonal marshes may benefit some open-water feeding ducks, geese, and swans during winter, the long-term ecosystem effects may be detrimental, as wildlife resources will be lost or displaced. With the reduction in area of emergent marsh, estuarine secondary productivity and biotic diversity will also be reduced.

Food safety using NMR-based metabolomics: Assessment of the Atlantic bluefin tuna, Thunnus thynnus, from the Mediterranean Sea.

PubMed

Cappello, Tiziana; Giannetto, Alessia; Parrino, Vincenzo; De Marco, Giuseppe; Mauceri, Angela; Maisano, Maria

2018-05-01

Seafood is a valuable component of human diet because of its nutritional properties. The Atlantic bluefin tuna Thunnus thynnus is a scombroid fish highly appreciated as seafood worldwide. Being a top pelagic predator, concerns have been raised over human health risks due to its consumption. Therefore, herein it was comprehensively evaluated the health status and potential metabolite shifts between sexes of bluefin tuna from the Mediterranean Sea, proved to bioaccumulate environmental obesogens, namely polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) at hepatic level. To this aim, nuclear magnetic resonance (NMR)-based metabolomics was applied on liver of post-spawning tuna. Findings from this study pointed out that hepatic bioaccumulation of PCBs and OCPs induced differential metabolic disturbances between sexes, attributable to the reproductive stage at which tuna were caught. Alterations were mainly found in energy-producing metabolic pathways (with changes in acetate, acetoacetate, malonate, and lactate), amino acid (with changes in BCAA, alanine, sarcosine, and tyrosine), and lipid (with changes in choline and phosphocholine) metabolism, with activation of fatty acids biosynthesis and ketogenesis in male tuna. Overall, according to the current European legislation on maximum levels of contaminants in seafood, the consumption of bluefin tuna does not represent a risk for human health. Copyright © 2018 Elsevier Ltd. All rights reserved.

Movement, migration, and smolting of Atlantic salmon (Salmo salar)

USGS Publications Warehouse

McCormick, S.D.; Hansen, Lonnie P.; Quinn, T.P.; Saunders, R.L.

1998-01-01

A variety of movements characterize the behavioral plasticity of Atlantic salmon (Salmo salar) in fresh water, including movements of fry from redds, establishment of feeding territories, spawning movements of sexually mature male parr, movement to and from winter habitat, and smolt migration in spring. Smolting is an adaptive specialization for downstream migration, seawater entry, and marine residence. While still in fresh water, smolts become silvery and streamlined, lose their positive rheotaxis and territoriality, and begin schooling. Physiological changes include increased salinity tolerance, olfactory sensitivity, metabolic rate, scope for growth, and altered hemoglobin and visual pigments. Through their impact on the neuroendocrine system, photoperiod and temperature regulate physiological changes, whereas temperature and water flow may initiate migration. Smolt survival is affected by a limited period of readiness (a physiological 'smolt window') and the timing of seawater entry with environmental conditions such as temperature, food, and predators (an ecological 'smolt window'). Smolt development is adversely affected by acidity, pollutants, and improper rearing conditions, and is often more sensitive than other life stages. Unfortunately, the migration corridor of smolts (mainstems of rivers and estuaries) are the most heavily impacted by pollution, dams, and other anthropogenic activities that may be directly lethal or increase mortality by delaying or inhibiting smolt migration.

Morphological differences in parr of Atlantic salmon Salmo salar from three regions in Norway.

PubMed

Solem, O; Berg, O K

2011-05-01

Morphological characters were compared in parr (total length 33-166 mm) of Atlantic salmon Salmo salar sampled from eight wild populations in three regions, three in northern, two in the middle and three in southern Norway, covering a distance of 1700 km (from 70° N to 58° N). On the basis of morphological characters 94·6% of the individuals were correctly classified into the three regions. Discrimination between populations within these three regions also had a high degree of correct classification (89·0-95·8%). Principle component analysis identified largest differences to be in head characters, notably eye diameter and jawbone, with the smallest diameter and head size among the northernmost populations. Fish from the southern rivers had a deeper body form whereas fish from the middle region had larger heads and pectoral fins. This illustrates that S. salar already in the early parr stage has morphological traits, which can be used in discrimination between regions and populations and that these differences are discernible in spite of the volume of escaped farmed fish spawning in Norwegian rivers during the past 30 years. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

