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.

Return Spawning/Rearing Habitat to Anadromous/Resident Fish within the Fishing Creek to Legendary Bear Creek Analysis Area Watersheds; 2002-2003 Final Report.

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

Taylor, Jr., Emmit E.

2004-03-01

This project is a critical component of currently on-going watershed restoration effort in the Lochsa River Drainage, including the Fishing (Squaw) Creek to Legendary Bear (Papoose) Creek Watersheds Analysis Area. In addition, funding for this project allowed expansion of the project into Pete King Creek and Cabin Creek. The goal of this project is working towards the re-establishment of healthy self-sustaining populations of key fisheries species (spring Chinook salmon, steelhead, bull trout, and westslope cutthroat trout) through returning historic habitat in all life stages (spawning, rearing, migration, and over-wintering). This was accomplished by replacing fish barrier road crossing culverts withmore » structures that pass fish and accommodate site conditions.« less

Patterns of fish assemblage structure and dynamics in waters of the Savannah River Plant. Comprehensive Cooling Water Study final report

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

Aho, J.M.; Anderson, C.S.; Floyd, K.B.

1986-06-01

Research conducted as part of the Comprehensive Cooling Water Study (CCWS) has elucidated many factors that are important to fish population and community dynamics in a variety of habitats on the Savannah River Plant (SRP). Information gained from these studies is useful in predicting fish responses to SRP operations. The overall objective of the CCWS was (1) to determine the environmental effects of SRP cooling water withdrawals and discharges and (2) to determine the significance of the cooling water impacts on the environment. The purpose of this study was to: (1) examine the effects of thermal plumes on anadromous andmore » resident fishes, including overwintering effects, in the SRP swamp and associated tributary streams; (2) assess fish spawning and locate nursery grounds on the SRP; (3) examine the level of use of the SRP by spawning fish from the Savannah River, this objective was shared with the Savannah River Laboratory, E.I. du Pont de Nemours and Company; and (4) determine impacts of cooling-water discharges on fish population and community attributes. Five studies were designed to address the above topics. The specific objectives and a summary of the findings of each study are presented.« less

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-pond snail control, but also include water sources of allochthonous cercariae, i.e. canals supplying water to ponds as well as snail habitats outside the pond such as rice fields and surrounding ponds.

Contracaecum osculatum and other anisakid nematodes in grey seals and cod in the Baltic Sea: molecular and ecological links.

PubMed

Zuo, S; Kania, P W; Mehrdana, F; Marana, M H; Buchmann, K

2018-01-01

Populations of grey seals (Halichoerus grypus), sprats (Sprattus sprattus) and cod (Gadus morhua) in the Baltic Sea are relatively stationary. The present work, applying classical and molecular helminthological techniques, documents that seals and cod also share a common parasite, the anisakid nematode Contracaecum osculatum, which uses seals as the final host and fish as transport hosts. Sequencing mitochondrial genes (COX1 and COX2) in adult worms from seals and third-stage larvae from livers of Baltic fish (sprats and cod), showed that all gene variants occur in both seals and fish. Other anisakid nematodes Pseudoterranova decipiens and Anisakis simplex are also found in both seals and cod in the Baltic Sea, but at much lower rates. The Baltic grey seal population was left at a critically low level (comprising a few hundred individuals) during the latter part of the 20th century, but since the year 2000 a marked increase in the population has been observed, reaching more than 40,000 individuals at present. Ecological consequences of the increased seal abundance may result from increased predation on fish stocks, but recent evidence also points to the influence of elevated parasitism on fish performance. Contracaecum osculatum larvae preferentially infect the liver of Baltic cod, considered a vital organ of the host. Whereas low prevalences and intensities in cod were reported during the 1980s and 1990s, the present study documents 100% prevalence and a mean intensity of above 80 worms per fish. Recent studies have also indicated the zoonotic potential of C. osculatum larvae in fish, following the consumption of raw or under-cooked fish. Therefore the present work discusses the impact of parasitism on the cod stock and the increasing risk for consumer health, and lists possible solutions for control.

Patterns of variations in large pelagic fish: A comparative approach between the Indian and the Atlantic Oceans

NASA Astrophysics Data System (ADS)

Corbineau, A.; Rouyer, T.; Fromentin, J.-M.; Cazelles, B.; Fonteneau, A.; Ménard, F.

2010-07-01

Catch data of large pelagic fish such as tuna, swordfish and billfish are highly variable ranging from short to long term. Based on fisheries data, these time series are noisy and reflect mixed information on exploitation (targeting, strategy, fishing power), population dynamics (recruitment, growth, mortality, migration, etc.), and environmental forcing (local conditions or dominant climate patterns). In this work, we investigated patterns of variation of large pelagic fish (i.e. yellowfin tuna, bigeye tuna, swordfish and blue marlin) in Japanese longliners catch data from 1960 to 2004. We performed wavelet analyses on the yearly time series of each fish species in each biogeographic province of the tropical Indian and Atlantic Oceans. In addition, we carried out cross-wavelet analyses between these biological time series and a large-scale climatic index, i.e. the Southern Oscillation Index (SOI). Results showed that the biogeographic province was the most important factor structuring the patterns of variability of Japanese catch time series. Relationships between the SOI and the fish catches in the Indian and Atlantic Oceans also pointed out the role of climatic variability for structuring patterns of variation of catch time series. This work finally confirmed that Japanese longline CPUE data poorly reflect the underlying population dynamics of tunas.

Log-linear model based behavior selection method for artificial fish swarm algorithm.

PubMed

Huang, Zhehuang; Chen, Yidong

2015-01-01

Artificial fish swarm algorithm (AFSA) is a population based optimization technique inspired by social behavior of fishes. In past several years, AFSA has been successfully applied in many research and application areas. The behavior of fishes has a crucial impact on the performance of AFSA, such as global exploration ability and convergence speed. How to construct and select behaviors of fishes are an important task. To solve these problems, an improved artificial fish swarm algorithm based on log-linear model is proposed and implemented in this paper. There are three main works. Firstly, we proposed a new behavior selection algorithm based on log-linear model which can enhance decision making ability of behavior selection. Secondly, adaptive movement behavior based on adaptive weight is presented, which can dynamically adjust according to the diversity of fishes. Finally, some new behaviors are defined and introduced into artificial fish swarm algorithm at the first time to improve global optimization capability. The experiments on high dimensional function optimization showed that the improved algorithm has more powerful global exploration ability and reasonable convergence speed compared with the standard artificial fish swarm algorithm.

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.

Fish consumption as a driver of risk-management decisions and human health-based water quality criteria.

PubMed

Judd, Nancy; Lowney, Yvette; Anderson, Paul; Baird, Suzanne; Bay, Steven M; Breidt, Jay; Buonanduci, Michele; Dong, Zhao; Essig, Don; Garry, Michael R; Jim, Rebecca C; Kirkwood, Gemma; Moore, Shelly; Niemi, Cheryl; O'Rourke, Rory; Ruffle, Betsy; Schaider, Laurel A; Vidal-Dorsch, Doris E

2015-11-01

The use and interpretation of fish consumption surveys and interviews, the application of fish consumption rates for sediment evaluation and cleanup, and the development of human health water quality criteria (HH WQC) are complex and interrelated issues. The present article focuses on these issues using examples from the United States, although the issues may be relevant for other countries. Some key considerations include the fact that there are many types of fish consumption surveys (e.g., 24-h recall surveys, food frequency questionnaires, creel surveys), and these surveys have different advantages and limitations. Identification of target populations for protection, identification of the species and quantities of fish consumed, and determination of bioaccumulation assumptions are important factors when developing water quality and sediment screening levels and standards. Accounting for the cultural importance of fish consumption for some populations is an even more complex element. Discussions about HH WQC often focus only on the fish consumption rate and may not have broad public input. Some states are trying to change this through extensive public participation efforts and use of probabilistic approaches to derive HH WQC. Finally, there are limits to what WQC can achieve. Solutions beyond the establishment of WQC that target toxics reduction from other sources may provide the greatest improvements to water quality and reductions in human health risks in the future. © 2015 SETAC.

Measurements of spatial population synchrony: influence of time series transformations.

PubMed

Chevalier, Mathieu; Laffaille, Pascal; Ferdy, Jean-Baptiste; Grenouillet, Gaël

2015-09-01

Two mechanisms have been proposed to explain spatial population synchrony: dispersal among populations, and the spatial correlation of density-independent factors (the "Moran effect"). To identify which of these two mechanisms is driving spatial population synchrony, time series transformations (TSTs) of abundance data have been used to remove the signature of one mechanism, and highlight the effect of the other. However, several issues with TSTs remain, and to date no consensus has emerged about how population time series should be handled in synchrony studies. Here, by using 3131 time series involving 34 fish species found in French rivers, we computed several metrics commonly used in synchrony studies to determine whether a large-scale climatic factor (temperature) influenced fish population dynamics at the regional scale, and to test the effect of three commonly used TSTs (detrending, prewhitening and a combination of both) on these metrics. We also tested whether the influence of TSTs on time series and population synchrony levels was related to the features of the time series using both empirical and simulated time series. For several species, and regardless of the TST used, we evidenced a Moran effect on freshwater fish populations. However, these results were globally biased downward by TSTs which reduced our ability to detect significant signals. Depending on the species and the features of the time series, we found that TSTs could lead to contradictory results, regardless of the metric considered. Finally, we suggest guidelines on how population time series should be processed in synchrony studies.

Minimum Pool and Bull Trout Prey Base Investigations at Beulah Reservoir - Final Report for 2008

USGS Publications Warehouse

Rose, Brien P.; Mesa, Matthew G.

2009-01-01

Beulah Reservoir in southeastern Oregon provides irrigation water to nearby farms and supports an adfluvial population of threatened bull trout (Salvelinus confluentus). Summer drawdowns in the reservoir could affect forage fish production and overwintering bull trout. To assess the impacts of drawdown, we sampled fish, invertebrates, and water-quality variables seasonally during 2006-08. In 2006, the summer drawdown was about 68 percent of full pool, which was less than a typical drawdown of 85 percent. We detected few changes in pelagic invertebrate densities, and catch rates, abundance, and sizes of fish when comparing values from spring to values from fall. We did note that densities of benthic insects in areas that were dewatered annually were lower than those from areas that were not dewatered annually. In 2007, the drawdown was 100 percent (to run-of-river level) and resulted in decreases in abundance of invertebrates as much as 96 percent, decreases in catch rates of fish as much as 80 percent, decreases in abundance of redside shiners (Richardsonius balteatus) and northern pikeminnow (Ptychocheilus oregonensis) as much as 93 percent, and decreased numbers of small fish in catches. In the fall 2007, we estimated the total biomass of forage fish to be 76 kilograms, or about one-quarter of total biomass of forage fish in 2006. Bioenergetics modeling suggested that ample forage for about 1,000 bull trout would exist after a moderate drawdown, but that forage remaining after a complete dewatering would not be sufficient for a population one-fifth the size. Our results indicate that drawdowns in Beulah Reservoir affect the aquatic community and perhaps the health and well-being of bull trout. The severity of effects depends on the extent of drawdown, population size of bull trout, and perhaps other factors.

The ecology of cormorants: some research needs and recommendations

USGS Publications Warehouse

Erwin, R.M.; Nettleship, David N.; Duffy, David C.

1995-01-01

Concerns about Double-crested Cormorants (Phalacrocorax auritus) have arisen because of their rapid population increase across North America and their economic impact on several aquaculture and commercial fish industries. In spite of the concern for cormorants, little published research is available that addresses either basic population biology questions or management issues. Based on a literature review, I recommend that research be conducted in four areas. First, a large-scale banding and marking program should be initiated so that population models can be used to estimate age- and sex-specific survival and fecundity (as has been done for the Shag [P. aristotelis] in Europe). By marking individual birds, survival and movement rates can be estimated between nesting colonies, which will provide information about potential source versus sink colonies. Second, studies of movements during migration and winter are required. Presently, no data are available on habitat use during migration or on the length-of-stay by individual birds. This has important implications to how cormorants interact with other fish and wildlife species over a broad range. Studies of movements during winter with radio-marked birds should indicate whether the 'problem birds' at aquaculture sites are merely a few specialists. Third, limiting factors, such as contaminants and disease, should receive further investigation, especially in light of recent concerns over the outbreak of Newcastle disease. The relationship between contaminant levels and developmental abnormalities in young cormorants in certain areas of the Great Lakes in Canada and the United States remains equivocal. Fourth, further studies are needed to document the economic impacts of cormorants on Channel Catfish (Ictalurus punctatus) and other cultured fishes and to determine ways to reduce predation by fish-eating birds. Mesocosm experiments should be conducted to evaluate how different fish extraction rates affect final productivity of fish. Controlled experiments with different exclusion and scaring devices are needed. With radio-marked birds, it should be determined what the behavioral responses are to the different scaring devises. Also, providing alternative wetland feeding sites in regions of fish farm depredation might alleviate some of the pressure on farmers. Studies with radio-marked birds could evaluate effects of manipulation of 'natural' wetlands on use by birds during the winter period. Finally, any research directed at the Double-crested Cormorant should also evaluate its interactions with other fisheating waterbirds.

Log-Linear Model Based Behavior Selection Method for Artificial Fish Swarm Algorithm

PubMed Central

Huang, Zhehuang; Chen, Yidong

2015-01-01

Artificial fish swarm algorithm (AFSA) is a population based optimization technique inspired by social behavior of fishes. In past several years, AFSA has been successfully applied in many research and application areas. The behavior of fishes has a crucial impact on the performance of AFSA, such as global exploration ability and convergence speed. How to construct and select behaviors of fishes are an important task. To solve these problems, an improved artificial fish swarm algorithm based on log-linear model is proposed and implemented in this paper. There are three main works. Firstly, we proposed a new behavior selection algorithm based on log-linear model which can enhance decision making ability of behavior selection. Secondly, adaptive movement behavior based on adaptive weight is presented, which can dynamically adjust according to the diversity of fishes. Finally, some new behaviors are defined and introduced into artificial fish swarm algorithm at the first time to improve global optimization capability. The experiments on high dimensional function optimization showed that the improved algorithm has more powerful global exploration ability and reasonable convergence speed compared with the standard artificial fish swarm algorithm. PMID:25691895

Columbia River White Sturgeon (Acipenser Transmontanus) Early Life History and Genertics Study, August 1, 1984 to December 31, 1985 Final Report.

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

Brannon, Ernest L.

1985-12-01

Research on Columbia River white sturgeon has been directed at their early life history as it may apply to production and enhancement strategies for management of the species. The river environment in which sturgeon historically migrated, spawned, and reared has changed through development. Habitat changes are expected to precipitate genetic changes in the fish, as well as reduce the fitness in populations. Genetic analysis of samples taken from various locations over the length of the Columbia River have indicated that observed gene frequencies in all areas sampled were not in Hardy-Weinburg equilibrium, which could suggest that the general population ismore » experiencing perturbation in the system. Analysis thus far has exposed few differences between samples from the lower, middle, and upper portions of the system. Allelic differences were identified in fish from the Roosevelt Lake, which may be evidence of unique characteristics among fish from that general area.« less

Atrazine reduces reproduction in fathead minnow (Pimephales promelas)

USGS Publications Warehouse

Tillitt, D.E.; Papoulias, D.M.; Whyte, J.J.; Richter, C.A.

2010-01-01

Atrazine, the widely used herbicide, has shown to affect the hypothalamus-pituitary-gonad axis in certain vertebrate species, but few studies have examined reproductive effects of this chemical on fish. Our study was designed to evaluate a population endpoint (egg production) in conjunction with histological (e.g., gonad development) and biochemical (e.g., hormone production) phenotypes associated with atrazine exposure in fathead minnows. Adult virgin breeding groups of 1 male and 2 females were exposed to nominal concentrations of 0, 0.5, 5.0, and 50 ??g/L of atrazine in a flow-through diluter for 14 or 30 days. Total egg production was lower (19-39%) in all atrazine-exposed groups as compared to the controls. The decreases in cumulative egg production of atrazine treated fish were significant by 17-20 days of exposure. Reductions in egg production in atrazine treatment groups were most attributable to reduced numbers of spawning events with increased atrazine exposure concentrations. Gonad abnormalities were observed in both male and female fish of atrazine-exposed fish. Our results also indicate that atrazine reduces egg production through alteration of final maturation of oocytes. The reproductive effects observed in this study warrant further investigation and evaluation of the potential risks posed by atrazine, particularly feral populations of fish from streams in agricultural areas with high use of this herbicide. ?? 2010.

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 Intermountain West to the increasing threat of wildfire.

A framework for assessing the feasibility of native fish conservation translocations: Applications to threatened bull trout

USGS Publications Warehouse

Galloway, Benjamin T.; Muhlfeld, Clint C.; Guy, Christopher S.; Downs, Christopher C.; Fredenberg, Wade A.

2016-01-01

There is an urgent need to consider more aggressive and direct interventions for the conservation of freshwater fishes that are threatened by invasive species, habitat loss, and climate change. Conservation introduction (moving a species outside its indigenous range to other areas where conditions are predicted to be more suitable) is one type of translocation strategy that fisheries managers can use to establish new conservation populations in areas of refugia. To date, however, there are few examples of successful conservation-based introductions. Many attempts fail to establish new populations—in part because environmental factors that might influence success are inadequately evaluated before the translocation is implemented. We developed a framework to assess the feasibility of rescuing threatened fish populations through translocation into historically unoccupied stream and lake habitats. The suitability of potential introduction sites was evaluated based on four major components: the recipient habitat, recipient community, donor population, and future threats. Specific questions were then developed to evaluate each major component. The final assessment was based on a scoring system that addressed each question by using criteria developed from characteristics representative of highly suitable habitats and populations. This framework was used to evaluate the proposed within-drainage translocation of three Bull Trout Salvelinus confluentus populations in Glacier National Park, Montana. Our results indicated that within-drainage translocation is a feasible strategy for conserving locally adapted populations of Bull Trout through the creation of new areas of refugia in Glacier National Park. The framework provides a flexible platform that can help managers make informed decisions for moving threatened fishes into new areas of refugia for conservation and recovery programs.

Application of AN Empirically Scaled Digital Echo Integrator for Assessment of Juvenile Sockeye Salmon (oncorhynchus Nerka Walbaum) Populations.

NASA Astrophysics Data System (ADS)

Nunnallee, Edmund Pierce, Jr.

1980-03-01

This dissertation consists of an investigation into the empirical scaling of a digital echo integrator for assessment of a population of juvenile sockeye salmon in Cultus Lake, British Columbia, Canada. The scaling technique was developed over the last ten years for use with totally uncalibrated but stabilized data collection and analysis equipment, and has been applied to populations of fish over a wide geographical range. This is the first investigation into the sources of bias and the accuracy of the technique, however, and constitutes a verification of the method. The initial section of the investigation describes hydroacoustic data analysis methods for estimation of effective sampling volume which is necessary for estimation of fish density. The second section consists of a computer simulation of effective sample volume estimation by this empirical method and is used to investigate the degree of bias introduced by electronic and physical parameters such as boat speed -fish depth interaction effects, electronic thresholding and saturation, transducer beam angle, fish depth stratification by size and spread of the target strength distribution of the fish. Comparisons of simulation predictions of sample volume estimation bias to actual survey results are given at the end of this section. A verification of the scaling method is then presented by comparison of a hydroacoustically derived estimation of the Cultus Lake smolt population to an independent and concurrent estimate made by counting the migrant fish as they passed through a weir in the outlet stream of the lake. Finally, the effect on conduct and accuracy of hydroacoustic assessment of juvenile sockeye salmon due to several behavioral traits are discussed. These traits include movements of presmolt fish in a lake just prior to their outmigration, daily vertical migrations and the emergence and dispersal of sockeye fry in Cultus Lake. In addition, a comparison of the summer depth preferences of the fish over their entire geographical distribution on the west coast of the U.S. and Canada are discussed in terms of hydroacoustic accessibility.

South Fork Flathead Watershed Westslope Cutthroat Trout Conservation Program, Annual Report 2002.

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

Grisak, Grant; Marotz, Brian

2003-06-01

In 1999, Montana Fish, Wildlife & Parks (MFWP) began a program aimed at conserving the genetically pure populations of westslope cutthroat trout in the South Fork Flathead River drainage. The objective of this program is to eliminate all of the exotic and hybrid trout that threaten the genetically pure westslope cutthroat populations in the South Fork Flathead. The exotic and hybrid trout populations occur in several headwater lakes and their outflow streams. In 2001 MFWP released a draft environmental assessment, pursuant to the Montana Environmental Policy Act (MEPA), that addressed the use of motorized equipment to deliver personnel and materialsmore » to some of these lakes in the Bob Marshall and Great Bear Wildernesses (Grisak 2001). After a 30-day public comment period, MFWP determined that the complexity of issues was too great and warranted a more detailed analysis. These issues included transportation options for personnel, equipment and materials, the use of motorized equipment in wilderness, fish removal methods, fish stocking, and the status and distribution of amphibian populations in the project area. Because the program also involves the U.S. Forest Service (USFS) and Bonneville Power Administration (BPA), the environmental analysis needs to comply with the National Environmental Policy Act (NEPA). In October 2001, pursuant to NEPA, MFWP, along with the USFS and BPA initiated an environmental assessment to address these issues. In June 2002, the three agencies determined that the scope of these issues warranted an Environmental Impact Statement. This specialist report describes the logistical, technical and biological issues associated with this project and provides an analysis of options for fish removal, transportation and fish stocking. It further analyzes issues and concerns associated with amphibian populations and creating new domesticated stocks of westslope cutthroat trout. Finally, this document provides a description of each lake, the best method of fish removal that would achieve the goals of the project, logistics for carrying out the fish removal, and the immediate management direction for each lake following fish removal. The USFS is preparing a specialist report detailing land management issues that relate to National Forest, designated Hiking Areas, and Wilderness. Information from these two documents will be used by BPA to prepare an Environmental Impact Statement.« less

Testing for genetic differences in survival and growth between hatchery and wild Chinook salmon from Warm Springs River, Oregon (Study sites: Warm Springs Hatchery and Little White Salmon River; Stocks: Warm Springs hatchery and Warm Springs River wild; Year classes: 1992 and 1996): Chapter 8

USGS Publications Warehouse

Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Leonetti,; Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Hayes, Michael C.

2012-01-01

The program at Warm Springs National Fish Hatchery in north - central Oregon was initiated with spring Chinook salmon Oncorhynchus tshawytscha from the Warm Springs River. Managers included wild fish in the broodstock most years and avoided artificial selection to minimize genetic divergence from the wild founder population. We tested for genetic differences in survival and growth between the hatchery and wild populations to ascertain whether this goal has been achieved. Progeny of hatchery x hatchery (HH), hatchery female x wild male (HW), and wild x wild (WW) crosses were genetically marked at the sSOD - 1* allozyme locus and released together as unfed fry in hatchery ponds in 1992 and 1996 and in the Little White Salmon River, in south - central Washington, in 1996. Fish were evaluated to returning adult at the hatchery and over their freshwater residence of 16 months in the stream. The three crosses differed on several measures including survival to outmigration in the stream (WW>HH>HW) and juvenile growth in the hatchery (1992 year - class; WW>HW>HH); however, results may have been confounded. The genetic marks were found to differentially effect survival in a companion study (HH mark favored over WW mark; HW mark intermediate). Furthermore, HW survival in the current study was neither intermediate, as would be expect ed from additive genetic effects, nor similar to that of HH fish as would be expected from maternal effects since HW and HH fish were maternal half - siblings. Finally, the unexpected performance of HW fish precludes ruling out maternal differences between hatchery and wild mothers as the cause of differences between HH and WW fish. The key finding that survival of HH fish in a stream was 0.91 that for WW fish, indicating a small loss of fitness for natural rearing in the hatchery population, is valid only if three conditions hold: (1) any selection on the genetic marks was in the same direction as in the companion study, (2) lower survival in the stream for HW than for HH fish resulted because some HW families were genetically atypical, not from problems w ith either pure type, and (3) lower survival for HH than for WW fish was not due to maternal effects. Although all three conditions had support, none of it was conclusive. This study provides only suggestions, not definitive answers for the primary quest ion of whether the hatchery population has diverged genetically from its wild founder population in fitness - related traits.

Identifying alternate pathways for climate change to impact inland recreational fishers

USGS Publications Warehouse

Hunt, Len M.; Fenichel, Eli P.; Fulton, David C.; Mendelsohn, Robert; Smith, Jordan W.; Tunney, Tyler D.; Lynch, Abigail J.; Paukert, Craig P.; Whitney, James E.

2016-01-01

Fisheries and human dimensions literature suggests that climate change influences inland recreational fishers in North America through three major pathways. The most widely recognized pathway suggests that climate change impacts habitat and fish populations (e.g., water temperature impacting fish survival) and cascades to impact fishers. Climate change also impacts recreational fishers by influencing environmental conditions that directly affect fishers (e.g., increased temperatures in northern climates resulting in extended open water fishing seasons and increased fishing effort). The final pathway occurs from climate change mitigation and adaptation efforts (e.g., refined energy policies result in higher fuel costs, making distant trips more expensive). To address limitations of past research (e.g., assessing climate change impacts for only one pathway at a time and not accounting for climate variability, extreme weather events, or heterogeneity among fishers), we encourage researchers to refocus their efforts to understand and document climate change impacts to inland fishers.

Habitat modeling for brown trout population in alpine region of Slovenia with focus on determination of preference functions, fuzzy rules and fuzzy sets

NASA Astrophysics Data System (ADS)

Santl, Saso; Carf, Masa; Preseren, Tanja; Jenic, Aljaz

2013-04-01

Water withdrawals and consequently reduction of discharges in river streams for different water uses (hydro power, irrigation, etc.) usually impoverish habitat suitability for naturally present river fish fauna. In Slovenia reduction of suitable habitats resulting from water abstractions frequently impacts local brown trout (Salmo truta) populations. This is the reason for establishment of habitat modeling which can qualitatively and quantitatively support decision making for determination of the environmental flow and other mitigation measures. Paper introduces applied methodology for habitat modeling where input data preparation and elaboration with required accuracy has to be considered. For model development four (4) representative and heterogeneous sampling sites were chosen. Two (2) sampling sections were located within the sections with small hydropower plants and were considered as sections affected by water abstractions. The other two (2) sampling sections were chosen where there are no existing water abstractions. Precise bathymetric mapping for chosen river sections has been performed. Topographic data and series of discharge and water level measurements enabled establishment of calibrated hydraulic models, which provide data on water velocities and depths for analyzed discharges. Brief field measurements were also performed to gather required data on dominant and subdominant substrate size and cover type. Since the accuracy of fish distribution on small scale is very important for habitat modeling, a fish sampling method had to be selected and modified for existing river microhabitats. The brown trout specimen's locations were collected with two (2) different sampling methods. A method of riverbank observation which is suitable for adult fish in pools and a method of electro fishing for locating small fish and fish in riffles or hiding in cover. Ecological and habitat requirements for fish species vary regarding different fish populations as well as eco and hydro morphological types of streams. Therefore, if habitat modeling for brown trout in Slovenia should be applied, it is necessary to determine preference requirements for the locally present brown trout populations. For efficient determination of applied preference functions and linked fuzzy sets/rules, beside expert determination, calibration according to field sampling must also be performed. After this final step a model is prepared for the analysis to support decision making in the field of environmental flow and other mitigation measures determination.

Evaluating and understanding fish health risks and their consequences in propagated and free-ranging fish populations

USGS Publications Warehouse

Moffitt, C.M.; Haukenes, A.H.; Williams, C.J.

2005-01-01

Fishery managers and resource conservationists are increasingly interested in understanding the fish health and disease risks of free-ranging fishes and whether propagated fishes or features and practices used at fish culture facilities pose a health risk to free-ranging populations. Disease agents are present in most both captive and all free-ranging fish populations, but the consequences and extent of infections in free-ranging populations are often difficult to measure, control, and understand. Sampling methods, protocols, and assay techniques developed to assess the health of captive populations are not as applicable for assessments of free-ranging fishes. The use of chemicals and therapeutics to control diseases and parasites in propagated fishes likely reduces the risk of introducing specific pathogens into the environment, but control measures may have localized effects on the environment surrounding fish culture facilities. To understand health risks of propagated and free ranging fishes, we must consider fish populations, culture facilities, fish releases, and their interactions within the greater geospatial features of the aquatic environment. ?? 2004 by the American Fisheries Society.

Parasites of forage fishes in the vicinity of Steller sea lion (Eumetopias jubatus) habitat in Alaska.

PubMed

Moles, A; Heintz, R A

2007-07-01

Fish serve as intermediate hosts for a number of larval parasites that have the potential of maturing in marine mammals such as Steller sea lions (Eumetopias jubatus). We examined the prevalence of parasites from 229 fish collected between March and July 2002 near two islands used by Steller sea lions in Southeast Alaska and island habitats in the Aleutian Islands. Sea lion populations have remained steady in Southeast Alaska but have been declining over the last 30 yr in the Aleutian Islands. Even though the fish samples near the Southeast Alaska haul-outs were composed of numerous small species of fish and the Aleutian Islands catch was dominated by juveniles of commercially harvested species, the parasite fauna was similar at all locations. Eleven of the 20 parasite taxa identified were in their larval stage in the fish hosts, several of which have been described from mammalian final hosts. Four species of parasite were more prevalent in Southeast Alaska fish samples, and seven parasite species, including several larval forms capable of infecting marine mammals, were more prevalent in fish from the Aleutian Islands. Nevertheless, parasites available to Steller sea lions from common fish prey are not likely to be a major factor in the decline of this marine mammal species.

Effect of the Operation of Kerr and Hungry Horse Dams on the Reproductive Success of Kokanee in the Flathead System; Technical Addendum to the Final Report.

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

Beattie, Will; Tohtz, Joel

1990-03-01

This addendum to the Final Report presents results of research on the zooplankton and fish communities of Flathead Lade. The intent of the Study has been to identify the impacts of hydroelectric operations at Kerr and Hungry Horse Dam on the reproductive success of kokanee an to propose mitigation for these impacts. Recent changes in the trophic ecology of the lake, have reduced the survival of kokanee. In the last three year the Study has been redirected to identify, if possible, the biological mechanisms which now limit kokanee survival, and to test methods of enhancing the kokanee fishery by artificialmore » supplementation. These studies were necessary to the formulation of mitigation plans. The possibility of successfully rehabilitating the kokanee population, is the doubt because of change in the trophic ecology of the system. This report first presents the results of studies of the population dynamics of crustacean zooplankton, upon which planktivorous fish depend. A modest effort was directed to measuring the spawning escapement of kokanee in 1988. Because of its relevance to the study, we also report assessments of 1989 kokanee spawning escapement. Hydroacoustic assessment of the abundance of all fish species in Flathead Lake was conducted in November, 1988. Summary of the continued efforts to document the growth rates and food habits of kokanee and lake whitefish are included in this report. Revised kokanee spawning and harvest estimates, and management implications of the altered ecology of Flathead Lake comprise the final sections of this addendum. 83 refs., 20 figs., 25 tabs.« less

Temporal changes in blood variables during final maturation and senescence in male sockeye salmon Oncorhynchus nerka: reduced osmoregulatory ability can predict mortality.

PubMed

Jeffries, K M; Hinch, S G; Donaldson, M R; Gale, M K; Burt, J M; Thompson, L A; Farrell, A P; Patterson, D A; Miller, K M

2011-08-01

This study is the first to characterize temporal changes in blood chemistry of individuals from one population of male sockeye salmon Oncorhynchus nerka during the final 6 weeks of sexual maturation and senescence in the freshwater stage of their spawning migration. Fish that died before the start of their historic mean spawning period (c. 5 November) were characterized by a 20-40% decrease in plasma osmolality, chloride and sodium, probably representing a complete loss of osmoregulatory ability. As fish became moribund, they were further characterized by elevated levels of plasma cortisol, lactate and potassium. Regressions between time to death and plasma chloride (8 October: P < 0·001; 15 October: P < 0·001) indicate that plasma chloride was a strong predictor of longevity in O. nerka. That major plasma ion levels started to decline 2-10 days (mean of 6 days) before fish became moribund, and before other stress, metabolic or reproductive hormone variables started to change, suggests that a dysfunctional osmoregulatory system may initiate rapid senescence and influence other physiological changes (i.e. elevated stress and collapsed reproductive hormones) which occur as O. nerka die on spawning grounds. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

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.

An advection-diffusion-reaction size-structured fish population dynamics model combined with a statistical parameter estimation procedure: application to the Indian ocean skipjack tuna fishery.

PubMed

Faugeras, Blaise; Maury, Olivier

2005-10-01

We develop an advection-diffusion size-structured fish population dynamics model and apply it to simulate the skipjack tuna population in the Indian Ocean. The model is fully spatialized, and movements are parameterized with oceanographical and biological data; thus it naturally reacts to environment changes. We first formulate an initial-boundary value problem and prove existence of a unique positive solution. We then discuss the numerical scheme chosen for the integration of the simulation model. In a second step we address the parameter estimation problem for such a model. With the help of automatic differentiation, we derive the adjoint code which is used to compute the exact gradient of a Bayesian cost function measuring the distance between the outputs of the model and catch and length frequency data. A sensitivity analysis shows that not all parameters can be estimated from the data. Finally twin experiments in which pertubated parameters are recovered from simulated data are successfully conducted.

Natural bounds on herbivorous coral reef fishes

PubMed Central

Hoey, Andrew S.; Williams, Gareth J.; Williams, Ivor D.

2016-01-01

Humans are an increasingly dominant driver of Earth's biological communities, but differentiating human impacts from natural drivers of ecosystem state is crucial. Herbivorous fish play a key role in maintaining coral dominance on coral reefs, and are widely affected by human activities, principally fishing. We assess the relative importance of human and biophysical (habitat and oceanographic) drivers on the biomass of five herbivorous functional groups among 33 islands in the central and western Pacific Ocean. Human impacts were clear for some, but not all, herbivore groups. Biomass of browsers, large excavators, and of all herbivores combined declined rapidly with increasing human population density, whereas grazers, scrapers, and detritivores displayed no relationship. Sea-surface temperature had significant but opposing effects on the biomass of detritivores (positive) and browsers (negative). Similarly, the biomass of scrapers, grazers, and detritivores correlated with habitat structural complexity; however, relationships were group specific. Finally, the biomass of browsers and large excavators was related to island geomorphology, both peaking on low-lying islands and atolls. The substantial variability in herbivore populations explained by natural biophysical drivers highlights the need for locally appropriate management targets on coral reefs. PMID:27881745

Maturation and fecundity of a stock-enhanced population of striped bass in the Savannah River Estuary, U.S.A.

USGS Publications Warehouse

Will, T.A.; Reinert, T.R.; Jennings, C.A.

2002-01-01

The striped bass Morone saxatilis population in the Savannah River (south-eastern U.S.A.) collapsed in the 1980s, and recent efforts to restore the population have resulted in increased catch-per-unit-effort (CPUE) of striped bass in the Savannah River Estuary (SRE). The abundance of eggs and larvae, however, remain well below historic levels. The primary cause of the population decline was remedied, and environmental conditions seem suitable for striped bass spawning. Regression analysis of data derived from ultrasonic imaging of 31 striped bass resulted in a statistical model that predicted ovary volume well (r2=0.95). The enumeration of oocytes from ovarian tissue samples and the prediction of ovary volume allowed fecundity to be estimated without sacrificing the fish. Oocyte maturation in Savannah River striped bass seemed to progress normally, with oocytes developing to final stages of maturity in larger fish (>750 mm LT). Additionally, fecundity estimates were comparable to a neighbouring striped bass population. The environmental cues needed to trigger development and release of striped bass oocytes into the SRE appeared to be present. If most of the striped bass females in the SRE are still young (<7 years), the ability to produce large numbers of eggs will be limited. As these young fish mature, egg production probably will increase and the density of striped bass eggs eventually will approach historic levels, provided suitable habitat and water quality are maintained. ?? 2002 The Fisheries Society of the British Isles.

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.

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

Leong, JoAnn Ching

The main objective for this study was the development of a rapid diagnostic method for IHN virus in fish tissue samples. The rationale for developing new techniques for diagnosing IHNV infection was that present methods were time consuming and dependent on virus neutralization by specific antisera, a reagent that was not readily available or reliable. Fish pathologists required a rapid detection method which was sensitive enough to detect virus strain differences so that they could provide data for effective management decisions in controlling the spread of IHNV. Bonneville Power Administration's (BPA) role in efforts in fish diseases and more genericallymore » the protection, mitigation, and enhancement of Columbia River salmon and steelhead populations, is mandated by Congress through the Pacific Northwest Electric Power Planning and Conservation Act (Regional Act), Pub. L. 96-501. Section 4 (h) of the Regional Act directs the Northwest Power Planning Council to develop a Fish and Wildlife Program. BPA's Administrator is authorized in Section 4 (h) (10) (A) to ''use funds and the authorities available to the extent affected by the development and operation of any hydroelectric project of the Columbia River and its tributaries''. The fund is to be used to implement measures that are consistent with the Council's Fish and Wildlife Program. The research detailed in this final report is consistent with these objectives. This final report has been prepared as part of BPA's policy to encourage the preservation and dissemination of research results by publication in scientific journals.« less

From 'omics to otoliths: responses of an estuarine fish to endocrine disrupting compounds across biological scales.

PubMed

Brander, Susanne M; Connon, Richard E; He, Guochun; Hobbs, James A; Smalling, Kelly L; Teh, Swee J; White, J Wilson; Werner, Inge; Denison, Michael S; Cherr, Gary N

2013-01-01

Endocrine disrupting chemicals (EDCs) cause physiological abnormalities and population decline in fishes. However, few studies have linked environmental EDC exposures with responses at multiple tiers of the biological hierarchy, including population-level effects. To this end, we undertook a four-tiered investigation in the impacted San Francisco Bay estuary with the Mississippi silverside (Menidia audens), a small pelagic fish. This approach demonstrated links between different EDC sources and fish responses at different levels of biological organization. First we determined that water from a study site primarily impacted by ranch run-off had only estrogenic activity in vitro, while water sampled from a site receiving a combination of urban, limited ranch run-off, and treated wastewater effluent had both estrogenic and androgenic activity. Secondly, at the molecular level we found that fish had higher mRNA levels for estrogen-responsive genes at the site where only estrogenic activity was detected but relatively lower expression levels where both estrogenic and androgenic EDCs were detected. Thirdly, at the organism level, males at the site exposed to both estrogens and androgens had significantly lower mean gonadal somatic indices, significantly higher incidence of severe testicular necrosis and altered somatic growth relative to the site where only estrogens were detected. Finally, at the population level, the sex ratio was significantly skewed towards males at the site with measured androgenic and estrogenic activity. Our results suggest that mixtures of androgenic and estrogenic EDCs have antagonistic and potentially additive effects depending on the biological scale being assessed, and that mixtures containing androgens and estrogens may produce unexpected effects. In summary, evaluating EDC response at multiple tiers is necessary to determine the source of disruption (lowest scale, i.e. cell line) and what the ecological impact will be (largest scale, i.e. sex ratio).

Can epidemiological studies discern subtle neurological effects due to perinatal exposure to PCBs?

PubMed

Seegal, R F

1996-01-01

What conclusions can be drawn concerning the potential neurological effects of perinatal exposure to either PCBs, or PCBs and other fish-borne contaminants? First, by their very nature epidemiological studies are limited in their ability to detect subtle associations--including possible links between exposure to low levels of environmental contaminants and disease. As stated by Dr. Schantz, both Rogan and the Jacobsons report small changes in motor and cognitive behavior--typically less than one-half of a standard deviation--and only in the most highly exposed children. Given these small changes in CNS function, the substantive criticisms of Paneth (including the Jacobsons' choice to employ a random, rather than matched, control sample and the related fact that fish-eating mothers differed from non-fish-eating mothers on several important characteristics) and similar "generic" concerns raised by Taubes, a critical reader must question both the validity of the findings from the Michigan study and the reasons for discrepancies in results between the Jacobson and Rogan studies. Are the differences in neurobehavioral effects reported by the Jacobsons and colleagues, and Rogan and colleagues, due to the presence of confounders, exposure to different neurotoxicants, or subtle differences in methodologies? At present it is not possible to answer these questions. Nevertheless, certain commonalities exist between the Rogan and Jacobson studies, and most recently, the study conducted by Daly and colleagues in New York. All of these studies report alterations in the Brazelton Neonatal Behavioral Assessment Scale, suggesting that exposure to environmental contaminants (including PCBs) may induce subtle, transient alterations in maturation of the human CNS. Secondly, because contaminated fish contain a large number of putative developmental neurotoxicants (e.g., methyl-mercury, p,p'-DDE, PCBs, and pesticides), I am pessimistic that additional studies of human populations exposed to contaminated aquatic and marine fish and mammals will allow investigators to determine which contaminant(s) may be responsible for the observed association between fish consumption and neurobehavioral deficits. For example, although PCB body burdens have been measured in the majority of the epidemiological studies, PCBs may simply reflect exposure to other fish-borne contaminants. In light of the above statements, future epidemiological studies should focus on highly exposed susceptible populations such as occupationally exposed workers or the aged. Results from these studies would provide important information on the risk of perinatal or adult exposure to PCBs in susceptible populations, although generalization of results obtained in these populations to the general population may be fraught with difficulties. Finally, because of the limitations of epidemiological studies, particularly those studying fish-eating populations, future risk assessments should depend more heavily on laboratory derived data, including studies in nonhuman primates exposed to environmentally relevant mixtures and relevant doses of PCB congeners and other known or suspected neurotoxicants.

Fluorescence in situ hybridization (CARD-FISH) of microorganisms in hydrocarbon contaminated aquifer sediment samples.

PubMed

Tischer, Karolin; Zeder, Michael; Klug, Rebecca; Pernthaler, Jakob; Schattenhofer, Martha; Harms, Hauke; Wendeberg, Annelie

2012-12-01

Groundwater ecosystems are the most important sources of drinking water worldwide but they are threatened by contamination and overexploitation. Petroleum spills account for the most common source of contamination and the high carbon load results in anoxia and steep geochemical gradients. Microbes play a major role in the transformation of petroleum hydrocarbons into less toxic substances. To investigate microbial populations at the single cell level, fluorescence in situ hybridization (FISH) is now a well-established technique. Recently, however, catalyzed reporter deposition (CARD)-FISH has been introduced for the detection of microbes from oligotrophic environments. Nevertheless, petroleum contaminated aquifers present a worst case scenario for FISH techniques due to the combination of high background fluorescence of hydrocarbons and the presence of small microbial cells caused by the low turnover rates characteristic of groundwater ecosystems. It is therefore not surprising that studies of microorganisms from such sites are mostly based on cultivation techniques, fingerprinting, and amplicon sequencing. However, to reveal the population dynamics and interspecies relationships of the key participants of contaminant degradation, FISH is an indispensable tool. In this study, a protocol for FISH was developed in combination with cell quantification using an automated counting microscope. The protocol includes the separation and purification of microbial cells from sediment particles, cell permeabilization and, finally, CARD-FISH in a microwave oven. As a proof of principle, the distribution of Archaea and Bacteria was shown in 60 sediment samples taken across the contaminant plume of an aquifer (Leuna, Germany), which has been heavily contaminated with several ten-thousand tonnes of petroleum hydrocarbons since World War II. Copyright © 2012 Elsevier GmbH. All rights reserved.

In vitro leukocyte response of three-spined sticklebacks (Gasterosteus aculeatus) to helminth parasite antigens.

PubMed

Franke, Frederik; Rahn, Anna K; Dittmar, Janine; Erin, Noémie; Rieger, Jennifer K; Haase, David; Samonte-Padilla, Irene E; Lange, Joseph; Jakobsen, Per J; Hermida, Miguel; Fernández, Carlos; Kurtz, Joachim; Bakker, Theo C M; Reusch, Thorsten B H; Kalbe, Martin; Scharsack, Jörn P

2014-01-01

Helminth parasites of teleost fish have evolved strategies to evade and manipulate the immune responses of their hosts. Responsiveness of fish host immunity to helminth antigens may therefore vary depending on the degree of host-parasite counter-adaptation. Generalist parasites, infective for a number of host species, might be unable to adapt optimally to the immune system of a certain host species, while specialist parasites might display high levels of adaptation to a particular host species. The degree of adaptations may further differ between sympatric and allopatric host-parasite combinations. Here, we test these hypotheses by in vitro exposure of head kidney leukocytes from three-spined sticklebacks (Gasterosteus aculeatus) to antigens from parasites with a broad fish host range (Diplostomum pseudospathaceum, Triaenophorus nodulosus), a specific fish parasite of cyprinids (Ligula intestinalis) and parasites highly specific only to a single fish species as second intermediate host (Schistocephalus pungitii, which does not infect G. aculeatus, and Schistocephalus solidus, infecting G. aculeatus). In vitro responses of stickleback leukocytes to S. solidus antigens from six European populations, with S. solidus prevalence from <1% to 66% were tested in a fully crossed experimental design. Leukocyte cultures were analysed by means of flow cytometry and a chemiluminescence assay to quantify respiratory burst activity. We detected decreasing magnitudes of in vitro responses to antigens from generalist to specialist parasites and among specialists, from parasites that do not infect G. aculeatus to a G. aculeatus-infecting species. Generalist parasites seem to maintain their ability to infect different host species at the costs of relatively higher immunogenicity compared to specialist parasites. In a comparison of sympatric and allopatric combinations of stickleback leukocytes and antigens from S. solidus, magnitudes of in vitro responses were dependent on the prevalence of the parasite in the population of origin, rather than on sympatry. Antigens from Norwegian (prevalence 30-50%) and Spanish (40-66%) S. solidus induced generally higher in vitro responses compared to S. solidus from two German (<1%) populations. Likewise, leukocytes from stickleback populations with a high S. solidus prevalence showed higher in vitro responses to S. solidus antigens compared to populations with low S. solidus prevalence. This suggests a rather low degree of local adaptation in S. solidus populations, which might be due to high gene flow among populations because of their extremely mobile final hosts, fish-eating birds. Copyright © 2013 Elsevier Ltd. All rights reserved.

Recovery monitoring of pigeon guillemot populations in Prince William Sound, Alaska. Restoration project 94173. Exxon Valdez oil spill restoration project final report

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

Hayes, D.L.

1995-05-01

The population of pigeon guillemots in Prince William Sound decreased from about 15,000 (1970`s) to about 5,000 (present). Some local populations were affected by the U/V Exxon Valdez oil spill in 1989, but there is evidence suggesting the Sound-wide population was already declining. Predation was the cause of numerous nesting failures. Abandonment of eggs was also high. Changes in the relative proportions of benthic and schooling fish in the diet of guillemot chicks might represent a key change in the ecosystem that is affecting other species of marine birds and mammals in the Sound.

Metazoan parasite infection in the swordfish, Xiphias gladius, from the Mediterranean Sea and comparison with Atlantic populations: implications for its stock characterization

PubMed Central

Mattiucci, Simonetta; Garcia, Alexandra; Cipriani, Paolo; Santos, Miguel Neves; Nascetti, Giuseppe; Cimmaruta, Roberta

2014-01-01

Thirteen parasite taxa were identified in the Mediterranean swordfish by morphological and genetic/molecular methods. The comparison of the identified parasite taxa and parasitic infection values observed in the Mediterranean swordfish showed statistically significant differences with respect to those reported for its Atlantic populations. A stepwise Linear Discriminant Analysis of the individual fish examined showed a separation among three groups: one including fish from the Mediterranean Sea (CTS, STS, and IOS); one consisting of fish from the Central South (CS), Eastern Tropical (ET), and Equatorial (TEQ) Atlantic; and a third comprising the fish sampled from the North-West Atlantic (NW); the CN Atlantic sample was more similar to the first group rather than to the other Atlantic ones. The nematodes Hysterothylacium petteri and Anisakis pegreffii were the species that contributed most to the characterization of the Mediterranean swordfish samples with respect to these Atlantic ones. Anisakis brevispiculata, A. physeteris, A. paggiae, Anisakis sp. 2, Hysterothylacium incurvum, Hepatoxylon trichiuri, Sphyriocephalus viridis, and their high infection levels were associated with the swordfish from the Central and the Southern Atlantic areas. Finally, H. corrugatum, A. simplex (s.s.), Rhadinorhynchus pristis, and Bolbosoma vasculosum were related to the fish from the North-West (NW) Atlantic area. These results indicate that some parasites, particularly Anisakis spp. larvae identified by genetic markers, could be used as “biological tags” and support the existence of a Mediterranean swordfish stock. PMID:25057787

Response of seabirds to fluctuations in forage fish density

USGS Publications Warehouse

Piatt, John F.

2002-01-01

Following the Exxon Valdez Oil Spill (EVOS), one concern was that prevailing ecological conditions in the Gulf of Alaska (GOA) would not favor recovery of damaged seabird populations. To address this issue, we examined relationships between oceanography, forage fish and seabirds near three seabird colonies in lower Cook Inlet (LCI) in 1995-1999 (some colony work continued until 2001). Upwelling of cold, nutrient-rich GOA waters at the entrance to the shallow LCI estuary supports a high density of juvenile pollock, sand lance, and capelin; which in turn are exploited by high densities of breeding seabirds (murres, kittiwakes, puffins, etc.) on the east side of LCI. Waters on the west side of LCI are oceanographically distinct (warmer, less saline, outflowing), and much less productive for forage fish and seabirds. Patterns of seabird foraging behavior, productivity and population change reflected patterns of forage fish abundance and distribution, which in turn depended on local oceanography. Most seabird parameters varied with forage fish density in a non-linear (e.g., sigmoidal, exponential) fashion, and in some areas and years, productivity was limited by food availability.  Current and projected ecological conditions favor recovery of seabirds from the EVOS at some colonies. In 14 chapters, this report summarizes data and compiles it into 247 tables, figures and appendices. Chapter 14 provides a thorough synthesis of overall project findings. Final analyses and interpretations of data will be published later in peer-reviewed journals (in addition to 61 articles already completed).

Techniques for Monitoring Razorback Sucker in the Lower Colorado River, Hoover to Parker Dams, 2006-2007, Final Report

USGS Publications Warehouse

Mueller, Gordon A.; Wydoski, Richard; Best, Eric; Hiebert, Steve; Lantow, Jeff; Santee, Mark; Goettlicher, Bill; Millosovich, Joe

2008-01-01

Trammel netting is generally the accepted method of monitoring razorback sucker in reservoirs, but this method is ineffective for monitoring this fish in rivers. Trammel nets set in the current become fouled with debris, and nets set in backwaters capture high numbers of nontarget species. Nontargeted fish composed 97 percent of fish captured in previous studies (1999-2005). In 2005, discovery of a large spawning aggregation of razorback sucker in midchannel near Needles, Calif., prompted the development of more effective methods to monitor this and possibly other riverine fish populations. This study examined the effectiveness of four methods of monitoring razorback sucker in a riverine environment. Hoop netting, electrofishing, boat surveys, and aerial photography were evaluated in terms of data accuracy, costs, stress on targeted fish, and effect on nontargeted fish as compared with trammel netting. Trammel netting in the riverine portion of the Colorado River downstream of Davis Dam, Arizona-Nevada yielded an average of 43 razorback suckers a year (1999 to 2005). Capture rates averaged 0.5 razorback suckers per staff day effort, at a cost exceeding $1,100 per fish. Population estimates calculated for 2003-2005 were 3,570 (95 percent confidence limits [CL] = 1,306i??i??i??-8,925), 1,768 (CL = 878-3,867) and 1,652 (CL = 706-5,164); wide confidence ranges reflect the small sample size. By-catch associated with trammel netting included common carp, game fish and, occasionally, shorebirds, waterfowl, and muskrats. Hoop nets were prone to downstream drift owing to design and anchoring problems aggravated by hydropower ramping. Tests were dropped after the 2006 field season and replaced with electrofishing. Electrofishing at night during low flow and when spawning razorback suckers moved to the shoreline proved extremely effective. In 2006 and 2007, 263 and 299 (respectively) razorback suckers were taken. Capture rates averaged 8.3 razorback suckers per staff day at a cost of $62 per fish. The adult population was estimated at 1,196 (925-1,546) fish. Compared with trammel netting, confidence limits narrowed substantially, from +or- 500 percent to +or- 30 percent, reflecting more precise estimates. By-catch was limited to two common carp. No recreational game fish, waterfowl, or mammals were captured or handled during use of electrofishing. Aerial photography (2006 and 2007) suggested an annual average of 580 fish detected on imagery. Identification of species was not possible; carp commonly have been mistaken for razorback sucker. Field verification determined that the proportion of razorback suckers to other fish was 3:1. On that basis, we estimated 435 razorback suckers were photographed, which equals 8.4 razorback suckers per staff day at a cost of $78 per fish. The data did not lend itself to population estimates. Fish were more easily identified from boats, where their lateral rather than their dorsal aspect is visible. On average, 888 razorback suckers were positively identified each year. Observation rates averaged 29.6 razorback suckers per staff day at a cost less than $18 per fish observed. Sucker densities averaged 20.5 and 9.6 fish/hectare which equated to an average spawning population at Needles, Calif., of 2,520 in 2006 and 1152 in 2007. The lower 2007 estimate reflected a refinement in sampling approach which removed a sampling bias. Electrofishing and boat surveys were more cost effective than other methods tested, and they provided more accurate information without the by-catch associated with trammel netting. However, they provided different types of data. Handling fish may be necessary for research purposes but unnecessary for general trend analysis. Electrofishing was extremely effective but can harm fish if not used with caution. Unnecessary electrofishing increases the likelihood of spinal damage and possible damage to eggs and potential young, and it may alter spawning behavior or duration. B

78 FR 39708 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Final Results of Antidumping...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-02

... From the Socialist Republic of Vietnam: Final Results of Antidumping Duty New Shipper Reviews; 2011... frozen fish fillets (``frozen fish fillets'') from the Socialist Republic of Vietnam (``Vietnam'').\\1...'' section of this notice. \\1\\ See Certain Frozen Fish Fillets From the Socialist Republic of Vietnam...

Levels of persistent contaminants in relation to fish consumption among older male anglers in Wisconsin.

