Historical Population Estimates For Several Fish Species At Offshore Oil and Gas Structures in the US Gulf of Mexico

NASA Astrophysics Data System (ADS)

Gitschlag, G.

2016-02-01

Population estimates were calculated for four fish species occurring at offshore oil and gas structures in water depths of 14-32 m off the Louisiana and upper Texas coasts in the US Gulf of Mexico. From 1993-1999 sampling was conducted at eight offshore platforms in conjunction with explosive salvage of the structures. To estimate fish population size prior to detonation of explosives, a fish mark-recapture study was conducted. Fish were captured on rod and reel using assorted hook sizes. Traps were occasionally used to supplement catches. Fish were tagged below the dorsal fin with plastic t-bar tags using tagging guns. Only fish that were alive and in good condition were released. Recapture sampling was conducted after explosives were detonated during salvage operations. Personnel operating from inflatable boats used dip nets to collect all dead fish that floated to the surface. Divers collected representative samples of dead fish that sank to the sea floor. Data provided estimates for red snapper (Lutjanus campechanus), Atlantic spadefish (Chaetodipterus faber), gray triggerfish (Balistes capriscus), and blue runner (Caranx crysos) at one or more of the eight platforms studied. At seven platforms, population size for red snapper was calculated at 503-1,943 with a 95% CI of 478. Abundance estimates for Atlantic spadefish at three platforms ranged from 1,432-1,782 with a 95% CI of 473. At three platforms, population size of gray triggerfish was 63-129 with a 95% CI of 82. Blue runner abundance at one platform was 558. Unlike the other three species which occur close to the platforms, blue runner range widely and recapture of this species was dependent on fish schools being in close proximity to the platform at the time explosives were detonated. Tag recapture was as high as 73% for red snapper at one structure studied.

[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.

Effects of human population density and proximity to markets on coral reef fishes vulnerable to extinction by fishing.

PubMed

Brewer, T D; Cinner, J E; Green, A; Pressey, R L

2013-06-01

Coral reef fisheries are crucial to the livelihoods of tens of millions of people; yet, widespread habitat degradation and unsustainable fishing are causing severe depletion of stocks of reef fish. Understanding how social and economic factors, such as human population density, access to external markets, and modernization interact with fishing and habitat degradation to affect fish stocks is vital to sustainable management of coral reef fisheries. We used fish survey data, national social and economic data, and path analyses to assess whether these factors explain variation in biomass of coral reef fishes among 25 sites in Solomon Islands. We categorized fishes into 3 groups on the basis of life-history characteristics associated with vulnerability to extinction by fishing (high, medium, and low vulnerability). The biomass of fish with low vulnerability was positively related to habitat condition. The biomass of fishes with high vulnerability was negatively related to fishing conducted with efficient gear. Use of efficient gear, in turn, was strongly and positively related to both population density and market proximity. This result suggests local population pressure and external markets have additive negative effects on vulnerable reef fish. Biomass of the fish of medium vulnerability was not explained by fishing intensity or habitat condition, which suggests these species may be relatively resilient to both habitat degradation and fishing. © 2012 Society for Conservation Biology.

Compensatory mechanisms in fish populations: Literature reviews: Volume 2, Compensation in fish populations subject to catastrophic impact: Final report

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

Jude, D.J.; Mansfield, P.J.; Schneeberger, P.J.

1987-05-01

This study comprises an extensive literature review, critical evaluations of case histories, and considered recommendations for future research on the mechanisms and extent of compensation by various fish species subject to catastrophic impacts. ''Catastrophic impact'' was defined as an event which removes some limitation (such as food or space) on a fish population. Those events studied included new species introduction, toxic spills, exploitation of specific fish populations, and drawdown. The fish studied each had more than one compensatory mechanism available, and thus were able to respond to a catastrophic event even if an option was removed. Predation, overfishing, competition, disease,more » and parasitism are all potential catastrophies, but were found not to cause a catastrophic impact (except in special cases). In general, compensatory responses were determined to vary widely, even for species which perform fairly similar functions in an ecosystem. The extensive nature of this study, however, pointed up the many data gaps in the existing literature; recommendations are therefore made for followup research and expansion of ongoing monitoring programs, based on an evaluation of their relative importance.« less

Climate change effects on North American inland fish populations and assemblages

USGS Publications Warehouse

Lynch, Abigail J.; Myers, Bonnie; Chu, Cindy; Eby, Lisa A.; Falke, Jeffrey A.; Kovach, Ryan P.; Krabbenhoft, Trevor J.; Kwak, Thomas J.; Lyons, John; Paukert, Craig P.; Whitney, James E.

2016-01-01

Climate is a critical driver of many fish populations, assemblages, and aquatic communities. However, direct observational studies of climate change impacts on North American inland fishes are rare. In this synthesis, we (1) summarize climate trends that may influence North American inland fish populations and assemblages, (2) compile 31 peer-reviewed studies of documented climate change effects on North American inland fish populations and assemblages, and (3) highlight four case studies representing a variety of observed responses ranging from warmwater systems in the southwestern and southeastern United States to coldwater systems along the Pacific Coast and Canadian Shield. We conclude by identifying key data gaps and research needs to inform adaptive, ecosystem-based approaches to managing North American inland fishes and fisheries in a changing climate.

Effects of fire on fish populations: Landscape perspectives on persistence of native fishes and nonnative fish invasions

Treesearch

Jason B. Dunham; Michael K. Young; Robert E. Gresswell; Bruce E. Rieman

2003-01-01

Our limited understanding of the short and long-term effects of fire on fish contributes to considerable uncertainty in assessments of the risks and benefits of fire management alternatives. A primary concern among the many potential effects of fire is the effects of fire and fire management on persistence of native fish populations. Limited evidence suggests...

First genealogy for a wild marine fish population reveals multigenerational philopatry.

PubMed

Salles, Océane C; Pujol, Benoit; Maynard, Jeffrey A; Almany, Glenn R; Berumen, Michael L; Jones, Geoffrey P; Saenz-Agudelo, Pablo; Srinivasan, Maya; Thorrold, Simon R; Planes, Serge

2016-11-15

Natal philopatry, the return of individuals to their natal area for reproduction, has advantages and disadvantages for animal populations. Natal philopatry may generate local genetic adaptation, but it may also increase the probability of inbreeding that can compromise persistence. Although natal philopatry is well documented in anadromous fishes, marine fish may also return to their birth site to spawn. How philopatry shapes wild fish populations is, however, unclear because it requires constructing multigenerational pedigrees that are currently lacking for marine fishes. Here we present the first multigenerational pedigree for a marine fish population by repeatedly genotyping all individuals in a population of the orange clownfish (Amphiprion percula) at Kimbe Island (Papua New Guinea) during a 10-y period. Based on 2927 individuals, our pedigree analysis revealed that longitudinal philopatry was recurrent over five generations. Progeny tended to settle close to their parents, with related individuals often sharing the same colony. However, successful inbreeding was rare, and genetic diversity remained high, suggesting occasional inbreeding does not impair local population persistence. Local reproductive success was dependent on the habitat larvae settled into, rather than the habitat they came from. Our study suggests that longitudinal philopatry can influence both population replenishment and local adaptation of marine fishes. Resolving multigenerational pedigrees during a relatively short period, as we present here, provides a framework for assessing the ability of marine populations to persist and adapt to accelerating climate change.

First genealogy for a wild marine fish population reveals multigenerational philopatry

PubMed Central

Salles, Océane C.; Pujol, Benoit; Maynard, Jeffrey A.; Almany, Glenn R.; Berumen, Michael L.; Jones, Geoffrey P.; Saenz-Agudelo, Pablo; Srinivasan, Maya; Thorrold, Simon R.; Planes, Serge

2016-01-01

Natal philopatry, the return of individuals to their natal area for reproduction, has advantages and disadvantages for animal populations. Natal philopatry may generate local genetic adaptation, but it may also increase the probability of inbreeding that can compromise persistence. Although natal philopatry is well documented in anadromous fishes, marine fish may also return to their birth site to spawn. How philopatry shapes wild fish populations is, however, unclear because it requires constructing multigenerational pedigrees that are currently lacking for marine fishes. Here we present the first multigenerational pedigree for a marine fish population by repeatedly genotyping all individuals in a population of the orange clownfish (Amphiprion percula) at Kimbe Island (Papua New Guinea) during a 10-y period. Based on 2927 individuals, our pedigree analysis revealed that longitudinal philopatry was recurrent over five generations. Progeny tended to settle close to their parents, with related individuals often sharing the same colony. However, successful inbreeding was rare, and genetic diversity remained high, suggesting occasional inbreeding does not impair local population persistence. Local reproductive success was dependent on the habitat larvae settled into, rather than the habitat they came from. Our study suggests that longitudinal philopatry can influence both population replenishment and local adaptation of marine fishes. Resolving multigenerational pedigrees during a relatively short period, as we present here, provides a framework for assessing the ability of marine populations to persist and adapt to accelerating climate change. PMID:27799530

Understanding and managing fish populations: keeping the toolbox fit for purpose.

PubMed

Paris, J R; Sherman, K D; Bell, E; Boulenger, C; Delord, C; El-Mahdi, M B M; Fairfield, E A; Griffiths, A M; Gutmann Roberts, C; Hedger, R D; Holman, L E; Hooper, L H; Humphries, N E; Katsiadaki, I; King, R A; Lemopoulos, A; Payne, C J; Peirson, G; Richter, K K; Taylor, M I; Trueman, C N; Hayden, B; Stevens, J R

2018-03-01

Wild fish populations are currently experiencing unprecedented pressures, which are projected to intensify in the coming decades. Developing a thorough understanding of the influences of both biotic and abiotic factors on fish populations is a salient issue in contemporary fish conservation and management. During the 50th Anniversary Symposium of The Fisheries Society of the British Isles at the University of Exeter, UK, in July 2017, scientists from diverse research backgrounds gathered to discuss key topics under the broad umbrella of 'Understanding Fish Populations'. Below, the output of one such discussion group is detailed, focusing on tools used to investigate natural fish populations. Five main groups of approaches were identified: tagging and telemetry; molecular tools; survey tools; statistical and modelling tools; tissue analyses. The appraisal covered current challenges and potential solutions for each of these topics. In addition, three key themes were identified as applicable across all tool-based applications. These included data management, public engagement, and fisheries policy and governance. The continued innovation of tools and capacity to integrate interdisciplinary approaches into the future assessment and management of fish populations is highlighted as an important focus for the next 50 years of fisheries research. © 2018 The Fisheries Society of the British Isles.

Comparative Analysis of State Fish Consumption Advisories Targeting Sensitive Populations

PubMed Central

Scherer, Alison C.; Tsuchiya, Ami; Younglove, Lisa R.; Burbacher, Thomas M.; Faustman, Elaine M.

2008-01-01

Objective Fish consumption advisories are issued to warn the public of possible toxicological threats from consuming certain fish species. Although developing fetuses and children are particularly susceptible to toxicants in fish, fish also contain valuable nutrients. Hence, formulating advice for sensitive populations poses challenges. We conducted a comparative analysis of advisory Web sites issued by states to assess health messages that sensitive populations might access. Data sources We evaluated state advisories accessed via the National Listing of Fish Advisories issued by the U.S. Environmental Protection Agency. Data extraction We created criteria to evaluate advisory attributes such as risk and benefit message clarity. Data synthesis All 48 state advisories issued at the time of this analysis targeted children, 90% (43) targeted pregnant women, and 58% (28) targeted women of childbearing age. Only six advisories addressed single contaminants, while the remainder based advice on 2–12 contaminants. Results revealed that advisories associated a dozen contaminants with specific adverse health effects. Beneficial health effects of any kind were specifically associated only with omega-3 fatty acids found in fish. Conclusions These findings highlight the complexity of assessing and communicating information about multiple contaminant exposure from fish consumption. Communication regarding potential health benefits conferred by specific fish nutrients was minimal and focused primarily on omega-3 fatty acids. This overview suggests some lessons learned and highlights a lack of both clarity and consistency in providing the breadth of information that sensitive populations such as pregnant women need to make public health decisions about fish consumption during pregnancy. PMID:19079708

PROJECTING THE RESPONSE OF FISH POPULATION GROWTH RATE TO SEDIMENT EXPOSURE

EPA Science Inventory

Sediment is one of the main stressors on stream fish populations in Georgia. Here, a quantitative approach relating sediment exposure to stream fish population dynamics is presented, where equations characterize sediment exposure to vital rates, then vital rates are used in a mat...

Big Spring spinedace and associated fish populations and habitat conditions in Condor Canyon, Meadow Valley Wash, Nevada

USGS Publications Warehouse

Jezorek, Ian G.; Connolly, Patrick J.; Munz, Carrie S.; Dixon, Chris

2011-01-01

Executive Summary: This project was designed to document habitat conditions and populations of native and non-native fish within the 8-kilometer Condor Canyon section of Meadow Valley Wash, Nevada, with an emphasis on Big Spring spinedace (Lepidomeda mollispinis pratensis). Other native fish present were speckled dace (Rhinichthys osculus) and desert sucker (Catostomus clarki). Big Spring spinedace were known to exist only within this drainage and were known to have been extirpated from a portion of their former habitat located downstream of Condor Canyon. Because of this extirpation and the limited distribution of Big Spring spinedace, the U.S. Fish and Wildlife Service listed this species as threatened under the Endangered Species Act in 1985. Prior to our effort, little was known about Big Spring spinedace populations or life histories and habitat associations. In 2008, personnel from the U.S. Geological Survey's Columbia River Research Laboratory began surveys of Meadow Valley Wash in Condor Canyon. Habitat surveys characterized numerous variables within 13 reaches, thermologgers were deployed at 9 locations to record water temperatures, and fish populations were surveyed at 22 individual sites. Additionally, fish were tagged with Passive Integrated Transponder (PIT) tags, which allowed movement and growth information to be collected on individual fish. The movements of tagged fish were monitored with a combination of recapture events and stationary in-stream antennas, which detected tagged fish. Meadow Valley Wash within Condor Canyon was divided by a 12-meter (m) waterfall known as Delmue Falls. About 6,100 m of stream were surveyed downstream of the falls and about 2,200 m of stream were surveyed upstream of the falls. Although about three-quarters of the surveyed stream length was downstream of Delmue Falls, the highest densities and abundance of native fish were upstream of the falls. Big Spring spinedace and desert sucker populations were highest near the

Social-ecological interactions, management panaceas, and the future of wild fish populations

PubMed Central

van Poorten, Brett T.; Arlinghaus, Robert; Daedlow, Katrin; Haertel-Borer, Susanne S.

2011-01-01

We explored the social and ecological outcomes associated with emergence of a management panacea designed to govern a stochastic renewable natural resource. To that end, we constructed a model of a coupled social-ecological system of recreational fisheries in which a manager supports naturally fluctuating stocks by stocking fish in response to harvest-driven satisfaction of resource users. The realistic assumption of users remembering past harvest experiences when exploiting a stochastically fluctuating fish population facilitates the emergence of a stocking-based management panacea over time. The social benefits of panacea formation involve dampening natural population fluctuations and generating stability of user satisfaction. It also maintains the resource but promotes the eventual replacement of wild fish by hatchery-descended fish. Our analyses show this outcome is particularly likely when hatchery-descended fish are reasonably fit (e.g., characterized by similar survival relative to wild fish) and/or when natural recruitment of the wild population is low (e.g., attributable to habitat deterioration), which leaves the wild population with little buffer against competition by stocked fish. The potential for release-based panacea formation is particularly likely under user-based management regimes and should be common in a range of social-ecological systems (e.g., fisheries, forestry), whenever user groups are entitled to engage in release or replanting strategies. The net result will be the preservation of a renewable resource through user-based incentives, but the once natural populations are likely to be altered and to host nonnative genotypes. This risks other ecosystem services and the future of wild populations. PMID:21742983

Population maintenance among tropical reef fishes: Inferences from small-island endemics

PubMed Central

Robertson, D. Ross

2001-01-01

To what extent do local populations of tropical reef fishes persist through the recruitment of pelagic larvae to their natal reef? Endemics from small, isolated islands can help answer that question by indicating whether special biological attributes are needed for long-term survival under enforced localization in high-risk situations. Taxonomically and biologically, the endemics from seven such islands are broadly representative of their regional faunas. As natal-site recruitment occurs among reef fishes in much less isolated situations, these characteristics of island endemics indicate that a wide range of reef fishes could have persistent self-sustaining local populations. Because small islands regularly support substantial reef fish faunas, regional systems of small reserves could preserve much of the diversity of these fishes. PMID:11331752

The Impact of Marine Protected Areas on Reef-Wide Population Structure and Fishing-Induced Phenotypes in Coral-Reef Fishes

NASA Astrophysics Data System (ADS)

Fidler, Robert Young, III

Overfishing and destructive fishing practices threaten the sustainability of fisheries worldwide. In addition to reducing population sizes, anthropogenic fishing effort is highly size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-selective mortality induces widespread phenotypic shifts toward the predominance of smaller and earlier-maturing individuals. Fish that reach sexual maturity at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of exploited populations. These directional phenotypic alterations, collectively known as "fisheries-induced evolution" (FIE) are among the primary causes of the loss of harvestable fish biomass. Marine protected areas (MPAs) are one of the most widely utilized components of fisheries management programs around the world, and have been proposed as a potential mechanism by which the impacts of FIE may be mitigated. The ability of MPAs to buffer exploited populations against fishing pressure, however, remains debated due to inconsistent results across studies. Additionally, empirical evidence of phenotypic shifts in fishes within MPAs is lacking. This investigation addresses both of these issues by: (1) using a categorical meta-analysis of MPAs to standardize and quantify the magnitude of MPA impacts across studies; and (2) conducting a direct comparison of life-history phenotypes known to be influenced by FIE in six reef-fish species inside and outside of MPAs. The Philippines was used as a model system for analyses due to the country's significance in global marine biodiversity and reliance on MPAs as a fishery management tool. The quantitative impact of Philippine MPAs was assessed using a "reef-wide" meta-analysis. This analysis used pooled visual census data from 39 matched pairs of MPAs and fished reefs surveyed twice over a mean period of 3 years. In 17 of these MPAs, two additional surveys were conducted

Relative importance of population size, fishing pressure and temperature on the spatial distribution of nine Northwest Atlantic groundfish stocks.

PubMed

Adams, Charles F; Alade, Larry A; Legault, Christopher M; O'Brien, Loretta; Palmer, Michael C; Sosebee, Katherine A; Traver, Michele L

2018-01-01

The spatial distribution of nine Northwest Atlantic groundfish stocks was documented using spatial indicators based on Northeast Fisheries Science Center spring and fall bottom trawl survey data, 1963-2016. We then evaluated the relative importance of population size, fishing pressure and bottom temperature on spatial distribution with an information theoretic approach. Northward movement in the spring was generally consistent with prior analyses, whereas changes in depth distribution and area occupancy were not. Only two stocks exhibited the same changes in spatiotemporal distribution in the fall as compared with the spring. Fishing pressure was the most important predictor of the center of gravity (i.e., bivariate mean location of the population) for the majority of stocks in the spring, whereas in the fall this was restricted to the east-west component. Fishing pressure was also the most important predictor of the dispersion around the center of gravity in both spring and fall. In contrast, biomass was the most important predictor of area occupancy for the majority of stocks in both seasons. The relative importance of bottom temperature was ranked highest in the fewest number of cases. This study shows that fishing pressure, in addition to the previously established role of climate, influences the spatial distribution of groundfish in the Northwest Atlantic. More broadly, this study is one of a small but growing body of literature to demonstrate that fishing pressure has an effect on the spatial distribution of marine resources. Future work must consider both fishing pressure and climate when examining mechanisms underlying fish distribution shifts.

Relative importance of population size, fishing pressure and temperature on the spatial distribution of nine Northwest Atlantic groundfish stocks

PubMed Central

Alade, Larry A.; Legault, Christopher M.; O’Brien, Loretta; Palmer, Michael C.; Sosebee, Katherine A.; Traver, Michele L.

2018-01-01

The spatial distribution of nine Northwest Atlantic groundfish stocks was documented using spatial indicators based on Northeast Fisheries Science Center spring and fall bottom trawl survey data, 1963–2016. We then evaluated the relative importance of population size, fishing pressure and bottom temperature on spatial distribution with an information theoretic approach. Northward movement in the spring was generally consistent with prior analyses, whereas changes in depth distribution and area occupancy were not. Only two stocks exhibited the same changes in spatiotemporal distribution in the fall as compared with the spring. Fishing pressure was the most important predictor of the center of gravity (i.e., bivariate mean location of the population) for the majority of stocks in the spring, whereas in the fall this was restricted to the east-west component. Fishing pressure was also the most important predictor of the dispersion around the center of gravity in both spring and fall. In contrast, biomass was the most important predictor of area occupancy for the majority of stocks in both seasons. The relative importance of bottom temperature was ranked highest in the fewest number of cases. This study shows that fishing pressure, in addition to the previously established role of climate, influences the spatial distribution of groundfish in the Northwest Atlantic. More broadly, this study is one of a small but growing body of literature to demonstrate that fishing pressure has an effect on the spatial distribution of marine resources. Future work must consider both fishing pressure and climate when examining mechanisms underlying fish distribution shifts. PMID:29698454

Sampling characteristics and calibration of snorkel counts to estimate stream fish populations

USGS Publications Warehouse

Weaver, D.; Kwak, Thomas J.; Pollock, Kenneth

2014-01-01

Snorkeling is a versatile technique for estimating lotic fish population characteristics; however, few investigators have evaluated its accuracy at population or assemblage levels. We evaluated the accuracy of snorkeling using prepositioned areal electrofishing (PAE) for estimating fish populations in a medium-sized Appalachian Mountain river during fall 2008 and summer 2009. Strip-transect snorkel counts were calibrated with PAE counts in identical locations among macrohabitats, fish species or taxa, and seasons. Mean snorkeling efficiency (i.e., the proportion of individuals counted from the true population) among all taxa and seasons was 14.7% (SE, 2.5%), and the highest efficiencies were for River Chub Nocomis micropogon at 21.1% (SE, 5.9%), Central Stoneroller Campostoma anomalum at 20.3% (SE, 9.6%), and darters (Percidae) at 17.1% (SE, 3.7%), whereas efficiencies were lower for shiners (Notropis spp., Cyprinella spp., Luxilus spp.) at 8.2% (SE, 2.2%) and suckers (Catostomidae) at 6.6% (SE, 3.2%). Macrohabitat type, fish taxon, or sampling season did not significantly explain variance in snorkeling efficiency. Mean snorkeling detection probability (i.e., probability of detecting at least one individual of a taxon) among fish taxa and seasons was 58.4% (SE, 6.1%). We applied the efficiencies from our calibration study to adjust snorkel counts from an intensive snorkeling survey conducted in a nearby reach. Total fish density estimates from strip-transect counts adjusted for snorkeling efficiency were 7,288 fish/ha (SE, 1,564) during summer and 15,805 fish/ha (SE, 4,947) during fall. Precision of fish density estimates is influenced by variation in snorkeling efficiency and sample size and may be increased with additional sampling effort. These results demonstrate the sampling properties and utility of snorkeling to characterize lotic fish assemblages with acceptable efficiency and detection probability, less effort, and no mortality, compared with traditional

A moving target—incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations

USGS Publications Warehouse

Cooke, Steven J.; Martins, Eduardo G; Struthers, Daniel P; Gutowsky, Lee F G; Powers, Michael H.; Doka, Susan E.; Dettmers, John M.; Crook, David A; Lucas, Martyn C.; Holbrook, Christopher; Krueger, Charles C.

2016-01-01

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.

A moving target--incorporating knowledge of the spatial ecology of fish into the assessment and management of freshwater fish populations.

PubMed

Cooke, Steven J; Martins, Eduardo G; Struthers, Daniel P; Gutowsky, Lee F G; Power, Michael; Doka, Susan E; Dettmers, John M; Crook, David A; Lucas, Martyn C; Holbrook, Christopher M; Krueger, Charles C

2016-04-01

Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions.

Contaminant effects on Great Lakes' fish-eating birds: a population perspective

USGS Publications Warehouse

Heinz, G.H.; Kendall, Ronald J.; Dickerson, Richard L.; Giesy, John P.; Suk, William P.

1998-01-01

Preventing environmental contaminants from reducing wildlife populations is the greatest concern in wildlife toxicology. In the Great Lakes, environmental contaminants have a history of reducing populations of many species of fish-eating birds. Endocrine effects may have contributed to declines in fish-eating bird populations, but the overriding harm was caused by DDE-induced eggshell thinning. Toxic effects may still be occurring today, but apparently they are not of a sufficient magnitude to depress populations of most fish-eating birds. Once DDE levels in the Great Lakes declined, eggshells of birds began to get thicker and reproductive success improved. Populations of double-crested cormorants (Phalacrocorax auritus) and ring-billed gulls (Larus delawarensis) have increased dramatically since the bans on DDT and other organochlorine pesticides. Bald eagles (Haliaeetus leucocephalus) are still not reproducing at a normal rate along the shores of the Great Lakes, but success is much improved compared to earlier records when eggshell thinning was worse. Other species, such as herring gulls (Larus argentatus) and black-crowned night-herons (Nycticorax nycticorax), seem to be having improved reproductive success, but data on Great Lakes'-wide population changes are incomplete. Reproductive success of common terns (Sterna hirundo), Caspian terns (Sterna caspia), and Forster's terns (Sterna forsteri) seems to have improved in recent years, but, again, data on population changes are not very complete, and these birds face many habitat related problems as well as contaminant problems. Although contaminants are still producing toxic effects, and these effects may include endocrine disfunction, fish-eating birds in the Great Lakes seem to be largely weathering these effects, at least as far as populations are concerned. A lack of obvious contaminant effects on populations of fish-eating birds in the Great Lakes, however, should not be equated with a lack of any harm to

Replenishment of fish populations is threatened by ocean acidification

PubMed Central

Munday, Philip L.; Dixson, Danielle L.; McCormick, Mark I.; Meekan, Mark; Ferrari, Maud C. O.; Chivers, Douglas P.

2010-01-01

There is increasing concern that ocean acidification, caused by the uptake of additional CO2 at the ocean surface, could affect the functioning of marine ecosystems; however, the mechanisms by which population declines will occur have not been identified, especially for noncalcifying species such as fishes. Here, we use a combination of laboratory and field-based experiments to show that levels of dissolved CO2 predicted to occur in the ocean this century alter the behavior of larval fish and dramatically decrease their survival during recruitment to adult populations. Altered behavior of larvae was detected at 700 ppm CO2, with many individuals becoming attracted to the smell of predators. At 850 ppm CO2, the ability to sense predators was completely impaired. Larvae exposed to elevated CO2 were more active and exhibited riskier behavior in natural coral-reef habitat. As a result, they had 5–9 times higher mortality from predation than current-day controls, with mortality increasing with CO2 concentration. Our results show that additional CO2 absorbed into the ocean will reduce recruitment success and have far-reaching consequences for the sustainability of fish populations. PMID:20615968

Development of a spatially distributed model of fish population density for habitat assessment of rivers

NASA Astrophysics Data System (ADS)

Sui, Pengzhe; Iwasaki, Akito; Ryo, Masahiro; Saavedra, Oliver; Yoshimura, Chihiro

2013-04-01

Flow conditions play an important role in sustaining biodiversity of river ecosystem. However, their relations to freshwater fishes, especially to fish population density, have not been clearly described. This study, therefore, aimed to propose a new methodology to quantitatively link habitat conditions, including flow conditions and other physical conditions, to population density of fish species. We developed a basin-scale fish distribution model by integrating the concept of habitat suitability assessment with a distributed hydrological model (DHM) in order to estimate fish population density with particular attention to flow conditions. Generalized linear model (GLM) was employed to evaluate the relationship between population density of fish species and major environmental factors. The target basin was Sagami River in central Japan, where the river reach was divided into 10 sections by estuary, confluences of tributaries, and river-crossing structures (dams, weirs). The DHM was employed to simulate river discharge from 1998 to 2005, which was used to calculate 10 flow indices including mean discharge, 25th and 75th percentile discharge, duration of low and high flows, number of floods. In addition, 5 water quality parameters and 13 other physical conditions (such as basin area, river width, mean diameter of riverbed material, and number of river-crossing structures upstream and downstream) of each river section were considered as environmental variables. In case of Sagami River, 10 habitat variables among them were then selected based on their correlations to avoid multicollinearity. Finally, the best GLM was developed for each species based on Akaike's information criterion. As results, population densities of 16 fish species in Sagami River were modelled, and correlation coefficients between observed and calculated population densities for 10 species were more than 0.70. The key habitat factors for population density varied among fish species. Minimum

Recovery of a wild fish population from whole-lake additions of a synthetic estrogen.

PubMed

Blanchfield, Paul J; Kidd, Karen A; Docker, Margaret F; Palace, Vince P; Park, Brad J; Postma, Lianne D

2015-03-03

Despite widespread recognition that municipal wastewaters contain natural and synthetic estrogens, which interfere with development and reproduction of fishes in freshwaters worldwide, there are limited data on the extent to which natural populations of fish can recover from exposure to these compounds. We conducted whole-lake additions of an active component of the birth control pill (17α-ethynylestradiol; EE2) that resulted in the collapse of the fathead minnow (Pimephales promelas) population. Here we quantify physiological, population, and genetic characteristics of this population over the 7 years after EE2 additions stopped to determine if complete recovery was possible. By 3 years post-treatment, whole-body vitellogenin concentrations in male fathead minnow had returned to baseline, and testicular abnormalities were absent. In the spring of the fourth year, adult size-frequency distribution and abundance had returned to pretreatment levels. Microsatellite analyses clearly showed that postrecovery fish were descendants of the original EE2-treated population. Results from this whole-lake experiment demonstrate that fish can recover from EE2 exposure at the biochemical through population levels, although the timelines to do so are long for multigenerational exposures. These results suggest that wastewater treatment facilities that reduce discharges of estrogens and their mimics can improve the health of resident fish populations in their receiving environments.

ADAPTIONS OF WILD POPULATIONS OF THE ESTUARINE FISH FUNDULUS HETEROCLITUS TO PERSISTENT ENVIRONMENTAL CONTAMINANTS

EPA Science Inventory

Many aquatic species, including the estuarine fish Fundulus heteroclitus (mummichogs), adapt to local environmental conditions. We conducted studies to evaluate whether highly exposed populations of mummichogs adapt to toxic environmental contaminants. These fish populations are ...

Coral reef fish populations can persist without immigration

PubMed Central

Salles, Océane C.; Maynard, Jeffrey A.; Joannides, Marc; Barbu, Corentin M.; Saenz-Agudelo, Pablo; Almany, Glenn R.; Berumen, Michael L.; Thorrold, Simon R.; Jones, Geoffrey P.; Planes, Serge

2015-01-01

Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase. PMID:26582017

Coral reef fish populations can persist without immigration.

PubMed

Salles, Océane C; Maynard, Jeffrey A; Joannides, Marc; Barbu, Corentin M; Saenz-Agudelo, Pablo; Almany, Glenn R; Berumen, Michael L; Thorrold, Simon R; Jones, Geoffrey P; Planes, Serge

2015-11-22

Determining the conditions under which populations may persist requires accurate estimates of demographic parameters, including immigration, local reproductive success, and mortality rates. In marine populations, empirical estimates of these parameters are rare, due at least in part to the pelagic dispersal stage common to most marine organisms. Here, we evaluate population persistence and turnover for a population of orange clownfish, Amphiprion percula, at Kimbe Island in Papua New Guinea. All fish in the population were sampled and genotyped on five occasions at 2-year intervals spanning eight years. The genetic data enabled estimates of reproductive success retained in the same population (reproductive success to self-recruitment), reproductive success exported to other subpopulations (reproductive success to local connectivity), and immigration and mortality rates of sub-adults and adults. Approximately 50% of the recruits were assigned to parents from the Kimbe Island population and this was stable through the sampling period. Stability in the proportion of local and immigrant settlers is likely due to: low annual mortality rates and stable egg production rates, and the short larval stages and sensory capacities of reef fish larvae. Biannual mortality rates ranged from 0.09 to 0.55 and varied significantly spatially. We used these data to parametrize a model that estimated the probability of the Kimbe Island population persisting in the absence of immigration. The Kimbe Island population was found to persist without significant immigration. Model results suggest the island population persists because the largest of the subpopulations are maintained due to having low mortality and high self-recruitment rates. Our results enable managers to appropriately target and scale actions to maximize persistence likelihood as disturbance frequencies increase. © 2015 The Author(s).

Importance of benthic production to fish populations in Lake Mead prior to the establishment of quagga mussels

USGS Publications Warehouse

Umek, John; Chandra, Sudeep; Rosen, Michael; Wittmann, Marion; Sullivan, Joe; Orsak, Erik

2010-01-01

Limnologists recently have developed an interest in quantifying benthic resource contributions to higher-level consumers. Much of this research focuses on natural lakes with very little research in reservoirs. In this study, we provide a contemporary snapshot of the food web structure of Lake Mead to evaluate the contribution of benthic resources to fish consumers. In addition, we document the available food to fishes on soft sediments and changes to the invertebrate community over 2 time periods. Benthic invertebrate food availability for fishes is greater in Las Vegas Bay than Overton Arm. Las Vegas Bay is dominated by oligochaetes, whose biomass increased with depth, while Overton Arm is dominated by chironomids, whose biomass did not change with depth. Diet and isotopic measurements indicate the fish community largely relies on benthic resources regardless of basin (Las Vegas Bay >80%; Overton Arm >92%); however, the threadfin shad likely contribute more to largemouth and striped bass production in Overton Arm versus Las Vegas Bay. A 2-time period analysis, pre and post quagga mussel establishment and during lake level declines, suggests there is no change in the density of benthic invertebrates in Boulder Basin, but there were greater abundances of select taxa in this basin by season and depth than in other basins. Given the potential of alterations as a result of the expansion of quagga mussel and the reliance of the fishery on benthic resources, future investigation of basin specific, benthic processes is recommended.

Effects of stream acidification and habitat on fish populations of a North American river

USGS Publications Warehouse

Baldigo, Barry P.; Lawrence, G.B.

2001-01-01

Water quality, physical habitat, and fisheries at sixteen reaches in the Neversink River Basin were studied during 1991-95 to identify the effects of acidic precipitation on stream-water chemistry and on selected fish-species populations, and to test the hypothesis that the degree of stream acidification affected the spatial distribution of each fish-species population. Most sites on the East Branch Neversink were strongly to severely acidified, whereas most sites on the West Branch were minimally to moderately acidified. Mean density of fish populations ranged from 0 to 2.15 fish/m2; biomass ranged from 0 to 17.5 g/m2. Where brook trout were present, their population density ranged from 0.04 to 1.09 fish/m2, biomass ranged from 0.76 to 12.2 g/m2, and condition (K) ranged from 0.94 to 1.07. Regression analyses revealed strong relations (r2 ?? 0.41 to 0.99; p ??? 0.05) between characteristics of the two most common species (brook trout and slimy sculpin) populations and mean concentrations of inorganic monomeric aluminum (Alim), pH, Si, K+, NO3/-, NH4/+, DOC, Ca2+, and Na+; acid neutralizing capacity (ANC); and water temperature. Stream acidification may have adversely affected fish populations at most East Branch sites, but in other parts of the Neversink River Basin these effects were masked or mitigated by other physical habitat, geochemical, and biological factors.

Management of fish populations in large rivers: a review of tools and approaches

USGS Publications Warehouse

Petts, Geoffrey E.; Imhoff, Jack G.; Manny, Bruce A.; Maher, John F. B.; Weisberg, Stephen B.

1989-01-01

In common with most branches of science, the management of riverine fish populations is characterised by reductionist and isolationist philosophies. Traditional fish management focuses on stocking and controls on fishing. This paper presents a concensus of scientists involved in the LARS workshop on the management of fish populations in large rivers. A move towards a more holistic philosophy is advocated, with fish management forming an integral part of sustainable river development. Based upon a questionnaire survey of LARS members, with wide-ranging expertise and experience from all parts of the world, lists of management tools currently in use are presented. Four categories of tools are described: flow, water-quality, habitat, and biological. The potential applications of tools for fish management in large rivers is discussed and research needs are identified. The lack of scientific evaluations of the different tools remains the major constraint to their wider application.

Assessing three fish species ecological status in Colorado River, Grand Canyon based on physical habitat and population models.

PubMed

Yao, Weiwei; Chen, Yuansheng

2018-04-01

Colorado River is a unique ecosystem and provides important ecological services such as habitat for fish species as well as water power energy supplies. River management for this ecosystem requires assessment and decision support tools for fish which involves protecting, restoring as well as forecasting of future conditions. In this paper, a habitat and population model was developed and used to determine the levels of fish habitat suitability and population density in Colorado River between Lees Ferry and Lake Mead. The short term target fish populations are also predicted based on native fish recovery strategy. This model has been developed by combining hydrodynamics, heat transfer and sediment transport models with a habitat suitability index model and then coupling with habitat model into life stage population model. The fish were divided into four life stages according to the fish length. Three most abundant and typical native and non-native fish were selected as target species, which are rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and flannelmouth sucker (Catostomus latipinnis). Flow velocity, water depth, water temperature and substrates were used as the suitability indicators in habitat model and overall suitability index (OSI) as well as weight usable area (WUA) was used as an indicator in population model. A comparison was made between simulated fish population alteration and surveyed fish number fluctuation during 2000 to 2009. The application of this habitat and population model indicates that this model can be accurate present habitat situation and targets fish population dynamics of in the study areas. The analysis also indicates the flannelmouth sucker population will steadily increase while the rainbow trout will decrease based on the native fish recovery scheme. Copyright © 2018. Published by Elsevier Inc.

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.

Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

PubMed Central

Johnson, Andrew C.; Sumpter, John P.

2014-01-01

The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s–1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure. PMID:25405969

Report A: Fish distribution and population dynamics in Rock Creek, Klickitat County, Washington

USGS Publications Warehouse

Allen, Brady; Munz, Carrie S.; Harvey, Elaine

2013-01-01

The U.S. Geological Survey collaborated with the Yakama Nation starting in fall of 2009 to study the fish populations in Rock Creek, a Washington State tributary of the Columbia River 21 kilometers upstream of John Day Dam. Prior to this study, very little was known about the ESA-listed (threatened) Mid-Columbia River steelhead (Oncorhynchus mykiss) population in this arid watershed with intermittent stream flow. The objectives of the study were to quantify fish habitat, document fish distribution, abundance, and movement, and identify areas of high salmonid productivity. To accomplish these objectives, we electrofished in the spring and fall, documenting the distribution and relative abundance of all fish species to evaluate the influence of biotic factors on salmonid productivity and survival. We surveyed the distribution of perennial pools and established a network of automated temperature recording devices from river kilometer (rkm) 2 to 23 in Rock Creek and rkm 0 to 8 in Squaw Creek, a major tributary entering Rock Creek at rkm 13, to better understand the abiotic factors influencing the salmonid populations. Salmonid abundance estimates were conducted using a mark-recapture method in a systematic subsample of the perennial pools. The proportion and timing of salmonids migrating from these pools were assessed by building, installing, and operating two passive integrated transponder (PIT) tag interrogation systems at rkm 5 and at the confluence with Squaw Creek (rkm 13). From fall 2009 to fall 2012, we PIT-tagged 3,088 O. mykiss and 151 coho salmon (O. kisutch) during electrofishing efforts. In the lowest flow periods of 2010 to 2012, we found that an average of 36% of the surveyed streambed length was dry, and 17% remained as perennial pools. The maximum temperature recorded in those pools was 24.4°C, but most pools had a maximum temperature that was less than 21°C. O. mykiss were present in most pools, and non-native fish species, such as smallmouth bass

Fishery-independent data reveal negative effect of human population density on Caribbean predatory fish communities.

PubMed

Stallings, Christopher D

2009-01-01

Understanding the current status of predatory fish communities, and the effects fishing has on them, is vitally important information for management. However, data are often insufficient at region-wide scales to assess the effects of extraction in coral reef ecosystems of developing nations. Here, I overcome this difficulty by using a publicly accessible, fisheries-independent database to provide a broad scale, comprehensive analysis of human impacts on predatory reef fish communities across the greater Caribbean region. Specifically, this study analyzed presence and diversity of predatory reef fishes over a gradient of human population density. Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species. Complete disappearance of several large-bodied fishes indicates ecological and local extinctions have occurred in some densely populated areas. These findings fill a fundamentally important gap in our knowledge of the ecosystem effects of artisanal fisheries in developing nations, and provide support for multiple approaches to data collection where they are commonly unavailable.

Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities

PubMed Central

Stallings, Christopher D.

2009-01-01

Background Understanding the current status of predatory fish communities, and the effects fishing has on them, is vitally important information for management. However, data are often insufficient at region-wide scales to assess the effects of extraction in coral reef ecosystems of developing nations. Methodology/Principal Findings Here, I overcome this difficulty by using a publicly accessible, fisheries-independent database to provide a broad scale, comprehensive analysis of human impacts on predatory reef fish communities across the greater Caribbean region. Specifically, this study analyzed presence and diversity of predatory reef fishes over a gradient of human population density. Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species. Conclusions/Significance Complete disappearance of several large-bodied fishes indicates ecological and local extinctions have occurred in some densely populated areas. These findings fill a fundamentally important gap in our knowledge of the ecosystem effects of artisanal fisheries in developing nations, and provide support for multiple approaches to data collection where they are commonly unavailable. PMID:19421312

Fish abundance and population stability in a reservoir tailwater and an unregulated headwater stream

USGS Publications Warehouse

Jacobs, K.E.; Swink, W.D.

1983-01-01

Fish abundance and population stability were compared in the tailwater and in an unregulated tributary of Barren River Lake, a flood control reservoir in south central Kentucky. Fish abundance was greater in the tailwater near the dam and was dominated by three species common in the reservoir: gizzard shad (Dorosoma cepedianum), bluegills (Lepomis macrochirus), and white crappies (Pomoxis annularis). Three riverine suckers were less abundant in the tailwater than in the unregulated stream: northern hog suckers (Hypentelium nigricans), black redhorse (Moxostoma duquesnei), and golden redhorse (Moxostoma erythrurum). The fish populations in the tailwater, particularly common carp (Cyprinus carpio), northern hog suckers, black redhorse, and golden redhorse, were less stable than those in the unregulated stream. Population stability is defined as the extent to which fish remain in a stream section. This study suggests that the occurrence of reservoir species in the tailwater was the result of fish passage from the reservoir during high discharges in fall and winter. Reservoir operations (altered flow, low summer water temperature, and poor summer water quality) probably were responsible for the unstable populations of common carp and riverine suckers in the tailwater.

Importance of the habitat choice behavior assumed when modeling the effects of food and temperature on fish populations

USGS Publications Warehouse

Wildhaber, Mark L.; Lamberson, Peter J.

2004-01-01

Various mechanisms of habitat choice in fishes based on food and/or temperature have been proposed: optimal foraging for food alone; behavioral thermoregulation for temperature alone; and behavioral energetics and discounted matching for food and temperature combined. Along with development of habitat choice mechanisms, there has been a major push to develop and apply to fish populations individual-based models that incorporate various forms of these mechanisms. However, it is not known how the wide variation in observed and hypothesized mechanisms of fish habitat choice could alter fish population predictions (e.g. growth, size distributions, etc.). We used spatially explicit, individual-based modeling to compare predicted fish populations using different submodels of patch choice behavior under various food and temperature distributions. We compared predicted growth, temperature experience, food consumption, and final spatial distribution using the different models. Our results demonstrated that the habitat choice mechanism assumed in fish population modeling simulations was critical to predictions of fish distribution and growth rates. Hence, resource managers who use modeling results to predict fish population trends should be very aware of and understand the underlying patch choice mechanisms used in their models to assure that those mechanisms correctly represent the fish populations being modeled.

Habitat fragmentation caused by contaminants: Atrazine as a chemical barrier isolating fish populations.

PubMed

Araújo, Cristiano V M; Silva, Daniel C V R; Gomes, Luiz E T; Acayaba, Raphael D; Montagner, Cassiana C; Moreira-Santos, Matilde; Ribeiro, Rui; Pompêo, Marcelo L M

2018-02-01

Information on how atrazine can affect the spatial distribution of organisms is non-existent. As this effect has been observed for some other contaminants, we hypothesized that atrazine-containing leachates/discharges could trigger spatial avoidance by the fish Poecilia reticulata and form a chemical barrier isolating upstream and downstream populations. Firstly, guppies were exposed to an atrazine gradient in a non-forced exposure system, in which organisms moved freely among the concentrations, to assess their ability to avoid atrazine. Secondly, a chemical barrier formed by atrazine, separating two clean habitats (extremities of the non-forced system), was simulated to assess whether the presence of the contaminant could prevent guppies from migrating to the other side of the system. Fish were able to avoid atrazine contamination at environmentally relevant concentrations (0.02 μg L -1 ), below those described to cause sub-lethal effects. The AC 50 (atrazine concentration causing avoidance to 50% of the population) was 0.065 μg L -1 . The chemical barrier formed by atrazine at 150 μg L -1 (concentration that should produce an avoidance around 82%) caused a reduction in the migratory potential of the fish by 47%; while the chemical barrier at 1058 μg L -1 (concentration that produces torpidity) caused a reduction in the migratory potential of the fish by 91%. Contamination by atrazine, besides driving the spatial distribution of fish populations, has potential to act as a chemical barrier by isolating fish populations. This study includes a novel approach to be integrated in environmental risk assessment schemes to assess high-tier contamination effects such as habitat fragmentation and population displacement and isolation. Copyright © 2017 Elsevier Ltd. All rights reserved.

COST AND BENEFITS OF ALTERED BENZO(A)PYRENE METABOLISM IN A PCB-ADAPTED FISH POPULATION

EPA Science Inventory

We examined populations of an estuarine fish species (Fundulus heteroclitus) resident to a highly contaminated site and a reference site for their ability to metabolize an important environmental pollutant. In previous work, we characterized the fish population resident to this h...

Vicariance and dispersal across Baja California in disjunct marine fish populations.

PubMed

Bernardi, Giacomo; Findley, Lloyd; Rocha-Olivares, Axayacatl

2003-07-01

Population disjunctions, as a first step toward complete allopatry, present an interesting situation to study incipient speciation. The geological formation of the Baja California Peninsula currently divides 19 species of fish into disjunct populations that are found on its Pacific Coast and in the northern part of the Gulf of California (also called the Sea of Cortez), but are absent from the Cape (Cabo San Lucas) region. We studied the genetic makeup of disjunct populations for 12 of these 19 fish species. Phylogeographic patterns for the 12 species can be separated into two major classes: a first group (eight species) showed reciprocal monophyly and high genetic divergence between disjunct populations. A second group (four species) displayed what appeared to be panmictic populations. Population structure between Pacific Coast populations, across the Punta Eugenia biogeographic boundary, was also evaluated. While dispersal potential (inferred by pelagic larval duration) was a poor predictor of population structure between Gulf of California and Pacific populations, we found that population genetic subdivision along the Pacific Coast at Punta Eugenia was always positively correlated with differentiation between Pacific and Gulf of California populations. Vicariant events, ongoing gene flow, and ecological characteristics played essential roles in shaping the population structures observed in this study.

Pathogens associated with native and exotic trout populations in Shenandoah National Park and the relationships to fish stocking practices

USGS Publications Warehouse

Panek, Frank M.; Atkinson, James; Coll, John

2008-01-01

Restrictive fish stocking policies in National Parks were developed as early as 1936 in order to preserve native fish assemblages and historic genetic diversity. Despite recent efforts to understand the effects of non-native or exotic fish introductions, park managers have limited information regarding the effects of these introductions on native fish communities. Shenandoah National Park was established in 1936 and brook trout (Salvelinus fontinalis) restoration within selected streams in the park began in 1937 in collaboration with the Virginia Department of Game and Inland Fisheries (VDGIF). An analysis of tissue samples from brook, brown (Salmo trutta), and rainbow trout (Oncorhynchus mykiss) from 29 streams within the park from 1998–2002 revealed the presence of Renibacterium salmoninarum, Yersinia ruckeri, and infectious pancreatic necrosis virus (IPNv). In order to investigate the relationships of the occurrence of fish pathogens with stocking histories we classified the streams into three categories: 1) streams with no record of stocking, 2) streams that are known to have been stocked historically, and 3) streams that were historically stocked within the park and continue to be stocked downstream of the park boundary. The occurrences of pathogens were summarized relative to this stocking history. Renibacterium salmoninarum, the causative agent of bacterial kidney disease, was the most prevalent pathogen found, occurring in all three species and stream stocking categories, and appears to be endemic to the park. Two other pathogens, Yersinia ruckeri and infectious pancreatic necrosis virus were also described from brook trout populations within the park. IPNv was only found in brook trout populations in streams with prior stocking histories. Yersinia ruckeri was only found in brook trout in steams that have never been stocked and like R. salmoninarum, is likely endemic.

A cautionary note on Bayesian estimation of population size by removal sampling with diffuse priors.

PubMed

Bord, Séverine; Bioche, Christèle; Druilhet, Pierre

2018-05-01

We consider the problem of estimating a population size by removal sampling when the sampling rate is unknown. Bayesian methods are now widespread and allow to include prior knowledge in the analysis. However, we show that Bayes estimates based on default improper priors lead to improper posteriors or infinite estimates. Similarly, weakly informative priors give unstable estimators that are sensitive to the choice of hyperparameters. By examining the likelihood, we show that population size estimates can be stabilized by penalizing small values of the sampling rate or large value of the population size. Based on theoretical results and simulation studies, we propose some recommendations on the choice of the prior. Then, we applied our results to real datasets. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sea lice and salmon population dynamics: effects of exposure time for migratory fish.

PubMed

Krkosek, Martin; Morton, Alexandra; Volpe, John P; Lewis, Mark A

2009-08-07

The ecological impact of parasite transmission from fish farms is probably mediated by the migration of wild fishes, which determines the period of exposure to parasites. For Pacific salmon and the parasitic sea louse, Lepeophtheirus salmonis, analysis of the exposure period may resolve conflicting observations of epizootic mortality in field studies and parasite rejection in experiments. This is because exposure periods can differ by 2-3 orders of magnitude, ranging from months in the field to hours in experiments. We developed a mathematical model of salmon-louse population dynamics, parametrized by a study that monitored naturally infected juvenile salmon held in ocean enclosures. Analysis of replicated trials indicates that lice suffer high mortality, particularly during pre-adult stages. The model suggests louse populations rapidly decline following brief exposure of juvenile salmon, similar to laboratory study designs and data. However, when the exposure period lasts for several weeks, as occurs when juvenile salmon migrate past salmon farms, the model predicts that lice accumulate to abundances that can elevate salmon mortality and depress salmon populations. The duration of parasite exposure is probably critical to salmon-louse population dynamics, and should therefore be accommodated in coastal planning and management where fish farms are situated on wild fish migration routes.

Effects of Spearfishing on Reef Fish Populations in a Multi-Use Conservation Area

PubMed Central

Frisch, Ashley J.; Cole, Andrew J.; Hobbs, Jean-Paul A.; Rizzari, Justin R.; Munkres, Katherine P.

2012-01-01

Although spearfishing is a popular method of capturing fish, its ecological effects on fish populations are poorly understood, which makes it difficult to assess the legitimacy and desirability of spearfishing in multi-use marine reserves. Recent management changes within the Great Barrier Reef Marine Park (GBRMP) fortuitously created a unique scenario by which to quantify the effects of spearfishing on fish populations. As such, we employed underwater visual surveys and a before-after-control-impact experimental design to investigate the effects of spearfishing on the density and size structure of target and non-target fishes in a multi-use conservation park zone (CPZ) within the GBRMP. Three years after spearfishing was first allowed in the CPZ, there was a 54% reduction in density and a 27% reduction in mean size of coral trout (Plectropomus spp.), the primary target species. These changes were attributed to spearfishing because benthic habitat characteristics and the density of non-target fishes were stable through time, and the density and mean size of coral trout in a nearby control zone (where spearfishing was prohibited) remained unchanged. We conclude that spearfishing, like other forms of fishing, can have rapid and substantial negative effects on target fish populations. Careful management of spearfishing is therefore needed to ensure that conservation obligations are achieved and that fishery resources are harvested sustainably. This is particularly important both for the GBRMP, due to its extraordinarily high conservation value and world heritage status, and for tropical island nations where people depend on spearfishing for food and income. To minimize the effects of spearfishing on target species and to enhance protection of functionally important fishes (herbivores), we recommend that fishery managers adjust output controls such as size- and catch-limits, rather than prohibit spearfishing altogether. This will preserve the cultural and social

Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate.

PubMed

Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

2015-06-01

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal.

Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate

PubMed Central

Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

2015-01-01

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal. PMID:26078856

Discrimination of fish populations using parasites: Random Forests on a 'predictable' host-parasite system.

PubMed

Pérez-Del-Olmo, A; Montero, F E; Fernández, M; Barrett, J; Raga, J A; Kostadinova, A

2010-10-01

We address the effect of spatial scale and temporal variation on model generality when forming predictive models for fish assignment using a new data mining approach, Random Forests (RF), to variable biological markers (parasite community data). Models were implemented for a fish host-parasite system sampled along the Mediterranean and Atlantic coasts of Spain and were validated using independent datasets. We considered 2 basic classification problems in evaluating the importance of variations in parasite infracommunities for assignment of individual fish to their populations of origin: multiclass (2-5 population models, using 2 seasonal replicates from each of the populations) and 2-class task (using 4 seasonal replicates from 1 Atlantic and 1 Mediterranean population each). The main results are that (i) RF are well suited for multiclass population assignment using parasite communities in non-migratory fish; (ii) RF provide an efficient means for model cross-validation on the baseline data and this allows sample size limitations in parasite tag studies to be tackled effectively; (iii) the performance of RF is dependent on the complexity and spatial extent/configuration of the problem; and (iv) the development of predictive models is strongly influenced by seasonal change and this stresses the importance of both temporal replication and model validation in parasite tagging studies.