Reduced fitness of Atlantic salmon released in the wild after one generation of captive breeding

PubMed Central

Milot, Emmanuel; Perrier, Charles; Papillon, Lucie; Dodson, Julian J; Bernatchez, Louis

2013-01-01

Salmonids rank among the most socioeconomically valuable fishes and the most targeted species by stocking with hatchery-reared individuals. Here, we used molecular parentage analysis to assess the reproductive success of wild- and hatchery-born Atlantic salmon over three consecutive years in a small river in Québec. Yearly restocking in this river follows a single generation of captive breeding. Among the adults returning to the river to spawn, between 11% and 41% each year were born in hatchery. Their relative reproductive success (RRS) was nearly half that of wild-born fish (0.55). RRS varied with life stage, being 0.71 for fish released at the fry stage and 0.42 for fish released as smolt. The lower reproductive success of salmon released as smolt was partly mediated by the modification of the proportion of single-sea-winter/multi-sea-winter fish. Overall, our results suggest that modifications in survival and growth rates alter the life-history strategies of these fish at the cost of their reproductive success. Our results underline the potential fitness decrease, warn on long-term evolutionary consequences for the population of repeated stocking and support the adoption of more natural rearing conditions for captive juveniles and their release at a younger stage, such as unfed fry. PMID:23745139

Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a "silver wave" hypothesis

USGS Publications Warehouse

Lok, E.K.; Esler, Daniel N.; Takekawa, John Y.; De La Cruz, S.W.; Boyd, W.S.; Nysewander, D.R.; Evenson, J.R.; Ward, D.H.

2012-01-01

Surf scoters Melanitta perspicillata are sea ducks that aggregate at spawning events of Pacific herring Clupea pallasi and forage on the eggs, which are deposited in abundance during spring at discrete sites. We evaluated whether migrating scoters followed a ‘silver wave’ of resource availability, analogous to the ‘green wave’ of high-quality foraging conditions that herbivorous waterfowl follow during spring migration. We confirmed that herring spawning activity began later in the year at higher latitudes, creating a northward-progressing wave of short-term localized food availability. Using satellite telemetry and aerial surveys, we documented the chronology of scoter spring migration and the use of stopover locations in relation to herring spawn timing and locations. We found that the migration chronology paralleled the northward progression of herring spawning events. Although there was considerable variability in the timing of both scoter migration and the initiation of herring spawning, the processes were related beyond a coincidental northward progression. During migration, 60% of the tracked scoters visited at least 1 spawn site, and those that used spawn sites were located on spawn sites for approximately one-third of their migration locations. Surf scoters showed close spatiotemporal associations with herring spawning events, confirming that the presence of herring spawn was a factor determining habitat use for many individuals. Surf scoters showed close spatiotemporal associations with herring spawning events, confirming that the presence of herring spawn was a factor determining habitat use for many individuals, a conclusion that is consistent with previous studies which used physiologically based metrics to evaluate the importance of herring spawn.

Oceanic migration and spawning of anguillid eels.

PubMed

Tsukamoto, K

2009-06-01

Many aspects of the life histories of anguillid eels have been revealed in recent decades, but the spawning migrations of their silver eels in the open ocean still remains poorly understood. This paper overviews what is known about the migration and spawning of anguillid species in the ocean. The factors that determine exactly when anguillid eels will begin their migrations are not known, although environmental influences such as lunar cycle, rainfall and river discharge seem to affect their patterns of movement as they migrate towards the ocean. Once in the ocean on their way to the spawning area, silver eels probably migrate in the upper few hundred metres, while reproductive maturation continues. Although involvement of a magnetic sense or olfactory cues seems probable, how they navigate or what routes they take are still a matter of speculation. There are few landmarks in the open ocean to define their spawning areas, other than oceanographic or geological features such as oceanic fronts or seamounts in some cases. Spawning of silver eels in the ocean has never been observed, but artificially matured eels of several species have exhibited similar spawning behaviours in the laboratory. Recent collections of mature adults and newly spawned preleptocephali in the spawning area of the Japanese eel Anguilla japonica have shown that spawning occurs during new moon periods in the North Equatorial Current region near the West Mariana Ridge. These data, however, show that the latitude of the spawning events can change among months and years depending on oceanographic conditions. Changes in spawning location of this and other anguillid species may affect their larval transport and survival, and appear to have the potential to influence recruitment success. A greater understanding of the spawning migration and the choice of spawning locations by silver eels is needed to help conserve declining anguillid species.

