USGS fish disease research is focused on developing advanced tools for rapid disease detection and control. USGS scientists are improving our understanding of the factors controlling the epidemiology of aquatic animal diseases and the impact of disease on wild fish populations. Our scientists are also investigating the effects of warming waters, drought, and invasive species on fish disease dynamics.
Wild Fish Disease Research
Wild Fish Disease Research
Chinook Salmon (Oncorhynchus tshawytscha)
Species Studied - Chinook Salmon (Oncorhynchus tshawytscha)
Fish Health
Fish are an important component of marine ecosystems, but relatively little is known of their health, in part because sick and dying fish are difficult to detect.
Explore our science using the data below.
Survival and viral load of chinook salmon, sockeye salmon, and steelhead trout exposed to 4 genogroups of infectious hematopoietic necrosis virus (IHNV)
Theory of the evolution of pathogen specialization suggests that a specialist pathogen gains high fitness in one host, but this comes with fitness loss in other hosts. By contrast, a generalist pathogen does not achieve high fitness in any host, but gains ecological fitness by exploiting different hosts, and has higher fitness than specialists in non-specialized hosts. As a result, specialist path
Analytical and diagnostic validation of a molecular test to detect and discriminate IHNV genogroups U and M
Infectious hematopoietic necrosis virus (IHNV) is an acute pathogen of salmonids in North America, Europe and Asia that is phylogenetically classified into five major virus genogroups (U, M, L, E and J). The geographic range of the U and M genogroup isolates overlap in the North American Columbia River Basin and Washington Coast region, where these genogroups pose different risks depending on the
Spatial and temporal survey of waterborne myxozoan parasites in the Lake Sammamish watershed, Washington, from 2019 - 2021
There is a fundamental knowledge gap on the distribution, prevalence, intensity, and ecology of salmonid myxozoan parasites in the Lake Sammamish watershed, Washington. To address this knowledge gap, we tested water samples for Ceratonova shasta, Parvicapsula minibicornis and Tetracapsuloides bryosalmonae DNA from 84 sites distributed throughout the Lake Sammamish watershed in fall 2019 and 74 sit
Comparative Virulence of Spring Viremia of Carp Virus (SVCV) Genotypes in Two Koi Varieties
Spring viremia of carp virus (SVCV, species Carp sprivivirus), is considered one of the most lethal freshwater pathogens of cyprinid fish. Common carp Cyprinus carpio L. and koi C. carpio koi are the most susceptible host fish species. The virus was formally described in the 1960's after outbreaks occurred in carp species on the European continent, but there has been a global expansion of SVCV pri
Survival, viral load and neutralizing antibodies in steelhead trout and cell cultures exposed to infectious hematopoietic necrosis virus (IHNV) at 3 temperatures
Environmental variation has important effects on host-pathogen interactions, affecting large-scale ecological processes such as the severity and frequency of epidemics. However, less is known about how the environment modulates viral fitness traits and within host infection processes. Viral genetic variation, fish host immune response and environmental parameters such as temperature have been repo
Data from 2018 Experiment on Effects of Temperature on Survival and Growth of Juvenile Lost River Suckers (Deltistes luxatus) naturally exposed to Ichthyobodo spp
Data included in this data set are for an experiment conducted in 2018. Data were collected on survival, growth, food consumption, and Ichthyobodo copy numbers of Lost River suckers exposed to five different temperature groups. There are five levels of data. Temperature data contains 1,178 records and the data file is 35 KB, survival data contains 150 records and the data file is 3 KB, food consum
Laboratory exposure of Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch) and rainbow trout (O. mykiss) to a Pacific Canadian strain of piscine orthoreovirus genotype one (PRV-1)
Piscine orthoreovirus genotype one (PRV-1) is the causative agent of heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar L.). The virus has also been found in Pacific salmonids in western North America, raising concerns about the risk to native salmon and trout. Here, we report the results of laboratory challenges using juvenile Chinook salmon, coho salmon, and rai
Data to Support Efficacy Studies of Injectable Tulathromycin for Reduction of Vertical Transmission of Renibacterium salmoninarum in Spring Chinook Salmon (Oncorhynchus tshawytscha)