PubMed

Christensen, Krista Y; Thompson, Brooke A; Werner, Mark; Malecki, Kristen; Imm, Pamela; Anderson, Henry A

2016-03-01

Fish are an important source of nutrients which may reduce risk of adverse health outcomes such as cardiovascular disease; however, fish may also contain significant amounts of environmental pollutants such as mercury, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and perfluorinated compounds (PFCs, also called perfluoroalkyl compounds), which confer increased risk for adverse health effects. The Wisconsin Departments of Health Services and Natural Resources developed a survey instrument, along with a strategy to collect human biological samples to assess the risks and benefits associated with long-term fish consumption among older male anglers in Wisconsin. The target population was men aged 50 years and older, who fish Wisconsin waters and live in the state of Wisconsin. Participants provided blood and hair samples and completed a detailed (paper) questionnaire, which included questions on basic demographics, health status, location of catch and species of fish caught/eaten, consumption of locally caught and commercially purchased fish, and awareness and source of information for local and statewide consumption guidelines. Biological samples were used to assess levels of PCBs, PBDEs, PFCs (blood), and mercury (hair and blood). Quantile regression analysis was used to investigate the associations between biomarker levels and self-reported consumption of fish from the Great Lakes and other areas of concern, other locally caught fish, and commercially purchased fish (meals per year). Respondents had a median age of 60.5 (interquartile range: 56, 67) years. The median fish consumption was 54.5 meals per year, with most fish meals coming from locally-caught fish. Participants had somewhat higher mercury levels compared with the US general population, while levels of other contaminants were similar or lower. Multivariate regression models showed that consumption of fish from the Great Lakes and areas of concern was associated with higher levels of each of the contaminants with the exception of PBDEs, as was consumption of locally caught fish from other water bodies. All commercial fish consumption was also associated with both hair and blood mercury. When looking at specific PCB, PBDE and PFC analytes, consumption of fish from the Great Lakes and areas of concern was associated with higher levels of each of the individual PCB congeners examined, as well as higher levels of all of the PFCs examined, with the exception of PFHxS. Among the PFCs, locally caught fish from other water bodies was also associated with higher levels of each of the congeners examined except PFHxS. Finally, all commercial fish was associated with higher levels of PFHxS. Published by Elsevier GmbH.

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.

Steelhead Supplementation Studies; Steelhead Supplementation in Idaho Rivers, Annual Report 2002.

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

Byrne, Alan

The Steelhead Supplementation Study (SSS) has two broad objectives: (1) investigate the feasibility of supplementing depressed wild and natural steelhead populations using hatchery populations, and (2) describe the basic life history and genetic characteristics of wild and natural steelhead populations in the Salmon and Clearwater Basins. Idaho Department of Fish and Game (IDFG) personnel stocked adult steelhead from Sawtooth Fish Hatchery into Frenchman and Beaver creeks and estimated the number of age-1 parr produced from the outplants since 1993. On May 2, 2002, both Beaver and Frenchman creeks were stocked with hatchery adult steelhead. A SSS crew snorkeled the creeksmore » in August 2002 to estimate the abundance of age-1 parr from brood year (BY) 2001. I estimated that the yield of age-1 parr per female stocked in 2001 was 7.3 and 6.7 in Beaver and Frenchman creeks, respectively. SSS crews stocked Dworshak hatchery stock fingerlings and smolts from 1993 to 1999 in the Red River drainage to assess which life stage produces more progeny when the adults return to spawn. In 2002, Clearwater Fish Hatchery personnel operated the Red River weir to trap adults that returned from these stockings. Twelve PIT-tagged adults from the smolt releases and one PIT-tagged adult from fingerling releases were detected during their migration up the mainstem Columbia and Snake rivers, but none from either group were caught at the weir. The primary focus of the study has been monitoring and collecting life history information from wild steelhead populations. An adult weir has been operated annually since 1992 in Fish Creek, a tributary of the Lochsa River. The weir was damaged by a rain-on-snow event in April 2002 and although the weir remained intact, some adults were able to swim undetected through the weir. Despite damage to the weir, trap tenders captured 167 adult steelhead, the most fish since 1993. The maximum likelihood estimate of adult steelhead escapement was 242. A screw trap has been operated annually in Fish Creek since 1994 to estimate the number of emigrating parr and smolts. I estimated that 18,687 juvenile steelhead emigrated from Fish Creek in 2002, the lowest number of migrants since 1998. SSS crews snorkeled three streams in the Selway River drainage and 10 streams in the Lochsa River drainage to estimate juvenile steelhead densities. The densities of age-1 steelhead parr declined in all streams compared to the densities observed in 2001. The age-1 densities in Fish Creek and Gedney Creek were the lowest observed since this project began monitoring those populations in 1994. The SSS crews and other cooperators tagged more than 12,000 juvenile steelhead with passive integrated transponder (PIT) tags in 2002. In 2002, technicians mounted and aged steelhead scales that were collected from 1998 to 2001. A consensus was reached among technicians for age of steelhead juveniles from Fish Creek. Scales that were collected in other streams were aged by at least one reader; however, before a final age is assigned to these fish, the age needs to be verified by another reader and any age differences among readers resolved. Dr. Jennifer Nielsen, at the U.S. Geological Survey Alaska Biological Science Center, Anchorage continued the microsatellite analysis of the steelhead tissue samples that were collected from Idaho streams in 2000. Two thousand eighteen samples from 40 populations were analyzed. The analysis of the remaining 39 populations is continuing.« less

Designation of a neotype for brook trout, Salvelinus fontinalis

USGS Publications Warehouse

Stauffer, Jay R; King, Timothy L.

2015-01-01

The taxonomic status of Salvelinus fontinalis (Mitchill) is problematic. Difficulties in comparison of populations are exacerbated by the lack of type material. Here we designate a neotype from Connetquot River, Long Island, New York. We provide genetic and morphological data for the neotype, conspecifics, and other populations (Swan Creek, Nissequogue Creek) from Long Island, New York. We demonstrate, using molecular markers, that the population from Connetquot River most likely has not been influenced by the major broodstock strains utilized in the Northeast for supplemental and restorative stocking programs. We distinguish the above populations morphologically from lower interior basin populations, represented by fishes from the Pigeon-French Broad drainage, North Carolina and Tennessee. Finally, we position populations from Long Island, New York, within six distinct lineages of S. fontinalis.

Fishes and aquatic habitats of the Orinoco River Basin: diversity and conservation.

PubMed

Lasso, C A; Machado-Allison, A; Taphorn, D C

2016-07-01

About 1000 freshwater fishes have been found so far in the Orinoco River Basin of Venezuela and Colombia. This high ichthyological diversity reflects the wide range of landscapes and aquatic ecosystems included in the basin. Mountain streams descend from the high Andes to become rapid-flowing foothill rivers that burst out upon vast savannah flatlands where they slowly make their way to the sea. These white-water rivers are heavily laden with sediments from the geologically young Andes. Because their sediment deposits have formed the richest soils of the basin, they have attracted the highest density of human populations, along with the greatest levels of deforestation, wildfires, agricultural biocides and fertilizers, sewage and all the other impacts associated with urban centres, agriculture and cattle ranching. In the southern portion of the basin, human populations are much smaller, where often the only inhabitants are indigenous peoples. The ancient rocks and sands of the Guiana Shield yield clear and black water streams of very different quality. Here, sediment loads are miniscule, pH is very acid and fish biomass is only a fraction of that observed in the rich Andean tributaries to the north. For each region of the basin, the current state of knowledge about fish diversity is assessed, fish sampling density evaluated, the presence of endemic species and economically important species (for human consumption or ornamental purposes) described and gaps in knowledge are pointed out. Current trends in the fishery for human consumption are analysed, noting that stocks of many species are in steep decline, and that current fishing practices are not sustainable. Finally, the major impacts and threats faced by the fishes and aquatic ecosystems of the Orinoco River Basin are summarized, and the creation of bi-national commissions to promote standardized fishing laws in both countries is recommended. © 2016 The Fisheries Society of the British Isles.

Integrated assessment of infant exposure to persistent organic pollutants and mercury via dietary intake in a central western Mediterranean site (Menorca Island).

PubMed

Junqué, Eva; Garí, Mercè; Arce, Anna; Torrent, Maties; Sunyer, Jordi; Grimalt, Joan O

2017-07-01

In this research the levels of organochlorine compounds (OCs) and mercury (Hg) in several food items from Menorca Island were presented. The dietary exposure assessment was performed in children population from the island. Finally, body burden of OCs and Hg in these infants were associated with their dietary intakes of the selected food items. The dietary exposure to persistent pollutants by children population from Menorca Island was assessed. The concentrations of 11 organochlorine pesticides, 6 polychlorinated biphenils (PCBs) and 1 inorganic toxic element, Hg, were determined in 46 food samples that included fish, shellfish, meat, fruit, vegetables, cheese and eggs, which were acquired in local markets and department stores in the Menorca Island. The most contaminated food items were fish and shellfish, followed by meat and cheese products. OC levels were similar or lower than in other previous studies. However, 66% of the analysed fish and shellfish species for Hg exceeded the human consumption safety limits according to the European Union Legislation. Pollutant data from food was combined with the pattern of consumption of these foodstuffs in order to calculate the estimated daily intake (EDI) of these contaminants. According to our results, fish and fruit were the main sources of OCs to the EDIs (contributing to 37% and 29%, respectively) while fish and shellfish were the main sources of Hg (76% and 17%). The estimated EDIs of OCs were well below to the reported FAO/WHO Tolerable Intakes. However, estimated weekly intake of Hg would exceed the Provisional Tolerable Weekly Intake indicated by EFSA in the case that the only fish and seafood source would be from the central western Mediterranean. Direct associations between fish/shellfish consumption and hair concentrations of Hg and fish and meat consumption and 4,4'-DDT concentrations in venous serum in the Menorcan children were observed. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

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.

Natural bounds on herbivorous coral reef fishes.

PubMed

Heenan, Adel; Hoey, Andrew S; Williams, Gareth J; Williams, Ivor D

2016-11-30

Humans are an increasingly dominant driver of Earth's biological communities, but differentiating human impacts from natural drivers of ecosystem state is crucial. Herbivorous fish play a key role in maintaining coral dominance on coral reefs, and are widely affected by human activities, principally fishing. We assess the relative importance of human and biophysical (habitat and oceanographic) drivers on the biomass of five herbivorous functional groups among 33 islands in the central and western Pacific Ocean. Human impacts were clear for some, but not all, herbivore groups. Biomass of browsers, large excavators, and of all herbivores combined declined rapidly with increasing human population density, whereas grazers, scrapers, and detritivores displayed no relationship. Sea-surface temperature had significant but opposing effects on the biomass of detritivores (positive) and browsers (negative). Similarly, the biomass of scrapers, grazers, and detritivores correlated with habitat structural complexity; however, relationships were group specific. Finally, the biomass of browsers and large excavators was related to island geomorphology, both peaking on low-lying islands and atolls. The substantial variability in herbivore populations explained by natural biophysical drivers highlights the need for locally appropriate management targets on coral reefs. © 2016 The Authors.

Convergent evolution of reduced energy demands in extremophile fish

PubMed Central

Arias-Rodriguez, Lenin; Tobler, Michael

2017-01-01

Convergent evolution in organismal function can arise from nonconvergent changes in traits that contribute to that function. Theory predicts that low resource availability and high maintenance costs in extreme environments select for reductions in organismal energy demands, which could be attained through modifications of body size or metabolic rate. We tested for convergence in energy demands and underlying traits by investigating livebearing fish (genus Poecilia) that have repeatedly colonized toxic, hydrogen sulphide-rich springs. We quantified variation in body size and routine metabolism across replicated sulphidic and non-sulphidic populations in nature, modelled total organismal energy demands, and conducted a common-garden experiment to test whether population differences had a genetic basis. Sulphidic populations generally exhibited smaller body sizes and lower routine metabolic rates compared to non-sulphidic populations, which together caused significant reductions in total organismal energy demands in extremophile populations. Although both mechanisms contributed to variation in organismal energy demands, variance partitioning indicated reductions of body size overall had a greater effect than reductions of routine metabolism. Finally, population differences in routine metabolism documented in natural populations were maintained in common-garden reared individuals, indicating evolved differences. In combination with other studies, these results suggest that reductions in energy demands may represent a common theme in adaptation to physiochemical stressors. Selection for reduced energy demand may particularly affect body size, which has implications for life history evolution in extreme environments. PMID:29077740

Fishes in a changing world: learning from the past to promote sustainability of fish populations.

PubMed

Gordon, T A C; Harding, H R; Clever, F K; Davidson, I K; Davison, W; Montgomery, D W; Weatherhead, R C; Windsor, F M; Armstrong, J D; Bardonnet, A; Bergman, E; Britton, J R; Côté, I M; D'agostino, D; Greenberg, L A; Harborne, A R; Kahilainen, K K; Metcalfe, N B; Mills, S C; Milner, N J; Mittermayer, F H; Montorio, L; Nedelec, S L; Prokkola, J M; Rutterford, L A; Salvanes, A G V; Simpson, S D; Vainikka, A; Pinnegar, J K; Santos, E M

2018-03-01

Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important challenges raised by these issues have been recognized and have led to considerable advances over past decades in managing and mitigating threats to fishes worldwide. In this review, we identify the major threats faced by fish populations alongside recent advances that are helping to address these issues. There are very significant efforts worldwide directed towards ensuring a sustainable future for the world's fishes and fisheries and those who rely on them. Although considerable challenges remain, by drawing attention to successful mitigation of threats to fish and fisheries we hope to provide the encouragement and direction that will allow these challenges to be overcome in the future. © 2018 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of The Fisheries Society of the British Isles.

San Francisco Estuary Striped Bass Migration History Determined by Electron-microprobe Analysis of Otolith Sr/Ca Ratio

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

Ostrach, D J; Phillis, C C; Weber, P K

2004-09-17

Habitat use has been shown to be an important factor in the bioaccumulation of contaminants in striped bass. This study examines migration in striped bass as part of a larger study investigating bioaccumulation and maternal transfer of xenobiotics to progeny in the San Francisco Estuary system. Habitat use, residence time and spawning migration over the life of females (n = 23) was studied. Female striped bass were collected between Knights Landing and Colusa on the Sacramento River during the spawning runs of 1999 and 2001. Otoliths were removed, processed and aged via otolith microstructure. Subsequently, otoliths were analyzed for strontium/calciummore » (Sr/Ca) ratio using an electron-microprobe to measure salinity exposure and to distinguish freshwater, estuary, and marine habitat use. Salinity exposure during the last year before capture was examined more closely for comparison of habitat use by the maternal parent to contaminant burden transferred to progeny. Results were selectively confirmed by ion microprobe analyses for habitat use. The Sr/Ca data demonstrate a wide range of migratory patterns. Age of initial ocean entry differs among individuals before returning to freshwater, presumably to spawn. Some fish reside in freshwater year-round, while others return to more saline habitats and make periodic migrations to freshwater. Frequency of habitat shifts and residence times differs among fish, as well as over the lifetime of individual fish. While at least one fish spent its final year in freshwater, the majority of spawning fish spent their final year in elevated salinity. However, not all fish migrated to freshwater to spawn in the previous year. Results from this investigation concerning migration history in striped bass can be combined with contaminant and histological developmental analyses to better understand the bioaccumulation of contaminants and the subsequent effects they and habitat use have on fish populations in the San Francisco Estuary system.« less

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.

Fundamental insights into ontogenetic growth from theory and fish.

PubMed

Sibly, Richard M; Baker, Joanna; Grady, John M; Luna, Susan M; Kodric-Brown, Astrid; Venditti, Chris; Brown, James H

2015-11-10

The fundamental features of growth may be universal, because growth trajectories of most animals are very similar, but a unified mechanistic theory of growth remains elusive. Still needed is a synthetic explanation for how and why growth rates vary as body size changes, both within individuals over their ontogeny and between populations and species over their evolution. Here, we use Bertalanffy growth equations to characterize growth of ray-finned fishes in terms of two parameters, the growth rate coefficient, K, and final body mass, m∞. We derive two alternative empirically testable hypotheses and test them by analyzing data from FishBase. Across 576 species, which vary in size at maturity by almost nine orders of magnitude, K scaled as [Formula: see text]. This supports our first hypothesis that growth rate scales as [Formula: see text] as predicted by metabolic scaling theory; it implies that species that grow to larger mature sizes grow faster as juveniles. Within fish species, however, K scaled as [Formula: see text]. This supports our second hypothesis, which predicts that growth rate scales as [Formula: see text] when all juveniles grow at the same rate. The unexpected disparity between across- and within-species scaling challenges existing theoretical interpretations. We suggest that the similar ontogenetic programs of closely related populations constrain growth to [Formula: see text] scaling, but as species diverge over evolutionary time they evolve the near-optimal [Formula: see text] scaling predicted by metabolic scaling theory. Our findings have important practical implications because fish supply essential protein in human diets, and sustainable yields from wild harvests and aquaculture depend on growth rates.

Spatial structuring within a reservoir fish population: implications for management

USGS Publications Warehouse

Stewart, David R.; Long, James M.; Shoup, Daniel E.

2014-01-01

Spatial structuring in reservoir fish populations can exist because of environmental gradients, species-specific behaviour, or even localised fishing effort. The present study investigated whether white crappie exhibited evidence of improved population structure where the northern more productive half of a lake is closed to fishing to provide waterfowl hunting opportunities. Population response to angling was modelled for each substock of white crappie (north (protected) and south (unprotected) areas), the entire lake (single-stock model) and by combining simulations of the two independent substock models (additive model). White crappie in the protected area were more abundant, consisting of larger, older individuals, and exhibited a lower total annual mortality rate than in the unprotected area. Population modelling found that fishing mortality rates between 0.1 and 0.3 resulted in sustainable populations (spawning potential ratios (SPR) >0.30). The population in the unprotected area appeared to be more resilient (SPR > 0.30) at the higher fishing intensities (0.35–0.55). Considered additively, the whole-lake fishery appeared more resilient than when modelled as a single-panmictic stock. These results provided evidence of spatial structuring in reservoir fish populations, and we recommend model assessments used to guide management decisions should consider those spatial differences in other populations where they exist.

Capturing ecology in modeling approaches applied to environmental risk assessment of endocrine active chemicals in fish.

PubMed

Mintram, Kate S; Brown, A Ross; Maynard, Samuel K; Thorbek, Pernille; Tyler, Charles R

2018-02-01

Endocrine active chemicals (EACs) are widespread in freshwater environments and both laboratory and field based studies have shown reproductive effects in fish at environmentally relevant exposures. Environmental risk assessment (ERA) seeks to protect wildlife populations and prospective assessments rely on extrapolation from individual-level effects established for laboratory fish species to populations of wild fish using arbitrary safety factors. Population susceptibility to chemical effects, however, depends on exposure risk, physiological susceptibility, and population resilience, each of which can differ widely between fish species. Population models have significant potential to address these shortfalls and to include individual variability relating to life-history traits, demographic and density-dependent vital rates, and behaviors which arise from inter-organism and organism-environment interactions. Confidence in population models has recently resulted in the EU Commission stating that results derived from reliable models may be considered when assessing the relevance of adverse effects of EACs at the population level. This review critically assesses the potential risks posed by EACs for fish populations, considers the ecological factors influencing these risks and explores the benefits and challenges of applying population modeling (including individual-based modeling) in ERA for EACs in fish. We conclude that population modeling offers a way forward for incorporating greater environmental relevance in assessing the risks of EACs for fishes and for identifying key risk factors through sensitivity analysis. Individual-based models (IBMs) allow for the incorporation of physiological and behavioral endpoints relevant to EAC exposure effects, thus capturing both direct and indirect population-level effects.

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.

Respondent driven sampling in a biomonitoring study of refugees from Burma in Buffalo, New York who eat Great Lakes fish.

PubMed

Liu, Ming; McCann, Molly; Lewis-Michl, Elizabeth; Hwang, Syni-An

2018-06-01

Refugees from Burma who consume fish caught from local waterbodies have increased risk of exposure to environmental contaminants. We used respondent driven sampling (RDS) to sample this hard-to-reach population for the first Biomonitoring of Great Lakes Populations program. In the current study, we examined the interview data and assessed the effectiveness of RDS to sample the unique population. In 2013, we used RDS to sample 205 Burmese refugees and immigrants residing in Buffalo, New York who consumed fish caught from Great Lakes waters. RDS-adjusted population estimates of sociodemographic characteristics, residential history, fish consumption related behaviors, and awareness of fish advisories were obtained. We also examined sample homophily and equilibrium to assess how well the RDS assumptions were met in the study. Our sample was diverse with respect to sex, age, years residing in Buffalo, years lived in a refugee camp, education, employment, and fish consumption behaviors, and each of these variables reached equilibrium by the end of recruitment. Burmese refugees in Buffalo consumed Great Lakes fish throughout the year; a majority of them consumed the fish more than two times per week during summer, and about one third ate local fish more than once per week in winter. An estimated 60% of Burmese refugees in Buffalo had heard about local fish advisories. RDS has the potential to be an effective methodology for sampling refugees and immigrants in conducting biomonitoring and environmental exposure assessment. Due to high fish consumption and limited awareness and knowledge of fish advisories, some refugee and immigrant populations are more susceptible to environmental contaminants. Increased awareness on local fish advisories is needed among these populations. Published by Elsevier GmbH.

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 ...

Assessment of the Fishery Improvement Opportunities on the Pend Oreille River: Recommendations for Fisheries Enhancement: Final Report.

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

Ashe, Becky L.; Scholz, Allan T.

1992-03-01

This report recommends resident fish substitution projects to partially replace anadromous fish losses caused by construction of Grand Coulee and Chief Joseph Dams. These recommendations involve enhancing the resident fishery in the Pend Oreille River as a substitute for anadromous fish losses. In developing these recommendations we have intentionally attempted to minimize the impact upon the hydroelectric system and anadromous fish recovery plans. In this report we are recommending that the Northwest Power Planning Council direct Bonneville Power Administration to fund the proposed enhancement measures as resident fish substitution projects under the NPPC's Columbia Basin Fish and Wildlife Program. Themore » Pend Oreille River, located in northeast Washington, was historically a free flowing river which supported anadromous steelhead trout and chinook salmon, and large resident cutthroat trout and bull trout. In 1939, Grand Coulee Dam eliminated the anadromous species from the river. In 1955, Box Canyon Dam was constructed, inundating resident trout habitat in the river and creating many back water and slough areas. By the late 1950's the fishery in the reservoir had changed from a quality trout fishery to a warm water fishery, supporting largemouth bass, yellow perch and rough fish (tenth, suckers, squawfish). The object of this study was to examine the existing fishery, identify fishery improvement opportunities and recommend fishery enhancement projects. Three years of baseline data were collected from the Box Canyon portion of the Pend Oreille River to assess population dynamics, growth rates, feeding habits, behavior patterns and factors limiting the fishery. Fishery improvement opportunities were identified based on the results of these data. Relative abundance surveys in the reservoir resulted in the capture of 47,415 fish during the study. The most abundant species in the reservoir were yellow perch, composing 44% of the fish captured. The perch population in the river is stunted and therefore not popular with anglers. Pumpkinseed composed 16% of the total catch, followed by tenth (9%), largemouth bass (8%), mountain whitefish (6%), largescale sucker (5%), northern squawfish (4%) and longnose sucker (3%).« less

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.

Editorial

PubMed

Lewis

1998-12-01

In this issue of the Journal of Helminthology I have much pleasure in including a selection of papers drawn from two workshops, one on 'Nematode Population Genetics' and another on the 'Ecology of Fish Parasites' held in April 1998 at Exeter during the Spring Meeting of the British Society for Parasitology (BSP).The aim of the workshop on 'Nematode Population Genetics' convened by Dr Mark Viney, University of Edinburgh, is to review the current state of knowledge of this topic and to consider future research priorities. Following Mark Viney's overview, Michael Blouin, Oregon State University, Corvallis, USA, considers the effects of parasite life histories on mitochondrial DNA diversity in nematodes. Marleen Roos et al., Institute for Animal Science and Health and the University of Utrecht, The Netherlands, then review polymorphic DNA markers in the genome of parasitic nematodes whereas in the fourth and final paper of this series Alison Galvani and Sunetra Gupta, University of Oxford, consider the effects of mating probability on the population genetics of nematodes.Two papers from the workshop on the 'Ecology of Fish Parasites', convened by Professor Clive Kennedy, University of Exeter, focus on the community ecology of helminths in fish and include a study by Clive Kennedy et al., University of Exeter and University of Rome on the 'Composition and diversity of helminth communities in eels in the River Tiber: long term changes and comparison with insular Europe'. This is followed by an invited paper by William Font, Southeastern Louisiana University, USA on 'Parasites in paradise: patterns of helminth distribution in Hawaiian stream fishes'.I wish to express my grateful thanks to Mark Viney and Clive Kennedy for their assistance in the publication of these papers for this special issue.

Predation by Resident Fish on Juvenile Salmonids in John Day Reservoir: Final Report, 1983-1986: Volume 1, Final Report of Research.

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

Poe, Thomas P.; Rieman, Bruce E.

1988-07-01

In 1982 the NPPC included in its Fish and Wildlife Program a measure that called for studies ''... to investigate juvenile salmon and steelhead losses to predators while these fish are migrating through Columbia and Snake River reservoirs.'' In the same year the Bonneville Power Administration (BPA) funded ODFW and FWS to conduct collaborative studies to estimate the number of juvenile salmonids lost to predators in John Day Reservoir. Also included as study objectives were: (1) a description of the importance of predation losses relative to mortality at the dam and total reservoir mortality; (2) a description of how predationmore » losses might vary (spatially and temporally); and (3) recommendations of measures to control predation on smolts. We studied four species of predator: northern squawfish, walleye, smallmouth bass, and channel catfish. We selected John Day Reservoir as the study site because the following factors led us to believe if predation was a problem in any reservoir, it would be most obvious there because: (1) the reservoir is an important subyearling chinook rearing area; (2) passage and residualism of juvenile salmonids were considered a problem there; and (3) substantial populations of predators were known to reside in the reservoir. Individual reports were processed separately for the data base.« less

Thermal preference predicts animal personality in Nile tilapia Oreochromis niloticus.

PubMed

Cerqueira, Marco; Rey, Sonia; Silva, Tome; Featherstone, Zoe; Crumlish, Margaret; MacKenzie, Simon

2016-09-01

Environmental temperature gradients provide habitat structure in which fish orientate and individual thermal choice may reflect an essential integrated response to the environment. The use of subtle thermal gradients likely impacts upon specific physiological and behavioural processes reflected as a suite of traits described by animal personality. In this study, we examine the relationship between thermal choice, animal personality and the impact of infection upon this interaction. We predicted that thermal choice in Nile tilapia Oreochromis niloticus reflects distinct personality traits and that under a challenge individuals exhibit differential thermal distribution. Nile tilapia were screened following two different protocols: 1) a suite of individual behavioural tests to screen for personality and 2) thermal choice in a custom-built tank with a thermal gradient (TCH tank) ranging from 21 to 33 °C. A first set of fish were screened for behaviour and then thermal preference, and a second set were tested in the opposite fashion: thermal then behaviour. The final thermal distribution of the fish after 48 h was assessed reflecting final thermal preferendum. Additionally, fish were then challenged using a bacterial Streptococcus iniae model infection to assess the behavioural fever response of proactive and reactive fish. Results showed that individuals with preference for higher temperatures were also classified as proactive with behavioural tests and reactive contemporaries chose significantly lower water temperatures. All groups exhibited behavioural fever recovering personality-specific thermal preferences after 5 days. Our results show that thermal preference can be used as a proxy to assess personality traits in Nile tilapia and it is a central factor to understand the adaptive meaning of animal personality within a population. Importantly, response to infection by expressing behavioural fever overrides personality-related thermal choice. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

Monola oil versus canola oil as a fish oil replacer in rainbow trout feeds: effects on growth, fatty acid metabolism and final eating quality.

PubMed

Turchini, G M; Moretti, V M; Hermon, K; Caprino, F; Busetto, M L; Bellagamba, F; Rankin, T; Keast, R S J; Francis, D S

2013-11-15

Monola oil, a high oleic acid canola cultivar, and canola oil were evaluated as replacers of fish oil at three levels of inclusion (60%, 75% and 90%) in rainbow trout diets. After a 27-week grow-out cycle, the diet-induced effects on growth, fatty acid metabolism and final eating quality were assessed. Overall, no effects were noted for growth, feed utilisation or fish biometry, and the fatty acid composition of fish fillets mirrored that of the diets. Dietary treatments affected fillet lipid oxidation (free malondialdehyde), pigmentation and flavour volatile compounds, but only minor effects on sensorial attributes were detected. Ultimately, both oils were demonstrated to possess, to differing extents, suitable qualities to adequately replace fish oil from the perspective of fish performance and final product quality. However, further research is required to alleviate on-going issues associated with the loss of health promoting attributes (n-3 long chain polyunsaturated fatty acids) of final farmed products. Copyright © 2013 Elsevier Ltd. All rights reserved.

Columbia River System Operation Review : Final Environmental Impact Statement, Appendix C: Anadromous Fish and Juvenile Fish Transportation.

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

Columbia River System Operation Review

1995-11-01

This Appendix C of the Final Environmental Impact Statement for the Columbia River System discusses impacts on andromous fish and juvenile fish transportation. The principal andromous fish in the Columbia basin include salmonid species (Chinook, coho, and sockeye salmon, and steelhead) and nonsalmoinid andromous species (sturgeon, lamprey, and shad). Major sections in this document include the following: background, scope and process; affected environment for salmon and steelhead, shaded, lamprey, sturgeon; study methods; description of alternatives: qualitative and quantitative findings.

Effects of hatchery fish density on emigration, growth, survival, and predation risk of natural steelhead parr in an experimental stream channel

USGS Publications Warehouse

Tatara, Christopher P.; Riley, Stephen C.; Berejikian, Barry A.

2011-01-01

Hatchery supplementation of steelhead Oncorhynchus mykiss raises concerns about the impacts on natural populations, including reduced growth and survival, displacement, and increased predation. The potential risks may be density dependent.We examined how hatchery stocking density and the opportunity to emigrate affect the responses of natural steelhead parr in an experimental stream channel and after 15 d found no density-dependent effects on growth, emigration, or survival at densities ranging from 1-6 hatchery parr/m2. The opportunity for steelhead parr to emigrate reduced predation by coastal cutthroat trout O. clarkii clarkii on both hatchery and natural steelhead parr. The cutthroat trout exhibited a type-I functional response (constant predation rate with increased prey density) for the hatchery and composite populations. In contrast, the predation rate on natural parr decreased as hatchery stocking density increased. Supplementation with hatchery parr at any experimental stocking density reduced the final natural parr density. This decline was explained by increased emigration fromthe supplemented groups. Natural parr had higher mean instantaneous growth rates than hatchery parr. The proportion of parr emigrating decreased as parr size increased over successive experimental trials. Smaller parr had lower survival and suffered higher predation. The final density of the composite population, a measure of supplementation effectiveness, increased with the hatchery steelhead stocking rate. Our results indicate that stocking larger hatchery parr (over 50 d postemergence) at densities within the carrying capacity would have low short-term impact on the growth, survival, and emigration of natural parr while increasing the density of the composite population; in addition, a stocking density greater than 3 fish/m2 might be a good starting point for the evaluation of parr stocking in natural streams.

75 FR 6058 - Federal Sport Fish Restoration; California Department of Fish and Game Fish Hatchery and Stocking...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-05

...] Federal Sport Fish Restoration; California Department of Fish and Game Fish Hatchery and Stocking Program...) announces the availability of the final EIR/EIS for the California Department of Fish and Game's (CDFG) Fish.... This legislation called for the newly formed California State Fish and Game Commission to establish...

The population structure and recent colonization history of Oregon threespine stickleback determined using RAD-seq

PubMed Central

Catchen, Julian; Bassham, Susan; Wilson, Taylor; Currey, Mark; O’Brien, Conor; Yeates, Quick; Cresko, William A.

2013-01-01

Understanding how genetic variation is partitioned across genomes within and among populations is a fundamental problem in ecological and evolutionary genetics. To address this problem we are studied the threespine stickleback fish, which has repeatedly undergone parallel phenotypic and genetic differentiation when oceanic fish have invaded freshwater habitats. While significant evolutionary genetic research has been performed using stickleback from geographic regions that have been de-glaciated in the last 20,000 years, less research has focused on freshwater populations that predate the last glacial maximum. We performed RAD-seq based population genomic analyses on stickleback from across Oregon, which was not glaciated during the last maximum. We sampled stickleback from coastal, Willamette Basin, and central Oregon sites, analyzed their genetic diversity using RAD-seq, performed STRUCTURE analyses, reconstructed their phylogeographic history, and tested the hypothesis of recent stickleback introduction into central Oregon, where incidence of this species was only recently documented. Our results showed a clear phylogeographic break between coastal and inland populations, with oceanic populations exhibiting the lowest levels of divergence from one another. Willamette Basin and central Oregon populations formed a clade of closely related populations, a finding consistent with a recent introduction of stickleback into central Oregon. Finally, genome wide analysis of genetic diversity (π) and correlations of alleles within individuals in subpopulations (FIS) supported a role for introgressive hybridization in coastal populations and a recent expansion in central Oregon. Our results exhibit the power of next generation sequencing genomic approaches such as RAD-seq to identify both historical population structure and recent colonization history. PMID:23718143

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...

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 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 ...

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...

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.

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.

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.

Fish population dynamics in a seasonally varying wetland

USGS Publications Warehouse

DeAngelis, Donald L.; Trexler, Joel C.; Cosner, Chris; Obaza, Adam; Jopp, Fred

2010-01-01

Small fishes in seasonally flooded environments such as the Everglades are capable of spreading into newly flooded areas and building up substantial biomass. Passive drift cannot account for the rapidity of observed population expansions. To test the reaction-diffusion mechanism for spread of the fish, we estimated their diffusion coefficient and applied a reaction-diffusion model. This mechanism was also too weak to account for the spatial dynamics. Two other hypotheses were tested through modeling. The first--the 'refuge mechanism--hypothesizes that small remnant populations of small fishes survive the dry season in small permanent bodies of water (refugia), sites where the water level is otherwise below the surface. The second mechanism, which we call the 'dynamic ideal free distribution mechanism' is that consumption by the fish creates a prey density gradient and that fish taxis along this gradient can lead to rapid population expansion in space. We examined the two alternatives and concluded that although refugia may play an important role in recolonization by the fish population during reflooding, only the second, taxis in the direction of the flooding front, seems capable of matching empirical observations. This study has important implications for management of wetlands, as fish biomass is an essential support of higher trophic levels.

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

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

Effective size of a wild salmonid population is greatly reduced by hatchery supplementation

PubMed Central

Christie, M R; Marine, M L; French, R A; Waples, R S; Blouin, M S

2012-01-01

Many declining and commercially important populations are supplemented with captive-born individuals that are intentionally released into the wild. These supplementation programs often create large numbers of offspring from relatively few breeding adults, which can have substantial population-level effects. We examined the genetic effects of supplementation on a wild population of steelhead (Oncorhynchus mykiss) from the Hood River, Oregon, by matching 12 run-years of hatchery steelhead back to their broodstock parents. We show that the effective number of breeders producing the hatchery fish (broodstock parents; Nb) was quite small (harmonic mean Nb=25 fish per brood-year vs 373 for wild fish), and was exacerbated by a high variance in broodstock reproductive success among individuals within years. The low Nb caused hatchery fish to have decreased allelic richness, increased average relatedness, more loci in linkage disequilibrium and substantial levels of genetic drift in comparison with their wild-born counterparts. We also documented a substantial Ryman–Laikre effect whereby the additional hatchery fish doubled the total number of adult fish on the spawning grounds each year, but cut the effective population size of the total population (wild and hatchery fish combined) by nearly two-thirds. We further demonstrate that the Ryman–Laikre effect is most severe in this population when (1) >10% of fish allowed onto spawning grounds are from hatcheries and (2) the hatchery fish have high reproductive success in the wild. These results emphasize the trade-offs that arise when supplementation programs attempt to balance disparate goals (increasing production while maintaining genetic diversity and fitness). PMID:22805657

Strong genetic divergence among populations of a marine fish with limited dispersal, Acanthochromis polyacanthus, within the Great Barrier Reef and the Coral Sea.

PubMed

Planes, S; Doherty, P J; Bernardi, G

2001-11-11

Acanthochromis polyacanthus is an unusual tropical marine damselfish that uniquely lacks pelagic larvae and has lost the capacity for broad-scale dispersal among coral reefs. On the modern Great Barrier Reef (GBR), three color morphs meet and hydridize at two zones of secondary contact. Allozyme electrophoreses revealed strong differences between morphs from the southern zone but few differences between morphs from the northern counterpart, thus suggesting different contact histories. We explore the phylogeography of Acanthochromis polyacanthus with mitochondrial cytochrome b region sequences (alignment of 565 positions) obtained from 126 individuals representing seven to 12 fish from 13 sites distributed over 12 reefs of the GBR and the Coral Sea. The samples revealed three major clades: (1) black fish collected from the southern GBR; (2) bicolored fish collected from the GBR and one reef (Osprey) from the northern Coral Sea; (3) black and white monomorphs collected from six reefs in the Coral Sea. All three clades were well supported (72-100%) by bootstrap analyses. Sequence divergences were very high between the major clades (mean = 7.6%) as well as within them (2.0-3.6%). Within clades, most reefs segregated as monophyletic assemblages. This was revealed both by phylogenetic analyses and AMOVAs that showed that 72-90% of the variance originated from differences among groups, whereas only 5-13% originated within populations. These patterns are discussed in relation to the known geological history of coral reefs of the GBR and the Coral Sea. Finally, we ask whether the monospecific status of Acanthochromis should be revisited because the sequence divergences found among our samples is substantially greater than those recorded among well-recognized species in other reef fishes.

Fundamental insights into ontogenetic growth from theory and fish

PubMed Central

Sibly, Richard M.; Baker, Joanna; Grady, John M.; Luna, Susan M.; Kodric-Brown, Astrid; Venditti, Chris; Brown, James H.

2015-01-01

The fundamental features of growth may be universal, because growth trajectories of most animals are very similar, but a unified mechanistic theory of growth remains elusive. Still needed is a synthetic explanation for how and why growth rates vary as body size changes, both within individuals over their ontogeny and between populations and species over their evolution. Here, we use Bertalanffy growth equations to characterize growth of ray-finned fishes in terms of two parameters, the growth rate coefficient, K, and final body mass, m∞. We derive two alternative empirically testable hypotheses and test them by analyzing data from FishBase. Across 576 species, which vary in size at maturity by almost nine orders of magnitude, K scaled as m∞−0.23. This supports our first hypothesis that growth rate scales as m∞−0.25 as predicted by metabolic scaling theory; it implies that species that grow to larger mature sizes grow faster as juveniles. Within fish species, however, K scaled as m∞−0.35. This supports our second hypothesis, which predicts that growth rate scales as m∞−0.33 when all juveniles grow at the same rate. The unexpected disparity between across- and within-species scaling challenges existing theoretical interpretations. We suggest that the similar ontogenetic programs of closely related populations constrain growth to m∞−0.33 scaling, but as species diverge over evolutionary time they evolve the near-optimal m∞−0.25 scaling predicted by metabolic scaling theory. Our findings have important practical implications because fish supply essential protein in human diets, and sustainable yields from wild harvests and aquaculture depend on growth rates. PMID:26508641

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.

An evaluation of the effects of conservation and fishery enhancement hatcheries on wild populations of salmon.

PubMed

Naish, Kerry A; Taylor, Joseph E; Levin, Phillip S; Quinn, Thomas P; Winton, James R; Huppert, Daniel; Hilborn, Ray

2007-01-01

The historical, political and scientific aspects of salmon hatchery programmes designed to enhance fishery production, or to recover endangered populations, are reviewed. We start by pointing out that the establishment of hatcheries has been a political response to societal demands for harvest and conservation; given this social context, we then critically examined the levels of activity, the biological risks, and the economic analysis associated with salmon hatchery programmes. A rigorous analysis of the impacts of hatchery programmes was hindered by the lack of standardized data on release sizes and survival rates at all ecological scales, and since hatchery programme objectives are rarely defined, it was also difficult to measure their effectiveness at meeting release objectives. Debates on the genetic effects of hatchery programmes on wild fish have been dominated by whether correct management practices can reduce negative outcomes, but we noted that there has been an absence of programmatic research approaches addressing this important issue. Competitive interactions between hatchery and wild fish were observed to be complex, but studies researching approaches to reduce these interactions at all ecological scales during the entire salmon life history have been rare, and thus are not typically considered in hatchery management. Harvesting of salmon released from fishery enhancement hatcheries likely impacts vulnerable wild populations; managers have responded to this problem by mass marking hatchery fish, so that fishing effort can be directed towards hatchery populations. However, we noted that the effectiveness of this approach is dependant on accurate marking and production of hatchery fish with high survival rates, and it is not yet clear whether selective fishing will prevent overharvest of wild populations. Finally, research demonstrating disease transmission from hatchery fish to wild populations was observed to be equivocal; evidence in this area has been constrained by the lack of effective approaches to studying the fate of pathogens in the wild. We then reviewed several approaches to studying the economic consequences of hatchery activities intended to inform the social decisions surrounding programmes, but recognized that placing monetary value on conservation efforts or on hatcheries that mitigate cultural groups' loss of historical harvest opportunities may complicate these analyses. We noted that economic issues have rarely been included in decision making on hatchery programmes. We end by identifying existing major knowledge gaps, which, if filled, could contribute towards a fuller understanding of the role that hatchery programmes could play in meeting divergent goals. However, we also recognized that many management recommendations arising from such research may involve trade-offs between different risks, and that decisions about these trade-offs must occur within a social context. Hatcheries have played an important role in sustaining some highly endangered populations, and it is possible that reform of practices will lead to an increase in the number of successful programmes. However, a serious appraisal of the role of hatcheries in meeting broader needs is urgently warranted and should take place at the scientific, but more effectively, at the societal level.

An evaluation of the effects of conservation and fishery enhancement hatcheries on wild populations of salmon

USGS Publications Warehouse

Naish, Kerry A.; Taylor, Joseph E.; Levin, Phillip S.; Quinn, Thomas P.; Winton, James R.; Huppert , Daniel; Hilborn , Ray

2007-01-01

The historical, political and scientific aspects of salmon hatchery programmes designed to enhance fishery production, or to recover endangered populations, are reviewed. We start by pointing out that the establishment of hatcheries has been a political response to societal demands for harvest and conservation; given this social context, we then critically examined the levels of activity, the biological risks, and the economic analysis associated with salmon hatchery programmes. A rigorous analysis of the impacts of hatchery programmes was hindered by the lack of standardized data on release sizes and survival rates at all ecological scales, and since hatchery programme objectives are rarely defined, it was also difficult to measure their effectiveness at meeting release objectives. Debates on the genetic effects of hatchery programmes on wild fish have been dominated by whether correct management practices can reduce negative outcomes, but we noted that there has been an absence of programmatic research approaches addressing this important issue. Competitive interactions between hatchery and wild fish were observed to be complex, but studies researching approaches to reduce these interactions at all ecological scales during the entire salmon life history have been rare, and thus are not typically considered in hatchery management. Harvesting of salmon released from fishery enhancement hatcheries likely impacts vulnerable wild populations; managers have responded to this problem by mass marking hatchery fish, so that fishing effort can be directed towards hatchery populations. However, we noted that the effectiveness of this approach is dependant on accurate marking and production of hatchery fish with high survival rates, and it is not yet clear whether selective fishing will prevent overharvest of wild populations. Finally, research demonstrating disease transmission from hatchery fish to wild populations was observed to be equivocal; evidence in this area has been constrained by the lack of effective approaches to studying the fate of pathogens in the wild. We then reviewed several approaches to studying the economic consequences of hatchery activities intended to inform the social decisions surrounding programmes, but recognized that placing monetary value on conservation efforts or on hatcheries that mitigate cultural groups’ loss of historical harvest opportunities may complicate these analyses. We noted that economic issues have rarely been included in decision making on hatchery programmes. We end by identifying existing major knowledge gaps, which, if filled, could contribute towards a fuller understanding of the role that hatchery programmes could play in meeting divergent goals. However, we also recognized that many management recommendations arising from such research may involve trade-offs between different risks, and that decisions about these trade-offs must occur within a social context. Hatcheries have played an important role in sustaining some highly endangered populations, and it is possible that reform of practices will lead to an increase in the number of successful programmes. However, a serious appraisal of the role of hatcheries in meeting broader needs is urgently warranted and should take place at the scientific, but more effectively, at the societal level.

77 FR 71041 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Southern...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-28

...We, the U.S. Fish and Wildlife Service, designate critical habitat for the southern Selkirk Mountains population of woodland caribou (Rangifer tarandus caribou) under the Endangered Species Act. In total, approximately 30,010 acres (12,145 hectares) is being designated as critical habitat. The critical habitat is located in Boundary County, Idaho, and Pend Oreille County, Washington. We are finalizing this action in compliance with our obligation under the Act and in compliance with a court-approved settlement agreement. The effect of this regulation is to conserve the habitat essential to the southern Selkirk Mountains population of woodland caribou.

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...

Biological Control Agents of Hydrilla Verticillata; Final Report on Surveys in East Africa, 1981-1984.

DTIC Science & Technology

1986-07-01

terminal buds, attributable to insect feeding, but no causative agent was found. Some stems had obviously been grazed by fish, probably Tilapia ziulii...dispersal of the phytophagous Tilapia zillii through much of the region may also have played a part in stressing the plant. However, it seems...in nutrients. Most have high populations of depauperate Tilapia and, possibly as a result, are seemingly devoid of sub- 4merged vegetation. Pistia was

The effects of chronological age and size on toxicity of zinc to juvenile brown trout.

PubMed

Diedrich, Daniel J; Sofield, Ruth M; Ranville, James F; Hoff, Dale J; Wall, V Dan; Brinkman, Stephen F

2015-07-01

A series of toxicity tests were conducted to investigate the role of chronological age on zinc tolerance in juvenile brown trout (Salmo trutta). Four different incubation temperatures were used to control the maturation of the juveniles before zinc exposures. These 96-h exposures used flow-through conditions and four chronological ages of fish with weights ranging from 0.148 to 1.432 g. Time-to-death (TTD) data were collected throughout the exposure along with the final mortality. The results indicate that chronological age does not play a predictable role in zinc tolerance for juvenile brown trout. However, a relationship between zinc tolerance and fish size was observed in all chronological age populations, which prompted us to conduct additional exploratory data analysis to quantify how much of an effect size had during this stage of development. The smallest fish (0.148-0.423 g) were shown to be less sensitive than the largest fish (0.639-1.432 g) with LC50 values of 868 and 354 µg Zn/L, respectively. The Kaplan-Meier product estimation method was used to determine survival functions from the TTD data and supports the LC50 results with a greater median TTD for smaller fish than larger juvenile fish. These results indicate that fish size or a related characteristic may be a significant determinant of susceptibility and should be considered in acute zinc toxicity tests with specific attention paid to the expected exposure scenario in the field.

[Fishery resource protection by artificial propagation in hydroelectric development: Lixianjiang River drainage in Yunnan as an example].

PubMed

Yang, Yong-Hong; Yang, Jun-Xing; Pan, Xiao-Fu; Zhou, Wei; Yang, Mei-Lin

2011-04-01

Hydroelectric developments can result in a number of negative environmental consequences. Conservation aquaculture is a branch of science derived from conservation and population recovery studies on endangered fishes. Here we discuss the impacts on fishes caused by hydropower projects in Lixianjiang, and evaluate effects and problems on the propagation of Parazacco spilurus, Hemibagrus pluriradiatus, Neolissochilus benasi and Semilabeo obscurus. A successful propagation project includes foraging ecology in fields, pond cultivation, juvenile fish raising, prevention and curing on fish disease, genetic management, artificial releasing and population monitoring. Artificial propagation is the practicable act on genetic intercommunication, preventing population deterioration for fishes in upper and lower reaches of the dam. For long-term planning, fish stocks are not suitable for many kind of fishes, but can prevent fishes from going extinct in the wild. Basic data collection on fish ecology, parent fish hunting, prevention on fish disease are the most important factors on artificial propagation. Strengthening the genetic management of stock population for keeping a higher genetic diversity can increase the success of stock enhancement. The works on Lixianjiang provide a new model for river fish protection. To make sure the complicated project works well, project plans, commission contracts, base line monitoring and techniques on artificial reproduction must be considered early. Last, fishery conservation should be considered alongside location development.

78 FR 6218 - Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; Reef Fish Fishery of the Gulf of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-30

...NMFS issues this final rule to implement management measures described in Amendment 38 to the Fishery Management Plan for the Reef Fish Resources of the Gulf of Mexico (FMP) prepared by the Gulf of Mexico (Gulf) Fishery Management Council (Council). This final rule modifies post-season accountability measures (AMs) that affect the recreational harvest of shallow-water grouper species (SWG), changes the trigger for recreational sector AMs for gag and red grouper, and revises the Gulf reef fish framework procedure. The intent of this final rule is to achieve optimum yield (OY) while ensuring the Gulf reef fish fishery resources are utilized efficiently.

Thermodynamic and Mechanic Consideration on the stability of Anti-symmetric Schaefer’s equation

NASA Astrophysics Data System (ADS)

Suriamihardja, D. A.; Amiruddin; Saaduddin

2018-03-01

Schaefer’s equation relates an interaction between population of fishes and the number of units of fishing effort. The population growth of fishes is reduced by the number of units of fishing effort, while the population growth of units of fishing effort depends on the existence of fishes. This paper aims to examine the stability of an anti-symmetric Schaefer’s equation through thermodynamic and mechanic procedure using a formula of entropy production near equilibrium which is recognized as Onsager’s relation. The results confirm that entropic approach (thermodynamics) and dissipative approach (mechanics) are usable to be applied as Lyapunov’s procedure in examining the stability of systems of differential equations.

78 FR 29323 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Amended Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-20

...The Department of Commerce (the ``Department'') is amending the final results of the eighth administrative review and aligned new shipper reviews on certain frozen fish fillets (``fish fillets'') from the Socialist Republic of Vietnam (``Vietnam'') to correct certain ministerial errors.\\1\\ The period of review (``POR'') is August 1, 2010, through July 31, 2011. ---------------------------------------------------------------------------

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

Behavioural syndromes in fishes: a review with implications for ecology and fisheries management.

PubMed

Conrad, J L; Weinersmith, K L; Brodin, T; Saltz, J B; Sih, A

2011-02-01

This review examines the contribution of research on fishes to the growing field of behavioural syndromes. Current knowledge of behavioural syndromes in fishes is reviewed with respect to five main axes of animal personality: (1) shyness-boldness, (2) exploration-avoidance, (3) activity, (4) aggressiveness and (5) sociability. Compared with other taxa, research on fishes has played a leading role in describing the shy-bold personality axis and has made innovative contributions to the study of the sociability dimension by incorporating social network theory. Fishes are virtually the only major taxon in which behavioural correlations have been compared between populations. This research has guided the field in examining how variation in selection regime may shape personality. Recent research on fishes has also made important strides in understanding genetic and neuroendocrine bases for behavioural syndromes using approaches involving artificial selection, genetic mapping, candidate gene and functional genomics. This work has illustrated consistent individual variation in highly complex neuroendocrine and gene expression pathways. In contrast, relatively little work on fishes has examined the ontogenetic stability of behavioural syndromes or their fitness consequences. Finally, adopting a behavioural syndrome framework in fisheries management issues including artificial propagation, habitat restoration and invasive species, may promote restoration success. Few studies, however, have examined the ecological relevance of behavioural syndromes in the field. Knowledge of how behavioural syndromes play out in the wild will be crucial to incorporating such a framework into management practices. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

Approximate sample sizes required to estimate length distributions

USGS Publications Warehouse

Miranda, L.E.

2007-01-01

The sample sizes required to estimate fish length were determined by bootstrapping from reference length distributions. Depending on population characteristics and species-specific maximum lengths, 1-cm length-frequency histograms required 375-1,200 fish to estimate within 10% with 80% confidence, 2.5-cm histograms required 150-425 fish, proportional stock density required 75-140 fish, and mean length required 75-160 fish. In general, smaller species, smaller populations, populations with higher mortality, and simpler length statistics required fewer samples. Indices that require low sample sizes may be suitable for monitoring population status, and when large changes in length are evident, additional sampling effort may be allocated to more precisely define length status with more informative estimators. ?? Copyright by the American Fisheries Society 2007.

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.

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.

Development of standard weight equations for Caribbean and Gulf of Mexico amphidromous fishes

USGS Publications Warehouse

Cooney, Patrick B.; Kwak, Thomas J.

2010-01-01

We collected and compiled length and weight information from four countries and one commonwealth to develop standard weight (Ws) equations for three amphidromous fish species native to the Caribbean and Gulf of Mexico regions: mountain mullet Agonostomus monticola (N = 9,768 individuals, 52 populations), river goby Awaous banana (N = 1,847 individuals, 62 populations), and bigmouth sleeper Gobiomorus dormitor (N = 2,983 individuals, 53 populations). Linear and quadratic Ws equations for three quartiles (25%, median, 75%) are presented for these three species. The length-weight relationship from eight lentic bigmouth sleeper populations was significantly different from that of lotic populations, reflecting higher weights of juvenile fish (< 70 mm total length) in lentic environments. Thus, independent W(s) equations were developed for lotic populations of bigmouth sleepers. W(s) equations were not developed from lentic bigmouth sleeper populations alone due to the low number of applicable populations caused by life history constraints; the equation from combined lentic and lotic populations is suggested for application to lentic bigmouth sleeper populations. These morphometric relationships for amphidromous fishes may improve the ability to assess existing and potential sport fisheries and allow ecological assessment based on fish condition.

Fish population losses from Adirondack Lakes: The role of surface water acidity and acidification

NASA Astrophysics Data System (ADS)

Baker, Joan P.; Warren-Hicks, William J.; Gallagher, James; Christensen, Sigurd W.

1993-04-01

Changes over time in the species composition of fish communities in Adirondack lakes were assessed to determine (1) the approximate numbers offish populations that have been lost and (2) the degree to which fish population losses may have resulted from surface water acidification and acidic deposition. Information on the present-day status offish communities was obtained by the Adirondack Lakes Survey Corporation, which surveyed 1469 Adirondack lakes in 1984-1987 (53% of the total ponded waters in the Adirondack ecological zone). Two hundred and ninety-five of these lakes had been surveyed in 1929-1934 during the first statewide biological survey; 720 had been surveyed in one or more years prior to 1970. Sixteen to 19% of the lakes with adequate historical data appeared to have lost one or more fish populations as a result of acidification. Brook trout and acid-sensitive minnow species had experienced the most widespread effects. Populations of brook trout and acid-sensitive minnows had been lost apparently as a result of acidification from 11% and 19%, respectively, of the lakes with confirmed historical occurrence of these taxa. By contrast, fish species that tend to occur primarily in lower elevation and larger lakes, such as largemouth and smallmouth bass and brown trout, have experienced little to no documented adverse effects. Lakes that were judged to have lost fish populations as a result of acidification had significantly lower; pH and, in most cases, also had higher estimated concentrations of inorganic aluminum and occurred at higher elevations than did lakes with the fish species still present. No other lake characteristics were consistently associated with fish population losses attributed to acidification. The exact numbers and proportions of fish populations affected could not be determined because of limitations on the quantity and quality of historical data. Lakes for which we had adequate historical data to assess long-term trends in fish communities were significantly larger and deeper and have higher pH than do Adirondack lakes in general; thus, fish communities adversely affected by acidification and acidic deposition may be underrepresented in this study.