Length-Based Assessment of Coral Reef Fish Populations in the Main and Northwestern Hawaiian Islands

PubMed Central

Nadon, Marc O.; Ault, Jerald S.; Williams, Ivor D.; Smith, Steven G.; DiNardo, Gerard T.

2015-01-01

The coral reef fish community of Hawaii is composed of hundreds of species, supports a multimillion dollar fishing and tourism industry, and is of great cultural importance to the local population. However, a major stock assessment of Hawaiian coral reef fish populations has not yet been conducted. Here we used the robust indicator variable “average length in the exploited phase of the population (L¯)”, estimated from size composition data from commercial fisheries trip reports and fishery-independent diver surveys, to evaluate exploitation rates for 19 Hawaiian reef fishes. By and large, the average lengths obtained from diver surveys agreed well with those from commercial data. We used the estimated exploitation rates coupled with life history parameters synthesized from the literature to parameterize a numerical population model and generate stock sustainability metrics such as spawning potential ratios (SPR). We found good agreement between predicted average lengths in an unfished population (from our population model) and those observed from diver surveys in the largely unexploited Northwestern Hawaiian Islands. Of 19 exploited reef fish species assessed in the main Hawaiian Islands, 9 had SPRs close to or below the 30% overfishing threshold. In general, longer-lived species such as surgeonfishes, the redlip parrotfish (Scarus rubroviolaceus), and the gray snapper (Aprion virescens) had the lowest SPRs, while short-lived species such as goatfishes and jacks, as well as two invasive species (Lutjanus kasmira and Cephalopholis argus), had SPRs above the 30% threshold. PMID:26267473

Native fishes in the Truckee River: Are in-stream structures and patterns of population genetic structure related?

PubMed

Peacock, Mary M; Gustin, Mae S; Kirchoff, Veronica S; Robinson, Morgan L; Hekkala, Evon; Pizzarro-Barraza, Claudia; Loux, Tim

2016-09-01

In-stream structures are recognized as significant impediments to movement for freshwater fishes. Apex predators such as salmonids have been the focus of much research on the impacts of such barriers to population dynamics and population viability however much less research has focused on native fishes, where in-stream structures may have a greater impact on long term population viability of these smaller, less mobile species. Patterns of genetic structure on a riverscape can provide information on which structures represent real barriers to movement for fish species and under what specific flow conditions. Here we characterize the impact of 41 dam and diversion structures on movement dynamics under varying flow conditions for a suite of six native fishes found in the Truckee River of California and Nevada. Microsatellite loci were used to estimate total allelic diversity, effective population size and assess genetic population structure. Although there is spatial overlap among species within the river there are clear differences in species distributions within the watershed. Observed population genetic structure was associated with in-stream structures, but only under low flow conditions. High total discharge in 2006 allowed fish to move over potential barriers resulting in no observed population genetic structure for any species in 2007. The efficacy of in-stream structures to impede movement and isolate fish emerged only after multiple years of low flow conditions. Our results suggest that restricted movement of fish species, as a result of in-stream barriers, can be mitigated by flow management. However, as flow dynamics are likely to be altered under global climate change, fragmentation due to barriers could isolate stream fishes into small subpopulations susceptible to both demographic losses and losses of genetic variation. Copyright © 2016 Elsevier B.V. All rights reserved.

Sex change and effective population size: implications for population genetic studies in marine fish.

PubMed

Coscia, I; Chopelet, J; Waples, R S; Mann, B Q; Mariani, S

2016-10-01

Large variance in reproductive success is the primary factor that reduces effective population size (Ne) in natural populations. In sequentially hermaphroditic (sex-changing) fish, the sex ratio is typically skewed and biased towards the 'first' sex, while reproductive success increases considerably after sex change. Therefore, sex-changing fish populations are theoretically expected to have lower Ne than gonochorists (separate sexes), assuming all other parameters are essentially equal. In this study, we estimate Ne from genetic data collected from two ecologically similar species living along the eastern coast of South Africa: one gonochoristic, the 'santer' sea bream Cheimerius nufar, and one protogynous (female-first) sex changer, the 'slinger' sea bream Chrysoblephus puniceus. For both species, no evidence of genetic structuring, nor significant variation in genetic diversity, was found in the study area. Estimates of contemporary Ne were significantly lower in the protogynous species, but the same pattern was not apparent over historical timescales. Overall, our results show that sequential hermaphroditism may affect Ne differently over varying time frames, and that demographic signatures inferred from genetic markers with different inheritance modes also need to be interpreted cautiously, in relation to sex-changing life histories.

Eye fluke-induced cataracts in natural fish populations: is there potential for host manipulation?

PubMed

Seppälä, O; Karvonen, A; Valtonen, E T

2011-02-01

Manipulation of host phenotype (e.g. behaviour, appearance) is suggested to be a common strategy to enhance transmission in trophically transmitted parasites. However, in many systems, evidence of manipulation comes exclusively from laboratory studies and its occurrence in natural host populations is poorly understood. Here, we examined the potential for host manipulation by Diplostomum eye flukes indirectly by quantifying the physiological effects of parasites on fish. Earlier laboratory studies have shown that Diplostomum infection predisposes fish to predation by birds (definitive hosts of the parasites) by reducing fish vision through cataract formation. However, occurrence of cataracts and the subsequent potential for host manipulation in natural fish populations has remained poorly explored. We studied the occurrence of eye fluke-induced cataracts from 7 common fish species (Gymnocephalus cernuus, Rutilus rutilus, Leuciscus leuciscus, Alburnus alburnus, Osmerus eperlanus, Coregonus lavaretus and Gasterosteus aculeatus) from the Bothnian Bay in the Baltic Sea. We found that the parasite-induced cataracts were common in fish and they also reached high levels which are likely to predispose fish to predation. However, we observed such cataracts only in species with the highest parasite abundances, which suggests that only certain hosts may be strongly affected by the infection.

Response of fish population dynamics to mitigation activities in a large regulated river

USGS Publications Warehouse

Watkins, Carson J.; Ross, Tyler J.; Quist, Michael C.; Hardy, Ryan S.

2017-01-01

Extensive water development in large rivers has precipitated many negative ecological effects on native fish populations. Mitigation for such development often focuses on restoring biological integrity through remediation of the physical and chemical properties of regulated rivers. However, evaluating and defining the success of those programs can be difficult. We modeled the influence of mitigation-related environmental factors on growth and recruitment of two ecologically important native fish species (Largescale Sucker Catostomus macrocheilus and Mountain Whitefish Prosopium williamsoni) in the Kootenai River, Idaho. Artificial nutrient (phosphorus) addition best predicted the variability in annual growth of both species. Nutrient addition was positively related to Largescale Sucker growth but negatively related to Mountain Whitefish growth. The best model explained 82% of the annual variability in incremental growth for Largescale Suckers and 61% of the annual variability for Mountain Whitefish. Year-class strength of Largescale Suckers was not closely related to any of the environmental variables evaluated; however, year-class strength of Mountain Whitefish was closely associated with nutrient addition, discharge, and temperature. Most research has focused on biotic assemblages to evaluate the effects of mitigation activities on fishes, but there is an increased need to identify the influence of rehabilitation activities on fish population dynamics within those assemblages. Here, we demonstrate how fish growth can serve as an indicator of rehabilitation success in a highly regulated large river. Future fish restoration projects can likely benefit from a change in scope and from consideration of an evaluation framework involving the response of population rate functions to mitigation.

Removal of nonnative fish results in population expansion of a declining amphibian (mountain yellow-legged frog, Rana muscosa)

PubMed Central

KNAPP, Roland A.; BOIANO, Daniel M.; VREDENBURG, Vance T.

2007-01-01

The mountain yellow-legged frog (Rana muscosa) was once a common inhabitant of the Sierra Nevada (California, USA), but has declined precipitously during the past century due in part to the introduction of nonnative fish into naturally fishless habitats. The objectives of the current study were to describe (1) the effect of fish removal from three lakes (located in two watersheds) on the small, remnant R. muscosa populations inhabiting those lakes, and (2) the initial development of metapopulation structure in each watershed as R. muscosa from expanding populations in fish-removal lakes dispersed to adjacent habitats. At all three fish-removal lakes, R. muscosa population densities increased significantly following the removal of predatory fish. The magnitude of these increases was significantly greater than that observed over the same time period in R. muscosa populations inhabiting control lakes that remained in their natural fishless condition. Following these population increases, R. muscosa dispersed to adjacent suitable (but unoccupied) sites, moving between 200 and 900 m along streams or across dry land. Together, these results suggest that large-scale removal of introduced fish could result in at least partial reversal of the decline of R. muscosa. Continued monitoring of R. muscosa at the fish-removal sites will be necessary to determine whether the positive effects of fish eradication are sustained over the long-term, especially in light of the increasingly important role played by an emerging infectious disease (chytridiomycosis, caused by Batrachochytrium dendrobatidis) in influencing R. muscosa populations. PMID:17396156

Proposed methods and endpoints for defining and assessing adverse environmental impact (AEI) on fish communities/populations in Tennessee River reservoirs.

PubMed

Hickman, Gary D; Brown, Mary L

2002-06-07

Two multimetric indices have been developed to help address fish community (reservoir fish assemblage index [RFAI]) and individual population quality (sport fishing index [SFI]) in Tennessee River reservoirs. The RFAI, with characteristics similar to the index of biotic integrity (IBI) used in stream fish community determinations, was developed to monitor the existing condition of resident fish communities. The index, which incorporates standardized electrofishing of littoral areas and experimental gill netting for limnetic bottom-dwelling species, has been used to determine residential fish community response to various anthropogenic impacts in southeastern reservoirs. The SFI is a multimetric index designed to address the quality of the fishery for individual resident sport fish species in a particular lake or reservoir[4]. The SFI incorporates measures of fish population aspects and angler catch and pressure estimates. This paper proposes 70% of the maximum RFAI score and 10% above the average SFI score for individual species as "screening" endpoints for balanced indigenous populations (BIP) or adverse environmental impact (AEI). Endpoints for these indices indicate: (1) communities/populations are obviously balanced indigenous populations (BIP) indicating no adverse environmental impact (AEI), or are "screened out"; (2) communities/populations are considered to be potentially impacted; and (3) where the resident fish community/population should be considered adversely impacted. Suggestions are also made concerning how examination of individual metric scores can help determine the source or cause of the impact.

Fish population studies using parasites from the Southeastern Pacific Ocean: considering host population changes and species body size as sources of variability of parasite communities.

PubMed

George-Nascimento, Mario; Oliva, Marcelo

2015-01-01

Research using parasites in fish population studies in the South Eastern Pacific (SEP) is summarized. There are 27 such studies (snapshots mainly) in single host species sampled at different geographic localities and at somewhat similar times. They have been devoted mainly to economically important species, though others on coastal and intertidal fish or on less- or non-commercial species provide insights on scales of temporal and spatial variation of parasite infracommunities. Later, we assess whether the probability of harbouring parasites depends on the host species body size. Our results indicate that a stronger tool for fish population studies may be developed under regular (long term) scrutiny of parasite communities, especially of small fish host species, due to their larger variability in richness, abundance and total biomass, than in large fish species. Finally, it might also be necessary to consider the effects of fishing on parasite communities as well as the natural oscillations (coupled or not) of host and parasite populations.

An empirical model for estimating annual consumption by freshwater fish populations

USGS Publications Warehouse

Liao, H.; Pierce, C.L.; Larscheid, J.G.

2005-01-01

Population consumption is an important process linking predator populations to their prey resources. Simple tools are needed to enable fisheries managers to estimate population consumption. We assembled 74 individual estimates of annual consumption by freshwater fish populations and their mean annual population size, 41 of which also included estimates of mean annual biomass. The data set included 14 freshwater fish species from 10 different bodies of water. From this data set we developed two simple linear regression models predicting annual population consumption. Log-transformed population size explained 94% of the variation in log-transformed annual population consumption. Log-transformed biomass explained 98% of the variation in log-transformed annual population consumption. We quantified the accuracy of our regressions and three alternative consumption models as the mean percent difference from observed (bioenergetics-derived) estimates in a test data set. Predictions from our population-size regression matched observed consumption estimates poorly (mean percent difference = 222%). Predictions from our biomass regression matched observed consumption reasonably well (mean percent difference = 24%). The biomass regression was superior to an alternative model, similar in complexity, and comparable to two alternative models that were more complex and difficult to apply. Our biomass regression model, log10(consumption) = 0.5442 + 0.9962??log10(biomass), will be a useful tool for fishery managers, enabling them to make reasonably accurate annual population consumption predictions from mean annual biomass estimates. ?? Copyright by the American Fisheries Society 2005.

Basinwide Estimation of Habitat and Fish Populations in Streams

Treesearch

C. Andrew Dolloff; David G. Hankin; Gordon H. Reeves

1993-01-01

Basinwide visual estimation techniques (BVET) are statistically reliable and cost effective for estimating habitat and fish populations across entire watersheds. Survey teams visit habitats in every reach of the study area to record visual observations. At preselected intervals, teams also record actual measurements. These observations and measurements are used to...

Trematode infection causes malformations and population effects in a declining New Zealand fish.

PubMed

Kelly, David W; Thomas, Harriet; Thieltges, David W; Poulin, Robert; Tompkins, Daniel M

2010-03-01

1. Animal malformations engender wide public and scientific concern because of associated environmental health risks. This is highlighted by increased incidence of limb malformations in amphibians associated with trematode infections and disturbance. Malformations may signal new emerging disease threats, but whether the phenomenon is broadly applicable across taxa, or has population-scale impacts, is unknown. 2. Malformations are widely reported in fish and, until now, have been attributed mainly to contaminants. We tested whether the trematode Telogaster opisthorchis caused severe malformations, leading to population effects, in Galaxias anomalus, a threatened New Zealand freshwater fish. 3. Experimental infection of larval fish caused increasing spinal malformation and mortality with infection intensity that closely matched field patterns. Field malformation frequency peaked in January (65%), before declining sharply in February (25%) and remaining low thereafter. 4. The peak occurred during a 'critical window' of larval development, with the decline coincident with a population crash, indicating that malformation was causing mortality in the field. 5. The occurrence of such critical developmental windows may explain why this mechanism of population impact has been overlooked. With global environmental stressors predicted to enhance trematode infections, our results show that parasite-induced malformation, and its population-scale impacts, could be more widespread than previously considered.

Evaluation of Fluoride Retention Due to Most Commonly Consumed Estuarine Fishes Among Fish Consuming Population of Andhra Pradesh as a Contributing Factor to Dental Fluorosis: A Cross-Sectional Study

PubMed Central

Ganta, Shravani; Nagaraj, Anup; Pareek, Sonia; Sidiq, Mohsin; Singh, Kushpal; Vishnani, Preeti

2015-01-01

Background Fluoride in drinking water is known for both beneficial and detrimental effects on health. The principal sources of fluoride include water, some species of vegetation, certain edible marine animals, dust and industrial processes. The purpose of this study was to evaluate the fluoride retention of most commonly consumed estuarine fishes among fish consuming population of Andhra Pradesh. Materials and Methods A cross-sectional study was conducted to evaluate the amount of fluoride retention due to ten most commonly consumed estuarine fishes as a contributing factor to Fluorosis by SPADNS Spectrophotometric method. The presence and severity of dental fluorosis among fish consuming population was recorded using Community Fluorosis Index. Statistical analysis was done using MedCalc v12.2.1.0 software. Results For Sea water fishes, the fluoride levels in bone were maximum in Indian Sardine (4.22 ppm). Amongst the river water fishes, the fluoride levels in bone were maximum in Catla (1.51 ppm). Also, the mean total fluoride concentrations of all the river fishes in skin, muscle and bone were less (0.86 ppm) as compared to the sea water fishes (2.59 ppm). It was unveiled that sea fishes accumulate relatively large amounts of Fluoride as compared to the river water fishes. The mean Community Fluorosis Index was found to be 1.06 amongst a sampled fish consuming population. Evaluation by Community Index for Dental fluorosis (CFI) suggested that fluorosis is of medium public health importance. Conclusion It was analysed that bone tends to accumulate more amount of fluoride followed by muscle and skin which might be due to the increased permeability and chemical trapping of fluoride inside the tissues. The amount of fluoride present in the fishes is directly related to the severity of fluorosis amongst fish consuming population, suggesting fishes as a contributing factor to fluorosis depending upon the dietary consumption. PMID:26266208

Evaluation of Fluoride Retention Due to Most Commonly Consumed Estuarine Fishes Among Fish Consuming Population of Andhra Pradesh as a Contributing Factor to Dental Fluorosis: A Cross-Sectional Study.

PubMed

Ganta, Shravani; Yousuf, Asif; Nagaraj, Anup; Pareek, Sonia; Sidiq, Mohsin; Singh, Kushpal; Vishnani, Preeti

2015-06-01

Fluoride in drinking water is known for both beneficial and detrimental effects on health. The principal sources of fluoride include water, some species of vegetation, certain edible marine animals, dust and industrial processes. The purpose of this study was to evaluate the fluoride retention of most commonly consumed estuarine fishes among fish consuming population of Andhra Pradesh. A cross-sectional study was conducted to evaluate the amount of fluoride retention due to ten most commonly consumed estuarine fishes as a contributing factor to Fluorosis by SPADNS Spectrophotometric method. The presence and severity of dental fluorosis among fish consuming population was recorded using Community Fluorosis Index. Statistical analysis was done using MedCalc v12.2.1.0 software. For Sea water fishes, the fluoride levels in bone were maximum in Indian Sardine (4.22 ppm). Amongst the river water fishes, the fluoride levels in bone were maximum in Catla (1.51 ppm). Also, the mean total fluoride concentrations of all the river fishes in skin, muscle and bone were less (0.86 ppm) as compared to the sea water fishes (2.59 ppm). It was unveiled that sea fishes accumulate relatively large amounts of Fluoride as compared to the river water fishes. The mean Community Fluorosis Index was found to be 1.06 amongst a sampled fish consuming population. Evaluation by Community Index for Dental fluorosis (CFI) suggested that fluorosis is of medium public health importance. It was analysed that bone tends to accumulate more amount of fluoride followed by muscle and skin which might be due to the increased permeability and chemical trapping of fluoride inside the tissues. The amount of fluoride present in the fishes is directly related to the severity of fluorosis amongst fish consuming population, suggesting fishes as a contributing factor to fluorosis depending upon the dietary consumption.

[Meat and fish consumption in a high cardiovascular risk Spanish Mediterranean population].

PubMed

Sotos Prieto, M; Guillen, M; Sorlí, J V; Asensio, E Ma; Gillem Sáiz, P; González, J I; Corella, D

2011-01-01

High saturated fat consumption, mostly from red meat and sausage meat has been associated with an increase in cardiovascular risk (CVR) in contrast to the effect of high fish consumption. To get to know the frequency of meat and fish consumption in an elderly high Mediterranean population, their correlations with adherence to the Mediterranean diet (MD) and their association with intermediate CVR phenotypes. A cross-sectional study was carried out on 945 people (67.4±6.2 years old) with high CVR recruited in primary care centres of Valencia, and participating in the PREDIMED study. The frequency of meat and fish consumption was determined through a validated questionnaire. We analyzed clinical, biochemical and anthropometric variables using standard methods. Mean red meat consumption was high (7.4±4.7 times/week), being higher in men than in women (P=0.031) and was associated with greater weight (P=0.001) and prevalence of obesity (P=0.025). Fish consumption was also high (4.5±2.6 time/week) and was associated with lower concentrations of fasting plasma glucose (P=0.016) as well as with lower prevalence of diabetes (P=0.017). Red meat consumption in this high CVR population is very high and far from the recommendations of MD, needing, therefore, to be reduced. Fish consumption is closer to the recommendations and should be maintained.

Genetic concepts and uncertainties in restoring fish populations and species

USGS Publications Warehouse

Reisenbichler, R.R.; Utter, F.M.; Krueger, C.C.

2003-01-01

Genetic considerations can be crucially important to the success of reintroductions of lotic species. Current paradigms for conservation and population genetics provide guidance for reducing uncertainties in genetic issues and for increasing the likelihood of achieving restoration. Effective restoration is facilitated through specific goals and objectives developed from the definition that a restored or healthy population is (i) genetically adapted to the local environment, (ii) self-sustaining at abundances consistent with the carrying capacity of the river system, (iii) genetically compatible with neighboring populations so that substantial outbreeding depression does not result from straying and interbreeding between populations, and (iv) sufficiently diverse genetically to accommodate environmental variability over many decades. Genetic principles reveal the importance of describing and adhering to the ancestral lineages for the species to be restored and enabling genetic processes to maintain diversity and fitness in the populations under restoration. Newly established populations should be protected from unnecessary human sources of mortality, gene flow from maladapted (e.g., hatchery) or exotic populations, and inadvertent selection by fisheries or other human activities. Such protection facilitates initial, rapid adaptation of the population to its environment and should enhance the chances for persistence. Various uncertainties about specific restoration actions must be addressed on a case-by-case basis. Such uncertainties include whether to allow natural colonization or to introduce fish, which populations are suitable as sources for reintroduction, appropriate levels of gene flow from other populations, appropriate levels of artificial production, appropriate minimum numbers of individuals released or maintained in the population, and the best developmental stages for releasing fish into the restored stream. Rigorous evaluation or

Dispersal capacity predicts both population genetic structure and species richness in reef fishes.

PubMed

Riginos, Cynthia; Buckley, Yvonne M; Blomberg, Simon P; Treml, Eric A

2014-07-01

Dispersal is a fundamental species characteristic that should directly affect both rates of gene flow among spatially distributed populations and opportunities for speciation. Yet no single trait associated with dispersal has been demonstrated to affect both micro- and macroevolutionary patterns of diversity across a diverse biological assemblage. Here, we examine patterns of genetic differentiation and species richness in reef fishes, an assemblage of over 7,000 species comprising approximately one-third of the extant bony fishes and over one-tenth of living vertebrates. In reef fishes, dispersal occurs primarily during a planktonic larval stage. There are two major reproductive and parental investment syndromes among reef fishes, and the differences between them have implications for dispersal: (1) benthic guarding fishes lay negatively buoyant eggs, typically guarded by the male parent, and from these eggs hatch large, strongly swimming larvae; in contrast, (2) pelagic spawning fishes release small floating eggs directly into the water column, which drift unprotected before small weakly swimming larvae hatch. Using phylogenetic comparative methods, we show that benthic guarders have significantly greater population structure than pelagic spawners and additionally that taxonomic families of benthic guarders are more species rich than families of pelagic spawners. Our findings provide a compelling case for the continuity between micro- and macroevolutionary processes of biological diversification and underscore the importance of dispersal-related traits in influencing the mode and tempo of evolution.

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

Are current efforts sufficient to ensure healthy fish populations?

Treesearch

Bob Danehy; Andy Dolloff

2013-01-01

The maintenance and conservation of fish and wildlife populations in landscapes managed for timber production is a contemporary stewardship requirement and a challenge for forest managers. Best management practices (BMPs) have been developed to meet these challenges. Most BMPs were developed starting in the 1970s so the full impact and the success of those BMPs are not...

A population-based study of fish allergy in the Philippines, Singapore and Thailand.

PubMed

Connett, Gary James; Gerez, Irvin; Cabrera-Morales, Elizabeth Ann; Yuenyongviwat, Araya; Ngamphaiboon, Jarungchit; Chatchatee, Pantipa; Sangsupawanich, Pasuree; Soh, Shu-E; Yap, Gaik-Chin; Shek, Lynette Pei-Chi; Lee, Bee-Wah

2012-01-01

Fish allergy is the third most common food allergy after milk and egg in parts of Europe, but there is little data about prevalence in South East Asia where it is an important part of regular diets. We aimed to obtain an estimate of the population prevalence of fish allergy among older children in the Philippines, Singapore and Thailand. The population prevalence of fish allergy in 14- to 16-year-old children in the 3 countries was evaluated using a structured written questionnaire which was distributed to students of randomly selected secondary schools. An extended questionnaire to determine convincing fish allergy on the basis of typical clinical manifestations within 2 h of ingestion was administered to those with positive responses. From a cohort of 25,842 students, responses were 81.1% in the Philippines (n = 11,434), 67.9% in Singapore (n = 6,498) and 80.2% (n = 2,034) in Thailand. Using criteria for convincing food allergy, fish allergy was much higher in the Philippines [2.29%, 95% confidence interval (CI) 2.02-2.56] than in Singapore (0.26%, 95% CI 0.14-0.79) and Thailand (0.29%, 95% CI 0.06-0.52). Weighted multiple logistic regression analyses showed that compared to the Philippines, prevalence rates were lower in Singapore [odds ratio (OR) 0.40, 95% CI 0.27-0.60, p < 0.0001] and Thailand (OR 0.13, 95% CI 0.05-0.33, p < 0.0001). Females were more likely to have fish allergy compared to males for all children combined (OR 1.32, 95% CI 1.11-1.58, p = 0.002). Most allergies appeared mild, as only 28% of cases sought medical consultation at the time of the reaction and 31.2% of cases reported continued exposure despite allergic symptoms. Fish allergy in late childhood is more common in the Philippines compared to Singapore and Thailand. Differences in food processing, dietary habits and other cultural practices might be important risk factors for the development of fish allergy in these populations. Copyright © 2012 S. Karger AG, Basel.

Compensatory mechanisms in fish populations: Literature reviews: Volume 1, Critical evaluation of case histories of fish populations experiencing chronic exploitation or impact: Final report

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

Saila, S.B.; Chen, X.; Erzini, K.

1987-05-01

This study includes case histories of certain fish species which are experiencing chronic perturbations and related literature pertaining to compensation processes. ''Compensation'' has been defined as the ability of fish to offset the population reduction caused by natural or man-induced stresses. Certain compensation methods are widely accepted, and include cannibalism, competition, disease, growth and predation, among others. These compensation methods are examined in relation to each fish species included in the study. Stock-recruit relationships and empirical observations of changes in growth and mortality have been the focus of much of the background on compensation. One of the conclusions drawn frommore » this study is that a significant amount of recruitment variability exists and can be attributed to environmental (rather than compensatory) factors. The stock-recruitment problem appears to be the most significant scientific problem related to compensation in the types of fish included in this study. Results of the most recent studies of the American shad support this theory. Life histories, breeding biology and other pertinent data relating to each species included in the study will be found in the appendices.« less

Hydropower impacts on reservoir fish populations are modified by environmental variation.

PubMed

Eloranta, Antti P; Finstad, Anders G; Helland, Ingeborg P; Ugedal, Ola; Power, Michael

2018-03-15

Global transition towards renewable energy production has increased the demand for new and more flexible hydropower operations. Before management and stakeholders can make informed choices on potential mitigations, it is essential to understand how the hydropower reservoir ecosystems respond to water level regulation (WLR) impacts that are likely modified by the reservoirs' abiotic and biotic characteristics. Yet, most reservoir studies have been case-specific, which hampers large-scale planning, evaluation and mitigation actions across various reservoir ecosystems. Here, we investigated how the effect of the magnitude, frequency and duration of WLR on fish populations varies along environmental gradients. We used biomass, density, size, condition and maturation of brown trout (Salmo trutta L.) in Norwegian hydropower reservoirs as a measure of ecosystem response, and tested for interacting effects of WLR and lake morphometry, climatic conditions and fish community structure. Our results showed that environmental drivers modified the responses of brown trout populations to different WLR patterns. Specifically, brown trout biomass and density increased with WLR magnitude particularly in large and complex-shaped reservoirs, but the positive relationships were only evident in reservoirs with no other fish species. Moreover, increasing WLR frequency was associated with increased brown trout density but decreased condition of individuals within the populations. WLR duration had no significant impacts on brown trout, and the mean weight and maturation length of brown trout showed no significant response to any WLR metrics. Our study demonstrates that local environmental characteristics and the biotic community strongly modify the hydropower-induced WLR impacts on reservoir fishes and ecosystems, and that there are no one-size-fits-all solutions to mitigate environmental impacts. This knowledge is vital for sustainable planning, management and mitigation of hydropower

A systematic review of epidemiological literature on the eye health of marginalized fishing populations.

PubMed

Ahmad, Khabir; B Zwi, Anthony; J M Tarantola, Daniel; Chand, Bal

2016-10-01

A systematic review was conducted in December 2013 to examine the extent to which health research has been focused on the eye health issues of fishing communities. We searched multiple databases to identify relevant citations, using a combination of Medical Subject Headings (MeSH) and text words representing eye health, fishing populations and measures of disease frequency. The search yielded only 4 studies, described in 5 articles. Three studies (one each in Turkey, Egypt and Spain) provided data on self-reported eye problems in fishermen or fishery workers, with prevalence ranging from 38% to 81%. There was only one study in the literature that objectively assessed the burden and causes of vision impairment and blindness in fishing communities. None of the studies examined availability, accessibility, acceptability and quality of eye care services. We conclude that marginalized fishing communities are almost non-existent in eye health literature. Eye health needs of these and other marginalized populations must be identified and addressed in post-2015 health and development agenda.

Population expansions dominate demographic histories of endemic and widespread Pacific reef fishes.

PubMed

Delrieu-Trottin, Erwan; Mona, Stefano; Maynard, Jeffrey; Neglia, Valentina; Veuille, Michel; Planes, Serge

2017-01-16

Despite the unique nature of endemic species, their origin and population history remain poorly studied. We investigated the population history of 28 coral reef fish species, close related, from the Gambier and Marquesas Islands, from five families, with range size varying from widespread to small-range endemic. We analyzed both mitochondrial and nuclear sequence data using neutrality test and Bayesian analysis (EBSP and ABC). We found evidence for demographic expansions for most species (24 of 28), irrespective of range size, reproduction strategy or archipelago. The timing of the expansions varied greatly among species, from 8,000 to 2,000,000 years ago. The typical hypothesis for reef fish that links population expansions to the Last Glacial Maximum fit for 14 of the 24 demographic expansions. We propose two evolutionary processes that could lead to expansions older than the LGM: (a) we are retrieving the signature of an old colonization process for widespread, large-range endemic and paleoendemic species or (b) speciation; the expansion reflects the birth of the species for neoendemic species. We show for the first time that the demographic histories of endemic and widespread reef fish are not distinctly different and suggest that a number of processes drive endemism.

Status and trends of prey fish populations in Lake Michigan, 2013

USGS Publications Warehouse

Madenjian, Charles P.; Bunnell, David B.; Desorcie, Timothy J.; Kostich, Melissa Jean; Armenio, Patricia M.; Adams, Jean V.

2015-01-01

The U.S. Geological Survey Great Lakes Science Center has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size and age structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2013. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2013 was estimated at 29 kilotonnes (kt, 1 kt = 1000 metric tonnes), which was more than three times the 2012 estimate. However, the unusually high standard error associated with the 2013 estimate indicated no significant increase in lake-wide biomass between 2012 and 2013. Moreover, the age distribution of alewives remained truncated with no alewife exceeding an age of 5. The population of age-1 and older alewives was dominated (i.e., 88%) by the 2010 and 2012 year-classes. Record low biomass was observed for deepwater sculpin (1.3 kt) and ninespine stickleback (0.004 kt) in 2013, while bloater (1.6 kt) and rainbow smelt (0.2 kt) biomasses remained at low levels. Slimy sculpin lake-wide biomass was 0.32 kt in 2013, marking the fourth consecutive year of a decline. The 2013 biomass of round goby was estimated at 10.9 kt, which represented the peak estimate to date. Burbot lake-wide biomass (0.4 kt in 2013) has remained below 3 kt since 2001. Numeric density of age-0 yellow perch (i.e., < 100 mm) was only 1 fish per ha, which is indicative of a relatively poor year-class. Lake-wide biomass estimate of dreissenid mussels in 2013 was 23.2 kt

Connectivity, passability and heterogeneity interact to determine fish population persistence in river networks

PubMed Central

Samia, Yasmine; Lutscher, Frithjof; Hastings, Alan

2015-01-01

The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a ‘retention effect’. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics. PMID:26311313

Connectivity, passability and heterogeneity interact to determine fish population persistence in river networks.

PubMed

Samia, Yasmine; Lutscher, Frithjof; Hastings, Alan

2015-09-06

The movement of fish in watersheds is frequently inhibited by human-made migration barriers such as dams or culverts. The resulting lack of connectivity of spatial subpopulations is often cited as a cause for observed population decline. We formulate a matrix model for a spatially distributed fish population in a watershed, and we investigate how location and other characteristics of a single movement barrier impact the asymptotic growth rate of the population. We find that while population growth rate often decreases with the introduction of a movement obstacle, it may also increase due to a 'retention effect'. Furthermore, obstacle mortality greatly affects population growth rate. In practice, different connectivity indices are used to predict population effects of migration barriers, but the relation of these indices to population growth rates in demographic models is often unclear. When comparing our results with the dentritic connectivity index, we see that the index captures neither the retention effect nor the influences of obstacle mortality. We argue that structural indices cannot entirely replace more detailed demographic models to understand questions of persistence and extinction. We advocate the development of novel functional indices and characteristics. © 2015 The Author(s).

Density regulation in Northeast Atlantic fish populations: Density dependence is stronger in recruitment than in somatic growth.

PubMed

Zimmermann, Fabian; Ricard, Daniel; Heino, Mikko

2018-05-01

Population regulation is a central concept in ecology, yet in many cases its presence and the underlying mechanisms are difficult to demonstrate. The current paradigm maintains that marine fish populations are predominantly regulated by density-dependent recruitment. While it is known that density-dependent somatic growth can be present too, its general importance remains unknown and most practical applications neglect it. This study aimed to close this gap by for the first time quantifying and comparing density dependence in growth and recruitment over a large set of fish populations. We fitted density-dependent models to time-series data on population size, recruitment and age-specific weight from commercially exploited fish populations in the Northeast Atlantic Ocean and the Baltic Sea. Data were standardized to enable a direct comparison within and among populations, and estimated parameters were used to quantify the impact of density regulation on population biomass. Statistically significant density dependence in recruitment was detected in a large proportion of populations (70%), whereas for density dependence in somatic growth the prevalence of density dependence depended heavily on the method (26% and 69%). Despite age-dependent variability, the density dependence in recruitment was consistently stronger among age groups and between alternative approaches that use weight-at-age or weight increments to assess growth. Estimates of density-dependent reduction in biomass underlined these results: 97% of populations with statistically significant parameters for growth and recruitment showed a larger impact of density-dependent recruitment on population biomass. The results reaffirm the importance of density-dependent recruitment in marine fishes, yet they also show that density dependence in somatic growth is not uncommon. Furthermore, the results are important from an applied perspective because density dependence in somatic growth affects productivity and

Short winters threaten temperate fish populations

PubMed Central

Farmer, Troy M.; Marschall, Elizabeth A.; Dabrowski, Konrad; Ludsin, Stuart A.

2015-01-01

Although climate warming is expected to benefit temperate ectotherms by lengthening the summer growing season, declines in reproductive success following short, warm winters may counter such positive effects. Here we present long-term (1973–2010) field patterns for Lake Erie yellow perch, Perca flavescens, which show that failed annual recruitment events followed short, warm winters. Subsequent laboratory experimentation and field investigations revealed how reduced reproductive success following short, warm winters underlie these observed field patterns. Following short winters, females spawn at warmer temperatures and produce smaller eggs that both hatch at lower rates and produce smaller larvae than females exposed to long winters. Our research suggests that continued climate warming can lead to unanticipated, negative effects on temperate fish populations. PMID:26173734

Does mobility explain variation in colonisation and population recovery among stream fishes?

USGS Publications Warehouse

Angermeier, Paul L.; Albanese, Brett; Peterson, James T.

2009-01-01

1. Colonisation and population recovery are crucial to species persistence in environmentally variable ecosystems, but are poorly understood processes. After documenting movement rates for several species of stream fish, we predicted that this variable would influence colonisation rates more strongly than local abundance, per cent occupancy, body size and taxonomic family. We also predicted that populations of species with higher movement rates would recover more rapidly than species with lower movement rates and that assemblage structure would change accordingly. 2. To test these predictions, we removed fishes from a headwater and a mainstem creek in southwest Virginia and monitored colonisation over a 2-year period. Using an information–theoretic approach, we evaluated the relative plausibility of 15 alternative models containing different combinations of our predictor variables. Our best-supported model contained movement rate and abundance and was 41 times more likely to account for observed patterns in colonisation rates than the next-best model. Movement rate and abundance were both positively related to colonisation rates and explained 88% of the variation in colonisation rates among species. 3. Population recovery, measured as the per cent of initial abundance restored, was also positively associated with movement rate. One species recovered within 3 months, most recovered within 2 years, but two species still had not recovered after 2 years. Despite high variation in recovery, the removal had only a slight impact on assemblage structure because species that were abundant in pre-removal samples were also abundant in post-removal samples. 4. The significance of interspecific variation in colonisation and recovery rates has been underappreciated because of the widely documented recovery of stream fish assemblages following fish kills and small-scale experimental defaunations. Our results indicate that recovery of the overall assemblage does not imply

Ocean acidification alters fish populations indirectly through habitat modification

NASA Astrophysics Data System (ADS)

Nagelkerken, Ivan; Russell, Bayden D.; Gillanders, Bronwyn M.; Connell, Sean D.

2016-01-01

Ocean ecosystems are predicted to lose biodiversity and productivity from increasing ocean acidification. Although laboratory experiments reveal negative effects of acidification on the behaviour and performance of species, more comprehensive predictions have been hampered by a lack of in situ studies that incorporate the complexity of interactions between species and their environment. We studied CO2 vents from both Northern and Southern hemispheres, using such natural laboratories to investigate the effect of ocean acidification on plant-animal associations embedded within all their natural complexity. Although we substantiate simple direct effects of reduced predator-avoidance behaviour by fishes, as observed in laboratory experiments, we here show that this negative effect is naturally dampened when fish reside in shelter-rich habitats. Importantly, elevated CO2 drove strong increases in the abundance of some fish species through major habitat shifts, associated increases in resources such as habitat and prey availability, and reduced predator abundances. The indirect effects of acidification via resource and predator alterations may have far-reaching consequences for population abundances, and its study provides a framework for a more comprehensive understanding of increasing CO2 emissions as a driver of ecological change.

Distance, dams and drift: What structures populations of an endangered, benthic stream fish?

USGS Publications Warehouse

Roberts, James H.; Angermeier, Paul; Hallerman, Eric M.

2013-01-01

Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied. We investigated the range-wide population genetic structure of Roanoke logperch (Percina rex), an endangered, benthic stream fish of the eastern United States. Fish were sampled from 35 sites and analysed at 11 microsatellite DNA loci. Clustering models were used to sort individuals into genetically cohesive groups and thereby estimate the spatial scaling of population structure. We then used Bayesian generalized linear mixed models (BGLMMs) to test alternative hypotheses about the environmental factors most responsible for generating structure, as measured by the differentiation statistic FST. Clustering models delineated seven discrete populations, whose boundaries coincided with agents of fragmentation, including hydroelectric dams and tailwaters. In the absence of hydrological barriers, gene flow was extensive throughout catchments, whereas there was no evidence for contemporary dispersal between catchments across barriers. In the best-supported BGLMM, FST was positively related to the spatial distance and degree of hydrological alteration between sites and negatively related to genetic diversity within sites. Whereas the effect of tailwaters was equivocal, dams strongly influenced differentiation: the effect of a dam on FST was comparable to that of a between-site distance of over 1200 km of unimpounded river. Overall, the effect of distance-mediated dispersal was negligible compared to the combined effects of fragmentation and genetic drift. The contemporary population structure of P. rex comprises a few geographically extensive ‘islands’ that are fragmented by hydroelectric projects. This information clarifies the importance of a catchment-scale perspective on conserving the species and

ECOLOGICAL ENDPOINT MODELING FOR TMDLS: EFFECTS OF SEDIMENT ON FISH POPULATIONS

EPA Science Inventory

Sediment is one of the primary stressors of concern for Total Maximum Daily Loads (TMDLs) for streams, and often it is a concern because of its impact on ecological endpoints. A modeling approach relating sediment to stream fish population dynamics is presented. Equations are d...

Does a predatory insect contribute to the divergence between cave- and surface-adapted fish populations?

PubMed Central

Tobler, Michael

2009-01-01

Immigrant inviability, where individuals from foreign, ecologically divergent habitats are less likely to survive, can restrict gene flow among diverging populations and result in speciation. I investigated whether a predatory aquatic insect (Belostoma sp.) selects against migrants between cave and surface populations of a fish (Poecilia mexicana). Cavefish were more susceptible to attacks in the light, whereas surface fish were more susceptible in darkness. Environmentally dependent susceptibility to attacks may thus contribute to genetic and phenotypic differentiation between the populations. This study highlights how predation—in this case in conjunction with differences in other environmental factors—can be an important driver in speciation. PMID:19443506

EFFECTS OF BENZO[A]PYRENE EXPOSURE ON A FISH POPULATION RESISTANT TO THE TOXIC EFFECTS OF DIOXIN-LIKE COMPOUNDS

EPA Science Inventory

Effects of a model polycyclic aromatic hydrocarbon (PAH) were compared in populations of the estuarine fish Fundulus heteroclitus indigenous to a reference site and one highly contaminated with polychlorinated biphenyls (PCBs) and other compounds. The fish population resident to ...

The power to detect trends in Missouri River fish populations within the Pallid Sturgeon Population Assessment Program

USGS Publications Warehouse

Bryan, Janice L.; Wildhaber, Mark L.; Gladish, Dan; Holan, Scott; Ellerseick, Mark

2010-01-01

As with all large rivers in the United States, the Missouri River has been altered, with approximately 32.5 percent of the main stem length impounded and 32.5 percent channelized. These physical alterations to the environment have had effects on the fisheries, but studies examining the effects of alterations have been localized and for short periods of time. In response to the U.S. Fish and Wildlife Service biological opinion, the U.S. Army Corps of Engineers initiated monitoring of the fish community of the Missouri River in 2003. The goal of the Pallid Sturgeon Population Assessment Program is to provide information to detect changes in populations and habitat preferences with time for pallid sturgeon (Scaphirhynchus albus) and native target species in the Missouri River Basin. To determine statistical power of the Pallid Sturgeon Population Assessment Program, a power analysis was conducted using a normal linear mixed model with variance component estimates based on the first 3 years of data (2003 to 2005). In cases where 3 years of data were unavailable, estimates were obtained using those data. It was determined that at least 20 years of data, sampling 12 bends with 8 subsamples per bend, would be required to detect a 5 percent annual decline in most of the target fish populations. Power varied between Zones. Zone 1 (upstream from Lake Sakakawea) did not have any species/gear type combinations with adequate power, whereas Zone 3 (downstream from Gavins Point Dam) had 19 species/gear type combinations with adequate power. With a slight increase in the sampling effort to 12 subsamples per bend, the Pallid Sturgeon Population Assessment Program has adequate power to detect declines in shovelnose sturgeon (S. platorynchus) throughout the entire Missouri River because of large catch rates. The lowest level of non-occurrence (in other words, zero catches) at the bend level for pallid sturgeon was 0.58 using otter trawls in Zone 1. Consequently, the power of the

The impacts of mobile fishing gear on seafloor habitats in the Gulf of Maine (Northwest Atlantic): implications for conservation of fish populations

USGS Publications Warehouse

Auster, Peter J.; Malatesta, Richard J.; Langton, Richard W.; Watting, Les; Valentine, Page C.; Donaldson, Carol Lee S.; Langton, Elizabeth W.; Shepard, Andrew N.; Babb, War G.

1997-01-01

Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects, have not been quantified extensively in the northwest Atlantic. Understanding the extent of these impacts, and their effects on populations of living marine resources, is needed to properly manage current and future levels of fishing effort and fishing power. For example, the entire U.S. side of the Gulf of Maine was impacted annually by mobile fishing gear between 1984 and 1990, based on calculations of area swept by trawl and dredge gear. Georges Bank was imparted three to nearly four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical structure (=complexity) of benthic habitats. Complexity was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and‐ sedimentary (e.g., sand waves, depressions) structures. Also, removal of organisms that create.structures (e.g., crabs, scallops) indirectly reduced complexity. Reductions in habitat complexity may lead to increased predation on juveniles of harvested species and ultimately recruitment to the harvestable stock. Because of a lack of reference sites, where use of mobile fishing is prohibited, no empirical studies have yet been conducted on a scale that could demonstrate population level effects of habitat‐management options. If marine fisheries management is to evolve toward an ecosystem or habitat management approach, experiments are required on the effects of habitat change, both anthropogenic and natural.

The impacts of mobile fishing gear on seafloor habitats in the gulf of maine (Northwest Atlantic): Implications for conservation of fish populations

USGS Publications Warehouse

Auster, P.J.; Malatesta, R.J.; Langton, R.W.; Watling, Les; Valentine, P.C.; Donaldson, C.L.S.; Langton, E.W.; Shepard, A.N.; Babb, Ivar G.

1996-01-01

Fishing gear alters seafloor habitats, but the extent of these alterations, and their effects, have not been quantified extensively in the northwest Atlantic. Understanding the extent of these impacts, and their effects on populations of living marine resources, is needed to properly manage current and future levels of fishing effort and fishing power. For example, the entire U.S. side of the Gulf of Maine was impacted annually by mobile fishing gear between 1984 and 1990, based on calculations of area swept by trawl and dredge gear. Georges Bank was impacted three to nearly four times annually during the same period. Studies at three sites in the Gulf of Maine (off Swans Island, Jeffreys Bank, and Stellwagen Bank) showed that mobile fishing gear altered the physical structure (=complexity) of benthic habitats. Complexity was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and sedimentary (e.g., sand waves, depressions) structures. Also, removal of organisms that create structures (e.g., crabs, scallops) indirectly reduced complexity. Reductions in habitat complexity may lead to increased predation on juveniles of harvested species and ultimately recruitment to the harvestable stock. Because of a lack of reference sites, where use of mobile fishing is prohibited, no empirical studies have yet been conducted on a scale that could demonstrate population level effects of habitat-management options. If marine fisheries management is to evolve toward an ecosystem or habitat management approach, experiments are required on the effects of habitat change, both anthropogenic and natural.

Relative distribution and abundance of fishes and crayfish in 2010 and 2014 prior to saltcedar (Tamarix ssp.) removal in the Amargosa River Canyon, southeastern California

USGS Publications Warehouse

Hereford, Mark E.

2016-07-22

The Amargosa River Canyon, located in the Mojave Desert of southeastern California, contains the longest perennial reach of the Amargosa River. Because of its diverse flora and fauna, it has been designated as an Area of Critical Environmental Concern and a Wild and Scenic River by the Bureau of Land Management. A survey of fishes conducted in summer 2010 indicated that endemic Amargosa River pupfish (Cyprinodon nevadensis amargosae) and speckled dace (Rhinichthys osculus spp.) were abundant and occurred throughout the Amargosa River Canyon. The 2010 survey reported non-native red swamp crayfish (Procambarus clarkii) and western mosquitofish (Gambusia affinis) captures were significantly higher, whereas pupfish captures were lower, in areas dominated by non-native saltcedar (Tamarix ssp.). Based on the 2010 survey, it was hypothesized that the invasion of saltcedar could result in a decrease in native species. In an effort to maintain and enhance native fish populations, the Bureau of Land Management removed saltcedar from a 1,550 meter reach of stream on the Amargosa River in autumn 2014 and autumn 2015. Prior to the removal of saltcedar, a survey of fishes and crayfish using baited minnow traps was conducted in the treatment reach to serve as a baseline for future comparisons with post-saltcedar removal surveys. During the 2014 survey, 1,073 pupfish and 960 speckled dace were captured within the treatment reach. Catch per unit effort of pupfish and speckled dace in the treatment reach was less in 2014 than in 2010, although differences could be owing to seasonal variation in capture probability. Non-native mosquitofish catch per unit effort decreased from 2010 to 2014; however, the catch per unit effort of crayfish increased from 2010 to 2014. Future monitoring efforts of this reach should be conducted at the same time period to account for potential seasonal fluctuations of abundance and distribution of fishes and crayfish. A more robust study design that

Tuning stochastic matrix models with hydrologic data to predict the population dynamics of a riverine fish

USGS Publications Warehouse

Sakaris, P.C.; Irwin, E.R.

2010-01-01

We developed stochastic matrix models to evaluate the effects of hydrologic alteration and variable mortality on the population dynamics of a lotie fish in a regulated river system. Models were applied to a representative lotic fish species, the flathead catfish (Pylodictis olivaris), for which two populations were examined: a native population from a regulated reach of the Coosa River (Alabama, USA) and an introduced population from an unregulated section of the Ocmulgee River (Georgia, USA). Size-classified matrix models were constructed for both populations, and residuals from catch-curve regressions were used as indices of year class strength (i.e., recruitment). A multiple regression model indicated that recruitment of flathead catfish in the Coosa River was positively related to the frequency of spring pulses between 283 and 566 m3/s. For the Ocmulgee River population, multiple regression models indicated that year class strength was negatively related to mean March discharge and positively related to June low flow. When the Coosa population was modeled to experience five consecutive years of favorable hydrologic conditions during a 50-year projection period, it exhibited a substantial spike in size and increased at an overall 0.2% annual rate. When modeled to experience five years of unfavorable hydrologic conditions, the Coosa population initially exhibited a decrease in size but later stabilized and increased at a 0.4% annual rate following the decline. When the Ocmulgee River population was modeled to experience five years of favorable conditions, it exhibited a substantial spike in size and increased at an overall 0.4% annual rate. After the Ocmulgee population experienced five years of unfavorable conditions, a sharp decline in population size was predicted. However, the population quickly recovered, with population size increasing at a 0.3% annual rate following the decline. In general, stochastic population growth in the Ocmulgee River was more

Tuning stochastic matrix models with hydrologic data to predict the population dynamics of a riverine fish.

PubMed

Sakaris, Peter C; Irwin, Elise R

2010-03-01

We developed stochastic matrix models to evaluate the effects of hydrologic alteration and variable mortality on the population dynamics of a lotic fish in a regulated river system. Models were applied to a representative lotic fish species, the flathead catfish (Pylodictis olivaris), for which two populations were examined: a native population from a regulated reach of the Coosa River (Alabama, USA) and an introduced population from an unregulated section of the Ocmulgee River (Georgia, USA). Size-classified matrix models were constructed for both populations, and residuals from catch-curve regressions were used as indices of year class strength (i.e., recruitment). A multiple regression model indicated that recruitment of flathead catfish in the Coosa River was positively related to the frequency of spring pulses between 283 and 566 m3/s. For the Ocmulgee River population, multiple regression models indicated that year class strength was negatively related to mean March discharge and positively related to June low flow. When the Coosa population was modeled to experience five consecutive years of favorable hydrologic conditions during a 50-year projection period, it exhibited a substantial spike in size and increased at an overall 0.2% annual rate. When modeled to experience five years of unfavorable hydrologic conditions, the Coosa population initially exhibited a decrease in size but later stabilized and increased at a 0.4% annual rate following the decline. When the Ocmulgee River population was modeled to experience five years of favorable conditions, it exhibited a substantial spike in size and increased at an overall 0.4% annual rate. After the Ocmulgee population experienced five years of unfavorable conditions, a sharp decline in population size was predicted. However, the population quickly recovered, with population size increasing at a 0.3% annual rate following the decline. In general, stochastic population growth in the Ocmulgee River was more

High population density enhances recruitment and survival of a harvested coral reef fish.

PubMed

Wormald, Clare L; Steele, Mark A; Forrester, Graham E

2013-03-01

A negative relationship between population growth and population density (direct density dependence) is necessary for population regulation and is assumed in most models of harvested populations. Experimental tests for density dependence are lacking for large-bodied, harvested fish because of the difficulty of manipulating population density over large areas. We studied a harvested coral reef fish, Lutjanus apodus (schoolmaster snapper), using eight large, isolated natural reefs (0.4-1.6 ha) in the Bahamas as replicates. An initial observational test for density dependence was followed by a manipulation of population density. The manipulation weakened an association between density and shelter-providing habitat features and revealed a positive effect of population density on recruitment and survival (inverse density dependence), but no effect of density on somatic growth. The snappers on an individual reef were organized into a few shoals, and we hypothesize that large shoals on high-density reefs were less vulnerable to large piscivores (groupers and barracudas) than the small shoals on low-density reefs. Reductions in predation risk for individuals in large social groups are well documented, but because snapper shoals occupied reefs the size of small marine reserves, these ecological interactions may influence the outcome of management actions.

Status and trends of prey fish populations in Lake Michigan, 2008

USGS Publications Warehouse

Bunnell, David B.; Madenjian, Charles P.; Holuszko, Jeffrey D.; Desorcie, Timothy J.; Adams, Jean V.