Bacterial kidney disease (BKD) caused by Renibacterium salmoninarum (Rs) occurs nearly worldwide where wild or cultured salmonid fishes are present. Control of BKD is confounded by its two modes of transmission, horizontal (fish-to-fish) and vertical (from female parent to progeny via the eggs). A highly successful BKD control strategy employed in Pacific Northwest hatcheries culturing spring Chin
Influence of urbanization on the health of juvenile salmonids in Pacific Northwest perennial streams
Physical and chemical changes affect the biota within urban streams at varying scales ranging from individual organisms to populations and communities creating complex interactions that present challenges for characterizing and monitoring the impact on species utilizing these freshwater habitats. Salmonids, specifically cutthroat trout (Oncorhynchus clarkii) and coho salmon (Oncorhynchus kisutch),
Final Dataset: Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus (PRV) in Alaska and Washington
Dataset for the publication 'Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus (PRV) in Alaska and Washington'. This research was initiated in conjunction with a systematic, multi-agency surveillance effort in the United States (U.S.) in response to reported findings of infectious salmon ane
Pufferfish mortality data
In 2010, a mass mortality of pufferfish in Hawaii was dominated by Arothron hispidus showing aberrant neurological behaviors. Using pathology, toxinology, and field surveys, we implicated a series of novel, polar, marine toxins as a likely cause of this mass mortality. Our findings are striking in that 1) a marine toxin was associated with a kill of a fish species that is, itself, toxic; 2) we
Recent publications (2020-2022) related to USGS fish disease research are listed below. A complete listing of USGS fish disease publications is available from the button below.
Filter Total Items: 33
Comparative susceptibilities of selected California Chinook salmon and steelhead populations to isolates of L Genogroup Infectious Hematopoietic Necrosis Virus (IHNV)
Salmonid species demonstrate varied susceptibility to the viral pathogen infectious hematopoietic necrosis virus (IHNV). In California conservation hatcheries, juvenile Chinook salmon (Oncorhynchus tshawytscha) have experienced disease outbreaks due to L genogroup IHNV since the 1940s, while indigenous steelhead (anadromous O. mykiss) appear relatively resistant. To characterize factors contributi
Authors
Christin M. Bendorf, Susan C. Yun, Gael Kurath, Ronald P. Hedrick
Variation in within-host replication kinetics among virus genotypes provides evidence of specialist and generalist infection strategies across three salmonid host species
Theory of the evolution of pathogen specialization suggests that a specialist pathogen gains high fitness in one host, but this comes with fitness loss in other hosts. By contrast, a generalist pathogen does not achieve high fitness in any host, but gains ecological fitness by exploiting different hosts, and has higher fitness than specialists in nonspecialized hosts. As a result, specialist patho
Authors
David James Páez, Douglas G. McKenney, Maureen K. Purcell, Kerry A. Naish, Gael Kurath
Evaluation of Francisella orientalis ΔpdpA as a live attenuated vaccine against piscine Francisellosis in Nile tilapia
Francisella orientalis is an important bacterial pathogen of marine and freshwater fish with worldwide distribution. Fish francisellosis is a severe subacute to chronic granulomatous disease, with high mortalities and high infectivity rates in cultured and wild fish. To date, there is no approved vaccine for this disease. In this study, we evaluated the efficacy of a defined F. orientalis pathogen
Authors
Fernanda de Alexandre Sebastião, John Hansen, Esteban Soto
Genetics reveal long-distance virus transmission links in Pacific salmon
In the coastal region of Washington State, a major pathogen emergence event occurred between 2007 and 2011 in which steelhead trout (Oncorhynchus mykiss) experienced a high incidence of infection and disease outbreaks due to the rhabdovirus infectious hematopoietic necrosis virus (IHNV). Genetic typing showed that the introduced viruses were in the steelhead-specific MD subgroup of IHNV and indica
Authors
Rachel Breyta, William N. Batts, Gael Kurath
Comparative virulence of spring viremia of carp virus (SVCV) genotypes in two koi varieties
Spring viremia of carp virus (SVCV), is a lethal freshwater pathogen of cyprinid fish, and Cyprinus carpio koi is a primary host species. The virus was initially described in the 1960s after outbreaks occurred in Europe, but a global expansion of SVCV has been ongoing since the late 1990s. Genetic typing of SVCV isolates separates them into 4 genotypes that are correlated with geographic origin: I