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.

Desert tortoise annotated bibliography, 1991-2015

USGS Publications Warehouse

Berry, Kristin H.; Lyren, Lisa M.; Mack, Jeremy S.; Brand, L. Arriana; Wood, Dustin A.

2016-03-01

Agassiz’s Desert Tortoise (hereinafter called desert tortoise) is a state- and federally-listed threatened species (U.S. Fish and Wildlife Service, 1990; California Department of Fish and Game, 2015). The first population federally listed as threatened occurred on the Beaver Dam Slope, Utah (U.S. Fish and Wildlife Service, 1980). In 1990, the entire geographic range north and west of the Colorado River was federally listed as threatened (U.S. Fish and Wildlife Service, 1990), with the exception being a small population in northwestern Arizona. The purpose of this annotated bibliography is to support recovery efforts for the species, because populations have continued to decline in spite of designation of critical habitat and publication of a recovery plan (U.S. Fish and Wildlife Service, 1994). For example, between 2005 and 2014, populations in critical habitats declined about 50% (U.S. Fish and Wildlife Service, 2015).

The influence of changes in lifestyle and mercury exposure in riverine populations of the Madeira River (Amazon Basin) near a hydroelectric project.

PubMed

Hacon, Sandra S; Dórea, José G; Fonseca, Márlon de F; Oliveira, Beatriz A; Mourão, Dennys S; Ruiz, Claudia M V; Gonçalves, Rodrigo A; Mariani, Carolina F; Bastos, Wanderley R

2014-02-26

In the Amazon Basin, naturally occurring methylmercury bioaccumulates in fish, which is a key source of protein consumed by riverine populations. The hydroelectric power-plant project at Santo Antônio Falls allows us to compare the Hg exposure of riverine populations sparsely distributed on both sides of the Madeira river before the area is to be flooded. From 2009 to 2011, we concluded a population survey of the area (N = 2,008; representing circa 80% of community residents) that estimated fish consumption and mercury exposure of riverine populations with different degrees of lifestyle related to fish consumption. Fish samples from the Madeira river (N = 1,615) and 110 species were analyzed for Hg. Hair-Hg was significantly lower (p < 0.001) in less isolated communities near to the capital of Porto Velho (median 2.32 ppm) than in subsistence communities in the Cuniã Lake, 180 km from Porto Velho city (median 6.3 ppm). Fish Hg concentrations ranged from 0.01 to 6.06 µg/g, depending on fish size and feeding behavior. Currently available fish in the Madeira river show a wide variability in Hg concentrations. Despite cultural similarities, riparians showed hair-Hg distribution patterns that reflect changes in fish-eating habits driven by subsistence characteristics.

[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.

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.

[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.

Population modelling to compare chronic external radiotoxicity between individual and population endpoints in four taxonomic groups.

PubMed

Alonzo, Frédéric; Hertel-Aas, Turid; Real, Almudena; Lance, Emilie; Garcia-Sanchez, Laurent; Bradshaw, Clare; Vives I Batlle, Jordi; Oughton, Deborah H; Garnier-Laplace, Jacqueline

2016-02-01

In this study, we modelled population responses to chronic external gamma radiation in 12 laboratory species (including aquatic and soil invertebrates, fish and terrestrial mammals). Our aim was to compare radiosensitivity between individual and population endpoints and to examine how internationally proposed benchmarks for environmental radioprotection protected species against various risks at the population level. To do so, we used population matrix models, combining life history and chronic radiotoxicity data (derived from laboratory experiments and described in the literature and the FREDERICA database) to simulate changes in population endpoints (net reproductive rate R0, asymptotic population growth rate λ, equilibrium population size Neq) for a range of dose rates. Elasticity analyses of models showed that population responses differed depending on the affected individual endpoint (juvenile or adult survival, delay in maturity or reduction in fecundity), the considered population endpoint (R0, λ or Neq) and the life history of the studied species. Among population endpoints, net reproductive rate R0 showed the lowest EDR10 (effective dose rate inducing 10% effect) in all species, with values ranging from 26 μGy h(-1) in the mouse Mus musculus to 38,000 μGy h(-1) in the fish Oryzias latipes. For several species, EDR10 for population endpoints were lower than the lowest EDR10 for individual endpoints. Various population level risks, differing in severity for the population, were investigated. Population extinction (predicted when radiation effects caused population growth rate λ to decrease below 1, indicating that no population growth in the long term) was predicted for dose rates ranging from 2700 μGy h(-1) in fish to 12,000 μGy h(-1) in soil invertebrates. A milder risk, that population growth rate λ will be reduced by 10% of the reduction causing extinction, was predicted for dose rates ranging from 24 μGy h(-1) in mammals to 1800 μGy h(-1) in soil invertebrates. These predictions suggested that proposed reference benchmarks from the literature for different taxonomic groups protected all simulated species against population extinction. A generic reference benchmark of 10 μGy h(-1) protected all simulated species against 10% of the effect causing population extinction. Finally, a risk of pseudo-extinction was predicted from 2.0 μGy h(-1) in mammals to 970 μGy h(-1) in soil invertebrates, representing a slight but statistically significant population decline, the importance of which remains to be evaluated in natural settings. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trematodes in snails near raccoon latrines suggest a final host role for this mammal in California Salt Marshes

USGS Publications Warehouse

Lafferty, K.D.; Dunham, E.J.

2005-01-01

Of the 18 trematode species that use the horn snail, Cerithidea californica, as a first intermediate host, 6 have the potential to use raccoons as a final host. The presence of raccoon latrines in Carpinteria Salt Marsh, California, allowed us to investigate associations between raccoons and trematodes in snails. Two trematode species, Probolocoryphe uca and Stictodora hancocki, occurred at higher prevalences in snails near raccoon latrines than in snails away from latrines, suggesting that raccoons may serve as final hosts for these species. Fecal remains indicated that raccoons fed on shore crabs, the second intermediate host for P. uca, and fish, the second intermediate host for S. hancocki. The increase in raccoon populations in the suburban areas surrounding west coast salt marshes could increase their importance as final hosts for trematodes in this system. ?? American Society of Parasitologists 2005.

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

An indigenous religious ritual selects for resistance to a toxicant in a livebearing fish.

PubMed

Tobler, M; Culumber, Z W; Plath, M; Winemiller, K O; Rosenthal, G G

2011-04-23

Human-induced environmental change can affect the evolutionary trajectory of populations. In Mexico, indigenous Zoque people annually introduce barbasco, a fish toxicant, into the Cueva del Azufre to harvest fish during a religious ceremony. Here, we investigated tolerance to barbasco in fish from sites exposed and unexposed to the ritual. We found that barbasco tolerance increases with body size and differs between the sexes. Furthermore, fish from sites exposed to the ceremony had a significantly higher tolerance. Consequently, the annual ceremony may not only affect population structure and gene flow among habitat types, but the increased tolerance in exposed fish may indicate adaptation to human cultural practices in a natural population on a very small spatial scale.

An indigenous religious ritual selects for resistance to a toxicant in a livebearing fish

PubMed Central

Tobler, M.; Culumber, Z. W.; Plath, M.; Winemiller, K. O.; Rosenthal, G. G.

2011-01-01

Human-induced environmental change can affect the evolutionary trajectory of populations. In Mexico, indigenous Zoque people annually introduce barbasco, a fish toxicant, into the Cueva del Azufre to harvest fish during a religious ceremony. Here, we investigated tolerance to barbasco in fish from sites exposed and unexposed to the ritual. We found that barbasco tolerance increases with body size and differs between the sexes. Furthermore, fish from sites exposed to the ceremony had a significantly higher tolerance. Consequently, the annual ceremony may not only affect population structure and gene flow among habitat types, but the increased tolerance in exposed fish may indicate adaptation to human cultural practices in a natural population on a very small spatial scale. PMID:20826470

A physiological perspective on fisheries-induced evolution.

PubMed

Hollins, Jack; Thambithurai, Davide; Koeck, Barbara; Crespel, Amelie; Bailey, David M; Cooke, Steven J; Lindström, Jan; Parsons, Kevin J; Killen, Shaun S

2018-06-01

There is increasing evidence that intense fishing pressure is not only depleting fish stocks but also causing evolutionary changes to fish populations. In particular, body size and fecundity in wild fish populations may be altered in response to the high and often size-selective mortality exerted by fisheries. While these effects can have serious consequences for the viability of fish populations, there are also a range of traits not directly related to body size which could also affect susceptibility to capture by fishing gears-and therefore fisheries-induced evolution (FIE)-but which have to date been ignored. For example, overlooked within the context of FIE is the likelihood that variation in physiological traits could make some individuals within species more vulnerable to capture. Specifically, traits related to energy balance (e.g., metabolic rate), swimming performance (e.g., aerobic scope), neuroendocrinology (e.g., stress responsiveness) and sensory physiology (e.g., visual acuity) are especially likely to influence vulnerability to capture through a variety of mechanisms. Selection on these traits could produce major shifts in the physiological traits within populations in response to fishing pressure that are yet to be considered but which could influence population resource requirements, resilience, species' distributions and responses to environmental change.

Restoring depleted coral-reef fish populations through recruitment enhancement: a proof of concept.

PubMed

Heenan, A; Simpson, S D; Meekan, M G; Healy, S D; Braithwaite, V A

2009-11-01

To determine whether enhancing the survival of new recruits is a sensible target for the restorative management of depleted coral-reef fish populations, settlement-stage ambon damsel fish Pomacentrus amboinensis were captured, tagged and then either released immediately onto small artificial reefs or held in aquaria for 1 week prior to release. Holding conditions were varied to determine whether they affected survival of fish: half the fish were held in bare tanks (non-enriched) and the other half in tanks containing coral and sand (enriched). Holding fish for this short period had a significantly positive effect on survivorship relative to the settlement-stage treatment group that were released immediately. The enrichment of holding conditions made no appreciable difference on the survival of fish once released onto the reef. It did, however, have a positive effect on the survival of fish while in captivity, thus supporting the case for the provision of simple environmental enrichment in fish husbandry. Collecting and holding settlement-stage fish for at least a week before release appear to increase the short-term survival of released fish; whether it is an effective method for longer-term enhancement of locally depleted coral-reef fish populations will require further study.

The population structure and recent colonization history of Oregon threespine stickleback determined using restriction-site associated DNA-sequencing.

PubMed

Catchen, Julian; Bassham, Susan; Wilson, Taylor; Currey, Mark; O'Brien, Conor; Yeates, Quick; Cresko, William A

2013-06-01

Understanding how genetic variation is partitioned across genomes within and among populations is a fundamental problem in ecological and evolutionary genetics. To address this problem, we studied the threespine stickleback fish, which has repeatedly undergone parallel phenotypic and genetic differentiation when oceanic fish have invaded freshwater habitats. While significant evolutionary genetic research has been performed using stickleback from geographic regions that have been deglaciated in the last 20 000 years, less research has focused on freshwater populations that predate the last glacial maximum. We performed restriction-site associated DNA-sequencing (RAD-seq) based population genomic analyses on stickleback from across Oregon, which was not glaciated during the last maximum. We sampled stickleback from coastal, Willamette Basin and central Oregon sites, analysed their genetic diversity using RAD-seq, performed structure analyses, reconstructed their phylogeographic history and tested the hypothesis of recent stickleback introduction into central Oregon, where incidence of this species was only recently documented. Our results showed a clear phylogeographic break between coastal and inland populations, with oceanic populations exhibiting the lowest levels of divergence from one another. Willamette Basin and central Oregon populations formed a clade of closely related populations, a finding consistent with a recent introduction of stickleback into central Oregon. Finally, genome-wide analysis of genetic diversity (π) and correlations of alleles within individuals in subpopulations (FIS) supported a role for introgressive hybridization in coastal populations and a recent expansion in central Oregon. Our results exhibit the power of next-generation sequencing genomic approaches such as RAD-seq to identify both historical population structure and recent colonization history. © 2013 John Wiley & Sons Ltd.

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.

Natural and anthropogenic influences on the distribution of the threatened Neosho madtom in a midwestern warmwater stream

USGS Publications Warehouse

Wildhaber, M.L.; Allert, A.L.; Schmitt, C.J.; Tabor, V.M.; Mulhern, D.; Powell, K.L.; Sowa, S.P.

2000-01-01

We attempted to discern the contributions of physical habitat, water chemistry, nutrients, and contaminants from historic lead-zinc mining activities on the riffle-dwelling benthic fish community of the Spring River, a midwestern warmwater stream that originates in Missouri and flows into Kansas and Oklahoma. The Spring River has a fish community that includes the Neosho madtom Noturus placidus, a species federally listed as threatened. Although anthropogenic factors such as contaminants limited populations and densities of fishes, an integrated assessment of natural and anthropogenic factors was necessary to effectively estimate the influence of the latter. Fish populations in the Spring River, especially Neosho madtoms, seem to be limited by the presence of cadmium, lead, and zinc in water and in benthic invertebrate food sources and by physical habitat. The population density and community structure of fish in the Spring River also seem to be related to water chemistry and nutrients. Concurrently, diminished food availability may be limiting fish populations at some sites where Neosho madtoms are not found. Many of the natural factors that may be limiting Neosho madtom and other riffle-dwelling fish populations in the Spring River probably are characteristic of the physiographic region drained by the upper reach and many of the tributaries of the Spring River. Our results indicate that competition between the Neosho madtom and other species within the riffle-dwelling fish community is an unlikely cause of Neosho madtom population limitation in the Spring River.

Effect of small versus large clusters of fish school on the yield of a purse-seine small pelagic fishery including a marine protected area.

PubMed

Hieu, Nguyen Trong; Brochier, Timothée; Tri, Nguyen-Huu; Auger, Pierre; Brehmer, Patrice

2014-09-01

We consider a fishery model with two sites: (1) a marine protected area (MPA) where fishing is prohibited and (2) an area where the fish population is harvested. We assume that fish can migrate from MPA to fishing area at a very fast time scale and fish spatial organisation can change from small to large clusters of school at a fast time scale. The growth of the fish population and the catch are assumed to occur at a slow time scale. The complete model is a system of five ordinary differential equations with three time scales. We take advantage of the time scales using aggregation of variables methods to derive a reduced model governing the total fish density and fishing effort at the slow time scale. We analyze this aggregated model and show that under some conditions, there exists an equilibrium corresponding to a sustainable fishery. Our results suggest that in small pelagic fisheries the yield is maximum for a fish population distributed among both small and large clusters of school.

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.e., < 100 mm) equaled 0.7 fish per ha, which is indicative of a relatively poor year-class. Lake-wide biomass of dreissenid mussels dropped precipitously in 2008, down to 9.47 kt, and a 96% decline from the 2007 biomass estimate. 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 2008 was 25.62 kt, which was the lowest observed since the survey began in 1973.

Hankin and Reeves' approach to estimating fish abundance in small streams: Limitations and alternatives

USGS Publications Warehouse

Thompson, W.L.

2003-01-01

Hankin and Reeves' (1988) approach to estimating fish abundance in small streams has been applied in stream fish studies across North America. However, their population estimator relies on two key assumptions: (1) removal estimates are equal to the true numbers of fish, and (2) removal estimates are highly correlated with snorkel counts within a subset of sampled stream units. Violations of these assumptions may produce suspect results. To determine possible sources of the assumption violations, I used data on the abundance of steelhead Oncorhynchus mykiss from Hankin and Reeves' (1988) in a simulation composed of 50,000 repeated, stratified systematic random samples from a spatially clustered distribution. The simulation was used to investigate effects of a range of removal estimates, from 75% to 100% of true fish abundance, on overall stream fish population estimates. The effects of various categories of removal-estimates-to-snorkel-count correlation levels (r = 0.75-1.0) on fish population estimates were also explored. Simulation results indicated that Hankin and Reeves' approach may produce poor results unless removal estimates exceed at least 85% of the true number of fish within sampled units and unless correlations between removal estimates and snorkel counts are at least 0.90. A potential modification to Hankin and Reeves' approach is the inclusion of environmental covariates that affect detection rates of fish into the removal model or other mark-recapture model. A potential alternative approach is to use snorkeling combined with line transect sampling to estimate fish densities within stream units. As with any method of population estimation, a pilot study should be conducted to evaluate its usefulness, which requires a known (or nearly so) population of fish to serve as a benchmark for evaluating bias and precision of estimators.

Random and systematic sampling error when hooking fish to monitor skin fluke (Benedenia seriolae) and gill fluke (Zeuxapta seriolae) burden in Australian farmed yellowtail kingfish (Seriola lalandi).

PubMed

Fensham, J R; Bubner, E; D'Antignana, T; Landos, M; Caraguel, C G B

2018-05-01

The Australian farmed yellowtail kingfish (Seriola lalandi, YTK) industry monitor skin fluke (Benedenia seriolae) and gill fluke (Zeuxapta seriolae) burden by pooling the fluke count of 10 hooked YTK. The random and systematic error of this sampling strategy was evaluated to assess potential impact on treatment decisions. Fluke abundance (fluke count per fish) in a study cage (estimated 30,502 fish) was assessed five times using the current sampling protocol and its repeatability was estimated the repeatability coefficient (CR) and the coefficient of variation (CV). Individual body weight, fork length, fluke abundance, prevalence, intensity (fluke count per infested fish) and density (fluke count per Kg of fish) were compared between 100 hooked and 100 seined YTK (assumed representative of the entire population) to estimate potential selection bias. Depending on the fluke species and age category, CR (expected difference in parasite count between 2 sampling iterations) ranged from 0.78 to 114 flukes per fish. Capturing YTK by hooking increased the selection of fish of a weight and length in the lowest 5th percentile of the cage (RR = 5.75, 95% CI: 2.06-16.03, P-value = 0.0001). These lower end YTK had on average an extra 31 juveniles and 6 adults Z. seriolae per Kg of fish and an extra 3 juvenile and 0.4 adult B. seriolae per Kg of fish, compared to the rest of the cage population (P-value < 0.05). Hooking YTK on the edge of the study cage biases sampling towards the smallest and most heavily infested fish in the population, resulting in poor repeatability (more variability amongst sampled fish) and an overestimation of parasite burden in the population. In this particular commercial situation these finding supported that health management program, where the finding of an underestimation of parasite burden could provide a production impact on the study population. In instances where fish populations and parasite burdens are more homogenous, sampling error may be less severe. Sampling error when capturing fish from sea cage is difficult to predict. The amplitude and direction of this error should be investigated for a given cultured fish species across a range of parasite burden and fish profile scenarios. Copyright © 2018 Elsevier B.V. All rights reserved.

Microhabitat use, not temperature, regulates intensity of Gyrodactylus cichlidarum long-term infection on farmed tilapia--are parasites evading competition or immunity?

PubMed

Rubio-Godoy, Miguel; Muñoz-Córdova, Germán; Garduño-Lugo, Mario; Salazar-Ulloa, Martha; Mercado-Vidal, Gabriel

2012-02-10

Gyrodactylids (Monogenea) are ectoparasites of fish, some of which negatively affect commercially valuable fishes. Temperature strongly regulates population dynamics of these viviparous flatworms in farmed and wild fish populations, with most gyrodactylid species showing positive temperature-abundance associations. In agreement with epidemiological theory, numerous laboratory studies demonstrate that these parasites cannot persist in confined fish populations without periodic introduction of susceptible hosts. Extinction of gyrodactylid populations is due to host immunity, which develops in several fish species. In this one-year study, we followed populations of the recognized pathogen Gyrodactylus cichlidarum infecting four genetic groups of confined tilapia (wild type Nile tilapia Oreochromis niloticus niloticus, red O. n. niloticus, Mozambique tilapia O. mossambicus and a red synthetic population called Pargo-UNAM) kept under farming conditions and subject to natural environmental fluctuations. Based on the antecedents given, we postulated the following three hypotheses: (1) parasite abundance will be regulated by water temperature; (2) parasites will induce host mortality, particularly during periods of rapid infrapopulation growth; and (3) gyrodactylid populations will eventually become extinct on confined fish hosts. We disproved the three hypotheses: (1) parasite numbers fluctuated independently of temperature but were associated to changes in microhabitat use; (2) although gyrodactylid populations exhibited considerable growth, no evidence was found of negative effects on the hosts; and (3) infections persisted for one year on confined fish. Microhabitat use changed over time, with most worms apparently migrating anteriorly from the caudal fin and ending on the pectoral fins. Gyrodactylid populations followed similar trajectories in all fish, aggregating and dispersing repeatedly. Several instances were found where increased parasite dispersion coincided with increased intensity of infection; as well as the opposite, where increased aggregation coincided with parasite population declines. Three alternative explanations could account for these observations: that parasites (1) experience differential mortality on different anatomical regions of the fish; (2) migrate to avoid intraspecific competition; and (3) migrate to escape localized immune responses induced by infection. Our data do not allow us to demonstrate which of these alternatives is correct, so we discuss the merits of each. We provide circumstantial evidence in support of the third explanation, because as shown in other fish host-gyrodactylid interactions where immune responses have been characterized, in this study worms progressively moved away from fins with high mucus cell density to those with low density - what would be anticipated if immune defenses occur and reach the fish surface through mucus. Copyright © 2011 Elsevier B.V. All rights reserved.

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.

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

Genetic and Phenotypic Catalog of Native Resident Trout of the interior Columbia River Basin : FY-2001 Report : Populations in the Wenatchee, Entiat, Lake Chelan and Methow River Drainages.

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

Trotter, Patrick C.

2001-10-01

The 1994 Fish and Wildlife Program of the Northwest Power Planning Council specifies the recovery and preservation of population health of native resident fishes of the Columbia River Basin. Among the native resident species of concern are interior rainbow trout of the Columbia River redband subspecies Oncorhynchus mykiss gairdneri 1 and westslope cutthroat trout O. clarki lewisi. The westslope cutthroat trout has been petitioned for listing under the U. S. Endangered Species Act (American Wildlands et al. 1997). Before at-risk populations can be protected, their presence and status must be established. Where introgression from introduced species is a concern, asmore » in the case of both westslope cutthroat trout and redband rainbow trout, genetic issues must be addressed as well. As is true with native trout elsewhere in the western United States (Behnke 1992), most of the remaining pure populations of these species in the Columbia River Basin are in relatively remote headwater reaches. The objective of this project was to photo-document upper Columbia Basin native resident trout populations in Washington, and to ascertain their species or subspecies identity and relative genetic purity using a nonlethal DNA technique. FY-2001 was year three (and final year) of a project in which we conducted field visits to remote locations to seek out and catalog these populations. In FY-2001 we worked in collaboration with the Wenatchee National Forest to catalog populations in the Wenatchee, Entiat, Lake Chelan, and Methow River drainages of Washington State.« less

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.

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.

Ecology of Listeria spp. in a fish farm and molecular typing of Listeria monocytogenes from fish farming and processing companies.

PubMed

Miettinen, Hanna; Wirtanen, Gun

2006-11-01

This study focused on the ecology of Listeria monocytogenes in a fish farm by following the changes in its occurrence in different types of samples for a three year period. In addition, L. monocytogenes isolates from different seafood industry areas were compared with pulsed field gel electrophoresis (PFGE) typing to discover possible associations between primary production, further processing and final products. Weather conditions were found to have a strong influence on the probability of finding Listeria spp. in a fish farm environment. The number of samples contaminated with Listeria spp. was typically bigger after rainy periods. Brook and river waters as well as other runoff waters seemed to be the main contamination source at the farm studied. The farmed fish originally found to carry L. monocytogenes become gradually Listeria free. The time needed for the purification of the fish was several months. The sea bottom soil samples were the ones that preserved the L. monocytogenes contamination the longest time. It can be stated that the fish and fish farm equipment studied did not spread listeria contamination. On the contrary, they were found to suffer from listeria contamination coming from outside sources like the brook water. There was a wide range of different L. monocytogenes PFGE-pulsotypes (30) found at 15 Finnish fish farms and fish processing factories. L. monocytogenes isolates from the final products often belonged to the same pulsotypes as did the isolates from the processing environment as well as from the raw fish. This suggests that, in addition to the fish processing factory environment, the fish raw materials are important sources of L. monocytogenes contamination in final products.

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.

The Influence of Changes in Lifestyle and Mercury Exposure in Riverine Populations of the Madeira River (Amazon Basin) near a Hydroelectric Project

PubMed Central

Hacon, Sandra S.; Dórea, José G.; Fonseca, Márlon de F.; Oliveira, Beatriz A.; Mourão, Dennys S.; Ruiz, Claudia M. V.; Gonçalves, Rodrigo A.; Mariani, Carolina F.; Bastos, Wanderley R.

2014-01-01

In the Amazon Basin, naturally occurring methylmercury bioaccumulates in fish, which is a key source of protein consumed by riverine populations. The hydroelectric power-plant project at Santo Antônio Falls allows us to compare the Hg exposure of riverine populations sparsely distributed on both sides of the Madeira river before the area is to be flooded. From 2009 to 2011, we concluded a population survey of the area (N = 2,008; representing circa 80% of community residents) that estimated fish consumption and mercury exposure of riverine populations with different degrees of lifestyle related to fish consumption. Fish samples from the Madeira river (N = 1,615) and 110 species were analyzed for Hg. Hair-Hg was significantly lower (p < 0.001) in less isolated communities near to the capital of Porto Velho (median 2.32 ppm) than in subsistence communities in the Cuniã Lake, 180 km from Porto Velho city (median 6.3 ppm). Fish Hg concentrations ranged from 0.01 to 6.06 µg/g, depending on fish size and feeding behavior. Currently available fish in the Madeira river show a wide variability in Hg concentrations. Despite cultural similarities, riparians showed hair-Hg distribution patterns that reflect changes in fish-eating habits driven by subsistence characteristics. PMID:24577285

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

A Natural History Summary and Survey Protocol for the Southwestern Willow Flycatcher

USGS Publications Warehouse

Sogge, Mark K.; ,; Ahlers, Darrell; ,; Sferra, Susan J.; ,

2010-01-01

The Southwestern Willow Flycatcher (Empidonax traillii extimus) has been the subject of substantial research, monitoring, and management activity since it was listed as an endangered species in 1995. When proposed for listing in 1993, relatively little was known about the flycatcher's natural history, and there were only 30 known breeding sites supporting an estimated 111 territories rangewide (Sogge and others, 2003a). Since that time, thousands of presence/absences surveys have been conducted throughout the historical range of the flycatcher, and many studies of its natural history and ecology have been completed. As a result, the ecology of the flycatcher is much better understood than it was just over a decade ago. In addition, we have learned that the current status of the flycatcher is better than originally thought: as of 2007, the population was estimated at approximately 1,300 territories distributed among approximately 280 breeding sites (Durst and others, 2008a). Concern about the Southwestern Willow Flycatcher on a rangewide scale was brought to focus by Unitt (1987), who described declines in flycatcher abundance and distribution throughout the Southwest. E. t. extimus populations declined during the 20th century, primarily because of habitat loss and modification from activities, such as dam construction and operation, groundwater pumping, water diversions, and flood control. In 1991, the U.S. Fish and Wildlife Service (USFWS) designated the Southwestern Willow Flycatcher as a candidate category 1 species (U.S. Fish and Wildlife Service, 1991). In July 1993, the USFWS proposed to list E. t. extimus as an endangered species and to designate critical habitat under the Act (U.S. Fish and Wildlife Service, 1993). A final rule listing E. t. extimus as endangered was published in February 1995 (U.S. Fish and Wildlife Service, 1995); critical habitat was designated in 1997 (U.S. Fish and Wildlife Service, 1997). The USFWS Service released a Recovery Plan for the Southwestern Willow Flycatcher in 2002 (U.S. Fish and Wildlife Service, 2002), and re-designated critical habitat in 2005 (U.S. Fish and Wildlife Service, 2005).

Working with, not against, coral-reef fisheries

NASA Astrophysics Data System (ADS)

Birkeland, Charles

2017-03-01

The fisheries policies of some Pacific island nations are more appropriate to the biology of their resources than are some of the fisheries policies of more industrialized countries. Exclusive local ownership of natural resources in Palau encourages adjustive management on biologically relevant scales of time and space and promotes responsibility by reducing the tragedy of the commons. The presence of large individuals in fish populations and adequate size of spawning aggregations are more efficient and meaningful cues for timely management than are surveys of abundance or biomass. Taking fish from populations more than halfway to their carrying capacity is working favorably with the fishery because removing fish potentially increases resource stability by negative feedback between stock size and population production. Taking the same amount of fish from a population below half its carrying capacity is working against the fishery, making the population unstable, because reducing the reproductive stock potentially accelerates reduction of the population production by positive feedback. Reef fish are consumed locally, while Palauan laws ban the export of reef resources. This is consistent with the high gross primary production with little excess net production from undisturbed coral-reef ecosystems. The relatively rapid growth rates, short life spans, reliable recruitment and wide-ranging movements of open-ocean fishes such as scombrids make them much more productive than coral-reef fishes. The greater fisheries yield per square kilometer in the open ocean multiplied by well over a thousand times the area of the exclusive economic zone than that of Palau's coral reefs should encourage Palauans to keep reef fishes for subsistence and to feed tourists open-ocean fishes. Fisheries having only artisanal means should be encouraged to increase the yield and sustainability by moving away from coral reefs to bulk harvesting of nearshore pelagics.

76 FR 49786 - Notice of Availability of the Final Environmental Impact Statement/Environmental Impact Report...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-11

... of Fish and Game (CDFG), the lead State agency, have prepared a joint Final EIS/EIR for the proposed... decision. The CDFG will advance its recommendations to the California Fish and Game Commission (Commission...

Geographical variation in sound production in the anemonefish Amphiprion akallopisos.

PubMed

Parmentier, E; Lagardère, J P; Vandewalle, P; Fine, M L

2005-08-22

Because of pelagic-larval dispersal, coral-reef fishes are distributed widely with minimal genetic differentiation between populations. Amphiprion akallopisos, a clownfish that uses sound production to defend its anemone territory, has a wide but disjunct distribution in the Indian Ocean. We compared sounds produced by these fishes from populations in Madagascar and Indonesia, a distance of 6500 km. Differentiation of agonistic calls into distinct types indicates a complexity not previously recorded in fishes' acoustic communication. Moreover, various acoustic parameters, including peak frequency, pulse duration, number of peaks per pulse, differed between the two populations. The geographic comparison is the first to demonstrate 'dialects' in a marine fish species, and these differences in sound parameters suggest genetic divergence between these two populations. These results highlight the possible approach for investigating the role of sounds in fish behaviour in reproductive divergence and speciation.

Dynamics of an introduced and unexploited Lake Whitefish population in Lake Pend Oreille, Idaho

USGS Publications Warehouse

Hosack, Michael A.; Hansen, Michael J.; Horner, Ned J.

2014-01-01

To evaluate biological potential of a commercial fishery for an unexploited Lake Whitefish Coregonus clupeaformis population in Lake Pend Oreille, Idaho, we estimated population parameters related to production and yield. The length frequency based on trap-netting in autumn 2005 was normal with a mean of 448 mm TL, whereas the length frequency based on gillnetting in spring 2006 was bimodal with a mean of 390 mm TL. Sex composition was skewed toward females (0.66) during autumn trap-netting. Shape parameters β of weight–length models for females (β = 3.38) and males (β = 3.45) were similar to those of other unexploited populations. Instantaneous growth rates K for females (K = 0.144 per year) and males (K = 0.153 per year) were among the lowest for unexploited populations across the species’ range. Age at 50% maturity (females: 6.5 years; males: 6.0 years) and length at 50% maturity (females: 390 mm TL; males: 378 mm TL) were high for unexploited populations. The natural mortality rate M (0.149 per year, ages 11–36) was among the lowest observed for unexploited populations. Adult population density was lower than that of other populations based on total surface area (mean = 1.35 fish/ha; 95% confidence interval [CI] = 1.11–1.78 fish/ha) but was average based on lake area shallower than 70 m (4.07 fish/ha; 95% CI = 3.35–5.35 fish/ha). Population density of juveniles and adults averaged 84 fish/ha (95% CI = 52–143 fish/ha) over the entire surface area and 278 fish/ha (95% CI = 173–474 fish/ha) over depths shallower than 70 m. The difference between the low M of the unexploited population in Lake Pend Oreille (M = 0.149 per year; annual mortality rate A = 14%) and the high sustainable total mortality Z of exploited stocks in the Laurentian Great Lakes (Z = 1.204; A = 70%) suggests a large scope for sustainable fishing mortality F (1.055 per year; exploitation rate u = 61%) that is equivalent to a sustainable Lake Whitefish harvest of 55,000 individuals (50,000–60,000 individuals) and 49,000 kg (45,000–54,000 kg) from Lake Pend Oreille.

Spatial and temporal heterogeneity of infectious hematopoietic necrosis virus in Pacific Northwest salmonids

USGS Publications Warehouse

Breyta, Rachel; Black, Allison; Kaufman, John; Kurath, Gael

2016-01-01

The aquatic rhaboviral pathogen infectious hematopoietic necrosis virus (IHNV) causes acute disease in juvenile fish of a number of populations of Pacific salmonid species. Heavily managed in both marine and freshwater environments, these fish species are cultured during the juvenile stage in freshwater conservation hatcheries, where IHNV is one of the top three infectious diseases that cause serious morbidity and mortality. Therefore, a comprehensive study of viral genetic surveillance data representing 2590 field isolates collected between 1958 and 2014 was conducted to determine the spatial and temporal patterns of IHNV in the Pacific Northwest of the contiguous United States. Prevalence of infection varied over time, fluctuating over a rough 5–7 year cycle. The genetic analysis revealed numerous subgroups of IHNV, each of which exhibited spatial heterogeneity. Within all subgroups, dominant genetic types were apparent, though the temporal patterns of emergence of these types varied among subgroups. Finally, the affinity or fidelity of subgroups to specific host species also varied, where UC subgroup viruses exhibited a more generalist profile and all other subgroups exhibited a specialist profile. These complex patterns are likely synergistically driven by numerous ecological, pathobiological, and anthropogenic factors. Since only a few anthropogenic factors are candidates for managed intervention aimed at improving the health of threatened or endangered salmonid fish populations, determining the relative impact of these factors is a high priority for future studies.

Behavioral and Single-Neuron Sensitivity to Millisecond Variations in Temporally Patterned Communication Signals

PubMed Central

Baker, Christa A.; Ma, Lisa; Casareale, Chelsea R.

2016-01-01

In many sensory pathways, central neurons serve as temporal filters for timing patterns in communication signals. However, how a population of neurons with diverse temporal filtering properties codes for natural variation in communication signals is unknown. Here we addressed this question in the weakly electric fish Brienomyrus brachyistius, which varies the time intervals between successive electric organ discharges to communicate. These fish produce an individually stereotyped signal called a scallop, which consists of a distinctive temporal pattern of ∼8–12 electric pulses. We manipulated the temporal structure of natural scallops during behavioral playback and in vivo electrophysiology experiments to probe the temporal sensitivity of scallop encoding and recognition. We found that presenting time-reversed, randomized, or jittered scallops increased behavioral response thresholds, demonstrating that fish's electric signaling behavior was sensitive to the precise temporal structure of scallops. Next, using in vivo intracellular recordings and discriminant function analysis, we found that the responses of interval-selective midbrain neurons were also sensitive to the precise temporal structure of scallops. Subthreshold changes in membrane potential recorded from single neurons discriminated natural scallops from time-reversed, randomized, and jittered sequences. Pooling the responses of multiple neurons improved the discriminability of natural sequences from temporally manipulated sequences. Finally, we found that single-neuron responses were sensitive to interindividual variation in scallop sequences, raising the question of whether fish may analyze scallop structure to gain information about the sender. Collectively, these results demonstrate that a population of interval-selective neurons can encode behaviorally relevant temporal patterns with millisecond precision. SIGNIFICANCE STATEMENT The timing patterns of action potentials, or spikes, play important roles in representing information in the nervous system. However, how these temporal patterns are recognized by downstream neurons is not well understood. Here we use the electrosensory system of mormyrid weakly electric fish to investigate how a population of neurons with diverse temporal filtering properties encodes behaviorally relevant input timing patterns, and how this relates to behavioral sensitivity. We show that fish are behaviorally sensitive to millisecond variations in natural, temporally patterned communication signals, and that the responses of individual midbrain neurons are also sensitive to variation in these patterns. In fact, the output of single neurons contains enough information to discriminate stereotyped communication signals produced by different individuals. PMID:27559179

Behavioral and Single-Neuron Sensitivity to Millisecond Variations in Temporally Patterned Communication Signals.

PubMed

Baker, Christa A; Ma, Lisa; Casareale, Chelsea R; Carlson, Bruce A

2016-08-24

In many sensory pathways, central neurons serve as temporal filters for timing patterns in communication signals. However, how a population of neurons with diverse temporal filtering properties codes for natural variation in communication signals is unknown. Here we addressed this question in the weakly electric fish Brienomyrus brachyistius, which varies the time intervals between successive electric organ discharges to communicate. These fish produce an individually stereotyped signal called a scallop, which consists of a distinctive temporal pattern of ∼8-12 electric pulses. We manipulated the temporal structure of natural scallops during behavioral playback and in vivo electrophysiology experiments to probe the temporal sensitivity of scallop encoding and recognition. We found that presenting time-reversed, randomized, or jittered scallops increased behavioral response thresholds, demonstrating that fish's electric signaling behavior was sensitive to the precise temporal structure of scallops. Next, using in vivo intracellular recordings and discriminant function analysis, we found that the responses of interval-selective midbrain neurons were also sensitive to the precise temporal structure of scallops. Subthreshold changes in membrane potential recorded from single neurons discriminated natural scallops from time-reversed, randomized, and jittered sequences. Pooling the responses of multiple neurons improved the discriminability of natural sequences from temporally manipulated sequences. Finally, we found that single-neuron responses were sensitive to interindividual variation in scallop sequences, raising the question of whether fish may analyze scallop structure to gain information about the sender. Collectively, these results demonstrate that a population of interval-selective neurons can encode behaviorally relevant temporal patterns with millisecond precision. The timing patterns of action potentials, or spikes, play important roles in representing information in the nervous system. However, how these temporal patterns are recognized by downstream neurons is not well understood. Here we use the electrosensory system of mormyrid weakly electric fish to investigate how a population of neurons with diverse temporal filtering properties encodes behaviorally relevant input timing patterns, and how this relates to behavioral sensitivity. We show that fish are behaviorally sensitive to millisecond variations in natural, temporally patterned communication signals, and that the responses of individual midbrain neurons are also sensitive to variation in these patterns. In fact, the output of single neurons contains enough information to discriminate stereotyped communication signals produced by different individuals. Copyright © 2016 the authors 0270-6474/16/368985-16$15.00/0.

Chemical contaminants (trace metals, persistent organic pollutants) in albacore tuna from western Indian and south-eastern Atlantic Oceans: Trophic influence and potential as tracers of populations.

PubMed

Chouvelon, Tiphaine; Brach-Papa, Christophe; Auger, Dominique; Bodin, Nathalie; Bruzac, Sandrine; Crochet, Sylvette; Degroote, Maxime; Hollanda, Stephanie J; Hubert, Clarisse; Knoery, Joël; Munschy, Catherine; Puech, Alexis; Rozuel, Emmanuelle; Thomas, Bastien; West, Wendy; Bourjea, Jérôme; Nikolic, Natacha

2017-10-15

Albacore tuna (Thunnus alalunga) is a highly commercial fish species harvested in the world's Oceans. Identifying the potential links between populations is one of the key tools that can improve the current management across fisheries areas. In addition to characterising populations' contamination state, chemical compounds can help refine foraging areas, individual flows and populations' structure, especially when combined with other intrinsic biogeochemical (trophic) markers such as carbon and nitrogen stable isotopes. This study investigated the bioaccumulation of seven selected trace metals - chromium, nickel, copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg) and lead - in the muscle of 443 albacore tunas, collected over two seasons and/or years in the western Indian Ocean (WIO: Reunion Island and Seychelles) and in the south-eastern Atlantic Ocean (SEAO: South Africa). The main factor that explained metal concentration variability was the geographic origin of fish, rather than the size and the sex of individuals, or the season/year of sampling. The elements Cu, Zn, Cd and Hg indicated a segregation of the geographic groups most clearly. For similar sized-individuals, tunas from SEAO had significantly higher concentrations in Cu, Zn and Cd, but lower Hg concentrations than those from WIO. Information inferred from the analysis of trophic markers (δ 13 C, δ 15 N) and selected persistent organic pollutants, as well as information on stomach contents, corroborated the geographical differences obtained by trace metals. It also highlighted the influence of trophic ecology on metal bioaccumulation. Finally, this study evidenced the potential of metals and chemical contaminants in general as tracers, by segregating groups of individuals using different food webs or habitats, to better understand spatial connectivity at the population scale. Limited flows of individuals between the SEAO and the WIO are suggested. Albacore as predatory fish also provided some information on environmental and food web chemical contamination in the different study areas. Copyright © 2017 Elsevier B.V. All rights reserved.

Estrogenicity and intersex in juvenile rainbow trout (Oncorhynchus mykiss) exposed to Pine/Eucalyptus pulp and paper production effluent in Chile.

PubMed

Chiang, Gustavo; Barra, Ricardo; Díaz-Jaramillo, Mauricio; Rivas, Meyling; Bahamonde, Paulina; Munkittrick, Kelly R

2015-07-01

Pulp and paper mill effluents (PPMEs) have been shown to increase gonad size, cause early maturation, and disrupt hormone functions in native and non-native Chilean fish. In this study, we assessed reproductive (plasma vitellogenin; VTG, gonad development) and metabolic (ethoxyresorufin-O-deethylase activity; EROD) end points, relative liver size (LSI) and condition factor (K) of juvenile female and male rainbow trout exposed to effluents. Unlike previous studies, which have focus either on the specific effects of effluent on fish in laboratory exposures or biotic population statuses downstream of discharge sites, we simultaneously assessed the impacts of PPMES on trout using two approaches: (1) laboratory exposures of tertiary treated PPME produced from processing Eucalyptus globulus or Pinus radiata; and (2) in situ bioassay downstream of the combined discharge of the same pulp mill. Despite an increase in the average gonadosomatic index (GSI) in exposed fish, no statistical differences in gonad size between exposed and unexposed individuals was detected. However, both female and male fish exposed to effluents showed significantly higher concentrations of plasma VTG, so more in fish exposed to Eucalyptus-based effluent when compared to Pinus PPME. In addition, male fish showed intersex characteristics in all exposure assays (Eucaliptus and Pinus) and, despite the low concentration of effluent in the river (<1% [v/v]), similar responses were observed in the caged fish. Finally, EROD activity was induced in both in situ exposures and laboratory assays at the higher PPME concentration (60-85% PPME). This study confirms estrogenic effects in Chilean fish exposed to PPME and the necessity for biological effects monitoring in addition to the assessment of physical-chemical endpoints as required in current government regulations. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of enhanced hydrological connectivity on Mediterranean salt marsh fish assemblages with emphasis on the endangered Spanish toothcarp (Aphanius iberus).

PubMed

Prado, Patricia; Alcaraz, Carles; Jornet, Lluis; Caiola, Nuno; Ibáñez, Carles

2017-01-01

The hydrological connectivity between the salt marsh and the sea was partially restored in a Mediterranean wetland containing isolated ponds resulting from former salt extraction and aquaculture activities. A preliminary assessment provided evidence that ponds farther from the sea hosted very large numbers of the endangered Spanish toothcarp, Aphanius iberus , suggesting that individuals had been trapped and consequently reach unnaturally high densities. In order to achieve both habitat rehabilitation and toothcarp conservation, efforts were made to create a gradient of hydrologically connected areas, including isolated fish reservoirs, semi-isolated, and connected salt marsh-sea areas that could allow migratory movements of fish and provide some protection for A. iberus . The fish community was monitored prior to, and for three years after rehabilitation. Results showed an increase in the number of fish species within semi-isolated areas (Zone A), whereas areas adjacent to the sea (Zone B) increased the number of marine species and decreased that of estuarine species (ES). Yet overall differences in fish assemblages were much higher between zones than among study years. Generalized linear models (GLMs) evidenced that distance to the sea was the most important variable explaining the local diversity of the fish community after restoration, with occasional influence of other factors such as temperature, and depth. The abundance of A. iberus was consistently higher in semi-isolated areas at greater distances from the sea, but a decline occurred in both zones and in isolated reservoir ponds after restoration efforts, which may be attributable to interannual differences in recruitment success and, to a lesser extent, to dispersal into adjacent habitats. A negative effect of restoration works on fish population cannot be excluded, but the final outcome of the intervention likely needs a longer period.

75 FR 51420 - Removing Regulations Implementing the Fish and Wildlife Conservation Act

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-20

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 83 [Docket No. FWS-R9-WSR-2010... and Wildlife Conservation Act AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are removing our regulations implementing the Fish...

Role of egg predation by haddock in the decline of an Atlantic herring population

PubMed Central

Richardson, David E.; Hare, Jonathan A.; Fogarty, Michael J.; Link, Jason S.

2011-01-01

Theoretical studies suggest that the abrupt and substantial changes in the productivity of some fisheries species may be explained by predation-driven alternate stable states in their population levels. With this hypothesis, an increase in fishing or a natural perturbation can drive a population from an upper to a lower stable-equilibrium population level. After fishing is reduced or the perturbation ended, this low population level can persist due to the regulatory effect of the predator. Although established in theoretical studies, there is limited empirical support for predation-driven alternate stable states in exploited marine fish populations. We present evidence that egg predation by haddock (Melanogrammus aeglefinus) can cause alternate stable population levels in Georges Bank Atlantic herring (Clupea harengus). Egg predation by haddock explains a substantial decoupling of herring spawning stock biomass (an index of egg production) from observed larval herring abundance (an index of egg hatching). Estimated egg survival rates ranged from <2–70% from 1971 to 2005. A population model incorporating egg predation and herring fishing explains the major population trends of Georges Bank herring over four decades and predicts that, when the haddock population is high, seemingly conservative levels of fishing can still precipitate a severe decline in the herring population. These findings illustrate how efforts to rebuild fisheries can be undermined by not incorporating ecological interactions into fisheries models and management plans. PMID:21825166

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

PubMed

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

2015-10-22

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

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

PubMed Central

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

2015-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2015-10-01

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

Assessment of the Fshery Improvement Opportunities on the Pend Oreille River, 1990 Annual Report.

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

Ashe, Becky L.; Lillengreen, Kelly L.; Vella, John J.

1991-03-01

The purpose of this study was to assess the fishery improvement opportunities on the Box Canyon portion of the Pend Oreilla River. This three year study was initiated as part of the Northwest Power Planning Council's 1987 Columbia River Basin Fish and Wildlife Program. This report contains the findings of the third and final year of the study. The objectives of the third year of the study were to determine the relative abundance of each species in the river and sloughs; the population levels in five selected tributaries and, if possible, for fish in the river and sloughs; each speciesmore » growth rate, feeding habits abundance preferred prey, and migration patterns; and the seasonal movement patterns and habitat utilization of largemouth bass. 64 refs., 8 figs., 263., tabs.« less

Bioenergetics in ecosystems

USGS Publications Warehouse

Madenjian, Charles P.; Farrell, Anthony P.

2011-01-01

A bioenergetics model for a fish can be defined as a quantitative description of the fish’s energy budget. Bioenergetics modeling can be applied to a fish population in a lake, river, or ocean to estimate the annual consumption of food by the fish population; such applications have proved to be useful in managing fisheries. In addition, bioenergetics models have been used to better understand fish growth and consumption in ecosystems, to determine the importance of the role of fish in cycling nutrients within ecosystems, and to identify the important factors regulating contaminant accumulation in fish from lakes, rivers, and oceans.

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 using size-specific fish counts, allowing for spatiotemporal comparisons of abundance and demographic structure of fish populations across protected and fished areas. Results of the meta-analysis revealed that: (1) although fish density was higher inside MPAs than in fished reefs at each sampling period, reef-wide density often increased or remained stable over time; and (2) increases in large-bodied fish were evident reef-wide between survey periods, indicating that positive demographic shifts occurred simultaneously in both MPAs and adjacent areas. Increases in large-bodied fish were observed across a range of taxa, but were most prominent in families directly targeted by fishermen. These results suggest that over relatively few years of protection, Philippine MPAs promoted beneficial shifts in population structure throughout entire reef systems, rather than simply maintaining stable populations within their borders. Relationships between MPA age and shifts in fish density or demographic structure were rare, but may have been precluded by the relatively short period between replicate surveys. Although increases in fish density inside MPAs were occasionally associated with MPA size, there were no significant relationships between the size of MPAs and reef-wide increases in fish density. The reef-wide framework of MPA assessment used in this study has the advantage of treating MPAs and fished reefs as an integrated system, thus revealing trends that would be indistinguishable in traditional spatial comparisons between MPAs and fished reefs. The impact of MPAs on fishing-induced life-history traits was assessed by comparing growth and maturation patterns exhibited by six reef-fish species inside and outside five MPAs and adjacent, fished reefs in Zambales, Luzon, Philippines. This analysis demonstrated considerable variation in terminal body-sizes (Linf) and growth rates (K) between conspecifics in MPAs and fished reefs. Three of the four experimental species directly targeted for food in the region (Acanthurus nigrofuscus, Ctenochaetus striatus, and Parupeneus multifasciatus) exhibited greater Linf, lower K, or both characteristics inside at least one MPA compared to populations in adjacent, fished reefs. Life-history shifts were concentrated in the oldest and largest MPAs, but occurred at least once in each of the five MPAs that were examined. A fourth species harvested for food (Ctenochaetus binotatus), as well as a species targeted for the aquarium trade (Zebrasoma scopas) and a non-target species (Plectroglyphidodon lacrymatus) did not exhibit differential phenotypes between MPAs and fished reefs. The relatively high frequency of alterations to life-history characteristics across MPAs in harvested species suggests that observed changes in the density and size-structure of harvested fish populations inside MPAs are likely driven by spatial disparities in fishing pressure, and are the result of phenotypic changes rather than increased longevity.

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.

Standardization of a geo-referenced fishing data set for the Indian Ocean bigeye tuna, Thunnus obesus (1952-2014)

NASA Astrophysics Data System (ADS)

Wibawa, Teja A.; Lehodey, Patrick; Senina, Inna

2017-02-01

Geo-referenced catch and fishing effort data of the bigeye tuna fisheries in the Indian Ocean over 1952-2014 were analyzed and standardized to facilitate population dynamics modeling studies. During this 62-year historical period of exploitation, many changes occurred both in the fishing techniques and the monitoring of activity. This study includes a series of processing steps used for standardization of spatial resolution, conversion and standardization of catch and effort units, raising of geo-referenced catch into nominal catch level, screening and correction of outliers, and detection of major catchability changes over long time series of fishing data, i.e., the Japanese longline fleet operating in the tropical Indian Ocean. A total of 30 fisheries were finally determined from longline, purse seine and other-gears data sets, from which 10 longline and 4 purse seine fisheries represented 96 % of the whole historical geo-referenced catch. Nevertheless, one-third of total nominal catch is still not included due to a total lack of geo-referenced information and would need to be processed separately, accordingly to the requirements of the study. The geo-referenced records of catch, fishing effort and associated length frequency samples of all fisheries are available at doi:10.1594/PANGAEA.864154.

Survival and migration behavior of juvenile salmonids at McNary Dam, 2004, Final report of research

USGS Publications Warehouse

Perry, Russell W.; Braatz, Amy C.; Fielding, Scott D.; Lucchesi, Joel N.; Plumb, John M.; Adams, Noah S.; Rondorf, Dennis W.

2005-01-01

During 2004, the USGS Columbia River Research Laboratory conducted a study at McNary Dam using radio telemetry to estimate passage and survival parameters of juvenile salmonids. Our primary objective was to estimate these parameters under ambient environmental and operational conditions, and thus project-wide treatments were not implemented. The primary dam operation consisted of “biop” spill, where spill occurred at night between 1800 and 0600 hours, and no spill occurred between 0600 and 1800 hours for the majority of our study period. During the spring study period, we radio-tagged and released 1,896 yearling Chinook salmon and 1,888 juvenile steelhead. During the summer study period, we radio-tagged and released 1,919 subyearling Chinook salmon. All fish were tagged using gastric techniques to implant transmitters weighing 1.58 g for yearling Chinook salmon, 1.93 g for juvenile steelhead, and 0.96 g for subyearling Chinook salmon. Minimum fish sizes were based on a 6.5% tag:fish weight ratio, and the size of tagged fish represented about 91%, 100%, and 17% of the population, respectively for yearling Chinook salmon, juvenile steelhead, and subyearling Chinook salmon. About 60% of radio-tagged fish were released 10 km upstream of McNary Dam at Hat Rock State Park, Oregon, with the remainder released as control groups 400 m downstream of the dam.

PUTATIVE ADVERSE OUTCOME PATHWAY FOR INHIBITON ...

EPA Pesticide Factsheets

The adverse outcome pathway (AOP) provides a framework for organizing knowledge to define links between a molecular initiating event (MIE) and an adverse outcome (AO) occurring at a higher level of biological organization, such as the individual or population. The AOP framework proceeds from a general (e.g., not chemical specific) molecular mode of action, designated as a MIE, through stepwise changes in biological status, defined as key events (KEs), to a final AO that can be used in risk assessment. Because aromatase-inhibiting pharmaceuticals are widely used to treat breast cancer patients, we explored the unintended consequences that might occur in fish exposed to these chemicals through wastewater discharge into the aquatic environment. Unlike mammals, fish have two isoforms of aromatase, one that predominates in the ovary (cyp19a1a) and a second (cyp19a1b) that prevails in the brain. Aromatase activity in fish brain can be 100 to 1000 times that in mammals and is associated with reproduction. We have developed a putative AOP for inhibition of brain aromatase in fish leading to reproductive dysfunction based on review of relevant literature and reproductive experiments with the marine fish cunner (Tautogolabrus adspersus) exposed to aromatase-inhibiting pharmaceuticals in the laboratory. The first KE in this AOP is a decrease in brain aromatase activity due to exposure to an aromatase inhibitor. KEs then progress through subsequent steps including decreas

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.

Aquatic disposal field investigations Galveston, Texas, offshore disposal site. Evaluative summary. Final report

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

Wright, T.D.; Mathis, D.B.; Brannon, J.M.