Upstream movements of Atlantic Salmon in the Lower Penobscot River, Maine following two dam removals and fish passage modifications

USGS Publications Warehouse

Izzo, Lisa K.; Maynard, George A.; Zydlewski, Joseph D.

2016-01-01

The Penobscot River Restoration Project (PRRP), to be completed in 2016, involved an extensive plan of dam removal, increases in hydroelectric capacity, and fish passage modifications to increase habitat access for diadromous species. As part of the PRRP, Great Works and Veazie dams were removed, making Milford Dam the first impediment to federally endangered Atlantic Salmon Salmo salar. Upstream habitat access for Atlantic Salmon is dependent upon successful and timely passage at Milford Dam because nearly all suitable spawning habitat is located upstream. In 2014 and 2015, a total of 73 adult salmon were radio-tagged to track their upstream movements through the Penobscot River to assess potential delays at (1) the dam remnants, (2) the confluence of the Stillwater Branch and the main stem of the Penobscot River below the impassable Orono Dam, and (3) the Milford Dam fish lift (installed in 2014). Movement rates through the dam remnants and the Stillwater confluence were comparable to open river reaches. Passage efficiency of the fish lift was high in both years (95% and 100%). However, fish experienced long delays at Milford Dam, with approximately one-third of fish taking more than a week to pass in each year, well below the Federal Energy Regulatory Commission passage standard of 95% within 48 h. Telemetry indicates most fish locate the fishway entrance within 5 h of arrival and were observed at the entrance at all hours of the day. These data indicate that overall transit times through the lower river were comparable to reported movement rates prior to changes to the Penobscot River due to the substantial delays seen at Milford Dam. The results of this study show that while adult Atlantic Salmon locate the new fish lift entrance quickly, passage of these fish was significantly delayed under 2014–2015 operations.

Temporal constraints on the potential role of fry odors as cues of past reproductive success for spawning lake trout

USGS Publications Warehouse

Buchinger, Tyler J.; Marsden, J. Ellen; Binder, Thomas R.; Huertas, Mar; Bussy, Ugo; Li, Ke; Hanson, James E.; Krueger, Charles C.; Li, Weiming; Johnson, Nicholas

2017-01-01

Deciding where to reproduce is a major challenge for most animals. Many select habitats based upon cues of successful reproduction by conspecifics, such as the presence of offspring from past reproductive events. For example, some fishes select spawning habitat following odors released by juveniles whose rearing habitat overlaps with spawning habitat. However, juveniles may emigrate before adults begin to search for spawning habitat; hence, the efficacy of juvenile cues could be constrained by degradation or dissipation rates. In lake trout (Salvelinus namaycush), odors deposited by the previous year's offspring have been hypothesized to guide adults to spawning reefs. However, in most extant populations, lake trout fry emigrate from spawning reefs during the spring and adults spawn during the fall. Therefore, we postulated that the role of fry odors in guiding habitat selection might be constrained by the time between fry emigration and adult spawning. Time course chemical, physiological, and behavioral assays indicated that the odors deposited by fry likely degrade or dissipate before adults select spawning habitats. Furthermore, fry feces did not attract wild lake trout to constructed spawning reefs in Lake Huron. Taken together, our results indicate fry odors are unlikely to act as cues for lake trout searching for spawning reefs in populations whose juveniles emigrate before the spawning season, and underscore the importance of environmental constraints on social cues.