2009-01-01

The Great Lakes Science Center (GLSC) has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2008. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2008 was estimated at 8.27 kilotonnes (kt) (1 kt = 1000 metric tons), which was the smallest biomass estimate in the entire time series and 29% lower than the 2007 estimate. Lake-wide biomass of bloater in 2008 was estimated at 3.33 kt, which was the lowest estimate since 1977 and 38% lower than the 2007 estimate. Rainbow smelt lake-wide biomass equaled 0.89 kt, which was only 0.01 kt higher than 2007, which is the lowest estimate in the time series. Deepwater sculpin lake-wide biomass equaled 5.23 kt, which is the fourth straight year of declining biomass. The 2008 estimate is the second smallest in the time series, and 39% lower than the 2007 estimate. Slimy sculpin lake-wide biomass remained relatively high in 2008 (2.75 kt), increasing 25% over 2007. Ninespine stickleback lake-wide biomass equaled only 0.50 kt in 2008, which was 79% lower than the 2007 estimate. The final prey fish, exotic round goby, increased two orders of magnitude between 2007 and 2008, from 0.02 to 4.65 kt. Round gobies now represent 18% of the prey fish biomass. Burbot lake-wide biomass (0.91 kt in 2008) has remained fairly constant since 2002. Numeric density of age-0 yellow perch (i

Status and trends of prey fish populations in Lake Michigan, 2012

USGS Publications Warehouse

Bunnell, David B.; Madenjian, Charles P.; Desorcie, Timothy J.; Kostich, Melissa Jean; Smith, Kelley R.; Adams, Jean V.

2012-01-01

The U.S. Geological Survey Great Lakes Science Center has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size and age structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2012. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2012 was estimated at 9 kilotonnes (kt, 1 kt = 1000 metric tonnes), which continues the trend of unusually low alewife biomass since 2004 but represented a 20% increase from the 2011 estimate. The age distribution of alewives larger than 100 mm was dominated (i.e., 84%) by age-2. Record low biomass was observed for several species, including bloater (0.4 kt), rainbow smelt (0.1 kt), deepwater sculpin (1.5 kt), and ninespine stickleback (0.01 kt). Slimy sculpin lake-wide biomass was 0.73 kt in 2012, which was the third consecutive year revealing a decline. Estimated biomass of round goby increased by 79% to 3 kt. Burbot lake-wide biomass (0.5 kt in 2012) has remained below 3 kt since 2001. Numeric density of age-0 yellow perch (i.e., < 100 mm) was only 2 fish per ha, which is indicative of a relatively poor year-class. Lake-wide biomass estimates of dreissenid mussels have continued to increase from 2010, from 12 to 95 kt in 2012. Overall, the total lake-wide prey fish biomass estimate (sum of alewife, bloater, rainbow smelt, deepwater sculpin, slimy sculpin, round goby, and ninespine stickleback) in 2012 was 15 kt, which represented the

Design complexity in termite-fishing tools of chimpanzees (Pan troglodytes)

PubMed Central

Sanz, Crickette; Call, Josep; Morgan, David

2009-01-01

Adopting the approach taken with New Caledonian crows (Corvus moneduloides), we present evidence of design complexity in one of the termite-fishing tools of chimpanzees (Pan troglodytes) in the Goualougo Triangle, Republic of Congo. Prior to termite fishing, chimpanzees applied a set of deliberate, distinguishable actions to modify herb stems to fashion a brush-tipped probe, which is different from the form of fishing tools used by chimpanzees in East and West Africa. This means that ‘brush-tipped fishing probes’, unlike ‘brush sticks’, are not a by-product of use but a deliberate design feature absent in other chimpanzee populations. The specialized modifications to prepare the tool for termite fishing, measures taken to repair non-functional brushes and appropriate orientation of the modified end suggest that these wild chimpanzees are attentive to tool modifications. We also conducted experimental trials that showed that a brush-tipped probe is more effective in gathering insects than an unmodified fishing probe. Based on these findings, we suggest that chimpanzees in the Congo Basin have developed an improved fishing probe design. PMID:19324641

Genetic structure and diversity in natural and stocked populations of the mandarin fish (Siniperca chuatsi) in China.

PubMed

Yang, M; Tian, C; Liang, X-F; Zheng, H; Zhao, C; Zhu, K

2015-05-18

The Chinese perch, or mandarin fish (Siniperca chuatsi), is a freshwater fish that is endemic to East Asia. In this study, we investigated the genetic diversity and structure of nine natural mandarin fish populations (from the Yangtze River and Amur River basins) and six hatchery stocks (from central and south China) using microsatellite markers. The results show that the genetic diversity of the Yangtze River populations was high and stable, and genetic differences between them were not significant. In contrast, a low level of genetic diversity and strong genetic structure were detected in the Amur River population. These results suggest that the Yangtze River region and the Amur River region should be treated as two separate units in conservation programs. The hatchery stocks exhibited low genetic diversity and significant genetic differentiation compared to natural populations; this may result in a significant impact on the species if escape events occur. Therefore, a scientific aquaculture management strategy is necessary for the long-term development of hatcheries.

Prevalence and Population Structure of Vibrio vulnificus on Fishes from the Northern Gulf of Mexico

PubMed Central

Tao, Zhen; Larsen, Andrea M.; Bullard, Stephen A.; Wright, Anita C.

2012-01-01

The prevalence of Vibrio vulnificus on the external surfaces of fish from the northern Gulf of Mexico was determined in this study. A collection of 242 fish comprising 28 species was analyzed during the course of 12 sampling trips over a 16-month period. The prevalence of V. vulnificus was 37% but increased up to 69% in summer. A positive correlation was found between the percentages of V. vulnificus-positive fish and water temperatures, while salinity and V. vulnificus-positive fish prevalence were inversely correlated. A general lineal model (percent V. vulnificus-positive fish = 0.5930 − 0.02818 × salinity + 0.01406 × water temperature) was applied to best fit the data. Analysis of the population structure was carried out using 244 isolates recovered from fish. Ascription to 16S rRNA gene types indicated that 157 isolates were type A (62%), 72 (29%) were type B, and 22 (9%) were type AB. The percentage of type B isolates, considered to have greater virulence potential, was higher than that previously reported in oyster samples from the northern Gulf of Mexico. Amplified fragment length polymorphism (AFLP) was used to resolve the genetic diversity within the species. One hundred twenty-one unique AFLP profiles were found among all analyzed isolates, resulting in a calculated Simpson's index of diversity of 0.991. AFLP profiles were not grouped on the basis of collection date, fish species, temperature, or salinity, but isolates were clustered into two main groups that correlated precisely with 16S rRNA gene type. The population of V. vulnificus associated with fishes from the northern Gulf of Mexico is heterogeneous and includes strains of great virulence potential. PMID:22923394

Toxic materials, fishing, and environmental variation: simulated effects on striped bass population trends

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

Goodyear, C.P.

1985-01-01

Decreased survival of larval striped bass Morone saxatilis resulting from toxic chemicals in the environment and decreased survival of adults caused by fishing both are suspected as agents contributing to the decline in the Chesapeake Bay stock since the mid-1970s. The relative power of each type of mortality to cause population declines was evaluated with simulation techniques. Equivalent levels of added mortality induced qualitatively identical and quantitatively similar trends in population simulations for all conditions examined except if strong density-dependent mortality preceded the contaminant toxicity. In this case the contaminant effect caused a greater reduction in yield, but the populationmore » did not tend toward extinction. The results indicate that the observed downward trend in the Chesapeake Bay population can be halted or reversed by a reduction in fishing mortality, even if contaminant toxicity is the proximate cause for the decline. 28 references, 1 figure, 1 table.« less

High-throughput telomere length quantification by FISH and its application to human population studies.

PubMed

Canela, Andrés; Vera, Elsa; Klatt, Peter; Blasco, María A

2007-03-27

A major limitation of studies of the relevance of telomere length to cancer and age-related diseases in human populations and to the development of telomere-based therapies has been the lack of suitable high-throughput (HT) assays to measure telomere length. We have developed an automated HT quantitative telomere FISH platform, HT quantitative FISH (Q-FISH), which allows the quantification of telomere length as well as percentage of short telomeres in large human sample sets. We show here that this technique provides the accuracy and sensitivity to uncover associations between telomere length and human disease.

COMPLIANCE STUDIES: WHAT ABOUT THE FISH?

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

Woodley, Christa M.; Fischer, Eric S.; Wagner, Katie A.

2013-08-21

ABSTRACT It is understood that operational and structural conditions at hydroelectric facilities along with environmental conditions of the migration corridors affect the passage conditions for fish. Hydropower fish survival assessments at the individual- and population-level have progressed over the past decade with development of turbine simulation software and improvements in telemetry systems, in particular, micro-transmitters, cabled and autonomous receivers, and advanced statistical designs that provide precise estimates of passage routes and dam-passage survival. However, these approaches often ignore fish condition as a variable in passage and survival analyses. To account for fish condition effects on survival results, compliance statistical modelsmore » often require increased numbers of tagged fish. For example, prior to and during migration, fish encounter numerous stressors (e.g., disease, predation, contact with structures, decompression events), all of which can cause physical and physiological stress, altering the probability of survival after passage through a dam or a series of dams. In addition, the effects of surgical transmitter implantation process or the transmitter itself may cause physiological stress, alter behavior, and/or decrease survival. Careful physiological evaluations can augment survival model assumptions, resultant data, and predictive scenarios. To exemplify this, surgeons concurrently noted fish condition and surgical implantation during a multi-dam compliance study in 2011. The analyses indicted that surgeon observations on fish condition and surgical outcomes were related to 24 h holding mortalities and fish that never detected after release. Short reach and long reach survival were related to surgical outcomes and fish condition, respectively.« less

Visual Basic, Excel-based fish population modeling tool - The pallid sturgeon example

USGS Publications Warehouse

Moran, Edward H.; Wildhaber, Mark L.; Green, Nicholas S.; Albers, Janice L.

2016-02-10

The model presented in this report is a spreadsheet-based model using Visual Basic for Applications within Microsoft Excel (http://dx.doi.org/10.5066/F7057D0Z) prepared in cooperation with the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service. It uses the same model structure and, initially, parameters as used by Wildhaber and others (2015) for pallid sturgeon. The difference between the model structure used for this report and that used by Wildhaber and others (2015) is that variance is not partitioned. For the model of this report, all variance is applied at the iteration and time-step levels of the model. Wildhaber and others (2015) partition variance into parameter variance (uncertainty about the value of a parameter itself) applied at the iteration level and temporal variance (uncertainty caused by random environmental fluctuations with time) applied at the time-step level. They included implicit individual variance (uncertainty caused by differences between individuals) within the time-step level.The interface developed for the model of this report is designed to allow the user the flexibility to change population model structure and parameter values and uncertainty separately for every component of the model. This flexibility makes the modeling tool potentially applicable to any fish species; however, the flexibility inherent in this modeling tool makes it possible for the user to obtain spurious outputs. The value and reliability of the model outputs are only as good as the model inputs. Using this modeling tool with improper or inaccurate parameter values, or for species for which the structure of the model is inappropriate, could lead to untenable management decisions. By facilitating fish population modeling, this modeling tool allows the user to evaluate a range of management options and implications. The goal of this modeling tool is to be a user-friendly modeling tool for developing fish population models useful to natural resource

Evaluating effects of fish stocking on amphibian populations in wilderness lakes

Treesearch

David S. Pilliod; Charles R. Peterson

2000-01-01

To balance wilderness lake use between recreational fisheries and protected habitat for native species, managers need to understand how stocking non-native predaceous fish affects amphibian populations within a landscape. The goal of this paper is to help managers design and conduct studies that will provide such information. Desirable study characteristics include...

CHARACTERIZING POPULATIONS OF THE ESTUARINE FISH FUNDULUS HETEROCLITUS INDIGENOUS TO SITES WITH DIFFERING ENVIRONMENTAL QUALITY

EPA Science Inventory

Populations of the non-migratory estuarine fish Fundulus heteroclitus were collected from New Bedford Harbor and distant clean sites to investigate whether indigenous populations have adapted genetically to the harbor's contamination. New Bedford Harbor, a major port in southe...

Master Middle Ware: A Tool to Integrate Water Resources and Fish Population Dynamics Models

NASA Astrophysics Data System (ADS)

Yi, S.; Sandoval Solis, S.; Thompson, L. C.; Kilduff, D. P.

2017-12-01

Linking models that investigate separate components of ecosystem processes has the potential to unify messages regarding management decisions by evaluating potential trade-offs in a cohesive framework. This project aimed to improve the ability of riparian resource managers to forecast future water availability conditions and resultant fish habitat suitability, in order to better inform their management decisions. To accomplish this goal, we developed a middleware tool that is capable of linking and overseeing the operations of two existing models, a water resource planning tool Water Evaluation and Planning (WEAP) model and a habitat-based fish population dynamics model (WEAPhish). First, we designed the Master Middle Ware (MMW) software in Visual Basic for Application® in one Excel® file that provided a familiar framework for both data input and output Second, MMW was used to link and jointly operate WEAP and WEAPhish, using Visual Basic Application (VBA) macros to implement system level calls to run the models. To demonstrate the utility of this approach, hydrological, biological, and middleware model components were developed for the Butte Creek basin. This tributary of the Sacramento River, California is managed for both hydropower and the persistence of a threatened population of spring-run Chinook salmon (Oncorhynchus tschawytscha). While we have demonstrated the use of MMW for a particular watershed and fish population, MMW can be customized for use with different rivers and fish populations, assuming basic data requirements are met. This model integration improves on ad hoc linkages for managing data transfer between software programs by providing a consistent, user-friendly, and familiar interface across different model implementations. Furthermore, the data-viewing capabilities of MMW facilitate the rapid interpretation of model results by hydrologists, fisheries biologists, and resource managers, in order to accelerate learning and management decision

Using Fish Population Metrics to Compare the Effects of Artificial Reef Density.

PubMed

Froehlich, Catheline Y M; Kline, Richard J

2015-01-01

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1-190 culverts. Abundances of adults and species evenness of juvenile populations differed between the years. Fish communities did not significantly differ among density categories; however, highest species richness and total abundances were observed at intermediate culvert densities and at natural reefs. Whereas the abundance of L. campechanus did not differ among density categories, mean total lengths of L. campechanus were greatest at the lower density. Our findings suggest that reefs should be deployed with intermediate patch density of 71-120 culverts in a 30-m radius to yield the highest fish abundances.

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.

Intervention analysis of power plant impact on fish populations

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

Madenjian, C.P.

1984-10-01

Intervention analysis was applied to 10 yr (years 1973-1982) of field fish abundance data at the D. C. Cook Nuclear Power Plant, southeastern Lake Michigan. Three log-transformed catch series, comprising monthly observations, were examined for each combination of two species (alewife, Alosa pseudoharenga, or yellow perch, Perca flavescens) and gear (trawl or gill net): catch at the plant discharged transect, catch at the reference transect, and the ratio of plant catch to reference catch. Time series separated by age groups were examined. Based on intervention analysis, no change in the abundance of fish populations could be attributed to plant operation.more » Additionally, a modification of the intervention analysis technique was applied to investigate trends in abundance at both the plant discharge and reference transects. Significant declines were detected for abundance of alewife adults at both of the transects. Results of the trend analysis support the contention that the alewives have undergone a lakewide decrease in abundance during the 1970s.« less

Framework for Evaluating Habitat Restoration Success with Respect to Fish Habitat- and Population-related Beneficial Use Impairments

EPA Science Inventory

A major challenge of evaluating restoration progress is establishing a cause-effect relationship between observed changes in fish abundance and ongoing aquatic habitat restoration. Since 1979, fish populations within the St. Louis River Area of Concern, which were severely degrad...

Fish population genetic structure shaped by hydroelectric power plants in the upper Rhine catchment.

PubMed

Gouskov, Alexandre; Reyes, Marta; Wirthner-Bitterlin, Lisa; Vorburger, Christoph

2016-02-01

The Rhine catchment in Switzerland has been transformed by a chain of hydroelectric power stations. We addressed the impact of fragmentation on the genetic structure of fish populations by focusing on the European chub (Squalius cephalus). This fish species is not stocked and copes well with altered habitats, enabling an assessment of the effects of fragmentation per se. Using microsatellites, we genotyped 2133 chub from 47 sites within the catchment fragmented by 37 hydroelectric power stations, two weirs and the Rhine Falls. The shallow genetic population structure reflected drainage topology and was affected significantly by barriers to migration. The effect of power stations equipped with fishpasses on genetic differentiation was detectable, albeit weaker than that of man-made barriers without fishpasses. The Rhine Falls as the only long-standing natural obstacle (formed 14 000 to 17 000 years ago) also had a strong effect. Man-made barriers also exacerbated the upstream decrease in allelic diversity in the catchment, particularly when lacking fishpasses. Thus, existing fishpasses do have the desired effect of mitigating fragmentation, but barriers still reduce population connectivity in a fish that traverses fishpasses better than many other species. Less mobile species are likely to be affected more severely.

Evidence of population resistance to extreme low flows in a fluvial-dependent fish species

USGS Publications Warehouse

Katz, Rachel A.; Freeman, Mary C.

2015-01-01

Extreme low streamflows are natural disturbances to aquatic populations. Species in naturally intermittent streams display adaptations that enhance persistence during extreme events; however, the fate of populations in perennial streams during unprecedented low-flow periods is not well-understood. Biota requiring swift-flowing habitats may be especially vulnerable to flow reductions. We estimated the abundance and local survival of a native fluvial-dependent fish species (Etheostoma inscriptum) across 5 years encompassing historic low flows in a sixth-order southeastern USA perennial river. Based on capturemark-recapture data, the study shoal may have acted as a refuge during severe drought, with increased young-of-the-year (YOY) recruitment and occasionally high adult immigration. Contrary to expectations, summer and autumn survival rates (30 days) were not strongly depressed during low-flow periods, despite 25%-80% reductions in monthly discharge. Instead, YOY survival increased with lower minimum discharge and in response to small rain events that increased low-flow variability. Age-1+ fish showed the opposite pattern, with survival decreasing in response to increasing low-flow variability. Results from this population dynamics study of a small fish in a perennial river suggest that fluvial-dependent species can be resistant to extreme flow reductions through enhanced YOY recruitment and high survival

Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin.

PubMed

Camargo, M; Giarrizzo, T; Isaac, V J

2015-08-01

This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing.

The use of tumors in wild populations of fish to assess ecosystem health

USGS Publications Warehouse

Baumann, Paul C.

1992-01-01

Evidence has linked toxicants in aquatic systems with cancer in fish and population level effects on species. Thus some types of tumors may be useful monitors of ecosystem health, at least as affected by genotoxins and promoters. However, tumors caused by purely genetic mechanisms or by virus would not be good indicators. Only neoplasms which have chemicals as a portion of their etiology (either as initiators or promoters) would be useful in assessing ecosystem health. Lesions which may fit these criteria include liver neoplasms (both biliary and hepatic) and skin lesions in a variety of primarily benthic fishes, and neural lesions in various drum species and in butterfly fish species. Two studies purporting to demonstrate a lack of tumors in fish from polluted areas have been reexamined and found either to have insufficient data on vulnerable species or to actually support a tumor-pollution linkage. Thus certain lesions in vulnerable species or species groups may serve as a mechanism to assess one facet of ecosystem health.

Biomarkers in Natural Fish Populations Indicate Adverse Biological Effects of Offshore Oil Production

PubMed Central

Balk, Lennart; Hylland, Ketil; Hansson, Tomas; Berntssen, Marc H. G.; Beyer, Jonny; Jonsson, Grete; Melbye, Alf; Grung, Merete; Torstensen, Bente E.; Børseth, Jan Fredrik; Skarphedinsdottir, Halldora; Klungsøyr, Jarle

2011-01-01

Background Despite the growing awareness of the necessity of a sustainable development, the global economy continues to depend largely on the consumption of non-renewable energy resources. One such energy resource is fossil oil extracted from the seabed at offshore oil platforms. This type of oil production causes continuous environmental pollution from drilling waste, discharge of large amounts of produced water, and accidental spills. Methods and principal findings Samples from natural populations of haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) in two North Sea areas with extensive oil production were investigated. Exposure to and uptake of polycyclic aromatic hydrocarbons (PAHs) were demonstrated, and biomarker analyses revealed adverse biological effects, including induction of biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity. Genotoxicity was reflected by a hepatic DNA adduct pattern typical for exposure to a mixture of PAHs. Control material was collected from a North Sea area without oil production and from remote Icelandic waters. The difference between the two control areas indicates significant background pollution in the North Sea. Conclusion It is most remarkable to obtain biomarker responses in natural fish populations in the open sea that are similar to the biomarker responses in fish from highly polluted areas close to a point source. Risk assessment of various threats to the marine fish populations in the North Sea, such as overfishing, global warming, and eutrophication, should also take into account the ecologically relevant impact of offshore oil production. PMID:21625421

Biomarkers in natural fish populations indicate adverse biological effects of offshore oil production.

PubMed

Balk, Lennart; Hylland, Ketil; Hansson, Tomas; Berntssen, Marc H G; Beyer, Jonny; Jonsson, Grete; Melbye, Alf; Grung, Merete; Torstensen, Bente E; Børseth, Jan Fredrik; Skarphedinsdottir, Halldora; Klungsøyr, Jarle

2011-01-01

Despite the growing awareness of the necessity of a sustainable development, the global economy continues to depend largely on the consumption of non-renewable energy resources. One such energy resource is fossil oil extracted from the seabed at offshore oil platforms. This type of oil production causes continuous environmental pollution from drilling waste, discharge of large amounts of produced water, and accidental spills. Samples from natural populations of haddock (Melanogrammus aeglefinus) and Atlantic cod (Gadus morhua) in two North Sea areas with extensive oil production were investigated. Exposure to and uptake of polycyclic aromatic hydrocarbons (PAHs) were demonstrated, and biomarker analyses revealed adverse biological effects, including induction of biotransformation enzymes, oxidative stress, altered fatty acid composition, and genotoxicity. Genotoxicity was reflected by a hepatic DNA adduct pattern typical for exposure to a mixture of PAHs. Control material was collected from a North Sea area without oil production and from remote Icelandic waters. The difference between the two control areas indicates significant background pollution in the North Sea. It is most remarkable to obtain biomarker responses in natural fish populations in the open sea that are similar to the biomarker responses in fish from highly polluted areas close to a point source. Risk assessment of various threats to the marine fish populations in the North Sea, such as overfishing, global warming, and eutrophication, should also take into account the ecologically relevant impact of offshore oil production.

Energetic and ecological constraints on population density of reef fishes.

PubMed

Barneche, D R; Kulbicki, M; Floeter, S R; Friedlander, A M; Allen, A P

2016-01-27

Population ecology has classically focused on pairwise species interactions, hindering the description of general patterns and processes of population abundance at large spatial scales. Here we use the metabolic theory of ecology as a framework to formulate and test a model that yields predictions linking population density to the physiological constraints of body size and temperature on individual metabolism, and the ecological constraints of trophic structure and species richness on energy partitioning among species. Our model was tested by applying Bayesian quantile regression to a comprehensive reef-fish community database, from which we extracted density data for 5609 populations spread across 49 sites around the world. Our results indicate that population density declines markedly with increases in community species richness and that, after accounting for richness, energetic constraints are manifested most strongly for the most abundant species, which generally are of small body size and occupy lower trophic groups. Overall, our findings suggest that, at the global scale, factors associated with community species richness are the major drivers of variation in population density. Given that populations of species-rich tropical systems exhibit markedly lower maximum densities, they may be particularly susceptible to stochastic extinction. © 2016 The Author(s).

Energetic and ecological constraints on population density of reef fishes

PubMed Central

Barneche, D. R.; Kulbicki, M.; Floeter, S. R.; Friedlander, A. M.; Allen, A. P.

2016-01-01

Population ecology has classically focused on pairwise species interactions, hindering the description of general patterns and processes of population abundance at large spatial scales. Here we use the metabolic theory of ecology as a framework to formulate and test a model that yields predictions linking population density to the physiological constraints of body size and temperature on individual metabolism, and the ecological constraints of trophic structure and species richness on energy partitioning among species. Our model was tested by applying Bayesian quantile regression to a comprehensive reef-fish community database, from which we extracted density data for 5609 populations spread across 49 sites around the world. Our results indicate that population density declines markedly with increases in community species richness and that, after accounting for richness, energetic constraints are manifested most strongly for the most abundant species, which generally are of small body size and occupy lower trophic groups. Overall, our findings suggest that, at the global scale, factors associated with community species richness are the major drivers of variation in population density. Given that populations of species-rich tropical systems exhibit markedly lower maximum densities, they may be particularly susceptible to stochastic extinction. PMID:26791611

Complex small pelagic fish population patterns arising from individual behavioral responses to their environment

NASA Astrophysics Data System (ADS)

Brochier, Timothée; Auger, Pierre-Amaël; Pecquerie, Laure; Machu, Eric; Capet, Xavier; Thiaw, Modou; Mbaye, Baye Cheikh; Braham, Cheikh-Baye; Ettahiri, Omar; Charouki, Najib; Sène, Ousseynou Ndaw; Werner, Francisco; Brehmer, Patrice

2018-05-01

Small pelagic fish (SPF) species are heavily exploited in eastern boundary upwelling systems (EBUS) as their transformation products are increasingly used in the world's food chain. Management relies on regular monitoring, but there is a lack of robust theories for the emergence of the populations' traits and their evolution in highly variable environments. This work aims to address existing knowledge gaps by combining physical and biogeochemical modelling with an individual life-cycle based model applied to round sardinella (Sardinella aurita) off northwest Africa, a key species for regional food security. Our approach focused on the processes responsible for seasonal migrations, spatio-temporal size-structure, and interannual biomass fluctuations. Emergence of preferred habitat resulted from interactions between natal homing behavior and environmental variability that impacts early life stages. Exploration of the environment by the fishes was determined by swimming capabilities, mesoscale to regional habitat structure, and horizontal currents. Fish spatio-temporal abundance variability emerged from a complex combination of distinct life-history traits. An alongshore gradient in fish size distributions is reported and validated by in situ measurements. New insights into population structure are provided, within an area where the species is abundant year-round (Mauritania) and with latitudinal migrations of variable (300-1200 km) amplitude. Interannual biomass fluctuations were linked to modulations of fish recruitment over the Sahara Bank driven by variability in alongshore current intensity. The identified processes constitute an analytical framework that can be implemented in other EBUS and used to explore impacts of regional climate change on SPF.

Using Fish Population Metrics to Compare the Effects of Artificial Reef Density

PubMed Central

2015-01-01

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1–190 culverts. Abundances of adults and species evenness of juvenile populations differed between the years. Fish communities did not significantly differ among density categories; however, highest species richness and total abundances were observed at intermediate culvert densities and at natural reefs. Whereas the abundance of L. campechanus did not differ among density categories, mean total lengths of L. campechanus were greatest at the lower density. Our findings suggest that reefs should be deployed with intermediate patch density of 71–120 culverts in a 30-m radius to yield the highest fish abundances. PMID:26422472

Interactions Between the Cross-Shore Structure of Small Pelagic Fish Population, Offshore Industrial Fisheries and Near Shore Artisanal Fisheries: A Mathematical Approach.

PubMed

Mchich, Rachid; Brochier, Timothée; Auger, Pierre; Brehmer, Patrice

2016-12-01

This work presents a mathematical model describing the interactions between the cross-shore structure of small pelagic fish population an their exploitation by coastal and offshore fisheries. The complete model is a system of seven ODE's governing three stocks of small pelagic fish population moving and growing between three zones. Two types of fishing fleets are inter-acting with the fish population, industrial boats, constrained to offshore area, and artisanal boats, operating from the shore. Two time scales were considered and we use aggregation methods that allow us to reduce the dimension of the model and to obtain an aggregated model, which is a four dimension one. The analysis of the aggregated model is performed. We discuss the possible equilibriums and their meaning in terms of fishery management. An interesting equilibrium state can be obtained for which we can expect coexistence and a stable equilibrium state between fish stocks and fishing efforts. Some identification parameters are also given in the discussion part of the model.

Impacts of golden alga Prymnesium parvum on fish populations in reservoirs of the upper Colorado River and Brazos River basins, Texas

USGS Publications Warehouse

VanLandeghem, Matthew M.; Farooqi, Mukhtar; Farquhar, B.; Patino, Reynaldo

2013-01-01

Several reservoirs in the upper Colorado River and Brazos River basins in Texas have experienced toxic blooms of golden alga Prymnesium parvum and associated fish kills since 2001. There is a paucity of information, however, regarding the population-level effects of such kills in large reservoirs, species-specific resistance to or recovery from kills, or potential differences in the patterns of impacts among basins. We used multiple before-after, control-impact analysis to determine whether repeated golden alga blooms have led to declines in the relative abundance and size structure of fish populations. Sustained declines were noted for 9 of 12 fish species surveyed in the upper Colorado River, whereas only one of eight species was impacted by golden alga in the Brazos River. In the upper Colorado River, White Bass Morone chrysops, White Crappie Pomoxis annularis, Largemouth Bass Micropterus salmoides, Bluegill Lepomis macrochirus, River Carpsucker Carpiodes carpio, Freshwater Drum Aplodinotus grunniens, Channel Catfish Ictalurus punctatus, Flathead Catfish Pylodictis olivaris, and Blue Catfish I. furcatus exhibited sustained declines in relative abundance, size structure, or both; Gizzard Shad Dorosoma cepedianum, Longnose Gar Lepisosteus osseus, and Common Carp Cyprinus carpio did not exhibit those declines. In the Brazos River, only the relative abundance of Blue Catfish was impacted. Overall, toxic golden alga blooms can negatively impact fish populations over the long-term, but the patterns of impact can vary considerably among river basins and species. In the Brazos River, populations of most fish species appear to be healthy, suggesting a positive angling outlook for this basin. In the upper Colorado River, fish populations have been severely impacted, and angling opportunities have been reduced. Basin-specific management plans aimed at improving water quality and quantity will likely reduce bloom intensity and allow recovery of fish populations to the

Connectivity of microbial populations in coral reef environments: microbiomes of sediment, fish and water

NASA Astrophysics Data System (ADS)

Biddle, J.; Leon, Z. R.; McCargar, M.; Drew, J.

2016-12-01

The benthic environments of coral reefs are heavily shaped by physiochemical factors, but also the ecological interactions of the animals and plants in the reef ecosystem. Microbial populations may be shared between the ecosystem of sediments, seagrasses and reef fish, however it is unknown to what degree. We investigated the potential connections between the microbiomes of sediments, seagrass blades and roots (Syringodium isoetifolium), Surgeonfish (A. nigricauda, Acanthurinae sp. unknown, C. striatus) and Parrotfish (C. spinidens) guts in reef areas of Fiji. We contrasted these with sediment samples from the Florida Keys and ocean water microbiomes from the Atlantic, Pacific and Indian Oceans. In general, we see a higher diversity of sediment microbial communities in Fiji compared to the Florida Keys. However, many of the same taxa are shared in these chemically similar environments, whereas the ocean water environments are completely distinct with few overlapping groups. We were able to show connectivity of a core microbiome between seagrass, fish and sediments in Fiji, including identifying a potential environmental reservoir of a surgeonfish symbiont, Epulopiscum. Finally, we show that fish guts have different microbial populations from crop to hindgut, and that microbial populations differ based on food source. The connection of these ecosystems suggest that the total microbiome of these environments may vary as their animal inhabitants shift in a changing ocean.

Fishing degrades size structure of coral reef fish communities.

PubMed

Robinson, James P W; Williams, Ivor D; Edwards, Andrew M; McPherson, Jana; Yeager, Lauren; Vigliola, Laurent; Brainard, Russell E; Baum, Julia K

2017-03-01

Fishing pressure on coral reef ecosystems has been frequently linked to reductions of large fishes and reef fish biomass. Associated impacts on overall community structure are, however, less clear. In size-structured aquatic ecosystems, fishing impacts are commonly quantified using size spectra, which describe the distribution of individual body sizes within a community. We examined the size spectra and biomass of coral reef fish communities at 38 US-affiliated Pacific islands that ranged in human presence from near pristine to human population centers. Size spectra 'steepened' steadily with increasing human population and proximity to market due to a reduction in the relative biomass of large fishes and an increase in the dominance of small fishes. Reef fish biomass was substantially lower on inhabited islands than uninhabited ones, even at inhabited islands with the lowest levels of human presence. We found that on populated islands size spectra exponents decreased (analogous to size spectra steepening) linearly with declining biomass, whereas on uninhabited islands there was no relationship. Size spectra were steeper in regions of low sea surface temperature but were insensitive to variation in other environmental and geomorphic covariates. In contrast, reef fish biomass was highly sensitive to oceanographic conditions, being influenced by both oceanic productivity and sea surface temperature. Our results suggest that community size structure may be a more robust indicator than fish biomass to increasing human presence and that size spectra are reliable indicators of exploitation impacts across regions of different fish community compositions, environmental drivers, and fisheries types. Size-based approaches that link directly to functional properties of fish communities, and are relatively insensitive to abiotic variation across biogeographic regions, offer great potential for developing our understanding of fishing impacts in coral reef ecosystems. © 2016

Use of a storm water retention system for conservation of regionally endangered fishes

USGS Publications Warehouse

Schaeffer, Jeffrey S.; Bland, James K.; Janssen, John

2012-01-01

Maintaining aquatic biodiversity in urban or suburban areas can be problematic because urban landscapes can be nearly devoid of aquatic habitats other than engineered basins for storm water management. These areas are usually of questionable value for fish, but we examined a case study in which five regionally imperiled fish species were reintroduced into an artificial storm water detention pond and subsequently thrived. Although not a formal experiment, postintroduction survey data suggested that three of the five species maintained high population densities for 10 years after initial stocking, and two persisted in lower numbers. Success was likely due to a combination of unique design features and prior habitat preparation that resulted in clear water conditions that supported dense vegetation. Stocked fish persisted despite occasional bouts of low dissolved oxygen and increased chloride levels resulting from road salt application within the watershed. Transplanted fish served as a source population for both research and further reintroduction experiments. We suggest that, for some fish species, habitat preservation has a middle ground between natural habitats and completely artificial environments that require constant husbandry and that storm water systems could be used to create engineered sanctuaries within the human landscape that have many potential benefits for both humans and fish.

Potential population and assemblage influences of non-native trout on native nongame fish in Nebraska headwater streams

USGS Publications Warehouse

Turek, Kelly C.; Pegg, Mark A.; Pope, Kevin L.; Schainost, Steve

2014-01-01

Non-native trout are currently stocked to support recreational fisheries in headwater streams throughout Nebraska. The influence of non-native trout introductions on native fish populations and their role in structuring fish assemblages in these systems is unknown. The objectives of this study were to determine (i) if the size structure or relative abundance of native fish differs in the presence and absence of non-native trout, (ii) if native fish-assemblage structure differs in the presence and absence of non-native trout and (iii) if native fish-assemblage structure differs across a gradient in abundances of non-native trout. Longnose dace Rhinichthys cataractae were larger in the presence of brown trout Salmo trutta and smaller in the presence of rainbow trout Oncorhynchus mykiss compared to sites without trout. There was also a greater proportion of larger white suckers Catostomus commersonii in the presence of brown trout. Creek chub Semotilus atromaculatus and fathead minnow Pimephales promelas size structures were similar in the presence and absence of trout. Relative abundances of longnose dace, white sucker, creek chub and fathead minnow were similar in the presence and absence of trout, but there was greater distinction in native fish-assemblage structure between sites with trout compared to sites without trout as trout abundances increased. These results suggest increased risk to native fish assemblages in sites with high abundances of trout. However, more research is needed to determine the role of non-native trout in structuring native fish assemblages in streams, and the mechanisms through which introduced trout may influence native fish populations.

VARIATION IN RESPONSIVENESS TO CONTAMINANTS IN WILD POPULATIONS OF ESTUARINE FISH, FUNDULUS HETERCLITUS

EPA Science Inventory

Populations of the non-migratory estuarine fish species Fundulus heteroclitus indigenous to a PCB-contaminated Superfund site (New Bedford Harbor, MA, USA) are markedly less sensitive to the toxic effects of local contaminants than those from a reference site. We characterized th...

Comparing Climate Change and Species Invasions as Drivers of Coldwater Fish Population Extirpations

PubMed Central

Sharma, Sapna; Vander Zanden, M. Jake; Magnuson, John J.; Lyons, John

2011-01-01

Species are influenced by multiple environmental stressors acting simultaneously. Our objective was to compare the expected effects of climate change and invasion of non-indigenous rainbow smelt (Osmerus mordax) on cisco (Coregonus artedii) population extirpations at a regional level. We assembled a database of over 13,000 lakes in Wisconsin, USA, summarising fish occurrence, lake morphology, water chemistry, and climate. We used A1, A2, and B1 scenarios from the Intergovernmental Panel on Climate Change (IPCC) of future temperature conditions for 15 general circulation models in 2046–2065 and 2081–2100 totalling 78 projections. Logistic regression indicated that cisco tended to occur in cooler, larger, and deeper lakes. Depending upon the amount of warming, 25–70% of cisco populations are predicted to be extirpated by 2100. In addition, cisco are influenced by the invasion of rainbow smelt, which prey on young cisco. Projecting current estimates of rainbow smelt spread and impact into the future will result in the extirpation of about 1% of cisco populations by 2100 in Wisconsin. Overall, the effect of climate change is expected to overshadow that of species invasion as a driver of coldwater fish population extirpations. Our results highlight the potentially dominant role of climate change as a driver of biotic change. PMID:21860661

Comparing climate change and species invasions as drivers of coldwater fish population extirpations.

PubMed

Sharma, Sapna; Vander Zanden, M Jake; Magnuson, John J; Lyons, John

2011-01-01

Species are influenced by multiple environmental stressors acting simultaneously. Our objective was to compare the expected effects of climate change and invasion of non-indigenous rainbow smelt (Osmerus mordax) on cisco (Coregonus artedii) population extirpations at a regional level. We assembled a database of over 13,000 lakes in Wisconsin, USA, summarising fish occurrence, lake morphology, water chemistry, and climate. We used A1, A2, and B1 scenarios from the Intergovernmental Panel on Climate Change (IPCC) of future temperature conditions for 15 general circulation models in 2046-2065 and 2081-2100 totalling 78 projections. Logistic regression indicated that cisco tended to occur in cooler, larger, and deeper lakes. Depending upon the amount of warming, 25-70% of cisco populations are predicted to be extirpated by 2100. In addition, cisco are influenced by the invasion of rainbow smelt, which prey on young cisco. Projecting current estimates of rainbow smelt spread and impact into the future will result in the extirpation of about 1% of cisco populations by 2100 in Wisconsin. Overall, the effect of climate change is expected to overshadow that of species invasion as a driver of coldwater fish population extirpations. Our results highlight the potentially dominant role of climate change as a driver of biotic change.

Modeling the fish community population dynamics and forecasting the eradication success of an exotic fish from an alpine stream

USGS Publications Warehouse

Laplanche, Christophe; Elger, Arnaud; Santoul, Frédéric; Thiede, Gary P.; Budy, Phaedra

2018-01-01

Management actions aimed at eradicating exotic fish species from riverine ecosystems can be better informed by forecasting abilities of mechanistic models. We illustrate this point with an example of the Logan River, Utah, originally populated with endemic cutthroat trout (Oncorhynchus clarkii utah), which compete with exotic brown trout (Salmo trutta). The coexistence equilibrium was disrupted by a large scale, experimental removal of the exotic species in 2009–2011 (on average, 8.2% of the stock each year), followed by an increase in the density of the native species. We built a spatially-explicit, reaction-diffusion model encompassing four key processes: population growth in heterogeneous habitat, competition, dispersal, and a management action. We calibrated the model with detailed long-term monitoring data (2001–2016) collected along the 35.4-km long river main channel. Our model, although simple, did a remarkable job reproducing the system steady state prior to the management action. Insights gained from the model independent predictions are consistent with available knowledge and indicate that the exotic species is more competitive; however, the native species still occupies more favorable habitat upstream. Dynamic runs of the model also recreated the observed increase of the native species following the management action. The model can simulate two possible distinct long-term outcomes: recovery or eradication of the exotic species. The processing of available knowledge using Bayesian methods allowed us to conclude that the chance for eradication of the invader was low at the beginning of the experimental removal (0.7% in 2009) and increased (20.5% in 2016) by using more recent monitoring data. We show that accessible mathematical and numerical tools can provide highly informative insights for managers (e.g., outcome of their conservation actions), identify knowledge gaps, and provide testable theory for researchers.

Fish Commoditization: Sustainability Strategies to Protect Living Fish

ERIC Educational Resources Information Center

Lam, Mimi E.; Pitcher, Tony J.

2012-01-01

The impacts of early fishing on aquatic ecosystems were minimal, as primitive technologies were used to harvest fish primarily for food. As fishing technology grew more sophisticated and human populations dispersed and expanded, local economies transitioned from subsistence to barter and trade. Expanded trade networks and mercantilization led to…

Response of fish populations to natural channel design restoration in streams of the Catskill Mountains, New York

USGS Publications Warehouse

Baldigo, Barry P.; Warren, D.R.; Ernst, A.G.; Mulvihill, C.I.

2008-01-01

Many streams and rivers throughout North America have been extensively straightened, widened, and hardened since the middle 1800s, but related effects on aquatic ecosystems have seldom been monitored, described, or published. Beginning in the early 1990s, reach-level restoration efforts began to base projects on natural channel design (NCD) techniques and Rosgen's (1994b, 1996) river classification system in an effort to duplicate or mimic stable reference reach geomorphology. Four reaches in three streams of the Catskill Mountains, New York, were restored from 2000 to 2002 using NCD techniques to decrease bed and bank erosion rates, decrease sediment loads, and improve water quality. The effects of restoration on the health of fish assemblages were assessed through a before-after, control-impact (BACI) study design to quantify the net changes in population and community indices at treatment reaches relative to index changes at unaltered reference reaches from 1999 to 2004. After restoration, community richness and biomass at treatment reaches increased by more than one-third. Changes in fish communities were caused mainly by shifts in dominant species populations; fish community biomass and total fish abundance were generally dominated by daces or daces and sculpins before restoration and by one or more salmonid species after restoration. Density and biomass of eastern blacknose dace Rhinichthys atratulus, longnose dace R. cataractae, and slimy sculpin Cottus cognatus did not change appreciably, whereas net salmonid density and biomass increased substantially after restoration. These changes were driven primarily by large increases in populations of brown trout Salmo trutta. The findings demonstrate that the structure, function, and ultimately the health of resident fish populations and communities can be improved, at least over the short term, through NCD restoration in perturbed streams of the Catskill Mountains. ?? Copyright by the American Fisheries Society

A model describing the effect of sex-reversed YY fish in an established wild population: The use of a Trojan Y chromosome to cause extinction of an introduced exotic species.

PubMed

Gutierrez, Juan B; Teem, John L

2006-07-21

A novel means of inducing extinction of an exotic fish population is proposed using a genetic approach to shift the ratio of male to females within a population. In the proposed strategy, sex-reversed fish containing two Y chromosomes are introduced into a normal fish population. These YY fish result in the production of a disproportionate number of male fish in subsequent generations. Mathematical modeling of the system following introduction of YY fish at a constant rate reveals that female fish decline in numbers over time, leading to eventual extinction of the population.

Indicators of fishing mortality on reef-shark populations in the world's first shark sanctuary: the need for surveillance and enforcement

NASA Astrophysics Data System (ADS)

Vianna, Gabriel M. S.; Meekan, Mark G.; Ruppert, Jonathan L. W.; Bornovski, Tova H.; Meeuwig, Jessica J.

2016-09-01

Shark sanctuaries are promoted as a management tool to achieve conservation goals following global declines of shark populations. We assessed the status of reef-shark populations and indicators of fishing pressure across the world's first shark sanctuary in Palau. Using underwater surveys and stereophotogrammetry, we documented large differences in abundance and size structure of shark populations across the sanctuary, with a strong negative relationship between shark densities and derelict fishing gear on reefs. Densities of 10.9 ± 4.7 (mean ± SE) sharks ha-1 occurred on reefs adjacent to the most populated islands of Palau, contrasting with lower densities of 1.6 ± 0.8 sharks ha-1 on remote uninhabited reefs, where surveillance and enforcement was limited. Our observations suggest that fishing still remains a major factor structuring shark populations in Palau, demonstrating that there is an urgent need for better enforcement and surveillance that targets both illegal and licensed commercial fisheries to provide effective protection for sharks within the sanctuary.

Biological Entanglement-Like Effect After Communication of Fish Prior to X-Ray Exposure.

PubMed

Mothersill, Carmel; Smith, Richard; Wang, Jiaxi; Rusin, Andrej; Fernandez-Palomo, Cris; Fazzari, Jennifer; Seymour, Colin

2018-01-01

The phenomenon by which irradiated organisms including cells in vitro communicate with unirradiated neighbors is well established in biology as the radiation-induced bystander effect (RIBE). Generally, the purpose of this communication is thought to be protective and adaptive, reflecting a highly conserved evolutionary mechanism enabling rapid adjustment to stressors in the environment. Stressors known to induce the effect were recently shown to include chemicals and even pathological agents. The mechanism is unknown but our group has evidence that physical signals such as biophotons acting on cellular photoreceptors may be implicated. This raises the question of whether quantum biological processes may occur as have been demonstrated in plant photosynthesis. To test this hypothesis, we decided to see whether any form of entanglement was operational in the system. Fish from 2 completely separate locations were allowed to meet for 2 hours either before or after which fish from 1 location only (group A fish) were irradiated. The results confirm RIBE signal production in both skin and gill of fish, meeting both before and after irradiation of group A fish. The proteomic analysis revealed that direct irradiation resulted in pro-tumorigenic proteomic responses in rainbow trout. However, communication from these irradiated fish, both before and after they had been exposed to a 0.5 Gy X-ray dose, resulted in largely beneficial proteomic responses in completely nonirradiated trout. The results suggest that some form of anticipation of a stressor may occur leading to a preconditioning effect or temporally displaced awareness after the fish become entangled.

Within and between Population Variation in Epidermal Club Cell Investment in a Freshwater Prey Fish: A Cautionary Tale for Evolutionary Ecologists

PubMed Central

Manek, Aditya K.; Ferrari, Maud C. O.; Pollock, Robyn J.; Vicente, Daniel; Weber, Lynn P.; Chivers, Douglas P.

2013-01-01

Many prey fishes possess large club cells in their epidermis. The role of these cells has garnered considerable attention from evolutionary ecologists. These cells likely form part of the innate immune system of fishes, however, they also have an alarm function, releasing chemical cues that serve to warn nearby conspecifics of danger. Experiments aimed at understanding the selection pressures leading to the evolution of these cells have been hampered by a surprisingly large intraspecific variation in epidermal club cell (ECC) investment. The goal of our current work was to explore the magnitude and nature of this variation in ECC investment. In a field survey, we documented large differences in ECC investment both within and between several populations of minnows. We then tested whether we could experimentally reduce variation in mean ECC number by raising fish under standard laboratory conditions for 4 weeks. Fish from different populations responded very differently to being held under standard laboratory conditions; some populations showed an increase in ECC investment while others remained unchanged. More importantly, we found some evidence that we could reduce within population variation in ECC investment through time, but could not reduce among-population variation in mean ECC investment. Given the large variation we observed in wild fish and our limited ability to converge mean cell number by holding the fish under standard conditions, we caution that future studies may be hard pressed to find subtle effects of various experimental manipulations; this will make elucidating the selection pressures leading to the evolution of the cells challenging. PMID:23469175

Levels of persistent organic pollutants (POPs) in a coastal northern Norwegian population with high fish-liver intake.

PubMed

Sandanger, T M; Brustad, M; Sandau, C D; Lund, E

2006-05-01

Recent research has again raised the issue regarding the potential health effects of long term exposure to persistent organic pollutants (POPs) in the context of a risk-benefit analysis. There remains clear evidence of the beneficial effects of fish consumption on public health and in particular fatty fish with its essential fatty acids. In addition to providing fatty acids, fish fat constitutes an essential source to vitamin D for the northern Norwegian population. Norwegian Food Control Authorities have recommended that children and women of childbearing age should not consume fish liver due to the risk associated with high intake of POPs. The aim of this study was to assess the influence of fish liver intake on the levels of PCBs and chlorinated pesticides in a rural coastal community (n = 31) in northern Norway, applying a cross-sectional design. The geometric mean plasma levels of sum of PCBs (14 congeners) and p,p'-DDE was found to be 558 microg kg(-1) lipids and 179 microg kg(-1) lipids, respectively. These levels were not significantly affected by the reported intake of fish liver, when age and gender were considered. Age in particular, but also gender were significant predictors for most compounds. When merging the dataset with an urban population with considerable lower intake of fish liver, the intake of cod liver still did not significantly affect the levels of PCBs and p,p'-DDE when adjusted for age and gender. Age and gender remain the strongest predictors of plasma levels of POPs in this study whereas fish liver intake was not significantly associated with the POPs.

Population characteristics of channel catfish near the northern edge of their distribution: implications for management

USGS Publications Warehouse

Carter-Lynn, K. P.; Quist, Michael C.

2015-01-01

Channel catfish, Ictalurus punctatus (Rafinesque), populations in six lakes in northern Idaho, USA, were sampled to describe their population characteristics. During the summers of 2011 and 2012, 4864 channel catfish were sampled. Channel catfish populations had low to moderate catch rates, and length structure was dominated by fish <400 mm. Channel catfish were in good body condition. All populations were maintained by stocking age-1 or age-2 fish. Growth of fish reared in thermally enriched environments prior to stocking was fast compared to other North American channel catfish populations. After stocking, growth of channel catfish declined rapidly. Once stocked, cold water temperatures, prey resources and (or) genetic capabilities limited growth. Total annual mortality of age 2 and older channel catfish was generally <40%. Tag returns indicated that angler exploitation was low, varying from 0 to 43% among lakes. This research provides insight on factors regulating channel catfish population dynamics and highlights important considerations associated with their ecology and management.

Which Fish Should I Eat? Perspectives Influencing Fish Consumption Choices

PubMed Central

Choi, Anna L.; Karagas, Margaret R.; Mariën, Koenraad; Rheinberger, Christoph M.; Schoeny, Rita; Sunderland, Elsie; Korrick, Susan

2012-01-01

Background: Diverse perspectives have influenced fish consumption choices. Objectives: We summarized the issue of fish consumption choice from toxicological, nutritional, ecological, and economic points of view; identified areas of overlap and disagreement among these viewpoints; and reviewed effects of previous fish consumption advisories. Methods: We reviewed published scientific literature, public health guidelines, and advisories related to fish consumption, focusing on advisories targeted at U.S. populations. However, our conclusions apply to groups having similar fish consumption patterns. Discussion: There are many possible combinations of matters related to fish consumption, but few, if any, fish consumption patterns optimize all domains. Fish provides a rich source of protein and other nutrients, but because of contamination by methylmercury and other toxicants, higher fish intake often leads to greater toxicant exposure. Furthermore, stocks of wild fish are not adequate to meet the nutrient demands of the growing world population, and fish consumption choices also have a broad economic impact on the fishing industry. Most guidance does not account for ecological and economic impacts of different fish consumption choices. Conclusion: Despite the relative lack of information integrating the health, ecological, and economic impacts of different fish choices, clear and simple guidance is necessary to effect desired changes. Thus, more comprehensive advice can be developed to describe the multiple impacts of fish consumption. In addition, policy and fishery management inter-ventions will be necessary to ensure long-term availability of fish as an important source of human nutrition. PMID:22534056

LINKING HISTORICAL ORGANOCHLORINE EXPOSURES IN THE GREAT LAKES CAUSALLY TO MAJOR FISH POPULATION CHANGES

EPA Science Inventory

The Great Lakes of North America are large aquatic ecosystems that have been greatly impacted by human activities in the 20th century. Introduction of non-native species, both advertently and inadvertently; reduction in populations through commercial fishing; habitat alternation...

Phenotypic conversion of distinct muscle fiber populations to electrocytes in a weakly electric fish.

PubMed

Unguez, G A; Zakon, H H

1998-09-14

In most groups of electric fish, the electric organ (EO) derives from striated muscle cells that suppress many muscle phenotypic properties. This phenotypic conversion is recapitulated during regeneration of the tail in the weakly electric fish Sternopygus macrurus. Mature electrocytes, the cells of the electric organ, are considerably larger than the muscle fibers from which they derive, and it is not known whether this is a result of muscle fiber hypertrophy and/or fiber fusion. In this study, electron micrographs revealed fusion of differentiated muscle fibers during the formation of electrocytes. There was no evidence of hypertrophy of muscle fibers during their phenotypic conversion. Furthermore, although fish possess distinct muscle phenotypes, the extent to which each fiber population contributes to the formation of the EO has not been determined. By using myosin ATPase histochemistry and anti-myosin heavy chain (MHC) monoclonal antibodies (mAbs), different fiber types were identified in fascicles of muscle in the adult tail. Mature electrocytes were not stained by the ATPase reaction, nor were they labeled by any of the anti-MHC mAbs. In contrast, mature muscle fibers exhibited four staining patterns. The four fiber types were spatially arranged in distinct compartments with little intermixing; peripherally were two populations of type I fibers with small cross-sectional areas, whereas more centrally were two populations of type II fibers with larger cross-sectional areas. In 2- and 3-week regenerating blastema, three fiber types were clearly discerned. Most (> 95%) early-forming electrocytes had an MHC phenotype similar to that of type II fibers. In contrast, fusion among type I fibers was rare. Together, ultrastructural and immunohistochemical analyses revealed that the fusion of muscle fibers gives rise to electrocytes and that this fusion occurs primarily among the population of type II fibers in regenerating blastema.

Rising temperatures may drive fishing-induced selection of low-performance phenotypes

PubMed Central

Clark, Timothy D.; Messmer, Vanessa; Tobin, Andrew J.; Hoey, Andrew S.; Pratchett, Morgan S.