Authors
Eveline J. Emmenegger, Emma K. Bueren, Peng Jia, Noble Hendrix, Hong Liu
A novel approach for directly incorporating disease into fish stock assessment: A case study with seroprevalence data
When estimating mortality from disease with fish population models, common disease surveillance data such as infection prevalence are not always informative, especially for fast-acting diseases that may go unobserved in infrequently sampled populations. In these cases, seroprevalence — the proportion of fish with measurable antibody levels in their blood — may be more informative. In cases of life
Authors
John T. Trochta, Maya Groner, Paul Hershberger, Trevor A. Branch
Effects of stocking density on stress response and susceptibility to infectious hematopoietic necrosis virus in rainbow trout
The goals of this study were to examine the effect of stocking density on the stress response and disease susceptibility in juvenile rainbow trout (Oncorhynchus mykiss). Fish were sorted into one of 2 stocking densities (high density "HD", 20-40 kg/m3) or (low density, "LD", 4-8 kg/m3) and 3 stress indices (cortisol levels in serum and water, and neutrophil: lymphocyte (N:L) ratios from blood smea
Authors
Jenna J Klug, Piper M Treuting, George E. Sanders, James Winton, Gael Kurath
Development of a multiplex fluorescence in situ hybridization assay to identify coinfections in young-of-the-year smallmouth bass
Histopathological assessments of young-of-the-year (age-0) Smallmouth Bass Micropterus dolomieu in the Susquehanna River drainage identified a high prevalence of the myxozoan Myxobolus inornatus. This myxozoan infects the connective tissue of the muscle below the skin but is sometimes observed in the esophagus and buccal cavity. In some instances, shallow infections cause breaks in the skin, which
Authors
Heather L. Walsh, Vicki S. Blazer, Patricia M. Mazik
miR133b microinjection during early development targets transcripts of sardiomyocyte ion channels and induces oil-like cardiotoxicity in zebrafish (Danio rerio) embryos
Previous studies have shown that altered expression of a family of small noncoding RNAs (microRNAs, or miRs) regulates the expression of downstream mRNAs and is associated with diseases and developmental disorders. miR133b is highly expressed in mammalian cardiac and skeletal muscle, and aberrant expression is associated with cardiac disorders and electrophysiological changes in cardiomyocytes. Si
Authors
Justin Blaine Greer, Jason T. Magnuson, Victoria McGruer, Le Qian, Subham Dasgupta, David C. Volz, Daniel Schlenk
Targeted and non-targeted analysis of young-of-year smallmouth bass using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry
Smallmouth bass in the Susquehanna River Basin, Chesapeake Bay Watershed, USA, have been exhibiting clinical signs of disease and reproductive endocrine disruption (e.g., intersex, male plasma vitellogenin) for over fifteen years. Previous histological and targeted chemical analyses have identified infectious agents and pollutants in fish tissues including organic contaminants, mercury, and perflu
Authors
Paige Teehan, Megan K. Schall, Vicki S. Blazer, Frank L Dorman
Herring Disease Program - Annual Project Report 2012011-E, February 1, 2010-January 31, 2021
We will investigate fish health factors that may be contributing to the failed recovery of Pacific herring populations in Prince William Sound. Field samples will provide infection and disease prevalence data from Prince William Sound and Sitka Sound to inform the age structured assessment (ASA) model, serological data will indicate the prior exposure history and future susceptibility of herring t
Authors
Paul Hershberger, Maureen K. Purcell
Perfluoroalkyl substances in plasma of smallmouth bass from the Chesapeake Bay Watershed
Smallmouth bass Micropterus dolomieu is an economically important sportfish and within the Chesapeake Bay watershed has experienced a high prevalence of external lesions, infectious disease, mortality events, reproductive endocrine disruption and population declines. To date, no clear or consistent associations with contaminants measured in fish tissue or surface water have been found. Therefore,
Authors
Vicki S. Blazer, Stephanie Gordon, Heather L. Walsh, Cheyenne R. Smith
- Overview
USGS fish disease research is focused on developing advanced tools for rapid disease detection and control. USGS scientists are improving our understanding of the factors controlling the epidemiology of aquatic animal diseases and the impact of disease on wild fish populations. Our scientists are also investigating the effects of warming waters, drought, and invasive species on fish disease dynamics.