Environmental and biological cues for spawning in the crown-of-thorns starfish

PubMed Central

Pratchett, Morgan S.

2017-01-01

Sporadic outbreaks of the coral-eating crown-of-thorns starfish are likely to be due, at least in part, to spatial and temporal variation in reproductive and settlement success. For gonochoric and broadcast spawning species such as crown-of-thorns starfish, spawning synchrony is fundamental for achieving high rates of fertilization. Highly synchronized gamete release within and among distinct populations is typically the result of the entrainment of neurohormonal endogenous rhythms by cues from the environment. In this study, we conducted multiple spawning assays to test the effects of temperature change, reduced salinity and nutrient enrichment of seawater, phytoplankton, gametes (sperm and eggs), and the combined effect of sperm and phytoplankton on the likelihood of spawning in male and female crown-of-thorns starfish. We also investigated sex-specific responses to each of these potential spawning cues. We found that (1) abrupt temperature change (an increase of 4°C) induced spawning in males, but less so in females; (2) males often spawned in response to the presence of phytoplankton, but none of the females spawned in response to these cues; (3) the presence of sperm in the water column induced males and females to spawn, although additive and synergistic effects of sperm and phytoplankton were not significant; and (4) males are more sensitive to the spawning cues tested and most likely spawn prior to females. We propose that environmental cues act as spawning ‘inducers’ by causing the release of hormones (gonad stimulating substance) in sensitive males, while biological cues (pheromones) from released sperm, in turn, act as spawning ‘synchronizers’ by triggering a hormonal cascade resulting in gamete shedding by conspecifics. Given the immediate temporal linkage between the timing of spawning and fertilization events, variability in the extent and synchronicity of gamete release will significantly influence reproductive success and may account for fluctuations in the abundance of crown-of-thorns starfish. PMID:28355236

Inter-annual variability of North Sea plaice spawning habitat

NASA Astrophysics Data System (ADS)

Loots, C.; Vaz, S.; Koubbi, P.; Planque, B.; Coppin, F.; Verin, Y.

2010-11-01

Potential spawning habitat is defined as the area where environmental conditions are suitable for spawning to occur. Spawning adult data from the first quarter (January-March) of the International Bottom Trawl Survey have been used to study the inter-annual variability of the potential spawning habitat of North Sea plaice from 1980 to 2007. Generalised additive models (GAM) were used to create a model that related five environmental variables (depth, bottom temperature and salinity, seabed stress and sediment type) to presence-absence and abundance of spawning adults. Then, the habitat model was applied each year from 1970 to 2007 to predict inter-annual variability of the potential spawning habitat. Predicted responses obtained by GAM for each year were mapped using kriging. A hierarchical classification associated with a correspondence analysis was performed to cluster spawning suitable areas and to determine how they evolved across years. The potential spawning habitat was consistent with historical spawning ground locations described in the literature from eggs surveys. It was also found that the potential spawning habitat varied across years. Suitable areas were located in the southern part of the North Sea and along the eastern coast of England and Scotland in the eighties; they expanded further north from the nineties. Annual survey distributions did not show such northward expansion and remained located in the southern North Sea. This suggests that this species' actual spatial distribution remains stable against changing environmental conditions, and that the potential spawning habitat is not fully occupied. Changes in environmental conditions appear to remain within plaice environmental ranges, meaning that other factors may control the spatial distribution of plaice spawning habitat.

Interannual variability in reproductive traits of the Patagonian toothfish Dissostichus eleginoides around the sub-Antarctic island of South Georgia.

PubMed

Brigden, K E; Marshall, C T; Scott, B E; Young, E F; Brickle, P

2017-07-01

Commercial fisheries data, collected as part of an observer programme and covering the period 1997-2014, were utilized in order to define key reproductive traits and spawning dynamics of the Patagonian toothfish Dissostichus eleginoides at South Georgia. Multi-year spawning site fidelity of D. eleginoides was revealed through the identification of previously unknown spawning hotspots. Timing of female spawning was shown to have shifted later, leading to a shorter spawning duration. A decrease in length and mass of female and male spawning fish and a reduced number of large spawning fish was found, evidence of a change in size structure of spawning D. eleginoides. During the study period fewer later maturity stage females (including spawning stage) were observed in conjunction with increased proportions of early stage female D. eleginoides. The findings are discussed in the context of reproductive success, with consideration of the possible effects such spawning characteristics and behaviours may have on egg and larval survival. This work presents the first long-term assessment of D. eleginoides spawning dynamics at South Georgia and provides valuable knowledge for both the ecology of the species and for future fisheries management of this commercially important species. © 2017 The Fisheries Society of the British Isles.