2017-01-01

Climate warming is likely to interact with other stressors to challenge the physiological capacities and survival of phenotypes within populations. This may be especially true for the billions of fishes per year that undergo vigorous exercise prior to escaping or being intentionally released from fishing gear. Using adult coral grouper (Plectropomus leopardus), an important fisheries species throughout the Indo-Pacific, we show that population-level survival following vigorous exercise is increasingly compromised as temperatures increase from current-day levels (100–67% survival at 24–30 °C) to those projected for the end of the century (42% survival at 33 °C). Intriguingly, we demonstrate that high-performance individuals take longer to recover to a resting metabolic state and subsequently have lower survival in warm water compared with conspecifics that exercise less vigorously. Moreover, we show that post-exercise mortality of high-performance phenotypes manifests after 3–13 d at the current summer maximum (30 °C), while mortality at 33 °C occurs within 1.8–14.9 h. We propose that wild populations in a warming climate may become skewed towards low-performance phenotypes with ramifications for predator-prey interactions and community dynamics. Our findings highlight the susceptibility of phenotypic diversity to fishing activities and demonstrate a mechanism that may contribute to fishing-induced evolution in the face of ongoing climate change. PMID:28094310

Fish and fire: Post-wildfire sediment dynamics and implications for the viability of trout populations

NASA Astrophysics Data System (ADS)

Murphy, B. P.; Czuba, J. A.; Belmont, P.; Budy, P.; Finch, C.

2017-12-01

Episodic events in steep landscapes, such as wildfire and mass wasting, contribute large pulses of sediment to rivers and can significantly alter the quality and connectivity of fish habitat. Understanding where these sediment inputs occur, how they are transported and processed through the watershed, and their geomorphic effect on the river network is critical to predicting the impact on ecological aquatic communities. The Tushar Mountains of southern Utah experienced a severe wildfire in 2010, resulting in numerous debris flows and the extirpation of trout populations. Following many years of habitat and ecological monitoring in the field, we have developed a modeling framework that links post-wildfire debris flows, fluvial sediment routing, and population ecology in order to evaluate the impact and response of trout to wildfire. First, using the Tushar topographic and wildfire parameters, as well as stochastic precipitation generation, we predict the post-wildfire debris flow probabilities and volumes of mainstem tributaries using the Cannon et al. [2010] model. This produces episodic hillslope sediment inputs, which are delivered to a fluvial sediment, river-network routing model (modified from Czuba et al. [2017]). In this updated model, sediment transport dynamics are driven by time-varying discharge associated with the stochastic precipitation generation, include multiple grain sizes (including gravel), use mixed-size transport equations (Wilcock & Crowe [2003]), and incorporate channel slope adjustments with aggradation and degradation. Finally, with the spatially explicit adjustments in channel bed elevation and grain size, we utilize a new population viability analysis (PVA) model to predict the impact and recovery of fish populations in response to these changes in habitat. Our model provides a generalizable framework for linking physical and ecological models and for evaluating the extirpation risk of isolated fish populations throughout the

Great Lakes prey fish populations: A cross-basin overview of status and trends in 2008

USGS Publications Warehouse

Gorman, Owen T.; Bunnell, David B.

2009-01-01

Assessments of prey fishes in the Great Lakes have been conducted annually since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. Prey fish assessments differ among lakes in the proportion of a lake covered, seasonal timing, bottom trawl gear used, sampling design, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique in one or more important aspects, a direct comparison of prey fish catches among lakes is problematic. All of the assessments, however, produce indices of abundance or biomass that can be standardized to facilitate comparisons of trends among lakes and to illustrate present status of the populations. We present indices of abundance for important prey fishes in the Great Lakes standardized to the highest value for a time series within each lake: cisco (Coregonus artedi), bloater (C. hoyi), rainbow smelt (Osmerus mordax), and alewife (Alosa pseudoharengus). We also provide indices for round goby (Neogobius melanostomus), an invasive fish presently spreading throughout the basin. Our intent is to provide a short, informal report emphasizing data presentation rather than synthesis; for this reason we intentionally avoid use of tables and cited references.For each lake, standardized relative indices for annual biomass and density estimates of important prey fishes were calculated as the fraction relative to the largest value observed in the times series. To determine whether basin-wide trends were apparent for each species, we first ranked standardized index values within each lake. When comparing ranked index values from three or more lakes, we calculated the Kendall coefficient of concordance (W), which can range from 0 (complete discordance or disagreement among trends) to 1 (complete concordance or agreement among trends). The P-value for W provides the probability of agreement across the lakes. When comparing ranked index values from two lakes, we calculated

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.

29 CFR 784.123 - Operations performed on fishing equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... fish trap frames on the shore immediately prior to the opening of the fishing season would be within... that the employment is, in practical effect, directly and necessarily a part of the fishing operations...

Movements and demography of spawning American Shad in the Penobscot River, Maine, prior to dam removal

USGS Publications Warehouse

Grote, Ann B.; Bailey, Michael M.; Zydlewski, Joseph D.

2014-01-01

We conducted a baseline study to better understand the migratory movements and age and spawning histories of American Shad Alosa sapidissima in the Penobscot River, Maine. The Penobscot River is currently undergoing a major dam removal project that is focused on restoring migratory connectivity and recovering diadromous fish populations including American Shad. This study addresses key data gaps for a previously unstudied native population of shad prior to restoration. A combination of radio- (n = 70) and acoustic telemetry (n = 14) was used to investigate the movements of migratory adult fish in 2010 and 2011. Scale-based analyses were used to assess spawner age and iteroparity. Radiotelemetry results indicated that few tagged fish (5–8%) approached the head-of-tide dam. Tagged fish exhibited three general patterns of movement in the accessible freshwater river habitat: use of the upper river reach, the lower river reach, or both. Mean freshwater residence time ranged from 9.1 to 14.0 d. Congregating fish were observed at two sites in the upper river reach and spawning activity was observed. Freshwater survival and survival to the estuary were at least 71%. This observed high survival was consistent with the estimated age and spawning histories of tracked fish, which indicated that 75–95% of the sampled fish were repeat spawners. Estimated age of adult migrants ranged from age 4 to age 9. Postspawning acoustic-tagged American Shad exhibited a series of prolonged upstream and downstream reversals upon entering the lower estuary. These movements have been previously unreported, and suggest that estuarine residency after spawning is important to osmoregulatory acclimatization for re-entry into salt water and the resumption of postspawning feeding activity.

Genetic structuring among silverside fish (Atherinella brasiliensis) populations from different Brazilian regions

NASA Astrophysics Data System (ADS)

da Silva Cortinhas, Maria Cristina; Kersanach, Ralf; Proietti, Maíra; Dumont, Luiz Felipe Cestari; D'Incao, Fernando; Lacerda, Ana Luzia F.; Prata, Pedro Sanmartin; Matoso, Daniele Aparecida; Noleto, Rafael Bueno; Ramsdorf, Wanessa; Boni, Talge Aiex; Prioli, Alberto José; Cestari, Marta Margarete

2016-09-01

Estuaries are dynamic environments, key for the survival of innumerous ecologically or economically important fish species. Among these species are Neotropical silversides (Atherinella brasiliensis), which are resident and abundant in Brazilian estuaries and used as a complementary source of income and food for local communities. To better understand silverside populations in Brazil, we evaluated the genetic diversity, structure and demography of fish sampled at six estuaries from the northeastern to the southern coast, using Random Amplified Polymorphic DNA and mitochondrial DNA (D-loop) markers. High haplotype diversities (h ranging from 0.75 to 0.99) were found in all populations except Carapebus, located in Southeast Brazil (h = 0.54). A total of 69 mtDNA haplotypes were found, with Itaparica (Northeast Brazil) and Carapebus presenting only exclusive haplotypes, while some were shared among populations in the South. Strong regional structure was observed, with very high differentiation between Itaparica and Carapebus, as well as among these two populations and the ones from the Southern region (Paranaguá, Conceição, Camacho and Patos). Among southern areas, low/moderate structure was detected. Most populations showed unimodal mismatch distributions indicating recent demographic expansion, while Carapebus presented a multimodal distribution characteristic of a stable or bottlenecked population. Times since possible population expansion were highest in Itaparica (32,500 ya) and Carapebus (29,540 ya), while in the Southern region longest time was observed at Conceição (25,540 ya) and shortest at Patos (9720 ya). In a general manner, haplotype diversities were directly related to times since population expansions; again, Carapebus was the exception, displaying long time since expansion but low diversity, possibly due to a recent bottleneck caused by the isolation and human impacts this lagoon is subject to. Isolation by Distance was significant for Itaparica

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

Testing animal-assisted cleaning prior to transplantation in coral reef restoration.

PubMed

Frias-Torres, Sarah; van de Geer, Casper

2015-01-01

Rearing coral fragments in nurseries and subsequent transplantation onto a degraded reef is a common approach for coral reef restoration. However, if barnacles and other biofouling organisms are not removed prior to transplantation, fish will dislodge newly cemented corals when feeding on biofouling organisms. This behavior can lead to an increase in diver time due to the need to reattach the corals. Thus, cleaning nurseries to remove biofouling organisms such as algae and invertebrates is necessary prior to transplantation, and this cleaning constitutes a significant time investment in a restoration project. We tested a novel biomimicry technique of animal-assisted cleaning on nursery corals prior to transplantation at a coral reef restoration site in Seychelles, Indian Ocean. To determine whether animal-assisted cleaning was possible, preliminary visual underwater surveys were performed to quantify the fish community at the study site. Then, cleaning stations consisting of nursery ropes carrying corals and biofouling organisms, set at 0.3 m, 2 m, 4 m, 6 m and 8 m from the seabed, were placed at both the transplantation (treatment) site and the nursery (control) site. Remote GoPro video cameras recorded fish feeding at the nursery ropes without human disturbance. A reef fish assemblage of 32 species from 4 trophic levels (18.8% herbivores, 18.8% omnivores, 59.3% secondary consumers and 3.1% carnivores) consumed 95% of the barnacles on the coral nursery ropes placed 0.3 m above the seabed. Using this cleaning station, we reduced coral dislodgement from 16% to zero. This cleaning station technique could be included as a step prior to coral transplantation worldwide on the basis of location-specific fish assemblages and during the early nursery phase of sexually produced juvenile corals.

Testing animal-assisted cleaning prior to transplantation in coral reef restoration

PubMed Central

van de Geer, Casper

2015-01-01

Rearing coral fragments in nurseries and subsequent transplantation onto a degraded reef is a common approach for coral reef restoration. However, if barnacles and other biofouling organisms are not removed prior to transplantation, fish will dislodge newly cemented corals when feeding on biofouling organisms. This behavior can lead to an increase in diver time due to the need to reattach the corals. Thus, cleaning nurseries to remove biofouling organisms such as algae and invertebrates is necessary prior to transplantation, and this cleaning constitutes a significant time investment in a restoration project. We tested a novel biomimicry technique of animal-assisted cleaning on nursery corals prior to transplantation at a coral reef restoration site in Seychelles, Indian Ocean. To determine whether animal-assisted cleaning was possible, preliminary visual underwater surveys were performed to quantify the fish community at the study site. Then, cleaning stations consisting of nursery ropes carrying corals and biofouling organisms, set at 0.3 m, 2 m, 4 m, 6 m and 8 m from the seabed, were placed at both the transplantation (treatment) site and the nursery (control) site. Remote GoPro video cameras recorded fish feeding at the nursery ropes without human disturbance. A reef fish assemblage of 32 species from 4 trophic levels (18.8% herbivores, 18.8% omnivores, 59.3% secondary consumers and 3.1% carnivores) consumed 95% of the barnacles on the coral nursery ropes placed 0.3 m above the seabed. Using this cleaning station, we reduced coral dislodgement from 16% to zero. This cleaning station technique could be included as a step prior to coral transplantation worldwide on the basis of location-specific fish assemblages and during the early nursery phase of sexually produced juvenile corals. PMID:26468440

Evaluation of marine subareas of Europe using life history parameters and trophic levels of selected fish populations.

PubMed

Jayasinghe, R P Prabath K; Amarasinghe, Upali S; Newton, Alice

2015-12-01

European marine waters include four regional seas that provide valuable ecosystem services to humans, including fish and other seafood. However, these marine environments are threatened by pressures from multiple anthropogenic activities and climate change. The European Marine Strategy Framework Directive (MSFD) was adopted in 2008 to achieve good environmental status (GEnS) in European Seas by year 2020, using an Ecosystem Approach. GEnS is to be assessed using 11 descriptors and up to 56 indicators. In the present analysis two descriptors namely "commercially exploited fish and shellfish populations" and "food webs" were used to evaluate the status of subareas of FAO 27 area. Data on life history parameters, trophic levels and fisheries related data of cod, haddock, saithe, herring, plaice, whiting, hake and sprat were obtained from the FishBase online database and advisory reports of International Council for the Exploration of the Sea (ICES). Subareas inhabited by r and K strategists were identified using interrelationships of life history parameters of commercially important fish stocks. Mean trophic level (MTL) of fish community each subarea was calculated and subareas with species of high and low trophic level were identified. The Fish in Balance (FiB) index was computed for each subarea and recent trends of FiB indices were analysed. The overall environmental status of each subarea was evaluated considering life history trends, MTL and FiB Index. The analysis showed that subareas I, II, V, VIII and IX were assessed as "good" whereas subareas III, IV, VI and VII were assessed as "poor". The subareas assessed as "good" were subject to lower environmental pressures, (less fishing pressure, less eutrophication and more water circulation), while the areas with "poor" environment experienced excessive fishing pressure, eutrophication and disturbed seabed. The evaluation was based on two qualitative descriptors ("commercially exploited fish and shellfish

Empirical assessment of fish introductions in a subtropical wetland: An evaluation of contrasting views

USGS Publications Warehouse

Trexler, J.C.; Loftus, W.F.; Jordan, F.; Lorenz, J.J.; Chick, J.H.; Kobza, Robert M.

2000-01-01

We summarized data from eight quantitative fish surveys conducted in southern Florida to evaluate the distribution and relative abundance of introduced fishes across a variety of habitats. These surveys encompassed marsh and canal habitats throughout most of the Everglades region, including the mangrove fringe of Florida Bay. Two studies provided systematically collected density information over a 20-year period, and documented the first local appearance of four introduced fishes based on their repeated absence in prior surveys. Those species displayed a pattern of rapid population growth followed by decline, then persistence at lower densities. Estuarine areas in the southern Everglades, characterized by natural tidal creeks surrounded by mangrove-dominated marshes, and canals held the largest introduced-fish populations. Introduced fishes were also common, at times exceeding 50% of the fish community, in solution holes that serve as dry-season refuges in short-hydroperiod rockland habitats of the eastern Everglades. Wet prairies and alligator ponds distant from canals generally held few individuals of introduced fishes. These patterns suggest that the introduced fishes in southern Florida at present may not be well-adapted to persist in freshwater marshes of the Everglades, possibly because of an interaction of periodic cold-temperature stress and hydrologic fluctuation. Our analyses indicated low densities of these fishes in central or northern Everglades wet-prairie communities, and, in the absence of experimental data, little evidence of biotic effects in this spatially extensive habitat. There is no guarantee that this condition will be maintained, especially under the cumulative effects of future invasions or environmental change.

Mercury exposure in a high fish eating Bolivian Amazonian population with intense small-scale gold-mining activities.

PubMed

Barbieri, Flavia Laura; Cournil, Amandine; Gardon, Jacques

2009-08-01

Methylmercury exposure in Amazonian communities through fish consumption has been widely documented in Brazil. There is still a lack of data in other Amazonian countries, which is why we conducted this study in the Bolivian Amazon basin. Simple random sampling was used from a small village located in the lower Beni River, where there is intense gold mining and high fish consumption. All participants were interviewed and hair samples were taken to measure total mercury concentrations. The hair mercury geometric mean in the general population was 3.02 microg/g (CI: 2.69-3.37; range: 0.42-15.65). Age and gender were not directly associated with mercury levels. Fish consumption showed a positive relation and so did occupation, especially small-scale gold mining. Hair mercury levels were lower than those found in Brazilian studies, but still higher than in non-exposed populations. It is necessary to assess mercury exposure in the Amazonian regions where data is still lacking, using a standardized indicator.

Effects of environmental covariates and density on the catchability of fish populations and interpretation of catch per unit effort trends

USGS Publications Warehouse

Korman, Josh; Yard, Mike

2017-01-01

Article for outlet: Fisheries Research. Abstract: Quantifying temporal and spatial trends in abundance or relative abundance is required to evaluate effects of harvest and changes in habitat for exploited and endangered fish populations. In many cases, the proportion of the population or stock that is captured (catchability or capture probability) is unknown but is often assumed to be constant over space and time. We used data from a large-scale mark-recapture study to evaluate the extent of spatial and temporal variation, and the effects of fish density, fish size, and environmental covariates, on the capture probability of rainbow trout (Oncorhynchus mykiss) in the Colorado River, AZ. Estimates of capture probability for boat electrofishing varied 5-fold across five reaches, 2.8-fold across the range of fish densities that were encountered, 2.1-fold over 19 trips, and 1.6-fold over five fish size classes. Shoreline angle and turbidity were the best covariates explaining variation in capture probability across reaches and trips. Patterns in capture probability were driven by changes in gear efficiency and spatial aggregation, but the latter was more important. Failure to account for effects of fish density on capture probability when translating a historical catch per unit effort time series into a time series of abundance, led to 2.5-fold underestimation of the maximum extent of variation in abundance over the period of record, and resulted in unreliable estimates of relative change in critical years. Catch per unit effort surveys have utility for monitoring long-term trends in relative abundance, but are too imprecise and potentially biased to evaluate population response to habitat changes or to modest changes in fishing effort.

Estimating fish populations by removal methods with minnow traps in southeast Alaska streams.

Treesearch

M.D. Bryant

2002-01-01

Passive capture methods, such as minnow traps, are commonly used to capture fish for mark-recapture population estimates; however, they have not been used for removal methods. Minnow traps set for 90-min periods during three or four sequential capture occasions during the summer of 1996 were used to capture coho salmon Oncorhynchus kisutch fry and...

Investigating the effect of chemical stress and resource limitation on fish populations: A case study with Fundulus heteroclitus

EPA Science Inventory

Modeling exposure and recovery of fish and wildlife populations after stressor mitigation serves as a basis for evaluating population status and remediation success. The Atlantic killifish (Fundulus heteroclitus) is an important and well-studied model organism for understanding t...

The dynamics of fish populations in the Palancar stream,a small tributary of the river Guadalquivir, Spain

NASA Astrophysics Data System (ADS)

Bravo, Ramón; Soriguer, Mila C.; Villar, Noelia; Hernando, José A.

2001-02-01

The relationship between flooding and changes in the size distribution of fish populations in the Palancar stream confirms observations in other rivers. On average, density decreased by 36.2 % and biomass increased by 14.5 %, passing from a period of severe drought to one of heavier than normal rains. Precipitation is the most important of the many factors affecting the populations of the Palancar stream; the most evident changes all occurred after the drought. During the drought period, the marked seasonal fluctuation in flow was the most important factor regulating the population dynamics. Fish density and biomass varied in proportion to the water volume. During the rainy period, the studied section of the river was found to be an important reproduction and nursery area, with juveniles and individuals of reproduction age dominating. The presence of Micropterus salmoides, an introduced piscivorous species, is another factor affecting the population dynamics in the Palancar stream. The observed absence of age 0+ individuals of the dominant populations is considered a direct effect of predation.

Population growth rates of reef sharks with and without fishing on the great barrier reef: robust estimation with multiple models.

PubMed

Hisano, Mizue; Connolly, Sean R; Robbins, William D

2011-01-01

Overfishing of sharks is a global concern, with increasing numbers of species threatened by overfishing. For many sharks, both catch rates and underwater visual surveys have been criticized as indices of abundance. In this context, estimation of population trends using individual demographic rates provides an important alternative means of assessing population status. However, such estimates involve uncertainties that must be appropriately characterized to credibly and effectively inform conservation efforts and management. Incorporating uncertainties into population assessment is especially important when key demographic rates are obtained via indirect methods, as is often the case for mortality rates of marine organisms subject to fishing. Here, focusing on two reef shark species on the Great Barrier Reef, Australia, we estimated natural and total mortality rates using several indirect methods, and determined the population growth rates resulting from each. We used bootstrapping to quantify the uncertainty associated with each estimate, and to evaluate the extent of agreement between estimates. Multiple models produced highly concordant natural and total mortality rates, and associated population growth rates, once the uncertainties associated with the individual estimates were taken into account. Consensus estimates of natural and total population growth across multiple models support the hypothesis that these species are declining rapidly due to fishing, in contrast to conclusions previously drawn from catch rate trends. Moreover, quantitative projections of abundance differences on fished versus unfished reefs, based on the population growth rate estimates, are comparable to those found in previous studies using underwater visual surveys. These findings appear to justify management actions to substantially reduce the fishing mortality of reef sharks. They also highlight the potential utility of rigorously characterizing uncertainty, and applying multiple

Population Growth Rates of Reef Sharks with and without Fishing on the Great Barrier Reef: Robust Estimation with Multiple Models

PubMed Central

Hisano, Mizue; Connolly, Sean R.; Robbins, William D.

2011-01-01

Overfishing of sharks is a global concern, with increasing numbers of species threatened by overfishing. For many sharks, both catch rates and underwater visual surveys have been criticized as indices of abundance. In this context, estimation of population trends using individual demographic rates provides an important alternative means of assessing population status. However, such estimates involve uncertainties that must be appropriately characterized to credibly and effectively inform conservation efforts and management. Incorporating uncertainties into population assessment is especially important when key demographic rates are obtained via indirect methods, as is often the case for mortality rates of marine organisms subject to fishing. Here, focusing on two reef shark species on the Great Barrier Reef, Australia, we estimated natural and total mortality rates using several indirect methods, and determined the population growth rates resulting from each. We used bootstrapping to quantify the uncertainty associated with each estimate, and to evaluate the extent of agreement between estimates. Multiple models produced highly concordant natural and total mortality rates, and associated population growth rates, once the uncertainties associated with the individual estimates were taken into account. Consensus estimates of natural and total population growth across multiple models support the hypothesis that these species are declining rapidly due to fishing, in contrast to conclusions previously drawn from catch rate trends. Moreover, quantitative projections of abundance differences on fished versus unfished reefs, based on the population growth rate estimates, are comparable to those found in previous studies using underwater visual surveys. These findings appear to justify management actions to substantially reduce the fishing mortality of reef sharks. They also highlight the potential utility of rigorously characterizing uncertainty, and applying multiple

Fish-allergic patients may be able to eat fish.

PubMed

Mourad, Ahmad A; Bahna, Sami L

2015-03-01

Reported fish allergy prevalence varies widely, with an estimated prevalence of 0.2% in the general population. Sensitization to fish can occur by ingestion, skin contact or inhalation. The manifestations can be IgE or non-IgE mediated. Several fish allergens have been identified, with parvalbumins being the major allergen in various species. Allergenicity varies among fish species and is affected by processing or preparation methods. Adverse reactions after eating fish are often claimed to be 'allergy' but could be a reaction to hidden food allergen, fish parasite, fish toxins or histamine in spoiled fish. Identifying such causes would allow free consumption of fish. Correct diagnosis of fish allergy, including the specific species, might provide the patient with safe alternatives. Patients have been generally advised for strict universal avoidance of fish. However, testing with various fish species or preparations might identify one or more forms that can be tolerated.

Mercury in fish from the Madeira River and health risk to Amazonian and riverine populations.

PubMed

Soares, José Maria; Gomes, José M; Anjos, Marcelo R; Silveira, Josianne N; Custódio, Flavia B; Gloria, M Beatriz A

2018-07-01

The objective of this study was to quantify total mercury in highly popular Amazonian fish pacu, curimatã, jaraqui, and sardinha from the Madeira River and to estimate the exposure to methylmercury from fish consumption. The samples were obtained from two locations - Puruzinho Igarapé and Santa Rosa - near Humaitá, Amazonia, Brazil in two seasons of 2015 (high and low waters). The fish were identified, weighed and measured, and lipids were quantified. Total mercury was determined by gold amalgamation-atomic absorption spectrometry. Mean levels were used to calculate exposure of Amazonian and riverine populations. There was significant correlation (p < 0.05) between length × weight for all fish; length × lipid and weight × lipid were significant only for pacu. Total mercury levels varied along muscle tissue for the fish, except for sardinha; therefore muscle from the dorsal area along the fish were sampled, homogenized and used for analysis. The levels of total mercury varied from 0.01 to 0.46 mg/kg, with higher median levels in sardinha (0.24 mg/kg), followed by curimatã (0.16 mg/kg), jaraqui (0.13 mg/kg) and pacu (0.04 mg/kg), corresponding with the respective feeding habits along the trophic chain. Total mercury levels were not affected by the location of fish capture and by high and low waters seasons. Total mercury correlated significantly with length and weight for jaraqui and with length for sardinha (negative correlation). Total mercury levels in fish complied with legislation; however, exposures to methylmercury from fish consumption overpassed the safe intake reference dose for sardinha for Amazonians; however, for the riverine communities, all of the fish would cause potential health risk, mainly for children and women of childbearing age. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fish mycobacteriosis (Tuberculosis)

USGS Publications Warehouse

Parisot, T.J.; Wood, J.W.

1959-01-01

The etiologic agent for the bacterial disease, "fish tuberculosis" (more correctly "mycobacteriosis"), was first observed in carp in 189& from a pond in France. Subsequently similar agents have been isolated from or observed in fish in fresh water, salt water, and brackish water, in fish in aquaria, hatcheries, and natural habitat~ (wild populations of fish). The disease has been recognized as an important infection among hatchery reared salmonid fishes on the West Coast of the United States, and in aquarium fishes such as the neon tetra, the Siamese fighting fish, and in salt water fish held in zoological displays.

The impact of United States recreational fisheries on marine fish populations.

PubMed

Coleman, Felicia C; Figueira, Will F; Ueland, Jeffrey S; Crowder, Larry B

2004-09-24

We evaluated the commercial and recreational fishery landings over the past 22 years, first at the national level, then for populations of concern (those that are overfished or experiencing overfishing), and finally by region. Recreational landings in 2002 account for 4% of total marine fish landed in the United States. With large industrial fisheries excluded (e.g., menhaden and pollock), the recreational component rises to 10%. Among populations of concern, recreational landings in 2002 account for 23% of the total nationwide, rising to 38% in the South Atlantic and 64% in the Gulf of Mexico. Moreover, it affects many of the most-valued overfished species-including red drum, bocaccio, and red snapper-all of which are taken primarily in the recreational fishery.

Estimating multi-factor cumulative watershed effects on fish populations with an individual-based model

Treesearch

Bret C. Harvey; Steven F. Railsback

2007-01-01

While the concept of cumulative effects is prominent in legislation governing environmental management, the ability to estimate cumulative effects remains limited. One reason for this limitation is that important natural resources such as fish populations may exhibit complex responses to changes in environmental conditions, particularly to alteration of multiple...

Relationship between snail population density and infection status of snails and fish with zoonotic trematodes in Vietnamese carp nurseries.

PubMed

Clausen, Jesper Hedegaard; Madsen, Henry; Murrell, K Darwin; Phan Thi, Van; Nguyen Manh, Hung; Viet, Khue Nguyen; Dalsgaard, Anders

2012-01-01

Fish-borne zoonotic trematodes (FZT) are a food safety and health concern in Vietnam. Humans and other final hosts acquire these parasites from eating raw or under-cooked fish with FZT metacercariae. Fish raised in ponds are exposed to cercariae shed by snail hosts that are common in fish farm ponds. Previous risk assessment on FZT transmission in the Red River Delta of Vietnam identified carp nursery ponds as major sites of transmission. In this study, we analyzed the association between snail population density and heterophyid trematode infection in snails with the rate of FZT transmission to juvenile fish raised in carp nurseries. Snail population density and prevalence of trematode (Heterophyidae) infections were determined in 48 carp nurseries producing Rohu juveniles, (Labeo rohita) in the Red River Delta area. Fish samples were examined at 3, 6 and 9 weeks after the juvenile fish were introduced into the ponds. There was a significant positive correlation between prevalence of FZT metacercariae in juvenile fish and density of infected snails. Thus, the odds of infection in juvenile fish were 4.36 and 11.32 times higher for ponds with medium and high density of snails, respectively, compared to ponds where no infected snails were found. Further, the intensity of fish FZT infections increased with the density of infected snails. Interestingly, however, some ponds with no or few infected snails were collected also had high prevalence and intensity of FZT in juvenile fish. This may be due to immigration of cercariae into the pond from external water sources. The total number and density of potential host snails and density of host snails infected with heterophyid trematodes in the aquaculture pond is a useful predictor for infections in juvenile fish, although infection levels in juvenile fish can occur despite low density or absence infected snails. This suggests that intervention programs to control FZT infection of fish should include not only intra

Fishing down the largest coral reef fish species.

PubMed

Fenner, Douglas

2014-07-15

Studies on remote, uninhabited, near-pristine reefs have revealed surprisingly large populations of large reef fish. Locations such as the northwestern Hawaiian Islands, northern Marianas Islands, Line Islands, U.S. remote Pacific Islands, Cocos-Keeling Atoll and Chagos archipelago have much higher reef fish biomass than islands and reefs near people. Much of the high biomass of most remote reef fish communities lies in the largest species, such as sharks, bumphead parrots, giant trevally, and humphead wrasse. Some, such as sharks and giant trevally, are apex predators, but others such as bumphead parrots and humphead wrasse, are not. At many locations, decreases in large reef fish species have been attributed to fishing. Fishing is well known to remove the largest fish first, and a quantitative measure of vulnerability to fishing indicates that large reef fish species are much more vulnerable to fishing than small fish. The removal of large reef fish by fishing parallels the extinction of terrestrial megafauna by early humans. However large reef fish have great value for various ecological roles and for reef tourism. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fish populations associated with habitat-modified piers and natural woody debris in Piedmont Carolina reservoirs

USGS Publications Warehouse

Barwick, R.D.; Kwak, T.J.; Noble, R.L.; Barwick, D.H.

2004-01-01

A primary concern associated with reservoir shoreline residential development is reduction of littoral habitat complexity and diversity. One potential approach to compensate for this is the deployment of artificial-habitat modules under existing piers, but the benefit of this practice has not been demonstrated. To evaluate the effect of pier habitat modifications on fish populations in two Piedmont Carolina reservoirs, we studied 77 piers located on forty-seven, 100-m transects that were modified using plastic "fish hab" modules augmented with brush (brushed habs), hab modules alone (habs), or left unaltered for reference purposes. We sampled fish from all piers and transects during April, July, and October 2001 using a boat-mounted electrofisher. With few exceptions, catch rates were higher at brushed-hab piers and piers with habs than at reference piers during all seasons. Similarly, during spring and summer, fish abundance was generally higher on transects containing natural woody debris, brushed habs, and habs than on reference-developed transects; however, during fall, there were exceptions. Therefore, fish abundance associated with shorelines in these reservoirs appears to be related to the structural complexity of available habitat rather than structure composition. One year after installation, 92% of pier owners responding to a mail survey expressed satisfaction with pier modifications. Supplementing piers with habitat structures is recommended to enhance littoral habitat complexity for fishes in residentially developed reservoirs.

Rapid estimation of microbial populations in fish samples by using terminal restriction fragment length polymorphism analysis of 16S rDNA.

PubMed

Tanaka, Yuichiro; Takahashi, Hajime; Kitazawa, Nao; Kimura, Bon

2010-01-01

A rapid system using terminal restriction fragment length polymorphism (T-RFLP) analysis targeting 16S rDNA is described for microbial population analysis in edible fish samples. The defined terminal restriction fragment database was constructed by collecting 102 strains of bacteria representing 53 genera that are associated with fish. Digestion of these 102 strains with two restriction enzymes, HhaI and MspI, formed 54 pattern groups with discrimination to the genus level. This T-RFLP system produced results comparable to those from a culture-based method in six natural fish samples with a qualitative correspondence of 71.4 to 92.3%. Using the T-RFLP system allowed an estimation of the microbial population within 7 h. Rapid assay of the microbial population is advantageous for food manufacturers and testing laboratories; moreover, the strategy presented here allows adaptation to specific testing applications.

Artificial barriers prevent genetic recovery of small isolated populations of a low-mobility freshwater fish.

PubMed

Coleman, R A; Gauffre, B; Pavlova, A; Beheregaray, L B; Kearns, J; Lyon, J; Sasaki, M; Leblois, R; Sgro, C; Sunnucks, P

2018-06-01

Habitat loss and fragmentation often result in small, isolated populations vulnerable to environmental disturbance and loss of genetic diversity. Low genetic diversity can increase extinction risk of small populations by elevating inbreeding and inbreeding depression, and reducing adaptive potential. Due to their linear nature and extensive use by humans, freshwater ecosystems are especially vulnerable to habitat loss and fragmentation. Although the effects of fragmentation on genetic structure have been extensively studied in migratory fishes, they are less understood in low-mobility species. We estimated impacts of instream barriers on genetic structure and diversity of the low-mobility river blackfish (Gadopsis marmoratus) within five streams separated by weirs or dams constructed 45-120 years ago. We found evidence of small-scale (<13 km) genetic structure within reaches unimpeded by barriers, as expected for a fish with low mobility. Genetic diversity was lower above barriers in small streams only, regardless of barrier age. In particular, one isolated population showed evidence of a recent bottleneck and inbreeding. Differentiation above and below the barrier (F ST  = 0.13) was greatest in this stream, but in other streams did not differ from background levels. Spatially explicit simulations suggest that short-term barrier effects would not be detected with our data set unless effective population sizes were very small (<100). Our study highlights that, in structured populations, the ability to detect short-term genetic effects from barriers is reduced and requires more genetic markers compared to panmictic populations. We also demonstrate the importance of accounting for natural population genetic structure in fragmentation studies.

POPULATION DECLINE IN STREAM FISH

EPA Science Inventory

Over half of the streams in the Mid-Atlantic Highlands have fish communities that are in fair or poor condition, and the EPA concluded that physical habitat alteration represents the greatest potential stressor across this region. A quantitative method for relating habitat quali...

Topographic and Genetic Markers of Landscape Change: Landslides and Isolated Fish Populations Demarcating Basin-wide Erosional Waves Above the Cascadia Subduction Zone

NASA Astrophysics Data System (ADS)

Lyons, N. J.; Wegmann, K. W.; Raley, M.

2013-12-01

A cascade of geomorphic and biotic responses to river incision can be modulated by glacial-interglacial cycles. Prior investigations have revealed the complex fluvial responses to climate and tectonic uplift above the Cascadia margin. Reduced sediment supply or increased stream discharge during interglacials is responsible for incision and preservation of terraces, whose basal strath unconformities were formed during glacial periods. A river incision record is provided by a flight of well-preserved stream terraces in the Clearwater River basin of the Olympic Mountains. Using numerical modeling and field observations, we will present analyses of stream topography and geometry, knickpoint location and age, and landslide frequency to assess hillslope and stream coupling in response to millennium-scale stream incision in the Clearwater River basin. We hypothesize that incision into a late Pleistocene terrace initiated a wave of erosion that is now expressed as increased landslide frequency on hillslopes, and as knickpoints on streams. Hillslopes are steepened to critical landslide thresholds as the erosional wave propagates through the basin. Aerial photographs and landslide inventories reveal that landslide scars cluster along the lower hillslopes below a network of stream knickpoints present in many Clearwater tributaries. Also within the premise of this hypothesis, aquatic organisms would become isolated above knickpoints once waterfalls reach an impassable height. Knickpoints then block upstream passage of fish, which instigates genetic drift and decreases population genetic variation. Introduction of alleles--alternative forms of a gene--to fish populations upstream of knickpoints is then limited to mutations, which along with the genetic mutation rate of a species, operates as a 'molecular clock' that records the time since knickpoint formation. We collected and analyzed DNA from Cutthroat trout (Oncorhynchus clarkii) specimens above knickpoints to assess the

Modeling unobserved sources of heterogeneity in animal abundance using a Dirichlet process prior

USGS Publications Warehouse

Dorazio, R.M.; Mukherjee, B.; Zhang, L.; Ghosh, M.; Jelks, H.L.; Jordan, F.

2008-01-01

In surveys of natural populations of animals, a sampling protocol is often spatially replicated to collect a representative sample of the population. In these surveys, differences in abundance of animals among sample locations may induce spatial heterogeneity in the counts associated with a particular sampling protocol. For some species, the sources of heterogeneity in abundance may be unknown or unmeasurable, leading one to specify the variation in abundance among sample locations stochastically. However, choosing a parametric model for the distribution of unmeasured heterogeneity is potentially subject to error and can have profound effects on predictions of abundance at unsampled locations. In this article, we develop an alternative approach wherein a Dirichlet process prior is assumed for the distribution of latent abundances. This approach allows for uncertainty in model specification and for natural clustering in the distribution of abundances in a data-adaptive way. We apply this approach in an analysis of counts based on removal samples of an endangered fish species, the Okaloosa darter. Results of our data analysis and simulation studies suggest that our implementation of the Dirichlet process prior has several attractive features not shared by conventional, fully parametric alternatives. ?? 2008, The International Biometric Society.

Epizootics of wild fish induced by farm fish.

PubMed

Krkosek, Martin; Lewis, Mark A; Morton, Alexandra; Frazer, L Neil; Volpe, John P

2006-10-17

The continuing decline of ocean fisheries and rise of global fish consumption has driven aquaculture growth by 10% annually over the last decade. The association of fish farms with disease emergence in sympatric wild fish stocks remains one of the most controversial and unresolved threats aquaculture poses to coastal ecosystems and fisheries. We report a comprehensive analysis of the spread and impact of farm-origin parasites on the survival of wild fish populations. We mathematically coupled extensive data sets of native parasitic sea lice (Lepeophtheirus salmonis) transmission and pathogenicity on migratory wild juvenile pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon. Farm-origin lice induced 9-95% mortality in several sympatric wild juvenile pink and chum salmon populations. The epizootics arise through a mechanism that is new to our understanding of emerging infectious diseases: fish farms undermine a functional role of host migration in protecting juvenile hosts from parasites associated with adult hosts. Although the migratory life cycles of Pacific salmon naturally separate adults from juveniles, fish farms provide L. salmonis novel access to juvenile hosts, in this case raising infection rates for at least the first approximately 2.5 months of the salmon's marine life (approximately 80 km of the migration route). Spatial segregation between juveniles and adults is common among temperate marine fishes, and as aquaculture continues its rapid growth, this disease mechanism may challenge the sustainability of coastal ecosystems and economies.

Omics and Environmental Science Genomic Approaches With Natural Fish Populations From Polluted Environments

PubMed Central

Bozinovic, Goran; Oleksiak, Marjorie F.

2010-01-01

Transcriptomics and population genomics are two complementary genomic approaches that can be used to gain insight into pollutant effects in natural populations. Transcriptomics identify altered gene expression pathways while population genomics approaches more directly target the causative genomic polymorphisms. Neither approach is restricted to a pre-determined set of genes or loci. Instead, both approaches allow a broad overview of genomic processes. Transcriptomics and population genomic approaches have been used to explore genomic responses in populations of fish from polluted environments and have identified sets of candidate genes and loci that appear biologically important in response to pollution. Often differences in gene expression or loci between polluted and reference populations are not conserved among polluted populations suggesting a biological complexity that we do not yet fully understand. As genomic approaches become less expensive with the advent of new sequencing and genotyping technologies, they will be more widely used in complimentary studies. However, while these genomic approaches are immensely powerful for identifying candidate gene and loci, the challenge of determining biological mechanisms that link genotypes and phenotypes remains. PMID:21072843

Overestimating Fish Counts by Non-Instantaneous Visual Censuses: Consequences for Population and Community Descriptions

PubMed Central

Ward-Paige, Christine; Mills Flemming, Joanna; Lotze, Heike K.

2010-01-01

Background Increasingly, underwater visual censuses (UVC) are used to assess fish populations. Several studies have demonstrated the effectiveness of protected areas for increasing fish abundance or provided insight into the natural abundance and structure of reef fish communities in remote areas. Recently, high apex predator densities (>100,000 individuals·km−2) and biomasses (>4 tonnes·ha−1) have been reported for some remote islands suggesting the occurrence of inverted trophic biomass pyramids. However, few studies have critically evaluated the methods used for sampling conspicuous and highly mobile fish such as sharks. Ideally, UVC are done instantaneously, however, researchers often count animals that enter the survey area after the survey has started, thus performing non-instantaneous UVC. Methodology/Principal Findings We developed a simulation model to evaluate counts obtained by divers deploying non-instantaneous belt-transect and stationary-point-count techniques. We assessed how fish speed and survey procedure (visibility, diver speed, survey time and dimensions) affect observed fish counts. Results indicate that the bias caused by fish speed alone is huge, while survey procedures had varying effects. Because the fastest fishes tend to be the largest, the bias would have significant implications on their biomass contribution. Therefore, caution is needed when describing abundance, biomass, and community structure based on non-instantaneous UVC, especially for highly mobile species such as sharks. Conclusions/Significance Based on our results, we urge that published literature state explicitly whether instantaneous counts were made and that survey procedures be accounted for when non-instantaneous counts are used. Using published density and biomass values of communities that include sharks we explore the effect of this bias and suggest that further investigation may be needed to determine pristine shark abundances and the existence of inverted

Fish immune responses to parasitic copepod (namely sea lice) infection.

PubMed

Fast, Mark D

2014-04-01

Parasitic copepods, in particular sea lice, have considerable impacts upon global freshwater and marine fisheries, with major economic consequences recognized primarily in aquaculture. Sea lice have been a contentious issue with regards to interactions between farmed and wild populations of fish, in particular salmonids, and their potential for detrimental effects at a population level. The following discussion will pertain to aquatic parasitic copepod species for which we have significant information on the host-parasite interaction and host response to infection (Orders Cyclopoida, Poecilostomatoida and Siphonostomatoida). This review evaluates prior research in terms of contributions to understanding parasite stage specific responses by the host, and in many cases draws upon model organisms like Lepeophtheirus salmonis and Atlantic salmon to convey important concepts in fish responses to parasitic copepod infection. The article discusses TH1 and TH2-like host responses in light of parasite immunomodulation of the host, current methods of immunological stimulation and where the current and future work in this field is heading. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fish collagen is an important panallergen in the Japanese population.

PubMed

Kobayashi, Y; Akiyama, H; Huge, J; Kubota, H; Chikazawa, S; Satoh, T; Miyake, T; Uhara, H; Okuyama, R; Nakagawara, R; Aihara, M; Hamada-Sato, N

2016-05-01

Collagen was identified as a fish allergen in early 2000s. Although its allergenic potential has been suggested to be low, risks associated with collagen as a fish allergen have not been evaluated to a greater extent. In this study, we aimed to clarify the importance of collagen as a fish allergen. Our results showed that 50% of Japanese patients with fish allergy had immunoglobulin E (IgE) against mackerel collagen, whereas 44% had IgE against mackerel parvalbumin. IgE inhibition assay revealed high cross-reactivity of mackerel collagen to 22 fish species (inhibition rates: 87-98%). Furthermore, a recently developed allergy test demonstrated that collagen triggered IgE cross-linking on mast cells. These data indicate that fish collagen is an important and very common panallergen in fish consumed in Japan. The high rate of individuals' collagen allergy may be attributable to the traditional Japanese custom of raw fish consumption. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fish consumption and risk of subclinical brain abnormalities on MRI in older adults.

PubMed

Virtanen, J K; Siscovick, D S; Longstreth, W T; Kuller, L H; Mozaffarian, D

2008-08-05

To investigate the association between fish consumption and subclinical brain abnormalities. In the population-based Cardiovascular Health Study, 3,660 participants age > or =65 underwent an MRI scan in 1992-1994. Five years later, 2,313 were scanned. Neuroradiologists assessed MRI scans in a standardized and blinded manner. Food frequency questionnaires were used to assess dietary intakes. Participants with known cerebrovascular disease were excluded from the analyses. After adjustment for multiple risk factors, the risk of having one or more prevalent subclinical infarcts was lower among those consuming tuna/other fish > or =3 times/week, compared to <1/month (relative risk 0.74, 95% CI = 0.54-1.01, p = 0.06, p trend = 0.03). Tuna/other fish consumption was also associated with trends toward lower incidence of subclinical infarcts. Additionally, tuna/other fish intake was associated with better white matter grade, but not with sulcal and ventricular grades, markers of brain atrophy. No significant associations were found between fried fish consumption and any subclinical brain abnormalities. Among older adults, modest consumption of tuna/other fish, but not fried fish, was associated with lower prevalence of subclinical infarcts and white matter abnormalities on MRI examinations. Our results add to prior evidence that suggest that dietary intake of fish with higher eicosapentaenoic acid and docosahexaenoic acid content, and not fried fish intake, may have clinically important health benefits.

Mercury concentrations in China's coastal waters and implications for fish consumption by vulnerable populations.

PubMed

Tong, Yindong; Wang, Mengzhu; Bu, Xiaoge; Guo, Xin; Lin, Yan; Lin, Huiming; Li, Jing; Zhang, Wei; Wang, Xuejun

2017-12-01

We assessed mercury (Hg) pollution in China's coastal waters, including the Bohai Sea, the Yellow Sea, the East China Sea and the South China Sea, based on a nationwide dataset from 301 sampling sites. A methylmercury (MeHg) intake model for humans based on the marine food chain and human fish consumption was established to determine the linkage between water pollutants and the pollutant intake by humans. The predicted MeHg concentration in fish from the Bohai Sea was the highest among the four seas included in the study. The MeHg intake through dietary ingestion was dominant for the fish and was considerably higher than the MeHg intake through water respiration. The predicted MeHg concentrations in human blood in the coastal regions of China ranged from 1.37 to 2.77 μg/L for pregnant woman and from 0.43 to 1.00 μg/L for infants, respectively, based on different diet sources. The carnivorous fish consumption advisory for pregnant women was estimated to be 288-654 g per week to maintain MeHg concentrations in human blood at levels below the threshold level (4.4 μg/L established by the US Environmental Protection Agency). With a 50% increase in Hg concentrations in water in the Bohai Sea, the bioaccumulated MeHg concentration (4.5 μg/L) in the fish consumers will be higher than the threshold level. This study demonstrates the importance in controlling Hg pollution in China's coastal waters. An official recommendation guideline for the fish consumption rate and its sources will be necessary for vulnerable populations in China. Copyright © 2017 Elsevier Ltd. All rights reserved.

Scalable population estimates using spatial-stream-network (SSN) models, fish density surveys, and national geospatial database frameworks for streams

Treesearch

Daniel J. Isaak; Jay M. Ver Hoef; Erin E. Peterson; Dona L. Horan; David E. Nagel

2017-01-01

Population size estimates for stream fishes are important for conservation and management, but sampling costs limit the extent of most estimates to small portions of river networks that encompass 100s–10 000s of linear kilometres. However, the advent of large fish density data sets, spatial-stream-network (SSN) models that benefit from nonindependence among samples,...

Fish can get diseases too

USGS Publications Warehouse

Winton, J.R.; Mesa, M.; Kurath, G.; Elliot, D.

2005-01-01

Infectious diseases are increasingly recognized as an important component of the ecology of fish in the wild. Many of the viral, bacterial, protozoan and fungal pathogens of fish that were initially discovered in captive fish have their origin among wild populations; however, the impact of disease among these free-ranging stocks has been difficult to study. At the WFRC, combinations of field and laboratory investigations, aided by the tools of molecular biology, have begun to provide information on the ecology of infectious diseases among natural populations of fish in both freshwater and marine ecosystems.

A synthesis of ecological and fish-community changes in Lake Ontario, 1970-2000

USGS Publications Warehouse

Mills, E.L.; Casselman, J.M.; Dermott, R.; Fitzsimons, J.D.; Gal, G.; Holeck, K. T.; Hoyle, J.A.; Johannsson, O.E.; Lantry, B.F.; Makarewicz, J.C.; Millard, E.S.; Munawar, I.F.; Munawar, M.; O'Gorman, R.; Owens, R.W.; Rudstam, L. G.; Schaner, T.; Stewart, T.J.

2005-01-01

We assessed stressors associated with ecological and fishcommunity changes in Lake Ontario since 1970, when the first symposium on Salmonid Communities in Oligotrophic Lakes (SCOL I) was held (J. Fish. Res. Board Can. 29: 613-616). Phosphorus controls implemented in the early 1970s were undeniably successful; lower food-web studies showed declines in algal abundance and epilimnetic zooplankton production and a shift in pelagic primary productivity toward smaller organisms. Stressors on the fish community prior to 1970 such as exploitation, sea lamprey (Petromyzon marinus) predation, and effects of nuisance populations of alewife (Alosa pseudoharengus) were largely ameliorated by the 1990s. The alewife became a pivotal species supporting a multi-million-dollar salmonid sport fishery, but alewife-induced thiamine deficiency continued to hamper restoration and sustainability of native lake trout (Salvelinus namaycush). Expanding salmonine populations dependent on alewife raised concerns about predator demand and prey supply, leading to reductions in salmonine stocking in the early 1990s. Relaxation of the predation impact by alewives and their shift to deeper water allowed recovery of native fishes such as threespine stickleback (Gasterosteus aculeatus) and emerald shiner (Notropis atherinoides). The return of the Lake Ontario ecosystem to historical conditions has been impeded by unplanned introductions. Establishment of Dreissena spp. led to increased water clarity and increased vectoring of lower trophic-level production to benthic habitats and contributed to the collapse of Diporeia spp. populations, behavioral modifications of key fish species, and the decline of native lake whitefish (Coregonus clupeaformis). Despite reduced productivity, exotic-species introductions, and changes in the fish community, offshore Mysis relicta populations remained relatively stable. The effects of climate and climate change on the population abundance and dynamics of Lake Ontario

Mitochondrial DNA variation in natural populations of endangered Indian feather-back fish, Chitala chitala.

PubMed

Mandal, Anup; Mohindra, Vindhya; Singh, Rajeev Kumar; Punia, Peyush; Singh, Ajay Kumar; Lal, Kuldeep Kumar

2012-02-01

Genetic variation at mitochondrial cytochrome b (cyt b) and D-loop region reveals the evidence of population sub-structuring in Indian populations of highly endangered primitive feather-back fish Chitala chitala. Samples collected through commercial catches from eight riverine populations from different geographical locations of India were analyzed for cyt b region (307 bp) and D-loop region (636-716 bp). The sequences of the both the mitochondrial regions revealed high haplotype diversity and low nucleotide diversity. The patterns of genetic diversity, haplotypes networks clearly indicated two distinct mitochondrial lineages and mismatch distribution strongly suggest a historical influence on the genetic structure of C. chitala populations. The baseline information on genetic variation and the evidence of population sub-structuring generated from this study would be useful for planning effective strategies for conservation and rehabilitation of this highly endangered species.

Assessing impacts of land-applied manure from concentrated animal feeding operations on fish populations and communities.

PubMed

Leet, Jessica K; Lee, Linda S; Gall, Heather E; Goforth, Reuben R; Sassman, Stephen; Gordon, Denise A; Lazorchak, James M; Smith, Mark E; Jafvert, Chad T; Javfert, Chad T; Sepúlveda, Maria S

2012-12-18

Concentrated animal feeding operation (CAFO) manure is a cost-effective fertilizer. In the Midwest, networks of subsurface tile-drains expedite transport of animal hormones and nutrients from land-applied CAFO manure to adjacent waterways. The objective of this study was to evaluate impacts of land-applied CAFO manure on fish populations and communities. Water chemistry including hormone, pesticide, and nutrient concentrations was characterized from study sites along with fish assemblage structure, growth, and endocrine disruption assessed in selected fish species. Although most CAFO water samples had hormone concentrations <1 ng/L, equivalent concentrations for 17β-E2 and 17α-TB peaked at >30 ng/L each during the period of spawning, hatching, and development for resident fishes. CAFO sites had lower fish species richness, and fishes exhibited faster somatic growth and lower reproductive condition compared to individuals from the reference site. Fathead minnows (Pimephales promelas) exposed to CAFO ditchwater during early developmental stages exhibited significantly skewed sex ratios toward males. Maximum observed hormone concentrations were well above the lowest observable effect concentrations for these hormones; however, complexities at the field scale make it difficult to directly relate hormone concentration and impacts on fish. Complicating factors include the consistent presence of pesticides and nutrients, and the difference in temperature and stream architecture of the CAFO-impacted ditches compared to the reference site (e.g., channelization, bottom substrate, shallow pools, and riparian cover).

On the maintenance of genetic variation and adaptation to environmental change: considerations from population genomics in fishes.

PubMed

Bernatchez, L

2016-12-01

The first goal of this paper was to overview modern approaches to local adaptation, with a focus on the use of population genomics data to detect signals of natural selection in fishes. Several mechanisms are discussed that may enhance the maintenance of genetic variation and evolutionary potential, which have been overlooked and should be considered in future theoretical development and predictive models: the prevalence of soft sweeps, polygenic basis of adaptation, balancing selection and transient polymorphisms, parallel evolution, as well as epigenetic variation. Research on fish population genomics has provided ample evidence for local adaptation at the genome level. Pervasive adaptive evolution, however, seems to almost never involve the fixation of beneficial alleles. Instead, adaptation apparently proceeds most commonly by soft sweeps entailing shifts in frequencies of alleles being shared between differentially adapted populations. One obvious factor contributing to the maintenance of standing genetic variation in the face of selective pressures is that adaptive phenotypic traits are most often highly polygenic, and consequently the response to selection should derive mostly from allelic co-variances among causative loci rather than pronounced allele frequency changes. Balancing selection in its various forms may also play an important role in maintaining adaptive genetic variation and the evolutionary potential of species to cope with environmental change. A large body of literature on fishes also shows that repeated evolution of adaptive phenotypes is a ubiquitous evolutionary phenomenon that seems to occur most often via different genetic solutions, further adding to the potential options of species to cope with a changing environment. Moreover, a paradox is emerging from recent fish studies whereby populations of highly reduced effective population sizes and impoverished genetic diversity can apparently retain their adaptive potential in some

A Mixed-Method Approach for Quantifying Illegal Fishing and Its Impact on an Endangered Fish Species.