This study was part of an investigation to determine the environmental effects of offshore dredged material disposal at Galveston, Texas. The biological portion of the study was conducted in two phases: a pilot survey of the dredged material disposal site (DMDS) to determine the areal distribution of the biota and sediments; and an experimental study to assess the effect of dredged material disposal on the biota at selected sites in the DMDS. Three experimental sites were investigated: a sandy bottom that received sand, shell, and silt-clay dredged material; a muddy bottom that received sand and shell dredged material; and amore » muddy bottom that received silt-clay dredged material. The magnitude of the effect on the benthic populations could not be accurately assessed because adequate predisposal data on natural sediment and benthic population changes were not available. Dredged material deposits had no apparent effect on feeding habits of fish or on the distribution of nekton, although some nektonic species may have congregated in the turbid water following dredged material disposal. Zooplankton and phytoplankton studies detected no population changes during disposal that could not have been due to sampling error. It is probable that sudden abiotic changes and commercial fishing activities cause more destruction of biota than dredging-related activities.« less

Linking habitat mosaics and connectivity in a coral reef seascape.

PubMed

McMahon, Kelton W; Berumen, Michael L; Thorrold, Simon R

2012-09-18

Tropical marine ecosystems are under mounting anthropogenic pressure from overfishing and habitat destruction, leading to declines in their structure and function on a global scale. Although maintaining connectivity among habitats within a seascape is necessary for preserving population resistance and resilience, quantifying movements of individuals within seascapes remains challenging. Traditional methods of identifying and valuing potential coral reef fish nursery habitats are indirect, often relying on visual surveys of abundance and correlations of size and biomass among habitats. We used compound-specific stable isotope analyses to determine movement patterns of commercially important fish populations within a coral reef seascape. This approach allowed us to quantify the relative contributions of individuals from inshore nurseries to reef populations and identify migration corridors among important habitats. Our results provided direct measurements of remarkable migrations by juvenile snapper of over 30 km, between nurseries and reefs. We also found significant plasticity in juvenile nursery residency. Although a majority of individuals on coastal reefs had used seagrass nurseries as juveniles, many adults on oceanic reefs had settled directly into reef habitats. Moreover, seascape configuration played a critical but heretofore unrecognized role in determining connectivity among habitats. Finally, our approach provides key quantitative data necessary to estimate the value of distinctive habitats to ecosystem services provided by seascapes.

Modelling the effects of stranding on the Atlantic salmon population in the Dale River, Norway.

PubMed

Sauterleute, Julian F; Hedger, Richard D; Hauer, Christoph; Pulg, Ulrich; Skoglund, Helge; Sundt-Hansen, Line E; Bakken, Tor Haakon; Ugedal, Ola

2016-12-15

Rapid dewatering in rivers as a consequence of hydropower operations may cause stranding of juvenile fish and have a negative impact on fish populations. We implemented stranding into an Atlantic salmon population model in order to evaluate long-term effects on the population in the Dale River, Western Norway. Furthermore, we assessed the sensitivity of the stranding model to dewatered area in comparison to biological parameters, and compared different methods for calculating wetted area, the main abiotic input parameter to the population model. Five scenarios were simulated dependent on fish life-stage, season and light level. Our simulation results showed largest negative effect on the population abundance for hydropeaking during winter daylight. Salmon smolt production had highest sensitivity to the stranding mortality of older juvenile fish, suggesting that stranding of fish at these life-stages is likely to have greater population impacts than that of earlier life-stages. Downstream retention effects on the ramping velocity were found to be negligible in the stranding model, but are suggested to be important in the context of mitigation measure design. Copyright © 2016 Elsevier B.V. All rights reserved.

Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef

PubMed Central

Valdivia, Abel; Cox, Courtney E.; Silbiger, Nyssa J.; Bruno, John F.

2017-01-01

Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0–10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations. PMID:28560093

Invasive lionfish had no measurable effect on prey fish community structure across the Belizean Barrier Reef.

PubMed

Hackerott, Serena; Valdivia, Abel; Cox, Courtney E; Silbiger, Nyssa J; Bruno, John F

2017-01-01

Invasive lionfish are assumed to significantly affect Caribbean reef fish communities. However, evidence of lionfish effects on native reef fishes is based on uncontrolled observational studies or small-scale, unrepresentative experiments, with findings ranging from no effect to large effects on prey density and richness. Moreover, whether lionfish affect populations and communities of native reef fishes at larger, management-relevant scales is unknown. The purpose of this study was to assess the effects of lionfish on coral reef prey fish communities in a natural complex reef system. We quantified lionfish and the density, richness, and composition of native prey fishes (0-10 cm total length) at sixteen reefs along ∼250 km of the Belize Barrier Reef from 2009 to 2013. Lionfish invaded our study sites during this four-year longitudinal study, thus our sampling included fish community structure before and after our sites were invaded, i.e., we employed a modified BACI design. We found no evidence that lionfish measurably affected the density, richness, or composition of prey fishes. It is possible that higher lionfish densities are necessary to detect an effect of lionfish on prey populations at this relatively large spatial scale. Alternatively, negative effects of lionfish on prey could be small, essentially undetectable, and ecologically insignificant at our study sites. Other factors that influence the dynamics of reef fish populations including reef complexity, resource availability, recruitment, predation, and fishing could swamp any effects of lionfish on prey populations.

Fish Consumption in Connecticut, Florida, Minnesota, and North Dakota (Final Report)

EPA Science Inventory

In August 2013, EPA announced the availability of the final report,Fish Consumption in Connecticut, Florida, Minnesota, and North Dakota. Many state and local health agencies throughout the United States conduct area-specific surveys that monitor and evaluate contaminant ...

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.

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.

Geographical variation in sound production in the anemonefish Amphiprion akallopisos

PubMed Central

Parmentier, E; Lagardère, J.P; Vandewalle, P; Fine, M.L

2005-01-01

Because of pelagic-larval dispersal, coral-reef fishes are distributed widely with minimal genetic differentiation between populations. Amphiprion akallopisos, a clownfish that uses sound production to defend its anemone territory, has a wide but disjunct distribution in the Indian Ocean. We compared sounds produced by these fishes from populations in Madagascar and Indonesia, a distance of 6500 km. Differentiation of agonistic calls into distinct types indicates a complexity not previously recorded in fishes' acoustic communication. Moreover, various acoustic parameters, including peak frequency, pulse duration, number of peaks per pulse, differed between the two populations. The geographic comparison is the first to demonstrate ‘dialects’ in a marine fish species, and these differences in sound parameters suggest genetic divergence between these two populations. These results highlight the possible approach for investigating the role of sounds in fish behaviour in reproductive divergence and speciation. PMID:16087425

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 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.

Simulating mechanisms for dispersal, production and stranding of small forage fish in temporary wetland habitats

USGS Publications Warehouse

Yurek, Simeon; DeAngelis, Donald L.; Trexler, Joel C.; Jopp, Fred; Donalson, Douglas D.

2013-01-01

Movement strategies of small forage fish (<8 cm total length) between temporary and permanent wetland habitats affect their overall population growth and biomass concentrations, i.e., availability to predators. These fish are often the key energy link between primary producers and top predators, such as wading birds, which require high concentrations of stranded fish in accessible depths. Expansion and contraction of seasonal wetlands induce a sequential alternation between rapid biomass growth and concentration, creating the conditions for local stranding of small fish as they move in response to varying water levels. To better understand how landscape topography, hydrology, and fish behavior interact to create high densities of stranded fish, we first simulated population dynamics of small fish, within a dynamic food web, with different traits for movement strategy and growth rate, across an artificial, spatially explicit, heterogeneous, two-dimensional marsh slough landscape, using hydrologic variability as the driver for movement. Model output showed that fish with the highest tendency to invade newly flooded marsh areas built up the largest populations over long time periods with stable hydrologic patterns. A higher probability to become stranded had negative effects on long-term population size, and offset the contribution of that species to stranded biomass. The model was next applied to the topography of a 10 km × 10 km area of Everglades landscape. The details of the topography were highly important in channeling fish movements and creating spatiotemporal patterns of fish movement and stranding. This output provides data that can be compared in the future with observed locations of fish biomass concentrations, or such surrogates as phosphorus ‘hotspots’ in the marsh.

Behavioural responses to human-induced change: Why fishing should not be ignored.

PubMed

Diaz Pauli, Beatriz; Sih, Andrew

2017-03-01

Change in behaviour is usually the first response to human-induced environmental change and key for determining whether a species adapts to environmental change or becomes maladapted. Thus, understanding the behavioural response to human-induced changes is crucial in the interplay between ecology, evolution, conservation and management. Yet the behavioural response to fishing activities has been largely ignored. We review studies contrasting how fish behaviour affects catch by passive (e.g., long lines, angling) versus active gears (e.g., trawls, seines). We show that fishing not only targets certain behaviours, but it leads to a multitrait response including behavioural, physiological and life-history traits with population, community and ecosystem consequences. Fisheries-driven change (plastic or evolutionary) of fish behaviour and its correlated traits could impact fish populations well beyond their survival per se , affecting predation risk, foraging behaviour, dispersal, parental care, etc., and hence numerous ecological issues including population dynamics and trophic cascades . In particular, we discuss implications of behavioural responses to fishing for fisheries management and population resilience. More research on these topics, however, is needed to draw general conclusions, and we suggest fruitful directions for future studies.

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.

Final Independent External Peer Review Report for the Intake Diversion Dam Modification Lower Yellowstone Project, Montana Draft Supplement to the 26 April 2010 Environmental Assessment and Appendices

DTIC Science & Technology

2013-02-08

Fish and Wildlife Service WRDA Water Resources Development Act Intake Project IEPR Final IEPR Report February 8, 2013 x... Wildlife Service (USFWS), Natural Resources Conservation Service (NRCS), Montana Department of Environmental Quality, The Nature Conservancy...30% design features and channel entrance and exit pre-appraisal study to provide fish passage around Intake Dam, Montana. U.S. Fish and Wildlife

78 FR 32996 - Western Pacific Fisheries; Fishing in the Marianas Trench, Pacific Remote Islands, and Rose Atoll...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-03

... consider the use of modern gear integral to both maintaining traditional indigenous fishing in the... traditional indigenous fishing practices. The Council recommended incorporating the Proclamations' fishery... traditional indigenous fishing practices. This final rule implements the Council's recommendations. Consistent...

Age, growth, and mortality of introduced flathead catfish in Atlantic rivers and a review of other populations

USGS Publications Warehouse

Kwak, T.J.; Pine, William E.; Waters, D.S.

2006-01-01

Knowledge of individual growth and mortality rates of an introduced fish population is required to determine the success and degree of establishment as well as to predict the fish's impact on native fauna. The age and growth of flathead catfish Pylodictis olivaris have been studied extensively in the species' native and introduced ranges, and estimates have varied widely. We quantified individual growth rates and age structure of three introduced flathead catfish populations in North Carolina's Atlantic slope rivers using sagittal otoliths, determined trends in growth rates over time, compared these estimates among rivers in native and introduced ranges, and determined total mortality rates for each population. Growth was significantly faster in the Northeast Cape Fear River (NECFR) than in the Lumber and Neuse rivers. Fish in the NECFR grew to a total length of 700 mm by age 7, whereas fish in the Neuse and Lumber river populations reached this length by 8 and 10 years, respectively. The growth rates of fish in all three rivers were consistently higher than those of native riverine populations, similar to those of native reservoir populations, and slower than those of other introduced riverine populations. In general, recent cohorts (1998-2001 year-classes) in these three rivers exhibited slower growth among all ages than did cohorts previous to the 1998 year-class. The annual total mortality rate was similar among the three rivers, ranging from 0.16 to 0.20. These mortality estimates are considerably lower than those from the Missouri and Mississippi rivers, suggesting relatively low fishing mortality for these introduced populations. Overall, flathead catfish populations in reservoirs grow faster than those in rivers, the growth rates of introduced populations exceed those of native populations, and eastern United States populations grow faster than those in western states. Such trends constitute critical information for understanding and managing local populations.

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...

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.

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.

Migration and spawning of radio-tagged zulega Prochilodus argenteus in a dammed Brazilian river

USGS Publications Warehouse

Godinho, Alexandre L.; Kynard, B.

2006-01-01

It is difficult for agencies to evaluate the impacts of the many planned dams on Sa??o Francisco River, Brazil, migratory fishes because fish migrations are poorly known. We conducted a study on zulega Prochilodus argenteus, an important commercial and recreational fish in the Sa??o Francisco River, to identify migrations and spawning areas and to determine linear home range. During two spawning seasons (2001-2003), we radio-tagged fish in three main-stem reaches downstream of Tre??s Marias Dam (TMD), located at river kilometer (rkm) 2,109. We tagged 10 fish at Tre??s Marias (TM), which is 5 km downstream of TMD; 12 fish at Pontal, which is 28 km downstream of TMD and which includes the mouth of the Abaete?? River, and 10 fish at Cilga, which is 45 km downstream of TMD. Late-stage (ripe) adults tagged in each area during the spawning season remained at or near the tagging site, except for four Cilga fish that went to Pontal and probably spawned. The Pontal area at the Abaete?? River mouth was the most important spawning site we found. Prespawning fish moved back and forth between main-stem staging areas upstream of the Abaete?? River mouth and Pontal for short visits. These multiple visits were probably needed as ripe fish waited for spawning cues from a flooding Abaete?? River. Some fish homed to prespaw ning staging areas, spawning areas, and nonspawning areas. The migratory style of zulega was dualistic, with resident and migratory fish. Total linear home range was also dualistic, with small (<26-km) and large (53-127-km) ranges. The locations of spawning areas and home ranges suggest that the Pontal group (which includes Cilga fish) is one population that occupies about 110 km. The Pontal population overlaps a short distance with a population located downstream of Cilga. Movements of late-stage TM adults suggest that the TM group is a separate population, possibly with connections to populations upstream of TMD. ?? Copyright by the American Fisheries Society 2006.

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 sampling methods.

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

Estimating the hatchery fraction of a natural population: a Bayesian approach

USGS Publications Warehouse

Barber, Jarrett J.; Gerow, Kenneth G.; Connolly, Patrick J.; Singh, Sarabdeep

2011-01-01

There is strong and growing interest in estimating the proportion of hatchery fish that are in a natural population (the hatchery fraction). In a sample of fish from the relevant population, some are observed to be marked, indicating their origin as hatchery fish. The observed proportion of marked fish is usually less than the actual hatchery fraction, since the observed proportion is determined by the proportion originally marked, differential survival (usually lower) of marked fish relative to unmarked hatchery fish, and rates of mark retention and detection. Bayesian methods can work well in a setting such as this, in which empirical data are limited but for which there may be considerable expert judgment regarding these values. We explored a Bayesian estimation of the hatchery fraction using Monte Carlo–Markov chain methods. Based on our findings, we created an interactive Excel tool to implement the algorithm, which we have made available for free.

Using Tournament Angler Data to Rapidly Assess the Invasion Status of Alien Sport Fishes (Micropterus spp.) in Southern Africa.

PubMed

Hargrove, John S; Weyl, Olaf L F; Allen, Micheal S; Deacon, Neil R

2015-01-01

Fishes are one of the most commonly introduced aquatic taxa worldwide, and invasive fish species pose threats to biodiversity and ecosystem function in recipient waters. Considerable research efforts have focused on predicting the invasibility of different fish taxa; however, accurate records detailing the establishment and spread of invasive fishes are lacking for large numbers of fish around the globe. In response to these data limitations, a low-cost method of cataloging and quantifying the temporal and spatial status of fish invasions was explored. Specifically, angler catch data derived from competitive bass angling tournaments was used to document the distribution of 66 non-native populations of black bass (Micropterus spp.) in southern Africa. Additionally, catch data from standardized tournament events were used to assess the abundance and growth of non-native bass populations in southern Africa relative to their native distribution (southern and eastern United States). Differences in metrics of catch per unit effort (average number of fish retained per angler per day), daily bag weights (the average weight of fish retained per angler), and average fish weight were assessed using catch data from 14,890 angler days of tournament fishing (11,045 days from South Africa and Zimbabwe; 3,845 days from the United States). No significant differences were found between catch rates, average daily bag weight, or the average fish weight between countries, suggesting that bass populations in southern Africa reach comparable sizes and numbers relative to waters in their native distribution. Given the minimal cost associated with data collection (i.e. records are collected by tournament organizers), the standardized nature of the events, and consistent bias (i.e. selection for the biggest fish in a population), the use of angler catch data represents a novel approach to infer the status and distribution of invasive sport fish.

Using Tournament Angler Data to Rapidly Assess the Invasion Status of Alien Sport Fishes (Micropterus spp.) in Southern Africa

PubMed Central

Hargrove, John S.; Weyl, Olaf L. F.; Allen, Micheal S.; Deacon, Neil R.

2015-01-01

Fishes are one of the most commonly introduced aquatic taxa worldwide, and invasive fish species pose threats to biodiversity and ecosystem function in recipient waters. Considerable research efforts have focused on predicting the invasibility of different fish taxa; however, accurate records detailing the establishment and spread of invasive fishes are lacking for large numbers of fish around the globe. In response to these data limitations, a low-cost method of cataloging and quantifying the temporal and spatial status of fish invasions was explored. Specifically, angler catch data derived from competitive bass angling tournaments was used to document the distribution of 66 non-native populations of black bass (Micropterus spp.) in southern Africa. Additionally, catch data from standardized tournament events were used to assess the abundance and growth of non-native bass populations in southern Africa relative to their native distribution (southern and eastern United States). Differences in metrics of catch per unit effort (average number of fish retained per angler per day), daily bag weights (the average weight of fish retained per angler), and average fish weight were assessed using catch data from 14,890 angler days of tournament fishing (11,045 days from South Africa and Zimbabwe; 3,845 days from the United States). No significant differences were found between catch rates, average daily bag weight, or the average fish weight between countries, suggesting that bass populations in southern Africa reach comparable sizes and numbers relative to waters in their native distribution. Given the minimal cost associated with data collection (i.e. records are collected by tournament organizers), the standardized nature of the events, and consistent bias (i.e. selection for the biggest fish in a population), the use of angler catch data represents a novel approach to infer the status and distribution of invasive sport fish. PMID:26047487

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...

76 FR 59304 - 2011-2012 Refuge-Specific Hunting and Sport Fishing Regulations; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-26

...-0038; 93270-1265-0000-4A] RIN 1018-AX54 2011-2012 Refuge-Specific Hunting and Sport Fishing Regulations... our regulations concerning hunting and sport fishing programs at national wildlife refuges... part 32 concerning hunting and sport fishing programs at national wildlife refuges. The final rule...

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

From forager tracks to prey distributions: an application to tuna vessel monitoring systems (VMS).

PubMed

Walker, Emily; Rivoirard, Jacques; Gaspar, Philippe; Bez, Nicolas

2015-04-01

In the open ocean, movements of migratory fish populations are typically surveyed using tagging methods that are subject to low sample sizes for archive tags, except for a few notable examples, and poor temporal resolution for conventional tags. Alternatively, one can infer patterns of movement of migratory fish by tracking movements of their predators, i.e., fishing vessels, whose navigational systems (e.g., GPS) provide accurate and frequent VMS (vessel monitoring system) records of movement in pursuit of prey. In this paper, we develop a state-space model that infers the foraging activities of fishing vessels from their tracks. Second, we link foraging activities to probabilities of tuna presence. Finally, using multivariate geostatistical interpolation (cokriging) we map the probability of tuna presence together with their estimation variances and produce a time series of indices of abundance. While the segmentation of the trajectories is validated by observers' data, the present VMS-index is compared to catch rate and proved to be useful for management perspectives. The approach reported in this manuscript extends beyond the case study considered. It can be applied to any foragers that engage in an attempt of capture when they see prey and for whom this attempt is linked to a tractable change in behavior.

Determinants of mercury contamination in viperine snakes, Natrix maura, in Western Europe.

PubMed

Lemaire, Jérémy; Bustamante, Paco; Olivier, Anthony; Lourdais, Olivier; Michaud, Bruno; Boissinot, Alexandre; Galán, Pedro; Brischoux, François

2018-04-13

The effects of Hg contamination are presumably widespread across the components of aquatic ecosystems, but investigations have been mainly focused on freshwater fish, because this biota represents a major source of Hg for human populations. Yet, the possible bioaccumulation of Hg on other freshwater meso- and apex-predators (e.g., amphibians, reptiles) has been largely overlooked, especially in Western Europe. In this study, the determinants of Hg concentrations were assessed for the viperine snake (Natrix maura) across 6 populations (>130 individuals sampled in 2016 and 2017) in France and Spain. Specifically, body size, sex, and diet were compared with Hg concentrations measured in ventral scales. Overall, N. maura accumulated Hg in their scales. Sex did not seem to influence Hg concentrations in this species. Significant differences in Hg concentrations were observed between study sites, and these differences were likely to be mediated by site-specific diet. Frog-eating individuals were characterized not only by lower mean values of Hg (0.194±0.018μg·g -1 versus 0.386±0.032μg·g -1 for piscivorous individuals), but also by weaker slopes of the body size-Hg relationship as compared to fish-eating snakes, suggesting strong differences in accumulation rates due to food resources. Importantly, the highest slope of the body size-Hg relationship and the highest values of Hg were found in individuals foraging on trout raised by a fish farm, suggesting that fish farming may contribute to Hg contamination in inland freshwater systems. Finally, our results are compared with data on Hg concentrations in other species of aquatic snakes, in order to provide a comparative point for future studies. Copyright © 2018 Elsevier B.V. All rights reserved.

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

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.

Tracking pollutants in dietary fish oil: From ocean to table.

PubMed

Sun, Sheng-Xiang; Hua, Xue-Ming; Deng, Yun-Yun; Zhang, Yun-Ni; Li, Jia-Min; Wu, Zhao; Limbu, Samwel Mchele; Lu, Da-Sheng; Yin, Hao-Wen; Wang, Guo-Quan; Waagbø, Rune; Livar, Frøyland; Zhang, Mei-Ling; Du, Zhen-Yu

2018-05-16

Dietary fish oil used in aquafeed transfers marine pollutants to farmed fish. However, the entire transfer route of marine pollutants in dietary fish oil from ocean to table fish has not been tracked quantitatively. To track the entire transfer route of marine pollutants from wild fish to farmed fish through dietary fish oil and evaluate the related human health risks, we obtained crude and refined fish oils originating from the same batch of wild ocean anchovy and prepared fish oil-containing purified aquafeeds to feed omnivorous lean Nile tilapia and carnivorous fatty yellow catfish for eight weeks. The potential human health risk of consumption of these fish was evaluated. Marine persistent organic pollutants (POPs) were concentrated in fish oil, but were largely removed by the refining process, particularly dioxins and polychlorinated biphenyls (PCBs). The differences in the POP concentrations between crude and refined fish oils were retained in the fillets of the farmed fish. Fillets fat content and fish growth were positively and negatively correlated to the final POPs deposition in fillets, respectively. The retention rates of marine POPs in the final fillets through fish oil-contained aquafeeds were 1.3%-5.2%, and were correlated with the POPs concentrations in feeds and fillets, feed utilization and carcass ratios. The dietary crude fish oil-contained aquafeeds are a higher hazard ratio to consumers. Prohibiting the use of crude fish oil in aquafeed and improving growth and feed efficiency in farmed fish are promising strategies to reduce health risks originating from marine POPs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Dynamics and management of stage-structured fish stocks.

PubMed

Meng, Xinzhu; Lundström, Niklas L P; Bodin, Mats; Brännström, Åke

2013-01-01

With increasing fishing pressures having brought several stocks to the brink of collapse, there is a need for developing efficient harvesting methods that account for factors beyond merely yield or profit. We consider the dynamics and management of a stage-structured fish stock. Our work is based on a consumer-resource model which De Roos et al. (in Theor. Popul. Biol. 73, 47-62, 2008) have derived as an approximation of a physiologically-structured counterpart. First, we rigorously prove the existence of steady states in both models, that the models share the same steady states, and that there exists at most one positive steady state. Furthermore, we carry out numerical investigations which suggest that a steady state is globally stable if it is locally stable. Second, we consider multiobjective harvesting strategies which account for yield, profit, and the recovery potential of the fish stock. The recovery potential is a measure of how quickly a fish stock can recover from a major disturbance and serves as an indication of the extinction risk associated with a harvesting strategy. Our analysis reveals that a small reduction in yield or profit allows for a disproportional increase in recovery potential. We also show that there exists a harvesting strategy with yield close to the maximum sustainable yield (MSY) and profit close to that associated with the maximum economic yield (MEY). In offering a good compromise between MSY and MEY, we believe that this harvesting strategy is preferable in most instances. Third, we consider the impact of harvesting on population size structure and analytically determine the most and least harmful harvesting strategies. We conclude that the most harmful harvesting strategy consists of harvesting both adults and juveniles, while harvesting only adults is the least harmful strategy. Finally, we find that a high percentage of juvenile biomass indicates elevated extinction risk and might therefore serve as an early-warning signal of impending stock collapse.

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

Angler harvest, hatchery return, and tributary stray rates of recycled adult summer steelhead Oncorhynchus mykiss in the Cowlitz River, Washington

USGS Publications Warehouse

Kock, Tobias J.; Perry, Russell W.; Gleizes, Chris; Dammers, Wolf; Liedtke, Theresa L.

2016-01-01

Hatchery ‘recycling’ programs have been used to increase angling opportunities by re-releasing fish into a river after they returned to a hatchery or fish trap. Recycling is intended to increase opportunities for fishermen, but this strategy could affect wild fish populations if some recycled fish remain in the river and interact with wild fish populations. To quantify hatchery return and angler harvest rates of recycled steelhead, we conducted a 2-year study on the Cowlitz River, Washington. A total of 1051 steelhead were recycled, including 218 fish that were radio-tagged. Fates of recycled steelhead were similar between years: 48.4% returned to the hatchery, 19.2% were reported captured by anglers, and 32.4% remained in the river. A multistate model quantified the effects of covariates on hatchery return and angler harvest rates, which were positively affected by river discharge and negatively affected by time since release. However, hatchery return rates increased and angler harvest rates decreased during periods of increasing discharge. A total of 21.1% (46 fish) of the radio-tagged steelhead failed to return to the hatchery or be reported by anglers, but nearly half of those fish (20 fish) appeared to be harvested and not reported. The remaining tagged fish (11.9% of the radio-tagged population) were monitored into the spawning period, but only five fish (2.3% of the radio-tagged population) entered tributaries where wild steelhead spawning occurs. Future research focused on straying behaviour, and spawning success of recycled steelhead may further advance the understanding of the effects of recycling as a management strategy.

Fishing-induced changes in adult length are mediated by skipped-spawning.

PubMed

Wang, Hui-Yu; Chen, Ying-Shiuan; Hsu, Chien-Chung; Shen, Sheng-Feng

2017-01-01

Elucidating fishing effects on fish population dynamics is a critical step toward sustainable fisheries management. Despite previous studies that have suggested age or size truncation in exploited fish populations, other aspects of fishing effects on population demography, e.g., via altering life histories and density, have received less attention. Here, we investigated the fishing effects altering adult demography via shifting reproductive trade-offs in the iconic, overexploited, Pacific bluefin tuna Thunnus orientalis. We found that, contrary to our expectation, mean lengths of catch increased over time in longline fisheries. On the other hand, mean catch lengths for purse seine fisheries did not show such increasing trends. We hypothesized that the size-dependent energetic cost of the spawning migration and elevated fishing mortality on the spawning grounds potentially drive size-dependent skipped spawning for adult tuna, mediating the observed changes in the catch lengths. Using eco-genetic individual-based modeling, we demonstrated that fishing-induced evolution of skipped spawning and size truncation interacted to shape the observed temporal changes in mean catch lengths for tuna. Skipped spawning of the small adults led to increased mean catch lengths for the longline fisheries, while truncation of small adults by the purse seines could offset such a pattern. Our results highlight the eco-evolutionary dynamics of fishing effects on population demography and caution against using demographic traits as a basis for fisheries management of the Pacific bluefin tuna as well as other migratory species. © 2016 by the Ecological Society of America.

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 abundances and size structures present before golden alga. Received August 26, 2011; accepted November 25, 2012

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 upper end of Condor Canyon, where a tributary known as Kill Wash, and several springs, contribute flow and moderate high and low water temperature. Kill Wash and the area around its confluence with Meadow Valley Wash appeared important for spawning of all three native species. Detections of PIT-tagged fish indicated that there were substantial movements to this area during the spring. Our surveys included about 700 m of Meadow Valley Wash upstream of Kill Wash. A small falls about 2 m high was about 560 m upstream of Kill Wash. This falls is likely a barrier to upstream fish movement at most flows. Populations of all three native species were found upstream of this small falls. Age-0 fish of all three species were present, indicating successful spawning. The maximum upstream extent of native fish within Meadow Valley Wash was not determined. Our surveys included about 700 m of Meadow Valley Wash upstream of Kill Wash. A small falls about 2 m high was about 560 m upstream of Kill Wash. This falls is likely a barrier to upstream fish movement at most flows. Populations of all three native species were found upstream of this small falls. Age-0 fish of all three species were present, indicating successful spawning. The maximum upstream extent of native fish within Meadow Valley Wash was not determined. A population of non-native rainbow trout (Oncorhynchus mykiss) was found within the 2,000 m of stream immediately downstream of Delmue Falls. Non-native crayfish were very common both upstream and downstream of Delmue Falls. We were not able to quantify crayfish populations, but they compose a significant portion of the biomass of aquatic species in Condor Canyon. There were some distinctive habitat features that may have favored native fish upstream of Delmue Falls. Upstream of the falls, water temperatures were moderated by inputs from springs, turbidity was lower, pool habitat was more prevalent, substrate heterogeneity was higher, and there was less fine sediment than

Linking habitat structure to life history strategy: Insights from a Mediterranean killifish

NASA Astrophysics Data System (ADS)

Cavraro, Francesco; Daouti, Irini; Leonardos, Ioannis; Torricelli, Patrizia; Malavasi, Stefano

2014-01-01

Modern theories of life history evolution deal with finding links between environmental factors, demographic structure of animal populations and the optimal life history strategy. Small-sized teleost fish, occurring in fragmented populations under contrasting environments, have been widely used as study models to investigate these issues. In the present study, the Mediterranean killifish Aphanius fasciatus was used to investigate the relationships between some habitat features and life history strategy. We selected four sites in the Venice lagoon inhabited by this species, exhibiting different combinations of two factors: overall adult mortality, related to intertidal water coverage and a consequent higher level of predator exposure, and the level of sediment organic matter, as indicator of habitat trophic richness. Results showed that these were the two most important factors influencing demography and life history traits in the four sites. Fish from salt marshes with high predator pressure were smaller and produced a higher number of eggs, whereas bigger fish and a lower reproductive investment were found in the two closed, not tidally influenced habitats. Habitat richness was positively related with population density, but negatively related with growth rate. In particular the synergy between high resources and low predation level was found to be important in shaping peculiar life history traits. Results were discussed in the light of the interactions between selective demographic forces acting differentially on age/size classes, such as predation, and habitat trophic richness that may represent an important energetic constraint on life history traits. The importance to link habitat productivity and morphology to demographic factors for a better understanding of the evolution of life history strategy under contrasting environments was finally suggested.

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

Population dynamics of the sand shiner (notropis stramineus) in non-wadeable rivers of Iowa

USGS Publications Warehouse

Smith, C.D.; Neebling, T.E.; Quist, M.C.

2010-01-01

The sand shiner (Notropis stramineus) is a common cyprinid found throughout the Great Plains region of North America that plays an important ecological role in aquatic systems. This study was conducted to describe population dynamics of sand shiners including age structure, growth, mortality, and recruitment variability in 15 non-wadeable rivers in Iowa. Fish were collected during June-August (2007-2008) using a modified Missouri trawl, a seine, and boat-mounted electrofishing. Scales were removed for age and growth analysis. A total of 3,443 fish was sampled from 15 populations across Iowa, of which 676 were aged. Iowa's sand shiner populations consisted primarily of age-1 fish (53% of all fish sampled), followed by age-2 fish (30%), age-0 fish (15%), and age-3 fish (2%). Sand shiners grew an average of 38.5 mm (SE = 5.7) during their first year, 13.8 mm (4.5) during their second year, and 9.0 mm (6.9) during their third year. Total annual mortality varied from 35.0% to 92.3% among populations with a mean of 77.9% (0.2). Incremental mortality rates were 84.5% (0.2) between age 1 and age 2, and 92.0% (0.1) between age 2 and age 3. Recruitment was highly variable, as indicated by a mean recruitment variation index of-0.12 (0.54). Overall, the sand shiner was characterized by relatively low mean age, fast growth, high mortality, and high recruitment variability. Indices of sand shiner population dynamics were poorly correlated with habitat characteristics.

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.

Small-scale fisheries, population dynamics, and resource use in Africa: the case of Moree, Ghana.

PubMed

Marquette, Catherine M; Koranteng, Kwame A; Overå, Ragnhild; Aryeetey, Ellen Bortei-Doku

2002-06-01

We consider population dynamics and sustainable use and development of fishery resources in Moree, a small-scale fishing and coastal community of 20,000 people in the Central Region of Ghana near Cape Coast. Moree suggests that relationships between population dynamics and fishery resources are more complex than the concept of Malthusian overfishing implies. Reasons include changing biophysical characteristics of the upwelling system along the coast of West Africa; qualitative as well as quantitative changes in fishing activity throughout the year; the market nature of fishing activity and nonlocal demands for fish; regular fishery migration; and institutions regulating fishery resource access at home and at migration destinations. Population and resource relationships in Moree may be the effects of fishery resource and economic changes on migration rather than population pressure on fishery resources. Fisheries management policies must take into account processes that lie beyond the influence of local fishermen.

Fatal Asphyxiation in Bottlenose Dolphins (Tursiops truncatus) from the Indian River Lagoon.

PubMed

Stolen, Megan; St Leger, Judy; Durden, Wendy Noke; Mazza, Teresa; Nilson, Erika

2013-01-01

Multiple single case reports of asphyxiation in dolphins caused by fish lodged in the esophagus exist. However, the significance of this cause of mortality in a single population has not been documented. We performed a retrospective evaluation of pathology records from stranded bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon to evaluate the impact of this cause of death on this population. From 1997 to 2011, asphyxiation due to choking was identified as the cause of death in 14 of 350 cases (4%). Sampling of an unrelated but adjacent population over this same period yielded 186 necropsy cases of bottlenose dolphins with no cases of asphyxiation. Asphyxiated animals presented with a fish lodged in the cranial esophagus associated with a dislocated and obstructed or compressed larynx. There was no clear sex predilection. Affected animals included 12 adults and two juveniles. The fish species involved included sheepshead, black chin tilapia and striped mojarra. In five cases, recreational fishing gear was also present. Cetacean choking is related to selection of prey fish species with strong dorsal spines and may be secondarily associated with fish attached to fishing gear. Prey abundance and dolphin behavior may influence these selections. Environmental alterations leading to changes in prey availability or increased interactions with fishing gear may change the significance of fatal choking in dolphin populations.

Small Marine Protected Areas in Fiji Provide Refuge for Reef Fish Assemblages, Feeding Groups, and Corals.

PubMed

Bonaldo, Roberta M; Pires, Mathias M; Guimarães, Paulo Roberto; Hoey, Andrew S; Hay, Mark E

2017-01-01

The establishment of no-take marine protected areas (MPAs) on coral reefs is a common management strategy for conserving the diversity, abundance, and biomass of reef organisms. Generally, well-managed and enforced MPAs can increase or maintain the diversity and function of the enclosed coral reef, with some of the benefits extending to adjacent non-protected reefs. A fundamental question in coral reef conservation is whether these benefits arise within small MPAs (<1 km2), because larval input of reef organisms is largely decoupled from local adult reproduction. We examined the structure of fish assemblages, composition of fish feeding groups, benthic cover, and key ecosystem processes (grazing, macroalgal browsing, and coral replenishment) in three small (0.5-0.8 km2) no-take MPAs and adjacent areas where fisheries are allowed (non-MPAs) on coral reefs in Fiji. The MPAs exhibited greater species richness, density, and biomass of fishes than non-MPAs. Furthermore, MPAs contained a greater abundance and biomass of grazing herbivores and piscivores as well as a greater abundance of cleaners than fished areas. We also found differences in fish associations when foraging, with feeding groups being generally more diverse and having greater biomass within MPAs than adjacent non-MPAs. Grazing by parrotfishes was 3-6 times greater, and macroalgal browsing was 3-5 times greater in MPAs than in non-MPAs. On average, MPAs had 260-280% as much coral cover and only 5-25% as much macroalgal cover as their paired non-MPA sites. Finally, two of the three MPAs had three-fold more coral recruits than adjacent non-MPAs. The results of this study indicate that small MPAs benefit not only populations of reef fishes, but also enhance ecosystem processes that are critical to reef resilience within the MPAs.

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 catch composition, and therefore the benefits of maintaining fish populations at specific densities. © 2018 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Malheur River Wildlife Mitigation Project, Annual Report 2003.

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

Ashley, Paul

Hydropower development within the Columbia and Snake River Basins has significantly affected riparian, riverine, and adjacent upland habitats and the fish and wildlife species dependent upon them. Hydroelectric dams played a major role in the extinction or major loss of both anadromous and resident salmonid populations and altered instream and adjacent upland habitats, water quality, and riparian/riverine function. Hydroelectric facility construction and inundation directly affected fish and wildlife species and habitats. Secondary and tertiary impacts including road construction, urban development, irrigation, and conversion of native habitats to agriculture, due in part to the availability of irrigation water, continue to affectmore » wildlife and fish populations throughout the Columbia and Snake River Basins. Fluctuating water levels resulting from facility operations have created exposed sand, cobble, and/or rock zones. These zones are generally devoid of vegetation with little opportunity to re-establish riparian plant communities. To address the habitat and wildlife losses, the United States Congress in 1980 passed the Pacific Northwest Electric Power Planning and Conservation Act (Act) (P.L. 96-501), which authorized the states of Idaho, Montana, Oregon, and Washington to create the Northwest Power Planning Council (Council). The Act directed the Council to prepare a program in conjunction with federal, state, and tribal wildlife resource authorities to protect, mitigate, and enhance fish and wildlife species affected by the construction, inundation and operation of hydroelectric dams in the Columbia River Basin (NPPC 2000). Under the Columbia Basin Fish and Wildlife Program (Program), the region's fish and wildlife agencies, tribes, non-government organizations (NGOs), and the public propose fish and wildlife projects that address wildlife and fish losses resulting from dam construction and subsequent inundation. As directed by the Council, project proposals are subjected to a rigorous review process prior to receiving final approval. An eleven-member panel of scientists referred to as the Independent Scientific Review Panel (ISRP) examines project proposals. The ISRP recommends project approval based on scientific merit. The Bonneville Power Administration (BPA), the Columbia Basin Fish and Wildlife Authority (CBFWA), Council staff, the U.S. Fish and Wildlife Service (USFWS), the National Oceanic and Atmospheric Administration (NOAA), and subbasin groups also review project proposals to ensure each project meets regional and subbasin goals and objectives. The Program also includes a public involvement component that gives the public an opportunity to provide meaningful input on management proposals. After a thorough review, the Burns Paiute Tribe (BPT) acquired the Malheur River Mitigation Project (Project) with BPA funds to compensate, in part, for the loss of fish and wildlife resources in the Columbia and Snake River Basins and to address a portion of the mitigation goals identified in the Council's Program (NPPC 2000).« less

Sustainability in single-species population models.

PubMed

Quinn, Terrance J; Collie, Jeremy S

2005-01-29

In this paper, we review the concept of sustainability with regard to a single-species, age-structured fish population with density dependence at some stage of its life history. We trace the development of the view of sustainability through four periods. The classical view of sustainability, prevalent in the 1970s and earlier, developed from deterministic production models, in which equilibrium abundance or biomass is derived as a function of fishing mortality. When there is no fishing mortality, the population equilibrates about its carrying capacity. We show that carrying capacity is the result of reproductive and mortality processes and is not a fixed constant unless these processes are constant. There is usually a fishing mortality, F(MSY), which results in MSY, and a higher value, F(ext), for which the population is eventually driven to extinction. For each F between 0 and F(ext), there is a corresponding sustainable population. From this viewpoint, the primary tool for achieving sustainability is the control of fishing mortality. The neoclassical view of sustainability, developed in the 1980s, involved population models with depensation and stochasticity. This view point is in accord with the perception that a population at a low level is susceptible to collapse or to a lack of rebuilding regardless of fishing. Sustainability occurs in a more restricted range from that in the classical view and includes an abundance threshold. A variety of studies has suggested that fishing mortality should not let a population drop below a threshold at 10-20% of carrying capacity. The modern view of sustainability in the 1990s moves further in the direction of precaution. The fishing mortality limit is the former target of F(MSY) (or some proxy), and the target fishing mortality is set lower. This viewpoint further reduces the range of permissible fishing mortalities and resultant desired population sizes. The objective has shifted from optimizing long-term catch to preserving spawning biomass and egg production for the future. The use of discount rates in objective functions involving catch is not a suitable alternative to protecting reproductive value. As we move into the post-modern time period, new definitions of sustainability will attempt to incorporate he economic and social aspects of fisheries and/or ecosystem and habitat requirements. These definitions now involve "warm and fuzzy" notions (healthy ecosystems and fishing communities, the needs of future generations, diverse fish communities) and value judgements of desired outcomes. Additional work is needed to make these definitions operational and to specify quantitative objectives to be achieved. In addition, multiple objectives may be incompatible, so trade-offs in what constitutes sustainability must be made. The advances made under the single-species approach should not be abandoned in the post-modern era, but rather enhanced and combined with new approaches in the multi-species and economic realms.

Sustainability in single-species population models

PubMed Central

Quinn, Terrance J.; Collie, Jeremy S.

2005-01-01

In this paper, we review the concept of sustainability with regard to a single-species, age-structured fish population with density dependence at some stage of its life history. We trace the development of the view of sustainability through four periods. The classical view of sustainability, prevalent in the 1970s and earlier, developed from deterministic production models, in which equilibrium abundance or biomass is derived as a function of fishing mortality. When there is no fishing mortality, the population equilibrates about its carrying capacity. We show that carrying capacity is the result of reproductive and mortality processes and is not a fixed constant unless these processes are constant. There is usually a fishing mortality, FMSY, which results in MSY, and a higher value, Fext, for which the population is eventually driven to extinction. For each F between 0 and Fext, there is a corresponding sustainable population. From this viewpoint, the primary tool for achieving sustainability is the control of fishing mortality. The neoclassical view of sustainability, developed in the 1980s, involved population models with depensation and stochasticity. This viewpoint is in accord with the perception that a population at a low level is susceptible to collapse or to a lack of rebuilding regardless of fishing. Sustainability occurs in a more restricted range from that in the classical view and includes an abundance threshold. A variety of studies has suggested that fishing mortality should not let a population drop below a threshold at 10–20% of carrying capacity. The modern view of sustainability in the 1990s moves further in the direction of precaution. The fishing mortality limit is the former target of FMSY (or some proxy), and the target fishing mortality is set lower. This viewpoint further reduces the range of permissible fishing mortalities and resultant desired population sizes. The objective has shifted from optimizing long-term catch to preserving spawning biomass and egg production for the future. The use of discount rates in objective functions involving catch is not a suitable alternative to protecting reproductive value. As we move into the post-modern time period, new definitions of sustainability will attempt to incorporate the economic and social aspects of fisheries and/or ecosystem and habitat requirements. These definitions now involve ‘warm and fuzzy’ notions (healthy ecosystems and fishing communities, the needs of future generations, diverse fish communities) and value judgements of desired outcomes. Additional work is needed to make these definitions operational and to specify quantitative objectives to be achieved. In addition, multiple objectives may be incompatible, so trade-offs in what constitutes sustainability must be made. The advances made under the single-species approach should not be abandoned in the post-modern era, but rather enhanced and combined with new approaches in the multi-species and economic realms. PMID:15713594

Human activities as a driver of spatial variation in the trophic structure of fish communities on Pacific coral reefs.

PubMed

Ruppert, Jonathan L W; Vigliola, Laurent; Kulbicki, Michel; Labrosse, Pierre; Fortin, Marie-Josée; Meekan, Mark G

2018-01-01

Anthropogenic activities such as land-use change, pollution and fishing impact the trophic structure of coral reef fishes, which can influence ecosystem health and function. Although these impacts may be ubiquitous, they are not consistent across the tropical Pacific Ocean. Using an extensive database of fish biomass sampled using underwater visual transects on coral reefs, we modelled the impact of human activities on food webs at Pacific-wide and regional (1,000s-10,000s km) scales. We found significantly lower biomass of sharks and carnivores, where there were higher densities of human populations (hereafter referred to as human activity); however, these patterns were not spatially consistent as there were significant differences in the trophic structures of fishes among biogeographic regions. Additionally, we found significant changes in the benthic structure of reef environments, notably a decline in coral cover where there was more human activity. Direct human impacts were the strongest in the upper part of the food web, where we found that in a majority of the Pacific, the biomass of reef sharks and carnivores were significantly and negatively associated with human activity. Finally, although human-induced stressors varied in strength and significance throughout the coral reef food web across the Pacific, socioeconomic variables explained more variation in reef fish trophic structure than habitat variables in a majority of the biogeographic regions. Notably, economic development (measured as GDP per capita) did not guarantee healthy reef ecosystems (high coral cover and greater fish biomass). Our results indicate that human activities are significantly shaping patterns of trophic structure of reef fishes in a spatially nonuniform manner across the Pacific Ocean, by altering processes that organize communities in both "top-down" (fishing of predators) and "bottom-up" (degradation of benthic communities) contexts. © 2017 John Wiley & Sons Ltd.

Larval export from marine reserves and the recruitment benefit for fish and fisheries.

PubMed

Harrison, Hugo B; Williamson, David H; Evans, Richard D; Almany, Glenn R; Thorrold, Simon R; Russ, Garry R; Feldheim, Kevin A; van Herwerden, Lynne; Planes, Serge; Srinivasan, Maya; Berumen, Michael L; Jones, Geoffrey P

2012-06-05

Marine reserves, areas closed to all forms of fishing, continue to be advocated and implemented to supplement fisheries and conserve populations. However, although the reproductive potential of important fishery species can dramatically increase inside reserves, the extent to which larval offspring are exported and the relative contribution of reserves to recruitment in fished and protected populations are unknown. Using genetic parentage analyses, we resolve patterns of larval dispersal for two species of exploited coral reef fish within a network of marine reserves on the Great Barrier Reef. In a 1,000 km(2) study area, populations resident in three reserves exported 83% (coral trout, Plectropomus maculatus) and 55% (stripey snapper, Lutjanus carponotatus) of assigned offspring to fished reefs, with the remainder having recruited to natal reserves or other reserves in the region. We estimate that reserves, which account for just 28% of the local reef area, produced approximately half of all juvenile recruitment to both reserve and fished reefs within 30 km. Our results provide compelling evidence that adequately protected reserve networks can make a significant contribution to the replenishment of populations on both reserve and fished reefs at a scale that benefits local stakeholders. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

Fish passage through retrofitted culverts : final report.

DOT National Transportation Integrated Search

2004-11-01

Long term and short term studies of fish movement were conducted at several retrofitted culverts within Oregon. This was done to assess the effectiveness of retrofitting culverts with baffles to improve fish passage. The long term results showed that...

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 John Wiley & Sons Ltd.

Titre distribution patterns of infectious haematopoietic necrosis virus in ovarian fluids of hatchery and feral salmon populations

USGS Publications Warehouse

Mulcahy, D.; Pascho, R.J.; Jenes, C.K.

1983-01-01

Infectious haematopoietic mecrosis virus (IHNV) is enzootic in virtually all populations of sockeye salmon, Oncorhynchus nerka (Walbaum), and in populations of chinook salmon, O. tshawytscha (Walbaum), of the Sacramento River drainage in California. This disease is an obstacle in hatcheries using brood stocks from these populations. However, naturally spawning sockeye salmon are highly successful and are the most important commercially fished salmon species in the United States. Most of the commercial landings of sockeye salmon are of feral fish originating in Alaska. The success of natural populations of salmon in which IHNV is enzootic, and the recurrent outbreaks of the disease in hatchery fish, led us to compare IHNW prevalence rates in hatchery and feral salmon populations.

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).

40 CFR 35.1640-1 - Application review criteria.

Code of Federal Regulations, 2011 CFR

2011-07-01

... improvement in fish and wildlife habitat and associated beneficial effects on specific fish populations of... economic structure of the population residing near the lake which would use the improved lake for... freshwater lakes within 80 kilometer radius already adequately serve the population; and (v) Whether the...

40 CFR 35.1640-1 - Application review criteria.

Code of Federal Regulations, 2012 CFR

2012-07-01

... improvement in fish and wildlife habitat and associated beneficial effects on specific fish populations of... economic structure of the population residing near the lake which would use the improved lake for... freshwater lakes within 80 kilometer radius already adequately serve the population; and (v) Whether the...

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...

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.

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.

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...

Environmental Factors Affecting Large-Bodied Coral Reef Fish Assemblages in the Mariana Archipelago

PubMed Central

Richards, Benjamin L.; Williams, Ivor D.; Vetter, Oliver J.; Williams, Gareth J.

2012-01-01

Large-bodied reef fishes represent an economically and ecologically important segment of the coral reef fish assemblage. Many of these individuals supply the bulk of the reproductive output for their population and have a disproportionate effect on their environment (e.g. as apex predators or bioeroding herbivores). Large-bodied reef fishes also tend to be at greatest risk of overfishing, and their loss can result in a myriad of either cascading (direct) or indirect trophic and other effects. While many studies have investigated habitat characteristics affecting populations of small-bodied reef fishes, few have explored the relationship between large-bodied species and their environment. Here, we describe the distribution of the large-bodied reef fishes in the Mariana Archipelago with an emphasis on the environmental factors associated with their distribution. Of the factors considered in this study, a negative association with human population density showed the highest relative influence on the distribution of large-bodied reef fishes; however, depth, water temperature, and distance to deep water also were important. These findings provide new information on the ecology of large-bodied reef fishes can inform discussions concerning essential fish habitat and ecosystem-based management for these species and highlight important knowledge gaps worthy of additional research. PMID:22384014

Environmental factors affecting large-bodied coral reef fish assemblages in the Mariana Archipelago.

PubMed

Richards, Benjamin L; Williams, Ivor D; Vetter, Oliver J; Williams, Gareth J

2012-01-01

Large-bodied reef fishes represent an economically and ecologically important segment of the coral reef fish assemblage. Many of these individuals supply the bulk of the reproductive output for their population and have a disproportionate effect on their environment (e.g. as apex predators or bioeroding herbivores). Large-bodied reef fishes also tend to be at greatest risk of overfishing, and their loss can result in a myriad of either cascading (direct) or indirect trophic and other effects. While many studies have investigated habitat characteristics affecting populations of small-bodied reef fishes, few have explored the relationship between large-bodied species and their environment. Here, we describe the distribution of the large-bodied reef fishes in the Mariana Archipelago with an emphasis on the environmental factors associated with their distribution. Of the factors considered in this study, a negative association with human population density showed the highest relative influence on the distribution of large-bodied reef fishes; however, depth, water temperature, and distance to deep water also were important. These findings provide new information on the ecology of large-bodied reef fishes can inform discussions concerning essential fish habitat and ecosystem-based management for these species and highlight important knowledge gaps worthy of additional research.

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.

Sequential tests for infectious hematopoietic necrosis virus in individuals and populations of sockeye salmon

USGS Publications Warehouse

Mulcahy, Daniel M.; Pascho, Ron

1986-01-01

The incidence and titer distribution of infectious hematopoietic necrosis virus in cavity fluid from spent female sockeye salmon (Oncorhynchus nerka) varied little when fish from a naturally spawning population were sampled three times on alternate days. However, when prespawning female sockeye salmon from a second population were individually tagged, penned, and sampled daily, the incidence and proportion of fish with high virus titer rose over a 6-d period. In 10 instances, consecutive cavity fluid samples from the same fish reverted from virus-positive to virus-negative. We suggest that spent fish should be sampled when accurate and quantitative data on the incidence and level of the virus are required.

Microbial community structures in foaming and nonfoaming full-scale wastewater treatment plants.

PubMed

de los Reyes, Francis L; Rothauszky, Dagmar; Raskin, Lutgarde

2002-01-01

A survey of full-scale activated-sludge plants in Illinois revealed that filamentous foaming is a widespread problem in the state, and that the causes and consequences of foaming control strategies are not fully understood. To link microbial community structure to foam occurrence, microbial populations in eight foaming and nine nonfoaming full-scale activated-sludge systems were quantified using oligonucleotide hybridization probes targeting the ribosomal RNA (rRNA) of the mycolata; Gordonia spp.; Gordonia amarae; "Candidatus Microthrix parvicella"; the alpha-, beta-, and gamma-subclasses of the Proteobacteria, and members of the Cytophaga-Flavobacteria. Parallel measurements of microbial population abundance using hybridization of extracted RNA and fluorescence in situ hybridization (FISH) showed that the levels of mycolata, particularly Gordonia spp., were higher in most foaming systems compared with nonfoaming systems. Fluorescence in situ hybridization and microscopy suggested the involvement of "Candidatus Microthrix parvicella" and Skermania piniformis in foam formation in other plants. Finally, high numbers of "Candidatus Microthrix parvicella" were detected by FISH in foam and mixed liquor samples of one plant, whereas the corresponding levels of rRNA were low. This finding implies that inactive "Candidatus Microthrix parvicella" cells (i.e., cells with low rRNA levels) can cause foaming.