Wild Fish Disease ResearchChinook Salmon (Oncorhynchus tshawytscha)
Species Studied - Chinook Salmon (Oncorhynchus tshawytscha)Fish Health
Fish are an important component of marine ecosystems, but relatively little is known of their health, in part because sick and dying fish are difficult to detect. - Data
Explore our science using the data below.
Survival and viral load of chinook salmon, sockeye salmon, and steelhead trout exposed to 4 genogroups of infectious hematopoietic necrosis virus (IHNV)
Theory of the evolution of pathogen specialization suggests that a specialist pathogen gains high fitness in one host, but this comes with fitness loss in other hosts. By contrast, a generalist pathogen does not achieve high fitness in any host, but gains ecological fitness by exploiting different hosts, and has higher fitness than specialists in non-specialized hosts. As a result, specialist pathAnalytical and diagnostic validation of a molecular test to detect and discriminate IHNV genogroups U and M
Infectious hematopoietic necrosis virus (IHNV) is an acute pathogen of salmonids in North America, Europe and Asia that is phylogenetically classified into five major virus genogroups (U, M, L, E and J). The geographic range of the U and M genogroup isolates overlap in the North American Columbia River Basin and Washington Coast region, where these genogroups pose different risks depending on theSpatial and temporal survey of waterborne myxozoan parasites in the Lake Sammamish watershed, Washington, from 2019 - 2021
There is a fundamental knowledge gap on the distribution, prevalence, intensity, and ecology of salmonid myxozoan parasites in the Lake Sammamish watershed, Washington. To address this knowledge gap, we tested water samples for Ceratonova shasta, Parvicapsula minibicornis and Tetracapsuloides bryosalmonae DNA from 84 sites distributed throughout the Lake Sammamish watershed in fall 2019 and 74 sitComparative Virulence of Spring Viremia of Carp Virus (SVCV) Genotypes in Two Koi Varieties
Spring viremia of carp virus (SVCV, species Carp sprivivirus), is considered one of the most lethal freshwater pathogens of cyprinid fish. Common carp Cyprinus carpio L. and koi C. carpio koi are the most susceptible host fish species. The virus was formally described in the 1960's after outbreaks occurred in carp species on the European continent, but there has been a global expansion of SVCV priSurvival, viral load and neutralizing antibodies in steelhead trout and cell cultures exposed to infectious hematopoietic necrosis virus (IHNV) at 3 temperatures
Environmental variation has important effects on host-pathogen interactions, affecting large-scale ecological processes such as the severity and frequency of epidemics. However, less is known about how the environment modulates viral fitness traits and within host infection processes. Viral genetic variation, fish host immune response and environmental parameters such as temperature have been repoData from 2018 Experiment on Effects of Temperature on Survival and Growth of Juvenile Lost River Suckers (Deltistes luxatus) naturally exposed to Ichthyobodo spp
Data included in this data set are for an experiment conducted in 2018. Data were collected on survival, growth, food consumption, and Ichthyobodo copy numbers of Lost River suckers exposed to five different temperature groups. There are five levels of data. Temperature data contains 1,178 records and the data file is 35 KB, survival data contains 150 records and the data file is 3 KB, food consumLaboratory exposure of Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch) and rainbow trout (O. mykiss) to a Pacific Canadian strain of piscine orthoreovirus genotype one (PRV-1)
Piscine orthoreovirus genotype one (PRV-1) is the causative agent of heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (Salmo salar L.). The virus has also been found in Pacific salmonids in western North America, raising concerns about the risk to native salmon and trout. Here, we report the results of laboratory challenges using juvenile Chinook salmon, coho salmon, and raiData to Support Efficacy Studies of Injectable Tulathromycin for Reduction of Vertical Transmission of Renibacterium salmoninarum in Spring Chinook Salmon (Oncorhynchus tshawytscha)