PubMed

Free, Christopher M; Jensen, Olaf P; Mendsaikhan, Bud

2015-01-01

Illegal harvest is recognized as a widespread problem in natural resource management. The use of multiple methods for quantifying illegal harvest has been widely recommended yet infrequently applied. We used a mixed-method approach to evaluate the extent, character, and motivations of illegal gillnet fishing in Lake Hovsgol National Park, Mongolia and its impact on the lake's fish populations, especially that of the endangered endemic Hovsgol grayling (Thymallus nigrescens). Surveys for derelict fishing gear indicate that gillnet fishing is widespread and increasing and that fishers generally use 3-4 cm mesh gillnet. Interviews with resident herders and park rangers suggest that many residents fish for subsistence during the spring grayling spawning migration and that some residents fish commercially year-round. Interviewed herders and rangers generally agree that fish population sizes are decreasing but are divided on the causes and solutions. Biological monitoring indicates that the gillnet mesh sizes used by fishers efficiently target Hovsgol grayling. Of the five species sampled in the monitoring program, only burbot (Lota lota) showed a significant decrease in population abundance from 2009-2013. However, grayling, burbot, and roach (Rutilus rutilus) all showed significant declines in average body size, suggesting a negative fishing impact. Data-poor stock assessment methods suggest that the fishing effort equivalent to each resident family fishing 50-m of gillnet 11-15 nights per year would be sufficient to overexploit the grayling population. Results from the derelict fishing gear survey and interviews suggest that this level of effort is not implausible. Overall, we demonstrate the ability for a mixed-method approach to effectively describe an illegal fishery and suggest that these methods be used to assess illegal fishing and its impacts in other protected areas.

A Mixed-Method Approach for Quantifying Illegal Fishing and Its Impact on an Endangered Fish Species

PubMed Central

Free, Christopher M.; Jensen, Olaf P.; Mendsaikhan, Bud

2015-01-01

Illegal harvest is recognized as a widespread problem in natural resource management. The use of multiple methods for quantifying illegal harvest has been widely recommended yet infrequently applied. We used a mixed-method approach to evaluate the extent, character, and motivations of illegal gillnet fishing in Lake Hovsgol National Park, Mongolia and its impact on the lake’s fish populations, especially that of the endangered endemic Hovsgol grayling (Thymallus nigrescens). Surveys for derelict fishing gear indicate that gillnet fishing is widespread and increasing and that fishers generally use 3–4 cm mesh gillnet. Interviews with resident herders and park rangers suggest that many residents fish for subsistence during the spring grayling spawning migration and that some residents fish commercially year-round. Interviewed herders and rangers generally agree that fish population sizes are decreasing but are divided on the causes and solutions. Biological monitoring indicates that the gillnet mesh sizes used by fishers efficiently target Hovsgol grayling. Of the five species sampled in the monitoring program, only burbot (Lota lota) showed a significant decrease in population abundance from 2009–2013. However, grayling, burbot, and roach (Rutilus rutilus) all showed significant declines in average body size, suggesting a negative fishing impact. Data-poor stock assessment methods suggest that the fishing effort equivalent to each resident family fishing 50-m of gillnet 11–15 nights per year would be sufficient to overexploit the grayling population. Results from the derelict fishing gear survey and interviews suggest that this level of effort is not implausible. Overall, we demonstrate the ability for a mixed-method approach to effectively describe an illegal fishery and suggest that these methods be used to assess illegal fishing and its impacts in other protected areas. PMID:26625154

Gender differences in attitudes about fish safety in a coastal population.

PubMed

Burger, J

1998-02-06

Behavioral approaches to reducing the adverse health effects of consuming fish with high contaminant levels benefit from understanding attitudes and perceptions about the relative safety of fish. Gender differences in attitudes about fish safety were investigated by interviewing 197 men and 94 women who attended a Duck Decoy show at Tuckerton, NJ. There were significant gender differences in perceptions of the safety of fish, ducks, and deer, with women generally believing that it was less safe to eat these foods than did men. Although people correctly perceived that ocean fish were safer than bay-caught fish from a chemical contaminant perspective, perceptions were less clear with respect to consuming predatory or herbivorous, or large versus small fish. Although men significantly perceived small fish as safer than large fish, women did not. However, people correctly believed that bluefish (a predaceous fish) were less safe than flounder (an herbivore). People uniformly believed it was safer to eat fish they caught themselves or bought in a fish store than those from a supermarket. These results suggest that any program to inform the public about the potential dangers from contaminated fish should take into account gender differences in perceptions.

Population genetic structure of the acanthocephalan Acanthosentis cheni in anadromous, freshwater, and landlocked stocks of its fish host, Coilia nasus.

PubMed

Song, Rui; Li, Wen X; Wu, Shan G; Zou, Hong; Wang, Gui T

2014-04-01

The acanthocephalan Acanthosentis cheni was found in anadromous, freshwater, and landlocked stocks of its fish host, Coilia nasus. To examine the genetic variations of the acanthocephalan among the 3 populations with the adaptation of the host to the freshwater, the genetic structure of the helminth was investigated in anadromous (Zhoushan and Chongming islands, and Anqing), freshwater (Anqing, Ezhou, and Poyang Lake), and landlocked (Tian'ezhou Reserve) populations by sequencing intergenic transcribed spacers (ITS) of the ribosomal RNA coding genes. Low Fst values and high gene flow were found among the 7 populations (Fst = 0.0135, P = 0.2723; Nm = 36.48) and the 3 ecotypes of Acanthosentis cheni (Fst = 0.0178, P = 0.1044; Nm = 27.67). On the other hand, significant genetic differentiation of the C. nasus host populations was detected between the upstream and downstream areas of Xiaogu Mountain (Fst = 0.1961, P = 0.0030; Nm = 2.05), which is the farthest location of spawning migration for C. nasus . However, the migration break of the fish host appeared not to cause significant genetic differentiation of A. cheni populations between the upper and lower reaches of Xiaogu Mountain. Other factors might promote genetic exchange of A. cheni populations such as dispersal of the intermediate host by flooding or other fish species serving as the definitive or paratenic hosts. In Anqing, nucleotide diversity of the acanthocephalan was highest in the freshwater population (0.0038) and lower in the anadromous population (0.0026). This suggested that new mutations may have occurred in the freshwater A. cheni population in Anqing when adapting to a freshwater environment.

Fish consumption, fish oil supplements and risk of atherosclerosis in the Tromsø study.

PubMed

Johnsen, Stein Harald; Jacobsen, Bjarne K; Brækkan, Sigrid K; Hansen, John-Bjarne; Mathiesen, Ellisiv B

2018-05-25

Whether long-chain n-3 PUFAs of marine origin have an anti-atherogenic effect in the general population has hardly been studied. In this population-based study, we hypothesized that fatty fish and fish oil intake protect against development of novel atherosclerotic plaques and is associated with reduced plaque size. We obtained questionnaire-based information on fish consumption and carotid ultrasonography from 3900 persons aged 45-74 years. The questionnaires were validated by measuring serum concentrations of PUFAs and triglycerides in a subgroup. At follow-up seven years later, 2983 (76%) went through a second ultrasound scanning. Logistic regression and general linear models were used to analyze the outcome (plaque presence and plaque area) as a function of fish consumption, including analyses stratified on fish oil supplements. At baseline, lean fish intake < 1 time/week vs. 1-1.9 times/week was associated with risk of plaque (OR 1.34, 95% CI 1.03-1.76). Fatty fish intake and use of fish oil supplements were not statistically significantly associated with atherosclerosis at baseline. In persons without plaque at baseline, total fish consumption ≥3 times/week vs. 1-1.9 times/week was associated with risk of novel plaque (OR 1.32, 95% CI 1.01-1.73) and larger plaque area (1.76 mm 2 vs. 1.46 mm 2 , p = 0.02) at follow-up. Adjustments for use of fish oil supplements had no impact on the associations, and no interactions were seen between total, fatty or lean fish consumption and fish oil intake. We found no protective effect of fatty fish eating or fish oil supplements on atherosclerotic plaque formation or plaque area in a general population. Lean fish consumption was associated with a reduced risk for plaque in cross-sectional analysis, suggesting that the beneficial effects of fish consumption on atherosclerosis may be mediated through other mechanisms than n-3 PUFAs.

A Methodology for Analyzing the Aptitude Content of the Non-Prior Service Youth and Enlisted Apprentice Populations

DTIC Science & Technology

1985-05-29

POPULATIONS By William P. Hutzler Patricia A. Insley Betty Lou Bantor 29 May 1985 DISTRIBUTION LIMITED TO POD COMPONENTS ONLYr CTj SffM &f...10 SOURCE OF FUNDING NOS PROGRAM ELEMENT NO. PROJECT NO. TASK NO, WORK UNIT NO 12. PERSONAL AUTMOR(S) Hutzler. William P.; Inslev. Patricia...CONTENT OF THE NON-PRIOR SERVICE YOUTH AND ENLISTED APPRENTICE POPULATIONS By William P. Hutzler Patricia A. Insley Betty Lou Bantor 29 May 1985

Estimating the Marginal Causal Effect of Fish Consumption during Adolescence on Multiple Sclerosis: A Population-Based Incident Case-Control Study.

PubMed

Abdollahpour, Ibrahim; Nedjat, Saharnaz; Mansournia, Mohammad Ali; Sahraian, Mohammad Ali; Kaufman, Jay S

2018-01-01

Adolescence is considered as a critical time period in multiple sclerosis (MS) etiology. Nonetheless, there are insufficient reports regarding the potential role of fresh and canned fish consumptions during adolescence in MS etiology. The authors investigated the association between fresh and canned fish consumptions and MS. This was a population-based incident case-control study conducted in Tehran. Cases (n = 547) identified from Iranian Multiple Sclerosis Society between August 7, 2013, and November 17, 2015 were included in the study. Population-based controls (n = 1,057) were recruited by random digit telephone dialing without any matching. Inverse-probability-of-treatment weighing (IPTW) using 2 sets of propensity scores and model-based standardization were used to separately estimate the marginal odds ratio between fresh and canned fish consumptions in adolescence and MS. The marginal OR for fresh fish was 0.72 (95% CI 0.58-0.90; p = 0.005) in both IPTW analyses. Similarly, the marginal OR for canned fish consumption was 0.75 (95% CI 0.60-0.95; p = 0.014).The model-based standardized OR was 0.72 (95% CI 0.58-0.91; p = 0.008) for fresh and 0.73 (95% CI 0.59-0.94; p = 0.006) for canned fish consumption in adolescence. Subject to limitation of case-control studies in interpreting associations causally, this study suggests that both fresh and canned fish consumptions in adolescence can decrease the risk of MS. © 2018 S. Karger AG, Basel.

Mercury concentrations in lean fish from the Western Mediterranean Sea: Dietary exposure and risk assessment in the population of the Balearic Islands.

PubMed

Llull, Rosa Maria; Garí, Mercè; Canals, Miquel; Rey-Maquieira, Teresa; Grimalt, Joan O

2017-10-01

The present study reports total mercury (THg) and methylmercury (MeHg) concentrations in 32 different lean fish species from the Western Mediterranean Sea, with a special focus on the Balearic Islands. The concentrations of THg ranged between 0.05mg/kg ww and 3.1mg/kg ww (mean 0.41mg/kg ww). A considerable number of the most frequently fish species consumed by the Spanish population exceed the maximum levels proposed by the European legislation when they originate from the Mediterranean Sea, such as dusky grouper (100% of the examined specimens), common dentex (65%), conger (45%), common sole (38%), hake (26%) and angler (15%), among others. The estimated weekly intakes (EWI) in children (7-12 years of age) and adults from the Spanish population (2.7µg/kg bw and 2.1µg/kg bw, respectively) for population only consuming Mediterranean fish were below the provisional tolerable weekly intake (PTWI) of THg established by EFSA in 2012, 4µg/kg bw. However, the equivalent estimations for methylmercury, involving PTWI of 1.3µg/kg bw, were two times higher in children and above 50% in adults. For hake, sole, angler and dusky grouper, the most frequently consumed fish, the estimated weekly intakes in both children and adults were below the maximum levels accepted. These intakes correspond to maximum potential estimations because fish from non-Mediterranean origin is often consumed by the Spanish population including the one from the Balearic Islands. Copyright © 2017 Elsevier Inc. All rights reserved.

Enzymes in Fermented Fish.

PubMed

Giyatmi; Irianto, H E

Fermented fish products are very popular particularly in Southeast Asian countries. These products have unique characteristics, especially in terms of aroma, flavor, and texture developing during fermentation process. Proteolytic enzymes have a main role in hydrolyzing protein into simpler compounds. Fermentation process of fish relies both on naturally occurring enzymes (in the muscle or the intestinal tract) as well as bacteria. Fermented fish products processed using the whole fish show a different characteristic compared to those prepared from headed and gutted fish. Endogenous enzymes like trypsin, chymotrypsin, elastase, and aminopeptidase are the most involved in the fermentation process. Muscle tissue enzymes like cathepsins, peptidases, transaminases, amidases, amino acid decarboxylases, glutamic dehydrogenases, and related enzymes may also play a role in fish fermentation. Due to the decreased bacterial number during fermentation, contribution of microbial enzymes to proteolysis may be expected prior to salting of fish. Commercial enzymes are supplemented during processing for specific purposes, such as quality improvement and process acceleration. In the case of fish sauce, efforts to accelerate fermentation process and to improve product quality have been studied by addition of enzymes such as papain, bromelain, trypsin, pepsin, and chymotrypsin. © 2017 Elsevier Inc. All rights reserved.

One Fish, Two Fish, Redfish, You Fish!

ERIC Educational Resources Information Center

White, Katherine; Timmons, Maryellen; Medders, Paul

2011-01-01

The recreational fishing activity presented in this article provides a hands-on, problem-based experience for students; it unites biology, math, economics, environmental policy, and population dynamics concepts. In addition, the activity allows students to shape environmental policy in a realistic setting and evaluate their peers' work. By…

Contrasting Genetic Structure among Populations of Two Amphidromous Fish Species (Sicydiinae) in the Central West Pacific

PubMed Central

Taillebois, Laura; Castelin, Magalie; Ovenden, Jennifer R.; Bonillo, Céline; Keith, Philippe

2013-01-01

Both present-day and past processes can shape connectivity of populations. Pleistocene vicariant events and dispersal have shaped the present distribution and connectivity patterns of aquatic species in the Indo-Pacific region. In particular, the processes that have shaped distribution of amphidromous goby species still remain unknown. Previous studies show that phylogeographic breaks are observed between populations in the Indian and Pacific Oceans where the shallow Sunda shelf constituted a geographical barrier to dispersal, or that the large spans of open ocean that isolate the Hawaiian or Polynesian Islands are also barriers for amphidromous species even though they have great dispersal capacity. Here we assess past and present genetic structure of populations of two amphidromous fish (gobies of the Sicydiinae) that are widely distributed in the Central West Pacific and which have similar pelagic larval durations. We analysed sections of mitochondrial COI, Cytb and nuclear Rhodospine genes in individuals sampled from different locations across their entire known range. Similar to other Sicydiinae fish, intraspecific mtDNA genetic diversity was high for all species (haplotype diversity between 0.9–0.96). Spatial analyses of genetic variation in Sicyopus zosterophorum demonstrated strong isolation across the Torres Strait, which was a geologically intermittent land barrier linking Australia to Papua New Guinea. There was a clear genetic break between the northwestern and the southwestern clusters in Si. zosterophorum (φST = 0.67502 for COI) and coalescent analyses revealed that the two populations split at 306 Kyr BP (95% HPD 79–625 Kyr BP), which is consistent with a Pleistocene separation caused by the Torres Strait barrier. However, this geographical barrier did not seem to affect Sm. fehlmanni. Historical and demographic hypotheses are raised to explain the different patterns of population structure and distribution between these species. Strategies

Differences in the Metabolic Rates of Exploited and Unexploited Fish Populations: A Signature of Recreational Fisheries Induced Evolution?

PubMed Central

Hessenauer, Jan-Michael; Vokoun, Jason C.; Suski, Cory D.; Davis, Justin; Jacobs, Robert; O’Donnell, Eileen

2015-01-01

Non-random mortality associated with commercial and recreational fisheries have the potential to cause evolutionary changes in fish populations. Inland recreational fisheries offer unique opportunities for the study of fisheries induced evolution due to the ability to replicate study systems, limited gene flow among populations, and the existence of unexploited reference populations. Experimental research has demonstrated that angling vulnerability is heritable in Largemouth Bass Micropterus salmoides, and is correlated with elevated resting metabolic rates (RMR) and higher fitness. However, whether such differences are present in wild populations is unclear. This study sought to quantify differences in RMR among replicated exploited and unexploited populations of Largemouth Bass. We collected age-0 Largemouth Bass from two Connecticut drinking water reservoirs unexploited by anglers for almost a century, and two exploited lakes, then transported and reared them in the same pond. Field RMR of individuals from each population was quantified using intermittent-flow respirometry. Individuals from unexploited reservoirs had a significantly higher mean RMR (6%) than individuals from exploited populations. These findings are consistent with expectations derived from artificial selection by angling on Largemouth Bass, suggesting that recreational angling may act as an evolutionary force influencing the metabolic rates of fishes in the wild. Reduced RMR as a result of fisheries induced evolution may have ecosystem level effects on energy demand, and be common in exploited recreational populations globally. PMID:26039091

Modeling responses of large-river fish populations to global climate change through downscaling and incorporation of predictive uncertainty

USGS Publications Warehouse

Wildhaber, Mark L.; Wikle, Christopher K.; Anderson, Christopher J.; Franz, Kristie J.; Moran, Edward H.; Dey, Rima; Mader, Helmut; Kraml, Julia

2012-01-01

Climate change operates over a broad range of spatial and temporal scales. Understanding its effects on ecosystems requires multi-scale models. For understanding effects on fish populations of riverine ecosystems, climate predicted by coarse-resolution Global Climate Models must be downscaled to Regional Climate Models to watersheds to river hydrology to population response. An additional challenge is quantifying sources of uncertainty given the highly nonlinear nature of interactions between climate variables and community level processes. We present a modeling approach for understanding and accomodating uncertainty by applying multi-scale climate models and a hierarchical Bayesian modeling framework to Midwest fish population dynamics and by linking models for system components together by formal rules of probability. The proposed hierarchical modeling approach will account for sources of uncertainty in forecasts of community or population response. The goal is to evaluate the potential distributional changes in an ecological system, given distributional changes implied by a series of linked climate and system models under various emissions/use scenarios. This understanding will aid evaluation of management options for coping with global climate change. In our initial analyses, we found that predicted pallid sturgeon population responses were dependent on the climate scenario considered.

Habitat and fish population in the deep-sea Oculina coral ecosystem of the western Atlantic

USGS Publications Warehouse

2005-01-01

In this paper, we describe results from mapping studies conducted in 2001 and improvements to reef fish populations that have occurred in the last few years. We find that less than 10% of the area contains intact Oculina coral thickets, which we continue to attribute primarily to trawling. In addition, we find increased grouper density and male abundance inside the protected area, suggesting population recovery, and the appearance of juvenile speckled hind Epinephelus drummondhayi (family Serranidae), suggesting nursery function for this and possibly other commercially important species.

Mercury concentrations in Maine sport fishes

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

Stafford, C.P.; Haines, T.A.

1997-01-01

To assess mercury contamination of fish in Maine, fish were collected from 120 randomly selected lakes. The collection goal for each lake was five fish of the single most common sport fish species within the size range commonly harvested by anglers. Skinless, boneless fillets of fish from each lake were composited, homogenized, and analyzed for total mercury. The two most abundant species, brook trout Salvelinus fontinalis and smallmouth bass Micropterus dolomieu, were also analyzed individually. The composite fish analyses indicate high concentrations of mercury, particularly in large and long-lived nonsalmonid species. Chain pickerel Esox niger, smallmouth bass, largemouth bass Micropterusmore » salmoides, and white perch Morone americana had the highest average mercury concentrations, and brook trout and yellow perch Perca flavescens had the lowest. The mean species composite mercury concentration was positively correlated with a factor incorporating the average size and age of the fish. Lakes containing fish with high mercury concentrations were not clustered near known industrial or population centers but were commonest in the area within 150 km of the seacoast, reflecting the geographical distribution of species that contained higher mercury concentrations. Stocked and wild brook trout were not different in length or weight, but wild fish were older and had higher mercury concentrations. Fish populations maintained by frequent introductions of hatchery-produced fish and subject to high angler exploitation rates may consist of younger fish with lower exposure to environmental mercury and thus contain lower concentrations than wild populations.« less

Guidelines for use of fishes in research

USGS Publications Warehouse

Use of Fishes in Research Committee (joint committee of the American Fisheries Society, the American Institute of Fishery Research Biologists

2014-01-01

The 2004 and 2014 Guidelines were developed to provide a structure that advances appropriate attention toward valid experimental designs and procedures with aquatic animals while ensuring humane treatment of the experimental subjects. At a practical level, the Guidelines are intended to provide general recommendations on field and laboratory endeavors, such as sampling, holding, and handling fishes; to offer information on administrative matters, including regulations and permits; and to address typical ethical concerns, such as perceptions of pain or discomfort experienced by experimental subjects. These Guidelines must be recognized as guidelines. They are not intended to provide detailed instructions but rather to alert investigators to a broad array of topics and concerns to consider prior to initiating study. At a comprehensive level, the principles upon which these Guidelines are based are broadly applicable, and many of the described practices and approaches can be adapted to situations involving other aquatic animal species and conditions. Understanding the differences between fishes and other vertebrates, especially mammals, is critically important to conducting scientifically sound research with fishes. Disparities in life histories and mortality rates in fishes versus other vertebrates are critical in designing sustainable sampling levels in fish populations. The UFR Committee points out that (1) compared to mammalian populations, adult populations of many fish species persist despite very high natural mortality rates in juvenile stages by virtue of the fact that most species lay thousands or tens of thousands of eggs; (2) because of these mortality patterns, research on fishes, especially field research or research on early life stages, can involve, and often requires, much larger numbers of research subjects than does research on mammals; and (3) the animal handling and husbandry requirements for fishes are fundamentally different from those for

STORED RETINOIDS IN POPULATIONS OF AN ESTUARINE FISH, FUNDULUS HETERCLITUS, INDIGENOUS TO PCB-CONTAMINATED AND REFERENCE SITES

EPA Science Inventory

Concentrations of retinoids, derivatives of vitamin A, were measured in populations of the nonmigratory estuarine fish Fundulus heteroclitus, indigenous to a reference site and a site highly contaminated with polychlorinated biphenyls (PCBs) to address the hypothesis that contami...

Fish Rhabdoviruses

USGS Publications Warehouse

Kurath, G.; Winton, J.

2008-01-01

Many important viral pathogens of fish are members of the family Rhabdoviridae. The viruses in this large group cause significant losses in populations of wild fish as well as among fish reared in aquaculture. Fish rhabdoviruses often have a wide host and geographic range, and infect aquatic animals in both freshwater and seawater. The fish rhabdoviruses comprise a diverse collection of isolates that can be placed in one of two quite different groups: isolates that are members of the established genusNovirhabdovirus, and those that are most similar to members of the genus Vesiculovirus. Because the diseases caused by fish rhabdoviruses are important to aquaculture, diagnostic methods for their detection and identification are well established. In addition to regulations designed to reduce the spread of fish viruses, a significant body of research has addressed methods for the control or prevention of diseases caused by fish rhabdoviruses, including vaccination. The number of reported fish rhabdoviruses continues to grow as a result of the expansion of aquaculture, the increase in global trade, the development of improved diagnostic methods, and heightened surveillance activities. Fish rhabdoviruses serve as useful components of model systems to study vertebrate virus disease, epidemiology, and immunology.

Fish Assemblage Response to a Small Dam Removal in the Eightmile River System, Connecticut, USA

NASA Astrophysics Data System (ADS)

Poulos, Helen M.; Miller, Kate E.; Kraczkowski, Michelle L.; Welchel, Adam W.; Heineman, Ross; Chernoff, Barry

2014-11-01

We examined the effects of the Zemko Dam removal on the Eightmile River system in Salem, Connecticut, USA. The objective of this research was to quantify spatiotemporal variation in fish community composition in response to small dam removal. We sampled fish abundance over a 6-year period (2005-2010) to quantify changes in fish assemblages prior to dam removal, during drawdown, and for three years following dam removal. Fish population dynamics were examined above the dam, below the dam, and at two reference sites by indicator species analysis, mixed models, non-metric multidimensional scaling, and analysis of similarity. We observed significant shifts in fish relative abundance over time in response to dam removal. Changes in fish species composition were variable, and they occurred within 1 year of drawdown. A complete shift from lentic to lotic fishes failed to occur within 3 years after the dam was removed. However, we did observe increases in fluvial and transition (i.e., pool head, pool tail, or run) specialist fishes both upstream and downstream from the former dam site. Our results demonstrate the importance of dam removal for restoring river connectivity for fish movement. While the long-term effects of dam removal remain uncertain, we conclude that dam removals can have positive benefits on fish assemblages by enhancing river connectivity and fluvial habitat availability.

Fish assemblage response to a small dam removal in the Eightmile River system, Connecticut, USA.

PubMed

Poulos, Helen M; Miller, Kate E; Kraczkowski, Michelle L; Welchel, Adam W; Heineman, Ross; Chernoff, Barry

2014-11-01

We examined the effects of the Zemko Dam removal on the Eightmile River system in Salem, Connecticut, USA. The objective of this research was to quantify spatiotemporal variation in fish community composition in response to small dam removal. We sampled fish abundance over a 6-year period (2005-2010) to quantify changes in fish assemblages prior to dam removal, during drawdown, and for three years following dam removal. Fish population dynamics were examined above the dam, below the dam, and at two reference sites by indicator species analysis, mixed models, non-metric multidimensional scaling, and analysis of similarity. We observed significant shifts in fish relative abundance over time in response to dam removal. Changes in fish species composition were variable, and they occurred within 1 year of drawdown. A complete shift from lentic to lotic fishes failed to occur within 3 years after the dam was removed. However, we did observe increases in fluvial and transition (i.e., pool head, pool tail, or run) specialist fishes both upstream and downstream from the former dam site. Our results demonstrate the importance of dam removal for restoring river connectivity for fish movement. While the long-term effects of dam removal remain uncertain, we conclude that dam removals can have positive benefits on fish assemblages by enhancing river connectivity and fluvial habitat availability.

A resilience approach can improve anadromous fish restoration

USGS Publications Warehouse

Waldman, John R.; Wilson, Karen A.; Mather, Martha E.; Snyder, Noah P.

2016-01-01

Most anadromous fish populations remain at low levels or are in decline despite substantial investments in restoration. We explore whether a resilience perspective (i.e., a different paradigm for understanding populations, communities, and ecosystems) is a viable alternative framework for anadromous fish restoration. Many life history traits have allowed anadromous fish to thrive in unimpacted ecosystems but have become contemporary curses as anthropogenic effects increase. This contradiction creates a significant conservation challenge but also makes these fish excellent candidates for a resilience approach. A resilience approach recognizes the need to maintain life history, population, and habitat characteristics that increase the ability of a population to withstand and recover from multiple disturbances. To evaluate whether a resilience approach represents a viable strategy for anadromous fish restoration, we review four issues: (1) how resilience theory can inform anadromous fish restoration, (2) how a resilience-based approach is fundamentally different than extant anadromous fish restoration strategies, (3) ecological characteristics that historically benefited anadromous fish persistence, and (4) examples of how human impacts harm anadromous fish and how a resilience approach might produce more successful outcomes. We close by suggesting new research and restoration directions for implementation of a resilience-based approach.

The offshore benthic fish community

USGS Publications Warehouse

Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

2014-01-01

The offshore benthic fish community will be composed of self-sustaining native fishes characterized by lake trout as the top predator, a population expansion of lake whitefish from northeastern waters to other areas of the lake, and rehabilitated native prey fishes.

Ecosystem consequences of fish parasites

USGS Publications Warehouse

Lafferty, Kevin D.

2008-01-01

In most aquatic ecosystems, fishes are hosts to parasites and, sometimes, these parasites can affect fish biology. Some of the most dramatic cases occur when fishes are intermediate hosts for larval parasites. For example, fishes in southern California estuaries are host to many parasites. The most common of these parasites, Euhaplorchis californiensis, infects the brain of the killifish Fundulus parvipinnis and alters its behaviour, making the fish 10–30 times more susceptible to predation by the birds that serve as its definitive host. Parasites like E. californiensis are embedded in food webs because they require trophic transmission. In the Carpinteria Salt Marsh estuarine food web, parasites dominate the links and comprise substantial amount of biomass. Adding parasites to food webs alters important network statistics such as connectance and nestedness. Furthermore, some free-living stages of parasites are food items for free-living species. For instance, fishes feed on trematode cercariae. Being embedded in food webs makes parasites sensitive to changes in the environment. In particular, fishing and environmental disturbance, by reducing fish populations, may reduce parasite populations. Indirect evidence suggests a decrease in parasites in commercially fished species over the past three decades. In addition, environmental degradation can affect fish parasites. For these reasons, parasites in fishes may serve as indicators of environmental impacts.

Functional implications of Major Histocompatibility (MH) variation using estuarine fish populations.

PubMed

Cohen, Sarah; Tirindelli, Joëlle; Gomez-Chiarri, Marta; Nacci, Diane

2006-12-01

Recently, there has been a dramatic expansion of studies of major histocompatibility complex (MHC) variation aimed at discovering functional differences in immunity across wild populations of diverse vertebrate species. Some species with relatively low genetic diversity or under strong directional selection by pathogens have revealed fascinating cases of MHC allelic disease linkage. More generally in genetically diverse species, however, these linkages may be hard to find. In this paper, we review approaches for assessing functional variation in MHC and discuss their potential use for discovering smaller-scale intraspecific spatial and temporal patterns of MHC variation. Then, we describe and illustrate an approach using the structural model to produce a population composite of variation in antigen-binding regions by mapping population-specific substitutions onto functional regions of the molecule. We are producing models of variation in major histocompatibility (MH) loci for populations of non-migratory fish (killifish, Fundulus heteroclitus) resident at sites that vary dramatically in environmental quality. We discuss the goal of relating MH population variation to functional differences in disease susceptibility such as those inferred by observations of parasitic infection and direct measurement of bacterial challenges in the laboratory. Our study has focused on relatively well-studied killifish populations, including those resident in a highly disturbed, chemically contaminated estuary and nearby less contaminated sites. Population-specific genetic changes at MHC antigen-binding loci are described, and evidence relevant to functional implications of these changes is reviewed. Population-specific patterns of variation in antigen-binding regions in combination with a range of assessments of immune function will provide a powerful new approach to reveal functional changes in MHC.

Impact of climate change on the relict tropical fish fauna of central sahara: threat for the survival of adrar mountains fishes, mauritania.

PubMed

Trape, Sébastien

2009-01-01

Four central Sahara mountainous massifs provide habitats for relict populations of fish. In the Adrar of Mauritania all available data on the presence and distribution of fish come from pre-1960 surveys where five fish species were reported: Barbus pobeguini, Barbus macrops, Barbus mirei, Sarotherodon galilaeus, and Clarias anguillaris. Since 1970, drought has had a severe impact in the Adrar where rainfall decreased by 35%. To investigate whether the relict populations of fish have survived the continuing drought, a study was carried out from 2004 to 2008. An inventory of perennial bodies of water was drawn up using a literature review and analysis of topographical and hydrological maps. Field surveys were carried out in order to locate the bodies of water described in the literature, identify the presence of fish, determine which species were present and estimate their abundance. The thirteen sites where the presence of fish was observed in the 1950s -Ksar Torchane, Ilij, Molomhar, Agueni, Tachot, Hamdoun, Terjit, Toungad, El Berbera, Timagazine, Dâyet el Mbârek, Dâyet et-Tefla, Nkedeï- were located and surveyed. The Ksar Torchane spring -type locality and the only known locality of B. mirei- has dried up at the height of the drought in 1984, and any fish populations have since become extinct there. The Timagazine, Dâyet el Mbârek and Dâyet et-Tefla pools have become ephemeral. The Hamdoun guelta appears to be highly endangered. The fish populations at the other sites remain unchanged. Four perennial pools which are home to populations of B. pobeguini are newly recorded. The tropical relict fish populations of the Adrar mountains of Mauritania appear to be highly endangered. Of thirteen previously recorded populations, four have become extinct since the beginning of the drought period. New fish population extinctions may occur should low levels of annual rainfall be repeated.

Host population density as the major determinant of endoparasite species richness in floodplain fishes of the upper Paraná River, Brazil.

PubMed

Takemoto, R M; Pavanelli, G C; Lizama, M A P; Luque, J L; Poulin, R

2005-03-01

A comparative analysis of parasite species richness was performed across 53 species of fish from the floodplain of the upper Paraná River, Brazil. Values of catch per unit effort, CPUE (number of individuals of a given fish species captured per 1000 m(2) of net during 24 h) were used as a rough measure of population density for each fish species in order to test its influence on endoparasite species richness. The effects of several other host traits (body size, social behaviour, reproductive behaviour, spawning type, trophic category, feeding habits, relative position in the food web, preference for certain habitats and whether the fish species are native or exotic) on metazoan endoparasite species richness were also evaluated. The CPUE was the sole significant predictor of parasite species richness, whether controlling for the confounding influences of host phylogeny and sampling effort or not. The results suggest that in the floodplain of the upper Paraná River (with homogeneous physical characteristics and occurrence of many flood pulses), population density of different host species might be the major determinant of their parasite species richness.

ECONOMIC ASPECTS OF THE FISHING INDUSTRY IN MAINLAND CHINA,

DTIC Science & Technology

the fisheries of China. The report covers mainly the period from 1949 to the present, with a brief survey of the developments prior to that date. The...development of various branches of the fishing industry in the country. The freshwater fishery is based on natural stocks as well as on fishes cultured...in ponds and paddy fields. The marine fishery consists of deep-sea fishing (carried out by government vessels with modern equipment), coastal fishing

Fish consumption, marine omega-3 fatty acids, and incidence of heart failure: a population-based prospective study of middle-aged and elderly men.

PubMed

Levitan, Emily B; Wolk, Alicja; Mittleman, Murray A

2009-06-01

Fatty fish and marine omega-3 fatty acids were associated with lower rates of heart failure (HF) among US elderly, but this has not been confirmed in broader age ranges or other populations where source and type of fish may differ. We therefore conducted a population-based, prospective study of 39 367 middle-aged and older Swedish men. Diet was measured using food-frequency questionnaires. Men were followed for HF through Swedish inpatient and cause-of-death registers from 1 January 1998 to 31 December 2004. We used proportional hazards models adjusted for age and other covariates to estimate hazard ratios (HR). Compared with no consumption, men who ate fatty fish once per week had an HR of 0.88 (95% CI 0.68-1.13). Hazard ratios for consumption two times per week and > or =3 times per week were 0.99 and 0.97, respectively. Hazard ratios across quintiles of marine omega-3 were 1, 0.94 (95% CI 0.74-1.20), 0.67 (95% CI 0.50-0.90), 0.89 (95% CI 0.68-1.16), 1.00 (95% CI 0.77-1.29). In this population, moderate intake of fatty fish and marine omega-3 fatty acids was associated with lower rates of HF, though the association for fish intake was not statistically significant; higher intake was not associated with additional benefit.

Tropical insular fish assemblages are resilient to flood disturbance

USGS Publications Warehouse

Smith, William E.; Kwak, Thomas J.

2015-01-01

Periods of stable environmental conditions, favoring development of ecological communities regulated by density-dependent processes, are interrupted by random periods of disturbance that may restructure communities. Disturbance may affect populations via habitat alteration, mortality, or displacement. We quantified fish habitat conditions, density, and movement before and after a major flood disturbance in a Caribbean island tropical river using habitat surveys, fish sampling and population estimates, radio telemetry, and passively monitored PIT tags. Native stream fish populations showed evidence of acute mortality and downstream displacement of surviving fish. All fish species were reduced in number at most life stages after the disturbance, but populations responded with recruitment and migration into vacated upstream habitats. Changes in density were uneven among size classes for most species, indicating altered size structures. Rapid recovery processes at the population level appeared to dampen effects at the assemblage level, as fish assemblage parameters (species richness and diversity) were unchanged by the flooding. The native fish assemblage appeared resilient to flood disturbance, rapidly compensating for mortality and displacement with increased recruitment and recolonization of upstream habitats.

Inability to demonstrate fish-to-fish transmission of Ichthyophonus from laboratory infected Pacific herring Clupea pallasii to naïve conspecifics

USGS Publications Warehouse

Gregg, J.L.; Grady, C.A.; Friedman, C.S.; Hershberger, P.K.

2012-01-01

The parasite Ichthyophonus is enzootic in many marine fish populations of the northern Atlantic and Pacific Oceans. Forage fishes are a likely source of infection for higher trophic level predators; however, the processes that maintain Ichthyophonus in forage fish populations (primarily clupeids) are not well understood. Lack of an identified intermediate host has led to the convenient hypothesis that the parasite can be maintained within populations of schooling fishes by waterborne fish-to-fish transmission. To test this hypothesis we established Ichthyophonus infections in Age-1 and young-of-the-year (YOY) Pacific herring Clupea pallasii (Valenciennes) via intraperitoneal (IP) injection and cohabitated these donors with naïve conspecifics (sentinels) in the laboratory. IP injections established infection in 75 to 84% of donor herring, and this exposure led to clinical disease and mortality in the YOY cohort. However, after cohabitation for 113 d no infections were detected in naïve sentinels. These data do not preclude the possibility of fish-to-fish transmission, but they do suggest that other transmission processes are necessary to maintain Ichthyophonus in wild Pacific herring populations.

CREATION OF A GEOGRAPHIC INFORMATION SYSTEM TO IDENTIFY AT-RISK POPULATIONS IN NEW JERSEY AND NEW YORK FOR CONSUMPTION OF CONTAMINATED FISH AND SEAFOOD

EPA Science Inventory

Project Objective: To identify at-risk populations, particularly women of child bearing years and young children, for consumption of contaminated fish and seafood via the use of geographically and demographically defined seafood consumption patterns and fish/seafood contaminatio...

Discriminating multi-species populations in biofilms with peptide nucleic acid fluorescence in situ hybridization (PNA FISH).

PubMed

Almeida, Carina; Azevedo, Nuno F; Santos, Sílvio; Keevil, Charles W; Vieira, Maria J

2011-03-29

Our current understanding of biofilms indicates that these structures are typically composed of many different microbial species. However, the lack of reliable techniques for the discrimination of each population has meant that studies focusing on multi-species biofilms are scarce and typically generate qualitative rather than quantitative data. We employ peptide nucleic acid fluorescence in situ hybridization (PNA FISH) methods to quantify and visualize mixed biofilm populations. As a case study, we present the characterization of Salmonella enterica/Listeria monocytogenes/Escherichia coli single, dual and tri-species biofilms in seven different support materials. Ex-situ, we were able to monitor quantitatively the populations of ∼56 mixed species biofilms up to 48 h, regardless of the support material. In situ, a correct quantification remained more elusive, but a qualitative understanding of biofilm structure and composition is clearly possible by confocal laser scanning microscopy (CLSM) at least up to 192 h. Combining the data obtained from PNA FISH/CLSM with data from other established techniques and from calculated microbial parameters, we were able to develop a model for this tri-species biofilm. The higher growth rate and exopolymer production ability of E. coli probably led this microorganism to outcompete the other two [average cell numbers (cells/cm(2)) for 48 h biofilm: E. coli 2,1 × 10(8) (± 2,4 × 10(7)); L. monocytogenes 6,8 × 10(7) (± 9,4 × 10(6)); and S. enterica 1,4 × 10(6) (± 4,1 × 10(5))]. This overgrowth was confirmed by CSLM, with two well-defined layers being easily identified: the top one with E. coli, and the bottom one with mixed regions of L. monocytogenes and S. enterica. While PNA FISH has been described previously for the qualitative study of biofilm populations, the present investigation demonstrates that it can also be used for the accurate quantification and spatial distribution of species in polymicrobial communities

Genetic diversity affects the strength of population regulation in a marine fish.

PubMed

Johnson, D W; Freiwald, J; Bernardi, G

2016-03-01

Variation is an essential feature of biological populations, yet much of ecological theory treats individuals as though they are identical. This simplifying assumption is often justified by the perception that variation among individuals does not have significant effects on the dynamics of whole populations. However, this perception may be skewed by a historic focus on studying single populations. A true evaluation of the extent to which among-individual variation affects the dynamics of populations requires the study of multiple populations. In this study, we examined variation in the dynamics of populations of a live-bearing, marine fish (black surfperch; Embiotoca jacksoni). In collaboration with an organization of citizen scientists (Reef Check California), we were able to examine the dynamics of eight populations that were distributed throughout approximately 700 km of coastline, a distance that encompasses much of this species' range. We hypothesized that genetic variation within a local population would be related to the intensity of competition and to the strength of population regulation. To test this hypothesis, we examined whether genetic diversity (measured by the diversity of mitochondrial DNA haplotypes) was related to the strength of population regulation. Low-diversity populations experienced strong density dependence in population growth rates and population sizes were regulated much more tightly than they were in high-diversity populations. Mechanisms that contributed to this pattern include links between genetic diversity, habitat use, and spatial crowding. On average, low-diversity populations used less of the available habitat and exhibited greater spatial clustering (and more intense competition) for a given level of density (measured at the scale of the reef). Although the populations we studied also varied with respect to exogenous characteristics (habitat complexity, densities of predators, and interspecific competitors), none of these

Prevention and control of fish-borne zoonotic trematodes in fish nurseries, Vietnam.

PubMed

Hedegaard Clausen, Jesper; Madsen, Henry; Murrell, K Darwin; Van, Phan Thi; Thu, Ha Nguyen Thi; Do, Dung Trung; Nguyen Thi, Lan Anh; Nguyen Manh, Hung; Dalsgaard, Anders

2012-09-01

Worldwide, >18 million persons were infected with fish-borne zoonotic trematodes in 2002. To evaluate the effectiveness of interventions for reducing prevalence and intensity of fish-borne zoonotic trematode infections in juvenile fish, we compared transmission rates at nurseries in the Red River Delta, northern Vietnam. Rates were significantly lower for nurseries that reduced snail populations and trematode egg contamination in ponds than for nurseries that did not. These interventions can be used in the development of programs for sustained control of zoonotic trematodes in farmed fish.

Evaluating a fish monitoring protocol using state-space hierarchical models

USGS Publications Warehouse

Russell, Robin E.; Schmetterling, David A.; Guy, Chris S.; Shepard, Bradley B.; McFarland, Robert; Skaar, Donald

2012-01-01

Using data collected from three river reaches in Montana, we evaluated our ability to detect population trends and predict fish future fish abundance. Data were collected as part of a long-term monitoring program conducted by Montana Fish, Wildlife and Parks to primarily estimate rainbow (Oncorhynchus mykiss) and brown trout (Salmo trutta) abundance in numerous rivers across Montana. We used a hierarchical Bayesian mark-recapture model to estimate fish abundance over time in each of the three river reaches. We then fit a state-space Gompertz model to estimate current trends and future fish populations. Density dependent effects were detected in 1 of the 6 fish populations. Predictions of future fish populations displayed wide credible intervals. Our simulations indicated that given the observed variation in the abundance estimates, the probability of detecting a 30% decline in fish populations over a five-year period was less than 50%. We recommend a monitoring program that is closely tied to management objectives and reflects the precision necessary to make informed management decisions.

Early detection of nonnative alleles in fish populations: When sample size actually matters

USGS Publications Warehouse

Croce, Patrick Della; Poole, Geoffrey C.; Payne, Robert A.; Gresswell, Bob

2017-01-01

Reliable detection of nonnative alleles is crucial for the conservation of sensitive native fish populations at risk of introgression. Typically, nonnative alleles in a population are detected through the analysis of genetic markers in a sample of individuals. Here we show that common assumptions associated with such analyses yield substantial overestimates of the likelihood of detecting nonnative alleles. We present a revised equation to estimate the likelihood of detecting nonnative alleles in a population with a given level of admixture. The new equation incorporates the effects of the genotypic structure of the sampled population and shows that conventional methods overestimate the likelihood of detection, especially when nonnative or F-1 hybrid individuals are present. Under such circumstances—which are typical of early stages of introgression and therefore most important for conservation efforts—our results show that improved detection of nonnative alleles arises primarily from increasing the number of individuals sampled rather than increasing the number of genetic markers analyzed. Using the revised equation, we describe a new approach to determining the number of individuals to sample and the number of diagnostic markers to analyze when attempting to monitor the arrival of nonnative alleles in native populations.

Some potentials and limits of the leucocrit test as a fish health assessment method

USGS Publications Warehouse

Wedemeyer, G.A.; Gould, R.W.; Yasutake, W.T.

1983-01-01

The sensitivity of the leucocrit as a stress tolerance and fish health assessment method was evaluated by subjecting juvenile coho salmon, Oncorhynchus kisutch, or steelhead trout, Salmo gairdneri, to standardized crowding, handling, temperature and disease challenges. The leucocrit was a sensitive indicator of the physiological stress resulting from crowding at population densities of 0·2–0·4 kg l−1, and to the stress of handling and to temperature changes. It was relatively insensitive to physiological sampling procedures which supports its continued development as a stress assessment method.In the case of fish diseases, subclinical or active Renibacterium salmoninarum and Yersinia ruckeriinfections had essentially no effect on leucocrit values. In contrast, active Aeromonas salmonicidainfections significantly depressed the leucocrit. However, no change was seen during the subclinical (incubation) phase prior to the development of an epizootic. Thus, the potential of the leucocrit as a fish health assessment method appears limited.

Prevention and Control of Fish-borne Zoonotic Trematodes in Fish Nurseries, Vietnam

PubMed Central

Madsen, Henry; Murrell, K. Darwin; Van, Phan Thi; Thu, Ha Nguyen Thi; Do, Dung Trung; Thi, Lan Anh Nguyen; Manh, Hung Nguyen; Dalsgaard, Anders

2012-01-01

Worldwide, >18 million persons were infected with fish-borne zoonotic trematodes in 2002. To evaluate the effectiveness of interventions for reducing prevalence and intensity of fish-borne zoonotic trematode infections in juvenile fish, we compared transmission rates at nurseries in the Red River Delta, northern Vietnam. Rates were significantly lower for nurseries that reduced snail populations and trematode egg contamination in ponds than for nurseries that did not. These interventions can be used in the development of programs for sustained control of zoonotic trematodes in farmed fish. PMID:22932069

Evolutionary mechanisms shaping the genetic population structure of coastal fish: insight from populations of Coilia nasus in Northwestern Pacific.

PubMed

Gao, Tianxiang; Wan, Zhenzhen; Song, Na; Zhang, Xiumei; Han, Zhiqiang

2014-12-01

A number of evolutionary mechanisms have been suggested for generating significant genetic structuring among marine fish populations in Northwestern Pacific. We used mtDNA control region to assess the factors in shaping the genetic structure of Japanese grenadier anchovy, Coilia nasus, an anadromous and estuarine coastal species, in Northwestern Pacific. Sixty seven individuals from four locations in Northwestern Pacific were sequenced for mitochondrial control region, detecting 61 haplotypes. The length of amplified control region varied from 677 to 754 bp. This length variability was due to the presence of varying numbers of a 38-bp tandemly repeated sequence. Two distinct lineages were detected, which might have diverged during Pleistocene low sea levels. There were strong differences in the geographical distribution of the two lineages. Analyses of molecular variance and the population statistic ΦST revealed significant genetic structure between China and Ariake Bay populations. Based on the frequency distribution of tandem repeat units, significant genetic differentiation was also detected between China and Ariake Bay populations. Isolation by distance seems to be the main factor driving present genetic structuring of C. nasus populations, indicating coastal dispersal pattern in this coastal species. Such an evolutionary process agrees well with some of the biological features characterizing this species.

Long-term changes in deep-water fish populations in the northeast Atlantic: a deeper reaching effect of fisheries?

PubMed

Bailey, D M; Collins, M A; Gordon, J D M; Zuur, A F; Priede, I G

2009-06-07

A severe scarcity of life history and population data for deep-water fishes is a major impediment to successful fisheries management. Long-term data for non-target species and those living deeper than the fishing grounds are particularly rare. We analysed a unique dataset of scientific trawls made from 1977 to 1989 and from 1997 to 2002, at depths from 800 to 4800 m. Over this time, overall fish abundance fell significantly at all depths from 800 to 2500 m, considerably deeper than the maximum depth of commercial fishing (approx. 1600 m). Changes in abundance were significantly larger in species whose ranges fell at least partly within fished depths and did not appear to be consistent with any natural factors such as changes in fluxes from the surface or the abundance of potential prey. If the observed decreases in abundance are due to fishing, then its effects now extend into the lower bathyal zone, resulting in declines in areas that have been previously thought to be unaffected. A possible mechanism is impacts on the shallow parts of the ranges of fish species, resulting in declines in abundance in the lower parts of their ranges. This unexpected phenomenon has important consequences for fisheries and marine reserve management, as this would indicate that the impacts of fisheries can be transmitted into deep offshore areas that are neither routinely monitored nor considered as part of the managed fishery areas.

Fish consumption and risk of stroke, coronary heart disease, and cardiovascular mortality in a Dutch population with low fish intake.

PubMed

Hengeveld, L M; Praagman, J; Beulens, J W J; Brouwer, I A; van der Schouw, Y T; Sluijs, I

2018-05-22

Fish consumption of at least 1 portion/week is related to lower cardiovascular disease (CVD) risk. It is uncertain whether a less frequent intake is also beneficial and whether the type of fish matters. We investigated associations of very low intakes of total, fatty, and lean fish, compared with no fish intake, with 18-year incidences of stroke, coronary heart disease (CHD), and CVD mortality. Data were used from 34,033 participants, aged 20-70 years, of the EPIC-Netherlands cohort. Baseline (1993-1997) fish consumption was estimated using a food frequency questionnaire. We compared any fish consumption, <1 portion/week (<100 g) and ≥1 portion/week to non-fish consumption. During 18 follow-up years, 753 stroke events, 2134 CHD events, and 540 CVD deaths occurred. Among the fish consumers (~92%) median intakes of total, lean, and fatty fish were 57.9, 32.9, and 10.7 g/week, respectively. Any fish consumption compared with non-consumption was not associated with incidences of stroke, CHD, MI, and CVD mortality. Furthermore, consumption of <1 portion/week of total, fatty, or lean fish was not associated with any CVD outcome, as compared with non-consumption. Consumption of ≥1 portion/week of lean fish (HR: 0.70, 95% CI: 0.57-0.86) and of fatty fish (HR: 0.63, 95% CI: 0.39-1.02) were associated with lower incidence of ischaemic stroke. Baseline fish consumption of <1 portion/week, regardless of the type of fish, was unrelated to incidences of stroke, CHD, and CVD mortality in this Dutch cohort. Consumption of ≥1 portion/week of fatty or of lean fish reduced the incidence of ischaemic stroke.

Chapter 3: The status of the cactus ferruginous pygmy-owl in Arizona: Population surveys and habitat assessment

Treesearch

W. Scott Richardson; Jean-Luc E. Cartron; David J. Krueper; Lauren Turner; Thomas H. Skinner

2000-01-01

In 1993, the Arizona Game and Fish Department (AGFD) began formal population surveys in an attempt to document the numbers and distribution of cactus ferruginous pygmy-owls (Glaucidium brasilianum cactorum) in Arizona. Surveys were initiated to gather information on this little-known subspecies which was considered for listing at the time. Prior to...

The scaling of population persistence with carrying capacity does not asymptote in populations of a fish experiencing extreme climate variability.

PubMed

White, Richard S A; Wintle, Brendan A; McHugh, Peter A; Booker, Douglas J; McIntosh, Angus R

2017-06-14

Despite growing concerns regarding increasing frequency of extreme climate events and declining population sizes, the influence of environmental stochasticity on the relationship between population carrying capacity and time-to-extinction has received little empirical attention. While time-to-extinction increases exponentially with carrying capacity in constant environments, theoretical models suggest increasing environmental stochasticity causes asymptotic scaling, thus making minimum viable carrying capacity vastly uncertain in variable environments. Using empirical estimates of environmental stochasticity in fish metapopulations, we showed that increasing environmental stochasticity resulting from extreme droughts was insufficient to create asymptotic scaling of time-to-extinction with carrying capacity in local populations as predicted by theory. Local time-to-extinction increased with carrying capacity due to declining sensitivity to demographic stochasticity, and the slope of this relationship declined significantly as environmental stochasticity increased. However, recent 1 in 25 yr extreme droughts were insufficient to extirpate populations with large carrying capacity. Consequently, large populations may be more resilient to environmental stochasticity than previously thought. The lack of carrying capacity-related asymptotes in persistence under extreme climate variability reveals how small populations affected by habitat loss or overharvesting, may be disproportionately threatened by increases in extreme climate events with global warming. © 2017 The Author(s).

Combined effects of constant sublethal UVA irradiation and elevated temperature on the survival and general metabolism of the convict-cichlid fish, Cichlasoma nigrofasciatum.