Evidence of sound production by spawning lake trout (Salvelinus namaycush) in lakes Huron and Champlain

USGS Publications Warehouse

Johnson, Nicholas S.; Higgs, Dennis; Binder, Thomas R.; Marsden, J. Ellen; Buchinger, Tyler John; Brege, Linnea; Bruning, Tyler; Farha, Steve A.; Krueger, Charles C.

2018-01-01

Two sounds associated with spawning lake trout (Salvelinus namaycush) in lakes Huron and Champlain were characterized by comparing sound recordings to behavioral data collected using acoustic telemetry and video. These sounds were named growls and snaps, and were heard on lake trout spawning reefs, but not on a non-spawning reef, and were more common at night than during the day. Growls also occurred more often during the spawning period than the pre-spawning period, while the trend for snaps was reversed. In a laboratory flume, sounds occurred when male lake trout were displaying spawning behaviors; growls when males were quivering and parallel swimming, and snaps when males moved their jaw. Combining our results with the observation of possible sound production by spawning splake (Salvelinus fontinalis × Salvelinus namaycush hybrid), provides rare evidence for spawning-related sound production by a salmonid, or any other fish in the superorder Protacanthopterygii. Further characterization of these sounds could be useful for lake trout assessment, restoration, and control.

Spawning of the kissing loach (Leptobotia curta) is limited to periods following the formation of temporary waters.

PubMed

Abe, Tsukasa; Kobayashi, Ichiro; Kon, Masahiro; Sakamoto, Tatsuya

2007-09-01

The kissing loach, an endangered species surviving only in a few Japanese rivers, spawns in the rice-field areas after migration from rivers in early June. To characterize the environmental conditions required for spawning of the kissing loach, spawning was assessed for two years both by direct observation of spawning behavior and by the appearance of eggs, larvae, and juveniles from June to October. All spawning of the kissing loach was limited to within a couple of days after the formation of temporary waters by remarkable rises in water level. Water temperature and daily rainfall fluctuated during the investigation periods, and no clear relationships with spawning were detected. Furthermore, all spawning was observed only in temporary waters with terrestrial grasses. Thus, spawning of the kissing loach is rigidly limited spatio-temporally to after the formation of temporary waters over terrestrial vegetation. Appropriate management of temporary waters will be crucial for the continued existence of this species.

Redd Site Selection and Spawning Habitat Use by Fall Chinook Salmon: The Importance of Geomorphic Features in Large Rivers

PubMed

Geist; Dauble

1998-09-01

/ Knowledge of the three-dimensional connectivity between rivers and groundwater within the hyporheic zone can be used to improve the definition of fall chinook salmon (Oncorhynchus tshawytscha) spawning habitat. Information exists on the microhabitat characteristics that define suitable salmon spawning habitat. However, traditional spawning habitat models that use these characteristics to predict available spawning habitat are restricted because they can not account for the heterogeneous nature of rivers. We present a conceptual spawning habitat model for fall chinook salmon that describes how geomorphic features of river channels create hydraulic processes, including hyporheic flows, that influence where salmon spawn in unconstrained reaches of large mainstem alluvial rivers. Two case studies based on empirical data from fall chinook salmon spawning areas in the Hanford Reach of the Columbia River are presented to illustrate important aspects of our conceptual model. We suggest that traditional habitat models and our conceptual model be combined to predict the limits of suitable fall chinook salmon spawning habitat. This approach can incorporate quantitative measures of river channel morphology, including general descriptors of geomorphic features at different spatial scales, in order to understand the processes influencing redd site selection and spawning habitat use. This information is needed in order to protect existing salmon spawning habitat in large rivers, as well as to recover habitat already lost.KEY WORDS: Hyporheic zone; Geomorphology; Spawning habitat; Large rivers; Fall chinook salmon; Habitat management