Three sympatric karyomorphs in the fish Astyanax fasciatus (Teleostei, Characidae) do not seem to hybridize in natural populations

PubMed Central

Ferreira-Neto, Maressa; Artoni, Roberto Ferreira; Vicari, Marcelo Ricardo; Moreira-Filho, Orlando; Camacho, Juan Pedro Martínez; Bakkali, Mohammed; de Oliveira, Claudio; Foresti, Fausto

2012-01-01

Abstract Ninety individuals of the characid fish Astyanax fasciatus (Cuvier, 1819) were collected at Água da Madalena stream (Botucatu, São Paulo, Brazil) and analyzed for diploid chromosome number 2n and karyotype composition as well as for the chromosomal location of the 5S and 18S ribosomal DNA (rDNA). Whereas no chromosome differences were associated with sex, three different karyomorphs with diploid chromosome numbers 2n=46, 2n=48 and 2n=50 were found. No intermediate 2n numbers were discovered. The 2n=50 karyomorph showed some differences in 18S rDNA location compared to the two other karyomorphs. Finally, all specimens with the 2n=46 karyomorph showed the presence of a partly heterochromatic macro supernumerary chromosome, which was absent in all individuals with the two other karyomorphs. All these results suggest that indviduals of the three different karyomorphs are not likely to hybridize in the examined populations. Our findings strongly suggest the presence of three separate species (sensu biological species concept) easily diagnosed on the basis of differences in the diploid chromosome numbers and other chromosomal markers. PMID:24260650

Assessing the feasibility of native fish reintroductions: a framework applied to threatened bull trout

USGS Publications Warehouse

Dunham, Jason B.; Gallo, Kirsten; Shively, Dan; Allen, Chris; Goehring, Brad

2011-01-01

Translocations to recover native fishes have resulted in mixed success. One reason for the failure of these actions is inadequate assessments of their feasibility prior to implementation. Here, we provide a framework developed to assess the feasibility of one type of translocation-reintroduction. The framework was founded on two simple components of feasibility: the potential for recipient habitats to support a reintroduction and the potential of available donor populations to support a reintroduction. Within each component, we developed a series of key questions. The final assessment was based on a scoring system that incorporated consideration of uncertainty in available information. The result was a simple yet transparent system for assessing reintroduction feasibility that can be rapidly applied in practice. We applied this assessment framework to the potential reintroduction of threatened bull trout Salvelinus confluentus into the Clackamas River, Oregon. In this case, the assessment suggested that the degree of feasibility for reintroduction was high based on the potential of recipient habitats and available donor populations. The assessment did not provide a comprehensive treatment of all possible factors that would drive an actual decision to implement a reintroduction,

A predictive model to inform adaptive management of double-crested cormorants and fisheries in Michigan

USGS Publications Warehouse

Tsehaye, Iyob; Jones, Michael L.; Irwin, Brian J.; Fielder, David G.; Breck, James E.; Luukkonen, David R.

2015-01-01

The proliferation of double-crested cormorants (DCCOs; Phalacrocorax auritus) in North America has raised concerns over their potential negative impacts on game, cultured and forage fishes, island and terrestrial resources, and other colonial water birds, leading to increased public demands to reduce their abundance. By combining fish surplus production and bird functional feeding response models, we developed a deterministic predictive model representing bird–fish interactions to inform an adaptive management process for the control of DCCOs in multiple colonies in Michigan. Comparisons of model predictions with observations of changes in DCCO numbers under management measures implemented from 2004 to 2012 suggested that our relatively simple model was able to accurately reconstruct past DCCO population dynamics. These comparisons helped discriminate among alternative parameterizations of demographic processes that were poorly known, especially site fidelity. Using sensitivity analysis, we also identified remaining critical uncertainties (mainly in the spatial distributions of fish vs. DCCO feeding areas) that can be used to prioritize future research and monitoring needs. Model forecasts suggested that continuation of existing control efforts would be sufficient to achieve long-term DCCO control targets in Michigan and that DCCO control may be necessary to achieve management goals for some DCCO-impacted fisheries in the state. Finally, our model can be extended by accounting for parametric or ecological uncertainty and including more complex assumptions on DCCO–fish interactions as part of the adaptive management process.

Efficiently estimating salmon escapement uncertainty using systematically sampled data

USGS Publications Warehouse

Reynolds, Joel H.; Woody, Carol Ann; Gove, Nancy E.; Fair, Lowell F.

2007-01-01

Fish escapement is generally monitored using nonreplicated systematic sampling designs (e.g., via visual counts from towers or hydroacoustic counts). These sampling designs support a variety of methods for estimating the variance of the total escapement. Unfortunately, all the methods give biased results, with the magnitude of the bias being determined by the underlying process patterns. Fish escapement commonly exhibits positive autocorrelation and nonlinear patterns, such as diurnal and seasonal patterns. For these patterns, poor choice of variance estimator can needlessly increase the uncertainty managers have to deal with in sustaining fish populations. We illustrate the effect of sampling design and variance estimator choice on variance estimates of total escapement for anadromous salmonids from systematic samples of fish passage. Using simulated tower counts of sockeye salmon Oncorhynchus nerka escapement on the Kvichak River, Alaska, five variance estimators for nonreplicated systematic samples were compared to determine the least biased. Using the least biased variance estimator, four confidence interval estimators were compared for expected coverage and mean interval width. Finally, five systematic sampling designs were compared to determine the design giving the smallest average variance estimate for total annual escapement. For nonreplicated systematic samples of fish escapement, all variance estimators were positively biased. Compared to the other estimators, the least biased estimator reduced bias by, on average, from 12% to 98%. All confidence intervals gave effectively identical results. Replicated systematic sampling designs consistently provided the smallest average estimated variance among those compared.

Development of a probabilistic PCB-bioaccumulation model for six fish species in the Hudson River

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

Stackelberg, K. von; Menzie, C.

1995-12-31

In 1984 the US Environmental Protection Agency (USEPA) completed a Feasibility Study on the Hudson River that investigated remedial alternatives and issued a Record of Decision (ROD) later that year. In December 1989 USEPA decided to reassess the No Action decision for Hudson River sediments. This reassessment consists of three phases: Interim Characterization and Evaluation (Phase 1); Further Site Characterization and Analysis (Phase 2); and, Feasibility study (Phase 3). A Phase 1 report was completed in August, 1991. The team then completed a Final Work Plan for Phase 2 in September 1992. This work plan identified various PCB fate andmore » transport modeling activities to support the Hudson River PCB Reassessment Remedial Investigation and Feasibility Study (RI/FS). This talk provides a description of the development of a Probabilistic bioaccumulation models to describe the uptake of PCBs on a congener-specific basis in six fish species. The authors have developed a framework for relating body burdens of PCBs in fish to exposure concentrations in Hudson River water and sediments. This framework is used to understand historical and current relationships as well as to predict fish body burdens for future conditions under specific remediation and no action scenarios. The framework incorporates a probabilistic approach to predict distributions in PCB body burdens for selected fish species. These models can predict single population statistics such as the average expected values of PCBs under specific scenarios as well as the distribution of expected concentrations.« less

Trends in the exploitation of South Atlantic shark populations.

PubMed

Barreto, Rodrigo; Ferretti, Francesco; Flemming, Joanna M; Amorim, Alberto; Andrade, Humber; Worm, Boris; Lessa, Rosangela

2016-08-01

Approximately 25% of globally reported shark catches occur in Atlantic pelagic longline fisheries. Strong declines in shark populations have been detected in the North Atlantic, whereas in the South Atlantic the situation is less clear, although fishing effort has been increasing in this region since the late 1970s. We synthesized information on shark catch rates (based on 871,177 sharks caught on 86,492 longline sets) for the major species caught by multiple fleets in the South Atlantic between 1979 and 2011. We complied records from fishing logbooks of fishing companies, fishers, and onboard observers that were supplied to Brazilian institutions. By using exploratory data analysis and literature sources, we identified 3 phases of exploitation in these data (Supporting Information). From 1979 to 1997 (phase A), 5 fleets (40 vessels) fished mainly for tunas. From 1998 to 2008 (phase B), 20 fleets (100 vessels) fished for tunas, swordfishes, and sharks. From 2008 to 2011 (phase C), 3 fleets (30 vessels) fished for multiple species, but restrictive measures were implemented. We used generalized linear models to standardize catch rates and identify trends in each of these phases. Shark catch rates increased from 1979 to 1997, when fishing effort was low, decreased from 1998 to 2008, when fishing effort increased substantially, and remained stable or increased from 2008 to 2011, when fishing effort was again low. Our results indicate that most shark populations affected by longlines in the South Atlantic are currently depleted, but these populations may recover if fishing effort is reduced accordingly. In this context, it is problematic that comprehensive data collection, monitoring, and management of these fisheries ceased after 2012. Concurrently with the fact that Brazil is newly identified by FAO among the largest (and in fastest expansion) shark sub-products consumer market worldwide. © 2015 Society for Conservation Biology.

Modeling the effects of land use and climate change on riverine smallmouth bass

USGS Publications Warehouse

Peterson, J.T.; Kwak, T.J.

1999-01-01

Anthropogenic changes in temperature and stream flow, associated with watershed land use and climate change, are critical influences on the distribution and abundance of riverine fishes. To project the effects of changing land use and climate, we modeled a smallmouth bass (Micropterus dolomieu) population in a midwestern USA, large river- floodplain ecosystem under historical (1915-1925), present (1977-1990), and future (2060, influenced by climate change) temperature and flow regimes. The age-structured model included parameters for temperature and river discharge during critical seasonal periods, fish population dynamics, and fishing harvest. Model relationships were developed from empirical field data collected over a 13-yr period. Sensitivity analyses indicated that discharge during the spawning/rearing period had a greater effect on adult density and fishing yield than did spawning/rearing temperature or winter discharge. Simulations for 100 years projected a 139% greater mean fish density under a historical flow regime (64.9 fish/ha) than that estimated for the present (27.1 fish/ha) with a sustainable fishing harvest under both flow regimes. Simulations under future climate-change-induced temperature and flow regimes with present land use projected a 69% decrease in mean fish density (8.5 fish/ha) from present and an unstable population that went extinct during 56% of the simulations. However, when simulated under a future climate-altered temperature and flow regime with historical land use, the population increased by 66% (45.0 fish/ha) from present and sustained a harvest. Our findings suggest that land-use changes may be a greater detriment to riverine fishes than projected climate change and that the combined effects of both factors may lead to local species extinction. However, the negative effects of increased temperature and precipitation associated with future global warming could be mitigated by river channel, floodplain, and watershed restoration.

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.

An ecological model of the habitat mosaic in estuarine nursery areas: Part II – Projecting effects of sea level rise on fish production

EPA Science Inventory

Understanding the response of fish populations to habitat change mediated by sea level rise (SLR) is a key component of ecosystem-based management. Yet, no direct link has been established between habitat change due to SLR and fish population production. Here we take a coupled ...

Large-Scale Paraphrasing for Natural Language Understanding

DTIC Science & Technology

2018-04-01

to manufacture , use, or sell any patented invention that may relate to them. This report is the result of contracted fundamental research deemed...station contaminated local fish populations Atomic power generation in Springfield polluted indigenous seafood stocks Radioactive power generation...from PPDB. Springfield’s nuclear power plant contaminated local fish populations nuclear power station nuclear plant power plant fish stocks

Modeling fish community dynamics in Florida Everglades: Role of temperature variation

USGS Publications Warehouse

Al-Rabai'ah, H. A.; Koh, H. L.; DeAngelis, Donald L.; Lee, Hooi-Ling

2002-01-01

The model shows that the temperature dependent starvation mortality is an important factor that influences fish population densities. It also shows high fish population densities at some temperature ranges when this consumption need is minimum. Several sensitivity analyses involving variations in temperature terms, food resources and water levels are conducted to ascertain the relative importance of temperature dependence terms.

Dietary intake and development of a quantitative food-frequency questionnaire for the Barbados National Cancer Study.

PubMed

Sharma, Sangita; Cao, Xia; Harris, Rachel; Hennis, Anselm J M; Leske, M Cristina; Wu, Suh-Yuh

2007-05-01

To develop a quantitative food-frequency questionnaire (QFFQ) for the Barbados National Cancer Study (BNCS) that will permit examination of associations of diet with breast and prostate cancer. Population intake data from the year 2000 Barbados Food Consumption and Anthropometric Surveys (BFCAS 2000) were used to derive a list of foods consumed by the population. A 192-item draft QFFQ was developed from this list. Barbados, West Indies provides an ideal environment to understand cancer risk in African-origin populations, with high relevance to African-Americans. The BNCS is a population-based case-control study examining risk factors for breast and prostate cancer in such populations. A total of 1600 persons, 18 years and older, completed a 24-hour recall in the BFCAS 2000. Fifty of 63 randomly selected residents (79% response rate) gave additional updated information on foods consumed. The 50 participants provided a one-time 24-hour recall and completed the draft QFFQ. The final instrument contains 148 items: breads, cakes, cereals = 17; rice, pastas, noodles = 8; dairy = 10; meat, fish, poultry = 42; fruit = 16; vegetables = 26; soft drinks = 14; alcoholic beverages = 5; others = 10. Additional questions include supplement use and food preparation methods such as grilling. The final instrument is concise, complete and the most up-to-date for assessing the food and nutrient intake of African-origin Barbadians and the associations with breast and prostate cancer.

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.

40 CFR 125.70 - Purpose and scope.

Code of Federal Regulations, 2010 CFR

2010-07-01

... propagation of a balanced, indigenous population of shellfish, fish and wildlife in and on the body of water... assure the protection and propagation of a balanced indigenous population of shellfish, fish and wildlife...

40 CFR 125.70 - Purpose and scope.

Code of Federal Regulations, 2012 CFR

2012-07-01

... propagation of a balanced, indigenous population of shellfish, fish and wildlife in and on the body of water... assure the protection and propagation of a balanced indigenous population of shellfish, fish and wildlife...

40 CFR 125.70 - Purpose and scope.

Code of Federal Regulations, 2011 CFR

2011-07-01

... propagation of a balanced, indigenous population of shellfish, fish and wildlife in and on the body of water... assure the protection and propagation of a balanced indigenous population of shellfish, fish and wildlife...

40 CFR 125.70 - Purpose and scope.

Code of Federal Regulations, 2013 CFR

2013-07-01

... propagation of a balanced, indigenous population of shellfish, fish and wildlife in and on the body of water... assure the protection and propagation of a balanced indigenous population of shellfish, fish and wildlife...

40 CFR 125.70 - Purpose and scope.

Code of Federal Regulations, 2014 CFR

2014-07-01

... propagation of a balanced, indigenous population of shellfish, fish and wildlife in and on the body of water... assure the protection and propagation of a balanced indigenous population of shellfish, fish and wildlife...

Spatial and temporal variation at major histocompatibility complex class IIB genes in the endangered Blakiston's fish owl.

PubMed

Kohyama, Tetsuo I; Omote, Keita; Nishida, Chizuko; Takenaka, Takeshi; Saito, Keisuke; Fujimoto, Satoshi; Masuda, Ryuichi

2015-01-01

Quantifying intraspecific genetic variation in functionally important genes, such as those of the major histocompatibility complex (MHC), is important in the establishment of conservation plans for endangered species. The MHC genes play a crucial role in the vertebrate immune system and generally show high levels of diversity, which is likely due to pathogen-driven balancing selection. The endangered Blakiston's fish owl (Bubo blakistoni) has suffered marked population declines on Hokkaido Island, Japan, during the past several decades due to human-induced habitat loss and fragmentation. We investigated the spatial and temporal patterns of genetic diversity in MHC class IIβ genes in Blakiston's fish owl, using massively parallel pyrosequencing. We found that the Blakiston's fish owl genome contains at least eight MHC class IIβ loci, indicating recent gene duplications. An analysis of sequence polymorphism provided evidence that balancing selection acted in the past. The level of MHC variation, however, was low in the current fish owl populations in Hokkaido: only 19 alleles were identified from 174 individuals. We detected considerable spatial differences in MHC diversity among the geographically isolated populations. We also detected a decline of MHC diversity in some local populations during the past decades. Our study demonstrated that the current spatial patterns of MHC variation in Blakiston's fish owl populations have been shaped by loss of variation due to the decline and fragmentation of populations, and that the short-term effects of genetic drift have counteracted the long-term effects of balancing selection.

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...

Methods for assessing fish populations

Treesearch

Kevin L. Pope; Steve E. Lochmann; Michael K. Young

2010-01-01

Fisheries managers are likely to assess fish populations at some point during the fisheries management process. Managers that follow the fisheries management process (see Chapter 5) might find their knowledge base insufficient during the steps of problem identification or management action and must assess a population before appropriate actions can be taken. Managers...

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.

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.

Supportive breeding boosts natural population abundance with minimal negative impacts on fitness of a wild population of Chinook salmon

PubMed Central

Hess, Maureen A; Rabe, Craig D; Vogel, Jason L; Stephenson, Jeff J; Nelson, Doug D; Narum, Shawn R

2012-01-01

While supportive breeding programmes strive to minimize negative genetic impacts to populations, case studies have found evidence for reduced fitness of artificially produced individuals when they reproduce in the wild. Pedigrees of two complete generations were tracked with molecular markers to investigate differences in reproductive success (RS) of wild and hatchery-reared Chinook salmon spawning in the natural environment to address questions regarding the demographic and genetic impacts of supplementation to a natural population. Results show a demographic boost to the population from supplementation. On average, fish taken into the hatchery produced 4.7 times more adult offspring, and 1.3 times more adult grand-offspring than naturally reproducing fish. Of the wild and hatchery fish that successfully reproduced, we found no significant differences in RS between any comparisons, but hatchery-reared males typically had lower RS values than wild males. Mean relative reproductive success (RRS) for hatchery F1 females and males was 1.11 (P = 0.84) and 0.89 (P = 0.56), respectively. RRS of hatchery-reared fish (H) that mated in the wild with either hatchery or wild-origin (W) fish was generally equivalent to W × W matings. Mean RRS of H × W and H × H matings was 1.07 (P = 0.92) and 0.94 (P = 0.95), respectively. We conclude that fish chosen for hatchery rearing did not have a detectable negative impact on the fitness of wild fish by mating with them for a single generation. Results suggest that supplementation following similar management practices (e.g. 100% local, wild-origin brood stock) can successfully boost population size with minimal impacts on the fitness of salmon in the wild. PMID:23025818

Population dynamics and potential of fisheries stock enhancement: practical theory for assessment and policy analysis.

PubMed

Lorenzen, Kai

2005-01-29

The population dynamics of fisheries stock enhancement, and its potential for generating benefits over and above those obtainable from optimal exploitation of wild stocks alone are poorly understood and highly controversial. I review pertinent knowledge of fish population biology, and extend the dynamic pool theory of fishing to stock enhancement by unpacking recruitment, incorporating regulation in the recruited stock, and accounting for biological differences between wild and hatchery fish. I then analyse the dynamics of stock enhancement and its potential role in fisheries management, using the candidate stock of North Sea sole as an example and considering economic as well as biological criteria. Enhancement through release of recruits or advanced juveniles is predicted to increase total yield and stock abundance, but reduce abundance of the naturally recruited stock component through compensatory responses or overfishing. Economic feasibility of enhancement is subject to strong constraints, including trade-offs between the costs of fishing and hatchery releases. Costs of hatchery fish strongly influence optimal policy, which may range from no enhancement at high cost to high levels of stocking and fishing effort at low cost. Release of genetically maladapted fish reduces the effectiveness of enhancement, and is most detrimental overall if fitness of hatchery fish is only moderately compromised. As a temporary measure for the rebuilding of depleted stocks, enhancement cannot substitute for effort limitation, and is advantageous as an auxiliary measure only if the population has been reduced to a very low proportion of its unexploited biomass. Quantitative analysis of population dynamics is central to the responsible use of stock enhancement in fisheries management, and the necessary tools are available.

Indicators of AEI applied to the Delaware Estuary.

PubMed

Barnthouse, Lawrence W; Heimbuch, Douglas G; Anthony, Vaughn C; Hilborn, Ray W; Myers, Ransom A

2002-05-18

We evaluated the impacts of entrainment and impingement at the Salem Generating Station on fish populations and communities in the Delaware Estuary. In the absence of an agreed-upon regulatory definition of "adverse environmental impact" (AEI), we developed three independent benchmarks of AEI based on observed or predicted changes that could threaten the sustainability of a population or the integrity of a community. Our benchmarks of AEI included: (1) disruption of the balanced indigenous community of fish in the vicinity of Salem (the "BIC" analysis); (2) a continued downward trend in the abundance of one or more susceptible fish species (the "Trends" analysis); and (3) occurrence of entrainment/impingement mortality sufficient, in combination with fishing mortality, to jeopardize the future sustainability of one or more populations (the "Stock Jeopardy" analysis). The BIC analysis utilized nearly 30 years of species presence/absence data collected in the immediate vicinity of Salem. The Trends analysis examined three independent data sets that document trends in the abundance of juvenile fish throughout the estuary over the past 20 years. The Stock Jeopardy analysis used two different assessment models to quantify potential long-term impacts of entrainment and impingement on susceptible fish populations. For one of these models, the compensatory capacities of the modeled species were quantified through meta-analysis of spawner-recruit data available for several hundred fish stocks. All three analyses indicated that the fish populations and communities of the Delaware Estuary are healthy and show no evidence of an adverse impact due to Salem. Although the specific models and analyses used at Salem are not applicable to every facility, we believe that a weight of evidence approach that evaluates multiple benchmarks of AEI using both retrospective and predictive methods is the best approach for assessing entrainment and impingement impacts at existing facilities.

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

Long-term changes in the fish assemblage of a neotropical hydroelectric reservoir.

PubMed

Orsi, M L; Britton, J R

2014-06-01

The changes in the fish assemblage of the Capivara Reservoir, Brazil, were assessed over a 20 year period. Of 50 native fishes present in the initial samples, 27 were no longer present in the final samples, but there had been an addition of 11 invasive fishes, suggesting the occurrence of substantial shifts in fish diversity and abundance. © 2014 The Fisheries Society of the British Isles.

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.

Status and trends in the fish community of Lake Superior, 2012

USGS Publications Warehouse

Gorman, Owen T.; Evrard, Lori M.; Cholwek, Gary A.; Vinson, Mark

2012-01-01

Due to ship mechanical failures, nearshore sampling was delayed from mid-May to mid-June to mid-June to late August. The shift to summer sampling when the lake was stratified may have affected our estimates, thus our estimates of status and trends for the nearshore fish community in 2012 are tentative, pending results of future surveys. However, the results of the 2012 survey are comparable with those during 2009 and 2010 when lake-wide fish biomass declined to < 1.40 kg/ha. Declines in prey fish biomass since the late 1990s can be attributed to a combination of increased predation by recovered lake trout populations and infrequent and weak recruitment by the principal prey fishes, cisco and bloater. In turn declines in lake trout biomass since the mid-2000s are likely linked to declines in prey fish biomass. If lean and siscowet lake trout populations in nearshore waters continue to remain at current levels, predation mortality will likely maintain the relatively low prey fish biomass observed in recent years. Alternatively, if lake trout populations show a substantial decline in abundance in upcoming years, prey fish populations may rebound in a fashion reminiscent to what occurred in the late 1970s to mid-1980s. However, this scenario depends on substantial increases in harvest of lake trout, which seems unlikely given that levels of lake trout harvest have been flat or declining in many regions of Lake Superior since 2000.

Molecular markers for genetic diversity, gene flow and genetic population structure of freshwater mussel species.

PubMed

Choupina, A B; Martins, I M

2014-08-01

Freshwater mussel species are in global decline. Anthropogenic changes of river channels and the decrease of autochthonous fish population, the natural hosts of mussels larval stages (glochidia), are the main causes. Therefore, the conservation of mussel species depends not only on habitat conservation, but also on the availability of the fish host. In Portugal, information concerning most of the mussel species is remarkably scarce. One of the most known species, Unio pictorum is also in decline however, in the basins of the rivers Tua and Sabor (Northeast of Portugal), there is some indication of relatively large populations. The aforementioned rivers can be extremely important for this species conservation not only in Portugal, but also in the remaining Iberian Peninsula. Thus, it is important to obtain data concerning Unio pictorum bioecology (distribution, habitat requirements, population structure, genetic variability, reproductive cycle and recruitment rates), as well as the genetic variability and structure of the population. Concomitantly, information concerning fish population structure, the importance of the different fish species as "glochidia" hosts and their appropriate density to allow effective mussel recruitment, will also be assessed. The achieved data is crucial to obtain information to develop effective management measures in order to promote the conservation of this bivalve species, the conservation of autochthonous fish populations, and consequently the integrity of the river habitats.

The cumulative MeHg and PCBs exposure and risk of tribal ...

EPA Pesticide Factsheets

Studies have shown that the U.S. population continues to be exposed to methyl mercury (MeHg) and polychlorinated biphenyls (PCBs) due to the long half-life of those environmental contaminants. Fish intake of Tribal populations is much higher than the U.S. general population due to dietary habits and unique cultural practices. Large fish tissue concentration data sets from the Environmental Protections Agency’s (EPA’s) Office of Water, USGS’s EMMMA program, and other data sources, were integrated, analyzed, and combined with recent tribal fish intake data for exposure analyses using the dietary module within EPA’s SHEDS-Multimedia model. SHEDS-Multimedia is a physically-based, probabilistic model, which can simulate cumulative (multiple chemicals) or aggregate (single chemical) exposures over time for a population via various pathways of exposure for a variety of multimedia, multipathway environmental chemicals. Our results show that MeHg and total PCBs exposure of tribal populations from fish are about 3 to 10 and 5 to 15 times higher than the US general population, respectively, and that the estimated exposures pose potential health risks. The cumulative exposures of MeHg and total PCBs will be assessed to generate the joint exposure profiles for Tribal and US general populations. Model sensitivity analyses will identify the important contributions of the cumulative exposures of MeHg and total PCBs such as fish types, locations, and size, and key expos

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 these birds or with a conclusion that certain contaminants do not need additional control.

Variations in egg characteristics of ruffe Gymnocephalus cernua inhabiting brackish and freshwater environments

NASA Astrophysics Data System (ADS)

Svirgsden, Roland; Albert, Anu; Rohtla, Mehis; Taal, Imre; Saks, Lauri; Verliin, Aare; Kesler, Martin; Hubel, Kalvi; Vetemaa, Markus; Saat, Toomas

2015-09-01

Egg characteristics of teleost fishes are affected by various abiotic and biotic factors. In order to reproduce successfully, freshwater fishes inhabiting brackish environments must alter their reproductive characteristics, including egg properties, to increased osmotic pressure. Ruffe Gymnocephalus cernua was used as a model species to compare egg characteristics between fish populations inhabiting brackish and freshwater environments. Fish from the brackish environment had larger eggs with higher energy content than the individuals originating from freshwater. In freshwater, eggs from the first batch were larger than from the second. Female size correlated positively with egg size in the brackish water population. In freshwater, this correlation was evident only with eggs from the first batch. Only a weak positive correlation was found between fish condition and egg size in females from the brackish water population. Egg size variation did not differ between sites, nor was it correlated with mean egg size or any other maternal traits within populations. These results indicate significant modifications in reproductive strategies between brackish and freshwater ruffe populations. Additionally, results show that at least in freshwater, the first batch of eggs is of the highest quality and therefore more important for reproduction.

So long to genetic diversity, and thanks for all the fish.

PubMed

Allendorf, Fred W; Berry, Oliver; Ryman, Nils

2014-01-01

The world faces a global fishing crisis. Wild marine fisheries comprise nearly 15% of all animal protein in the human diet, but, according to the U.N. Food and Agriculture Organization, nearly 60% of all commercially important marine fish stocks are overexploited, recovering, or depleted (FAO 2012; Fig. 1). Some authors have suggested that the large population sizes of harvested marine fish make even collapsed populations resistant to the loss of genetic variation by genetic drift (e.g. Beverton 1990). In contrast, others have argued that the loss of alleles because of overfishing may actually be more dramatic in large populations than in small ones (Ryman et al. 1995). In this issue, Pinsky & Palumbi (2014) report that overfished populations have approximately 2% lower heterozygosity and 12% lower allelic richness than populations that are not overfished. They also performed simulations which suggest that their estimates likely underestimate the actual loss of rare alleles by a factor of three or four. This important paper shows that the harvesting of marine fish can have genetic effects that threaten the long-term sustainability of this valuable resource. © 2013 John Wiley & Sons Ltd.

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.

Effect of vitamin C on innate immune responses of rainbow trout (Oncorhynchus mykiss) leukocytes.

PubMed

Leal, Esther; Zarza, Carlos; Tafalla, Carolina

2017-08-01

Vitamin C, also known as ascorbic acid, is an essential micronutrient that influences a wide variety of physiological processes, including immunological functions. Although the positive effects of vitamin C supplementation on the immunological status of fish has been established in different species, the bases for these positive effects are still unknown. Hence, the aim of our study was to evaluate the in vitro effect of vitamin C on several innate immune functions of rainbow trout (Oncorhynchus mykiss) leukocyte populations. For this, we assessed the effects exerted on the established rainbow trout monocyte-macrophage cell line RTS11, and compared them to those observed in trout head kidney leukocytes. Our results demonstrate that vitamin C increases the production of reactive oxygen species and the percentage of phagocytic cells in both cell populations. On the other hand, vitamin C had no effect on the surface MHC II levels and only in the case of RTS11 cells increased the capacity of these cells to migrate towards the CK9 chemokine. Finally, vitamin C also increased the transcription of several pro-inflammatory and antimicrobial genes elicited by Escherichia coli, with some differences depending on the cell population studied. Our results contribute to further understand how vitamin C supplementation regulates the fish immune system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multiple zebrafish atoh1 genes specify a diversity of neuronal types in the zebrafish cerebellum.

PubMed

Kidwell, Chelsea U; Su, Chen-Ying; Hibi, Masahiko; Moens, Cecilia B

2018-06-01

A single Atoh1 basic-helix-loop-helix transcription factor specifies multiple neuron types in the mammalian cerebellum and anterior hindbrain. The zebrafish genome encodes three paralagous atoh1 genes whose functions in cerebellum and anterior hindbrain development we explore here. With use of a transgenic reporter, we report that zebrafish atoh1c-expressing cells are organized in two distinct domains that are separated both by space and developmental time. An early isthmic expression domain gives rise to an extracerebellar population in rhombomere 1 and an upper rhombic lip domain gives rise to granule cell progenitors that migrate to populate all four granule cell territories of the fish cerebellum. Using genetic mutants we find that of the three zebrafish atoh1 paralogs, atoh1c and atoh1a are required for the full complement of granule neurons. Surprisingly, the two genes are expressed in non-overlapping granule cell progenitor populations, indicating that fish use duplicate atoh1 genes to generate granule cell diversity that is not detected in mammals. Finally, live imaging of granule cell migration in wildtype and atoh1c mutant embryos reveals that while atoh1c is not required for granule cell specification per se, it is required for granule cells to delaminate and migrate away from the rhombic lip. Copyright © 2018 Elsevier Inc. All rights reserved.

78 FR 46820 - Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; Reef Fish Fishery of the Gulf of...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-02

... of Mexico Fishery Management Council (Council). This final rule revises the vermilion snapper... of this rule is to help achieve optimum yield (OY) and prevent overfishing of vermilion and... Through this final rule, NMFS establishes a 10-vermilion snapper recreational bag limit within the 20-fish...

77 FR 1470 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Extension of Time for Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-10

... DEPARTMENT OF COMMERCE International Trade Administration [A-552-801] Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Extension of Time for Final Results of the New Shipper Review AGENCY: Import Administration, International Trade Administration, Department of Commerce. DATES: Effective Date: January 10, 2012. FOR FURTHER...

76 FR 16636 - Pine Island, Matlacha Pass, Island Bay, and Caloosahatchee NWRs, Lee County, FL; Final...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-24

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R4-R-2010-N240; 40136-1265-0000-S3] Pine Island, Matlacha Pass, Island Bay, and Caloosahatchee NWRs, Lee County, FL; Final Comprehensive Conservation Plan and Finding of No Significant Impact for Environmental Assessment AGENCY: Fish and Wildlife...

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

40 CFR 125.57 - Law governing issuance of a section 301(h) modified permit.

Code of Federal Regulations, 2014 CFR

2014-07-01

... propagation of a balanced indigenous population of shellfish, fish, and wildlife, and allows recreational... application do not support a balanced indigenous population of shellfish, fish, and wildlife, or allow...

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…

THE COMPETITION BETWEEN METHYLMERCURY RISKS AND OMEGA-3 POLYUNSATURATED FATTY ACID BENEFITS: A REVIEW OF CONFLICTING EVIDENCE ON FISH CONSUMPTION AND CARDIOVASCULAR HEALTH.

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

LIPFERT, F.W.; SULLIVAN, T.M.

2006-10-31

The health concerns of methylmercury (MeHg) contamination of seafood have recently been extended to include cardiovascular effects, especially premature mortality. Although the fatty acids (fish oils) found in most species are thought to confer a wide range of health benefits, especially to the cardiovascular system, some epidemiological studies have suggested that such benefits may be offset by adverse effects of MeHg. This comprehensive review is based on searches of the NIH MEDLINE database and compares and contrasts 145 published studies involving cardiovascular effects and exposures to mercury and other fish contaminants, intake of fatty acids including dietary supplements of fishmore » oils, and rates of seafood consumption. Since few of these studies include adequate simultaneous measurements of all of these potential predictor variables, we summarized their effects separately, across the available studies of each, and then drew conclusions based on the aggregated findings. It is important to realize that studies of seafood consumption encompass the net effects of all of these predictor variables, but that seafood intake studies are rarely supported by human biomarker measurements that reflect the actual uptake of harmful as well as beneficial fish ingredients. As a result, exposure measurement error is an issue when comparing studies and predictor variables. It is also possible that the observed benefits of eating fish may relate more to the characteristics of the consumers than to those of the fish. We found the evidence for adverse cardiovascular effects of MeHg to be sparse and unconvincing. Studies of cardiovascular mortality show net benefits, and the findings of adverse effects are mainly limited to studies Finland at high mercury exposure levels. By contrast, a very consistent picture of beneficial effects is seen for fatty acids, after recognizing the effects of exposure uncertainties and the presence of threshold effects. Studies based on measured biomarker levels are seen to be the most reliable and present a convincing picture of strong beneficial effects, especially for those causes of death involving cardiac arrhythmia. This conclusion also extends to studies of fish-oil supplementation. Studies based on fish consumption show mainly benefits from increased consumption. This finding is supported by an ecological study at the national population level, for which the lifestyle effects that might be correlated with fish consumption within a given population would be expected to ''average out'' across nations. Finally, the net survival benefits resulting from eating fish are consistent with studies involving complete diets, although benefits are also seen to accrue from reduced consumption of red meat and saturated fats.« less

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.

77 FR 19552 - Endangered and Threatened Species; Range Extension for Endangered Central California Coast Coho...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-02

...We, the National Marine Fisheries Service (NMFS), are issuing a final rule under the Endangered Species Act (ESA) of 1973, as amended, that redefines the geographic range of the endangered Central California Coast (CCC) coho salmon (Oncorhynchus kisutch) Evolutionarily Significant Unit (ESU) to include all naturally spawned populations of coho salmon that occur in Soquel and Aptos creeks. Information supporting this boundary change includes recent observations of coho salmon in Soquel Creek, genetic analysis of these fish indicating they are derived from other nearby populations in the ESU, and the presence of freshwater habitat conditions and watershed processes in Soquel and Aptos Creeks that are similar to those found in closely adjacent watersheds that support coho salmon populations that are part of the ESU. We have also reassessed the status of this ESU throughout its redefined range and conclude that it continues to be endangered.

The West Indian manatee (Trichechus manatus) in Florida: a summary and analysis of biological, ecological, and administrative problems affecting preservation and restoration of the population. Final report

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

Wray, P.

1978-09-01

The population of the West Indian manatee (Trichechus manatus), an endangered species, is estimated at 800-1,000 individuals in peninsular Florida. Observed annual mortality between 1974 and 1977 was 6-8% of the estimated population. Human activities are implicated in much of this mortality. Direct and indirect threats include boat collisions, diver harassment, creation of artificial warm water refuges, vandalism, entanglement in fishing gear, herbicides in food resources, and possible effects of offshore oil exploration. Lack of federal commitment to manatee protection is evidenced by an absence of implementing regulations under the Marine Mammal Protection Act and the Endangered Species Act, absencemore » of a recovery plan for the species, faulty interagency communication, and a lack of law enforcement. Problems are discussed, with recommendations for conservation. (Color illustrations reproduced in black and white)« less

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.

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.

Long-term survival despite low genetic diversity in the critically endangered Madagascar fish-eagle

USGS Publications Warehouse

Johnson, J.A.; Tingay, R.E.; Culver, M.; Hailer, F.; Clarke, M.L.; Mindell, D.P.

2009-01-01

The critically endangered Madagascar fish-eagle (Haliaeetus vociferoides) is considered to be one of the rarest birds of prey globally and at significant risk of extinction. In the most recent census, only 222 adult individuals were recorded with an estimated total breeding population of no more than 100-120 pairs. Here, levels of Madagascar fish-eagle population genetic diversity based on 47 microsatellite loci were compared with its sister species, the African fish-eagle (Haliaeetus vocifer), and 16 of these loci were also characterized in the white-tailed eagle (Haliaeetus albicilla) and the bald eagle (Haliaeetus leucocephalus). Overall, extremely low genetic diversity was observed in the Madagascar fish-eagle compared to other surveyed Haliaeetus species. Determining whether this low diversity is the result of a recent bottleneck or a more historic event has important implications for their conservation. Using a Bayesian coalescent-based method, we show that Madagascar fish-eagles have maintained a small effective population size for hundreds to thousands of years and that its low level of neutral genetic diversity is not the result of a recent bottleneck. Therefore, efforts made to prevent Madagascar fish-eagle extinction should place high priority on maintenance of habitat requirements and reducing direct and indirect human persecution. Given the current rate of deforestation in Madagascar, we further recommend that the population be expanded to occupy a larger geographical distribution. This will help the population persist when exposed to stochastic factors (e.g. climate and disease) that may threaten a species consisting of only 200 adult individuals while inhabiting a rapidly changing landscape. ?? 2008 The Authors.

Demographic changes following mechanical removal of exotic brown trout in an Intermountain West (USA), high-elevation stream

USGS Publications Warehouse

Saunders, W. Carl; Budy, Phaedra E.; Thiede, Gary P.

2015-01-01

Exotic species present a great threat to native fish conservation; however, eradicating exotics is expensive and often impractical. Mechanical removal can be ineffective for eradication, but nonetheless may increase management effectiveness by identifying portions of a watershed that are strong sources of exotics. We used mechanical removal to understand processes driving exotic brown trout (Salmo trutta) populations in the Logan River, Utah. Our goals were to: (i) evaluate the demographic response of brown trout to mechanical removal, (ii) identify sources of brown trout recruitment at a watershed scale and (iii) evaluate whether mechanical removal can reduce brown trout densities. We removed brown trout from 2 km of the Logan River (4174 fish), and 5.6 km of Right Hand Fork (RHF, 15,245 fish), a low-elevation tributary, using single-pass electrofishing. We compared fish abundance and size distributions prior to, and after 2 years of mechanical removal. In the Logan River, immigration to the removal reach and high natural variability in fish abundances limited the response to mechanical removal. In contrast, mechanical removal in RHF resulted in a strong recruitment pulse, shifting the size distribution towards smaller fish. These results suggest that, before removal, density-dependent mortality or emigration of juvenile fish stabilised adult populations and may have provided a source of juveniles to the main stem. Overall, in sites demonstrating strong density-dependent population regulation, or near sources of exotics, short-term mechanical removal has limited effects on brown trout populations but may help identify factors governing populations and inform large-scale management of exotic species.

Long-term survival despite low genetic diversity in the critically endangered Madagascar fish-eagle.

PubMed

Johnson, Jeff A; Tingay, Ruth E; Culver, Melanie; Hailer, Frank; Clarke, Michèle L; Mindell, David P

2009-01-01

The critically endangered Madagascar fish-eagle (Haliaeetus vociferoides) is considered to be one of the rarest birds of prey globally and at significant risk of extinction. In the most recent census, only 222 adult individuals were recorded with an estimated total breeding population of no more than 100-120 pairs. Here, levels of Madagascar fish-eagle population genetic diversity based on 47 microsatellite loci were compared with its sister species, the African fish-eagle (Haliaeetus vocifer), and 16 of these loci were also characterized in the white-tailed eagle (Haliaeetus albicilla) and the bald eagle (Haliaeetus leucocephalus). Overall, extremely low genetic diversity was observed in the Madagascar fish-eagle compared to other surveyed Haliaeetus species. Determining whether this low diversity is the result of a recent bottleneck or a more historic event has important implications for their conservation. Using a Bayesian coalescent-based method, we show that Madagascar fish-eagles have maintained a small effective population size for hundreds to thousands of years and that its low level of neutral genetic diversity is not the result of a recent bottleneck. Therefore, efforts made to prevent Madagascar fish-eagle extinction should place high priority on maintenance of habitat requirements and reducing direct and indirect human persecution. Given the current rate of deforestation in Madagascar, we further recommend that the population be expanded to occupy a larger geographical distribution. This will help the population persist when exposed to stochastic factors (e.g. climate and disease) that may threaten a species consisting of only 200 adult individuals while inhabiting a rapidly changing landscape.

Environmental Impact Statement for the Modernization and Enhancement of Ranges, Airspace, and Training Areas in the Joint Pacific Alaska Range Complex in Alaska. Volume 1 - Executive Summary, Chapters 1 through 10

DTIC Science & Technology

2013-06-01

to short-term behavioral responses and no effects that would be measurable at a population level have been documented. Fish in their native...the sustainable multipurpose use of natural resources (hunting, fishing , trapping, and non- consumptive uses) on military lands, subject to safety...support fish populations year-round, as they freeze in winter or when iced over and lack sufficient dissolved oxygen for fish to survive (USARAK 2004-1

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of a balanced indigenous population of shellfish, fish and wildlife. (3) For the purposes of listing... propagation of a balanced, indigenous population of shellfish, fish and wildlife. Such estimates shall take... water quality criteria for protection and propagation of a balanced, indigenous population of shellfish...

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... of a balanced indigenous population of shellfish, fish and wildlife. (3) For the purposes of listing... propagation of a balanced, indigenous population of shellfish, fish and wildlife. Such estimates shall take... water quality criteria for protection and propagation of a balanced, indigenous population of shellfish...

40 CFR 130.7 - Total maximum daily loads (TMDL) and individual water quality-based effluent limitations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of a balanced indigenous population of shellfish, fish and wildlife. (3) For the purposes of listing... propagation of a balanced, indigenous population of shellfish, fish and wildlife. Such estimates shall take... water quality criteria for protection and propagation of a balanced, indigenous population of shellfish...

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.

Fisheries conservation on the high seas: linking conservation physiology and fisheries ecology for the management of large pelagic fishes

PubMed Central

Horodysky, Andrij Z.; Cooke, Steven J.; Graves, John E.; Brill, Richard W.

2016-01-01

Populations of tunas, billfishes and pelagic sharks are fished at or over capacity in many regions of the world. They are captured by directed commercial and recreational fisheries (the latter of which often promote catch and release) or as incidental catch or bycatch in commercial fisheries. Population assessments of pelagic fishes typically incorporate catch-per-unit-effort time-series data from commercial and recreational fisheries; however, there have been notable changes in target species, areas fished and depth-specific gear deployments over the years that may have affected catchability. Some regional fisheries management organizations take into account the effects of time- and area-specific changes in the behaviours of fish and fishers, as well as fishing gear, to standardize catch-per-unit-effort indices and refine population estimates. However, estimates of changes in stock size over time may be very sensitive to underlying assumptions of the effects of oceanographic conditions and prey distribution on the horizontal and vertical movement patterns and distribution of pelagic fishes. Effective management and successful conservation of pelagic fishes requires a mechanistic understanding of their physiological and behavioural responses to environmental variability, potential for interaction with commercial and recreational fishing gear, and the capture process. The interdisciplinary field of conservation physiology can provide insights into pelagic fish demography and ecology (including environmental relationships and interspecific interactions) by uniting the complementary expertise and skills of fish physiologists and fisheries scientists. The iterative testing by one discipline of hypotheses generated by the other can span the fundamental–applied science continuum, leading to the development of robust insights supporting informed management. The resulting species-specific understanding of physiological abilities and tolerances can help to improve stock assessments, develop effective bycatch-reduction strategies, predict rates of post-release mortality, and forecast the population effects of environmental change. In this synthesis, we review several examples of these interdisciplinary collaborations that currently benefit pelagic fisheries management. PMID:27382467

Impact of minimum catch size on the population viability of Strombus gigas (Mesogastropoda: Strombidae) in Quintana Roo, Mexico.

PubMed

Peel, Joanne R; Mandujano, María del Carmen

2014-12-01

The queen conch Strombus gigas represents one of the most important fishery resources of the Caribbean but heavy fishing pressure has led to the depletion of stocks throughout the region, causing the inclusion of this species into CITES Appendix II and IUCN's Red-List. In Mexico, the queen conch is managed through a minimum fishing size of 200 mm shell length and a fishing quota which usually represents 50% of the adult biomass. The objectives of this study were to determine the intrinsic population growth rate of the queen conch population of Xel-Ha, Quintana Roo, Mexico, and to assess the effects of a regulated fishing impact, simulating the extraction of 50% adult biomass on the population density. We used three different minimum size criteria to demonstrate the effects of minimum catch size on the population density and discuss biological implications. Demographic data was obtained through capture-mark-recapture sampling, collecting all animals encountered during three hours, by three divers, at four different sampling sites of the Xel-Ha inlet. The conch population was sampled each month between 2005 and 2006, and bimonthly between 2006 and 2011, tagging a total of 8,292 animals. Shell length and lip thickness were determined for each individual. The average shell length for conch with formed lip in Xel-Ha was 209.39 ± 14.18 mm and the median 210 mm. Half of the sampled conch with lip ranged between 200 mm and 219 mm shell length. Assuming that the presence of the lip is an indicator for sexual maturity, it can be concluded that many animals may form their lip at greater shell lengths than 200 mm and ought to be considered immature. Estimation of relative adult abundance and densities varied greatly depending on the criteria employed for adult classification. When using a minimum fishing size of 200 mm shell length, between 26.2% and up to 54.8% of the population qualified as adults, which represented a simulated fishing impact of almost one third of the population. When conch extraction was simulated using a classification criteria based on lip thickness, it had a much smaller impact on the population density. We concluded that the best management strategy for S. gigas is a minimum fishing size based on a lip thickness, since it has lower impact on the population density, and given that selective fishing pressure based on size may lead to the appearance of small adult individuals with reduced fecundity. Furthermore, based on the reproductive biology and the results of the simulated fishing, we suggest a minimum lip thickness of ≥ 15 mm, which ensures the protection of reproductive stages, reduces the risk of overfishing, leading to non-viable density reduction.

Detection of a Diverse Marine Fish Fauna Using Environmental DNA from Seawater Samples

PubMed Central

Iversen, Lars Lønsmann; Møller, Peter Rask; Rasmussen, Morten; Willerslev, Eske

2012-01-01

Marine ecosystems worldwide are under threat with many fish species and populations suffering from human over-exploitation. This is greatly impacting global biodiversity, economy and human health. Intriguingly, marine fish are largely surveyed using selective and invasive methods, which are mostly limited to commercial species, and restricted to particular areas with favourable conditions. Furthermore, misidentification of species represents a major problem. Here, we investigate the potential of using metabarcoding of environmental DNA (eDNA) obtained directly from seawater samples to account for marine fish biodiversity. This eDNA approach has recently been used successfully in freshwater environments, but never in marine settings. We isolate eDNA from ½-litre seawater samples collected in a temperate marine ecosystem in Denmark. Using next-generation DNA sequencing of PCR amplicons, we obtain eDNA from 15 different fish species, including both important consumption species, as well as species rarely or never recorded by conventional monitoring. We also detect eDNA from a rare vagrant species in the area; European pilchard (Sardina pilchardus). Additionally, we detect four bird species. Records in national databases confirmed the occurrence of all detected species. To investigate the efficiency of the eDNA approach, we compared its performance with 9 methods conventionally used in marine fish surveys. Promisingly, eDNA covered the fish diversity better than or equal to any of the applied conventional methods. Our study demonstrates that even small samples of seawater contain eDNA from a wide range of local fish species. Finally, in order to examine the potential dispersal of eDNA in oceans, we performed an experiment addressing eDNA degradation in seawater, which shows that even small (100-bp) eDNA fragments degrades beyond detectability within days. Although further studies are needed to validate the eDNA approach in varying environmental conditions, our findings provide a strong proof-of-concept with great perspectives for future monitoring of marine biodiversity and resources. PMID:22952584

Comparative study between quantitative digital image analysis and fluorescence in situ hybridization of breast cancer equivocal human epidermal growth factor receptors 2 score 2(+) cases.

PubMed

Ayad, Essam; Mansy, Mina; Elwi, Dalal; Salem, Mostafa; Salama, Mohamed; Kayser, Klaus

2015-01-01

Optimization of workflow for breast cancer samples with equivocal human epidermal growth factor receptors 2 (HER2)/neu score 2(+) results in routine practice, remains to be a central focus of the on-going efforts to assess HER2 status. According to the College of American Pathologists/American Society of Clinical Oncology guidelines equivocal HER2/neu score 2(+) cases are subject for further testing, usually by fluorescence in situ hybridization (FISH) investigations. It still remains on open question, whether quantitative digital image analysis of HER2 immunohistochemistry (IHC) stained slides can assist in further refining the HER2 score 2(+). To assess utility of quantitative digital analysis of IHC stained slides and compare its performance to FISH in cases of breast cancer with equivocal HER2 score 2(+). Fifteen specimens (previously diagnosed as breast cancer and was evaluated as HER 2(-) score 2(+)) represented the study population. Contemporary new cuts were prepared for re-evaluation of HER2 immunohistochemical studies and FISH examination. All the cases were digitally scanned by iScan (Produced by BioImagene [Now Roche-Ventana]). The IHC signals of HER2 were measured using an automated image analyzing system (MECES, www.Diagnomx.eu/meces). Finally, a comparative study was done between the results of the FISH and the quantitative analysis of the virtual slides. Three out of the 15 cases with equivocal HER2 score 2(+), turned out to be positive (3(+)) by quantitative digital analysis, and 12 were found to be negative in FISH too. Two of these three positive cases proved to be positive with FISH, and only one was negative. Quantitative digital analysis is highly sensitive and relatively specific when compared to FISH in detecting HER2/neu overexpression. Therefore, it represents a potential reliable substitute for FISH in breast cancer cases, which desire further refinement of equivocal IHC results.

Detection of a diverse marine fish fauna using environmental DNA from seawater samples.

PubMed

Thomsen, Philip Francis; Kielgast, Jos; Iversen, Lars Lønsmann; Møller, Peter Rask; Rasmussen, Morten; Willerslev, Eske

2012-01-01

Marine ecosystems worldwide are under threat with many fish species and populations suffering from human over-exploitation. This is greatly impacting global biodiversity, economy and human health. Intriguingly, marine fish are largely surveyed using selective and invasive methods, which are mostly limited to commercial species, and restricted to particular areas with favourable conditions. Furthermore, misidentification of species represents a major problem. Here, we investigate the potential of using metabarcoding of environmental DNA (eDNA) obtained directly from seawater samples to account for marine fish biodiversity. This eDNA approach has recently been used successfully in freshwater environments, but never in marine settings. We isolate eDNA from ½-litre seawater samples collected in a temperate marine ecosystem in Denmark. Using next-generation DNA sequencing of PCR amplicons, we obtain eDNA from 15 different fish species, including both important consumption species, as well as species rarely or never recorded by conventional monitoring. We also detect eDNA from a rare vagrant species in the area; European pilchard (Sardina pilchardus). Additionally, we detect four bird species. Records in national databases confirmed the occurrence of all detected species. To investigate the efficiency of the eDNA approach, we compared its performance with 9 methods conventionally used in marine fish surveys. Promisingly, eDNA covered the fish diversity better than or equal to any of the applied conventional methods. Our study demonstrates that even small samples of seawater contain eDNA from a wide range of local fish species. Finally, in order to examine the potential dispersal of eDNA in oceans, we performed an experiment addressing eDNA degradation in seawater, which shows that even small (100-bp) eDNA fragments degrades beyond detectability within days. Although further studies are needed to validate the eDNA approach in varying environmental conditions, our findings provide a strong proof-of-concept with great perspectives for future monitoring of marine biodiversity and resources.

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.

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.

75 FR 67511 - Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for the Georgia...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-02

... Part III Department of the Interior Fish and Wildlife Service 50 CFR Part 17 Endangered and... THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R4-ES-2008-0104; MO 92210-0-0008... Habitat AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and...

Bull Trout Forage Investigations in Beulah Reservoir, Oregon - Annual Report for 2006

USGS Publications Warehouse

Rose, Brien P.; Mesa, Mathew G.

2009-01-01

Beulah Reservoir on the north fork of the Malheur River in northeastern Oregon provides irrigation water to nearby farms and ranches and supports an adfluvial population of bull trout (Salvelinus confluentus), which are listed as threatened under the Endangered Species Act. Water management in Beulah Reservoir results in seasonal and annual fluctuations of water volume that may affect forage availability for bull trout. Because no minimum pool requirements currently exist, the reservoir is occasionally reduced to run-of-river levels, which may decimate forage fish populations and ultimately affect bull trout. We sampled fish and aquatic insects in Beulah Reservoir in the spring, before the annual drawdown of 2006, and afterward, in the late fall. We also collected samples 1.5 years after the reservoir was dewatered for three consecutive summers. Overall, the moderate drawdown of 2006 (32 percent of full pool) did not drastically alter the fish community in Beulah Reservoir. We did document, however, decreases in abundance and sizes of chironomids in areas of the reservoir that were frequently dewatered, increased catch rates of fish with gillnets, and decreases in population estimates for smaller fishes after drawdown. In 2006, after the dewaterings of 2002-04, species composition was similar to that prior to the dewaterings, but the size distributions of most species were biased toward small juvenile or subyearling fishes and larger fishes were rare. Our results indicate that repeated reservoir drawdown reduces aquatic insect forage for bull trout and probably affects forage fish populations at least temporarily. The high catch rates of juvenile fishes 1.5 years after consecutive dewaterings suggests good reproductive success for any remaining adult fish, and shows that the fish community in Beulah Reservoir is resilient to such disturbances. There is, however, a period of time after serious drawdowns before significant numbers of juvenile fishes start to appear in the reservoir. Because Beulah Reservoir experiences a wide variety of drawdown scenarios in consecutive years, the forage fish community may never reach a state of equilibrium.

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 ...

Genetic variation in steelhead of Oregon and northern California

USGS Publications Warehouse

Reisenbichler, R.R.; McIntyre, J.D.; Solazzi, M.F.; Landino, S.W

1992-01-01

Steelhead Oncorhynchus mykiss from various sites between the Columbia River and the Mad River, California, were genetically characterized at 10 protein-coding loci or pairs of loci by starch gel electrophoresis. Fish from coastal streams differed from fish east of the Cascade Mountains and from fish of the Willamette River (a tributary of the Columbia River, west of the Cascade Mountains). Coastal steelhead from the northern part of the study area differed from those in the southern part. Genetic differentiation within and among drainages was not statistically significant; however, gene diversity analysis and the life history of steelhead suggested that fish from different drainages should be considered as separate populations. Genetic variation among fish in separate drainages was similar to that reported in northwestern Washington and less than that reported in British Columbia. Allele frequencies varied significantly among year-classes. Genetic variation within samples accounted for 98.3% of the total genetic variation observed in this study. Most hatchery populations differed from wild populations, suggesting that conservation of genetic diversity among and within wild populations could be facilitated by altering hatchery programs.