PubMed

Winckler, K; Fidhiany, L

1996-04-01

In a previous study we observed that a constant sublethal UVA (320-400 nm) irradiation had a significant effect on the general metabolism in the Convict-cichlid fish (Cichlasoma nigrofasciatum) [Winckler, K. and Fidhiany, L. (1996) J. Photochem. Photobiol. B. Biol. (In press)]. In the present study we show that sublethal UVA irradiation in combination with elevated environmental temperature has a deleterious effect on the same population. The threshold temperature for a sudden increase in mortality of fish receiving an additional sublethal UVA irradiation was 32 degrees C. Prior to the increased mortality, the fish started to avoid the UV light source when the water temperature increased to 31.5 degrees C. Mortality decreased when the temperature declined below 31.5 degrees C. As soon as the temperature changed to normal (adapted) condition (27-29 degrees C) mortality returned to normal levels. In contrast, no changes of fish behavior or mortality were observed at elevated temperature in the nonirradiated reference population. The percentages of fish surviving the high temperature stress were 21.9% for the UVA population and 96.8% for the reference population. The specific oxygen consumption (SOC, average +/- SD) of the survivors from the UVA population during temperature stress was 0.21 +/- 0.05 mg O2 h-1 g body weight (BW)-1, while it was 0.54 +/- 0.11 mg O2 h-1 g BW-1 in the reference population. After the environmental temperature returned below the apparent upper temperature tolerance limit, the oxygen consumption of the UVA population gradually normalized. The SOC measured at different temperature levels--after after the fish passed the temperature stress--showed no significant differences between the UVA population and its reference at 23, 25, 27 and 29 degrees C. However, the SOC at 31 degrees C was significantly (P < 0.05) lower than reference, while at 33 degrees C it was higher (P < 0.10).

Recovery of a US endangered fish.

PubMed

Bain, Mark B; Haley, Nancy; Peterson, Douglas L; Arend, Kristin K; Mills, Kathy E; Sullivan, Patrick J

2007-01-24

More fish have been afforded US Endangered Species Act protection than any other vertebrate taxonomic group, and none has been designated as recovered. Shortnose sturgeon (Acipenser brevirostrum) occupy large rivers and estuaries along the Atlantic coast of North America, and the species has been protected by the US Endangered Species Act since its enactment. Data on the shortnose sturgeon in the Hudson River (New York to Albany, NY, USA) were obtained from a 1970s population study, a population and fish distribution study we conducted in the late 1990s, and a fish monitoring program during the 1980s and 1990s. Population estimates indicate a late 1990s abundance of about 60,000 fish, dominated by adults. The Hudson River population has increased by more than 400% since the 1970s, appears healthy, and has attributes typical for a long-lived species. Our population estimates exceed the government and scientific population recovery criteria by more than 500%, we found a positive trend in population abundance, and key habitats have remained intact despite heavy human river use. Scientists and legislators have called for changes in the US Endangered Species Act, the Act is being debated in the US Congress, and the Act has been characterized as failing to recover species. Recovery of the Hudson River population of shortnose sturgeon suggests the combination of species and habitat protection with patience can yield successful species recovery, even near one of the world's largest human population centers.

Estimates of fish consumption rates for consumers of bought and self-caught fish in Connecticut, Florida, Minnesota, and North Dakota.

PubMed

Moya, Jacqueline; Itkin, Cheryl; Selevan, Sherry G; Rogers, John W; Clickner, Robert P

2008-09-15

Fish consumption rates derived from national surveys may not accurately reflect consumption rates in a particular population such as recreational anglers. Many state and local health agencies in the U.S. have conducted area-specific surveys to study fish consumption patterns in local populations, assess exposure to environmental contaminants, or evaluate compliance with fish advisories. The U.S. Environmental Protection Agency (EPA) has analyzed the raw data from fish consumption surveys in Florida, Connecticut, Minnesota, and North Dakota for the purpose of deriving distributions of fish consumption rates and studying the variables that may be more predictive of high-end consumers. Distributions of fish consumption for different age cohorts, ethnic groups, socioeconomic statuses, types of fish (i.e., freshwater, marine, estuarine), and source of fish (i.e., store-bought versus self-caught) were derived. Consumption of fish and shellfish for those who consume both caught and bought fish is higher than those who reported eating only bought or only self-caught. Mean fish consumption per kilogram of body weight ranged from 0.11 g/kg-day to 2.3 g/kg-day. The highest values were observed in Florida for children 1<6 years of age. The Florida data show a statistically significant increase in the percentage of the population reporting fish and shellfish consumption with an increase in household income and education. This trend was not observed in the other states.

Larval retention and connectivity among populations of corals and reef fishes: history, advances and challenges

NASA Astrophysics Data System (ADS)

Jones, G. P.; Almany, G. R.; Russ, G. R.; Sale, P. F.; Steneck, R. S.; van Oppen, M. J. H.; Willis, B. L.

2009-06-01

The extent of larval dispersal on coral reefs has important implications for the persistence of coral reef metapopulations, their resilience and recovery from an increasing array of threats, and the success of protective measures. This article highlights a recent dramatic increase in research effort and a growing diversity of approaches to the study of larval retention within (self-recruitment) and dispersal among (connectivity) isolated coral reef populations. Historically, researchers were motivated by alternative hypotheses concerning the processes limiting populations and structuring coral reef assemblages, whereas the recent impetus has come largely from the need to incorporate dispersal information into the design of no-take marine protected area (MPA) networks. Although the majority of studies continue to rely on population genetic approaches to make inferences about dispersal, a wide range of techniques are now being employed, from small-scale larval tagging and paternity analyses, to large-scale biophysical circulation models. Multiple approaches are increasingly being applied to cross-validate and provide more realistic estimates of larval dispersal. The vast majority of empirical studies have focused on corals and fishes, where evidence for both extremely local scale patterns of self-recruitment and ecologically significant connectivity among reefs at scales of tens of kilometers (and in some cases hundreds of kilometers) is accumulating. Levels of larval retention and the spatial extent of connectivity in both corals and fishes appear to be largely independent of larval duration or reef size, but may be strongly influenced by geographic setting. It is argued that high levels of both self-recruitment and larval import can contribute to the resilience of reef populations and MPA networks, but these benefits will erode in degrading reef environments.

Characterization of fish assemblages and population structure of freshwater fish in two Tunisian reservoirs: implications for fishery management.

PubMed

Mili, Sami; Ennouri, Rym; Dhib, Amel; Laouar, Houcine; Missaoui, Hechmi; Aleya, Lotfi

2016-06-01

To monitor and assess the state of Tunisian freshwater fisheries, two surveys were undertaken at Ghezala and Lahjar reservoirs. Samples were taken in April and May 2013, a period when the fish catchability is high. The selected reservoirs have different surface areas and bathymetries. Using multi-mesh gill nets (EN 14575 amended) designed for sampling fish in lakes, standard fishing methods were applied to estimate species composition, abundance, biomass, and size distribution. Four species were caught in the two reservoirs: barbel, mullet, pike-perch, and roach. Fish abundance showed significant change according to sampling sites, depth strata, and the different mesh sizes used. From the reservoir to the tributary, it was concluded that fish biomass distribution was governed by depth and was most abundant in the upper water layers. Species size distribution differed significantly between the two reservoirs, exceeding the length at first maturity. Species composition and abundance were greater in Lahjar reservoir than in Ghezala. Both reservoirs require support actions to improve fish productivity.

POPULATION GENETICS AND TOLERANCE TO DIOXIN-LIKE COMPOUNDS OF A MIGRATORY MARINE FISH (MENIDIA MENIDIA) IN POLYCHLORINATED BIPHENOL-CONTAMINTED AND REFERENCES SITES

EPA Science Inventory

We evaluated a population of migratory fish (Menidia menidia) that spawn in New Bedford Harbor (NBH), MA, USA, a U.S. EPA Superfund site with extreme polychlorinated biphenyl (PCB) for evidence of pollution tolerance and population genetic changes. We selected this site because ...

Degrees of Isolation: The Impact of Climate Change on the Dispersal and Population Genetic Structure of Two Antarctic Fish Species

NASA Astrophysics Data System (ADS)

Young, E. F.; Belchier, M.; Meredith, M. P.; Tysklind, N.; Carvalho, G. R.

2016-02-01

Understanding the key drivers of larval dispersal and population connectivity in the marine environment is essential for estimating the potential impacts of climate change on the genetic structure and resilience of populations. Small, isolated and fragmented communities will differ fundamentally in their response and resilience to environmental stress, compared with species that are broadly distributed, abundant, and with a frequent exchange of members. Using a `seascape genetics' approach, combining oceanographic modelling and genetic analyses, we have elucidated the fundamental roles of oceanographic transport and planktonic duration on the connectivity and population genetic structure of two Antarctic fish species with contrasting early life histories, Champsocephalus gunnari and Notothenia rossii. Here, we extend these analyses to consider the impact of rising sea temperatures due to climate change on planktonic dispersal and population connectivity. Using a theoretical approach, the effect of increased water temperatures on mortality rates and species-specific egg and larval phase durations has been incorporated into the models, and the relative impact of these climate-related influences on connectivity and population genetic structure has been investigated. Here we present the key findings of our research and consider the roles of early life history and oceanography in the response of fragmented fish populations to climate change.

Habitat selection by breeding waterbirds at ponds with size-structured fish populations

NASA Astrophysics Data System (ADS)

Kloskowski, Janusz; Nieoczym, Marek; Polak, Marcin; Pitucha, Piotr

2010-07-01

Fish may significantly affect habitat use by birds, either as their prey or as competitors. Fish communities are often distinctly size-structured, but the consequences for waterbird assemblages remain poorly understood. We examined the effects of size structure of common carp ( Cyprinus carpio) cohorts together with other biotic and abiotic pond characteristics on the distribution of breeding waterbirds in a seminatural system of monocultured ponds, where three fish age classes were separately stocked. Fish age corresponded to a distinct fish size gradient. Fish age and total biomass, macroinvertebrate and amphibian abundance, and emergent vegetation best explained the differences in bird density between ponds. Abundance of animal prey other than fish (aquatic macroinvertebrates and larval amphibians) decreased with increasing carp age in the ponds. Densities of ducks and smaller grebes were strongly negatively associated with fish age/size gradient. The largest of the grebes, the piscivorous great crested grebe ( Podiceps cristatus), was the only species that preferred ponds with medium-sized fish and was positively associated with total fish biomass. Habitat selection by bitterns and most rallids was instead strongly influenced by the relative amount of emergent vegetation cover in the ponds. Our results show that fish size structure may be an important cue for breeding habitat choice and a factor affording an opportunity for niche diversification in avian communities.

Consumption of PCB-contaminated sport fish and risk of spontaneous fetal death

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

Mendola, P.; Buck, G.M.; Vena, J.E.

1995-05-01

Spontaneous fetal death has been observed among various mammalian species after exposure to polychlorinated biphenyls (PCBs). Our exposure-based cohort study assessed the relationship between consumption of PCB-contaminated Lake Ontario sport fish and spontaneous fetal death using 1820 multigravid fertile women from the 1990-1991 New York State Angler Cohort Study. Fish consumption data were obtained from food frequency questionnaires and history of spontaneous fetal death from live birth certificates. Analyses were stratified by number of prior pregnancies and controlled for smoking and maternal age. No significant increases in risk for fetal death were observed across four measures of exposure: a lifetimemore » estimate of PCB exposure based on species-specific PCB levels; the number of years of fish consumption; kilograms of sport fish consumed in 1990-1991; and a lifetime estimate of kilograms eaten. A slight risk reduction was seen for women with two prior pregnancies at the highest level of PCB exposure (odds ratio = 0.36; 95% CI, 0.14-0.92) and for women with three or more prior pregnancies with increasing years of fish consumption (odds ratio = 0.97; 95% CI, 0.94-0.99). These findings suggest that consumption of PCB-contaminated sport fish does not increase the risk of spontaneous fetal death. 50 refs., 2 tabs.« less

Expansion of Dreissena into offshore waters of Lake Michigan and potential impacts on fish populations

USGS Publications Warehouse

Bunnell, D.B.; Madenjian, C.P.; Holuszko, J.D.; Adams, J.V.; French, J. R. P.

2009-01-01

Lake Michigan was invaded by zebra mussels (Dreissena polymorpha) in the late 1980s and then followed by quagga mussels (D. bugensis) around 1997. Through 2000, both species (herein Dreissena) were largely restricted to depths less than 50??m. Herein, we provide results of an annual lake-wide bottom trawl survey in Lake Michigan that reveal the relative biomass and depth distribution of Dreissena between 1999 and 2007 (although biomass estimates from a bottom trawl are biased low). Lake-wide mean biomass density (g/m2) and mean depth of collection revealed no trend between 1999 and 2003 (mean = 0.7??g/m2 and 37??m, respectively). Between 2004 and 2007, however, mean lake-wide biomass density increased from 0.8??g/m2 to 7.0??g/m2, because of increased density at depths between 30 and 110??m, and mean depth of collection increased from 42 to 77??m. This pattern was confirmed by a generalized additive model. Coincident with the Dreissena expansion that occurred beginning in 2004, fish biomass density (generally planktivores) declined 71% between 2003 and 2007. Current understanding of fish population dynamics, however, indicates that Dreissena expansion is not the primary explanation for the decline of fish, and we provide a species-specific account for more likely underlying factors. Nonetheless, future sampling and research may reveal a better understanding of the potential negative interactions between Dreissena and fish in Lake Michigan and elsewhere.

Interdecadal changes in the community, population and individual levels of the fish fauna of an extensively modified estuary.

PubMed

Valesini, F J; Cottingham, A; Hallett, C S; Clarke, K R

2017-05-01

This study examined inter-period changes over two to three decades in the fish fauna of an urbanized estuary experiencing rapid population growth and a drying climate (Swan-Canning Estuary, Western Australia). Responses were compared at the fish community level (species composition; 1978-2009 in the shallows and 1993-2009 in deeper waters) and at the population and individual levels of an estuarine indicator species, black bream Acanthopagrus butcheri (biomass-abundance and per capita mass at age, respectively; 1993-2009). All three levels showed distinct shifts from earlier to later periods, but their patterns, sensitivity and breadth differed. Community composition changed markedly in the shallows of the lower-middle estuary between the late 1970s and all later periods and moderately between more disparate periods from 1995 to 2009. Several species trends could be linked to the increasing salinity of the estuary or declining dissolved oxygen levels in its middle-upper reaches. Community changes were, however, small or insignificant in the shallow and deeper waters of the upper estuary and deeper waters of the middle estuary, where environmental perturbations are often most pronounced. This may reflect the resilience of the limited suite of species that typify those reaches and thus their lack of sensitivity in reflecting longer-term change at the coarser level of mean abundance. One such species, the selected indicator, A. butcheri, did, however, show marked temporal changes at both the population and individual levels. Biomass decreased markedly in deeper waters while increasing in the shallows from earlier to later periods, presumably reflecting an onshore movement of fish, and per capita body mass in the 2+, 3+ and 4+ year classes fell steadily over time. Such changes probably indicate deteriorating habitat quality in the deeper waters. The study outcomes provide support for a multifaceted approach to the biomonitoring of estuaries using fishes and highlight

Bioaccumulation of trace metals and total petroleum and genotoxicity responses in an edible fish population as indicators of marine pollution.

PubMed

D'Costa, Avelyno; Shyama, S K; Praveen Kumar, M K

2017-08-01

The present study reports the genetic damage and the concentrations of trace metals and total petroleum hydrocarbons prevailing in natural populations of an edible fish, Arius arius in different seasons along the coast of Goa, India as an indicator of the pollution status of coastal water. Fish were collected from a suspected polluted site and a reference site in the pre-monsoon, monsoon and post-monsoon seasons. Physico-chemical parameters as well as the concentrations of total petroleum hydrocarbons (TPH) and trace metals in the water and sediment as well as the tissues of fish collected from these sites were recorded. The genotoxicity status of the fish was assessed employing the micronucleus test and comet assay. A positive correlation (p<0.001) was observed between the tail DNA and micronuclei in all the fish collected. Multiple regression analysis revealed that tissue and environmental pollutant concentrations and genotoxicity were positively associated and higher in the tissues of the fish collected from the polluted site. Pollution indicators and genotoxicity tests, combined with other physiological or biochemical parameters represent an essential integrated approach for efficient monitoring of aquatic ecosystems in Goa. Copyright © 2017 Elsevier Inc. All rights reserved.

Status and trends of prey fish populations in Lake Superior, 2008

USGS Publications Warehouse

Gorman, Owen T.; Evrard, Lori M.; Cholwek, Gary A.; Falck, Jill M.; Yule, Daniel

2009-01-01

The Great Lakes Science Center has conducted annual daytime bottom trawl surveys of the Lake Superior nearshore (15-80 m bathymetric depth zone) every spring since 1978 to provide a long-term index of relative abundance and biomass of the fish community. Between May 5 and June 14, 2008, 58 stations were sampled around the perimeter of the lake with 12-m wide bottom trawls. Trawls were deployed cross-contour at median start and end depths of 17 and 55 m, respectively. The lakewide mean relative biomass estimate for the entire fish community was 4.61 kg/ha which was similar to that measured in 2007, 4.81 kg/ha. Dominant species in the catch were lake whitefish, rainbow smelt, longnose sucker and cisco, which represented 49, 18, 11, and 7 % of the total community biomass, respectively. Compared to 2007 levels, lake whitefish and cisco biomass increased 35% and 55%, respectively, while bloater and rainbow smelt biomass declined 69% and 41%, respectively. Increased biomass of lake whitefish and decreased biomass in bloater represent trends observed since 2007; however, reversed trends in biomass were observed for cisco and rainbow smelt. Year-class strength for the 2007 cisco cohort (0.20 fish/ha) was below the long-term (1977-2007) average (73.31 fish/ha), as was year-class strength for the 2007 bloater cohort (0.33 fish/ha) compared to the long-term average (11.11 fish/ha). Smelt year class strength (226.26 fish/ha) continues a trend of increasing strength from a 31-year low of 56.75 fish/ha in 2001 and was above the long-term average of 193.81 fish/ha. The 2008 cisco age structure was dominated by age 5 and older fish, which accounted for 82% of the mean relative density. Wisconsin waters continue to be the most productive (mean total community biomass of 17.09 kg/ha), followed by western Ontario (5.40 kg/ha), eastern Ontario (3.08 kg/ha), Michigan (2.82 kg/ha), and Minnesota (0.89 kg/ha).Densities of small (400 mm) hatchery lake trout continued a pattern of decline

The dynamics of a fish stock exploited in two fishing zones.

PubMed

Mchich, R; Auger, P; Raïss, N

2000-12-01

This work presents a specific stock-effort dynamical model. The stocks correspond to two populations of fish moving and growing between two fishery zones. They are harvested by two different fleets. The effort represents the number of fishing boats of the two fleets that operate in the two fishing zones. The bioeconomical model is a set of four ODE's governing the fishing efforts and the stocks in the two fishing areas. Furthermore, the migration of the fish between the two patches is assumed to be faster than the growth of the harvested stock. The displacement of the fleets is also faster than the variation in the number of fishing boats resulting from the investment of the fishing income. So, there are two time scales: a fast one corresponding to the migration between the two patches, and a slow time scale corresponding to growth. We use aggregation methods that allow us to reduce the dimension of the model and to obtain an aggregated model for the total fishing effort and fish stock of the two fishing zones. The mathematical analysis of the model is shown. Under some conditions, we obtain a stable equilibrium, which is a desired situation, as it leads to a sustainable harvesting equilibrium, keeping the stock at exploitable densities.

Factors for improved fish passage waterway construction.

DOT National Transportation Integrated Search

2011-06-01

Streambeds are important fish passageways in Oregon; they provide for the necessary habitats and spawning cycles of a healthy fish population. Oregon state law requires that hydraulic structures located in water properly provide fish passage. Increas...

Introducing a Novel Media to Improve the Recovery of Culturable Bacteria from the Fish Parasite Anisakis spp. larvae (Nematoda: Anisakidae).

PubMed

Svanevik, Cecilie S; Lunestad, Bjørn T

2017-09-01

This paper describes a cultivation method to increase the recovery of bacteria from the marine muscle-invading parasitic nematode larvae of Anisakis spp. These larvae hold a high and complex population of accumulated bacteria, originating from seawater, crustaceans, fish, and marine mammals, all involved in the lifecycle of Anisakis. Two in-house agars based on fish juice prepared by either mechanical or enzymatic degradation of the fish tissue, were made. The Anisakis larvae were homogenised prior to cultivation on the in-house fish juice agars and the bacterial numbers and diversity were compared to those obtained applying the commercially available Marine Agar and Iron Agar Lyngby. Bacterial colonies of unique appearance were subcultured and identified by 16S rRNA gene sequencing. Totally three of twenty identified taxa were found on the in-house fish juice agars only. Fish juice agar prepared enzymatically would be the best supplementary agar, as this agar gave significantly higher heterotrophic plate counts, compared to mechanical preparation. The enzymatically prepared fish juice gave more suitable agar quality, was more resource efficient, and had apparently increased nutrient density and availability.

A fully-stochasticized, age-structured population model for population viability analysis of fish: Lower Missouri River endangered pallid sturgeon example

USGS Publications Warehouse

Wildhaber, Mark L.; Albers, Janice; Green, Nicholas; Moran, Edward H.

2017-01-01

We develop a fully-stochasticized, age-structured population model suitable for population viability analysis (PVA) of fish and demonstrate its use with the endangered pallid sturgeon (Scaphirhynchus albus) of the Lower Missouri River as an example. The model incorporates three levels of variance: parameter variance (uncertainty about the value of a parameter itself) applied at the iteration level, temporal variance (uncertainty caused by random environmental fluctuations over time) applied at the time-step level, and implicit individual variance (uncertainty caused by differences between individuals) applied within the time-step level. We found that population dynamics were most sensitive to survival rates, particularly age-2+ survival, and to fecundity-at-length. The inclusion of variance (unpartitioned or partitioned), stocking, or both generally decreased the influence of individual parameters on population growth rate. The partitioning of variance into parameter and temporal components had a strong influence on the importance of individual parameters, uncertainty of model predictions, and quasiextinction risk (i.e., pallid sturgeon population size falling below 50 age-1+ individuals). Our findings show that appropriately applying variance in PVA is important when evaluating the relative importance of parameters, and reinforce the need for better and more precise estimates of crucial life-history parameters for pallid sturgeon.

Trends in biomarkers, biotic indices, and fish population size revealed contrasting long-term effects of recycled water on the ecological status of a Mediterranean river.

PubMed

Colin, Nicole; Maceda-Veiga, Alberto; Monroy, Mario; Ortega-Ribera, Martí; Llorente, Mireia; de Sostoa, Adolfo

2017-11-01

Recycled water is important for maintaining river flow in semi-arid regions. However, it has ecological risk, as suggested by comparison of habitat and white and red blood cell count in two wild fish species (Barbus meridionalis and Squalius laietanus) before and after an input of recycled water in Ripoll River (NE Spain) in 2009. Due to the lack of normal ranges for blood variables in wild fish, we surveyed seasonally the same river reaches in 2013 to test if blood alterations from 2009 compromised the viability of the fish populations. By examining other indicators of river health in baseline and polluted sites (fish abundance, mass-length relationships, and community indices in fish, diatoms and invertebrates), we tested for the superior utility of blood tests in biomonitoring. The comparison of water quality and scores of diatoms and invertebrate indices between polluted and reference sites showed that polluted sites improved from 2009 to 2013. The abundance of B. meridionalis also increased in polluted sites, but that of S. laietanus declined in 2013 compared to 2009. These results contrast with results of blood analyses in 2009, which suggested that B. meridionalis was more seriously affected by pollution than S. laietanus. The fish index did not reveal the risk of recycled water to fish health, whereas fish mass-length relationships suggested that S. laietanus individuals in 2013 had a better body condition in polluted than in reference sites. Given that the two fish species had opposite results in reference sites, and that the physical habitat was more suitable for B. meridionalis in polluted sites in 2013 than was for S. laietanus, trends in population size are not only explained by pollution. The role of phenology is suggested by peaks in blood disorders during the breeding season. However, more long-term studies combining indicators of river health at the individual and community scales are needed to fully assess the ecological risk of recycled water in

Bottom trawl assessment of Lake Ontario prey fishes

USGS Publications Warehouse

Weidel, Brian C.; Connerton, Michael J.; Holden, Jeremy

2018-01-01

Managing Lake Ontario fisheries in an ecosystem-context requires prey fish community and population data. Since 1978, multiple annual bottom trawl surveys have quantified prey fish dynamics to inform management relative to published Fish Community Objectives. In 2017, two whole-lake surveys collected 341 bottom trawls (spring: 204, fall: 137), at depths from 8-225m, and captured 751,350 fish from 29 species. Alewife were 90% of the total fish catch while Deepwater Sculpin, Round Goby, and Rainbow Smelt comprised the majority of the remaining total catch (3.8, 3.1, and 1.1% respectively). The adult Alewife abundance index for US waters increased in 2017 relative to 2016, however the index for Canadian waters declined. Adult Alewife condition, assessed by the predicted weight of a 165 mm fish (6.5 inches), declined in 2017 from record high values observed in spring 2016. Spring 2017 Alewife condition was slightly less than the 10-year average, but the fall value was well below the 10-year average, likely due to increased Age-1 Alewife abundance. The Age-1 Alewife abundance index was the highest observed in 40 years, and 8-times higher than the previous year. The Age-1 index estimates Alewife reproductive success the preceding year. The warm summer and winter of 2016 likely contributed to the large year class. In contrast the relatively cool 2017 spring and cold winter may result in a lower than average 2017 year class. Abundance indices for Rainbow Smelt, Cisco, and Emerald Shiner either declined or remained at low levels in 2017. Pelagic prey fish diversity continues to be low since a single species, Alewife, dominates the catch. Deepwater Sculpin were the most abundant benthic prey fish in 2017 because Round Goby abundance declined sharply from 2016. Slimy Sculpin density continued to decline and the 2017 biomass index for US waters was the lowest ever observed. Prior to Round Goby proliferation, juvenile Slimy Sculpin comprised ~10% of the Slimy Sculpin catch, but

Factors controlling the early stages of viral haemorrhagic septicaemia epizootics: Low exposure levels, virus amplification and fish-to-fish transmission

USGS Publications Warehouse

Hershberger, P.K.; Gregg, J.L.; Grady, C.A.; Hart, L.M.; Roon, S.R.; Winton, J.R.

2011-01-01

Viral haemorrhagic septicaemia virus, Genogroup IVa (VHSV), was highly infectious to Pacific herring, Clupea pallasii (Valenciennes), even at exposure doses occurring below the threshold of sensitivity for a standard viral plaque assay; however, further progression of the disease to a population-level epizootic required viral amplification and effective fish-to-fish transmission. Among groups of herring injected with VHSV, the prevalence of infection was dose-dependent, ranging from 100%, 75% and 38% after exposure to 19, 0.7 and 0.07 plaque-forming units (PFU)/fish, respectively. Among Pacific herring exposed to waterborne VHSV (140PFUmL-1), the prevalence of infection, geometric mean viral tissue titre and cumulative mortality were greater among cohabitated herring than among cohorts that were held in individual aquaria, where fish-to-fish transmission was prevented. Fish-to-fish transmission among cohabitated herring probably occurred via exposure to shed virus which peaked at 680PFUmL-1; shed virus was not detected in the tank water from any isolated individuals. The results provide insights into mechanisms that initiate epizootic cascades in populations of wild herring and have implications for the design of VHSV surveys in wild fish populations. ?? Published 2011. This article is a US Government work and is in the public domain in the USA.

Effects of Fishing and Fishing Closures on Beach Clams: Experimental Evaluation across Commercially Fished and Non-Fished Beaches before and during Harvesting.

PubMed

Gray, Charles A

2016-01-01

Management responses to reconcile declining fisheries typically include closed areas and times to fishing. This study evaluated this strategy for a beach clam fishery by testing the hypothesis that changes in the densities and size compositions of clams from before to during harvesting would differ between commercially fished and non-fished beaches. Sampling was spatially stratified across the swash and dry sand habitats on each of two commercially fished and two non-fished beaches, and temporally stratified across three six-week blocks: before, early and late harvesting. Small-scale spatio-temporal variability in the densities and sizes of clams was prevalent across both habitats and the components of variation were generally greatest at the lowest levels examined. Despite this, differences in the densities and sizes of clams among individual beaches were evident, but there were few significant differences across the commercially fished versus non-fished beaches from before to during harvesting. There was no evidence of reduced densities or truncated size compositions of clams on fished compared to non-fished beaches, contrasting reports of some other organisms in protected areas. This was probably due to a combination of factors, including the current levels of commercial harvests, the movements and other local-scale responses of clams to ecological processes acting independently across individual beaches. The results identify the difficulties in detecting fishing-related impacts against inherent levels of variability in clam populations. Nevertheless, continued experimental studies that test alternate management arrangements may help refine and determine the most suitable strategies for the sustainable harvesting of beach clams, ultimately enhancing the management of sandy beaches.

Targeting Abundant Fish Stocks while Avoiding Overfished Species: Video and Fishing Surveys to Inform Management after Long-Term Fishery Closures

PubMed Central

2016-01-01

Historically, it has been difficult to balance conservation goals and yield objectives when managing multispecies fisheries that include stocks with various vulnerabilities to fishing. As managers try to maximize yield in mixed-stock fisheries, exploitation rates can lead to less productive stocks becoming overfished. In the late 1990s, population declines of several U.S. West Coast groundfish species caused the U.S. Pacific Fishery Management Council to create coast-wide fishery closures, known as Rockfish Conservation Areas, to rebuild overfished species. The fishery closures and other management measures successfully reduced fishing mortality of these species, but constrained fishing opportunities on abundant stocks. Restrictive regulations also caused the unintended consequence of reducing fishery-dependent data available to assess population status of fished species. As stocks rebuild, managers are faced with the challenge of increasing fishing opportunities while minimizing fishing mortality on rebuilding species. We designed a camera system to evaluate fishes in coastal habitats and used experimental gear and fishing techniques paired with video surveys to determine if abundant species could be caught in rocky habitats with minimal catches of co-occurring rebuilding species. We fished a total of 58 days and completed 741 sets with vertical hook-and-line fishing gear. We also conducted 299 video surveys in the same locations where fishing occurred. Comparison of fishing and stereo-video surveys indicated that fishermen could fish with modified hook-and-line gear to catch abundant species while limiting bycatch of rebuilding species. As populations of overfished species continue to recover along the U.S. West Coast, it is important to improve data collection, and video and fishing surveys may be key to assessing species that occur in rocky habitats. PMID:28002499

Targeting Abundant Fish Stocks while Avoiding Overfished Species: Video and Fishing Surveys to Inform Management after Long-Term Fishery Closures.

PubMed

Starr, Richard M; Gleason, Mary G; Marks, Corina I; Kline, Donna; Rienecke, Steve; Denney, Christian; Tagini, Anne; Field, John C

2016-01-01

Historically, it has been difficult to balance conservation goals and yield objectives when managing multispecies fisheries that include stocks with various vulnerabilities to fishing. As managers try to maximize yield in mixed-stock fisheries, exploitation rates can lead to less productive stocks becoming overfished. In the late 1990s, population declines of several U.S. West Coast groundfish species caused the U.S. Pacific Fishery Management Council to create coast-wide fishery closures, known as Rockfish Conservation Areas, to rebuild overfished species. The fishery closures and other management measures successfully reduced fishing mortality of these species, but constrained fishing opportunities on abundant stocks. Restrictive regulations also caused the unintended consequence of reducing fishery-dependent data available to assess population status of fished species. As stocks rebuild, managers are faced with the challenge of increasing fishing opportunities while minimizing fishing mortality on rebuilding species. We designed a camera system to evaluate fishes in coastal habitats and used experimental gear and fishing techniques paired with video surveys to determine if abundant species could be caught in rocky habitats with minimal catches of co-occurring rebuilding species. We fished a total of 58 days and completed 741 sets with vertical hook-and-line fishing gear. We also conducted 299 video surveys in the same locations where fishing occurred. Comparison of fishing and stereo-video surveys indicated that fishermen could fish with modified hook-and-line gear to catch abundant species while limiting bycatch of rebuilding species. As populations of overfished species continue to recover along the U.S. West Coast, it is important to improve data collection, and video and fishing surveys may be key to assessing species that occur in rocky habitats.

Population Models for Stream Fish Response to Habitat and Hydrologic Alteration: the CVI Watershed Tool. EPA/600/R-04/190

EPA Pesticide Factsheets

Models that predict the responses of fish populations and communities to key habitat characteristics are necessary for CVIs watershed management goals, for determining where to restore and how, as well as evaluating the most probable outcome.

Fish allergy: in review.

PubMed

Sharp, Michael F; Lopata, Andreas L

2014-06-01

Globally, the rising consumption of fish and its derivatives, due to its nutritional value and divergence of international cuisines, has led to an increase in reports of adverse reactions to fish. Reactions to fish are not only mediated by the immune system causing allergies, but are often caused by various toxins and parasites including ciguatera and Anisakis. Allergic reactions to fish can be serious and life threatening and children usually do not outgrow this type of food allergy. The route of exposure is not only restricted to ingestion but include manual handling and inhalation of cooking vapors in the domestic and occupational environment. Prevalence rates of self-reported fish allergy range from 0.2 to 2.29 % in the general population, but can reach up to 8 % among fish processing workers. Fish allergy seems to vary with geographical eating habits, type of fish processing, and fish species exposure. The major fish allergen characterized is parvalbumin in addition to several less well-known allergens. This contemporary review discusses interesting and new findings in the area of fish allergy including demographics, novel allergens identified, immunological mechanisms of sensitization, and innovative approaches in diagnosing and managing this life-long disease.

Gila River Basin Native Fishes Conservation Program

Treesearch

Doug Duncan; Robert W. Clarkson

2013-01-01

The Gila River Basin Native Fishes Conservation Program was established to conserve native fishes and manage against nonnative fishes in response to several Endangered Species Act biological opinions between the Bureau of Reclamation and the U.S. Fish and Wildlife Service on Central Arizona Project (CAP) water transfers to the Gila River basin. Populations of some Gila...

Endangered river fish: factors hindering conservation and restoration

USGS Publications Warehouse

Cooke, Steven J.; Paukert, Craig P.; Hogan, Zeb

2012-01-01

Globally, riverine fish face many anthropogenic threats including riparian and flood plain habitat degradation, altered hydrology, migration barriers, fisheries exploitation, environmental (climate) change, and introduction of invasive species. Collectively, these threats have made riverine fishes some of the most threatened taxa on the planet. Although much effort has been devoted to identifying the threats faced by river fish, there has been less effort devoted to identifying the factors that may hinder our ability to conserve and restore river fish populations and their watersheds. Therefore, we focus our efforts on identifying and discussing 10 general factors (can also be viewed as research and implementation needs) that constrain or hinder effective conservation action for endangered river fish: (1) limited basic natural history information; (2) limited appreciation for the scale/extent of migrations and the level of connectivity needed to sustain populations; (3) limited understanding of fish/river-flow relationships; (4) limited understanding of the seasonal aspects of river fish biology, particularly during winter and/or wet seasons; (5) challenges in predicting the response of river fish and river ecosystems to both environmental change and various restoration or management actions; (6) limited understanding of the ecosystem services provided by river fish; (7) the inherent difficulty in studying river fish; (8) limited understanding of the human dimension of river fish conservation and management; (9) limitations of single species approaches that often fail to address the broader-scale problems; and (10) limited effectiveness of governance structures that address endangered river fish populations and rivers that cross multiple jurisdictions. We suggest that these issues may need to be addressed to help protect, restore, or conserve river fish globally, particularly those that are endangered.

Elucidating dynamic responses of North Pacific fish populations to climatic forcing: Influence of life-history strategy

NASA Astrophysics Data System (ADS)

Yatsu, A.; Aydin, K. Y.; King, J. R.; McFarlane, G. A.; Chiba, S.; Tadokoro, K.; Kaeriyama, M.; Watanabe, Y.

2008-05-01

In order to explore mechanistic linkages between low-frequency ocean/climate variability, and fish population responses, we undertook comparative studies of time-series of recruitment-related productivity and the biomass levels of fish stocks representing five life-history strategies in the northern North Pacific between the 1950s and the present. We selected seven species: Japanese sardine ( Sardinopus melanostictus) and California sardine ( Sardinopus sagax) (opportunistic strategists), walleye pollock ( Theragra chalcogramma, intermediate strategist), pink salmon ( Oncorhynchus gorbuscha, salmonic strategist), sablefish ( Anoplopoma fimbria) and Pacific halibut ( Hippoglossus stenolepis) (periodic strategists) and spiny dogfish ( Squalus acanthias, equilibrium strategist). The responses in terms of productivity of sardine, pink salmon, sablefish and halibut to climatic regime shifts were generally immediate, delayed, or no substantial responses depending on the particular regime shift year and fish stock (population). In walleye pollock, there were some periods of high productivity and low productivity, but not coincidental to climatic regime shifts, likely due to indirect climate forcing impacts on both bottom-up and top-down processes. Biomass of zooplankton and all fish stocks examined, except for spiny dogfish whose data were limited, indicated a decadal pattern with the most gradual changes in periodic strategists and most intensive and rapid changes in opportunistic strategists. Responses of sardine productivity to regime shifts were the most intense, probably due to the absence of density-dependent effects and the availability of refuges from predators when sardine biomass was extremely low. Spiny dogfish were least affected by environmental variability. Conversely, spiny dogfish are likely to withstand only modest harvest rates due to their very low intrinsic rate of increase. Thus, each life-history strategy type had a unique response to climatic

Fishing-induced life-history changes degrade and destabilize harvested ecosystems.

PubMed

Kuparinen, Anna; Boit, Alice; Valdovinos, Fernanda S; Lassaux, Hélène; Martinez, Neo D

2016-02-26

Fishing is widely known to magnify fluctuations in targeted populations. These fluctuations are correlated with population shifts towards young, small, and more quickly maturing individuals. However, the existence and nature of the mechanistic basis for these correlations and their potential ecosystem impacts remain highly uncertain. Here, we elucidate this basis and associated impacts by showing how fishing can increase fluctuations in fishes and their ecosystem, particularly when coupled with decreasing body sizes and advancing maturation characteristic of the life-history changes induced by fishing. More specifically, using an empirically parameterized network model of a well-studied lake ecosystem, we show how fishing may both increase fluctuations in fish abundances and also, when accompanied by decreasing body size of adults, further decrease fish abundance and increase temporal variability of fishes' food resources and their ecosystem. In contrast, advanced maturation has relatively little effect except to increase variability in juvenile populations. Our findings illustrate how different mechanisms underlying life-history changes that may arise as evolutionary responses to intensive, size-selective fishing can rapidly and continuously destabilize and degrade ecosystems even after fishing has ceased. This research helps better predict how life-history changes may reduce fishes' resilience to fishing and ecosystems' resistance to environmental variations.

Resilience and tipping points of an exploited fish population over six decades.

PubMed

Vasilakopoulos, Paraskevas; Marshall, C Tara

2015-05-01

Complex natural systems with eroded resilience, such as populations, ecosystems and socio-ecological systems, respond to small perturbations with abrupt, discontinuous state shifts, or critical transitions. Theory of critical transitions suggests that such systems exhibit fold bifurcations featuring folded response curves, tipping points and alternate attractors. However, there is little empirical evidence of fold bifurcations occurring in actual complex natural systems impacted by multiple stressors. Moreover, resilience of complex systems to change currently lacks clear operational measures with generic application. Here, we provide empirical evidence for the occurrence of a fold bifurcation in an exploited fish population and introduce a generic measure of ecological resilience based on the observed fold bifurcation attributes. We analyse the multivariate development of Barents Sea cod (Gadus morhua), which is currently the world's largest cod stock, over six decades (1949-2009), and identify a population state shift in 1981. By plotting a multivariate population index against a multivariate stressor index, the shift mechanism was revealed suggesting that the observed population shift was a nonlinear response to the combined effects of overfishing and climate change. Annual resilience values were estimated based on the position of each year in relation to the fitted attractors and assumed tipping points of the fold bifurcation. By interpolating the annual resilience values, a folded stability landscape was fit, which was shaped as predicted by theory. The resilience assessment suggested that the population may be close to another tipping point. This study illustrates how a multivariate analysis, supported by theory of critical transitions and accompanied by a quantitative resilience assessment, can clarify shift mechanisms in data-rich complex natural systems. © 2014 John Wiley & Sons Ltd.

Larvivorous fish for preventing malaria transmission

PubMed Central

Walshe, Deirdre P; Garner, Paul; Abdel-Hameed Adeel, Ahmed A; Pyke, Graham H; Burkot, Tom

2013-01-01

the community or the density of the adult anopheline population. In the absence of direct evidence of an effect on transmission, we carried out a secondary analysis on studies that evaluated the effect of introducing larvivorous fish on the density or presence of immature anopheline mosquitoes (larvae and pupae forms) in community water sources to determine whether this intervention has any potential in further research on control of malaria vectors. Data collection and analysis Three review authors screened abstracts and examined potentially relevant studies by using an eligibility form. Two review authors independently extracted data and assessed risk of bias of included studies. If relevant data were unclear or were not reported, we wrote to the trial authors for clarification. We presented data in tables, and we summarized studies that evaluated the effects of fish introduction on anopheline immature density or presence, or both. We used GRADE to summarize evidence quality. We also examined whether the authors of included studies reported on any possible adverse impact of larvivorous fish introduction on non-target native species. Main results We found no reliable studies that reported the effects of introducing larvivorous fish on malaria infection in nearby communities, on entomological inoculation rate, or on adult Anopheles density. For the secondary analysis, we examined the effects of introducing larvivorous fish on the density and presence of anopheline larvae and pupae in community water sources. We included 12 small studies, with follow-up from 22 days to five years. Studies were conducted in a variety of settings, including localized water bodies (such as wells, domestic water containers, fishponds, and pools; six studies), riverbed pools below dams (two studies), rice field plots (three studies), and water canals (two studies). All studies were at high risk of bias. The research was insufficient to determine whether larvivorous fish reduce the density

A stochastic bioenergetics model based approach to translating large river flow and temperature in to fish population responses: The pallid sturgeon example

USGS Publications Warehouse

Wildhaber, Mark L.; Dey, Rima; Wikle, Christopher K.; Moran, Edward H.; Anderson, Christopher J.; Franz, Kristie J.

2015-01-01

In managing fish populations, especially at-risk species, realistic mathematical models are needed to help predict population response to potential management actions in the context of environmental conditions and changing climate while effectively incorporating the stochastic nature of real world conditions. We provide a key component of such a model for the endangered pallid sturgeon (Scaphirhynchus albus) in the form of an individual-based bioenergetics model influenced not only by temperature but also by flow. This component is based on modification of a known individual-based bioenergetics model through incorporation of: the observed ontogenetic shift in pallid sturgeon diet from marcroinvertebrates to fish; the energetic costs of swimming under flowing-water conditions; and stochasticity. We provide an assessment of how differences in environmental conditions could potentially alter pallid sturgeon growth estimates, using observed temperature and velocity from channelized portions of the Lower Missouri River mainstem. We do this using separate relationships between the proportion of maximum consumption and fork length and swimming cost standard error estimates for fish captured above and below the Kansas River in the Lower Missouri River. Critical to our matching observed growth in the field with predicted growth based on observed environmental conditions was a two-step shift in diet from macroinvertebrates to fish.

Effects of Fishing and Fishing Closures on Beach Clams: Experimental Evaluation across Commercially Fished and Non-Fished Beaches before and during Harvesting

PubMed Central

Gray, Charles A.

2016-01-01

Management responses to reconcile declining fisheries typically include closed areas and times to fishing. This study evaluated this strategy for a beach clam fishery by testing the hypothesis that changes in the densities and size compositions of clams from before to during harvesting would differ between commercially fished and non-fished beaches. Sampling was spatially stratified across the swash and dry sand habitats on each of two commercially fished and two non-fished beaches, and temporally stratified across three six-week blocks: before, early and late harvesting. Small-scale spatio-temporal variability in the densities and sizes of clams was prevalent across both habitats and the components of variation were generally greatest at the lowest levels examined. Despite this, differences in the densities and sizes of clams among individual beaches were evident, but there were few significant differences across the commercially fished versus non-fished beaches from before to during harvesting. There was no evidence of reduced densities or truncated size compositions of clams on fished compared to non-fished beaches, contrasting reports of some other organisms in protected areas. This was probably due to a combination of factors, including the current levels of commercial harvests, the movements and other local-scale responses of clams to ecological processes acting independently across individual beaches. The results identify the difficulties in detecting fishing-related impacts against inherent levels of variability in clam populations. Nevertheless, continued experimental studies that test alternate management arrangements may help refine and determine the most suitable strategies for the sustainable harvesting of beach clams, ultimately enhancing the management of sandy beaches. PMID:26731102

Specific IgE to fish extracts does not predict allergy to specific species within an adult fish allergic population

PubMed Central

2014-01-01

Background Fish is an important cause of food allergy. Studies on fish allergy are scarce and in most cases limited to serological evaluation. Our objective was to study patterns of self-reported allergy and tolerance to different commonly consumed fish species and its correlation to IgE sensitization to the same species. Methods Thirty-eight adult fish allergic patients completed a questionnaire regarding atopy, age of onset and symptoms to 13 commonly consumed fish species in the Netherlands (pangasius, cod, herring, eel, hake, pollock, mackerel, tilapia, salmon, sardine, tuna, plaice and swordfish). Specific IgE to these fish extracts were analyzed by ImmunoCAP. Results Median age of onset of fish allergy was 8.5 years. Severe reactions were reported by the majority of patients (n = 20 (53%) respiratory and of these 20 patients, 6 also had cardiovascular symptoms). After diagnosis, 66% of the patients had eliminated all fish from their diet. Allergy to all species ever tried was reported by 59%. In relation to species ever tried, cod (84%) and herring (79%) were the most frequently reported culprit species while hake (57%) and swordfish (55%) were the least frequent. A positive sIgE (value ≥ 0.35 kUA/L) to the culprit species ranged between 50% (swordfish) and 100% (hake). In tolerant patients, a negative sIgE (value < 0.35 kUA/L) ranged from 0% (hake, pollock and swordfish) to 75% (sardine). For cod, the agreement between sIgE test results and reported allergy or tolerance was 82% and 25%, respectively. Sensitization to cod parvalbumin (Gad c 1) was present in 77% of all patients. Conclusion Serological cross-reactivity between fish species is frequent, but in a significant proportion of patients, clinical relevance appears to be limited to only certain species. A well-taken history or food challenge is required for discrimination between allergy to the different fish species. PMID:25225608

Specific IgE to fish extracts does not predict allergy to specific species within an adult fish allergic population.

PubMed

Schulkes, Karlijn Jg; Klemans, Rob Jb; Knigge, Lidy; de Bruin-Weller, Marjolein; Bruijnzeel-Koomen, Carla Afm; Marknell deWitt, Asa; Lidholm, Jonas; Knulst, André C

2014-01-01

Fish is an important cause of food allergy. Studies on fish allergy are scarce and in most cases limited to serological evaluation. Our objective was to study patterns of self-reported allergy and tolerance to different commonly consumed fish species and its correlation to IgE sensitization to the same species. Thirty-eight adult fish allergic patients completed a questionnaire regarding atopy, age of onset and symptoms to 13 commonly consumed fish species in the Netherlands (pangasius, cod, herring, eel, hake, pollock, mackerel, tilapia, salmon, sardine, tuna, plaice and swordfish). Specific IgE to these fish extracts were analyzed by ImmunoCAP. Median age of onset of fish allergy was 8.5 years. Severe reactions were reported by the majority of patients (n = 20 (53%) respiratory and of these 20 patients, 6 also had cardiovascular symptoms). After diagnosis, 66% of the patients had eliminated all fish from their diet. Allergy to all species ever tried was reported by 59%. In relation to species ever tried, cod (84%) and herring (79%) were the most frequently reported culprit species while hake (57%) and swordfish (55%) were the least frequent. A positive sIgE (value ≥ 0.35 kUA/L) to the culprit species ranged between 50% (swordfish) and 100% (hake). In tolerant patients, a negative sIgE (value < 0.35 kUA/L) ranged from 0% (hake, pollock and swordfish) to 75% (sardine). For cod, the agreement between sIgE test results and reported allergy or tolerance was 82% and 25%, respectively. Sensitization to cod parvalbumin (Gad c 1) was present in 77% of all patients. Serological cross-reactivity between fish species is frequent, but in a significant proportion of patients, clinical relevance appears to be limited to only certain species. A well-taken history or food challenge is required for discrimination between allergy to the different fish species.

Restoration and colonization of freshwater mussels and fish in a southeastern United States tailwater

USGS Publications Warehouse

Layzer, J.B.; Scott, E.M.

2006-01-01

The French Broad River originates in North Carolina, flows west into Tennessee and at its confluence with the Holston River forms the Tennessee River. Douglas Dam, located on the French Broad River 52 km above its mouth, is operated primarily for peaking hydroelectric power and flood control. Prior to completion of the dam in 1943, the lower French Broad River contained about 53 species of freshwater mussels and 100 species of fish. By 1977, the fauna in the 52-km-long tailwater was reduced to 12 species of mussels and 42 native species of fish. Improvements in tailwater conditions occurred following initiation of minimum flows in 1987, and consistent reaeration of discharge in 1993. From 1988 to 2002, we sampled three sites (4, 28, and 39 km downstream of the dam) to monitor the fish assemblage. Each year since 1988, we have collected one or more additional species, indicating continued immigration. We collected 82 native and 9 exotic species of fish overall, but the maximum of 67 species in 1 year suggests that some species reside in the tailwater at low densities or all immigrants may not successfully colonize the tailwater. There is limited potential for most extirpated species of mussels to naturally recolonize the tailwater because source populations are isolated. Consequently, 19 754 adult mussels of 19 species were introduced between 1997 and 2000. Survival of translocated mussels has been high, and successful reproduction of at least one translocated species has occurred. Additionally, four mussel species are naturally colonizing the tailwater. Colonization and recruitment of additional mussel species is expected as populations of their host fishes increase. We believe that the improved conditions of the tailwater may allow for the re-establishment of sustaining populations of 30 mussel species of historic occurrence, but the continued operation of Douglas Dam as a peaking hydroelectric project will reduce the probability of successfully reintroducing some

Reproductive potential of Schistocephalus solidus-infected male three-spined stickleback Gasterosteus aculeatus from two U.K. populations.

PubMed

Macnab, V; Katsiadaki, I; Barber, I

2009-11-01

Male three-spined stickleback Gasterosteus aculeatus from two U.K. populations with endemic infections of the cestode Schistocephalus solidus were brought into the laboratory prior to the breeding season and transferred to nesting tanks under conditions designed to stimulate sexual maturation. Nesting and courtship behaviours were scored over a 35 day period, after which fish were euthanized and the liver, spleen, kidney and gonads were weighed. Among G. aculeatus from a park pond in Leicester, U.K., infected males rarely engaged in reproductive behaviours and exhibited reduced indices of sexual development, body condition and general health, with effects being largely independent of relative parasite mass (parasite index, I(P)). In contrast, the reproductive behaviour of infected fish from Kendoon Loch in Dumfriesshire, U.K. appeared to be less severely affected, with infected fish regularly building nests and courting females under laboratory conditions. This was paralleled by a more limited effect of infection on physiological indicators of development, condition and general health. Furthermore, behavioural and physiological variables typically correlated with I(P) among infected fish from this population. Although comparing the performance of infected fish from the two populations directly was difficult due to potentially confounding factors, the results support the findings of recent studies showing that the effects of S. solidus on host reproduction are unlikely to be uniform across G. aculeatus populations. One possibility is that variation in the effects of infection arises from differences in the co-evolutionary association times of G. aculeatus with the parasite.

Successional change in the Lake Superior fish community: population trends in ciscoes, rainbow smelt, and lake trout, 1958-2008

USGS Publications Warehouse

Gorman, Owen T.

2012-01-01

The Lake Superior fish community underwent massive changes in the second half of the 20th century. Those changes are largely reflected in changes in abundance of the adults of principal prey species, the ciscoes (Coregonus spp.), the invasive rainbow smelt (Osmerus mordax), and the principal predator, lake trout (Salvelinus namaycush). To better understand changes in species abundances, a comprehensive series of gillnet and bottom trawl data collected from 1958 to 2008 were examined. In the late 1950s/early 1960s, smelt abundance was at its maximum, wild lake trout was at its minimum, and an abundance of hatchery lake trout was increasing rapidly. The bloater (Coregonus hoyi) was the prevalent cisco in the lake; abundance was more than 300% greater than the next most abundant cisco, shortjaw cisco (C. zenithicus), followed by kiyi (C. kiyi) and lake cisco (C. artedi). By the mid-1960s, abundance of hatchery lake trout was nearing maximum, smelt abundance was beginning to decline, and abundances of all ciscoes declined, but especially that of shortjaw cisco and kiyi. By the late 1970s, recovery of wild lake trout stocks was well underway and abundances of hatchery lake trout and smelt were declining and the ciscoes were reaching their nadir. During 1980–1990, the fish community underwent a dramatic shift in organization and structure. The rapid increase in abundance of wild lake trout, concurrent with a rapid decline in hatchery lake trout, signaled the impending recovery. Rainbow smelt abundance dropped precipitously and within four years, lake cisco and bloater populations rebounded on the heels of a series of strong recruitment events. Kiyi populations showed signs of recovery by 1989, and shortjaw by 2000, though well below historic maximum abundances. High abundance of adult smelt prior to 1980 appears to be the only factor linked to recruitment failure in the ciscoes. Life history traits of the cisco species were examined to better understand their different

Forecasting Tools Point to Fishing Hotspots

NASA Technical Reports Server (NTRS)

2009-01-01

Private weather forecaster WorldWinds Inc. of Slidell, Louisiana has employed satellite-gathered oceanic data from Marshall Space Flight Center to create a service that is every fishing enthusiast s dream. The company's FishBytes system uses information about sea surface temperature and chlorophyll levels to forecast favorable conditions for certain fish populations. Transmitting the data to satellite radio subscribers, FishBytes provides maps that guide anglers to the areas they are most likely to make their favorite catch.