Modeling the spawning strategies and larval survival of the Brazilian sardine (Sardinella brasiliensis)

NASA Astrophysics Data System (ADS)

Dias, Daniela Faggiani; Pezzi, Luciano Ponzi; Gherardi, Douglas Francisco Marcolino; Camargo, Ricardo

2014-04-01

An Individual Based Model (IBM), coupled with a hydrodynamic model (ROMS), was used to investigate the spawning strategies and larval survival of the Brazilian Sardine in the South Brazil Bight (SBB). ROMS solutions were compared with satellite and field data to assess their representation of the physical environment. Two spawning experiments were performed for the summer along six years, coincident with ichthyoplankton survey cruises. In the first one, eggs were released in spawning habitats inferred from a spatial model. The second experiment simulated a random spawning to test the null hypothesis that there are no preferred spawning sites. Releasing eggs in the predefined spawning habitats increases larval survival, suggesting that the central-southern part of the SBB is more suitable for larvae development because of its thermodynamic characteristics. The Brazilian sardine is also capable of exploring suitable areas for spawning, according to the interannual variability of the SBB. The influence of water temperature, the presence of Cape Frio upwelling, and surface circulation on the spawning process was tested. The Cape Frio upwelling plays an important role in the modulation of Brazilian sardine spawning zones over SBB because of its lower than average water temperature. This has a direct influence on larval survival and on the interannual variability of the Brazilian sardine spawning process. The hydrodynamic condition is crucial in determining the central-southern part of SBB as the most suitable place for spawning because it enhances simulated coastal retention of larvae.

Franz Josef Land: extreme northern outpost for Arctic fishes

PubMed Central

Chernova, Natalia V.; Turchik, Alan; Sala, Enric

2014-01-01

The remote Franz Josef Land (FJL) Archipelago is the most northerly land in Eurasia and its fish fauna, particularly in nearshore habitats, has been poorly studied. An interdisciplinary expedition to FJL in summer 2013 used scuba, seines, and plankton nets to comprehensively study the nearshore fish fauna of the archipelago. We present some of the first underwater images for many of these species in their natural habitats. In addition, deep water drop cameras were deployed between 32 and 392 m to document the fish fauna and their associated habitats at deeper depths. Due to its high latitude (79°–82°N), extensive ice cover, and low water temperatures (<0 °C much of the year), the fish diversity at FJL is low compared to other areas of the Barents Sea. Sixteen species of fishes from seven families were documented on the expedition, including two species previously unknown to the region. One Greenland shark, Somniosus microcephalus (Somniosidae), ca. 2 m in length, was recorded by drop camera near Hayes Island at 211 m, and Esipov’s pout, Gymnelus esipovi (Zoarcidae), was collected at Wilton Island at 15 m in a kelp forest. Including the tape-body pout, Gymnelus taeniatus, described earlier from the sub-littoral zone of Kuhn Island, 17 fish species are now known from FJL’s nearshore waters. Species endemic to the Arctic accounted for 75% of the nearshore species observed, followed by species with wider ranges. A total of 43 species from 15 families are known from FJL with the majority of the records from offshore trawl surveys between 110 and 620 m. Resident species have mainly high Arctic distributions, while transient species visit the archipelago to feed (e.g., Greenland shark), and others are brought by currents as larvae and later migrate to spawn grounds in the south (e.g., Atlantic cod Gadus morhua, Capelin Mallotus villosus, Beaked redfish Sebastes mentella). Another species group includes warmer-water fishes that are rare waifs (e.g., Glacier lanternfish Benthosema glaciale, White barracudina Arctozenus rissoi). The rapid warming of the Arctic will likely result in significant changes to the entire ecosystem and this study therefore serves as an important baseline for the nearshore fish assemblages in this unique and fragile region. PMID:25538869