Biotic and abiotic influences on abundance and distribution of nonnative Chinook salmon and native ESA-listed steelhead in the Wind River, Washington

USGS Publications Warehouse

Jezorek, Ian G.; Connolly, Patrick J.

2015-01-01

Biotic and abiotic factors influence fish populations and distributions. Concerns have been raised about the influence of hatchery fish on wild populations. Carson National Fish Hatchery produces spring Chinook salmon Oncorhynchus tshawytscha in the Wind River, Washington, and some spawn in the river. Managers were concerned that Chinook salmon could negatively affect wild steelhead O. mykiss and that a self-sustaining population of Chinook salmon may develop. Our objectives were to assess: 1) the distribution and populations of juvenile spring Chinook salmon and juvenile steelhead in the upper Wind River; 2) the influence of stream flow and of each population on the other; and 3) if Chinook salmon populations were self-sustaining. We snorkeled to determine distribution and abundance. Flow in the fall influenced upstream distribution and abundance of juvenile Chinook salmon. Juvenile Chinook salmon densities were consistently low (range 0.0 to 5.7 fish 100 m-2) and not influenced by number of spawners, winter flow magnitude, or steelhead abundance. Juvenile steelhead were distributed through the study section each year. Age-0 and age-1 steelhead densities (age-0 range: 0.04 to 37.0 fish 100 m-2; age-1 range: 0.02 to 6.21 fish 100 m-2) were consistently higher than for juvenile Chinook salmon. Steelhead spawner abundance positively influenced juvenile steelhead abundance. During this study, Chinook salmon in the Wind River appear to have had little effect on steelhead. Low juvenile Chinook salmon abundance and a lack of a spawner-to-juvenile relationship suggest Chinook salmon are not self-sustaining and potential for such a population is low under current conditions.

Rainbow trout embryotoxicity of a complex contaminant mixture extracted from Lake Michigan lake trout

USGS Publications Warehouse

Wilson, P.J.; Tillitt, D.E.

1996-01-01

Persistent Hydrophobic contaminants such as poly chlorinated dibenzo-p-dioxins, dibenzofurans and biphenyl congeners are present in aquatic systems, and are known to produce adverse effects in fish. Reproductive failure in fish populations has been observed in aquatic systems contaminated with persistent hydrophobic compounds. In order to mimic maternal transfer of environmental contaminants to newly fertilized fish eggs, a complex environmental extract was tested for embryotoxicity in a nanoinjection bioassay with embryos of rainbow trout. The extract was obtained from whole adult lake trout collected from Lake Michigan in 1988. The tissue extraction involved blending and dehydration with sodium sulfate, column extraction, dialysis separation, reactive cleanup and, finally, high-performance gel permeation chromatography. Egg gram-equivalent doses (g tissue/g egg normalized for egg % lipid) of the final extract (0.02, 0.10, 0.20, 1.0, 2.0, 4.0, 10.0, 20.0 eggEQ) were injected into newly fertilized rainbow trout eggs using triolein as the vehicle. The extract of the lake trout was embryotoxic to rainbow trout, with an LD50 of 35 eggEQ, based on total cumulative mortality. Gross physical abnormalities characteristic of dioxin exposure, such as hemorrhaging, yolk-sac edema and craniofacial deformities, were observed and showed significant dose-related increases. Sublethal effects in the rainbow trout, such as delayed time to hatch, mild hemorrhaging and moderate yolk-sac edema, resulted from estimated total PCB exposure as low as 8.8 ng/g, and this may have significant implications on Great Lakes lake trout fry and juvenile mortality.

Water quality, physical habitat, and fish community composition in streams in the Twin Cities metropolitan area, Minnesota, 1997-98

USGS Publications Warehouse

Talmage, Philip J.; Lee, Kathy E.; Goldstein, Robert M.; Anderson, Jesse P.; Fallon, James D.

1999-01-01

Water quality, physical habitat, and fish-community composition were characterized at 13 Twin Cities metropolitan area streams during low-flow conditions, September 1997. Fish communities were resampled during September 1998. Sites were selected based on a range of human population density. Nutrient concentrations were generally low, rarely exceeding concentrations found in agricultural streams or water-quality criteria. Seventeen pesticides and five pesticide metabolites were detected, with atrazine being the only pesticide detected at all 13 streams. Colony counts of fecal coliform bacteria ranged from 54 to greater than 11,000 colonies per 100 mL. Instream fish habitat was sparse with little woody debris and few boulders, cobble, or other suitable fish habitat. Thirty-eight species and one hybrid from 10 families were collected. Fish communities were characterized by high percentages of omnivores and tolerant species with few intolerant species. Index of Biotic Integrity scores were low, with most streams rating fair to very poor. Percent impervious surface was positively correlated with sodium and chloride concentrations and human population density, but was negatively correlated with fish species richness and diversity. Urban land use and human population density influence fish communities and water quality in Twin Cities metropolitan area streams. Other factors that may influence fish community composition include percent impervious cover, water chemistry, water temperature, geomorphology, substrate, instream habitat, and migration barriers.

A fine-scale assessment of using barriers to conserve native stream salmonids: a case study in Akokala Creek, Glacier National Park, USA

USGS Publications Warehouse

Muhlfeld, Clint C.; D'Angelo, Vincent S.; S. T. Kalinowski,; Landguth, Erin L.; C. C. Downs,; J. Tohtz,; Kershner, Jeffrey L.

2012-01-01

Biologists are often faced with the difficult decision in managing native salmonids of where and when to install barriers as a conservation action to prevent upstream invasion of nonnative fishes. However, fine-scale approaches to assess long-term persistence of populations within streams and watersheds chosen for isolation management are often lacking. We employed a spatially-explicit approach to evaluate stream habitat conditions, relative abundance, and genetic diversity of native westslope cutthroat trout (Oncorhynchus clarkii lewisi) within the Akokala Creek watershed in Glacier National Park- a population threatened by introgressive hybridization with nonnative rainbow trout (O. mykiss) from nearby sources. The systematic survey of 24 stream reaches showed broad overlap in fish population and suitable habitat characteristics among reaches and no natural barriers to fish migration were found. Analysis of population structure using 16 microsatellite loci showed modest amounts of genetic diversity among reaches, and that fish from Long Bow Creek were the only moderately distinct genetic group. We then used this information to assess the potential impacts of three barrier placement scenarios on long-term population persistence and genetic diversity. The two barrier placement scenarios in headwater areas generally failed to meet general persistence criteria for minimum population size (2,500 individuals, Ne = 500), maintenance of long-term genetic diversity (He), and no population subdivision. Conversely, placing a barrier near the stream mouth and selectively passing non-hybridized, migratory spawners entering Akokala Creek met all persistence criteria and may offer the best option to conserve native trout populations and life history diversity. Systematic, fine-scale stream habitat, fish distribution, and genetic assessments in streams chosen for barrier installation are needed in conjunction with broader scale assessments to understand the potential impacts of using barriers for conservation of native salmonid populations threatened by nonnative fish invasions.

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. 

Identification of Saprolegnia Spp. Pathogenic in Chinook Salmon : Final Report.

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

Whisler, Howard C.

1997-06-01

This project has developed procedures to assess the role of the fungal parasite, Saprolegnia in the biology of salmon, particularly adult Chinook, in the Columbia River Basin. Both morphological and DNA ``fingerprinting`` surveys reveal that Saprolegnia parasitica (=S. diclina, Type I) is the most common pathogen of these fish. In the first phase of this study 92% of 620 isolates, from salmon lesions, conformed to this taxa of Saprolegnia. In the current phase, the authors have developed variants of DNA fingerprinting (RAPD and SWAPP analysis) that permit examination of the sub-structure of the parasite population. These results confirm the predominancemore » of S. parasitica, and suggest that at least three different sub-groups of this fungus occur in the Pacific N.W., USA. The use of single and paired primers with PCR amplification permits identification of pathogenic types, and distinction from other species of the genus considered to be more saprophytic in character. A year`s survey of saprolegniaceous fungi from Lake Washington indicated that the fish-pathogen was not common in the water column. Where and how fish encounter this parasite can be approached with the molecular tags identified in this project.« less

Spatial extent of analysis influences observed patterns of population genetic structure in a widespread darter species (Percidae)

USGS Publications Warehouse

Argentina, Jane E.; Angermeier, Paul L.; Hallerman, Eric M.; Welsh, Stuart A.

2018-01-01

Connectivity among stream fish populations allows for exchange of genetic material and helps maintain genetic diversity, adaptive potential and population stability over time. Changes in species demographics and population connectivity have the potential to permanently alter the genetic patterns of stream fish, although these changes through space and time are variable and understudied in small‐bodied freshwater fish.As a spatially widespread, common species of benthic freshwater fish, the variegate darter (Etheostoma variatum) is a model species for documenting how patterns of genetic structure and diversity respond to increasing isolation due to large dams and how scale of study may shape our understanding of these patterns. We sampled variegate darters from 34 sites across their range in the North American Ohio River basin and examined how patterns of genetic structure and diversity within and between populations responded to historical population changes and dams within and between populations.Spatial scale and configuration of genetic structure varied across the eight identified populations, from tributaries within a watershed, to a single watershed, to multiple watersheds that encompass Ohio River mainstem habitats. This multiwatershed pattern of population structuring suggests genetic dispersal across large distances was and may continue to be common, although some populations remain isolated despite no apparent structural dispersal barriers. Populations with low effective population sizes and evidence of past population bottlenecks showed low allelic richness, but diversity patterns were not related to watershed size, a surrogate for habitat availability. Pairwise genetic differentiation (FST) increased with fluvial distance and was related to both historic and contemporary processes. Genetic diversity changes were influenced by underlying population size and stability, and while instream barriers were not strong determinants of genetic structuring or loss of genetic diversity, they reduce population connectivity and may impact long‐term population persistence.The broad spatial scale of this study demonstrated the large spatial extent of some variegate darter populations and indicated that dispersal is more extensive than expected given the movement patterns typically observed for small‐bodied, benthic fish. Dam impacts depended on underlying population size and stability, with larger populations more resilient to genetic drift and allelic richness loss than smaller populations.Other darters that inhabit large river habitats may show similar patterns in landscape‐scale studies, and large river barriers may impact populations of small‐bodied fish more than previously expected. Estimation of dispersal rates and behaviours is critical to conservation of imperilled riverine species such as darters.

Coexistence in streams: Do source-sink dynamics allow salamanders to persist with fish predators?

USGS Publications Warehouse

Sepulveda, A.J.; Lowe, W.H.

2011-01-01

Theory suggests that source-sink dynamics can allow coexistence of intraguild predators and prey, but empirical evidence for this coexistence mechanism is limited. We used capture-mark-recapture, genetic methods, and stable isotopes to test whether source-sink dynamics promote coexistence between stream fishes, the intraguild predator, and stream salamanders (Dicamptodon aterrimus), the intraguild prey. Salamander populations from upstream reaches without fish were predicted to maintain or supplement sink populations in downstream reaches with fish. We found instead that downstream reaches with fish were not sinks even though fish consumed salamander larvae-apparent survival, recruitment, and population growth rate did not differ between upstream and downstream reaches. There was also no difference between upstream and downstream reaches in net emigration. We did find that D. aterrimus moved frequently along streams, but believe that this is a response to seasonal habitat changes rather than intraguild predation. Our study provides empirical evidence that local-scale mechanisms are more important than dispersal dynamics to coexistence of streams salamanders and fish. More broadly, it shows the value of empirical data on dispersal and gene flow for distinguishing between local and spatial mechanisms of coexistence. ?? 2011 Springer-Verlag.

Quantifying the impact of longline fisheries on adult survival in the black-footed albatross

USGS Publications Warehouse

Veran, S.; Gimenez, O.; Flint, E.; Kendall, W.L.; Doherty, P.F.; Lebreton, J.D.

2007-01-01

1. Industrial longline fishing has been suspected to impact upon black-footed albatross populations Phoebastria nigripes by increasing mortality, but no precise estimates of bycatch mortality are available to ascertain this statement. We present a general framework for quantifying the relationship between albatross population and longline fishing in absence of reliable estimates of bycatch rate. 2. We analysed capture?recapture data of a population of black-footed albatross to obtain estimates of survival probability for this population using several alternative models to adequately take into account heterogeneity in the recapture process. Instead of trying to estimate the number of birds killed by using various extrapolations and unchecked assumptions, we investigate the potential relationship between annual adult survival and several measures of fishing effort. Although we considered a large number of covariates, we used principal component analysis to generate a few uncorrelated synthetic variables from the set and thus we maintained both power and robustness. 3. The average survival for 1997?2002 was 92%, a low value compared to estimates available for other albatross species. We found that one of the synthetic variables used to summarize industrial longline fishing significantly explained more than 40% of the variation in adult survival over 11 years, suggesting an impact by longline fishing on albatross? survival. 4. Our analysis provides some evidence of non-linear variation in survival with fishing effort. This could indicate that below a certain level of fishing effort, deaths due to incidental catch can be partially or totally compensated for by a decrease in natural mortality. Another possible explanation is the existence of a strong interspecific competition for accessing the baits, reducing the risk of being accidentally hooked. 5. Synthesis and applications. The suspicion of a significant impact of longline fishing on the black-footed albatross population was supported by the combination of a low estimate of adult survival for the study period, and a significant relationship between adult survival and a synthetic measure of fishing effort. This study highlights the sensitivity of the black-footed albatross to commercial longline fishing, and should exhort fishery management authorities to find adequate seabirds avoidance methods and to encourage their employment.

Parasites as biological tags of fish stocks: a meta-analysis of their discriminatory power.

PubMed

Poulin, Robert; Kamiya, Tsukushi

2015-01-01

The use of parasites as biological tags to discriminate among marine fish stocks has become a widely accepted method in fisheries management. Here, we first link this approach to its unstated ecological foundation, the decay in the similarity of the species composition of assemblages as a function of increasing distance between them, a phenomenon almost universal in nature. We explain how distance decay of similarity can influence the use of parasites as biological tags. Then, we perform a meta-analysis of 61 uses of parasites as tags of marine fish populations in multivariate discriminant analyses, obtained from 29 articles. Our main finding is that across all studies, the observed overall probability of correct classification of fish based on parasite data was about 71%. This corresponds to a two-fold improvement over the rate of correct classification expected by chance alone, and the average effect size (Zr = 0·463) computed from the original values was also indicative of a medium-to-large effect. However, none of the moderator variables included in the meta-analysis had a significant effect on the proportion of correct classification; these moderators included the total number of fish sampled, the number of parasite species used in the discriminant analysis, the number of localities from which fish were sampled, the minimum and maximum distance between any pair of sampling localities, etc. Therefore, there are no clear-cut situations in which the use of parasites as tags is more useful than others. Finally, we provide recommendations for the future usage of parasites as tags for stock discrimination, to ensure that future applications of the method achieve statistical rigour and a high discriminatory power.

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...

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,...

Species composition and dietary relationships in a brackish shallow water fish assemblage in the Bothnian Sea, Sweden

NASA Astrophysics Data System (ADS)

Thorman, Staffan; Wiederholm, Anne-Marie

1984-09-01

A nearshore fish assemblage inhabiting a shallow bay in the southern Bothnian Sea, Sweden, with demanding environmental conditions (c. 5‰; >15°C during 4 months 1980 and 1 month 1981) was studied during a two-year period, in 1980 and 1981. Seasonal distribution patterns, dietary relationships, and growth rates were studied in Pungitius pungitius (L.), Pomatoschistus minutus (Pallas.), Gasterosteus aculeatus (L.), Phoxinus phoxinus (L.), Pomatoschistus microps (Krøyer) and Gobius niger L. The structure of the juvenile populations changed both over seasons and years but the adult populations remained constant. Lower water temperature, fewer individuals, lower and delayed fish growth, and lower interspecific food overlaps were found in 1981 compared to 1980. Few significant correlations were found in both years between the following community parameters: diversity, niche width, food overlap, and the proportion of each species in the fish assemblage. According to these results it is suggested that food competition and resource partitioning were of minor importance for the structuring of the fish community in the present area. Rather, the extreme salinity and the fluctuations in temperature regulated the fish populations. One may conclude that the populations of juveniles were more influenced by short-term changes in the environment than those of the adults.

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

Fish consumption and socio-economic factors among residents of Arkhangelsk city and the rural Nenets autonomous area.

PubMed

Petrenya, Natalia; Dobrodeeva, Liliya; Brustad, Magritt; Bichkaeva, Fatima; Menshikova, Elena; Lutfalieva, Gulnara; Poletaeva, Anna; Repina, Veronika; Cooper, Marie; Odland, Jon Øyvind

2011-02-01

The urban Russian and the rural Indigenous populations in the Russian European North have different lifestyles, living conditions and food supplies. The objective of this study was to investigate and compare fish consumption in relation to the socio-economic characteristics of 2 communities in Arkhangelsk County. A cross-sectional study. In total, 166 adults (83.1% women) from Arkhangelsk city and 134 adults (80.6% women) from the village of Nelmin-Nos (of which 88.9% are Indigenous people, Nenets), in the Nenets Autonomous Area (NAO), attended a health screening. The screening included a physical examination, blood sampling and a questionnaire. The populations studied had different socio-economic characteristics. In the rural NAO group, education levels were lower, the number of full-time employees was less, the percentage of persons with low monthly income was higher and the number of children per household was higher when compared to the Arkhangelsk group. The median total fish intake was 48.8 g/day for Arkhangelsk city and 27.1 g/day for Nelmin-Nos (p=0.009). Locally caught whitefish constituted a major part of the total fish consumption in Nelmin-Nos, while lean marine fish species were rarely eaten. Cod and cod-family fish species were often consumed by residents of Arkhangelsk city (p < 0.001). Fish consumption was positively related to monthly income. The frequency of fishing in the respondents from the Nelmin-Nos group predicted their fish consumption. Monthly income had a significant influence on fish intake in both study populations from Northern Russia. Fishing seems to be an important factor for predicting fish consumption in the residents of the rural NAO.

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 ...

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

Fish distribution during smolt migration in the Penobscot Estuary, ME

NASA Astrophysics Data System (ADS)

Volkel, S. L.

2016-02-01

Estuaries are complex and dynamic ecosystems. The Penobscot Estuary is particularly important because it harbors a suite of imperiled diadromous fish species. In order to properly manage these populations, it is imperative to understand their distribution and ecology. My study focuses on May because endangered Atlantic salmon migrate seaward then. Successful emigration of these smolts is important to the population's overall fitness. One potential way to increase the likelihood of migratory success (survival) is to decrease their risk of predation. Assuming that predators in this system are generalists, overall smolt predation may be reduced by having a larger selection of alternative prey (other fish species). We hypothesize that diadromous fish abundance is increasing as a result of recent (2012-2013) dam removals. To explore this hypothesis, I used hydroacoustic methods to characterize the distribution patterns of alternative prey (TL=10-30 cm). I found that peak fish abundances occurred in the mid-estuary, especially during mid-May, and depth distribution patterns varied weekly. By understanding these seasonal, longitudinal, and vertical distribution patterns, I explored potential interactions of other fish populations as prey buffers to emigrating smolts.

Applications of bioenergetics models to fish ecology and management: where do we go from here?

USGS Publications Warehouse

Hansen, Michael J.; Boisclair, Daniel; Brandt, Stephen B.; Hewett, Steven W.; Kitchell, James F.; Lucas, Martyn C.; Ney, John J.

1993-01-01

Papers and panel discussions given during a 1992 symposium on bioenergetics models are summarized. Bioenergetics models have been applied to a variety of research and management questions related to fish stocks, populations, food webs, and ecosystems. Applications include estimates of the intensity and dynamics of predator-prey interactions, nutrient cycling within aquatic food webs of varying trophic structure, and food requirements of single animals, whole populations, and communities of fishes. As tools in food web and ecosystem applications, bioenergetics models have been used to compare forage consumption by salmonid predators across the Laurentian Great Lakes for single populations and whole communities, and to estimate the growth potential of pelagic predators in Chesapeake Bay and Lake Ontario. Some critics say that bioenergetics models lack sufficient detail to produce reliable results in such field applications, whereas others say that the models are too complex to be useful tools for fishery managers. Nevertheless, bioenergetics models have achieved notable predictive successes. Improved estimates are needed for model parameters such as metabolic costs of activity, and more complete studies are needed of the bioenergetics of larval and juvenile fishes. Future research on bioenergetics should include laboratory and field measurements of key model parameters such as weight-dependent maximum consumption, respiration and activity, and thermal habitats actually occupied by fish. Future applications of bioenergetics models to fish populations also depend on accurate estimates of population sizes and survival rates.

Consequences of extreme life history traits on population persistence: do short-lived gobies face demographic bottlenecks?

NASA Astrophysics Data System (ADS)

Lefèvre, Carine D.; Nash, Kirsty L.; González-Cabello, Alonso; Bellwood, David R.

2016-06-01

The majority of coral reef goby species are short-lived, with some highly abundant species living less than 100 d. To understand the role and consequences of this extreme life history in shaping coral reef fish populations, we quantitatively documented the structure of small reef fish populations over a 26-month period (>14 short-lived fish generations) at an inshore reef on the Great Barrier Reef, Australia. Most species with life spans >1 yr, such as pomacentrids, exhibited a peak in recruitment during the austral summer, driving seasonal changes in the small fish community composition. In contrast, there were no clear changes in goby community composition, despite the abundance of short-lived, high turnover species. Species of Eviota, the most abundant gobiid genus observed, showed remarkably similar demographic profiles year-round, with consistent densities of adults as well as recently recruited juveniles. Our results demonstrate ongoing recruitment of these small cryptic fishes, which appears to compensate for an exceptionally short life span on the reef. Our results suggest that gobiid populations are able to overcome demographic limitations, and by maintaining reproduction, larval survival and recruitment throughout the year, they may avoid population bottlenecks. These findings also underline the potential trophodynamic importance of these small species; because of this constant turnover, Eviota species and other short-lived fishes may be particularly valuable contributors to the flow of energy on coral reefs, underpinning the year-round trophic structure.

Size selection from fishways and potential evolutionary responses in a threatened Atlantic salmon population

USGS Publications Warehouse

Maynard, George A.; Kinnison, M.T.; Zydlewski, Joseph D.

2017-01-01

The evolutionary effects of harvest on wild fish populations have been documented around the world; however, sublethal selective pressures can also cause evolutionary changes in phenotypes. For migratory fishes, passage facilities may represent instances of nonlethal selective pressure. Our analysis of 6 years of passage data suggests that certain fish passage facilities on the Penobscot River have been exerting selective pressure against large-bodied, anadromous Atlantic salmon (Salmo salar). At the second and third dams in the river, a 91-cm salmon was 21%–27% and 12%–16% less likely to pass than a 45-cm salmon, respectively. Fish size positively influences egg survival and number and is a heritable trait. Therefore, in a wild-reproducing population, exclusion of large fish from spawning areas may have population-level impacts. In the Penobscot River, most returning adults derive from a hatchery program that collects its broodstock after passing the first dam in the river. Analysis of fork lengths of salmon returning to the Penobscot River from 1978 to 2012 provided mixed support for evolution of size at maturity in different age classes in a pattern that may be expected from interactions with conservation hatchery operations. Additionally, slow-maturing and iteroparous individuals that represent the largest salmon size classes were essentially lost from the population during that time, and Penobscot River fish have shorter fork lengths at maturity than Atlantic salmon in undammed systems.

Managing for desired experiences and site preferences: the case of fee-fishing anglers.

PubMed

Schuett, Michael A; Pierskalla, Chad D

2007-02-01

Fee-fishing involves paying a fee for the privilege of fishing a body of water where fish populations are enhanced by stocking fish. Past literature on this activity has focused more on the operation of the enterprise and management of the fish than the people and site characteristics. The objectives of the study were to profile anglers and describe their site/management preferences. This study utilized an on-site interview and mail-back questionnaire at fee-fishing establishments in West Virginia (n = 212). Factor analysis of desired recreation experiences yielded five factors: Experience nature & adventure, Stress release & relaxation, Trophy fishing, Escape, and Family time. Cluster analysis showed that these anglers can be segmented into two distinct clusters, differing by sociodemographic characteristics, fishing behavior, and site/management preferences. The findings from this study provide baseline data to aid public resource managers and fee-fishing business owners in determining how to provide satisfying outdoor experiences and deliver desired services on-site. Future research will be needed from additional fee-fishing sites to obtain more detail about this outdoor recreation cohort and be able to generalize to a larger population of participants.

Managing for Desired Experiences and Site Preferences: The Case of Fee-Fishing Anglers

NASA Astrophysics Data System (ADS)

Schuett, Michael A.; Pierskalla, Chad D.

2007-02-01

Fee-fishing involves paying a fee for the privilege of fishing a body of water where fish populations are enhanced by stocking fish. Past literature on this activity has focused more on the operation of the enterprise and management of the fish than the people and site characteristics. The objectives of the study were to profile anglers and describe their site/management preferences. This study utilized an on-site interview and mail-back questionnaire at fee-fishing establishments in West Virginia ( n = 212). Factor analysis of desired recreation experiences yielded five factors: Experience nature & adventure, Stress release & relaxation, Trophy fishing, Escape, and Family time. Cluster analysis showed that these anglers can be segmented into two distinct clusters, differing by sociodemographic characteristics, fishing behavior, and site/management preferences. The findings from this study provide baseline data to aid public resource managers and fee-fishing business owners in determining how to provide satisfying outdoor experiences and deliver desired services on-site. Future research will be needed from additional fee-fishing sites to obtain more detail about this outdoor recreation cohort and be able to generalize to a larger population of participants.

Spatial fishing restrictions benefit demersal stocks in the northeastern Mediterranean Sea.

PubMed

Dimarchopoulou, Donna; Dogrammatzi, Aikaterini; Karachle, Paraskevi K; Tsikliras, Athanassios C

2018-04-13

The multi-level benefits that marine organisms gain when protected from fishing are well acknowledged. Here, we investigated the effects of a 40-year trawling ban on the status of targeted and non-targeted marine species within a major fishing ground in the northeastern Mediterranean Sea (Thermaikos Gulf, Aegean Sea). Biomass and somatic length of fish and invertebrates (six commercial and three non-commercial demersal species) were measured in three areas of varying fishing pressure, depending on the temporal and spatial operational regimes of fishing vessels. The positive effects of fishing restrictions on the studied demersal stocks were clearly revealed, as the commercial fish species exhibited higher biomass in the intermediate and low pressure areas, as well as increasing maximum and mean total length (and other length indicators) with decreasing fishing effort. The mean total length of non-commercial species generally did not differ among areas, except for species caught and discarded at high rates. The present study shows that fishing does alter the population structure and biomass of commercial demersal species, and that fishing restrictions greatly contribute to improving the status of demersal populations within the restricted areas by providing a refuge for large individuals and their important contribution to the gene pool.

Assessment of tolerant sunfish populations (Lepomis sp.) inhabiting selenium-laden coal ash effluents. 1. Hematological and population level assessment.

PubMed

Lohner, T W; Reash, R J; Willet, V E; Rose, L A

2001-11-01

Sunfish were collected from coal ash effluent-receiving streams and Ohio River watershed reference sites to assess the effects of exposure to low-level selenium concentrations. Selenium, copper, and arsenic concentrations were statistically higher in tissue samples from exposed fish than in reference fish. Leukopenia, lymphocytosis, and neutropenia were evident in exposed fish and were indicative of metal exposure and effect. White blood cell counts and percent lymphocyte values were significantly correlated with liver selenium concentrations. Plasma protein levels were significantly lower in exposed fish than in fish from the Ohio River, indicating that exposed fish may have been nutritionally stressed. Condition factors for fish from the ash pond-receiving streams were the same as, or lower than, those of fish from the reference sites. There was no evidence that the growth rate of fish in the receiving streams differed from that of fish in the reference streams. Despite liver selenium concentrations which exceeded reported toxicity thresholds and evidence of significant hematological changes, there were no significant differences in fish condition factors, liver-somatic indices, or length-weight regressions related to selenium.

75 FR 28816 - Guam National Wildlife Refuge, Yigo, Guam

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-24

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R1-R-2009-N221; 10137-1265-0000 S3] Guam National Wildlife Refuge, Yigo, Guam AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of.... Fish and Wildlife Service (Service), announce the availability of our final comprehensive conservation...

Distribution of the Luminous Bacterium Beneckea harveyi in a Semitropical Estuarine Environment

PubMed Central

O'Brien, Catherine H.; Sizemore, Ronald K.

1979-01-01

Bioluminescent bacteria were found in the water column, sediment, shrimp, and gastrointestinal tract of marine fishes from the semitropical estuarine environment of the East Lagoon, Galveston Island, Tex. Populations in the water column decreased during cold weather while sedimentary populations persisted. The highest percentages of luminous organisms were isolated from the gastrointestinal tract of marine fishes, where they persisted during 5 days of starvation. The presence of chitin temporarily increased intestinal populations. All isolates were Beneckea harveyi, whose natural habitat appears to be the gut of fishes and whose free-living reservoir appears to be marine sediments. PMID:16345465

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.

Qualitative modelling of gold mine impacts on Lihir Island's socioeconomic system and reef-edge fish community.

PubMed

Dambacher, Jeffrey M; Brewer, David T; Dennis, Darren M; Macintyre, Martha; Foale, Simon

2007-01-15

Inhabitants of Lihir Island, Papua New Guinea, have traditionally relied on reef fishing and rotational farming of slash-burn forest plots for a subsistence diet. However, a new gold mine has introduced a cash economy to the island's socioeconomic system and impacted the fringing coral reef through sedimentation from the near-shore dumping of mine wastes. Studies of the Lihirian people have documented changes in population size, local customs, health, education, and land use; studies of the reef have documented impacts to fish populations in mine affected sites. Indirect effects from these impacts are complex and indecipherable when viewed only from isolated studies. Here, we use qualitative modelling to synthesize the social and biological research programs in order to understand the interaction of the human and ecological systems. Initial modelling results appear to be consistent with differences in fish and macroalgae populations in sites with and without coral degradation due to sedimentation. A greater cash flow from mine expansion is predicted to increase the human population, the intensity of the artisanal fishery, and the rate of sewage production and land clearing. Modelling results are being used to guide ongoing research projects, such as monitoring fish populations and artisanal catch and patterns and intensity of land clearing.

Evolutionary Responses to Invasion: Cane Toad Sympatric Fish Show Enhanced Avoidance Learning

PubMed Central

Caller, Georgina; Brown, Culum

2013-01-01

The introduced cane toad (Bufo marinus) poses a major threat to biodiversity due to its lifelong toxicity. Several terrestrial native Australian vertebrates are adapting to the cane toad’s presence and lab trials have demonstrated that repeated exposure to B. marinus can result in learnt avoidance behaviour. Here we investigated whether aversion learning is occurring in aquatic ecosystems by comparing cane toad naïve and sympatric populations of crimson spotted rainbow fish (Melanotaenia duboulayi). The first experiment indicated that fish from the sympatric population had pre-existing aversion to attacking cane toad tadpoles but also showed reduced attacks on native tadpoles. The second experiment revealed that fish from both naïve and sympatric populations learned to avoid cane toad tadpoles following repeated, direct exposure. Allopatric fish also developed a general aversion to tadpoles. The aversion learning abilities of both groups was examined using an experiment involving novel distasteful prey items. While both populations developed a general avoidance of edible pellets in the presence of distasteful pellets, only the sympatric population significantly reduced the number of attacks on the novel distasteful prey item. These results indicate that experience with toxic prey items over multiple generations can enhance avoidance leaning capabilities via natural selection. PMID:23372788

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 erratic and variable than population growth in the Coosa River. We encourage ecologists to develop similar models for other lotic species, particularly in regulated river systems. Successful management of fish populations in regulated systems requires that we are able to predict how hydrology affects recruitment and will ultimately influence the population dynamics of fishes.

Using high-resolution satellite imagery to assess populations of animals in the Antarctic

NASA Astrophysics Data System (ADS)

LaRue, Michelle Ann

The Southern Ocean is one of the most rapidly-changing ecosystems on the planet due to the effects of climate change and commercial fishing for ecologically-important krill and fish. It is imperative that populations of indicator species, such as penguins and seals, be monitored at regional- to global scales to decouple the effects of climate and anthropogenic changes for appropriate ecosystem-based management of the Southern Ocean. Remotely monitoring populations through high-resolution satellite imagery is currently the only feasible way to gain information about population trends of penguins and seals in Antarctica. In my first chapter, I review the literature where high-resolution satellite imagery has been used to assess populations of animals in polar regions. Building on this literature, my second chapter focuses on estimating changes in abundance in the Weddell seal population in Erebus Bay. I found a strong correlation between ground and satellite counts, and this finding provides an alternate method for assessing populations of Weddell seals in areas where less is known about population status. My third chapter explores how size of the guano stain of Adelie penguins can be used to predict population size. Using high-resolution imagery and ground counts, I built a model to estimate the breeding population of Adelie penguins using a supervised classification to estimate guano size. These results suggest that the size of guano stain is an accurate predictor of population size, and can be applied to estimate remote Adelie penguin colonies. In my fourth chapter, I use air photos, satellite imagery, climate and mark-resight data to determine that climate change has positively impacted the population of Adelie penguins at Beaufort Island through a habitat release that ultimately affected the dynamics within the southern Ross Sea metapopulation. Finally, for my fifth chapter I combined the literature with observations from aerial surveys and satellite imagery to determine that emperor penguins are not philopatric. These results have implications for interpreting long-term modeling studies and I suggest that future research should account for metapopulation dynamics within emperor penguin populations. Combined, my dissertation provides resources and new insights for effective management of the Southern Ocean ecosystem.

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...

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

USGS Publications Warehouse

Dunham, J.B.; Young, M.; Gresswell, Robert E.; Rieman, B.

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 vulnerability of fish to fire is contingent upon the quality of affected habitats, the amount and distribution of habitat (habitat fragmentation), and habitat specificity of the species in question. Species with narrow habitat requirements in highly degraded and fragmented systems are likely to be most vulnerable to fire and fire-related disturbance. In addition to effects of fire on native fish, there are growing concerns about the effects of fire on nonnative fish invasions. The role of fire in facilitating invasions by nonnative fishes is unknown, but experience with other species suggests some forms of disturbance associated with fire may facilitate invasion. Management efforts to promote persistence of fishes in fire-prone landscapes can take the form of four basic alternatives: (1) pre-fire management; (2) post-fire management; (3) managing fire itself (e.g. fire fighting); and (4) monitoring and adaptive management. Among these alternatives, pre-fire management is likely to be most effective. Effective pre-fire management activities will address factors that may render fish populations more vulnerable to the effects of fire (e.g. habitat degradation, fragmentation, and nonnative species). Post-fire management is also potentially important, but suffers from being a reactive approach that may not address threats in time to avert them. Managing fire itself can be important in some contexts, but negative consequences for fish populations are possible (e.g. toxicity of fire fighting chemicals to fish). Monitoring and adaptive management can provide important new information for evaluating alternatives, but proper implementation is often hampered by inadequate study designs and inconsistent financial and institutional support. The challenge for providing better management guidelines will be to add solid empirical data and models to assess the relevance of emerging concepts and theories, and provide a sense of where and when fires pose significant risks and/or benefits to fishes.

Consequences of cannibalism and competition for food in a smallmouth bass population: An individual-based modeling study

USGS Publications Warehouse

Dong, Q.; DeAngelis, D.L.

1998-01-01

We used an individual-based modeling approach to study the consequences of cannibalism and competition for food in a freshwater fish population. We simulated the daily foraging, growth, and survival of the age-0 fish and older juvenile individuals of a sample population to reconstruct patterns of density dependence in the age-0 fish during the growth season. Cannibalism occurs as a part of the foraging process. For age-0 fish, older juvenile fish are both potential cannibals and competitors of food. We found that competition and cannibalism produced intraclass and interclass density dependence. Our modeling results suggested the following. (1) With low density of juvenile fish and weak interclass interactions, the age-0 fish recruitment shows a Beverton-Holt type of density dependence. (2) With high density of juvenile fish and strong interclass interactions, the age-0 fish recruitment shows a Ricker type of density dependence, and overcompensation occurs. (3) Interclass competition of food is responsible for much of the overcompensation. (4) Cannibalism intensifies the changes in the recruitment that are brought about by competition. Cannibalism can (a) generally reduce the recruitment, (b) particularly reduce the maximum level of recruitment, (c) cause overcompensation to occur at lower densities, and (d) produce a stronger overcompensation. (5) Growth is also a function of density. Cannibalism generally improves average growth of cannibals. (6) Variation in the lengths of age-0 fish increases with density and with a decreased average growth. These results imply that cannibalism and competition for food could strongly affect recruitment dynamics. Our model also showed that the rate of cannibalism either could be fairly even through the whole season or could vary dramatically. The individual-based modeling approach can help ecologists understand the mechanistic connection between daily behavioral and physiological processes operating at the level of individual organisms and seasonal patterns of population structure and dynamics. ?? Copyright by the American Fisheries Society 1998.

Persistence and diversity of directional landscape connectivity improves biomass pulsing in expanding and contracting wetlands

USGS Publications Warehouse

Yurek, Simeon; DeAngelis, Donald L.; Trexler, Joel C.; Klassen, Stephen; Larsen, Laurel G.

2016-01-01

In flood-pulsed ecosystems, hydrology and landscape structure mediate transfers of energy up the food chain by expanding and contracting in area, enabling spatial expansion and growth of fish populations during rising water levels, and subsequent concentration during the drying phase. Connectivity of flooded areas is dynamic as waters rise and fall, and is largely determined by landscape geomorphology and anisotropy. We developed a methodology for simulating fish dispersal and concentration on spatially-explicit, dynamic floodplain wetlands with pulsed food web dynamics, to evaluate how changes in connectivity through time contribute to the concentration of fish biomass that is essential for higher trophic levels. The model also tracks a connectivity index (DCI) over different compass directions to see if fish biomass dynamics can be related in a simple way to topographic pattern. We demonstrate the model for a seasonally flood-pulsed, oligotrophic system, the Everglades, where flow regimes have been greatly altered. Three dispersing populations of functional fish groups were simulated with empirically-based dispersal rules on two landscapes, and two twelve-year time series of managed water levels for those areas were applied. The topographies of the simulations represented intact and degraded ridge-and-slough landscapes (RSL). Simulation results showed large pulses of biomass concentration forming during the onset of the drying phase, when water levels were falling and fish began to converge into the sloughs. As water levels fell below the ridges, DCI declined over different directions, closing down dispersal lanes, and fish density spiked. Persistence of intermediate levels of connectivity on the intact RSL enabled persistent concentration events throughout the drying phase. The intact landscape also buffered effects of wet season population growth. Water level reversals on both landscapes negatively affected fish densities by depleting fish populations without allowing enough time for them to regenerate. Testable, spatiotemporal predictions of the timing, location, duration, and magnitude of fish concentration pulses were produced by the model, and can be applied to restoration planning.

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

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 assessment methods, to obtain robust estimates of population trends in species threatened by overfishing.

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 assessment methods, to obtain robust estimates of population trends in species threatened by overfishing. PMID:21966402

Population characteristics and the influence of discharge on Bluehead Sucker and Flannelmouth Sucker

USGS Publications Warehouse

Klein, Zachary B.; Breen, Matthew J.; Quist, Michael C.

2017-01-01

Rivers are among some of the most complex and important ecosystems in the world. Unfortunately, many fishes endemic to rivers have suffered declines in abundance and distribution suggesting that alterations to lotic environments have negatively influenced native fish populations. Of the 35 fishes native to the Colorado River basin (CRB), seven are considered either endangered, threatened, or species of special concern. As such, the conservation of fishes native to the CRB is a primary interest for natural resource management agencies. One of the major factors limiting the conservation and management of fishes endemic to the CRB is the lack of basic information on their ecology and population characteristics. We sought to describe the population dynamics and demographics of three populations of Bluehead Suckers (Catostomus discobolus) and Flannelmouth Suckers (C. latipinnis) in Utah. Additionally, we evaluated the potential influence of altered flow regimes on the recruitment and growth of Bluehead Suckers and Flannelmouth Suckers. Mortality of Bluehead Suckers and Flannelmouth Suckers from the Green, Strawberry, and White rivers was comparable to other populations. Growth of Bluehead Suckers and Flannelmouth Suckers was higher in the Green, Strawberry, and White rivers when compared to other populations in the CRB. Similarly, recruitment indices suggested that Bluehead Suckers and Flannelmouth Suckers in the Green, Strawberry, and White rivers had more stable recruitment than other populations in the CRB. Models relating growth and recruitment to hydrological indices provided little explanatory power. Notwithstanding, our results indicate that Bluehead Suckers and Flannelmouth Suckers in the Green, Strawberry, and White rivers represent fairly stable populations and provide baseline information that will be valuable for the effective management and conservation of the species.

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.

Yakima Fisheries Project : Final Environmental Impact Statement.

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

United States. Bonneville Power Administration; Washington; Confederated Tribes and Bands of the Yakama Nation, Washington.

1996-01-01

BPA proposes to fund several fishery-related activities in the Yakima River Basin. These activities, known as the Yakima Fisheries Project (YFP), would be jointly managed by the State of Washington and the Yakima Indian Nation. The YFP is included in the Northwest Power Planning Council`s (Council`s) fish and wildlife program. The Council selected the Yakima River system for attention because fisheries resources are severely reduced from historical levels and because there is a significant potential for enhancement of these resources. BPA`s proposed action is to fund (1) information gathering on the implementation of supplementation techniques and on feasibility of reintroducingmore » coho salmon in an environment where native populations have become extinct; (2) research activities based on continuous assessment, feedback and improvement of research design and activities ({open_quotes}adaptive management{close_quotes}); and (3) die construction, operation, and maintenance of facilities for supplementing populations of upper Yakima spring chinook salmon. Examined in addition to No Action are two alternatives for action: (1) supplementation of depressed natural populations of upper Yakima spring chinook and (2) that same supplementation plus a study to determine the feasibility of reestablishing naturally spawning population and a significant fall fishery for coho in the Yakima Basin. Alternative 2 is the preferred action. A central hatchery would be built for either alternative, as well as three sites with six raceways each for acclimation and release of spring chinook smolts. Major issues examined in the Revised Draft EIS include potential impacts of the project on genetic and ecological resources of existing fish populations, on water quality and quantity, on threatened and endangered species listed under the Endangered Species Act, and on the recreational fishery.« less

Development of a novel colorimetric sensor based on alginate beads for monitoring rainbow trout spoilage.

PubMed

Majdinasab, Marjan; Hosseini, Seyed Mohammad Hashem; Sepidname, Marziyeh; Negahdarifar, Manizheh; Li, Peiwu

2018-05-01

Alginate is a non-toxic, renewable, and linear copolymer obtained from the brown algae Laminaria digitata that can be easily shaped into beads. Its good gel forming properties have made it useful for entrapping food and pharmaceutical ingredients. In this study, alginate beads were used in a novel application as a colorimetric sensor in food intelligent packaging. Colorimetric sensor was developed through entrapping red cabbage extract as a pH indicator in alginate beads. The pH indicator beads were used in rainbow trout packaging for monitoring fillets spoilage. Color change of beads during fish storage was measured using the CIELab method. The alginate bead colorimetric sensor is validated by measuring total volatile basic nitrogen (TVB-N) levels and microbial populations in fish samples. Moreover, peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were evaluated during storage. Results indicated that increasing the bacterial population during storage and production of proteolytic enzymes resulted in protein degradation, accumulation of volatile amine compounds, increase in the pH and finally color change of alginate beads. The values of TVB-N, pH, PV and TBARS increased with time of storage. The results of TVB-N and microbial growth were in accordance with color change of beads and CIELab data. Therefore, the proposed system enjoys a high sensitivity to pH variations and is capable of monitoring the spoilage of fish or other protein-rich products through its wide range of color changes. The alginate beads containing the red cabbage extract can, thus, be used as a low-cost colorimetric sensor for intelligent packaging applications.

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.

Composition of Bacterial Communities Associated with Aurelia aurita Changes with Compartment, Life Stage, and Population

PubMed Central

Weiland-Bräuer, Nancy; Neulinger, Sven C.; Pinnow, Nicole; Künzel, Sven; Baines, John F.

2015-01-01

The scyphozoan Aurelia aurita is recognized as a key player in marine ecosystems and a driver of ecosystem change. It is thus intensely studied to address ecological questions, although its associations with microorganisms remain so far undescribed. In the present study, the microbiota associated with A. aurita was visualized with fluorescence in situ hybridization (FISH) analysis, and community structure was analyzed with respect to different life stages, compartments, and populations of A. aurita by 16S rRNA gene amplicon sequencing. We demonstrate that the composition of the A. aurita microbiota is generally highly distinct from the composition of communities present in ambient water. Comparison of microbial communities from different developmental stages reveals evidence for life stage-specific community patterns. Significant restructuring of the microbiota during strobilation from benthic polyp to planktonic life stages is present, arguing for a restructuring during the course of metamorphosis. Furthermore, the microbiota present in different compartments of the adult medusa (exumbrella mucus and gastric cavity) display significant differences, indicating body part-specific colonization. A novel Mycoplasma strain was identified in both compartment-specific microbiota and is most likely present inside the epithelium as indicated by FISH analysis of polyps, indicating potential endosymbiosis. Finally, comparison of polyps of different populations kept under the same controlled laboratory conditions in the same ambient water showed population-specific community patterns, most likely due the genetic background of the host. In conclusion, the presented data indicate that the associated microbiota of A. aurita may play important functional roles, e.g., during the life cycle. PMID:26116680

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…

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.

Movement patterns and spatial segregation of two populations of lake trout Salvelinus namaycush in Lake Huron

USGS Publications Warehouse

Binder, Thomas; Marsden, J. Ellen; Riley, Stephen; Johnson, James E.; Johnson, Nicholas; He, Ji; Ebener, Mark P.; Holbrook, Christopher; Bergstedt, Roger A.; Bronte, Charles R.; Hayden, Todd A.; Krueger, Charles C.

2017-01-01

Movement ecology is an important component of life history and population dynamics, and consequently its understanding can inform successful fishery management decision-making. While lake trout populations in Lake Huron have shown signs of recovery from near extinction in recent years, knowledge of their movement behavior remains incomplete. We used acoustic telemetry to describe and compare movement patterns of two Lake Huron lake trout populations: Drummond Island and Thunder Bay. Both populations showed high spawning site fidelity, with no evidence of co-mingling during non-spawning season. Detections between spawning periods were mainly limited to receivers within 100 km of spawning locations, and suggested that the two populations likely remained segregated throughout the year. Drummond Island fish, which spawn inside the Drummond Island Refuge, primarily dispersed east into Canadian waters of Lake Huron, with 79–92% of fish being detected annually on receivers outside the refuge. In contrast, Thunder Bay fish tended to disperse south towards Saginaw Bay. Large proportions (i.e., > 80%) of both populations were available to fisheries outside the management zone containing their spawning location. Thunder Bay fish moved relatively quickly to overwinter habitat after spawning, and tended to repeat the same post-spawning movement behavior each year. The consistent, predictable movement of both populations across management zones highlights the importance of understanding population dynamics to effective management of Lake Huron lake trout.

Fish consumption is inversely associated with male lung cancer mortality in countries with high levels of cigarette smoking or animal fat consumption.

PubMed

Zhang, J; Temme, E H; Kesteloot, H

2000-08-01

A striking difference in fish consumption and lung cancer mortality (LCM) exists among populations worldwide. This study investigated the relation between fish consumption and LCM at the population level. Sex-specific LCM data, mostly around 1993 and fish consumption data for 10 periods 1961-1994 in 36 countries were obtained from WHO and FAO, respectively. A significant inverse correlation exists between log fish consumption and LCM rate in 9 out of the 10 time periods (r = -0.34 to r = -0.46, P = 0.044 to P = 0.005). After adjusting for smoking and other confounders, log fish consumption (% of total energy [% E]) was inversely and significantly associated with LCM rate (per 100 000 per year) in all 10 time periods (beta = -26.3 to beta = -36.7; P = 0.0039 to P < 0.0001). The stratified analysis showed that this inverse relation was significant only in countries with above median level of smoking (>2437 cigarettes/adult/year) or animal fat minus fish fat consumption (22.4% E). An increase in fish consumption by 1% E was calculated to reduce mean male LCM rate of the populations examined in the age class of 45-74 years by 8.4%. In women, no significant relation between fish consumption and LCM could be established. Fish consumption is associated with a reduced risk from LCM, but this possible protective effect is clear-cut only in men and in countries with high levels of cigarette smoking or animal fat consumption.

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.

Occurrence, size, and tag retention of sneaker male hatchery rainbow trout

USGS Publications Warehouse

Isely, J.J.; Grabowski, T.B.

2004-01-01

One alternative reproductive tactic involving early-maturing, cryptic males is referred to as "sneaking." Although sneakers tend to be easily detectable upon close inspection, little is known about the proportion of a fish population consisting of sneakers. We examined 15,400 age-1 rainbow trout Oncorhynchus mykiss in a hatchery. Total length (mm), wet weight (g), and sex (sneaker male or unknown) were recorded for each fish. We also individually tagged each sneaker male with soft visual implant alphanumeric (VIalpha) tags that were sequentially numbered and held the fish for 25 d before inspection. Sneakers constituted 2.8% of the hatchery rainbow trout population and were smaller in total length and weight than typical rainbow trout of the same age. Retention of the VIalpha tags in sneakers was 58.9%, significantly lower than has been reported under similar circumstances. We found that sneaker males may contribute substantially to hatchery populations. Reduced tag retention in sneakers may bias studies evaluating the effect of hatchery fish on wild populations. We believe that hatchery-produced sneaker males have the potential to contribute importantly to the genetic composition of wild populations.

Aggressiveness overcomes body-size effects in fights staged between invasive and native fish species with overlapping niches.

PubMed

Sanches, Fábio Henrique Carretero; Miyai, Caio Akira; Costa, Tânia Márcia; Christofoletti, Ronaldo Adriano; Volpato, Gilson Luiz; Barreto, Rodrigo Egydio

2012-01-01

Approximately 50 years ago, Nile tilapia were accidentally introduced to Brazil, and the decline of pearl cichlid populations, which has been intensified by habitat degradation, in some locations has been associated with the presence of Nile tilapia. There is, however, little strong empirical evidence for the negative interaction of non-native fish populations with native fish populations; such evidence would indicate a potential behavioural mechanism that could cause the population of the native fish to decline. In this study, we show that in fights staged between pairs of Nile tilapia and pearl cichlids of differing body size, the Nile tilapia were more aggressive than the pearl cichlid. Because this effect prevailed over body-size effects, the pearl cichlids were at a disadvantage. The niche overlap between the Nile tilapia and the pearl cichlid in nature, and the competitive advantage shown by the Nile tilapia in this study potentially represent one of several possible results of the negative interactions imposed by an invasive species. These negative effects may reduce population viability of the native species and cause competitive exclusion.

Extirpation and recolonization in a metapopulation of an endangered fish, the tidewater goby

USGS Publications Warehouse

Lafferty, K.D.; Swift, C.C.; Ambrose, R.F.

1999-01-01

The tidewater goby (Eucyclogobius newberryi), an endangered species in the United States, occurs in a series of isolated coastal wetlands in California. Using historical presence-absence data and our own surveys, we estimated annual rates of extirpation and recolonization for several populations of the goby in southern California. As predicted, large wetlands had lower rates of extirpation than small wetlands. There was a negative but statistically nonsignificant correlation between recolonization rate and distance to the nearest northerly source population. Populations at small sites were sensitive to drought, presumably because droughts can eliminate suitable habitat at small wetlands. Populations in small wetlands have declined over time, even after accounting for variation in stream flow, supporting the species' endangered status. Our study emphasizes the need to understand metapopulation dynamics for conserving species where the unit of conservation is a local population. It is also emphasizes the importance of not treating metapopulations as identical units. Finally, our results provide a means for describing the decline of a species that is complex in time and space and provide insight into how to target protection measures among metapopulations.

TITAN: inference of copy number architectures in clonal cell populations from tumor whole-genome sequence data

PubMed Central

Roth, Andrew; Khattra, Jaswinder; Ho, Julie; Yap, Damian; Prentice, Leah M.; Melnyk, Nataliya; McPherson, Andrew; Bashashati, Ali; Laks, Emma; Biele, Justina; Ding, Jiarui; Le, Alan; Rosner, Jamie; Shumansky, Karey; Marra, Marco A.; Gilks, C. Blake; Huntsman, David G.; McAlpine, Jessica N.; Aparicio, Samuel

2014-01-01

The evolution of cancer genomes within a single tumor creates mixed cell populations with divergent somatic mutational landscapes. Inference of tumor subpopulations has been disproportionately focused on the assessment of somatic point mutations, whereas computational methods targeting evolutionary dynamics of copy number alterations (CNA) and loss of heterozygosity (LOH) in whole-genome sequencing data remain underdeveloped. We present a novel probabilistic model, TITAN, to infer CNA and LOH events while accounting for mixtures of cell populations, thereby estimating the proportion of cells harboring each event. We evaluate TITAN on idealized mixtures, simulating clonal populations from whole-genome sequences taken from genomically heterogeneous ovarian tumor sites collected from the same patient. In addition, we show in 23 whole genomes of breast tumors that the inference of CNA and LOH using TITAN critically informs population structure and the nature of the evolving cancer genome. Finally, we experimentally validated subclonal predictions using fluorescence in situ hybridization (FISH) and single-cell sequencing from an ovarian cancer patient sample, thereby recapitulating the key modeling assumptions of TITAN. PMID:25060187

Minority group participation in recreational fishing: the role of demographics and constraints

Treesearch

Kelly L. Finn; David K. Loomis

1998-01-01

Minority populations are increasing in numbers and will influence participation and expenditures in fishing activities. This, in turn, will affect fisheries management. Between 1995 and 2025, 78% of the net change in the U.S. population will be attributed to minority group members. This increase in minority populations will be related to a potential increase in the...

Genetic diversity and population structure of bocachico Prochilodus magdalenae (Pisces, Prochilodontidae) in the Magdalena River basin and its tributaries, Colombia

PubMed Central

Berdugo, Gilberto Orozco; Narváez Barandica, Juan C.