Meeting the Needs for More Fish Through Aquaculture

NASA Astrophysics Data System (ADS)

Giap, D. H.; Lam, T. J.

2015-10-01

Fish is one of the major sources of animal protein. Due to rising world populations, increasing income and urbanization, demand for fish has been increasing. In order to meet the need for more fish, aquaculture has become increasingly important as wild populations and production from capture fisheries have declined due to overfishing and poor management. In recent years, production from aquaculture has increased rapidly to address the shortfalls in capture fisheries, especially in Asia where aquaculture production accounts for about 90% of world aquaculture production by volume. This paper reviews the status of the world’s fish production, provides an update on Asian aquaculture, and highlights developments that are contributing to sustainable fish production, particularly integrated multi-trophic aquaculture and aquaponics.

Acetylcholinesterase inhibition and gill lesions in Rasbora caverii, an indigenous fish inhabiting rice field associated waterbodies in Sri Lanka.

PubMed

Wijeyaratne, W M D N; Pathiratne, Asoka

2006-10-01

The present study was aimed at applying condition factor (CF), brain acetylcholinesterase (AChE) and gill histology as biomarkers for detecting possible exposure/effect induced by pesticides in fish residing rice field associated waterbodies in Sri Lanka. Biomarkers of an indigenous fish, Rasbora caverii collected from five sampling sites including canals near rice fields, a river and a reservoir (the reference site) were evaluated at four sampling stages covering pesticide application periods during rice cultivation season in 2004. Results indicated that CF of the fish did not show significant alterations regardless of the sampling sites or sampling stages. Site specific differences in AChE activities of the fish were not evident either prior to application of pesticides or at 7 days after Paraquat application to the rice fields. Two days after the application of a mixture of Fenthion and Phenthoate to the rice fields, AChE activity of the fish collected from canals near rice fields was significantly depressed (65-75%) compared to the fish in the reference site. The activities remain depressed to 50-56% even at 65 days after the insecticides application. Laboratory studies showed that prior exposure of R. caverii to Paraquat (2 microg l(-1), 7 days) enhanced the extent of inhibition of brain AChE activity induced by Fenthion (3 microg l(-1)) or a mixture of Fenthion (3 microg l(-1)) and Phenthoate (5 microg l(-1)). Gills of fish collected from canals near rice fields exhibited abnormal multiple divisions at the tips of some secondary lamellae in addition to hyperplasia, hypertrophy and club shaped deformities. Results indicate that application of pesticides in rice culture could manifest a threat to native fish populations residing rice field associated waterbodies. The response of brain AChE and histological changes in the gills of R. caverii allowed differentiating sampling sites after insecticide applications to the rice fields. Hence, R. caverii may be

Fishing-induced life-history changes degrade and destabilize harvested ecosystems

NASA Astrophysics Data System (ADS)

Kuparinen, Anna; Boit, Alice; Valdovinos, Fernanda S.; Lassaux, Hélène; Martinez, Neo D.

2016-02-01

Fishing is widely known to magnify fluctuations in targeted populations. These fluctuations are correlated with population shifts towards young, small, and more quickly maturing individuals. However, the existence and nature of the mechanistic basis for these correlations and their potential ecosystem impacts remain highly uncertain. Here, we elucidate this basis and associated impacts by showing how fishing can increase fluctuations in fishes and their ecosystem, particularly when coupled with decreasing body sizes and advancing maturation characteristic of the life-history changes induced by fishing. More specifically, using an empirically parameterized network model of a well-studied lake ecosystem, we show how fishing may both increase fluctuations in fish abundances and also, when accompanied by decreasing body size of adults, further decrease fish abundance and increase temporal variability of fishes’ food resources and their ecosystem. In contrast, advanced maturation has relatively little effect except to increase variability in juvenile populations. Our findings illustrate how different mechanisms underlying life-history changes that may arise as evolutionary responses to intensive, size-selective fishing can rapidly and continuously destabilize and degrade ecosystems even after fishing has ceased. This research helps better predict how life-history changes may reduce fishes’ resilience to fishing and ecosystems’ resistance to environmental variations.

Effects of Pile Driving on the Residency and Movement of Tagged Reef Fish

PubMed Central

Iafrate, Joseph D.; Watwood, Stephanie L.; Reyier, Eric A.; Scheidt, Douglas M.; Dossot, Georges A.; Crocker, Steven E.

2016-01-01

The potential effects of pile driving on fish populations and commercial fisheries have received significant attention given the prevalence of pile driving occurring in coastal habitats throughout the world. Behavioral impacts of sound generated from these activities on fish typically have a greater area of influence than physical injury, and may therefore adversely affect a greater portion of the local population. This study used acoustic telemetry to assess the movement, residency, and survival of 15 sheepshead (Archosargus probatocephalus) and 10 grey snapper (Lutjanus griseus) in Port Canaveral, Florida, USA, in response to 35 days of pile driving at a wharf complex. No obvious signs of mortality or injury to tagged fish were evident from the data. Received sound pressure levels from pile strikes on the interior of the wharf, where reef fish primarily occur, were on average 152–157 dB re 1 μPa (peak). No significant decrease in sheepshead daytime residency was observed during pile driving within the central portion of the wharf and area of highest sound exposure, and no major indicators of displacement from the exposure wharf with the onset of pile driving were observed. There was evidence of potential displacement from the exposure wharf that coincided with the start of pile driving observed for 2 out of 4 grey snapper, along with a decrease in daytime residency for a subset of this species with high site fidelity prior to the event. Results indicate that snapper may be more likely to depart an area of pile driving disturbance more readily than sheepshead, but were less at risk for behavioral impact given the lower site fidelity of this species. PMID:27880786

Population synchrony of a native fish across three Laurentian Great Lakes: Evaluating the effects of dispersal and climate

USGS Publications Warehouse

Bunnell, D.B.; Adams, J.V.; Gorman, O.T.; Madenjian, C.P.; Riley, S.C.; Roseman, E.F.; Schaeffer, J.S.

2010-01-01

Climate and dispersal are the two most commonly cited mechanisms to explain spatial synchrony among time series of animal populations, and climate is typically most important for fishes. Using data from 1978-2006, we quantified the spatial synchrony in recruitment and population catch-per-unit-effort (CPUE) for bloater (Coregonus hoyi) populations across lakes Superior, Michigan, and Huron. In this natural field experiment, climate was highly synchronous across lakes but the likelihood of dispersal between lakes differed. When data from all lakes were pooled, modified correlograms revealed spatial synchrony to occur up to 800 km for long-term (data not detrended) trends and up to 600 km for short-term (data detrended by the annual rate of change) trends. This large spatial synchrony more than doubles the scale previously observed in freshwater fish populations, and exceeds the scale found in most marine or estuarine populations. When analyzing the data separately for within- and between-lake pairs, spatial synchrony was always observed within lakes, up to 400 or 600 km. Conversely, between-lake synchrony did not occur among short-term trends, and for long-term trends, the scale of synchrony was highly variable. For recruit CPUE, synchrony occurred up to 600 km between both lakes Michigan and Huron (where dispersal was most likely) and lakes Michigan and Superior (where dispersal was least likely), but failed to occur between lakes Huron and Superior (where dispersal likelihood was intermediate). When considering the scale of putative bloater dispersal and genetic information from previous studies, we concluded that dispersal was likely underlying within-lake synchrony but climate was more likely underlying between-lake synchrony. The broad scale of synchrony in Great Lakes bloater populations increases their probability of extirpation, a timely message for fishery managers given current low levels of bloater abundance. ?? Springer-Verlag 2009.

Modeling Tribal Exposures to PCBs from Fish Consumption

EPA Science Inventory

Studies have shown that U.S. population continues to be exposed to polychlorinated biphenyls (PCBs), despite the ban ~40 years ago. Fish intake is a major pathway, especially, for high fish-consumption groups. Exposure assessment and risk management considerations for tribal fish...

Correlation set analysis: detecting active regulators in disease populations using prior causal knowledge

PubMed Central

2012-01-01

Background Identification of active causal regulators is a crucial problem in understanding mechanism of diseases or finding drug targets. Methods that infer causal regulators directly from primary data have been proposed and successfully validated in some cases. These methods necessarily require very large sample sizes or a mix of different data types. Recent studies have shown that prior biological knowledge can successfully boost a method's ability to find regulators. Results We present a simple data-driven method, Correlation Set Analysis (CSA), for comprehensively detecting active regulators in disease populations by integrating co-expression analysis and a specific type of literature-derived causal relationships. Instead of investigating the co-expression level between regulators and their regulatees, we focus on coherence of regulatees of a regulator. Using simulated datasets we show that our method performs very well at recovering even weak regulatory relationships with a low false discovery rate. Using three separate real biological datasets we were able to recover well known and as yet undescribed, active regulators for each disease population. The results are represented as a rank-ordered list of regulators, and reveals both single and higher-order regulatory relationships. Conclusions CSA is an intuitive data-driven way of selecting directed perturbation experiments that are relevant to a disease population of interest and represent a starting point for further investigation. Our findings demonstrate that combining co-expression analysis on regulatee sets with a literature-derived network can successfully identify causal regulators and help develop possible hypothesis to explain disease progression. PMID:22443377

Fish farms, parasites, and predators: implications for salmon population dynamics.

PubMed

Krkosek, Martin; Connors, Brendan M; Ford, Helen; Peacock, Stephanie; Mages, Paul; Ford, Jennifer S; Morton, Alexandra; Volpe, John P; Hilborn, Ray; Dill, Lawrence M; Lewis, Mark A

2011-04-01

For some salmon populations, the individual and population effects of sea lice (Lepeophtheirus salmonis) transmission from sea cage salmon farms is probably mediated by predation, which is a primary natural source of mortality of juvenile salmon. We examined how sea lice infestation affects predation risk and mortality of juvenile pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon, and developed a mathematical model to assess the implications for population dynamics and conservation. A risk-taking experiment indicated that infected juvenile pink salmon accept a higher predation risk in order to obtain foraging opportunities. In a schooling experiment with juvenile chum salmon, infected individuals had increased nearest-neighbor distances and occupied peripheral positions in the school. Prey selection experiments with cutthroat trout (O. clarkii) predators indicated that infection reduces the ability of juvenile pink salmon to evade a predatory strike. Group predation experiments with coho salmon (O. kisutch) feeding on juvenile pink or chum salmon indicated that predators selectively consume infected prey. The experimental results indicate that lice may increase the rate of prey capture but not the handling time of a predator. Based on this result, we developed a mathematical model of sea lice and salmon population dynamics in which parasitism affects the attack rate in a type II functional response. Analysis of the model indicates that: (1) the estimated mortality of wild juvenile salmon due to sea lice infestation is probably higher than previously thought; (2) predation can cause a simultaneous decline in sea louse abundance on wild fish and salmon productivity that could mislead managers and regulators; and (3) compensatory mortality occurs in the saturation region of the type II functional response where prey are abundant because predators increase mortality of parasites but not overall predation rates. These findings indicate that predation is an

Population connectivity and genetic structure of burbot (Lota lota) populations in the Wind River Basin, Wyoming

USGS Publications Warehouse

Underwood, Zachary E.; Mandeville, Elizabeth G.; Walters, Annika W.

2016-01-01

Burbot (Lota lota) occur in the Wind River Basin in central Wyoming, USA, at the southwestern extreme of the species’ native range in North America. The most stable and successful of these populations occur in six glacially carved mountain lakes on three different tributary streams and one large main stem impoundment (Boysen Reservoir) downstream from the tributary populations. Burbot are rarely found in connecting streams and rivers, which are relatively small and high gradient, with a variety of potential barriers to upstream movement of fish. We used high-throughput genomic sequence data for 11,197 SNPs to characterize the genetic diversity, population structure, and connectivity among burbot populations on the Wind River system. Fish from Boysen Reservoir and lower basin tributary populations were genetically differentiated from those in the upper basin tributary populations. In addition, fish within the same tributary streams fell within the same genetic clusters, suggesting there is movement of fish between lakes on the same tributaries but that populations within each tributary system are isolated and genetically distinct from other populations. Observed genetic differentiation corresponded to natural and anthropogenic barriers, highlighting the importance of barriers to fish population connectivity and gene flow in human-altered linked lake-stream habitats.

A Teratogenic Deformity Index for Evaluating Impacts of Selenium on Fish Populations

Treesearch

A. Dennis Lemly

1997-01-01

This paper describes a method for using teratogenic deformities in fish as the basis for evaluating impacts of selenium contamination. Teratogenicde deformaties are reliable bioindicators of selenium toxicosis in fish. They are produced in response to dietary exposure of parent fish and subsequent deposition of selenium in eggs. There is a close parallel between...

Effects of fishing and regional species pool on the functional diversity of fish communities.

PubMed

Martins, Gustavo M; Arenas, Francisco; Neto, Ana I; Jenkins, Stuart R

2012-01-01

The potential population and community level impacts of fishing have received considerable attention, but little is known about how fishing influences communities' functional diversity at regional scales. We examined how estimates of functional diversity differed among 25 regions of variable richness and investigated the functional consequences of removing species targeted by commercial fisheries. Our study shows that fishing leads to substantial losses in functional diversity. The magnitude of such loss was, however, reduced in the more speciose regions. Moreover, the removal of commercially targeted species caused a much larger reduction in functional diversity than expected by random species deletions, which was a consequence of the selective nature of fishing for particular species traits. Results suggest that functional redundancy is spatially variable, that richer biotas provide some degree of insurance against the impact of fishing on communities' functional diversity and that fishing predominantly selects for particular species traits. Understanding how fishing impacts community functional diversity is key to predict its effects for biodiversity as well as ecosystem functioning.

Life history, population viability, and the potential for local adaptation in isolated trout populations

Treesearch

K. J. Carim; Y. Vindenes; L. A. Eby; C. Barfoot; L. A. Vollestad

2017-01-01

Habitat loss and fragmentation have caused population decline across taxa through impacts on life history diversity, dispersal patterns, and gene flow. Yet, intentional isolation of native fish populations is a frequently used management strategy to protect against negative interactions with invasive fish species. We evaluated the population viability and genetic...

Life-history diversity and its importance to population stability and persistence of a migratory fish: steelhead in two large North American watersheds.

PubMed

Moore, Jonathan W; Yeakel, Justin D; Peard, Dean; Lough, Jeff; Beere, Mark

2014-09-01

Life-history strategies can buffer individuals and populations from environmental variability. For instance, it is possible that asynchronous dynamics among different life histories can stabilize populations through portfolio effects. Here, we examine life-history diversity and its importance to stability for an iconic migratory fish species. In particular, we examined steelhead (Oncorhynchus mykiss), an anadromous and iteroparous salmonid, in two large, relatively pristine, watersheds, the Skeena and Nass, in north-western British Columbia, Canada. We synthesized life-history information derived from scales collected from adult steelhead (N = 7227) in these watersheds across a decade. These migratory fishes expressed 36 different manifestations of the anadromous life-history strategy, with 16 different combinations of freshwater and marine ages, 7·6% of fish performing multiple spawning migrations, and up to a maximum of four spawning migrations per lifetime. Furthermore, in the Nass watershed, various life histories were differently prevalent through time - three different life histories were the most prevalent in a given year, and no life history ever represented more than 45% of the population. These asynchronous dynamics among life histories decreased the variability of numerical abundance and biomass of the aggregated population so that it was > 20% more stable than the stability of the weighted average of specific life histories: evidence of a substantial portfolio effect. Year of ocean entry was a key driver of dynamics; the median correlation coefficient of abundance of life histories that entered the ocean the same year was 2·5 times higher than the median pairwise coefficient of life histories that entered the ocean at different times. Simulations illustrated how different elements of life-history diversity contribute to stability and persistence of populations. This study provides evidence that life-history diversity can dampen fluctuations in

Biology of extinction risk in marine fishes

PubMed Central

Reynolds, John D; Dulvy, Nicholas K; Goodwin, Nicholas B; Hutchings, Jeffrey A

2005-01-01

We review interactions between extrinsic threats to marine fishes and intrinsic aspects of their biology that determine how populations and species respond to those threats. Information is available on the status of less than 5% of the world's approximately 15 500 marine fish species, most of which are of commercial importance. By 2001, based on data from 98 North Atlantic and northeast Pacific populations, marine fishes had declined by a median 65% in breeding biomass from known historic levels; 28 populations had declined by more than 80%. Most of these declines would be sufficient to warrant a status of threatened with extinction under international threat criteria. However, this interpretation is highly controversial, in part because of a perception that marine fishes have a suite of life history characteristics, including high fecundity and large geographical ranges, which might confer greater resilience than that shown by terrestrial vertebrates. We review 15 comparative analyses that have tested for these and other life history correlates of vulnerability in marine fishes. The empirical evidence suggests that large body size and late maturity are the best predictors of vulnerability to fishing, regardless of whether differences among taxa in fishing mortality are controlled; there is no evidence that high fecundity confers increased resilience. The evidence reviewed here is of direct relevance to the diverse criteria used at global and national levels by various bodies to assess threat status of fishes. Simple life history traits can be incorporated directly into quantitative assessment criteria, or used to modify the conclusions of quantitative assessments, or used as preliminary screening criteria for assessment of the ∼95% of marine fish species whose status has yet to be evaluated either by conservationists or fisheries scientists. PMID:16243696

Biology of extinction risk in marine fishes.

PubMed

Reynolds, John D; Dulvy, Nicholas K; Goodwin, Nicholas B; Hutchings, Jeffrey A

2005-11-22

We review interactions between extrinsic threats to marine fishes and intrinsic aspects of their biology that determine how populations and species respond to those threats. Information is available on the status of less than 5% of the world's approximately 15500 marine fish species, most of which are of commercial importance. By 2001, based on data from 98 North Atlantic and northeast Pacific populations, marine fishes had declined by a median 65% in breeding biomass from known historic levels; 28 populations had declined by more than 80%. Most of these declines would be sufficient to warrant a status of threatened with extinction under international threat criteria. However, this interpretation is highly controversial, in part because of a perception that marine fishes have a suite of life history characteristics, including high fecundity and large geographical ranges, which might confer greater resilience than that shown by terrestrial vertebrates. We review 15 comparative analyses that have tested for these and other life history correlates of vulnerability in marine fishes. The empirical evidence suggests that large body size and late maturity are the best predictors of vulnerability to fishing, regardless of whether differences among taxa in fishing mortality are controlled; there is no evidence that high fecundity confers increased resilience. The evidence reviewed here is of direct relevance to the diverse criteria used at global and national levels by various bodies to assess threat status of fishes. Simple life history traits can be incorporated directly into quantitative assessment criteria, or used to modify the conclusions of quantitative assessments, or used as preliminary screening criteria for assessment of the approximately 95% of marine fish species whose status has yet to be evaluated either by conservationists or fisheries scientists.

36 CFR 2.3 - Fishing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... impact populations of native species adversely, and park management plans do not call for elimination of... time of catching the person did not possess the legal limit of fish. (8) Fishing from motor road bridges, from or within 200 feet of a public raft or float designated for water sports, or within the...

Blood pressure, serum lipids, and fatty acids in populations on a lake-fish diet or on a vegetarian diet in Tanzania.

PubMed

Pauletto, P; Puato, M; Angeli, M T; Pessina, A C; Munhambo, A; Bittolo-Bon, G; Galli, C

1996-03-01

Major risk factors for coronary heart disease were assessed in two populations of Tanzania, one on a fish diet (FD) living along the coast of Lake Nyasa, and the other, mainly on a vegetarian diet (VD), living in a farming area. Lower blood pressure values were found in the FD subjects (n = 618) vs. VD (n = 618) (systolic blood pressure, SBP, 120 +/- 15 vs. 135 +/- 20, P < 0.01; diastolic blood pressure, DBP, 70 +/- 9 vs. 78 +/- 11, P < 0.01, respectively). In an FD subgroup (n = 61), total cholesterol (TC) (122 vs. 136 mg/dL, P < 0.01); triglycerides (TG) (82 vs. 105 mg/dL, P < 0.01); and lipoprotein (a) [Lp(a)] (19.9 +/- 18.4 vs. 32.3 +/- 22.4, P < 0.001) were lower than in a VD subgroup (n = 55). Serum fatty acids (FA) in the FD subgroup were as follows: eicosapentaenoic acid (EPA) (20:5) 2.48 vs. 0.72%, docosahexaenoic acid (DHA) (22:6) 5.93 vs. 1.49%, vs. the VD, respectively. Arachidonic acid (AA) (20:4n-6) also was higher in the FD vs. the VD group (9.85 vs. 8.30%, P < 0.05), whereas 18:2n-6 was about double (23.97 and 14.85%) in VD vs. FD. The peculiar serum FA pattern in FD reflected the FA of dietary fish. In fact, in four main species of lake fish, DHA was 8-19%, higher than EPA (1.8-4.2%), in contrast with the situation in cold-water fish, and AA was 5.8-8%, higher than in cold-water fish. The data, obtained in populations strictly on natural, unprocessed, low-fat diets, show that a diet based on freshwater fish results in lower BP, serum TC, TG, and Lp(a), and suggests that serum AA is not reduced when the major dietary n-3 is DNA rather than EPA.

Simulating fish assemblages in riverine networks

EPA Science Inventory

We describe a modeling approach for simulating assemblages of fish in riverine landscapes. The approach allows a user to determine the grain and extent of river networks within which fish populations reproduce, move, and survive in response to both environmental drivers and assem...

Forestry practices and aquatic biodiversity: Fish

USGS Publications Warehouse

Gresswell, Robert E.

2005-01-01

In the Pacific Northwest, fish communities are found in a diverse array of aquatic habitats ranging from the large coastal rivers of the temperate rainforests, to the fragmented and sometimes ephemeral streams of the xeric interior basins, and high-elevation streams and lakes in the mountainous areas (Rieman et al. 2003). Only high-elevation lakes and streams isolated above barriers to fish passage remained historically devoid of fish because they were never invaded following Pleistocene glaciation (Smith 1981). Despite this widespread distribution and once great population abundances, taxonomic diversity of fishes in these forested systems is naturally lower than in aquatic habitats in the eastern U.S. (Reeves, Bisson, and Dambacher 1998). Interactions among factors that influence species richness in aquatic systems (e.g., basin size, long-term stability of habitat, and barriers to colonization; Smith 1981) continue to influence the occurrence and persistence of fishes in these systems today. Consequently, the larger low-elevation rivers and estuaries support the greatest variety of fish species. In the high-elevation tributary streams, fish communities are less complex because these aquatic systems were less climatically and geologically stable, and fish populations were smaller and more prone to local extirpation. Furthermore, barriers to fish passage inhibited dispersal and colonization (Smith 1981). Streams in forested landscapes generally support salmon and trout, Oncorhynchus spp., whitefish Prosopium spp., sculpins Cottus spp., suckers Catostomus spp., and minnows (Cyprinidae), but in some of the colder streams, chars (e.g., Salvelinus confluentus and Salvelinus malma) and lampreys (Petromyzontidae)may also occur (Rieman et al. 2003).Although biodiversity defined in terms of fish species richness is low in the Pacific Northwest, intraspecific variability is high, and polytypic fish species are common in the diverse aquatic habitats of the region. For

Correlations of fish intake and plasma docosahexaenoic acid levels with each congener of PCDDs/PCDFs/dioxin-like PCBs in blood from the Japanese population.

PubMed

Kitayama, Atsushi; Arisawa, Kokichi; Uemura, Hirokazu; Hiyoshi, Mineyoshi; Takami, Hidenobu; Sawachika, Fusakazu; Yamaguchi, Miwa; Nakamoto, Mariko; Hasegawa, Manabu; Tanto, Masaharu; Shima, Masayuki; Sumiyoshi, Yoshio; Morinaga, Kenji; Kodama, Kazunori; Suzuki, Taka-Ichiro; Nagai, Masaki; Satoh, Hiroshi

2011-12-01

The purpose of the present study was to investigate the factors associated with blood levels of each congener of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) in the Japanese population. A cross-sectional study was performed on 1,656 subjects (755 men and 901 women) aged 15-73 years, who were living in 90 different areas of 30 prefectures in Japan. Blood levels of 29 PCDD, PCDF, and DL-PCB congeners were determined by high-resolution gas chromatography/mass spectrometry. In addition, a questionnaire survey on life style, including dietary habit, was carried out. The median total toxicity equivalent (TEQ) was 17 pgTEQ/g lipid. After adjustment for age, sex, body mass index, smoking habit, and consumption of other food groups, six PCDDs/PCDFs with 4-6 substituted chlorine atoms and 10 DL-PCBs, but not HeptaCDD/F or OctaCDD, showed significant positive correlations with the frequency of intake of fish and shellfish. Furthermore, significant positive relationships were also found between plasma levels of docosahexaenoic acid (DHA), a biomarker of fish intake, and 10 PCDDs/PCDFs with 4-6 chlorine atoms and 10 DL-PCBs. The partial correlation coefficients with plasma DHA were significantly higher for DL-PCBs than for PCDDs/PCDFs, and partial correlation coefficients for PCDDs/PCDFs significantly decreased with increasing number of chlorine atoms (Spearman r = -0.80, P = 0.001). Blood levels of PCDDs/PCDFs with 4-6 chlorine atoms and DL-PCBs were positively associated with fish intake in the Japanese population. These results may be explained by the higher degree of bioaccumulation of these congeners in fish and shellfish in the ecosystem, and the high consumption of fish among the Japanese population.

COLLAPSE OF A FISH POPULATION FOLLOWING EXPOSURE TO A SYNTHETIC ESTROGEN

EPA Science Inventory

Municipal wastewaters are a complex mixture containing estrogens and estrogen mimics that are known to affect the reproductive health of wild fishes. Male fishes downstream of some wastewater outfalls produce vitellogenin (VTG) (a protein normally synthesized by females during oo...

Fishing and temperature effects on the size structure of exploited fish stocks.

PubMed

Tu, Chen-Yi; Chen, Kuan-Ting; Hsieh, Chih-Hao

2018-05-08

Size structure of fish stock plays an important role in maintaining sustainability of the population. Size distribution of an exploited stock is predicted to shift toward small individuals caused by size-selective fishing and/or warming; however, their relative contribution remains relatively unexplored. In addition, existing analyses on size structure have focused on univariate size-based indicators (SBIs), such as mean length, evenness of size classes, or the upper 95-percentile of the length frequency distribution; these approaches may not capture full information of size structure. To bridge the gap, we used the variation partitioning approach to examine how the size structure (composition of size classes) responded to fishing, warming and the interaction. We analyzed 28 exploited stocks in the West US, Alaska and North Sea. Our result shows fishing has the most prominent effect on the size structure of the exploited stocks. In addition, the fish stocks experienced higher variability in fishing is more responsive to the temperature effect in their size structure, suggesting that fishing may elevate the sensitivity of exploited stocks in responding to environmental effects. The variation partitioning approach provides complementary information to univariate SBIs in analyzing size structure.

Determinants of Adoption of Improved Fish Production Technologies among Fish Farmers in Delta State, Nigeria

ERIC Educational Resources Information Center

Ofuoku, A. U.; Olele, N. F.; Emah, G. N.

2008-01-01

This study was conducted to isolate the determinants of improved fish production technologies in Delta State, Nigeria. Data were collected from a sample population of 250 fish farmers from ten randomly selected Local Government Areas of Delta State. The data were elicited from respondents with the use of structured interview schedule while…

Study on polychlorobiphenyl serum levels in French consumers of freshwater fish.

PubMed

Desvignes, Virginie; Volatier, Jean-Luc; de Bels, Frédéric; Zeghnoun, Abdelkrim; Favrot, Marie-Christine; Marchand, Philippe; Le Bizec, Bruno; Rivière, Gilles; Leblanc, Jean-Charles; Merlo, Mathilde

2015-02-01

Polychlorobiphenyls (PCBs) are persistent pollutants that are widespread in the environment and in foodstuffs, particularly in freshwater fish, which frequently exceed the maximum levels set by European regulations. First, we describe the consumption of freshwater fish and serum PCB levels in French anglers, a population expected to have the highest level of dietary PCB exposure. Second, we investigated whether there is a statistical relationship between serum PCB levels and the angler consumption of freshwater fish with high PCB bioaccumulation potential (PCB-BP(+) freshwater fish) in order to make recommendations with regard to safe consumption of freshwater fish. We conducted a survey of anglers from six sites with contrasting PCB contamination levels. The survey included a food consumption frequency questionnaire and blood samples were taken to assess serum PCB levels. We used a regression model to determine the main factors contributing to serum PCB levels. Consumption of PCB-BP(+) freshwater fish was relatively infrequent. Serum PCB levels of the study population and of women of childbearing age were in the same range as those observed in the French population and in neighbouring European countries, but higher than in the North American population. The two factors with the highest positive association with serum PCB levels were age (R(2)=61%) and the consumption of PCB-BP(+) freshwater fish (R(2)=2%). Using the regression model, we calculated, for several scenarios depending on the age and gender of the population, the maximum annual frequencies for PCB-BP(+) freshwater fish consumption that do not exceed the critical body burden threshold. Following the results of this study, the French agency for food, environmental and occupational health and safety (ANSES) issued an opinion and recommended some specific maximum freshwater fish consumption frequencies to protect the French general population. Copyright © 2014 Elsevier B.V. All rights reserved.

Data-Limited Population-Status Evaluation of Two Coastal Fishes in Southern Angola Using Recreational Catch Length-Frequency Data.

PubMed

Beckensteiner, Jennifer; Kaplan, David M; Potts, Warren M; Santos, Carmen V; O'Farrell, Michael R

2016-01-01

Excessive truncation of a population's size structure is often identified as an important deleterious effect of exploitation, yet the effect on population persistence of size-structure truncation caused by exploitation is often not quantified due to data limitations. In this study, we estimate changes in eggs per recruit (EPR) using annual length-frequency samples over a 9 year period to assess persistence of the two most important recreational fishes in southern Angola: west coast dusky kob (Argyrosomus coronus) and leerfish (Lichia amia). Using a length- and age-structured model, we improve on an existing method to fit this type of model to length-frequency data and estimate EPR. The objectives of the methodological changes are to add flexibility and robustness to the approach for assessing population status in data-limited situations. Results indicate that dusky kob presents very low levels of EPR (5%-10% of the per recruit reproductive capacity in the absence of fishing) in 2013, whereas large inter-annual variability in leerfish estimates suggest caution must be applied when drawing conclusions about its exploitation status. Using simulated length frequency data with known parameter values, we demonstrate that recruitment decline due to overexploitation leads to overestimation of EPR values. Considering the low levels of EPR estimated for the study species, recruitment limitation is not impossible and true EPR values may be even lower than our estimates. It is, therefore, likely that management action, such as the creation of Marine Protected Areas, is needed to reconstitute the west coast dusky kob population.

Fishing-gear restrictions and biomass gains for coral reef fishes in marine protected areas.

PubMed

Campbell, Stuart J; Edgar, Graham J; Stuart-Smith, Rick D; Soler, German; Bates, Amanda E

2018-04-01

Considerable empirical evidence supports recovery of reef fish populations with fishery closures. In countries where full exclusion of people from fishing may be perceived as inequitable, fishing-gear restrictions on nonselective and destructive gears may offer socially relevant management alternatives to build recovery of fish biomass. Even so, few researchers have statistically compared the responses of tropical reef fisheries to alternative management strategies. We tested for the effects of fishery closures and fishing gear restrictions on tropical reef fish biomass at the community and family level. We conducted 1,396 underwater surveys at 617 unique sites across a spatial hierarchy within 22 global marine ecoregions that represented 5 realms. We compared total biomass across local fish assemblages and among 20 families of reef fishes inside marine protected areas (MPAs) with different fishing restrictions: no-take, hook-and-line fishing only, several fishing gears allowed, and sites open to all fishing gears. We included a further category representing remote sites, where fishing pressure is low. As expected, full fishery closures, (i.e., no-take zones) most benefited community- and family-level fish biomass in comparison with restrictions on fishing gears and openly fished sites. Although biomass responses to fishery closures were highly variable across families, some fishery targets (e.g., Carcharhinidae and Lutjanidae) responded positively to multiple restrictions on fishing gears (i.e., where gears other than hook and line were not permitted). Remoteness also positively affected the response of community-level fish biomass and many fish families. Our findings provide strong support for the role of fishing restrictions in building recovery of fish biomass and indicate important interactions among fishing-gear types that affect biomass of a diverse set of reef fish families. © 2017 Society for Conservation Biology.

Relationship between mercury levels in hair and fish consumption in a population living near a hydroelectric tropical dam.

PubMed

Marrugo-Negrete, José Luis; Ruiz-Guzmán, Javier Alonso; Díez, Sergi

2013-02-01

In the present study, total mercury (T-Hg) concentrations were assessed in human hair samples (n = 76) and fish muscle (n = 33) collected at Urrá dam, upstream Sinú river, northwestern Colombia. Based on interviews with study participants, weekly intakes of total mercury (WIT-Hg) and methylmercury (WIMeHg) by fish consumption were also estimated. T-Hg concentrations in hair samples ranged from 0.40 to 24.56 μg/g dw. The highest concentrations were recorded in children (CH) (2-15 years old, n = 24) with significant differences (p < 0.05) with respect to women of childbearing age (WCHA) (16-49 years old, n = 29) and the rest of the population (RP) (n = 23), which were not significantly different. The highest T-Hg concentrations in muscle tissue were recorded in the carnivorous fish (0.65-2.25 μg/g wet weight, ww), with significant differences (p < 0.05) compared to non-carnivorous fish (0.16-0.54 μg/g ww). WIT-Hg recorded the highest values in CH (2.18-50.41 μg/kg/week), with significant differences (p < 0.05) with respect to WCHA (2.02-23.54 μg/kg/week) and RP (1.09-24.71 μg/kg/week), which were not significantly different. Correlation analysis showed a significant relationship between weekly fish consumption and hair T-Hg in CH (r = 0.37, p < 0.05) and WCHA (r = 0.44, p < 0.05). This association was also observed with the number of days per week with fish consumption in CH (r = 0.37, p < 0.05) and WCHA (r = 0.45, p < 0.05). These results suggest that Hg exposure in people inhabiting the Urrá dam should be carefully monitored, particularly in vulnerable groups such as CH and WCHA.

Endangered fish threatened by Asian fish tapeworm

USGS Publications Warehouse

Cole, Rebecca A.

2004-01-01

The Asian fish tapeworm, an exotic parasite, has invaded the endangered humpback chub (Gila cypha) population from the Colorado and Little Colorado Rivers in Grand Canyon, Arizona. This parasite causes disease and death in carp in aquaculture settings and may retard growth in hatchery-reared roundtail chub (Gila robusta). Other consequences include destruction and dysfunction of the intestinal lining and adverse changes to certain blood parameters. Introduced into the U.S. in the 1970s with imported grass carp (Ctenopharyngodon idella), the Asian fish tapeworm (Bothriocephalus acheilognathi) was discovered in the Little Colorado River (LCR) by 1990. The LCR is the main tributary to the Colorado River in Grand Canyon and is an important spawning area for humpback chub.

Temporal changes in fishing motivation among fishing club anglers in the United States

USGS Publications Warehouse

Schramm, H.L.; Gerard, P.D.

2004-01-01

Responses from freshwater anglers (n = 4287) to a nationwide survey of the US fishing club members were used to assess differences in the importance of 16 fishing motivation items between 1987 and 1997, dates that preceded and followed a period of substantial decline in recreational fishing participation in the US. Comparison of respondents' motivations for fishing in 1997 and 10 years earlier indicated consistency in the paramount importance of being outdoors, relaxation and the experience of the catch. However, the importance of family recreation and being with friends in 1987 were replaced by escape items in 1997. Anglers with fewer dependents and living in areas with higher population density were more likely to decrease the importance of family recreation. Younger anglers were more likely to decrease the importance of being with friends. Anglers who had higher household income, fished more and had higher fishing expenditures were more likely to decrease the importance of obtaining fish to eat. The results of this study suggest that managers should be less concerned about angler opposition to liberal regulations that allow anglers to harvest fish, and that heightened efforts to recruit and retain recreational anglers, which presently focus on family recreation, should be broadened to include outdoor experience, relaxation and escape aspects of fishing. ?? 2004 Blackwell Publishing Ltd.

Method for Differentiation between Fresh and Frozen-thawed Fish

NASA Astrophysics Data System (ADS)

Kitamikado, Manabu; Yoshioka, Keiko

In Japan fresh fish has a much higher market price than that for frozen-thawed fish. However, a large number of frozen-thawed fish are sold without being differentiated from fresh fish. We discuss here the differentiation methods described in literatures and our works in the search for such a method. We used the opacity of crystalline lens and the destruction of red blood cells as the index for the differentiation, in addition to the activity of neutral β-N-acetylglucosaminidase in blood. Thus, a fluorometric method and a rapid paper test method were developed based on measurement of the activity of this enzyme. This enzyme, found in fish red blood cells, was inactive in intact cells but was activated when cells were disrupted by freezing, and thawing. Both methods were applicable for testing most commom edible fish prior to filleting and required about 20 min using a UV-lamp.

Mercury in Forage Fish from Mexico and Central America: Implications for Fish-Eating Birds.

PubMed

Elliott, John E; Kirk, David A; Elliott, Kyle H; Dorzinsky, Jessica; Lee, Sandi; Inzunza, Ernesto Ruelas; Cheng, Kimberly M T; Scheuhammer, Tony; Shaw, Patrick

2015-11-01

Mercury (Hg) is a global contaminant of aquatic food chains. Aquatic birds, such as the osprey (Pandion haliaetus), with migratory populations breeding in Canada and the northern United States and wintering in the Central and South America, can be exposed to mercury on both the breeding and wintering ranges. We examined Hg levels in 14 fish taxa from 24 osprey wintering sites identified from satellite telemetry. Our main goal was to determine whether fish species that feature in the diet of overwintering and resident fish-eating birds reached toxicity thresholds for Hg. Mean Hg levels in fish whole carcasses ranged from a high of 0.18 µg g(-1) (wet weight) in Scomberomorus sierra to a low of 0.009 µg g(-1) in Catostomidae. Average Hg levels were within published toxicity threshold values in forage fish for only two sites in Mexico (Puerto Vallarta and San Blas Estuary), and all were marine species, such as mackerel (Scomberomorus sierra), sea catfish (Ariopus spp.), and sardinas species (Centropomus spp.). Except for one sample from Nicaragua, sea catfish from Puerto Morazan, none of the fish from sites in Central America had Hg levels which exceeded the thresholds. Nonmetric multidimensional scaling revealed geographical differences in Hg levels with significant pairwise differences between sites along the Pacific Ocean (Mexico) versus the Bay of Campeche, partly due to differences in species composition of sampled fish (and species distributions). Hg increased with trophic level, as assessed by nitrogen stable isotope ratios (δ(15)N but not δ(13)C), in freshwater and marine, but not estuarine, environments. Hg concentrations in forage fish do not account for the elevated Hg reported for many osprey populations on the breeding grounds, thus primary sources of contamination appear to be in the north.

Evaluation of toxic effects of a diet containing fish contaminated with methylmercury in rats mimicking the exposure in the Amazon riverside population.

PubMed

Grotto, Denise; Valentini, Juliana; Serpeloni, Juliana Mara; Monteiro, Patrícia Alves Ponte; Latorraca, Elder Francisco; de Oliveira, Ricardo Santos; Antunes, Lusânia Maria Greggi; Garcia, Solange Cristina; Barbosa, Fernando

2011-11-01

This study was designed to evaluate the effects of a diet rich in fish contaminated with MeHg, mimicking the typical diet of the Amazon riverside population, in rats. Animals were randomly assigned to one of three groups with eight rats in each group: Group I-control, received commercial ration; Group II-received a diet rich in uncontaminated fish; Group III-received a diet rich in fish contaminated with MeHg. Treatment time was 12 weeks. Oxidative stress markers were evaluated, as well as the effects of this diet on DNA stability, systolic blood pressure (SBP), nitric oxide (NO) levels and histological damage in different tissues. There was a significant increase in SBP values in rats fed with MeHg-contaminated fish diet after the 10th week of the treatment. As far as oxidative stress biomarkers are concerned, no differences were observed in reduced glutathione and protein carbonyl levels, glutathione peroxidase, catalase, superoxide dismutase or δ-aminolevulinate dehydratase activities between the groups of animals receiving contaminated and uncontaminated fish diets. On the other hand, malondialdehyde levels increased significantly in rats fed with contaminated fish. NO levels were similar in all groups. DNA migration showed augmented in rats exposed to contaminated fish and histopathological analyses showed weak but significant leukocyte infiltration. Thus, we conclude that the MeHg-contaminated fish diet induced a slight lipid peroxidation and genotoxicity. However, these effects seem to be much less pronounced than when rats are exposed to aqueous solution containing CH3HgCl. Our findings support the contention that the chemical form of MeHg in fish or fish nutrients such as polyunsaturated fatty acids, Se or vitamin E could minimize the toxic effects of MeHg exposure in fish-eating communities. Copyright © 2011 Elsevier Inc. All rights reserved.

Quantifying the Human Impacts on Papua New Guinea Reef Fish Communities across Space and Time.

PubMed

Drew, Joshua A; Amatangelo, Kathryn L; Hufbauer, Ruth A

2015-01-01

Describing the drivers of species loss and of community change are important goals in both conservation and ecology. However, it is difficult to determine whether exploited species decline due to direct effects of harvesting or due to other environmental perturbations brought about by proximity to human populations. Here we quantify differences in species richness of coral reef fish communities along a human population gradient in Papua New Guinea to understand the relative impacts of fishing and environmental perturbation. Using data from published species lists we categorize the reef fishes as either fished or non-fished based on their body size and reports from the published literature. Species diversity for both fished and non-fished groups decreases as the size of the local human population increases, and this relationship is stronger in species that are fished. Additionally, comparison of modern and museum collections show that modern reef communities have proportionally fewer fished species relative to 19th century ones. Together these findings show that the reef fish communities of Papua New Guinea experience multiple anthropogenic stressors and that even at low human population levels targeted species experience population declines across both time and space.

Fish introductions in the former Soviet Union: The Sevan trout (Salmo ischchan) — 80 years later

PubMed Central

Bogdanowicz, Wiesław; Rutkowski, Robert; Gabrielyan, Bardukh K.; Ryspaev, Akylbek; Asatryan, Anzhela N.; Mkrtchyan, Jon A.; Bujalska, Barbara M.

2017-01-01

The Soviet Union played the leading role in fish introductions in Eurasia. However, only 3% of all introductions prior to 1978 gave a commercial benefit. One of the noteworthy examples appears to be the Sevan trout (Salmo ischchan Kessler, 1877)—an endemic salmonid of Lake Sevan in Armenia. This species has been introduced to Kirghizstan, Kazakhstan, and Uzbekistan, however, only the Kirghiz population has persisted in relatively high numbers. In this paper we provide the first extensive molecular study of S. ischchan using samples from the native population from Lake Sevan and three hatcheries in Armenia, as well as from the population introduced to Lake Issyk Kul in Kirghizstan. The Kirghiz population has been isolated since the introductions took place in 1930 and 1936. Our results, based on 11 nuclear microsatellites and a 905 bp fragment of the mitochondrial control region suggest that hatcheries have maintained genetic variability by way of ongoing translocations of individuals from Lake Sevan. Simultaneously, significant Garza-Williamson M-values suggest that bottlenecks could have reduced the genetic variability of the wild populations in the past. This hypothesis is supported by historical data, indicating highly manipulated water-level regulations and poaching as two main factors that dramatically impact fish abundance in the lake. On the other hand, a similar situation has been observed in Kirghizstan, but this population likely rebounded from small population size faster than the other populations examined. The Kirghiz population is significantly genetically differentiated from the other groups and have morphological features and biological attributes not observed in the source population. Genetic data imply that the effective population size in the native population is lower than that found in the introduced population, suggesting that some active protection of the Lake Sevan population may be needed urgently. PMID:28683097

Fish community changes in the St. Louis River estuary, Lake Superior, 1989-1996: Is it ruffe or population dynamics?

USGS Publications Warehouse

Bronte, Charles R.; Evrard, Lori M.; Brown, William P.; Mayo, Kathleen R.; Edwards, Andrew J.

1998-01-01

Ruffe (Gymnocephalus cernuus) have been implicated in density declines of native species through egg predation and competition for food in some European waters where they were introduced. Density estimates for ruffe and principal native fishes in the St. Louis River estuary (western Lake Superior) were developed for 1989 to 1996 to measure changes in the fish community in response to an unintentional introduction of ruffe. During the study, ruffe density increased and the densities of several native species decreased. The reductions of native stocks to the natural population dynamics of the same species from Chequamegon Bay, Lake Superior (an area with very few ruffe) were developed, where there was a 24-year record of density. Using these data, short- and long-term variations in catch and correlations among species within years were compared, and species-specific distributions were developed of observed trends in abundance of native fishes in Chequamegon Bay indexed by the slopes of densities across years. From these distributions and our observed trend-line slopes from the St. Louis River, probabilities of measuring negative change at the magnitude observed in the St. Louis River were estimated. Compared with trends in Chequamegon Bay, there was a high probability of obtaining the negative slopes measured for most species, which suggests natural population dynamics could explain, the declines rather than interactions with ruffe. Variable recruitment, which was not related to ruffe density, and associated density-dependent changes in mortality likely were responsible for density declines of native species.

Characterizing Fishing Effort and Spatial Extent of Coastal Fisheries

PubMed Central

Stewart, Kelly R.; Lewison, Rebecca L.; Dunn, Daniel C.; Bjorkland, Rhema H.; Kelez, Shaleyla; Halpin, Patrick N.; Crowder, Larry B.

2010-01-01

Biodiverse coastal zones are often areas of intense fishing pressure due to the high relative density of fishing capacity in these nearshore regions. Although overcapacity is one of the central challenges to fisheries sustainability in coastal zones, accurate estimates of fishing pressure in coastal zones are limited, hampering the assessment of the direct and collateral impacts (e.g., habitat degradation, bycatch) of fishing. We compiled a comprehensive database of fishing effort metrics and the corresponding spatial limits of fisheries and used a spatial analysis program (FEET) to map fishing effort density (measured as boat-meters per km2) in the coastal zones of six ocean regions. We also considered the utility of a number of socioeconomic variables as indicators of fishing pressure at the national level; fishing density increased as a function of population size and decreased as a function of coastline length. Our mapping exercise points to intra and interregional ‘hotspots’ of coastal fishing pressure. The significant and intuitive relationships we found between fishing density and population size and coastline length may help with coarse regional characterizations of fishing pressure. However, spatially-delimited fishing effort data are needed to accurately map fishing hotspots, i.e., areas of intense fishing activity. We suggest that estimates of fishing effort, not just target catch or yield, serve as a necessary measure of fishing activity, which is a key link to evaluating sustainability and environmental impacts of coastal fisheries. PMID:21206903

Characterizing fishing effort and spatial extent of coastal fisheries.

PubMed

Stewart, Kelly R; Lewison, Rebecca L; Dunn, Daniel C; Bjorkland, Rhema H; Kelez, Shaleyla; Halpin, Patrick N; Crowder, Larry B

2010-12-29

Biodiverse coastal zones are often areas of intense fishing pressure due to the high relative density of fishing capacity in these nearshore regions. Although overcapacity is one of the central challenges to fisheries sustainability in coastal zones, accurate estimates of fishing pressure in coastal zones are limited, hampering the assessment of the direct and collateral impacts (e.g., habitat degradation, bycatch) of fishing. We compiled a comprehensive database of fishing effort metrics and the corresponding spatial limits of fisheries and used a spatial analysis program (FEET) to map fishing effort density (measured as boat-meters per km²) in the coastal zones of six ocean regions. We also considered the utility of a number of socioeconomic variables as indicators of fishing pressure at the national level; fishing density increased as a function of population size and decreased as a function of coastline length. Our mapping exercise points to intra and interregional 'hotspots' of coastal fishing pressure. The significant and intuitive relationships we found between fishing density and population size and coastline length may help with coarse regional characterizations of fishing pressure. However, spatially-delimited fishing effort data are needed to accurately map fishing hotspots, i.e., areas of intense fishing activity. We suggest that estimates of fishing effort, not just target catch or yield, serve as a necessary measure of fishing activity, which is a key link to evaluating sustainability and environmental impacts of coastal fisheries.

MODELING THE RESPONSE OF FISH POPULATIONS TO EUTROPHICATION

EPA Science Inventory

Eutrophication resulting from nonpoint source pollution is one of the largest environmental problems in lakes and reservoirs around the world. Two characteristics of eutrophication, decreased dissolved oxygen and increased concentration of ammonia, are known to affect fishes, yet...

Fish with Chips: Tracking Reef Fish Movements to Evaluate Size and Connectivity of Caribbean Marine Protected Areas

PubMed Central

Pittman, Simon J.; Monaco, Mark E.; Friedlander, Alan M.; Legare, Bryan; Nemeth, Richard S.; Kendall, Matthew S.; Poti, Matthew; Clark, Randall D.; Wedding, Lisa M.; Caldow, Chris

2014-01-01

Coral reefs and associated fish populations have experienced rapid decline in the Caribbean region and marine protected areas (MPAs) have been widely implemented to address this decline. The performance of no-take MPAs (i.e., marine reserves) for protecting and rebuilding fish populations is influenced by the movement of animals within and across their boundaries. Very little is known about Caribbean reef fish movements creating a critical knowledge gap that can impede effective MPA design, performance and evaluation. Using miniature implanted acoustic transmitters and a fixed acoustic receiver array, we address three key questions: How far can reef fish move? Does connectivity exist between adjacent MPAs? Does existing MPA size match the spatial scale of reef fish movements? We show that many reef fishes are capable of traveling far greater distances and in shorter duration than was previously known. Across the Puerto Rican Shelf, more than half of our 163 tagged fish (18 species of 10 families) moved distances greater than 1 km with three fish moving more than 10 km in a single day and a quarter spending time outside of MPAs. We provide direct evidence of ecological connectivity across a network of MPAs, including estimated movements of more than 40 km connecting a nearshore MPA with a shelf-edge spawning aggregation. Most tagged fish showed high fidelity to MPAs, but also spent time outside MPAs, potentially contributing to spillover. Three-quarters of our fish were capable of traveling distances that would take them beyond the protection offered by at least 40–64% of the existing eastern Caribbean MPAs. We recommend that key species movement patterns be used to inform and evaluate MPA functionality and design, particularly size and shape. A re-scaling of our perception of Caribbean reef fish mobility and habitat use is imperative, with important implications for ecology and management effectiveness. PMID:24797815

Fish with chips: tracking reef fish movements to evaluate size and connectivity of Caribbean marine protected areas.

PubMed

Pittman, Simon J; Monaco, Mark E; Friedlander, Alan M; Legare, Bryan; Nemeth, Richard S; Kendall, Matthew S; Poti, Matthew; Clark, Randall D; Wedding, Lisa M; Caldow, Chris

2014-01-01

Coral reefs and associated fish populations have experienced rapid decline in the Caribbean region and marine protected areas (MPAs) have been widely implemented to address this decline. The performance of no-take MPAs (i.e., marine reserves) for protecting and rebuilding fish populations is influenced by the movement of animals within and across their boundaries. Very little is known about Caribbean reef fish movements creating a critical knowledge gap that can impede effective MPA design, performance and evaluation. Using miniature implanted acoustic transmitters and a fixed acoustic receiver array, we address three key questions: How far can reef fish move? Does connectivity exist between adjacent MPAs? Does existing MPA size match the spatial scale of reef fish movements? We show that many reef fishes are capable of traveling far greater distances and in shorter duration than was previously known. Across the Puerto Rican Shelf, more than half of our 163 tagged fish (18 species of 10 families) moved distances greater than 1 km with three fish moving more than 10 km in a single day and a quarter spending time outside of MPAs. We provide direct evidence of ecological connectivity across a network of MPAs, including estimated movements of more than 40 km connecting a nearshore MPA with a shelf-edge spawning aggregation. Most tagged fish showed high fidelity to MPAs, but also spent time outside MPAs, potentially contributing to spillover. Three-quarters of our fish were capable of traveling distances that would take them beyond the protection offered by at least 40-64% of the existing eastern Caribbean MPAs. We recommend that key species movement patterns be used to inform and evaluate MPA functionality and design, particularly size and shape. A re-scaling of our perception of Caribbean reef fish mobility and habitat use is imperative, with important implications for ecology and management effectiveness.

Importance of floodplain connectivity to fish populations in the Apalachicola River, Florida

USGS Publications Warehouse

Burgess, O.T.; Pine, William E.; Walsh, S.J.

2013-01-01

Floodplain habitats provide critical spawning and rearing habitats for many large-river fishes. The paradigm that floodplains are essential habitats is often a key reason for restoring altered rivers to natural flow regimes. However, few studies have documented spatial and temporal utilization of floodplain habitats by adult fish of sport or commercial management interest or assessed obligatory access to floodplain habitats for species' persistence. In this study, we applied telemetry techniques to examine adult fish movements between floodplain and mainstem habitats, paired with intensive light trap sampling of larval fish in these same habitats, to assess the relationships between riverine flows and fish movement and spawning patterns in restored and unmodified floodplain distributaries of the Apalachicola River, Florida. Our intent is to inform resource managers on the relationships between the timing, magnitude and duration of flow events and fish spawning as part of river management actions. Our results demonstrate spawning by all study species in floodplain and mainstem river habitat types, apparent migratory movements of some species between these habitats, and distinct spawning events for each study species on the basis of fish movement patterns and light trap catches. Additionally, Micropterus spp., Lepomis spp. and, to a lesser degree, Minytrema melanops used floodplain channel habitat that was experimentally reconnected to the mainstem within a few weeks of completing the restoration. This result is of interest to managers assessing restoration activities to reconnect these habitats as part of riverine restoration programmes globally.