2014-01-01

Prochilodus magdalenae is an endemic freshwater fish that occurs in the Magdalena, Sinú and Atrato hydrographic basins. It has an important economic role and is a food resource for the artisanal fishing communities. Its socioeconomic importance contrasts with the current status of its fisheries, where stocks are being depleted. Considering its importance and lack of information on its genetic structure, we used seven microsatellite markers to assess the genetic structure of wild populations of P. magdalenae. The genetic diversity was assessed and the population genetic structure was estimated through Fst, analysis of molecular variance and Bayesian analysis. A total of 290 alleles were found in all loci throughout all population. The high polymorphism contrasts with the levels of observed heterozygosity (Ho = 0.276), which are the lowest values recorded for the family. We found three populations of bocachico coexisting throughout the studied system, contradicting the hypothesis that freshwater migratory fish form panmictic populations. These results on the genetic structure of P. magdalenae constitute tools for a better understanding of the behavior and biology of this species, contributing to fish management and conservation programs. PMID:24688289

78 FR 17350 - Certain Frozen Fish Fillets From the Socialist Republic of Vietnam: Final Results of Antidumping...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-21

...The Department of Commerce (``the Department'') published the Preliminary Results of the eighth administrative review and aligned new shipper reviews on certain frozen fish fillets from the Socialist Republic of Vietnam (``Vietnam'') on September 12, 2012.\\1\\ We gave interested parties an opportunity to comment on the Preliminary Results. Based upon our analysis of the comments and information received, we made changes to the margin calculations for these final results. The final dumping margins are listed below in the ``Final Results of the Administrative Reviews'' section of this notice. The period of review (``POR'') is August 1, 2010, through July 31, 2011. ---------------------------------------------------------------------------

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.

Habitual fish consumption does not prevent a decrease in LCPUFA status in pregnant women (the Seychelles Child Development Nutrition Study)

PubMed Central

Bonham, M.P.; Duffy, E.M.; Wallace, J.M.W.; Robson, P.J.; Myers, G.J; Davidson, P.W.; Clarkson, T.W.; Shamlaye, C.F; Strain., J.J.

2008-01-01

SUMMARY Information on the status of long chain polyunsaturated fatty acids (LC-PUFA) in pregnancy and breast milk in very high fish eating populations is limited. The aim of this study was to examine dietary intake and changes in fatty acid status in a population of pregnant women in the Republic of Seychelles. Serum docosahexaenoic acid (DHA) decreased significantly between 28 weeks gestation and delivery (n=196). DHA status did not correlate significantly with length of gestation and was not associated with self reported fish intake which was high at 527 g/wk. In breast milk, the ratio of DHA to arachidonic acid (AA) was consistent with those observed in other high fish eating populations. Overall the data suggest that high exposure to LCPUFAs from habitual fish consumption does not prevent the documented decrease in LCPUFA status in pregnancy that occurs as a result of fetal accretion in the third trimester of pregnancy. PMID:18585023

Habitual fish consumption does not prevent a decrease in LCPUFA status in pregnant women (the Seychelles Child Development Nutrition Study).

PubMed

Bonham, M P; Duffy, E M; Wallace, J M W; Robson, P J; Myers, G J; Davidson, P W; Clarkson, T W; Shamlaye, C F; Strain, J J

2008-06-01

Information on the status of long-chain polyunsaturated fatty acids (LCPUFAs) in pregnancy and breast milk in very high fish-eating populations is limited. The aim of this study was to examine dietary intake and changes in fatty acid status in a population of pregnant women in the Republic of Seychelles. Serum docosahexaenoic acid (DHA) decreased significantly between 28-week gestation and delivery (n=196). DHA status did not correlate significantly with length of gestation and was not associated with self-reported fish intake, which was high at 527 g/week. In breast milk, the ratio of DHA to arachidonic acid (AA) was consistent with those observed in other high fish-eating populations. Overall the data suggest that high exposure to LCPUFAs from habitual fish consumption does not prevent the documented decrease in LCPUFA status in pregnancy that occurs as a result of foetal accretion in the third trimester of pregnancy.

Developing recreational harvest regulations for an unexploited lake trout population

USGS Publications Warehouse

Lenker, Melissa A; Weidel, Brian C.; Jensen, Olaf P.; Solomon, Christopher T.

2016-01-01

Developing fishing regulations for previously unexploited populations presents numerous challenges, many of which stem from a scarcity of baseline information about abundance, population productivity, and expected angling pressure. We used simulation models to test the effect of six management strategies (catch and release; trophy, minimum, and maximum length limits; and protected and exploited slot length limits) on an unexploited population of Lake Trout Salvelinus namaycush in Follensby Pond, a 393-ha lake located in New York State’s Adirondack Park. We combined field and literature data and mark–recapture abundance estimates to parameterize an age-structured population model and used the model to assess the effects of each management strategy on abundance, catch per unit effort (CPUE), and harvest over a range of angler effort (0–2,000 angler-days/year). Lake Trout density (3.5 fish/ha for fish ≥ age 13, the estimated age at maturity) was similar to densities observed in other unexploited systems, but growth rate was relatively slow. Maximum harvest occurred at levels of effort ≤ 1,000 angler-days/year in all the scenarios considered. Regulations that permitted harvest of large postmaturation fish, such as New York’s standard Lake Trout minimum size limit or a trophy size limit, resulted in low harvest and high angler CPUE. Regulations that permitted harvest of small and sometimes immature fish, such as a protected slot or maximum size limit, allowed high harvest but resulted in low angler CPUE and produced rapid declines in harvest with increases in effort beyond the effort consistent with maximum yield. Management agencies can use these results to match regulations to management goals and to assess the risks of different management options for unexploited Lake Trout populations and other fish species with similar life history traits.

A conservation plan for native fishes of the Lower Colorado River

USGS Publications Warehouse

Minckley, W.L.; Marsh, P.C.; Deacon, J.E.; Dowling, T.E.; Hedrick, P.W.; Matthews, W.J.; Mueller, G.

2003-01-01

The native fish fauna of the lower Colorado River, in the western United States, includes four “big-river” fishes that are federally listed as endangered. Existing recovery implementation plans are inadequate for these critically imperiled species. We describe a realistic, proactive management program founded on demographic and genetic principles and crafted to avoid potential conflicts with nonnative sport fisheries. In this program, native species would breed and their progeny grow in isolated, protected, off-channel habitats in the absence of nonnative fishes. Panmictic adult populations would reside in the main channel and connected waters, exchanging reproductive adults and repatriated subadults with populations occupying isolated habitats. Implementation of the plan would greatly enhance recovery potential of the four listed fishes.

Simulating the Tragedy of the Commons with the Fishing Game

NASA Astrophysics Data System (ADS)

Prothero, W. A.

2009-12-01

The "Tragedy of the Commons" (Garrett Hardin) exemplifies the challenges and conflicts that occur when a common resource is shared by multiple users whose motive is profit. The global fisheries provide a timely example of the over-exploitation of a shared resource. The "Fishing Game" was inspired by the "Fishbanks Game" of Dennis Meadows. The student plays against two virtual fishing companies in an effort to make as much money as possible, while exploring the management issues that arise when trying to sustain the fish population for future profits. The game is played with four realistic management scenarios. These are 1) free for all, 2) limited fishing season, 3) marine reserves, and 4) catch shares. For each scenario the student makes decisions about how many ships to build and how many to send to each of two fishing areas. A simple population model works in the background to determine the catch and number of new fish that are added to the population through birth each year. The student sets the management parameters for each of the scenarios. Each of the scenarios can be modeled by the student to determine the optimum parameters. The player will quickly find that a single aggressive player whose profit motive trumps concern over the sustainability of the population will almost always win under all scenarios except the 4’th. When the season is limited, everybody fishes harder. With marine reserves, catches will drop, but the population will not disappear completely. Only catch shares sustain the population while providing reasonable long term profit for the fishing companies. For each management scenario, the player is asked a pre and a post thought question asking what issues they think are relevant. After all scenarios are played, the student can edit the post versions of the thought questions, plus several added questions about their experience with the game. The game results and answers to the questions are then automatically emailed to the instructor, or printed for hand-in. The game provides an effective way to start students thinking about how science and policy intersect and how human nature and the profit motive affect management strategies. Important issues that are not addressed by the game are destruction of fisheries habitat, by-catch, and international law.

Toxic hydrogen sulfide and dark caves: phenotypic and genetic divergence across two abiotic environmental gradients in Poecilia mexicana.

PubMed

Tobler, Michael; Dewitt, Thomas J; Schlupp, Ingo; García de León, Francisco J; Herrmann, Roger; Feulner, Philine G D; Tiedemann, Ralph; Plath, Martin

2008-10-01

Divergent natural selection drives evolutionary diversification. It creates phenotypic diversity by favoring developmental plasticity within populations or genetic differentiation and local adaptation among populations. We investigated phenotypic and genetic divergence in the livebearing fish Poecilia mexicana along two abiotic environmental gradients. These fish typically inhabit nonsulfidic surface rivers, but also colonized sulfidic and cave habitats. We assessed phenotypic variation among a factorial combination of habitat types using geometric and traditional morphometrics, and genetic divergence using quantitative and molecular genetic analyses. Fish in caves (sulfidic or not) exhibited reduced eyes and slender bodies. Fish from sulfidic habitats (surface or cave) exhibited larger heads and longer gill filaments. Common-garden rearing suggested that these morphological differences are partly heritable. Population genetic analyses using microsatellites as well as cytochrome b gene sequences indicate high population differentiation over small spatial scale and very low rates of gene flow, especially among different habitat types. This suggests that divergent environmental conditions constitute barriers to gene flow. Strong molecular divergence over short distances as well as phenotypic and quantitative genetic divergence across habitats in directions classic to fish ecomorphology suggest that divergent selection is structuring phenotypic variation in this system.

The Mangrove Nursery Paradigm Revisited: Otolith Stable Isotopes Support Nursery-to-Reef Movements by Indo-Pacific Fishes

PubMed Central

Kimirei, Ismael A.; Nagelkerken, Ivan; Mgaya, Yunus D.; Huijbers, Chantal M.

2013-01-01

Mangroves and seagrass beds have long been perceived as important nurseries for many fish species. While there is growing evidence from the Western Atlantic that mangrove habitats are intricately connected to coral reefs through ontogenetic fish migrations, there is an ongoing debate of the value of these coastal ecosystems in the Indo-Pacific. The present study used natural tags, viz. otolith stable carbon and oxygen isotopes, to investigate for the first time the degree to which multiple tropical juvenile habitats subsidize coral reef fish populations in the Indo Pacific (Tanzania). Otoliths of three reef fish species (Lethrinus harak, L. lentjan and Lutjanus fulviflamma) were collected in mangrove, seagrass and coral reef habitats and analyzed for stable isotope ratios in the juvenile and adult otolith zones. δ13C signatures were significantly depleted in the juvenile compared to the adult zones, indicative of different habitat use through ontogeny. Maximum likelihood analysis identified that 82% of adult reef L. harak had resided in either mangrove (29%) or seagrass (53%) or reef (18%) habitats as juveniles. Of adult L. fulviflamma caught from offshore reefs, 99% had passed through mangroves habitats as juveniles. In contrast, L. lentjan adults originated predominantly from coral reefs (65–72%) as opposed to inshore vegetated habitats (28–35%). This study presents conclusive evidence for a nursery role of Indo-Pacific mangrove habitats for reef fish populations. It shows that intertidal habitats that are only temporarily available can form an important juvenile habitat for some species, and that reef fish populations are often replenished by multiple coastal habitats. Maintaining connectivity between inshore vegetated habitats and coral reefs, and conserving habitat mosaics rather than single nursery habitats, is a major priority for the sustainability of various Indo Pacific fish populations. PMID:23776658

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.

The mangrove nursery paradigm revisited: otolith stable isotopes support nursery-to-reef movements by Indo-Pacific fishes.

PubMed

Kimirei, Ismael A; Nagelkerken, Ivan; Mgaya, Yunus D; Huijbers, Chantal M

2013-01-01

Mangroves and seagrass beds have long been perceived as important nurseries for many fish species. While there is growing evidence from the Western Atlantic that mangrove habitats are intricately connected to coral reefs through ontogenetic fish migrations, there is an ongoing debate of the value of these coastal ecosystems in the Indo-Pacific. The present study used natural tags, viz. otolith stable carbon and oxygen isotopes, to investigate for the first time the degree to which multiple tropical juvenile habitats subsidize coral reef fish populations in the Indo Pacific (Tanzania). Otoliths of three reef fish species (Lethrinus harak, L. lentjan and Lutjanus fulviflamma) were collected in mangrove, seagrass and coral reef habitats and analyzed for stable isotope ratios in the juvenile and adult otolith zones. δ(13)C signatures were significantly depleted in the juvenile compared to the adult zones, indicative of different habitat use through ontogeny. Maximum likelihood analysis identified that 82% of adult reef L. harak had resided in either mangrove (29%) or seagrass (53%) or reef (18%) habitats as juveniles. Of adult L. fulviflamma caught from offshore reefs, 99% had passed through mangroves habitats as juveniles. In contrast, L. lentjan adults originated predominantly from coral reefs (65-72%) as opposed to inshore vegetated habitats (28-35%). This study presents conclusive evidence for a nursery role of Indo-Pacific mangrove habitats for reef fish populations. It shows that intertidal habitats that are only temporarily available can form an important juvenile habitat for some species, and that reef fish populations are often replenished by multiple coastal habitats. Maintaining connectivity between inshore vegetated habitats and coral reefs, and conserving habitat mosaics rather than single nursery habitats, is a major priority for the sustainability of various Indo Pacific fish populations.

Establishment of a fish community in the hayden-rhodes and salt-gila aqueducts, Arizona

USGS Publications Warehouse

Mueller, G.

1996-01-01

Fish populations were studied in the Central Arizona Project's canal system during the first 4 years of aqueduct operation (1986-1989). Ichthyoplankton entering the canal from Lake Havasu averaged 1 larva/m3 during April-June 1987 and 1988. Larval fish densities increased significantly in downstream samples, substantiating diver observations that fish were spawning in the canal system. Of the 16 fish species collected, 14 were assumed to have originated from Lake Havasu and 2 were introduced by anglers from their bait buckets. Initially, the fish community was dominated numerically by threadfin shad Dorosoma petenense (>88%), centrarchids (< 10%), cyprinids (<2%), and striped bass Morone saxatilis (<1%). However, as annual water diversions increased from 13 x 108 m3 in 1986 to 9.4 x 108 m3 in 1989, community composition shifted from clupeids to centrarchids (70%). Fish densities dropped from an estimated 1,260 fish/ha in 1986 to 17 fish/ha in 1989, and biomass dropped from 116 to 73 kg/ha. Declines were attributed to higher operational velocities, associated scour, deprivation, and predation. Although initial populations adjusted downward to planned operational conditions, the fish community continued to represent a potentially valuable, but as yet unused, resource.

Mangroves enhance the biomass of coral reef fish communities in the Caribbean.

PubMed

Mumby, Peter J; Edwards, Alasdair J; Arias-González, J Ernesto; Lindeman, Kenyon C; Blackwell, Paul G; Gall, Angela; Gorczynska, Malgosia I; Harborne, Alastair R; Pescod, Claire L; Renken, Henk; Wabnitz, Colette C C; Llewellyn, Ghislane

2004-02-05

Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs.

Mangroves enhance the biomass of coral reef fish communities in the Caribbean

NASA Astrophysics Data System (ADS)

Mumby, Peter J.; Edwards, Alasdair J.; Ernesto Arias-González, J.; Lindeman, Kenyon C.; Blackwell, Paul G.; Gall, Angela; Gorczynska, Malgosia I.; Harborne, Alastair R.; Pescod, Claire L.; Renken, Henk; C. C. Wabnitz, Colette; Llewellyn, Ghislane

2004-02-01

Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs.

Turnover and accumulation of genetic diversity across large time-scale cycles of isolation and connection of populations

PubMed Central

Alcala, Nicolas; Vuilleumier, Séverine

2014-01-01

Major climatic and geological events but also population history (secondary contacts) have generated cycles of population isolation and connection of long and short periods. Recent empirical and theoretical studies suggest that fast evolutionary processes might be triggered by such events, as commonly illustrated in ecology by the adaptive radiation of cichlid fishes (isolation and reconnection of lakes and watersheds) and in epidemiology by the fast adaptation of the influenza virus (isolation and reconnection in hosts). We test whether cyclic population isolation and connection provide the raw material (standing genetic variation) for species evolution and diversification. Our analytical results demonstrate that population isolation and connection can provide, to populations, a high excess of genetic diversity compared with what is expected at equilibrium. This excess is either cyclic (high allele turnover) or cumulates with time depending on the duration of the isolation and the connection periods and the mutation rate. We show that diversification rates of animal clades are associated with specific periods of climatic cycles in the Quaternary. We finally discuss the importance of our results for macroevolutionary patterns and for the inference of population history from genomic data. PMID:25253456

Observations of the distributions of five fish species in a small Appalachian stream

USGS Publications Warehouse

Larson, Gary L.; Hoffman, Robert L.; Moore, S.E.

2002-01-01

The notion has been growing that resident stream fishes exhibit a greater capacity for movement than was previously thought. In this study, we recorded the distributions of four resident fish species (longnose dace Rhinichthys cataractae, blacknose dace R. atratulus, mottled sculpin Cottus bairdi, and rainbow trout Oncorhynchus mykiss) and one nonresident species (central stoneroller Campostoma anomalum) in Rock Creek, a small tributary of Cosby Creek in Great Smoky Mountains National Park, over the period 1979a??1995. During this study, 1,998 individuals of resident species were collected from stream sections considered to be within a common area of distribution for each species. Forty-five individuals of resident and nonresident species were captured upstream of these areas, and eight of these fish were considered to be larger than individuals considered typical for each species. Small mammal dispersal theory concepts were used to classify and describe fish movements outside of common areas of distribution. These movements were identified as important in maintaining population connectivity within stream drainages, contributing to reducing the potential for local extinctions of populations and to the recolonization of unoccupied habitats. This study highlights the need for continued study of fish movements in stream drainages and for development of appropriate resource management strategies based partly on the spatial dynamics of fish populations and communities.

Mammalian metabolic rates in the hottest fish on earth.

PubMed

Wood, Chris M; Brix, Kevin V; De Boeck, Gudrun; Bergman, Harold L; Bianchini, Adalto; Bianchini, Lucas F; Maina, John N; Johannsson, Ora E; Kavembe, Geraldine D; Papah, Michael B; Letura, Kisipan M; Ojoo, Rodi O

2016-06-03

The Magadi tilapia, Alcolapia grahami, a small cichlid fish of Lake Magadi, Kenya lives in one of the most challenging aquatic environments on earth, characterized by very high alkalinity, unusual water chemistry, and extreme O2, ROS, and temperature regimes. In contrast to most fishes which live at temperatures substantially lower than the 36-40 °C of mammals and birds, an isolated population (South West Hot Springs, SWHS) of Magadi tilapia thrives in fast-flowing hotsprings with daytime highs of 43 °C and night-time lows of 32 °C. Another population (Fish Springs Lagoon, FSL) lives in a lagoon with fairly stable daily temperatures (33-36 °C). The upper critical temperatures (Ctmax) of both populations are very high; moreover the SWHS tilapia exhibit the highest Ctmax (45.6 °C) ever recorded for a fish. Routine rates of O2 consumption (MO2) measured on site, together with MO2 and swimming performance at 25, 32, and 39 °C in the laboratory, showed that the SWHS tilapia exhibited the greatest metabolic performance ever recorded in a fish. These rates were in the basal range of a small mammal of comparable size, and were all far higher than in the FSL fish. The SWHS tilapia represents a bellwether organism for global warming.

How long can fisheries management delay action in response to ecosystem and climate change?

PubMed

Brown, Christopher J; Fulton, Elizabeth A; Possingham, Hugh P; Richardson, Anthony J

2012-01-01

Sustainable management of fisheries is often compromised by management delaying implementation of regulations that reduce harvest, in order to maintain higher catches in the short-term. Decreases or increases in fish population growth rate driven by environmental change, including ecosystem and climate change, affect the harvest that can be taken sustainably. If not acted on rapidly, environmental change could result in unsustainable fishing or missed opportunity for higher catches. Using simulation models of harvested fish populations influenced by environmental change, we explore how long fisheries managers can afford to wait before changing harvest regulations in response to changes in population growth. If environmental change causes population declines, delays greater than five years increase the probability of population collapse. Species with fast and highly variable population growth rates are more susceptible to collapse under delays and should be a priority for revised management where delays occur. Generally, the long-term cost of delay, in terms of lost fishing opportunity, exceeds the short-term benefits of overfishing. Lowering harvest limits and monitoring for environmental change can alleviate the impact of delays; however, these measures may be more costly than reducing delays. We recommend that management systems that allow rapid responses to population growth changes be enacted for fisheries management to adapt to ecosystem and climate change.

78 FR 59269 - Endangered and Threatened Wildlife and Plants; Endangered Species Status for the Fluted...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-26

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R4-ES-2012... for the Fluted Kidneyshell and Slabside Pearlymussel AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine endangered...

Population Viability Analysis of Riverine Fishes

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

Bates, P.; Chandler, J.; Jager, H.I.

Many utilities face conflkts between two goals: cost-efficient hydropower generation and protecting riverine fishes. Research to develop ecological simulation tools that can evaluate alternative mitigation strategies in terms of their benefits to fish populations is vital to informed decision-making. In this paper, we describe our approach to population viability analysis of riverine fishes in general and Snake River white sturgeon in particular. We are finding that the individual-based modeling approach used in previous in-stream flow applications is well suited to addressing questions about the viability of species of concern for several reasons. Chief among these are: (1) the abiIity tomore » represent the effects of individual variation in life history characteristics on predicted population viabili~, (2) the flexibili~ needed to quanti~ the ecological benefits of alternative flow management options by representing spatial and temporal variation in flow and temperaturty and (3) the flexibility needed to quantifi the ecological benefits of non-flow related manipulations (i.e., passage, screening and hatchery supplementation).« less

Are we going about chemical risk assessment for the aquatic environment the wrong way?

PubMed

Johnson, Andrew C; Sumpter, John P

2016-07-01

The goal of protecting the aquatic environment through testing thousands of chemicals against hundreds of aquatic species with thousands of endpoints while also considering mixtures is impossible given the present resources. Much of the impetus for studies on micropollutants, such as pharmaceuticals, came from the topic of endocrine disruption in wild fish. But despite concern over reductions in fish fertility, there is little evidence that fish populations are in peril. Indeed, fish biologists suggest that many cyprinid populations have been recovering for the past 30 to 40 yr. The central assumption, key to current risk assessment, that effects observed in the laboratory or predicted by models are readily transferrable to the population level, is therefore questionable. The neglect in monitoring wildlife populations is the key weakness in environmental protection strategies. If we do not know whether aquatic wildlife species are declining or increasing, how valuable are our other ecotoxicological activities? Environ Toxicol Chem 2016;35:1609-1616. © 2016 SETAC. © 2016 SETAC.

Dietary soy, meat, and fish proteins modulate the effects of prebiotic raffinose on composition and fermentation of gut microbiota in rats.

PubMed

Bai, Gaowa; Tsuruta, Takeshi; Nishino, Naoki

2018-06-01

Soy, meat (mixture of pork and beef), and fish proteins were fed to rats with and without prebiotic raffinose (RAF), and the composition and fermentation of gut microbiota were examined. Bifidobacterium spp. populations were higher, and propionic acid concentration was lower in soy protein-fed than meat protein-fed rats. Likewise, Enterobacteriaceae populations were higher in fish protein-fed rats than other rats. RAF feeding increased Bifidobacterium spp. and decreased Faecalibacterium prausnitzii populations regardless of the dietary protein source. Interactions between dietary proteins and RAF were shown for Lactobacillus spp. and Clostridium perfringens group; the increase of Lactobacillus spp. populations by RAF was seen only for soy protein-fed rats, whereas the reduction of C. perfringens group by RAF was evident in fish and meat protein-fed rats. It is concluded that dietary proteins may differentially modulate the effects of prebiotic oligosaccharides on gut fermentation and microbiota, with differences observed between plant and animal proteins.

Comparing the Reproductive Success of Yakima River Hatchery- and Wild-Origin Spring Chinook; Yakima/Klickitat Fisheries Project Monitoring and Evaluation, 2004-2005 Annual Report.

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

Schroder, S.L.; Pearsons, T.N.; Knudsen, C.M.

2005-05-01

A growing body of literature suggests that adult salmon produced by artificial culture are not as reproductively successful as wild fish when they spawn under natural conditions. Behavioral, morphological, and physiological divergences have been observed between hatchery and wild fish. These disparities are the likely proximate causes of the differences seen in the reproductive success of hatchery and wild salmonids. Two evolutionary paradigms have been proposed to explain why salmonids cultured in hatcheries are genetically and phenotypically different from wild cohorts. The first proposes that natural selection has been significantly relaxed in hatcheries. Consequently, fish that normally would have perishedmore » because of the possession of unsuitable traits are able to survive. If these traits have a genetic basis, they may become established in a hatchery population and cause its productivity to be less than expected if the fish are once again exposed to natural selection pressures. The second theorizes that environmental and social conditions in hatcheries are less variable than in the natural environment and that these conditions will remain relatively constant from one generation to the next. In this circumstance, selection for genetic traits that adapt fish to artificial culture will become prevalent in the population. Such traits may be mal-adaptive under natural conditions. Many of the studies that have compared the reproductive success (RS) of hatchery and wild fish, however, have used non-local hatchery fish that have experienced multiple generations of hatchery culture. Few efforts have been made where both the hatchery and wild fish have originated from the same population. When such studies have been performed differences in the competency of the fish to produce offspring have not been detected or are not as great as those expressed when non-local hatchery fish have been used. The hatchery spring Chinook produced by the Yakima Fisheries Project originated from wild fish returning to the upper Yakima River. When they return as adults, almost all of them will spawn naturally in the Yakima River. The offspring they produce are expected to augment the Yakima spring Chinook population. Whether such an increase will occur or how great it may be depends on two factors, the ability of hatchery fish to reproduce under natural conditions and the capacity of their offspring to survive to maturity. One of the objectives of the Yakima Fisheries Project is to determine whether the hatchery-origin adults produced by the project have experienced any reduction in their ability to reproduce under natural conditions. To accomplish that objective an observation stream was built in 2000 on the grounds of the Cle Elum Supplementation and Research Facility. Beginning in 2001 hatchery and wild spring Chinook from the upper Yakima River stock have been introduced into the stream and allowed to reproduce. Microsatellite DNA is used to establish the genetic relationships between the adults placed into the stream and fry that are produced by each population. Six populations consisting of mixtures of wild and hatchery fish have been placed into the stream. Pedigree assessments have been completed on five of them. These assessments have shown that the reproductive success in males is often twice as variable as that experienced by females. In the five populations so far examined; wild males (age 4 and 5) produced the most offspring. The success of comparable hatchery males relative to wild males ranged from 37% to 113%. Hatchery and wild males maturing as 3-yr-olds (jacks) and as 1- and 0-yr-olds (precocious males) were also used in the study populations. They were not as successful at producing offspring as the larger hatchery and wild males. During 2001 and 2002 two populations of hatchery and wild fish were placed into the observation stream each year. Each one occupied about half of the structure. In these populations wild females exhibited a superior capacity to deposit eggs. In addition, their eggs survived to the fry stage at higher rates. This survival advantage ranged from 1.9 to 11.7%. In 2003 the entire observation stream was made available to a single population of fish in an effort to reduce intrasexual competition among the females for redd locations. In this year, hatchery females were better at depositing eggs (12.5%) and their buried eggs also achieved a higher egg-to-fry survival rate (3.4%). This suggests that at low population levels hatchery females were as competent as wild fish in burying eggs and in producing fry. Although variation in the reproductive success of females was lower than that seen in males it could be quite variable. For example, coefficient of variation values calculated on female RS ranged from 34 to 77% in the populations we examined. Numerous factors may affect RS in females.« less

Extreme Genetic Structure in a Small-Bodied Freshwater Fish, the Purple Spotted Gudgeon, Mogurnda adspersa (Eleotridae)

PubMed Central

Hughes, Jane M.; Real, Kathryn M.; Marshall, Jonathan C.; Schmidt, Daniel J.

2012-01-01

Freshwater fish are a group that is especially susceptible to biodiversity loss as they often exist naturally in small, fragmented populations that are vulnerable to habitat degradation, pollution and introduction of exotic species. Relatively little is known about spatial dynamics of unperturbed populations of small-bodied freshwater fish species. This study examined population genetic structure of the purple spotted gudgeon (Mogurnda adspersa, Eleotridae), a small-bodied freshwater fish that is widely distributed in eastern Australia. The species is threatened in parts of its range but is common in coastal streams of central Queensland where this study took place. Microsatellite (msat) and mitochondrial DNA (mtDNA) variation was assessed for nine sites from four stream sections in two drainage basins. Very high levels of among population structure were observed (msat F ST = 0.18; mtDNA ΦST = 0.85) and evidence for contemporary migration among populations was rare and limited to sites within the same section of stream. Hierarchical structuring of variation was best explained by stream section rather than by drainage basin. Estimates of contemporary effective population size for each site was low (range 28 – 63, Sibship method), but compared favorably with similar estimates for other freshwater fish species, and there was no genetic evidence for inbreeding or recent population bottlenecks. In conclusion, within a stable part of its range, M adspersa exists as a series of small, demographically stable populations that are highly isolated from one another. Complimentary patterns in microsatellites and mtDNA indicate this structuring is the result of long-term processes that have developed over a remarkably small spatial scale. High population structure and limited dispersal mean that recolonisation of locally extinct populations is only likely to occur from closely situated populations within stream sections. Limited potential for recolonisation should be considered as an important factor in conservation and management of this species. PMID:22808190

The Principles of Buoyancy in Marine Fish Eggs and Their Vertical Distributions across the World Oceans.

PubMed

Sundby, Svein; Kristiansen, Trond

2015-01-01

Buoyancy acting on plankton, i.e. the difference in specific gravity between plankton and the ambient water, is a function of salinity and temperature. From specific gravity measurements of marine fish eggs salinity appears to be the only determinant of the buoyancy indicating that the thermal expansions of the fish egg and the ambient seawater are equal. We analyze the mechanisms behind thermal expansion in fish eggs in order to determine to what extent it can be justified to neglect the effects of temperature on buoyancy. Our results confirm the earlier assumptions that salinity is the basic determinant on buoyancy in marine fish eggs that, in turn, influence the vertical distributions and, consequently, the dispersal of fish eggs from the spawning areas. Fish populations have adapted accordingly by producing egg specific gravities that tune the egg buoyancy to create specific vertical distributions for each local population. A wide variety of buoyancy adaptations are found among fish populations. The ambient physical conditions at the spawning sites form a basic constraint for adaptation. In coastal regions where salinity increases with depth, and where the major fraction of the fish stocks spawns, pelagic and mesopelagic egg distributions dominate. However, in the larger part of worlds' oceans salinity decreases with depth resulting in different egg distributions. Here, the principles of vertical distributions of fish eggs in the world oceans are presented in an overarching framework presenting the basic differences between regions, mainly coastal, where salinity increases with depth and the major part of the world oceans where salinity decreases with depth. We show that under these latter conditions, steady-state vertical distribution of mesopelagic fish eggs cannot exist as it does in most coastal regions. In fact, a critical spawning depth must exist where spawning below this depth threshold results in eggs sinking out of the water column and become lost for recruitment to the population. An example of adaptation to such conditions is Cape hake spawning above the critical layer in the Northern Benguela upwelling ecosystem. The eggs rise slowly in the onshore subsurface current below the Ekman layer, hence being advected inshore where the hatched larvae concentrate with optimal feeding conditions.

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 this river. These studies will also help to develop blood tests as reliable health indicators in wild fish populations. Copyright © 2017 Elsevier Inc. All rights reserved.

Models projecting the fate of fish populations under climate change need to be based on valid physiological mechanisms.

PubMed

Lefevre, Sjannie; McKenzie, David J; Nilsson, Göran E

2017-09-01

Some recent modelling papers projecting smaller fish sizes and catches in a warmer future are based on erroneous assumptions regarding (i) the scaling of gills with body mass and (ii) the energetic cost of 'maintenance'. Assumption (i) posits that insurmountable geometric constraints prevent respiratory surface areas from growing as fast as body volume. It is argued that these constraints explain allometric scaling of energy metabolism, whereby larger fishes have relatively lower mass-specific metabolic rates. Assumption (ii) concludes that when fishes reach a certain size, basal oxygen demands will not be met, because of assumption (i). We here demonstrate unequivocally, by applying accepted physiological principles with reference to the existing literature, that these assumptions are not valid. Gills are folded surfaces, where the scaling of surface area to volume is not constrained by spherical geometry. The gill surface area can, in fact, increase linearly in proportion to gill volume and body mass. We cite the large body of evidence demonstrating that respiratory surface areas in fishes reflect metabolic needs, not vice versa, which explains the large interspecific variation in scaling of gill surface areas. Finally, we point out that future studies basing their predictions on models should incorporate factors for scaling of metabolic rate and for temperature effects on metabolism, which agree with measured values, and should account for interspecific variation in scaling and temperature effects. It is possible that some fishes will become smaller in the future, but to make reliable predictions the underlying mechanisms need to be identified and sought elsewhere than in geometric constraints on gill surface area. Furthermore, to ensure that useful information is conveyed to the public and policymakers about the possible effects of climate change, it is necessary to improve communication and congruity between fish physiologists and fisheries scientists. © 2017 John Wiley & Sons Ltd.

Small Marine Protected Areas in Fiji Provide Refuge for Reef Fish Assemblages, Feeding Groups, and Corals

PubMed Central

Pires, Mathias M.; Guimarães, Paulo Roberto; Hoey, Andrew S.; Hay, Mark E.

2017-01-01

The establishment of no-take marine protected areas (MPAs) on coral reefs is a common management strategy for conserving the diversity, abundance, and biomass of reef organisms. Generally, well-managed and enforced MPAs can increase or maintain the diversity and function of the enclosed coral reef, with some of the benefits extending to adjacent non-protected reefs. A fundamental question in coral reef conservation is whether these benefits arise within small MPAs (<1 km2), because larval input of reef organisms is largely decoupled from local adult reproduction. We examined the structure of fish assemblages, composition of fish feeding groups, benthic cover, and key ecosystem processes (grazing, macroalgal browsing, and coral replenishment) in three small (0.5–0.8 km2) no-take MPAs and adjacent areas where fisheries are allowed (non-MPAs) on coral reefs in Fiji. The MPAs exhibited greater species richness, density, and biomass of fishes than non-MPAs. Furthermore, MPAs contained a greater abundance and biomass of grazing herbivores and piscivores as well as a greater abundance of cleaners than fished areas. We also found differences in fish associations when foraging, with feeding groups being generally more diverse and having greater biomass within MPAs than adjacent non-MPAs. Grazing by parrotfishes was 3–6 times greater, and macroalgal browsing was 3–5 times greater in MPAs than in non-MPAs. On average, MPAs had 260–280% as much coral cover and only 5–25% as much macroalgal cover as their paired non-MPA sites. Finally, two of the three MPAs had three-fold more coral recruits than adjacent non-MPAs. The results of this study indicate that small MPAs benefit not only populations of reef fishes, but also enhance ecosystem processes that are critical to reef resilience within the MPAs. PMID:28122006

Overwinter survival of juvenile lake herring in relation to body size, physiological condition, energy stores, and food ration

USGS Publications Warehouse

Pangle, Kevin L.; Sutton, Trent M.; Kinnunen, Ronald E.; Hoff, Michael H.

2004-01-01

Populations of lake herring Coregonus artedi in Lake Superior have exhibited high recruitment variability over the past three decades. To improve our understanding of the mechanisms which influence year-class strength, we conducted a 225-d laboratory experiment to evaluate the effects of body size, physiological condition, energy stores, and food ration on the winter survival of age-0 lake herring. Small (total length (TL) range = 60–85 mm) and large (TL range = 86–110 mm) fish were maintained under thermal and photoperiod regimes that mimicked those in Lake Superior from October through May. Fish in each size-class were maintained at two feeding treatments: brine shrimp Artemiaspp. ad libitum and no food. The mortality of large lake herring (fed, 3.8%; starved, 20.1%) was significantly less than that of small fish (fed, 11.7%; starved, 32.0%). Body condition and crude lipid content declined for all fish over the experiment; however, these variables were significantly greater for large fed (0.68% and 9.8%) and small fed (0.65% and 7.3%) fish than large starved (0.49% and 5.7%) and small starved (0.45% and 4.8%) individuals. Final crude protein and gross energy contents were also significantly greater in large fed lake herring (17.6% and 1,966 cal/g), followed by small fed (17.1% and 1,497 cal/g), large starved (15.4% and 1,125 cal/g), and small starved (13.2% and 799 cal/g) fish. Lake herring that died during the experiment had significantly lower body condition and energy stores relative to those of the surviving fish. These results suggest that the depletion of energy stores contributes to greater winter mortality of small lake herring with limited energy uptake and may partially explain the variability in recruitment observed in Lake Superior.

Assessment of the Fishery Improvement Opportunities on the Pend Oreille River, Appendices, 1990 Annual Report.

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

Ashe, Becky L.; Lillengreen, Kelly L.; Vella, John J.

1991-03-01

This report is a compilation of the seven appendices to DOE/BP/39339--4 the annual report for FY 1990. These appendices contain the supporting numerical data for the study. The purpose of this study was to assess the fishery improvement opportunities on the Box Canyon portion of the Pend Oreilla River. This three year study was initiated as part of the Northwest Power Planning Council's 1987 Columbia River Basin Fish and Wildlife Program. This report contains the findings of the third and final year of the study. The objectives of the third year of the study were to determine the relative abundancemore » of each species in the river and sloughs; the population levels in five selected tributaries and, if possible, for fish in the river and sloughs; each species growth rate, feeding habits, abundance of preferred prey, and migration patterns; and the seasonal movement patterns and habitat utilization of largemouth bass.« less

The effects of oil spills on marine fish: Implications of spatial variation in natural mortality.

PubMed

Langangen, Ø; Olsen, E; Stige, L C; Ohlberger, J; Yaragina, N A; Vikebø, F B; Bogstad, B; Stenseth, N C; Hjermann, D Ø

2017-06-15

The effects of oil spills on marine biological systems are of great concern, especially in regions with high biological production of harvested resources such as in the Northeastern Atlantic. The scientific studies of the impact of oil spills on fish stocks tend to ignore that spatial patterns of natural mortality may influence the magnitude of the impact over time. Here, we first illustrate how spatial variation in natural mortality may affect the population impact by considering a thought experiment. Second, we consider an empirically based example of Northeast Arctic cod to extend the concept to a realistic setting. Finally, we present a scenario-based investigation of how the degree of spatial variation in natural mortality affects the impact over a gradient of oil spill sizes. Including the effects of spatial variations in natural mortality tends to widen the impact distribution, hence increasing the probability of both high and low impact events. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Response of fish assemblages to decreasing acid deposition in Adirondack Mountain lakes

USGS Publications Warehouse

Baldigo, Barry P.; Roy, Karen; Driscoll, Charles T.

2016-01-01

The CAA and other federal regulations have clearly reduced emissions of NOx and SOx, acidic deposition, and the acidity and toxicity of waters in the ALTM lakes, but these changes have not triggered widespread recovery of brook trout populations or fish communities. The lack of detectable biological recovery appears to result from relatively recent chemical recovery and an insufficient period for species populations to take advantage of improved water quality. Recovery of extirpated species’ populations may simply require more time for individuals to migrate to and repopulate formerly occupied lakes. Supplemental stocking of selected species may be required in some lakes with no remnant (or nearby) populations or with physical barriers between the recovered lake and source populations. The lack of detectable biological recovery could also be related to our inability to calculate measures of uncertainty or error and, thus, examine temporal changes or differences in populations and community metrics in more depth (e.g., within individual lakes) using existing datasets. Indeed, recovery of brook trout populations and partial recovery of fish communities are documented in several lakes of the region, both with and without human intervention. Multiple fish surveys (annually or within the same year) or the use of mark and recapture methods within individual lakes would help alleviate the issue (provide measures of error for key fishery metrics) within the context of a more focused sampling strategy. Efforts to evaluate and detect recovery in fish assemblages from streams may be more effective than in lakes because various life stages, species’ populations, and entire assemblages are easier to quantify, with known levels of error, in streams than in lakes. Such long-term monitoring efforts could increase our ability to detect and quantify biological recovery in recovering (neutralizing) surface waters throughout the Adirondack Region.

Understanding the Spatial Scale of Genetic Connectivity at Sea: Unique Insights from a Land Fish and a Meta-Analysis.

PubMed

Cooke, Georgina M; Schlub, Timothy E; Sherwin, William B; Ord, Terry J

2016-01-01

Quantifying the spatial scale of population connectivity is important for understanding the evolutionary potential of ecologically divergent populations and for designing conservation strategies to preserve those populations. For marine organisms like fish, the spatial scale of connectivity is generally set by a pelagic larval phase. This has complicated past estimates of connectivity because detailed information on larval movements are difficult to obtain. Genetic approaches provide a tractable alternative and have the added benefit of estimating directly the reproductive isolation of populations. In this study, we leveraged empirical estimates of genetic differentiation among populations with simulations and a meta-analysis to provide a general estimate of the spatial scale of genetic connectivity in marine environments. We used neutral genetic markers to first quantify the genetic differentiation of ecologically-isolated adult populations of a land dwelling fish, the Pacific leaping blenny (Alticus arnoldorum), where marine larval dispersal is the only probable means of connectivity among populations. We then compared these estimates to simulations of a range of marine dispersal scenarios and to collated FST and distance data from the literature for marine fish across diverse spatial scales. We found genetic connectivity at sea was extensive among marine populations and in the case of A. arnoldorum, apparently little affected by the presence of ecological barriers. We estimated that ~5000 km (with broad confidence intervals ranging from 810-11,692 km) was the spatial scale at which evolutionarily meaningful barriers to gene flow start to occur at sea, although substantially shorter distances are also possible for some taxa. In general, however, such a large estimate of connectivity has important implications for the evolutionary and conservation potential of many marine fish communities.

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.

Reproductive biomarkers responses induced by xenoestrogens in the characid fish Astyanax fasciatus inhabiting a South American reservoir: An integrated field and laboratory approach

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

Prado, Paula S.; Pinheiro, Ana Paula B.; Bazzoli, Nilo

2014-05-01

Field studies evaluating the effects of endocrine disruption chemicals (EDCs) on the fish reproduction are scarce worldwide. The goal of this study was to assess hepatic levels of vitellogenin (Vtg), zona radiata proteins (Zrp) and insulin-like growth factors (IGF-I and IGF-II), and relating them to reproductive endpoints in a wild fish population habiting a reservoir that receive domestic sewage, agricultural and industrial residues. Adult fish Astyanax fasciatus were sampled during the reproductive season in five sites from the Furnas Reservoir, Grande River, and Paraguay–Paraná basin. As a control to field data, fish were experimentally exposed via dietary intake, to oestradiolmore » benzoate (OB) for 7 days. Fish from site with little anthropogenic interference showed hepatic levels of Vtg, Zrp and IGF-I and IGF-II similar to those from the non-treated experimental group. In sites located immediately downstream from the municipal wastewater discharges, the water total oestrogen was >120 ng/l, and male fish displayed increased Vtg and Zrp and decreased IGF-I levels similar to OB treated fish. In females, levels of Vtg, Zrp, IGF-I and IGF-II suggest an impairment of final oocyte maturation and spawning, as also detected by frequency of over-ripening, follicular atresia and fecundity. At the sites that receive agricultural and industrial residues, the water total oestrogen was <50 ng/l and females showed decreased Zrp and increased IGF-II levels associated to reduced diameter of vitellogenic follicles, indicating an inhibition of oocyte growth. Overall, the current study reports oestrogenic contamination impairing the reproduction of a wild fish from a hydroeletric reservoir and, the data contribute to improving the current knowledge on relationship between hepatic Vtg, Zrp and IGF-I and IGF-II, and reproductive endpoints in a teleost fish. In addition, our data point out novel reproductive biomarkers (IGF-I, IGF-II and over-ripening) to assessing xenoestrogenic contamination in freshwater ecosystems. - Highlights: • We point out novel reproductive biomarkers to assess xenoestrogenic contamination. • Field captured fish showed altered hepatic Vtg and Zrp. • Hepatic IGF-I and II levels were associated to reproductive disturbances. • Over-ripening is a better xenoestrogen biomarker than follicular atresia.« less

Relationship of the Adherence to a Mediterranean Diet and Its Main Components with CRP Levels in the Spanish Population.

PubMed

Lahoz, Carlos; Castillo, Elisa; Mostaza, Jose M; de Dios, Olaya; Salinero-Fort, Miguel A; González-Alegre, Teresa; García-Iglesias, Francisca; Estirado, Eva; Laguna, Fernando; Sanchez, Vanesa; Sabín, Concesa; López, Silvia; Cornejo, Victor; de Burgos, Carmen; Garcés, Carmen

2018-03-20

Background: Adherence to a Mediterranean diet seems to be inversely associated with C-reactive protein (CRP) concentration. A 14-point Mediterranean Diet Adherence Screener (MEDAS) has been developed to assess dietary compliance. Objective: The aim of this study was to assess whether each of the MEDAS questions as well as their final score were associated with the levels of CRP in general Spanish population. Cross-sectional analysis of 1411 subjects (mean age 61 years, 43.0% males) randomly selected from the general population. CRP levels were determined by a commercial ELISA kit. Adherence to the Mediterranean diet was measured by the 14-point MEDAS. Results: There was an inverse correlation between adherence to the Mediterranean diet and the CRP concentration, even after adjusting by age, gender, hypertension, metabolic syndrome, body mass index, statin treatment and hypertension treatment ( p = 0.041). Subjects who consume ≥2 servings of vegetables per day ( p = 0.003), ≥3 pieces of fruit per day ( p = 0.003), ≥1 serving of butter, margarine, or cream per day ( p = 0.041) or ≥3 servings of fish/seafood per week ( p = 0.058) had significantly lower levels of CRP. Conclusions : Adherence to a Mediterranean-type diet measured by a simple questionnaire is associated with lower CRP concentration. However, this association seems to be particularly related to a higher consumption of vegetables, fruits, dairy products, and fish.

Genetic Architecture of the Variation in Male-Specific Ossified Processes on the Anal Fins of Japanese Medaka.

PubMed

Kawajiri, Maiko; Fujimoto, Shingo; Yoshida, Kohta; Yamahira, Kazunori; Kitano, Jun

2015-10-28

Traits involved in reproduction evolve rapidly and show great diversity among closely related species. However, the genetic mechanisms that underlie the diversification of courtship traits are mostly unknown. Japanese medaka fishes (Oryzias latipes) use anal fins to attract females and to grasp females during courtship; the males have longer anal fins with male-specific ossified papillary processes on the fin rays. However, anal fin morphology varies between populations: the southern populations tend to have longer anal fins and more processes than the northern populations. In the present study, we conducted quantitative trait locus (QTL) mapping to investigate the genetic architecture underlying the variation in the number of papillary processes of Japanese medaka fish and compared the QTL with previously identified QTL controlling anal fin length. First, we found that only a few QTL were shared between anal fin length and papillary process number. Second, we found that the numbers of papillary processes on different fin rays often were controlled by different QTL. Finally, we produced another independent cross and found that some QTL were repeatable between the two crosses, whereas others were specific to only one cross. These results suggest that variation in the number of papillary processes is polygenic and controlled by QTL that are distinct from those controlling anal fin length. Thus, different courtship traits in Japanese medaka share a small number of QTL and have the potential for independent evolution. Copyright © 2015 Kawajiri et al.

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.

Marine Corps Equities in the Arctic

DTIC Science & Technology

2013-04-18

reduces the shipping time from Yokohama, Japan, to Hamburg , Germany, by 11 days as compared to the Suez Canal. Ships average approximately a 20...areas within the Arctic Circle. 10 Warming ocean water is causing fisheries to shift north as well. Fish populations usually found in the...people live in the Arctic region. Commercial fishing fleets are following these populations. 29 Russia holds the majority of the Arctic population

50 CFR 100.16 - Customary and traditional use determination process.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) The Board shall determine which fish stocks and wildlife populations have been customarily and... of specific fish stocks and wildlife populations. For areas managed by the National Park Service... following factors: (1) A long-term consistent pattern of use, excluding interruptions beyond the control of...

50 CFR 100.16 - Customary and traditional use determination process.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) The Board shall determine which fish stocks and wildlife populations have been customarily and... of specific fish stocks and wildlife populations. For areas managed by the National Park Service... following factors: (1) A long-term consistent pattern of use, excluding interruptions beyond the control of...

50 CFR 100.16 - Customary and traditional use determination process.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) The Board shall determine which fish stocks and wildlife populations have been customarily and... of specific fish stocks and wildlife populations. For areas managed by the National Park Service... following factors: (1) A long-term consistent pattern of use, excluding interruptions beyond the control of...

50 CFR 100.16 - Customary and traditional use determination process.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) The Board shall determine which fish stocks and wildlife populations have been customarily and... of specific fish stocks and wildlife populations. For areas managed by the National Park Service... following factors: (1) A long-term consistent pattern of use, excluding interruptions beyond the control of...

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...

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...

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...

Tower counts

USGS Publications Warehouse

Woody, Carol Ann; Johnson, D.H.; Shrier, Brianna M.; O'Neal, Jennifer S.; Knutzen, John A.; Augerot, Xanthippe; O'Neal, Thomas A.; Pearsons, Todd N.

2007-01-01

Counting towers provide an accurate, low-cost, low-maintenance, low-technology, and easily mobilized escapement estimation program compared to other methods (e.g., weirs, hydroacoustics, mark-recapture, and aerial surveys) (Thompson 1962; Siebel 1967; Cousens et al. 1982; Symons and Waldichuk 1984; Anderson 2000; Alaska Department of Fish and Game 2003). Counting tower data has been found to be consistent with that of digital video counts (Edwards 2005). Counting towers do not interfere with natural fish migration patterns, nor are fish handled or stressed; however, their use is generally limited to clear rivers that meet specific site selection criteria. The data provided by counting tower sampling allow fishery managers to determine reproductive population size, estimate total return (escapement + catch) and its uncertainty, evaluate population productivity and trends, set harvest rates, determine spawning escapement goals, and forecast future returns (Alaska Department of Fish and Game 1974-2000 and 1975-2004). The number of spawning fish is determined by subtracting subsistence, sport-caught fish, and prespawn mortality from the total estimated escapement. The methods outlined in this protocol for tower counts can be used to provide reasonable estimates ( plus or minus 6%-10%) of reproductive salmon population size and run timing in clear rivers. 

B-Transform and Its Application to a Fish-Hyacinth Model

ERIC Educational Resources Information Center

Oyelami, B. O.; Ale, S. O.

2002-01-01

A new transform proposed by Oyelami and Ale for impulsive systems is applied to an impulsive fish-hyacinth model. A biological policy regarding the growth of the fish and the hyacinth populations is formulated.

Understanding barotrauma in fish passing hydro structures: a global strategy for sustainable development of water resources

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

Brown, Richard S.; Colotelo, Alison HA; Pflugrath, Brett D.

2014-03-24

Freshwater fishes are one of the most imperiled groups of vertebrates and species declines have been linked to a number of anthropogenic influences. This is alarming as the diversity and stability of populations are at risk. In addition, freshwater fish serve as important protein sources, particularly in developing countries. One of the focal activities thought to influence freshwater fish population declines is water resource development, which is anticipated to increase over the next several decades. For fish encountering hydro structures, such as passing through hydroturbines, there may be a rapid decrease in pressure which can lead to injuries commonly referredmore » to as barotraumas. The authors summarize the research to date that has examined the effects of rapid pressure changes on fish and outline the most important factors to consider (i.e., swim bladder morphology, depth of acclimation, migration pattern and life stage) when examining the susceptibility of barotraumas for fish of interest.« less

Physiological basis of climate change impacts on North American inland fishes

USGS Publications Warehouse

Whitney, James E.; Al-Chokhachy, Robert K.; Bunnell, David B.; Caldwell, Colleen A.; Cooke, Steven J.; Eliason, Erika J.; Rogers, Mark W.; Lynch, Abigail J.; Paukert, Craig P.

2016-01-01

Global climate change is altering freshwater ecosystems and affecting fish populations and communities. Underpinning changes in fish distribution and assemblage-level responses to climate change are individual-level physiological constraints. In this review, we synthesize the mechanistic effects of climate change on neuroendocrine, cardiorespiratory, immune, osmoregulatory, and reproductive systems of freshwater and diadromous fishes. Observed climate change effects on physiological systems are varied and numerous, including exceedance of critical thermal tolerances, decreased cardiorespiratory performance, compromised immune function, and altered patterns of individual reproductive investment. However, effects vary widely among and within species because of species, population, and even sex-specific differences in sensitivity and resilience and because of habitat-specific variation in the magnitude of climate-related environmental change. Research on the interactive effects of climate change with other environmental stressors across a broader range of fish diversity is needed to further our understanding of climate change effects on fish physiology.

Fish assemblages

USGS Publications Warehouse

McGarvey, Daniel J.; Falke, Jeffrey A.; Li, Hiram W.; Li, Judith; Hauer, F. Richard; Lamberti, G.A.

2017-01-01

Methods to sample fishes in stream ecosystems and to analyze the raw data, focusing primarily on assemblage-level (all fish species combined) analyses, are presented in this chapter. We begin with guidance on sample site selection, permitting for fish collection, and information-gathering steps to be completed prior to conducting fieldwork. Basic sampling methods (visual surveying, electrofishing, and seining) are presented with specific instructions for estimating population sizes via visual, capture-recapture, and depletion surveys, in addition to new guidance on environmental DNA (eDNA) methods. Steps to process fish specimens in the field including the use of anesthesia and preservation of whole specimens or tissue samples (for genetic or stable isotope analysis) are also presented. Data analysis methods include characterization of size-structure within populations, estimation of species richness and diversity, and application of fish functional traits. We conclude with three advanced topics in assemblage-level analysis: multidimensional scaling (MDS), ecological networks, and loop analysis.

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.

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 importance of spearfishing in coastal communities where it is practised. PMID:23251656

Rapid evolution leads to differential population dynamics and top-down control in resurrected Daphnia populations.