Fish everywhere, all the time: modeling fish in the riverscape

EPA Science Inventory

From 2002-2006, EPA’s Western Ecology Division conducted innovative research on the population dynamics of fish within an entire stream network. Employing individual tagging and tracking technology, we examined spatial patterns of juvenile coho salmon (Oncorhynchus kisutch...

Relationships between bald eagle productivity and dynamics of fish populations and fisheries in the Wisconsin waters of Lake Superior, 1983-1999

USGS Publications Warehouse

Hoff, Michael H.; Meyer, Michael W.; Van Stappen, Julie; Fratt, Thomas W.

2004-01-01

Bald eagle (Haliaeetus leucocephalus) abundance declined in the 1950s and 1960s along the Wisconsin waters of Lake Superior, and were nearly absent along Wisconsin's Lake Superior shoreline. The population began to increase again between 1980 and 1983, and since then bald eagles nesting on islands along Wisconsin's Lake Superior shoreline (i.e., Apostle Islands) reproduced at a lower rate than have those nesting along the mainland shoreline of the lake and inland. Recent research indicated that bioaccumulation of toxic chemicals in the aquatic food chain no longer limits bald eagle reproduction there, and that productivity at island nests was lower than at mainland nests and inland nests as the result of low food availability. Management agencies have sought models that accurately predict productivity and explain ecological relationships, but no satisfactory models had previously been developed. Modeling was conducted here to determine which factors best explained productivity variability. The Ricker stock-recruitment model derived from only the bivariate breeding pair and productivity data explained only 1% of the variability in productivity data. The functional relationship that explained the greatest amount of productivity variation (83%) included the number of breeding pairs, burbot (Lota lota) biomass, longnose sucker (Catostomus catostomus) biomass, and commercial harvest of nontarget fishes. Model results were interpreted to mean that productivity was positively affected by populations of burbot and longnose sucker, which are important prey items, and by commercial fishermen feeding nontarget fish to bald eagles. Harvest of nontarget fishes by tribal fishermen and burbot and longnose sucker populations have not tended to change during the entire study period, although the burbot population has declined since 1991. Therefore, bald eagle productivity is not predicted to increase unless burbot, longnose sucker, or other preferred prey of bald eagles increases

Modeling tribal exposures to methyl mercury from fish consumption

EPA Science Inventory

Exposure assessment and risk management considerations for tribal fish consumption are different than for the general U.S. population because of higher fish intake from subsistence fishing and/or from unique cultural practices. This research summarizes analyses of available data ...

Strong population genetic structuring in an annual fish, Nothobranchius furzeri, suggests multiple savannah refugia in southern Mozambique.

PubMed

Bartáková, Veronika; Reichard, Martin; Janko, Karel; Polačik, Matej; Blažek, Radim; Reichwald, Kathrin; Cellerino, Alessandro; Bryja, Josef

2013-09-12

Intraspecific genetic variation of African fauna has been significantly affected by pronounced climatic fluctuations in Plio-Pleistocene, but, with the exception of large mammals, very limited empirical data on diversity of natural populations are available for savanna-dwelling animals. Nothobranchius furzeri is an annual fish from south-eastern Africa, inhabiting discrete temporary savannah pools outside main river alluvia. Their dispersal is limited and population processes affecting its genetic structure are likely a combination of those affecting terrestrial and aquatic taxa. N. furzeri is a model taxon in ageing research and several populations of known geographical origin are used in laboratory studies. Here, we analysed the genetic structure, diversity, historical demography and temporal patterns of divergence in natural populations of N. furzeri across its entire distribution range. Genetic structure and historical demography of N. furzeri were analysed using a combination of mitochondrial (partial cytochrome b sequences, 687 bp) and nuclear (13 microsatellites) markers in 693 fish from 36 populations. Genetic markers consistently demonstrated strong population structuring and suggested two main genetic groups associated with river basins. The split was dated to the Pliocene (>2 Mya). The northern group inhabits savannah pools across the basin of the intermittent river Chefu in south-western Mozambique and eastern Zimbabwe. The southern group (from southernmost Mozambique) is subdivided, with the River Limpopo forming a barrier (maximum divergence time 1 Mya). A strong habitat fragmentation (isolated temporary pools) is reflected in significant genetic structuring even between adjacent pools, with a major influence of genetic drift and significant isolation-by-distance. Analysis of historical demography revealed that the expansion of both groups is ongoing, supported by frequent founder effects in marginal parts of the range and evidence of secondary

Great lakes prey fish populations: a cross-basin overview of status and trends based on bottom trawl surveys, 1978-2012

USGS Publications Warehouse

Gorman, Owen T.

2012-01-01

The assessment of prey fish stocks in the Great Lakes have been conducted annually with bottom trawls since the 1970s by the Great Lakes Science Center, sometimes assisted by partner agencies. These stock assessments provide data on the status and trends of prey fish that are consumed by important commercial and recreational fishes. Although all these annual surveys are conducted using bottom trawls, they differ among the lakes in the proportion of the lake covered, seasonal timing, bottom trawl gear used, and the manner in which the trawl is towed (across or along bottom contours). Because each assessment is unique in one or more important aspects, direct comparison of prey fish catches among lakes is not straightforward. However, all of the assessments produce indices of abundance or biomass that can be standardized to facilitate comparisons of status and trends across all the Great Lakes. In this report, population indices were standardized to the highest value for a time series within each lake for the following principal prey species: cisco (Coregonus artedi), bloater (C. hoyi), rainbow smelt (Osmerus mordax), and alewife (Alosa pseudoharengus). Indices were also provided for round goby (Neogobius melanostomus), an invasive fish that has proliferated throughout the basin over the past 18 years. These standardized indices represent the best available long-term indices of relative abundance for these fishes across all of the Great Lakes. In this report, standardized indices are presented in graphical form along with synopses to provide a short, informal cross-basin summary of the status and trends of principal prey fishes. In keeping with this intent, tables, references, and a detailed discussion were omitted.

The role of fish in a globally changing food system

USGS Publications Warehouse

Lynch, Abigail J.; MacMillan, J. Randy

2017-01-01

Though humans have been fishing for food since they first created tools to hunt, modern food systems are predominately terrestrial focused and fish are frequently overlooked. Yet, within the global food system, fish play an important role in meeting current and future food needs. Capture fisheries are the last large-scale “wild” food, and aquaculture is the fastest growing food production sector in the world. Currently, capture fisheries and aquaculture provide 4.3 billion people with at least 15% of their animal protein. In addition to providing protein and calories, fish are important sources of critical vitamins and vital nutrients that are difficult to acquire through other food sources. As the climate changes, human populations will continue to grow, cultural tastes will evolve, and fish populations will respond. Sustainable fisheries and aquaculture are poised to fill demand for food not met by terrestrial food systems. Climate change and other global changes will increase, decrease, or modify many wild fish populations and aquaculture systems. Understanding the knowledge gaps around these implications for global change on fish production is critical. Applied research and adaptive management techniques can assist with the necessary evolution of sustainable food systems to include a stronger emphasis on fish and other aquatic organisms.

Methodological issues affecting the study of fish parasites. III. Effect of fish preservation method.

PubMed

Kvach, Yuriy; Ondračková, Markéta; Janáč, Michal; Jurajda, Pavel

2018-03-05

The aim of this study was to evaluate the influence of preservation method on the results of parasite community studies. Two host species, European perch Perca fluviatilis and European bitterling Rhodeus amarus, were examined for parasites after having been subjected to 4 different storage treatments: freezing, preservation in 4% formaldehyde or 70% ethanol and transportation of live (fresh) fish as a control. Preservation prior to dissection resulted in a loss of information, leading to incomplete quantitative data (all preservation treatments), qualitative data (ethanol and formaldehyde preservation) and a lowered ability to determine parasites to species level based on morphology compared to dissecting fresh fish. Of the more abundant taxa, only crustaceans and acanthocephalans provided relatively even results between treatments. We conclude that preservation media, such as ethanol or formaldehyde, significantly affects the ability to obtain precise parasite community data; hence, we recommend the use of freshly sacrificed fish for parasite community studies whenever possible. Alternatively, freezing may prove acceptable for evaluating parasite community taxonomic composition.

Effects of Fishing and Regional Species Pool on the Functional Diversity of Fish Communities

PubMed Central

Martins, Gustavo M.; Arenas, Francisco; Neto, Ana I.; Jenkins, Stuart R.

2012-01-01

The potential population and community level impacts of fishing have received considerable attention, but little is known about how fishing influences communities’ functional diversity at regional scales. We examined how estimates of functional diversity differed among 25 regions of variable richness and investigated the functional consequences of removing species targeted by commercial fisheries. Our study shows that fishing leads to substantial losses in functional diversity. The magnitude of such loss was, however, reduced in the more speciose regions. Moreover, the removal of commercially targeted species caused a much larger reduction in functional diversity than expected by random species deletions, which was a consequence of the selective nature of fishing for particular species traits. Results suggest that functional redundancy is spatially variable, that richer biotas provide some degree of insurance against the impact of fishing on communities’ functional diversity and that fishing predominantly selects for particular species traits. Understanding how fishing impacts community functional diversity is key to predict its effects for biodiversity as well as ecosystem functioning. PMID:22952950

Distribution and habitat use of the Missouri River and Lower Yellowstone River benthic fishes from 1996 to 1998: A baseline for fish community recovery

USGS Publications Warehouse

Wildhaber, M.L.; Gladish, D.W.; Arab, A.

2011-01-01

Past and present Missouri River management practices have resulted in native fishes being identified as in jeopardy. In 1995, the Missouri River Benthic Fishes Study was initiated to provide improved information on Missouri River fish populations and how alterations might affect them. The study produced a baseline against which to evaluate future changes in Missouri River operating criteria. The objective was to evaluate population structure and habitat use of benthic fishes along the entire mainstem Missouri River, exclusive of reservoirs. Here we use the data from this study to provide a recent-past baseline for on-going Missouri River fish population monitoring programmes along with a more powerful method for analysing data containing large percentages of zero values. This is carried out by describing the distribution and habitat use of 21 species of Missouri River benthic fishes based on catch-per-unit area data from multiple gears. We employ a Bayesian zero-inflated Poisson model expanded to include continuous measures of habitat quality (i.e. substrate composition, depth, velocity, temperature, turbidity and conductivity). Along with presenting the method, we provide a relatively complete picture of the Missouri River benthic fish community and the relationship between their relative population numbers and habitat conditions. We demonstrate that our single model provides all the information that is often obtained by a myriad of analytical techniques. An important advantage of the present approach is reliable inference for patterns of relative abundance using multiple gears without using gear efficiencies.

76 FR 56053 - 2011-2012 Refuge-Specific Hunting and Sport Fishing Regulations

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-09

...(j). We sometimes grant new shot types conditional approvals until we complete all necessary studies... adds one refuge to the list of areas open for hunting and/or sport fishing and increases the activities... specific management plans for each refuge prior to opening it to hunting or sport fishing. In many cases...

Grouping facilitates avoidance of parasites by fish

PubMed Central

2013-01-01

Background Parasite distribution is often highly heterogeneous, and intensity of infection depends, among other things, on how well hosts can avoid areas with a high concentration of parasites. We studied the role of fish behaviour in avoiding microhabitats with a high infection risk using Oncorhynchus mykiss and cercariae of Diplostomum pseudospathaceum as a model. Spatial distribution of parasites in experimental tanks was highly heterogeneous. We hypothesized that fish in groups are better at recognizing a parasitized area and avoiding it than solitary fish. Methods Number of fish, either solitary or in groups of 5, was recorded in different compartments of a shuttle tank where fish could make a choice between areas with different risk of being infected. Intensity of infection was assessed and compared with the number of fish recorded in the compartment with parasites and level of fish motility. Results Both solitary fish and fish in groups avoided parasitized areas, but fish in groups avoided it more strongly and thus acquired significantly fewer parasites than solitary fish. Prevalence of infection among grouped and solitary fish was 66 and 92 %, respectively, with the mean abundance two times higher in the solitary fish. Between-individual variation in the number of parasites per fish was higher in the “groups” treatment (across all individuals) than in the “solitary” treatment. Avoidance behaviour was more efficient when fish were allowed to explore the experimental arena prior to parasite exposure. High motility of fish was shown to increase the acquisition of D. pseudospathaceum. Conclusion Fish in groups better avoided parasitized habitat, and acquired significantly fewer parasites than solitary fish. We suggest that fish in groups benefit from information about parasites gained from other members of a group. Grouping behaviour may be an efficient mechanism of parasite avoidance, together with individual behaviour and immune responses of fishes

Grouping facilitates avoidance of parasites by fish.

PubMed

Mikheev, Victor N; Pasternak, Anna F; Taskinen, Jouni; Valtonen, Tellervo E

2013-10-17

Parasite distribution is often highly heterogeneous, and intensity of infection depends, among other things, on how well hosts can avoid areas with a high concentration of parasites. We studied the role of fish behaviour in avoiding microhabitats with a high infection risk using Oncorhynchus mykiss and cercariae of Diplostomum pseudospathaceum as a model. Spatial distribution of parasites in experimental tanks was highly heterogeneous. We hypothesized that fish in groups are better at recognizing a parasitized area and avoiding it than solitary fish. Number of fish, either solitary or in groups of 5, was recorded in different compartments of a shuttle tank where fish could make a choice between areas with different risk of being infected. Intensity of infection was assessed and compared with the number of fish recorded in the compartment with parasites and level of fish motility. Both solitary fish and fish in groups avoided parasitized areas, but fish in groups avoided it more strongly and thus acquired significantly fewer parasites than solitary fish. Prevalence of infection among grouped and solitary fish was 66 and 92 %, respectively, with the mean abundance two times higher in the solitary fish. Between-individual variation in the number of parasites per fish was higher in the "groups" treatment (across all individuals) than in the "solitary" treatment. Avoidance behaviour was more efficient when fish were allowed to explore the experimental arena prior to parasite exposure. High motility of fish was shown to increase the acquisition of D. pseudospathaceum. Fish in groups better avoided parasitized habitat, and acquired significantly fewer parasites than solitary fish. We suggest that fish in groups benefit from information about parasites gained from other members of a group. Grouping behaviour may be an efficient mechanism of parasite avoidance, together with individual behaviour and immune responses of fishes. Avoidance of habitats with a high parasite risk

Determination of a site-specific reference dose for methylmercury for fish-eating populations.

PubMed

Shipp, A M; Gentry, P R; Lawrence, G; Van Landingham, C; Covington, T; Clewell, H J; Gribben, K; Crump, K

2000-11-01

methylmercury, the exposures of concern for the Point Comfort site are from the chronic consumption of relatively low concentrations of methylmercury in fish. Since the publication of the USEPA RfD, several analyses of chronic exposure to methylmercury in fish-eating populations have been reported. The purpose of the analysis reported here was to evaluate the possibility of deriving an RfD for methylmercury, specifically for the case of fish ingestion, on the basis of these new studies. In order to better support the risk-management decisions associated with developing a remediation approach for the site in question, the analysis was designed to provide information on the distribution of acceptable ingestion rates across a population, which could reasonably be expected to be consistent with the results of the epidemiological studies of other fish-eating populations. Based on a review of the available literature on the effects of methylmercury, a study conducted with a population in the Seychelles Islands was selected as the critical study for this analysis. The exposures to methylmercury in this population result from chronic, multigenerational ingestion of contaminated fish. This prospective study was carefully conducted and analyzed, included a large cohort of mother-infant pairs, and was relatively free of confounding factors. The results of this study are essentially negative, and a no-observed-adverse-effect level (NOAEL) derived from the estimated exposures has recently been used by the Agency for Toxic Substances and Disease Registry (ATSDR) as the basis for a chronic oral minimal risk level (MRL) for methylmercury. In spite of the fact that no statistically significant effects were observed in this study, the data as reported are suitable for dose-response analysis using the BMD method. Evaluation of the BMD method used in this analysis, as well as in the current USEPA RfD, has demonstrated that the resulting 95% lower bound on the 10% benchmark dose (BMDL) represents a

Larvivorous fish for preventing malaria transmission.

PubMed

Walshe, Deirdre P; Garner, Paul; Abdel-Hameed Adeel, Ahmed A; Pyke, Graham H; Burkot, Tom

2013-12-10

population. In the absence of direct evidence of an effect on transmission, we carried out a secondary analysis on studies that evaluated the effect of introducing larvivorous fish on the density or presence of immature anopheline mosquitoes (larvae and pupae forms) in community water sources to determine whether this intervention has any potential in further research on control of malaria vectors. Three review authors screened abstracts and examined potentially relevant studies by using an eligibility form. Two review authors independently extracted data and assessed risk of bias of included studies. If relevant data were unclear or were not reported, we wrote to the trial authors for clarification. We presented data in tables, and we summarized studies that evaluated the effects of fish introduction on anopheline immature density or presence, or both. We used GRADE to summarize evidence quality. We also examined whether the authors of included studies reported on any possible adverse impact of larvivorous fish introduction on non-target native species. We found no reliable studies that reported the effects of introducing larvivorous fish on malaria infection in nearby communities, on entomological inoculation rate, or on adult Anopheles density.For the secondary analysis, we examined the effects of introducing larvivorous fish on the density and presence of anopheline larvae and pupae in community water sources. We included 12 small studies, with follow-up from 22 days to five years. Studies were conducted in a variety of settings, including localized water bodies (such as wells, domestic water containers, fishponds, and pools; six studies), riverbed pools below dams (two studies), rice field plots (three studies), and water canals (two studies). All studies were at high risk of bias.The research was insufficient to determine whether larvivorous fish reduce the density of Anopheles larvae and pupae (nine studies, unpooled data, very low quality evidence). Some studies with

Food protein-induced enterocolitis syndrome caused by fish and/or shellfish in Italy.

PubMed

Miceli Sopo, Stefano; Monaco, Serena; Badina, Laura; Barni, Simona; Longo, Giorgio; Novembre, Elio; Viola, Serena; Monti, Giovanna

2015-12-01

The study describes the demographic features, culprit foods, clinical features and outcomes for children presenting with acute fish and/or shellfish food protein-induced enterocolitis syndrome (FPIES) in four Italian paediatric allergy centres. A retrospective/prospective study was undertaken. All children diagnosed with fish or shellfish FPIES were enrolled. The diagnosis of FPIES was based on Sicherer's or Miceli Sopo clinical criteria. Skin prick tests (SPT) were performed in all patients, at the time of diagnosis and prior to OFC. Seventy children were enrolled. Mean age at first episode was 14 months (range 6-46 months); mean age at diagnosis was 34 months (range 6-164 months). Sole and cod were the fish most commonly implicated. Fifty-seven of 70 (81%) children had FPIES exclusively to fish, 37 of 57 (65%) children had single-fish FPIES, 20 of 57 (35%) multiple-fish FPIES, nine of 70 (13%) presented adverse reactions exclusively to shellfish, and four of 70 (6%) presented adverse reactions to both fish and shellfish. Only four (5.7%) children presented episodes of acute FPIES with different foods (2 to cow's milk, 1 to egg, 1 to beef); in all cases, onset was prior to that of fish or shellfish FPIES. Fifteen of 70 (21%) children tolerated fish other than the offending fish. Twenty-four of 70 (34%) children achieved tolerance (age range 24-102 months). The chief peculiarities of acute fish and shellfish FPIES, compared to more frequent cow's milk or soy FPIES, are (i) later age of onset, (ii) longer persistence and (iii) possibility of tolerating fish other than the offending fish. Adverse reactions with shellfish are possible. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Current ecological understanding of fungal-like pathogens of fish: what lies beneath?

PubMed Central

Gozlan, Rodolphe E.; Marshall, Wyth L.; Lilje, Osu; Jessop, Casey N.; Gleason, Frank H.; Andreou, Demetra

2014-01-01

Despite increasingly sophisticated microbiological techniques, and long after the first discovery of microbes, basic knowledge is still lacking to fully appreciate the ecological importance of microbial parasites in fish. This is likely due to the nature of their habitats as many species of fish suffer from living beneath turbid water away from easy recording. However, fishes represent key ecosystem services for millions of people around the world and the absence of a functional ecological understanding of viruses, prokaryotes, and small eukaryotes in the maintenance of fish populations and of their diversity represents an inherent barrier to aquatic conservation and food security. Among recent emerging infectious diseases responsible for severe population declines in plant and animal taxa, fungal and fungal-like microbes have emerged as significant contributors. Here, we review the current knowledge gaps of fungal and fungal-like parasites and pathogens in fish and put them into an ecological perspective with direct implications for the monitoring of fungal fish pathogens in the wild, their phylogeography as well as their associated ecological impact on fish populations. With increasing fish movement around the world for farming, releases into the wild for sport fishing and human-driven habitat changes, it is expected, along with improved environmental monitoring of fungal and fungal-like infections, that the full extent of the impact of these pathogens on wild fish populations will soon emerge as a major threat to freshwater biodiversity. PMID:24600442

Assessing power of large river fish monitoring programs to detect population changes: the Missouri River sturgeon example

USGS Publications Warehouse

Wildhaber, M.L.; Holan, S.H.; Bryan, J.L.; Gladish, D.W.; Ellersieck, M.

2011-01-01

In 2003, the US Army Corps of Engineers initiated the Pallid Sturgeon Population Assessment Program (PSPAP) to monitor pallid sturgeon and the fish community of the Missouri River. The power analysis of PSPAP presented here was conducted to guide sampling design and effort decisions. The PSPAP sampling design has a nested structure with multiple gear subsamples within a river bend. Power analyses were based on a normal linear mixed model, using a mixed cell means approach, with variance estimates from the original data. It was found that, at current effort levels, at least 20 years for pallid and 10 years for shovelnose sturgeon is needed to detect a 5% annual decline. Modified bootstrap simulations suggest power estimates from the original data are conservative due to excessive zero fish counts. In general, the approach presented is applicable to a wide array of animal monitoring programs.

Use of population viability analysis to evaluate CITES trade-management options for threatened marine fishes.

PubMed

Curtis, Janelle M R; Vincent, Amanda C J

2008-10-01

Achieving multiple conservation objectives can be challenging, particularly under high uncertainty. Having agreed to limit seahorse (Hippocampus) exports to sustainable levels, signatories to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) were offered the option of a single 10-cm minimum size limit (MSL) as an interim management measure for all Hippocampus species (> or =34). Although diverse stakeholders supported the recommended MSL, its biological and socioeconomic implications were not assessed quantitatively. We combined population viability analysis, model sensitivity analysis, and economic information to evaluate the trade-off between conservation threat to and long-term cumulative income from these exploited marine fishes of high conservation concern. We used the European long-snouted seahorse (Hippocampus guttulatus) as a representative species to compare the performance of MSLs set at alternative biological reference points. Our sensitivity analyses showed that in most of our scenarios, setting the MSL just above size at maturity (9.7 cm in H. guttulatus) would not prevent exploited populations from becoming listed as vulnerable. By contrast, the relative risk of decline and extinction were almost halved--at a cost of only a 5.6% reduction in long-term catches--by increasing the MSL to the size reached after at least one full reproductive season. On the basis of our analysis, a precautionary increase in the MSL could be compatible with sustaining fishers' livelihoods and international trade. Such management tactics that aid species conservation and have minimal effects on long term catch trends may help bolster the case for CITES trade management of other valuable marine fishes.

Genetic Evidence for Multiple Sources of the Non-Native Fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in Southern Florida

PubMed Central

Harrison, Elizabeth; Trexler, Joel C.; Collins, Timothy M.; Vazquez-Domínguez, Ella; Razo-Mendivil, Ulises; Matamoros, Wilfredo A.; Barrientos, Christian

2014-01-01

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7–8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions. PMID:25184569

Genetic evidence for multiple sources of the non-native fish Cichlasoma urophthalmus (Günther; Mayan Cichlids) in southern Florida.

PubMed

Harrison, Elizabeth; Trexler, Joel C; Collins, Timothy M; Vazquez-Domínguez, Ella; Razo-Mendivil, Ulises; Matamoros, Wilfredo A; Barrientos, Christian

2014-01-01

The number and diversity of source populations may influence the genetic diversity of newly introduced populations and affect the likelihood of their establishment and spread. We used the cytochrome b mitochondrial gene and nuclear microsatellite loci to identify the sources of a successful invader in southern Florida, USA, Cichlasoma urophthalmus (Mayan cichlid). Our cytochrome b data supported an introduction from Guatemala, while our microsatellite data suggested movement of Mayan Cichlids from the upper Yucatán Peninsula to Guatemala and introductions from Guatemala and Belize to Florida. The mismatch between mitochondrial and nuclear genomes suggests admixture of a female lineage from Guatemala, where all individuals were fixed for the mitochondrial haplotype found in the introduced population, and a more diverse but also relatively small number of individuals from Belize. The Florida cytochrome b haplotype appears to be absent from Belize (0 out of 136 fish screened from Belize had this haplotype). Genetic structure within the Florida population was minimal, indicating a panmictic population, while Mexican and Central American samples displayed more genetic subdivision. Individuals from the Upper Yucatán Peninsula and the Petén region of Guatemala were more genetically similar to each other than to fish from nearby sites and movement of Mayan Cichlids between these regions occurred thousands of generations ago, suggestive of pre-Columbian human transportation of Mayan Cichlids through this region. Mayan Cichlids present a rare example of cytonuclear disequilibrium and reduced genetic diversity in the introduced population that persists more than 30 years (at least 7-8 generations) after introduction. We suggest that hybridization occurred in ornamental fish farms in Florida and may contribute their establishment in the novel habitat. Hybridization prior to release may contribute to other successful invasions.

Larvivorous fish for preventing malaria transmission

PubMed Central

Walshe, Deirdre P; Garner, Paul; Adeel, Ahmed A; Pyke, Graham H; Burkot, Thomas R

2017-01-01

reported on malaria in the community or the density of the adult anopheline population. In the absence of direct evidence of an effect on transmission, we performed a secondary analysis on studies that evaluated the effect of introducing larvivorous fish on the density or presence of immature anopheline mosquitoes (larvae and pupae forms) in water sources to determine whether this intervention has any potential that may justify further research in the control of malaria vectors. Data collection and analysis Two review authors independently screened each article by title and abstract, and examined potentially relevant studies for inclusion using an eligibility form. At least two review authors independently extracted data and assessed risk of bias of included studies. If relevant data were unclear or were not reported, we contacted the study authors for clarification. We presented data in tables, and we summarized studies that evaluated the effects of introducing fish on anopheline immature density or presence, or both. We used the GRADE approach to summarize the certainty of the evidence. We also examined whether the included studies reported any possible adverse impact of introducing larvivorous fish on non-target native species. Main results We identified no studies that reported the effects of introducing larvivorous fish on the primary outcomes of this review: malaria infection in nearby communities, entomological inoculation rate, or on adult Anopheles density. For the secondary analysis, we examined the effects of introducing larvivorous fish on the density and presence of anopheline larvae and pupae in community water sources, and found 15 small studies with a follow-up period between 22 days and five years. These studies were undertaken in Sri Lanka (two studies), India (three studies), Ethiopia (one study), Kenya (two studies), Sudan (one study), Grande Comore Island (one study), Korea (two studies), Indonesia (one study), and Tajikistan (two studies). These

Monitoring fish distributions along electrofishing segments

USGS Publications Warehouse

Miranda, Leandro E.

2014-01-01

Electrofishing is widely used to monitor fish species composition and relative abundance in streams and lakes. According to standard protocols, multiple segments are selected in a body of water to monitor population relative abundance as the ratio of total catch to total sampling effort. The standard protocol provides an assessment of fish distribution at a macrohabitat scale among segments, but not within segments. An ancillary protocol was developed for assessing fish distribution at a finer scale within electrofishing segments. The ancillary protocol was used to estimate spacing, dispersion, and association of two species along shore segments in two local reservoirs. The added information provided by the ancillary protocol may be useful for assessing fish distribution relative to fish of the same species, to fish of different species, and to environmental or habitat characteristics.

The skin of fish as a transport epithelium: a review.

PubMed

Glover, Chris N; Bucking, Carol; Wood, Chris M

2013-10-01

The primary function of fish skin is to act as a barrier. It provides protection against physical damage and assists with the maintenance of homoeostasis by minimising exchange between the animal and the environment. However in some fish, the skin may play a more active physiological role. This is particularly true in species that inhabit specialised environmental niches (e.g. amphibious and air-breathing fish such as the lungfish), those with physiological characteristics that may subvert the need for the integument as a barrier (e.g. the osmoconforming hagfish), and/or fish with anatomical modifications of the epidermis (e.g. reduced epithelial thickness). Using examples from different fish groups (e.g. hagfishes, elasmobranchs and teleosts), the importance of fish skin as a transport epithelium for gases, ions, nitrogenous waste products, and nutrients was reviewed. The role of the skin in larval fish was also examined, with early life stages often utilising the skin as a surrogate gill, prior to the development of a functional branchial epithelium.

Standardizing the microbiota of fish used in research.

PubMed

Vatsos, I N

2017-08-01

Little attention has been paid to the effects of fish microbiotas on the reproducibility and comparability of fish studies so far. Extrinsic and intrinsic factors, such as water quality, environmental microbial populations, diet, host genetic profile, gender, age and stress status, affect fish microbiotas and create significant inter- and intra-species variations. Fish microbiotas play critical roles in many key aspects of host physiology, such as protection against pathogens, digestion and development of the digestive tract and the local immune system. Thus, greater effort should be invested in standardizing the microbiological profiles of research fish. In this context, issues requiring consideration include the establishment of isogenic and isobiotic fish lines, the standardization of rearing conditions and the development of appropriate tests to adequately describe microbial populations. There are many challenges involved in each of these issues, and the research community must decide which aspects should be standardized for each species and each type of research. For all studies in which microbiota is expected to exert an influence, thorough reporting is of paramount importance. Every step towards standardization increases study quality and simultaneously contributes to reducing the number of fish used in research, which is a legal and ethical obligation.

Lake Michigan: Man's effects on native fish stocks and other biota

USGS Publications Warehouse

Wells, LaRue; McLain, Alberton L.

1973-01-01

Exploitation was largely responsible for the changes in Lake Michigan fish stocks before the invasion of the smelt, and probably before the invasion of the sea lamprey. The lamprey and alewife, however, have exerted a greater impact than the fishery on native fish populations in recent decades. Accelerated eutrophication and other pollution, although important, have not equalled the other factors in causing changes in native fish populations.

Biotechnology applied to fish reproduction: tools for conservation.

PubMed

de Siqueira-Silva, Diógenes Henrique; Saito, Taiju; Dos Santos-Silva, Amanda Pereira; da Silva Costa, Raphael; Psenicka, Martin; Yasui, George Shigueki

2018-04-29

This review discusses the new biotechnological tools that are arising and promising for conservation and enhancement of fish production, mainly regarding the endangered and the most economically important species. Two main techniques, in particular, are available to avoid extinction of endangered fish species and to improve the production of commercial species. Germ cell transplantation technology includes a number of approaches that have been studied, such as the transplantation of embryo-to-embryo blastomere, embryo-to-embryo differentiated PGC, larvae to larvae and embryo differentiated PGC, transplantation of spermatogonia from adult to larvae or between adults, and oogonia transplantation. However, the success of germ cell transplantation relies on the prior sterilization of fish, which can be performed at different stages of fish species development by means of several protocols that have been tested in order to achieve the best approach to produce a sterile fish. Among them, fish hybridization and triploidization, germline gene knockdown, hyperthermia, and chemical treatment deserve attention based on important results achieved thus far. This review currently used technologies and knowledge about surrogate technology and fish sterilization, discussing the stronger and the weaker points of each approach.

Accumulation by fish of contaminants released from dredged sediments

USGS Publications Warehouse

Seelye, James G.; Hesselberg, Robert J.; Mac, Michael J.

1982-01-01

Inasmuch as the process of dredging and disposing of dredged materials causes a resuspension of these materials and an increase in bioavailability of associated contaminants, we conducted a series of experiments to examine the potential accumulation by fish of contaminants from suspended sediments. In the first experiment we compared accumulation of contaminants by yellow perch of hatchery and lake origin and found that after 10 days of exposure to nonaerated sediments, fish of hatchery origin accumulated PCBs and Fe, while fish of lake origin accumulated As, Cr, Fe, and Na. Two additional exposures were conducted to evaluate the effects of aerating the sediments prior to measuring bioavailability of associated contaminants. Fish of hatchery origin exposed to nonaerated sediments for 10 days accumulated PCBs and Hg, while fish of hatchery origin exposed to aerated sediments for 10 days accumulated PCBs, DDE, Zn, Fe, Cs, and Se. These results demonstrated not only the potential for uptake of contaminants by fish as a result of dredging but also the potential utility of fish bioassays in evaluating proposed dredging operations.

Estimating the impact of oyster restoration scenarios on transient fish production

USGS Publications Warehouse

McCoy, Elizabeth; Borrett, Stuart R.; LaPeyre, Megan K.; Peterson, Bradley J.

2017-01-01

Oyster reef restoration projects are increasing in number both to enhance oyster density and to retain valuable ecosystem services provided by oyster reefs. Although some oyster restoration projects have demonstrated success by increasing density and biomass of transient fish, it still remains a challenge to quantify the effects of oyster restoration on transient fish communities. We developed a bioenergetics model to assess the impact of selected oyster reef restoration scenarios on associated transient fish species. We used the model to analyze the impact of changes in (1) oyster population carrying capacity; (2) oyster population growth rate; and (3) diet preference of transient fish on oyster reef development and associated transient fish species. Our model results indicate that resident fish biomass is directly affected by oyster restoration and oyster biomass, and oyster restoration can have cascading impacts on transient fish biomass. Furthermore, the results highlight the importance of a favorable oyster population growth rate during early restoration years, as it can lead to rapid increases in mean oyster biomass and biomass of transient fish species. The model also revealed that a transient fish's diet solely dependent on oyster reef-derived prey could limit the biomass of transient fish species, emphasizing the importance of habitat connectivity in estuarine areas to enhance transient fish species biomass. Simple bioenergetics models can be developed to understand the dynamics of a system and make qualitative predictions of management and restoration scenarios.

Estimating fish consumption and targeting high risk consumer populations in NJ and NY

EPA Science Inventory

An estimated 16.4% of US females of reproductive age (15 to 45 years) eat fish at least once per day. While fish is a good source of protein, with some species high in the omega-3 fatty acids that are associated with cardiovascular health, studies also indicate some fish and she...

Invasive Cyprinid Fish in Europe Originate from the Single Introduction of an Admixed Source Population Followed by a Complex Pattern of Spread

PubMed Central

Simon, Andrea; Britton, Robert; Gozlan, Rodolphe; van Oosterhout, Cock; Volckaert, Filip A. M.; Hänfling, Bernd

2011-01-01

The Asian cyprinid fish, the topmouth gudgeon (Pseudorasbora parva), was introduced into Europe in the 1960s. A highly invasive freshwater fish, it is currently found in at least 32 countries outside its native range. Here we analyse a 700 base pair fragment of the mitochondrial cytochrome b gene to examine different models of colonisation and spread within the invasive range, and to investigate the factors that may have contributed to their invasion success. Haplotype and nucleotide diversity of the introduced populations from continental Europe was higher than that of the native populations, although two recently introduced populations from the British Isles showed low levels of variability. Based on coalescent theory, all introduced and some native populations showed a relative excess of nucleotide diversity compared to haplotype diversity. This suggests that these populations are not in mutation-drift equilibrium, but rather that the relative inflated level of nucleotide diversity is consistent with recent admixture. This study elucidates the colonisation patterns of P. parva in Europe and provides an evolutionary framework of their invasion. It supports the hypothesis that their European colonisation was initiated by their introduction to a single location or small geographic area with subsequent complex pattern of spread including both long distance and stepping-stone dispersal. Furthermore, it was preceded by, or associated with, the admixture of genetically diverse source populations that may have augmented its invasive-potential. PMID:21674031

[Overview of the artificial enhancement and release of endemic freshwater fish in China].

PubMed

Yang, Jun-Xing; Pan, Xiao-Fu; Chen, Xiao-Yong; Wang, Xiao-Ai; Zhao, Ya-Peng; Li, Jian-You; Li, Zai-Yun

2013-08-01

Due to declining fishery resources and the growing development of conservation aquaculture, artificial freshwater fish enhancement and releasing have begun to replace traditional means of recovering endemic and rare fish populations. Artificial proliferation can be beneficial both to endemic fish conservation and technical bottleneck breakthroughs. This overview presents a review of the latest research and the underlying principles behind the conservation implementation processes, as well as the research status of artificial enhancement and release of endangered freshwater fish species in China, such as Mylopharyngodon piceus, Ctenopharyngodon idellus, Hypophthalmichthys molitrix, H. nobilis, Acipenser sinensis, Myxocyprinus asiaticus, and Sinocyclocheilus grahami. The overview also presents evolutionarily significant units, sperm and egg quality, and cryopreservation technologies and cell cultures used in artificial enhancement and release, which help standardize genetic management and minimize the genetic differences between hatched and wild populations. Monitoring fish from cultivation to release is essential to evaluating wild population recovery and adjusting recovery plans. Moreover, the remaining problems of artificial releases are discussed in-depth, touching on issues such as the limitations of domestic hatching, the base number of wild populations necessary to the environment, the proper size at which to release juveniles' into the environment, the geographic confusion of populations, the contradictions in commercial fish selection and fish conservation, and "exotic species" invasion.

Comparison of sampling methodologies and estimation of population parameters for a temporary fish ectoparasite.

PubMed

Artim, J M; Sikkel, P C

2016-08-01

Characterizing spatio-temporal variation in the density of organisms in a community is a crucial part of ecological study. However, doing so for small, motile, cryptic species presents multiple challenges, especially where multiple life history stages are involved. Gnathiid isopods are ecologically important marine ectoparasites, micropredators that live in substrate for most of their lives, emerging only once during each juvenile stage to feed on fish blood. Many gnathiid species are nocturnal and most have distinct substrate preferences. Studies of gnathiid use of habitat, exploitation of hosts, and population dynamics have used various trap designs to estimate rates of gnathiid emergence, study sensory ecology, and identify host susceptibility. In the studies reported here, we compare and contrast the performance of emergence, fish-baited and light trap designs, outline the key features of these traps, and determine some life cycle parameters derived from trap counts for the Eastern Caribbean coral-reef gnathiid, Gnathia marleyi. We also used counts from large emergence traps and light traps to estimate additional life cycle parameters, emergence rates, and total gnathiid density on substrate, and to calibrate the light trap design to provide estimates of rate of emergence and total gnathiid density in habitat not amenable to emergence trap deployment.

Projected risk of population declines for native fish species in the Upper Mississippi River

USGS Publications Warehouse

Crimmins, S.M.; Boma, P.; Thogmartin, W.E.

2015-01-01

Conservationists are in need of objective metrics for prioritizing the management of habitats. For individual species, the threat of extinction is often used to prioritize what species are in need of conservation action. Using long-term monitoring data, we applied a Bayesian diffusion approximation to estimate quasi-extinction risk for 54 native fish species within six commercial navigation reaches along a 1350-km gradient of the upper Mississippi River system. We found a strong negative linear relationship between quasi-extinction risk and distance upstream. For some species, quasi-extinction estimates ranged from nearly zero in some reaches to one in others, suggesting substantial variability in threats facing individual river reaches. We found no evidence that species traits affected quasi-extinction risk across the entire system. Our results indicate that fishes within the upper Mississippi River system face localized threats that vary across river impact gradients. This suggests that conservation actions should be focused on local habitat scales but should also consider the additive effects on downstream conditions. We also emphasize the need for identification of proximate mechanisms behind observed and predicted population declines, as conservation actions will require mitigation of such mechanisms. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Organotin intake through fish consumption in Finland

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

Airaksinen, Riikka, E-mail: Riikka.Airaksinen@thl.fi; Rantakokko, Panu; Turunen, Anu W.

Background: Organotin compounds (OTCs) are a large class of synthetic chemicals with widely varying properties. Due to their potential adverse health effects, their use has been restricted in many countries. Humans are exposed to OTCs mostly through fish consumption. Objectives: The aim of this study was to describe OTC exposure through fish consumption and to assess the associated potential health risks in a Finnish population. Methods: An extensive sampling of Finnish domestic fish was carried out in the Baltic Sea and freshwater areas in 2005-2007. In addition, samples of imported seafood were collected in 2008. The chemical analysis was performedmore » in an accredited testing laboratory during 2005-2008. Average daily intake of the sum of dibutyltin (DBT), tributyltin (TBT), triphenyltin (TPhT) and dioctyltin (DOT) ({Sigma}OTCs) for the Finnish population was calculated on the basis of the measured concentrations and fish consumption rates. Results: The average daily intake of {Sigma}OTCs through fish consumption was 3.2 ng/kg bw day{sup -1}, which is 1.3% from the Tolerable Daily Intake (TDI) of 250 ng/kg bw day{sup -1} set by the European Food Safety Authority. In total, domestic wild fish accounted for 61% of the {Sigma}OTC intake, while the intake through domestic farmed fish was 4.0% and the intake through imported fish was 35%. The most important species were domestic perch and imported salmon and rainbow trout. Conclusions: The Finnish consumers are not likely to exceed the threshold level for adverse health effects due to OTC intake through fish consumption.« less

Overview on the effects of parasites on fish health

USGS Publications Warehouse

Iwanowicz, D.D.; Cipriano, R.C.; Bruckner, A.W.; Shchelkunov, I.S.

2011-01-01

It is believed by many that parasites are only as important as the fish they infect. Parasites are ubiquitous, primarily surviving in a dynamic equilibrium with their host(s) and they are often overlooked in fish health assessments. Changes in the environment, both anthropogenic and environmental, can alter the parasite/host equilibrium and cause disease or mortality in fish. Therefore it is imperative that we have knowledge of both parasites and parasitic communities within a given population. When fish kills occur, it can often be associated with changes in parasite density and community composition. Often the damage associated with these fish is relative to the rate of infestation with the parasite; a fish that is lightly infected will show few signs of the parasite, while a heavily infected fish may become physiologically impaired and even die. Parasites can cause mechanical damage (fusion of gill lamellae, tissue replacement), physiological damage (cell proliferation, immunomodulation, detrimental behavioral responses, altered growth) and reproductive damage. As parasitism is the most common lifestyle on the planet, understanding its role in the environment may help researchers understand changes in a given fish population or stream ecosystem.

Coral reef fishes exhibit beneficial phenotypes inside marine protected areas

PubMed Central

Carroll, Jessica; Rynerson, Kristen W.; Matthews, Danielle F.; Turingan, Ralph G.

2018-01-01

Human fishing effort is size-selective, preferentially removing the largest individuals from harvested stocks. Intensive, size-specific fishing mortality induces directional shifts in phenotypic frequencies towards the predominance of smaller and earlier-maturing individuals, which are among the primary causes of declining fish biomass. Fish that reproduce at smaller size and younger age produce fewer, smaller, and less viable larvae, severely reducing the reproductive capacity of harvested populations. Marine protected areas (MPAs) are extensively utilized in coral reefs for fisheries management, and are thought to mitigate the impacts of size-selective fishing mortality and supplement fished stocks through larval export. However, empirical evidence of disparities in fitness-relevant phenotypes between MPAs and adjacent fished reefs is necessary to validate this assertion. Here, we compare key life-history traits in three coral-reef fishes (Acanthurus nigrofuscus, Ctenochaetus striatus, and Parupeneus multifasciatus) between MPAs and fished reefs in the Philippines. Results of our analyses support previous hypotheses regarding the impacts of MPAs on phenotypic traits. Asymptotic length (Linf) and growth rates (K) differed between conspecifics in MPAs and fished reefs, with protected populations exhibiting phenotypes that are known to confer higher fecundity. Additionally, populations demonstrated increases in length at 50% maturity (L50) inside MPAs compared to adjacent areas, although age at 50% maturity (A50) did not appear to be impacted by MPA establishment. Shifts toward advantageous phenotypes were most common in the oldest and largest MPAs, but occurred in all of the MPAs examined. These results suggest that MPAs may provide protection against the impacts of size-selective harvest on life-history traits in coral-reef fishes. PMID:29470525

SIMULATING FISH ASSEMBLAGE DYNAMICS IN RIVER NETWORKS

EPA Science Inventory

My recently retired colleague, Joan Baker, and I have developed a prototype computer simulation model for studying the effects of human and non-human alterations of habitats and species availability on fish assemblage populations. The fish assemblage model, written in R, is a sp...

Drought survival is a threshold function of habitat size and population density in a fish metapopulation.

PubMed

White, Richard S A; McHugh, Peter A; McIntosh, Angus R

2016-10-01

Because smaller habitats dry more frequently and severely during droughts, habitat size is likely a key driver of survival in populations during climate change and associated increased extreme drought frequency. Here, we show that survival in populations during droughts is a threshold function of habitat size driven by an interaction with population density in metapopulations of the forest pool dwelling fish, Neochanna apoda. A mark-recapture study involving 830 N. apoda individuals during a one-in-seventy-year extreme drought revealed that survival during droughts was high for populations occupying pools deeper than 139 mm, but declined steeply in shallower pools. This threshold was caused by an interaction between increasing population density and drought magnitude associated with decreasing habitat size, which acted synergistically to increase physiological stress and mortality. This confirmed two long-held hypotheses, firstly concerning the interactive role of population density and physiological stress, herein driven by habitat size, and secondly, the occurrence of drought survival thresholds. Our results demonstrate how survival in populations during droughts will depend strongly on habitat size and highlight that minimum habitat size thresholds will likely be required to maximize survival as the frequency and intensity of droughts are projected to increase as a result of global climate change. © 2016 John Wiley & Sons Ltd.

Habitat degradation and fishing effects on the size structure of coral reef fish communities.

PubMed

Wilson, S K; Fisher, R; Pratchett, M S; Graham, N A J; Dulvy, N K; Turner, R A; Cakacaka, A; Polunin, N V C

2010-03-01

Overfishing and habitat degradation through climate change pose the greatest threats to sustainability of marine resources on coral reefs. We examined how changes in fishing pressure and benthic habitat composition influenced the size spectra of island-scale reef fish communities in Lau, Fiji. Between 2000 and 2006 fishing pressure declined in the Lau Islands due to declining human populations and reduced demand for fresh fish. At the same time, coral cover declined and fine-scale architectural complexity eroded due to coral bleaching and outbreaks of crown-of-thorns starfish, Acanthaster planci. We examined the size distribution of reef fish communities using size spectra analysis, the linearized relationship between abundance and body size class. Spatial variation in fishing pressure accounted for 31% of the variation in the slope of the size spectra in 2000, higher fishing pressure being associated with a steeper slope, which is indicative of fewer large-bodied fish and/or more small-bodied fish. Conversely, in 2006 spatial variation in habitat explained 53% of the variation in the size spectra slopes, and the relationship with fishing pressure was much weaker (approximately 12% of variation) than in 2000. Reduced cover of corals and lower structural complexity was associated with less steep size spectra slopes, primarily due to reduced abundance of fish < 20 cm. Habitat degradation will compound effects of fishing on coral reefs as increased fishing reduces large-bodied target species, while habitat loss results in fewer small-bodied juveniles and prey that replenish stocks and provide dietary resources for predatory target species. Effective management of reef resources therefore depends on both reducing fishing pressure and maintaining processes that encourage rapid recovery of coral habitat.

Lake Ontario benthic prey fish assessment, 2015

USGS Publications Warehouse

Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

2016-01-01

Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Since the late 1970’s, Lake Ontario benthic prey fish status was primarily assessed using bottom trawl observations confined to the lake’s south shore, in waters from 8 – 150 m (26 – 492 ft). In 2015, the Benthic Prey Fish Survey was cooperatively adjusted and expanded to address resource management information needs including lake-wide benthic prey fish population dynamics. Effort increased from 55 bottom trawl sites to 135 trawl sites collected in depths from 8 - 225m (26 – 738 ft). The spatial coverage of sampling was also expanded and occurred in all major lake basins. The resulting distribution of tow depths more closely matched the available lake depth distribution. The additional effort illustrated how previous surveys were underestimating lake-wide Deepwater Sculpin, Myoxocephalus thompsonii, abundance by not sampling in areas of highest density. We also found species richness was greater in the new sampling sites relative to the historic sites with 11 new fish species caught in the new sites including juvenile Round Whitefish, Prosopium cylindraceum, and Mottled sculpin, Cottus bairdii. Species-specific assessments found Slimy Sculpin, Cottus cognatus abundance increased slightly in 2015 relative to 2014, while Deepwater Sculpin and Round Goby, Neogobius melanostomus, dramatically increased in 2015, relative to 2014. The cooperative, lake-wide Benthic Prey Fish Survey expanded our understanding of benthic fish population dynamics and habitat use in Lake Ontario. This survey’s data and interpretations influence international resource management decision making, such as informing the Deepwater Sculpin conservation status and assessing the balance between sport fish consumption and prey fish populations. Additionally a significant Lake Ontario event occurred in May 2015 when a single

Standard methods for sampling North American freshwater fishes

USGS Publications Warehouse

Bonar, Scott A.; Hubert, Wayne A.; Willis, David W.

2009-01-01

This important reference book provides standard sampling methods recommended by the American Fisheries Society for assessing and monitoring freshwater fish populations in North America. Methods apply to ponds, reservoirs, natural lakes, and streams and rivers containing cold and warmwater fishes. Range-wide and eco-regional averages for indices of abundance, population structure, and condition for individual species are supplied to facilitate comparisons of standard data among populations. Provides information on converting nonstandard to standard data, statistical and database procedures for analyzing and storing standard data, and methods to prevent transfer of invasive species while sampling.

Do management actions to restore rare habitat benefit native fish conservation? Distribution of juvenile native fish among shoreline habitats of the Colorado River

USGS Publications Warehouse

Dodrill, Michael J.; Yackulic, Charles B.; Gerig, Brandon; Pine, William E.; Korman, Josh; Finch, Colton

2015-01-01

Many management actions in aquatic ecosystems are directed at restoring or improving specific habitats to benefit fish populations. In the Grand Canyon reach of the Colorado River, experimental flow operations as part of the Glen Canyon Dam Adaptive Management Program have been designed to restore sandbars and associated backwater habitats. Backwaters can have warmer water temperatures than other habitats, and native fish, including the federally endangered humpback chub Gila cypha, are frequently observed in backwaters, leading to a common perception that this habitat is critical for juvenile native fish conservation. However, it is unknown how fish densities in backwaters compare with that in other habitats or what proportion of juvenile fish populations reside in backwaters. Here, we develop and fit multi-species hierarchical models to estimate habitat-specific abundances and densities of juvenile humpback chub, bluehead suckerCatostomus discobolus, flannelmouth sucker Catostomus latipinnis and speckled dace Rhinichthys osculus in a portion of the Colorado River. Densities of all four native fish were greatest in backwater habitats in 2009 and 2010. However, backwaters are rare and ephemeral habitats, so they contain only a small portion of the overall population. For example, the total abundance of juvenile humpback chub in this study was much higher in talus than in backwater habitats. Moreover, when we extrapolated relative densities based on estimates of backwater prevalence directly after a controlled flood, the majority of juvenile humpback chub were still found outside of backwaters. This suggests that the role of controlled floods in influencing native fish population trends may be limited in this section of the Colorado River. 

Sex Differences in the Relationship between Sleep Behavior, Fish Consumption, and Depressive Symptoms in the General Population of South Korea.

PubMed

Supartini, Atin; Oishi, Taro; Yagi, Nobuyuki

2017-07-14

Sleep, fish consumption, and depression have a close relationship; however, the role of sex differences in sleep, fish consumption, and depression research is not yet well-established. This study aimed to examine whether the impact of bedtime, sleep-onset latency, sleep duration, sleep quality, and fish consumption on depressive symptoms differed in women and men. An online survey was conducted in South Korea with a stratified random sample of 600 participants between the ages of 20 and 69, whose gender and age were proportional to estimates of Korea's general population. The 20-item Center for Epidemiologic Studies Depression Scale was used to measure depressive symptoms with a cut-off score of 16. The Pittsburgh Sleep Quality Index (PSQI) was applied to evaluate sleep timing, sleep-onset latency, sleep duration, and sleep quality. Our results indicated that late bedtime and short sleep duration were independently associated with depressive symptoms in women. Sleep-onset latency and poor sleep quality were independently associated with increased prevalence of depressive symptoms in both men and women. Higher fish consumption was significantly associated with decreased prevalence of depressive symptoms in men only. Our findings suggested the importance of a different approach for men and women in terms of promoting healthy sleep habits. In addition, higher fish consumption may be beneficial in the primary prevention of depression in Korean men. Further research is needed to confirm the findings from this cross-sectional study.

SEASAT economic assessment. Volume 8: Ocean fishing case study. [economic benefits of SEASAT satellites to ocean fishing industries in the United States and Canada

NASA Technical Reports Server (NTRS)

1975-01-01

The potential application of SEASAT data with regard to ocean fisheries is discussed. Tracking fish populations, indirect assistance in forecasting expected populations and assistance to fishing fleets in avoiding costs incurred due to adverse weather through improved ocean conditions forecasts were investigated. Case studies on fisheries in the United States and Canada are cited.

Modifiable risk factors including sunlight exposure and fish consumption are associated with risk of hypertension in a large representative population from Macau.