PubMed

Goitom, Eyerusalem; Kilsdonk, Laurens J; Brans, Kristien; Jansen, Mieke; Lemmens, Pieter; De Meester, Luc

2018-01-01

There is growing evidence of rapid genetic adaptation of natural populations to environmental change, opening the perspective that evolutionary trait change may subsequently impact ecological processes such as population dynamics, community composition, and ecosystem functioning. To study such eco-evolutionary feedbacks in natural populations, however, requires samples across time. Here, we capitalize on a resurrection ecology study that documented rapid and adaptive evolution in a natural population of the water flea Daphnia magna in response to strong changes in predation pressure by fish, and carry out a follow-up mesocosm experiment to test whether the observed genetic changes influence population dynamics and top-down control of phytoplankton. We inoculated populations of the water flea D. magna derived from three time periods of the same natural population known to have genetically adapted to changes in predation pressure in replicate mesocosms and monitored both Daphnia population densities and phytoplankton biomass in the presence and absence of fish. Our results revealed differences in population dynamics and top-down control of algae between mesocosms harboring populations from the time period before, during, and after a peak in fish predation pressure caused by human fish stocking. The differences, however, deviated from our a priori expectations. An S-map approach on time series revealed that the interactions between adults and juveniles strongly impacted the dynamics of populations and their top-down control on algae in the mesocosms, and that the strength of these interactions was modulated by rapid evolution as it occurred in nature. Our study provides an example of an evolutionary response that fundamentally alters the processes structuring population dynamics and impacts ecosystem features.

78 FR 72642 - Pacific Fishery Management Council; Public Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-03

... Groundfish Essential Fish Habitat Review Committee (EFHRC). DATES: The first conference call will be held... discuss and finalize the Phase 2 Report, which summarizes the status of the essential fish habitat...

78 FR 33300 - Endangered and Threatened Wildlife and Plants; 12-Month Finding and Proposed Endangered Listing...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-04

... of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish... joint NMFS and U.S. Fish and Wildlife Service (USFWS) Policy for Evaluating Conservation Efforts (PECE... Rajiformes (skates, rays, and sawfishes) and Class Chondrichthyes (cartilaginous fish), also commonly known...

36 CFR 13.490 - Closure to subsistence uses of fish and wildlife.

Code of Federal Regulations, 2014 CFR

2014-07-01

... of fish and wildlife. 13.490 Section 13.490 Parks, Forests, and Public Property NATIONAL PARK SERVICE... uses of fish and wildlife. (a) Notwithstanding any other provision of this part, the Superintendent... uses of a particular fish or wildlife population only if necessary for reasons of public safety...

36 CFR 13.490 - Closure to subsistence uses of fish and wildlife.

Code of Federal Regulations, 2011 CFR

2011-07-01

... of fish and wildlife. 13.490 Section 13.490 Parks, Forests, and Public Property NATIONAL PARK SERVICE... uses of fish and wildlife. (a) Notwithstanding any other provision of this part, the Superintendent... uses of a particular fish or wildlife population only if necessary for reasons of public safety...

36 CFR 13.490 - Closure to subsistence uses of fish and wildlife.

Code of Federal Regulations, 2012 CFR

2012-07-01

... of fish and wildlife. 13.490 Section 13.490 Parks, Forests, and Public Property NATIONAL PARK SERVICE... uses of fish and wildlife. (a) Notwithstanding any other provision of this part, the Superintendent... uses of a particular fish or wildlife population only if necessary for reasons of public safety...

36 CFR 13.490 - Closure to subsistence uses of fish and wildlife.

Code of Federal Regulations, 2013 CFR

2013-07-01

... of fish and wildlife. 13.490 Section 13.490 Parks, Forests, and Public Property NATIONAL PARK SERVICE... uses of fish and wildlife. (a) Notwithstanding any other provision of this part, the Superintendent... uses of a particular fish or wildlife population only if necessary for reasons of public safety...

36 CFR 13.490 - Closure to subsistence uses of fish and wildlife.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of fish and wildlife. 13.490 Section 13.490 Parks, Forests, and Public Property NATIONAL PARK SERVICE... uses of fish and wildlife. (a) Notwithstanding any other provision of this part, the Superintendent... uses of a particular fish or wildlife population only if necessary for reasons of public safety...

Angling sport fishing in Lobo-Broa reservoir (Itirapina, SP, Brazil).

PubMed

Pereira, J M A; Petrere, M; Ribeiro-Filho, R A

2008-11-01

The objective of this paper was to study angling from September, 2002 to September, 2004 in the Lobo-Broa Reservoir, Itirapina, SP (22 degrees 15' S and 47 degrees 49' W). Interviews (total 1,027) with sport fishers were accomplished in the three main fishing sites (Horto, Píer and Praia). This fishing was practiced with a simple fishing rod and reel, mainly in Horto, where the catches and fishing effort were higher. The catches were mainly composed of Cichlidae (Geophagus brasiliensis, Oreochromis niloticus, Tilapia rendalli and Cichla monoculus). We tried to determine which factors (fishing sites, type of baits and season) and the covariate fishing effort, expressed in number of fishing rods multiplied by fishing time, would affect catches, using a 3 way-ANCOVA. The final model showed that only fishing sites and effort determined the captures of sporting fishing in the reservoir. Some measures for managing fishing practices are discussed.

Fish-Friendly Hydropower Turbine Development & Deployment: Alden Turbine Preliminary Engineering and Model Testing

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

Foust, J.; Hecker, G.; Li, S.

2011-10-01

The Alden turbine was developed through the U.S. Department of Energy's (DOE's) former Advanced Hydro Turbine Systems Program (1994-2006) and, more recently, through the Electric Power Research Institute (EPRI) and the DOE's Wind & Water Power Program. The primary goal of the engineering study described here was to provide a commercially competitive turbine design that would yield fish passage survival rates comparable to or better than the survival rates of bypassing or spilling flow. Although the turbine design was performed for site conditions corresponding to 92 ft (28 m) net head and a discharge of 1500 cfs (42.5 cms), themore » design can be modified for additional sites with differing operating conditions. During the turbine development, design modifications were identified for the spiral case, distributor (stay vanes and wicket gates), runner, and draft tube to improve turbine performance while maintaining features for high fish passage survival. Computational results for pressure change rates and shear within the runner passage were similar in the original and final turbine geometries, while predicted minimum pressures were higher for the final turbine. The final turbine geometry and resulting flow environments are expected to further enhance the fish passage characteristics of the turbine. Computational results for the final design were shown to improve turbine efficiencies by over 6% at the selected operating condition when compared to the original concept. Prior to the release of the hydraulic components for model fabrication, finite element analysis calculations were conducted for the stay vanes, wicket gates, and runner to verify that structural design criteria for stress and deflections were met. A physical model of the turbine was manufactured and tested with data collected for power and efficiency, cavitation limits, runaway speed, axial and radial thrust, pressure pulsations, and wicket gate torque. All parameters were observed to fall within ranges expected for conventional radial flow machines. Based on these measurements, the expected efficiency peak for prototype application is 93.64%. These data were used in the final sizing of the supporting mechanical and balance of plant equipment. The preliminary equipment cost for the design specification is $1450/kW with a total supply schedule of 28 months. This equipment supply includes turbine, generator, unit controls, limited balance of plant equipment, field installation, and commissioning. Based on the selected head and flow design conditions, fish passage survival through the final turbine is estimated to be approximately 98% for 7.9-inch (200-mm) fish, and the predicted survival reaches 100% for fish 3.9 inches (100 mm) and less in length. Note that fish up to 7.9- inches (200 mm) in length make up more than 90% of fish entrained at hydro projects in the United States. Completion of these efforts provides a mechanical and electrical design that can be readily adapted to site-specific conditions with additional engineering development comparable to costs associated with conventional turbine designs.« less

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

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.

Modeling seasonal dynamics of the small fish cohorts in fluctuating freshwater marsh landscapes

USGS Publications Warehouse

Jopp, Fred; DeAngelis, Donald L.; Trexler, Joel C.

2010-01-01

Small-bodied fishes constitute an important assemblage in many wetlands. In wetlands that dry periodically except for small permanent waterbodies, these fishes are quick to respond to change and can undergo large fluctuations in numbers and biomasses. An important aspect of landscapes that are mixtures of marsh and permanent waterbodies is that high rates of biomass production occur in the marshes during flooding phases, while the permanent waterbodies serve as refuges for many biotic components during the dry phases. The temporal and spatial dynamics of the small fishes are ecologically important, as these fishes provide a crucial food base for higher trophic levels, such as wading birds. We develop a simple model that is analytically tractable, describing the main processes of the spatio-temporal dynamics of a population of small-bodied fish in a seasonal wetland environment, consisting of marsh and permanent waterbodies. The population expands into newly flooded areas during the wet season and contracts during declining water levels in the dry season. If the marsh dries completely during these times (a drydown), the fish need refuge in permanent waterbodies. At least three new and general conclusions arise from the model: (1) there is an optimal rate at which fish should expand into a newly flooding area to maximize population production; (2) there is also a fluctuation amplitude of water level that maximizes fish production, and (3) there is an upper limit on the number of fish that can reach a permanent waterbody during a drydown, no matter how large the marsh surface area is that drains into the waterbody. Because water levels can be manipulated in many wetlands, it is useful to have an understanding of the role of these fluctuations.

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.

Correlation Between Existence of Reef Sharks with Abundance of Reef Fishes in South Waters of Morotai Island (North Moluccas)

NASA Astrophysics Data System (ADS)

Mukharror, Darmawan Ahmad; Tiara Baiti, Isnaini; Ichsan, Muhammad; Pridina, Niomi; Triutami, Sanny

2017-10-01

Despite increasing academic research citation on biology, abundance, and the behavior of the blacktip reef sharks, the influence of reef fish population on the density of reef sharks: Carcharhinus melanopterus and Triaenodon obesus population in its habitat were largely unassessed. This present study examined the correlation between abundance of reef fishes family/species with the population of reef sharks in Southern Waters of Morotai Island. The existence of reef sharks was measured with the Audible Stationary Count (ASC) methods and the abundance of reef fishes was surveyed using Underwater Visual Census (UVC) combined with Diver Operated Video (DOV) census. The coefficient of Determination (R2) was used to investigate the degree of relationships between sharks and the specific reef fishes species. The research from 8th April to 4th June 2015 showed the strong positive correlations between the existence of reef sharks with abundance of reef fishes. The correlation values between Carcharhinus melanopterus/Triaenodon obesus with Chaetodon auriga was 0.9405, blacktip/whitetip reef sharks versus Ctenochaetus striatus was 0.9146, and Carcharhinus melanopterus/Triaenodon obesus to Chaetodon kleinii was 0.8440. As the shark can be worth more alive for shark diving tourism than dead in a fish market, the abundance of these reef fishes was important as an early indication parameter of shark existence in South Water of Morotai Island. In the long term, this highlights the importance of reef fishes abundance management in Morotai Island’s Waters to enable the establishment of appropriate and effective reef sharks conservation.

Vitamin A intoxication from reef fish liver consumption in Bermuda.

PubMed

Dewailly, E; Rouja, P; Schultz, E; Julien, P; Tucker, T

2011-09-01

We report three historical cases of severe vitamin A intoxication in anglers who had consumed reef fish liver caught in Bermuda. The subsequent analyses of 35 fish livers from seven different fish species revealed that very high concentrations of vitamin A exist in tropical fish liver, even in noncarnivorous fish species. Large variations in concentrations were observed between specimens and between species. The angling population and (especially) pregnant women should be advised of this potential health threat.

78 FR 60766 - Endangered and Threatened Wildlife and Plants; Threatened Species Status for Spring Pygmy Sunfish

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-02

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R4-ES-2012... Pygmy Sunfish AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine threatened species status under the Endangered Species...

76 FR 50680 - Endangered and Threatened Wildlife and Plants; Removal of the Lake Erie Watersnake (Nerodia...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-16

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R3-ES-2010... Threatened Wildlife AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule; notice of availability... of 1973, as amended (Act), we, the U.S. Fish and Wildlife Service (Service), are removing the Lake...

78 FR 69569 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Jemez...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-20

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R2-ES-2013... Habitat for the Jemez Mountains Salamander AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and Wildlife Service, designate critical habitat for the Jemez Mountains...

76 FR 35349 - Endangered and Threatened Wildlife and Plants; Reinstatement of Listing Protections for the...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-17

... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R5-ES-2011...; Reinstatement of Listing Protections for the Virginia Northern Flying Squirrel in Compliance With a Court Order AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY: We, the U.S. Fish and Wildlife...

21 CFR 172.340 - Fish protein isolate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Fish protein isolate. 172.340 Section 172.340 Food... conditions: (1) The additive shall consist principally of dried fish protein prepared from the edible.... (1) Protein content, as N × 6.25, shall not be less than 90 percent by weight of the final product...

21 CFR 172.340 - Fish protein isolate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Fish protein isolate. 172.340 Section 172.340 Food... conditions: (1) The additive shall consist principally of dried fish protein prepared from the edible.... (1) Protein content, as N × 6.25, shall not be less than 90 percent by weight of the final product...

21 CFR 172.340 - Fish protein isolate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Fish protein isolate. 172.340 Section 172.340 Food... conditions: (1) The additive shall consist principally of dried fish protein prepared from the edible.... (1) Protein content, as N × 6.25, shall not be less than 90 percent by weight of the final product...

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...

The influence of density on adults and juveniles of the estuarine fish, the sheepshead minnow (cyprinodon variegatus)

EPA Science Inventory

The relationship between population density and demographic rates (e.g. survival, reproduction, growth) is critical to understand population dynamics and has been widely studied in fishes. Estuarine species are regularly exposed to dramatic changes in density with daily, monthly,...

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.

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...

Sport fish consumption and body burden levels of chlorinated hydrocarbons: a study of Wisconsin anglers

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

Fiore, B.J.; Anderson, H.A.; Hanrahan, L.P.

1989-03-01

Sport-caught fish consumption is the major source of polychlorinated biphenyls (PCBs) exposure for the general population. To assess this and 2,2'-bis-(p-chlorophenyl)-1,1-dichloroethylene (DDE) exposure, we surveyed 801 Wisconsin anglers for fishing and consumption habits and comprehension of and compliance with the Wisconsin fish consumption health advisory. The mean annual number of sport-caught fish meals was 18. Seventy-two percent of anglers were familiar with the health advisory and 57% had changed their fishing or fish consumption habits as a result of the advisory. The mean PCB serum congener sum level for 192 anglers was 2.2 micrograms/l (range = nondetectable to 27.1 micrograms/l);more » mean DDE was 6.3 micrograms/l (range = nondetectable to 40.0 micrograms/l). Statistically significant positive Spearman correlations were observed between sport-caught fish meals and PCB and DDE sera levels (R = .21 and .14, respectively) and between kilograms of fish caught and PCB sera levels (R = .25). These results demonstrate that anglers may provide a population for assessment of PCBs and DDE associated morbidity and mortality.« less

Perspectives: Gene Expression in Fisheries Management

USGS Publications Warehouse

Nielsen, Jennifer L.; Pavey, Scott A.

2010-01-01

Functional genes and gene expression have been connected to physiological traits linked to effective production and broodstock selection in aquaculture, selective implications of commercial fish harvest, and adaptive changes reflected in non-commercial fish populations subject to human disturbance and climate change. Gene mapping using single nucleotide polymorphisms (SNPs) to identify functional genes, gene expression (analogue microarrays and real-time PCR), and digital sequencing technologies looking at RNA transcripts present new concepts and opportunities in support of effective and sustainable fisheries. Genomic tools have been rapidly growing in aquaculture research addressing aspects of fish health, toxicology, and early development. Genomic technologies linking effects in functional genes involved in growth, maturation and life history development have been tied to selection resulting from harvest practices. Incorporating new and ever-increasing knowledge of fish genomes is opening a different perspective on local adaptation that will prove invaluable in wild fish conservation and management. Conservation of fish stocks is rapidly incorporating research on critical adaptive responses directed at the effects of human disturbance and climate change through gene expression studies. Genomic studies of fish populations can be generally grouped into three broad categories: 1) evolutionary genomics and biodiversity; 2) adaptive physiological responses to a changing environment; and 3) adaptive behavioral genomics and life history diversity. We review current genomic research in fisheries focusing on those that use microarrays to explore differences in gene expression among phenotypes and within or across populations, information that is critically important to the conservation of fish and their relationship to humans.

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 erratic and variable than population growth in the Coosa River. We encourage ecologists to develop similar models for other lotic species, particularly in regulated river systems. Successful management of fish populations in regulated systems requires that we are able to predict how hydrology affects recruitment and will ultimately influence the population dynamics of fishes. ?? 2010 by the Ecological Society of America.

Using population models to evaluate management alternatives for Gulf Striped Bass

USGS Publications Warehouse

Aspinwall, Alexander P.; Irwin, Elise R.; Lloyd, M. Clint

2017-01-01

Interstate management of Gulf Striped Bass Morone saxatilis has involved a thirty-year cooperative effort involving Federal and State agencies in Georgia, Florida and Alabama (Apalachicola-Chattahoochee-Flint Gulf Striped Bass Technical Committee). The Committee has recently focused on developing an adaptive framework for conserving and restoring Gulf Striped Bass in the Apalachicola, Chattahoochee, and Flint River (ACF) system. To evaluate the consequences and tradeoffs among management activities, population models were used to inform management decisions. Stochastic matrix models were constructed with varying recruitment and stocking rates to simulate effects of management alternatives on Gulf Striped Bass population objectives. An age-classified matrix model that incorporated stock fecundity estimates and survival estimates was used to project population growth rate. In addition, combinations of management alternatives (stocking rates, Hydrilla control, harvest regulations) were evaluated with respect to how they influenced Gulf Striped Bass population growth. Annual survival and mortality rates were estimated from catch-curve analysis, while fecundity was estimated and predicted using a linear least squares regression analysis of fish length versus egg number from hatchery brood fish data. Stocking rates and stocked-fish survival rates were estimated from census data. Results indicated that management alternatives could be an effective approach to increasing the Gulf Striped Bass population. Population abundance was greatest under maximum stocking effort, maximum Hydrilla control and a moratorium. Conversely, population abundance was lowest under no stocking, no Hydrilla control and the current harvest regulation. Stocking rates proved to be an effective management strategy; however, low survival estimates of stocked fish (1%) limited the potential for population growth. Hydrilla control increased the survival rate of stocked fish and provided higher estimates of population abundances than maximizing the stocking rate. A change in the current harvest regulation (50% harvest regulation) was not an effective alternative to increasing the Gulf Striped Bass population size. Applying a moratorium to the Gulf Striped Bass fishery increased survival rates from 50% to 74% and resulted in the largest population growth of the individual management alternatives. These results could be used by the Committee to inform management decisions for other populations of Striped Bass in the Gulf Region.

Mitochondrial and Allozyme Genetics of Incipient Speciation in a Landlocked Population of Galaxias Truttaceus (Pisces: Galaxiidae)

PubMed Central

Ovenden, J. R.; White, RWG.

1990-01-01

Galaxias truttaceus is found in coastal rivers and streams in south-eastern Australia. It spawns at the head of estuaries in autumn and the larvae spend 3 months of winter at sea before returning to fresh water. In Tasmania there are landlocked populations of G. truttaceus in a cluster of geologically young lakes on the recently glaciated Central Plateau. These populations have no marine larval stage and spawn in the lakes in spring. Speciation due to land locking is thought to be a frequent occurrence within Galaxias. To investigate the nature of the speciation event which may be occurring within lake populations of G. truttaceus we studied the mitochondrial DNA (mtDNA) and allozyme diversity of both lake and stream populations. Using the presence or absence of restriction sites recognized by 13 six-base restriction endonucleases, we found 58 mtDNA haplotypes among 150 fish collected from 13 Tasmanian and one south-east Australian mainland stream populations. The most parsimonious network relating the haplotypes by site loss or gain was starlike in shape. We argue that this arrangement is best explained by selection upon slightly beneficial mutations within the mitochondrial genome. Gene diversity analysis under Wright's island model showed that the populations in each drainage were not genetically subdivided. Only two of these stream haplotypes were found among the 66 fish analyzed from four lake populations. Despite the extreme lack of mtDNA diversity in lake populations, the observed nuclear DNA heterozygosity of 40 lake fish (0.10355) was only slightly less than that of 82 stream fish (0.11635). In the short time (3000-7000 years) that the lake fish have been landlocked, random genetic drift in a finite, stable-sized population was probably not responsible for the lack of mtDNA diversity in the lake populations. We infer the lake populations have probably experienced at least one, severe, but transitory bottleneck possibly induced by natural selection for life-history characters essential for survival in the lacustrine habitat. If speciation is occurring in the landlocked populations of G. truttaceus, then it may be driven by genetic transilience. PMID:2155855

Climate, Anchovy, and Sardine.

PubMed

Checkley, David M; Asch, Rebecca G; Rykaczewski, Ryan R

2017-01-03

Anchovy and sardine populated productive ocean regions over hundreds of thousands of years under a naturally varying climate, and are now subject to climate change of equal or greater magnitude occurring over decades to centuries. We hypothesize that anchovy and sardine populations are limited in size by the supply of nitrogen from outside their habitats originating from upwelling, mixing, and rivers. Projections of the responses of anchovy and sardine to climate change rely on a range of model types and consideration of the effects of climate on lower trophic levels, the effects of fishing on higher trophic levels, and the traits of these two types of fish. Distribution, phenology, nutrient supply, plankton composition and production, habitat compression, fishing, and acclimation and adaptation may be affected by ocean warming, acidification, deoxygenation, and altered hydrology. Observations of populations and evaluation of model skill are essential to resolve the effects of climate change on these fish.

Climate, Anchovy, and Sardine

NASA Astrophysics Data System (ADS)

Checkley, David M.; Asch, Rebecca G.; Rykaczewski, Ryan R.

2017-01-01

Anchovy and sardine populated productive ocean regions over hundreds of thousands of years under a naturally varying climate, and are now subject to climate change of equal or greater magnitude occurring over decades to centuries. We hypothesize that anchovy and sardine populations are limited in size by the supply of nitrogen from outside their habitats originating from upwelling, mixing, and rivers. Projections of the responses of anchovy and sardine to climate change rely on a range of model types and consideration of the effects of climate on lower trophic levels, the effects of fishing on higher trophic levels, and the traits of these two types of fish. Distribution, phenology, nutrient supply, plankton composition and production, habitat compression, fishing, and acclimation and adaptation may be affected by ocean warming, acidification, deoxygenation, and altered hydrology. Observations of populations and evaluation of model skill are essential to resolve the effects of climate change on these fish.

Protecting marine mammals, turtles, and birds by rebuilding global fisheries.

PubMed

Burgess, Matthew G; McDermott, Grant R; Owashi, Brandon; Peavey Reeves, Lindsey E; Clavelle, Tyler; Ovando, Daniel; Wallace, Bryan P; Lewison, Rebecca L; Gaines, Steven D; Costello, Christopher

2018-03-16

Reductions in global fishing pressure are needed to end overfishing of target species and maximize the value of fisheries. We ask whether such reductions would also be sufficient to protect non-target species threatened as bycatch. We compare changes in fishing pressure needed to maximize profits from 4713 target fish stocks-accounting for >75% of global catch-to changes in fishing pressure needed to reverse ongoing declines of 20 marine mammal, sea turtle, and seabird populations threatened as bycatch. We project that maximizing fishery profits would halt or reverse declines of approximately half of these threatened populations. Recovering the other populations would require substantially greater effort reductions or targeting improvements. Improving commercial fishery management could thus yield important collateral benefits for threatened bycatch species globally. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

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.

Climate, invasive species and land use drive population dynamics of a cold-water specialist

USGS Publications Warehouse

Kovach, Ryan P.; Al-Chokhachy, Robert K.; Whited, Diane C.; Schmetterling, David A.; Dux, Andrew M; Muhlfeld, Clint C.

2017-01-01

Climate change is an additional stressor in a complex suite of threats facing freshwater biodiversity, particularly for cold-water fishes. Research addressing the consequences of climate change on cold-water fish has generally focused on temperature limits defining spatial distributions, largely ignoring how climatic variation influences population dynamics in the context of other existing stressors.We used long-term data from 92 populations of bull trout Salvelinus confluentus – one of North America's most cold-adapted fishes – to quantify additive and interactive effects of climate, invasive species and land use on population dynamics (abundance, variability and growth rate).Populations were generally depressed, more variable and declining where spawning and rearing stream habitat was limited, invasive species and land use were prevalent and stream temperatures were highest. Increasing stream temperature acted additively and independently, whereas land use and invasive species had additive and interactive effects (i.e. the impact of one stressor depended on exposure to the other stressor).Most (58%–78%) of the explained variation in population dynamics was attributed to the presence of invasive species, differences in life history and management actions in foraging habitats in rivers, lakes and reservoirs. Although invasive fishes had strong negative effects on populations in foraging habitats, proactive control programmes appeared to effectively temper their negative impact.Synthesis and applications. Long-term demographic data emphasize that climate warming will exacerbate imperilment of cold-water specialists like bull trout, yet other stressors – especially invasive fishes – are immediate threats that can be addressed by proactive management actions. Therefore, climate-adaptation strategies for freshwater biodiversity should consider existing abiotic and biotic stressors, some of which provide potential and realized opportunity for conservation of freshwater biodiversity in a warming world.

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.

Mammalian metabolic rates in the hottest fish on earth

PubMed Central

Wood, Chris M.; Brix, Kevin V.; De Boeck, Gudrun; Bergman, Harold L.; Bianchini, Adalto; Bianchini, Lucas F.; Maina, John N.; Johannsson, Ora E.; Kavembe, Geraldine D.; Papah, Michael B.; Letura, Kisipan M.; Ojoo, Rodi O.

2016-01-01

The Magadi tilapia, Alcolapia grahami, a small cichlid fish of Lake Magadi, Kenya lives in one of the most challenging aquatic environments on earth, characterized by very high alkalinity, unusual water chemistry, and extreme O2, ROS, and temperature regimes. In contrast to most fishes which live at temperatures substantially lower than the 36–40 °C of mammals and birds, an isolated population (South West Hot Springs, SWHS) of Magadi tilapia thrives in fast-flowing hotsprings with daytime highs of 43 °C and night-time lows of 32 °C. Another population (Fish Springs Lagoon, FSL) lives in a lagoon with fairly stable daily temperatures (33–36 °C). The upper critical temperatures (Ctmax) of both populations are very high; moreover the SWHS tilapia exhibit the highest Ctmax (45.6 °C) ever recorded for a fish. Routine rates of O2 consumption (MO2) measured on site, together with MO2 and swimming performance at 25, 32, and 39 °C in the laboratory, showed that the SWHS tilapia exhibited the greatest metabolic performance ever recorded in a fish. These rates were in the basal range of a small mammal of comparable size, and were all far higher than in the FSL fish. The SWHS tilapia represents a bellwether organism for global warming. PMID:27257105

On the reproductive success of early-generation hatchery fish in the wild

PubMed Central

Christie, Mark R; Ford, Michael J; Blouin, Michael S

2014-01-01

Large numbers of hatchery salmon spawn in wild populations each year. Hatchery fish with multiple generations of hatchery ancestry often have heritably lower reproductive success than wild fish and may reduce the fitness of an entire population. Whether this reduced fitness also occurs for hatchery fish created with local- and predominantly wild-origin parents remains controversial. Here, we review recent studies on the reproductive success of such ‘early-generation’ hatchery fish that spawn in the wild. Combining 51 estimates from six studies on four salmon species, we found that (i) early-generation hatchery fish averaged only half the reproductive success of their wild-origin counterparts when spawning in the wild, (ii) the reduction in reproductive success was more severe for males than for females, and (iii) all species showed reduced fitness due to hatchery rearing. We review commonalities among studies that point to possible mechanisms (e.g., environmental versus genetic effects). Furthermore, we illustrate that sample sizes typical of these studies result in low statistical power to detect fitness differences unless the differences are substantial. This review demonstrates that reduced fitness of early-generation hatchery fish may be a general phenomenon. Future research should focus on determining the causes of those fitness reductions and whether they lead to long-term reductions in the fitness of wild populations. PMID:25469167

Reversed sex change by widowed males in polygynous and protogynous fishes: female removal experiments in the field.

PubMed

Kuwamura, Tetsuo; Suzuki, Shohei; Kadota, Tatsuru

2011-12-01

Sex change, either protogyny (female to male) or protandry (male to female), is well known among fishes, but evidence of bidirectional sex change or reversed sex change in natural populations is still very limited. This is the first report on female removal experiments for polygnous and protogynous fish species to induce reversed sex change in the widowed males in the field. We removed all of the females and juveniles from the territories of dominant males in the cleaner wrasse Labroides dimidiatus (Labridae) and the rusty angelfish Centropyge ferrugata (Pomacanthidae) on the coral reefs of Okinawa. In both species, if new females or juveniles did not immigrate into the territories of the widowed males, some of them emigrated to form male-male pairs. When a male-male pair formed, the smaller, subordinate partner began to perform female sexual behaviours (n = 4 in L. dimidiatus; n = 2 in C. ferrugata) and, finally, released eggs (n = 1, respectively). Thus, the reversed sex change occurred in the widowed males according to the change of their social status. These results suggest that such female removal experiments will contribute to the discovery of reversed sex change in the field also in other polygnous and protogynous species.

Reversed sex change by widowed males in polygynous and protogynous fishes: female removal experiments in the field

NASA Astrophysics Data System (ADS)

Kuwamura, Tetsuo; Suzuki, Shohei; Kadota, Tatsuru

2011-12-01

Sex change, either protogyny (female to male) or protandry (male to female), is well known among fishes, but evidence of bidirectional sex change or reversed sex change in natural populations is still very limited. This is the first report on female removal experiments for polygnous and protogynous fish species to induce reversed sex change in the widowed males in the field. We removed all of the females and juveniles from the territories of dominant males in the cleaner wrasse Labroides dimidiatus (Labridae) and the rusty angelfish Centropyge ferrugata (Pomacanthidae) on the coral reefs of Okinawa. In both species, if new females or juveniles did not immigrate into the territories of the widowed males, some of them emigrated to form male-male pairs. When a male-male pair formed, the smaller, subordinate partner began to perform female sexual behaviours ( n = 4 in L. dimidiatus; n = 2 in C. ferrugata) and, finally, released eggs ( n = 1, respectively). Thus, the reversed sex change occurred in the widowed males according to the change of their social status. These results suggest that such female removal experiments will contribute to the discovery of reversed sex change in the field also in other polygnous and protogynous species.

The role of microorganisms in the degradation of adenosine triphosphate (ATP) in chill-stored common carp (Cyprinus carpio) fillets.

PubMed

Li, Dapeng; Zhang, Longteng; Song, Sijia; Wang, Zhiying; Kong, Chunli; Luo, Yongkang

2017-06-01

Biochemical and microbial changes after harvest strongly affect the final quality and shelf life of fish and fish products. In this study, the role of microbes in the degradation of adenosine triphosphate (ATP), and the origin of adenosine monophosphate deaminase (AMPD) and acid phosphatase (ACP) in common carp fillets during different stages of chilled storage (at 4°C) were investigated. The content of ATP, ADP, AMP, IMP, HxR, and Hx, the activity of AMPD and ACP, and the total count of viable, Aeromonas, Pseudomonas, H 2 S-producing bacteria, and lactic acid bacteria were examined. Results indicated that the population of microbial communities in control samples increased with storage time, and Pseudomonas peaked on the 10th day of storage. Changes in AMPD activity were less related to the abundance of microbes during the entire storage period. However, ACP was derived from both fish muscle and microbial secretion during the middle and late stages of storage. Degradation of ATP to IMP was not affected by spoilage bacteria, but the hydrolysis of IMP, and the transformation of HxR to Hx was affected considerably by the spoilage bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interaction of rearing environment and reproductive tactic on gene expression profiles in Atlantic salmon

USGS Publications Warehouse

Aubin-Horth, N.; Letcher, B.H.; Hofmann, H.A.

2005-01-01

Organisms that share the same genotype can develop into divergent phenotypes, depending on environmental conditions. In Atlantic salmon, young males of the same age can be found either as sneakers or immature males that are future anadromous fish. Just as the organism-level phenotype varies between divergent male developmental trajectories, brain gene expression is expected to vary as well. We hypothesized that rearing environment can also have an important effect on gene expression in the brain and possibly interact with the reproductive tactic adopted. We tested this hypothesis by comparing brain gene expression profiles of the two male tactics in fish from the same population that were reared in either a natural stream or under laboratory conditions. We found that expression of certain genes was affected by rearing environment only, while others varied between male reproductive tactics independent of rearing environment. Finally, more than half of all genes that showed variable expression varied between the two male tactics only in one environment. Thus, in these fish, very different molecular pathways can give rise to similar macro-phenotypes depending on rearing environment. This result gives important insights into the molecular underpinnings of developmental plasticity in relationship to the environment. ?? 2005 The American Genetic Association.

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...

Mapping the unknown: Modeling future scenarios of riverine fish communities

EPA Science Inventory

Riverscapes can be defined by spatial and temporal variation in a suite of environmental conditions that influence the distribution and persistence of riverine fish populations. Fish in riverscapes can exhibit extensive movements, require seasonally-distinct habitats for spawnin...

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...

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

PubMed Central

Barham, Barbara J.; Barham, Peter J.; Campbell, Kate J.; Crawford, Robert J. M.; Grigg, Jennifer; Horswill, Cat; Morris, Taryn L.; Pichegru, Lorien; Steinfurth, Antje; Weller, Florian; Winker, Henning

2018-01-01

Global forage-fish landings are increasing, with potentially grave consequences for marine ecosystems. Predators of forage fish may be influenced by this harvest, but the nature of these effects is contentious. Experimental fishery manipulations offer the best solution to quantify population-level impacts, but are rare. We used Bayesian inference to examine changes in chick survival, body condition and population growth rate of endangered African penguins Spheniscus demersus in response to 8 years of alternating time–area closures around two pairs of colonies. Our results demonstrate that fishing closures improved chick survival and condition, after controlling for changing prey availability. However, this effect was inconsistent across sites and years, highlighting the difficultly of assessing management interventions in marine ecosystems. Nevertheless, modelled increases in population growth rates exceeded 1% at one colony; i.e. the threshold considered biologically meaningful by fisheries management in South Africa. Fishing closures evidently can improve the population trend of a forage-fish-dependent predator—we therefore recommend they continue in South Africa and support their application elsewhere. However, detecting demographic gains for mobile marine predators from small no-take zones requires experimental time frames and scales that will often exceed those desired by decision makers. PMID:29343602

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...

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...

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…

Phytoplankton IF-FISH: Species-specific labeling of cellular proteins by immunofluorescence (IF) with simultaneous species identification by fluorescence immunohybridization (FISH).

PubMed

Meek, Megan E; Van Dolah, Frances M

2016-05-01

Phytoplankton rarely occur as unialgal populations. Therefore, to study species-specific protein expression, indicative of physiological status in natural populations, methods are needed that will both assay for a protein of interest and identify the species expressing it. Here we describe a protocol for IF-FISH, a dual labeling procedure using immunofluorescence (IF) labeling of a protein of interest followed by fluorescence in situ hybridization (FISH) to identify the species expressing that protein. The protocol was developed to monitor expression of the cell cycle marker proliferating cell nuclear antigen (PCNA) in the red tide dinoflagellate, Karenia brevis, using a large subunit (LSU) rRNA probe to identify K. brevis in a mixed population of morphologically similar Karenia species. We present this protocol as proof of concept that IF-FISH can be successfully applied to phytoplankton cells. This method is widely applicable for the analysis of single-cell protein expression of any protein of interest within phytoplankton communities. Copyright © 2016 Elsevier B.V. All rights reserved.

Strategies to control a common carp population by pulsed commercial harvest

USGS Publications Warehouse

Colvin, Michael E.; Pierce, Clay; Stewart, Timothy W.; Grummer, Scott E.

2012-01-01

Commercial fisheries are commonly used to manage nuisance fishes in freshwater systems, but such efforts are often unsuccessful. Strategies for successfully controlling a nuisance population of common carp Cyprinus carpio by pulsed commercial harvest were evaluated with a combination of (1) field sampling, (2) population estimation and CPUE indexing, and (3) simulation using an exponential semidiscrete biomass dynamics model (SDBDM). The range of annual fishing mortalities (F) that resulted in successful control (F = 0.244–0.265) was narrow. Common carp biomass dynamics were sensitive to unintentional underharvest due to high rates of surplus production and a biomass doubling time of 2.7 years. Simulations indicated that biomanipulation never achieved successful control unless supplemental fishing mortality was imposed. Harvest of a majority of annual production was required to achieve successful control, as indicated by the ecotrophic coefficient (EC). Readily available biomass data and tools such as SDBDMs and ECs can be used in an adaptive management framework to successfully control common carp and other nuisance fishes by pulsed commercial fishing.

Science to support aquatic animal health

USGS Publications Warehouse

Purcell, Maureen K.; Harris, M. Camille

2016-10-18

Healthy aquatic ecosystems are home to a diversity of plants, invertebrates, fish and wildlife. Aquatic animal populations face unprecedented threats to their health and survival from climate change, water shortages, habitat alteration, invasive species and environmental contaminants. These environmental stressors can directly impact the prevalence and severity of disease in aquatic populations. For example, periodic fish kills in the upper Chesapeake Bay Watershed are associated with many different opportunistic pathogens that proliferate in stressed fish populations. An estimated 80 percent of endangered juvenile Puget Sound steelhead trout die within two weeks of entering the marine environment, and a role for disease in these losses is being investigated. The introduction of viral hemorrhagic septicemia virus (VHSV) into the Great Lakes—a fishery worth an estimated 7 billion dollars annually—resulted in widespread fish die-offs and virus detections in 28 different fish species. Millions of dying sea stars along the west coast of North America have led to investigations into sea star wasting disease. U.S. Geological Survey (USGS) scientists are assisting managers with these issues through ecological investigations of aquatic animal diseases, field surveillance, and research to promote the development of mitigation strategies.

The trout fishery in Shenandoah National Park

USGS Publications Warehouse

Lennon, Robert E.

1961-01-01

Populations of brook trout in streams of Shenandoah National Park were reduced drastically early in the past decade by a succession of unusually severe droughts and floods. The drying of stream beds, predation, and scouring were principal factors in the loss of fish. The park was closed to fishing in 1954 and 1955 to protect survivors. The small numbers of survivors quickly repopulated the streams after drought conditions abated. The stocking of hatchery-reared fingerling trout in selected waters failed to augment the recovery of populations. Survival and growth of young, wild trout were especially good. Their redistribution through miles of previously dry streams was rapid. The park was opened again to fishing in 1956 under regulations which restrict the take but afford an increase in sporting opportunity. Two streams were placed under fishing-for-fun-only regulations in 1961.The welfare of the trout populations is dependent mostly on the weather cycle . Fish may be abundant in wet years but very scarc e in dry ones. Thus, the stream must be managed a s marginal for trout.

Population viability analysis for endangered Roanoke logperch

USGS Publications Warehouse

Roberts, James H.; Angermeier, Paul; Anderson, Gregory B.

2016-01-01

A common strategy for recovering endangered species is ensuring that populations exceed the minimum viable population size (MVP), a demographic benchmark that theoretically ensures low long-term extinction risk. One method of establishing MVP is population viability analysis, a modeling technique that simulates population trajectories and forecasts extinction risk based on a series of biological, environmental, and management assumptions. Such models also help identify key uncertainties that have a large influence on extinction risk. We used stochastic count-based simulation models to explore extinction risk, MVP, and the possible benefits of alternative management strategies in populations of Roanoke logperch Percina rex, an endangered stream fish. Estimates of extinction risk were sensitive to the assumed population growth rate and model type, carrying capacity, and catastrophe regime (frequency and severity of anthropogenic fish kills), whereas demographic augmentation did little to reduce extinction risk. Under density-dependent growth, the estimated MVP for Roanoke logperch ranged from 200 to 4200 individuals, depending on the assumed severity of catastrophes. Thus, depending on the MVP threshold, anywhere from two to all five of the logperch populations we assessed were projected to be viable. Despite this uncertainty, these results help identify populations with the greatest relative extinction risk, as well as management strategies that might reduce this risk the most, such as increasing carrying capacity and reducing fish kills. Better estimates of population growth parameters and catastrophe regimes would facilitate the refinement of MVP and extinction-risk estimates, and they should be a high priority for future research on Roanoke logperch and other imperiled stream-fish species.

Relationship of farm salmon, sea lice, and wild salmon populations.

PubMed

Marty, Gary D; Saksida, Sonja M; Quinn, Terrance J

2010-12-28

Increased farm salmon production has heightened concerns about the association between disease on farm and wild fish. The controversy is particularly evident in the Broughton Archipelago of Western Canada, where a high prevalence of sea lice (ectoparasitic copepods) was first reported on juvenile wild pink salmon (Oncorhynchus gorbuscha) in 2001. Exposure to sea lice from farmed Atlantic salmon (Salmo salar) was thought to be the cause of the 97% population decline before these fish returned to spawn in 2002, although no diagnostic investigation was done to rule out other causes of mortality. To address the concern that sea lice from fish farms would cause population extinction of wild salmon, we analyzed 10-20 y of fish farm data and 60 y of pink salmon data. We show that the number of pink salmon returning to spawn in the fall predicts the number of female sea lice on farm fish the next spring, which, in turn, accounts for 98% of the annual variability in the prevalence of sea lice on outmigrating wild juvenile salmon. However, productivity of wild salmon is not negatively associated with either farm lice numbers or farm fish production, and all published field and laboratory data support the conclusion that something other than sea lice caused the population decline in 2002. We conclude that separating farm salmon from wild salmon--proposed through coordinated fallowing or closed containment--will not increase wild salmon productivity and that medical analysis can improve our understanding of complex issues related to aquaculture sustainability.

Relationship of farm salmon, sea lice, and wild salmon populations

PubMed Central

Marty, Gary D.; Saksida, Sonja M.; Quinn, Terrance J.

2010-01-01

Increased farm salmon production has heightened concerns about the association between disease on farm and wild fish. The controversy is particularly evident in the Broughton Archipelago of Western Canada, where a high prevalence of sea lice (ectoparasitic copepods) was first reported on juvenile wild pink salmon (Oncorhynchus gorbuscha) in 2001. Exposure to sea lice from farmed Atlantic salmon (Salmo salar) was thought to be the cause of the 97% population decline before these fish returned to spawn in 2002, although no diagnostic investigation was done to rule out other causes of mortality. To address the concern that sea lice from fish farms would cause population extinction of wild salmon, we analyzed 10–20 y of fish farm data and 60 y of pink salmon data. We show that the number of pink salmon returning to spawn in the fall predicts the number of female sea lice on farm fish the next spring, which, in turn, accounts for 98% of the annual variability in the prevalence of sea lice on outmigrating wild juvenile salmon. However, productivity of wild salmon is not negatively associated with either farm lice numbers or farm fish production, and all published field and laboratory data support the conclusion that something other than sea lice caused the population decline in 2002. We conclude that separating farm salmon from wild salmon—proposed through coordinated fallowing or closed containment—will not increase wild salmon productivity and that medical analysis can improve our understanding of complex issues related to aquaculture sustainability. PMID:21149706

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.

Ecotoxicology of mercury in fish and wildlife: Recent advances

USGS Publications Warehouse

Scheuhammer, Anton M.; Basu, Niladri; Evers, David C.; Heinz, Gary H.; Sandheinrich, Mark B.; Bank, Michael S.; edited by Bank, Michael S.; Bank, Michael S.

2012-01-01

A number of recent studies have documented subtle, yet potentially important effects of mercury on behavior, neurochemistry, and endocrine function in fish and wildlife at currently realistic levels of environmental exposure. Current levels of environmental methylmercury exposure are sufficient to cause significant biological impairment, both in individuals and in whole populations, in some ecosystems. Future toxicological studies on fish and wildlife will focus on linking biomarkers of methylmercury exposure and associated oxidative stress to effects on reproduction and population change; determining the genetic basis for mercury-related neurotoxic and other biological changes; determining the genetic basis for species differences in sensitivity to methylmercury; and linking toxic effects of methylmercury in individual animals to population-level changes.

A Multiple Watershed Approach to Assessing the Effects of Habitat Restoration Actions on Anadromous and Resident Fish Populations, Technical Report 2003-2004.

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

Marmorek, David

2004-03-01

Habitat protection and restoration is a cornerstone of current strategies to restore ecosystems, recover endangered fish species, and rebuild fish stocks within the Columbia River Basin. Strategies featuring habitat restoration include the 2000 Biological Opinion on operation of the Federal Columbia River Power System (FCRPS BiOp) developed by the National Marine Fisheries Service (NMFS), the 2000 Biological Opinion on Bull Trout developed by the US Fish and Wildlife Service (USFWS), and Sub-Basin Plans developed under the Fish and Wildlife Program of the Northwest Power and Conservation Council (NWPCC). There is however little quantitative information about the effectiveness of different habitatmore » restoration techniques. Such information is crucial for helping scientists and program managers allocate limited funds towards the greatest benefits for fish populations. Therefore, it is critical to systematically test the hypotheses underlying habitat restoration actions for both anadromous and resident fish populations. This pilot project was developed through a proposal to the Innovative Projects fund of the NWPCC (ESSA 2002). It was funded by the Bonneville Power Administration (BPA) following reviews by the Independent Scientific Review Panel (ISRP 2002), the Columbia Basin Fish and Wildlife Authority (CBFWA 2002), the NWPCC and BPA. The study was designed to respond directly to the above described needs for information on the effectiveness of habitat restoration actions, including legal measures specified in the 2000 FCRPS BiOp (RPA 183, pg. 9-133, NMFS 2000). Due to the urgency of addressing these measures, the timeline of the project was accelerated from a duration of 18 months to 14 months. The purpose of this pilot project was to explore methods for evaluating past habitat restoration actions and their effects on fish populations. By doing so, the project will provide a foundation of retrospective analyses, on which to build prospective, multi-watershed designs for future habitat restoration actions. Such designs are being developed concurrently with this project by several other groups in the Columbia Basin (RME Workgroup 2003, NMFS 2003, Hillman and Paulsen 2002, Hillman 2003). By addressing questions about habitat restoration and monitoring (in coordination with other related efforts), we hope that this project will catalyze a shift in the Basin's paradigm of habitat restoration, moving from implementation of individual watershed projects towards rigorously designed and monitored, multiwatershed, adaptive management experiments. The project involved three phases of work, which were closely integrated with various related and ongoing efforts in the region: (1) Scoping - We met with a Core Group of habitat experts and managers to scope out a set of testable habitat restoration hypotheses, identify candidate watersheds and recommend participants for a data evaluation workshop. (2) Data Assembly - We contacted over 80 scientists and managers to help evaluate the suitability of each candidate watershed's historical data for assessing the effectiveness of past restoration actions. We eventually settled on the Yakima, Wenatchee, Clearwater, and Salmon subbasins, and began gathering relevant data for these watersheds at a workshop with habitat experts and managers. Data assembly continued for several months after the workshop. (3) Data Analysis and Synthesis - We explored statistical approaches towards retrospectively analyzing the effects of restoration 'treatments' at nested spatial scales across multiple watersheds (Chapters 2-5 of this report). These analyses provided a foundation for identifying existing constraints to testing restoration hypotheses, and opportunities to overcome these constraints through improved experimental designs, monitoring protocols and project selection strategies (Chapters 6 and 7 of this report). Finally, we developed a set of recommendations to improve the design, implementation, and monitoring of prospective habitat restoration programs in the Columbia River Basin (Chapter 8).« less

The structuring process of the macroparasite community of an experimental population of cichlasoma urophthalmus through time

PubMed

Vidal-Martinez; Kennedy; Aguirre-Macedo

1998-09-01

The structuring process of the macroparasite community of caged Cichlasoma urophthalmus was studied over time using sentinel fish. Three thousand uninfected cichlids were stocked in floating cages introduced into a quarry in which a wild population of the same species was present. Caged and wild cichlids were sampled monthly over 6 and 7 months, respectively. Seventeen macroparasite species were found in the wild C. urophthalmus population, ten of which were detected in the caged population after 6 months. Early infections were by those species that were more frequent and abundant in the wild population, while helminths with a low prevalence and abundance in the wild appeared later in the caged fish population. The results suggested that the structuring process of the macroparasite community of caged C. urophthalmus followed a predictable pattern, in which those species that were most frequent and abundant in the wild were the first to establish in sentinel fish.

Aquatic biology in Nederlo Creek, southwestern Wisconsin

USGS Publications Warehouse

Kammerer, Phil A.; Lidwin, R.A.; Mason, J.W.; Narf, R.P.

1982-01-01

The aquatic community is diverse and reasonably stable with little indication of environmental disturbance. Aquatic macrophyte population (dominated by Ranunculus aquatilis L., Veronica catenata Penn., and Nasturtium offlcinale) varies little from spring to fall. Periphytic and planktonic algae are predominantly diatoms, with the genus Achnanthes dominating both communities. Most genera of planktonic algae originate in the periphyton, but some true planktonic algae were identified. The benthic invertebrate population is dominated by Trichoptera and is a major food source for trout and forage fish. Biotic index values calculated from benthic invertebrate data indicate that water quality is very good to excellent. The trout population is low and represents only a small part of the total fish population both in biomass and numbers. Brown trout are usually stocked annually in the spring to enhance sport fishing, but by fall most trout are wild. The major environmental factors limiting trout population seem to be insufficient cover, insufficient pool depth and volume, and small spawning areas. The wild trout population is highly dependent on spawning success the previous fall.

Evaluation of the effects of the Morgantown SES cooling system on spawning and nursery areas of representative important species. Final report

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

Polgar, T.T.; Summers, J.K.; Haire, M.S.

1979-10-01

Power plant cooling system entrainment and plume entrainment may reduce the sizes of fish, benthic and other populations through the destruction of early life stages. This document has been prepared to estimate the potential effects and impacts of entrainment by the Morgantown (PEPCO) and Possum Point (VEPCO) steam electric generating stations. Maryland water quality regulation requires the determination of entrainment effects on spawning and nursery areas of consequence for the Representative Important Species (RIS) designated within the regulation. The purpose of this evaluation is to provide information for regulatory decisions regarding the need for alternative cooling modes at existing facilities.more » Caclulation schemes are presented to estimate the individual and cumulative entrainment effects due to the operations of both the Morgantown and Possum Point facilities. Potential adult population losses due to the entrainment of early life stages were estimated for 24 RIS populations.« less

Reef-fish larval dispersal patterns validate no-take marine reserve network connectivity that links human communities

NASA Astrophysics Data System (ADS)

Abesamis, Rene A.; Saenz-Agudelo, Pablo; Berumen, Michael L.; Bode, Michael; Jadloc, Claro Renato L.; Solera, Leilani A.; Villanoy, Cesar L.; Bernardo, Lawrence Patrick C.; Alcala, Angel C.; Russ, Garry R.

2017-09-01

Networks of no-take marine reserves (NTMRs) are a widely advocated strategy for managing coral reefs. However, uncertainty about the strength of population connectivity between individual reefs and NTMRs through larval dispersal remains a major obstacle to effective network design. In this study, larval dispersal among NTMRs and fishing grounds in the Philippines was inferred by conducting genetic parentage analysis on a coral-reef fish ( Chaetodon vagabundus). Adult and juvenile fish were sampled intensively in an area encompassing approximately 90 km of coastline. Thirty-seven true parent-offspring pairs were accepted after screening 1978 juveniles against 1387 adults. The data showed all types of dispersal connections that may occur in NTMR networks, with assignments suggesting connectivity among NTMRs and fishing grounds ( n = 35) far outnumbering those indicating self-recruitment ( n = 2). Critically, half (51%) of the inferred occurrences of larval dispersal linked reefs managed by separate, independent municipalities and constituent villages, emphasising the need for nested collaborative management arrangements across management units to sustain NTMR networks. Larval dispersal appeared to be influenced by wind-driven seasonal reversals in the direction of surface currents. The best-fit larval dispersal kernel estimated from the parentage data predicted that 50% of larvae originating from a population would attempt to settle within 33 km, and 95% within 83 km. Mean larval dispersal distance was estimated to be 36.5 km. These results suggest that creating a network of closely spaced (less than a few tens of km apart) NTMRs can enhance recruitment for protected and fished populations throughout the NTMR network. The findings underscore major challenges for regional coral-reef management initiatives that must be addressed with priority: (1) strengthening management of NTMR networks across political or customary boundaries; and (2) achieving adequate population connectivity via larval dispersal to sustain reef-fish populations within these networks.

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.

Longitudinal patterns in flathead catfish relative abundance and length at age within a large river: Effects of an urban gradient

USGS Publications Warehouse

Paukert, C.P.; Makinster, A.S.

2009-01-01

We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005-2006 to collect fish. Relative abundance of age 1 fish (???200mm), subadult (>200-400mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h-1, mean length at age 1 was 165 (range: 128-195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293-419mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = -0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons Ltd.

Tagging methods for estimating population size and mortality rates of inland striped bass populations

USGS Publications Warehouse

Hightower, Joseph E.; Pollock, Kenneth H.

2013-01-01

Striped bass Morone saxatilis in inland reservoirs play an important role ecologically and in supporting recreational fishing. To manage these populations, biologists need information about abundance and mortality. Abundance estimates can be used to assess the effectiveness of stocking programs that maintain most reservoir striped bass populations. Mortality estimates can indicate the relative impact of fishing versus natural mortality and the need for harvest regulation. The purpose of this chapter is to evaluate tagging studies as a way of obtaining information about abundance and mortality. These approaches can be grouped into three broad categories: tag recapture, tag return, and telemetry. Tag-recapture methods are typically used to estimate population size and other demographic parameters but are often difficult to apply in large systems. A fishing tournament can be an effective way of generating tagging or recapture effort in large systems, compared to using research sampling only. Tag-return methods that rely on angler harvest and catch and release can be used to estimate fishing (F) and natural (M) mortality rates and are a practical approach in large reservoirs. The key to success in tag-return studies is to build in auxiliary studies to estimate short-term tagging mortality, short- and longterm tag loss, reporting rate, and mortality associated with catch and release. F and M can also be estimated using telemetry tags. Advantages of this approach are that angler nonreporting does not bias estimates and fish with transmitters provide useful ecological data. Cost can be a disadvantage of telemetry studies; thus, combining telemetry tags with conventional tag returns in an integrated analysis is often the optimal approach. In summary, tagging methods can be a powerful tool for assessing the effectiveness of inland striped bass stocking programs and the relative impact of fishing versus natural mortality

Blue Growth: the 2014 FAO State of the World Fisheries and Aquaculture

USGS Publications Warehouse

Moffitt, Christine M.; Cajas-Cano, Lubia

2014-01-01

The latest United Nations Food and Agriculture Organization report (FAO 2014) addresses the prospect of feeding a human population set to rise to 9.6 billion by 2050. Aquaculture products now provide approximately one-half of all food fish consumed, and fish also provide important food security and economic growth. In the FAO analyses, food fish included finfish, crustaceans, mollusks, amphibians, freshwater turtles, and other aquatic animals (such as sea cucumbers, sea urchins, sea squirts, and edible jellyfish) produced for human consumption. At the present time, food fish provides the world population of nearly 7.3 billion people with an average of one-fifth of total animal protein intake.