Bacterial kidney disease (BKD) caused by Renibacterium salmoninarum (Rs) occurs nearly worldwide where wild or cultured salmonid fishes are present. Control of BKD is confounded by its two modes of transmission, horizontal (fish-to-fish) and vertical (from female parent to progeny via the eggs). A highly successful BKD control strategy employed in Pacific Northwest hatcheries culturing spring ChinInfluence of urbanization on the health of juvenile salmonids in Pacific Northwest perennial streams
Physical and chemical changes affect the biota within urban streams at varying scales ranging from individual organisms to populations and communities creating complex interactions that present challenges for characterizing and monitoring the impact on species utilizing these freshwater habitats. Salmonids, specifically cutthroat trout (Oncorhynchus clarkii) and coho salmon (Oncorhynchus kisutch),Final Dataset: Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus (PRV) in Alaska and Washington
Dataset for the publication 'Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus (PRV) in Alaska and Washington'. This research was initiated in conjunction with a systematic, multi-agency surveillance effort in the United States (U.S.) in response to reported findings of infectious salmon anePufferfish mortality data
In 2010, a mass mortality of pufferfish in Hawaii was dominated by Arothron hispidus showing aberrant neurological behaviors. Using pathology, toxinology, and field surveys, we implicated a series of novel, polar, marine toxins as a likely cause of this mass mortality. Our findings are striking in that 1) a marine toxin was associated with a kill of a fish species that is, itself, toxic; 2) we - Publications
Recent publications (2020-2022) related to USGS fish disease research are listed below. A complete listing of USGS fish disease publications is available from the button below.
Filter Total Items: 33Comparative susceptibilities of selected California Chinook salmon and steelhead populations to isolates of L Genogroup Infectious Hematopoietic Necrosis Virus (IHNV)
Salmonid species demonstrate varied susceptibility to the viral pathogen infectious hematopoietic necrosis virus (IHNV). In California conservation hatcheries, juvenile Chinook salmon (Oncorhynchus tshawytscha) have experienced disease outbreaks due to L genogroup IHNV since the 1940s, while indigenous steelhead (anadromous O. mykiss) appear relatively resistant. To characterize factors contributiAuthorsChristin M. Bendorf, Susan C. Yun, Gael Kurath, Ronald P. HedrickVariation in within-host replication kinetics among virus genotypes provides evidence of specialist and generalist infection strategies across three salmonid host species
Theory of the evolution of pathogen specialization suggests that a specialist pathogen gains high fitness in one host, but this comes with fitness loss in other hosts. By contrast, a generalist pathogen does not achieve high fitness in any host, but gains ecological fitness by exploiting different hosts, and has higher fitness than specialists in nonspecialized hosts. As a result, specialist pathoAuthorsDavid James Páez, Douglas G. McKenney, Maureen K. Purcell, Kerry A. Naish, Gael KurathEvaluation of Francisella orientalis ΔpdpA as a live attenuated vaccine against piscine Francisellosis in Nile tilapia
Francisella orientalis is an important bacterial pathogen of marine and freshwater fish with worldwide distribution. Fish francisellosis is a severe subacute to chronic granulomatous disease, with high mortalities and high infectivity rates in cultured and wild fish. To date, there is no approved vaccine for this disease. In this study, we evaluated the efficacy of a defined F. orientalis pathogenAuthorsFernanda de Alexandre Sebastião, John Hansen, Esteban SotoGenetics reveal long-distance virus transmission links in Pacific salmon
In the coastal region of Washington State, a major pathogen emergence event occurred between 2007 and 2011 in which steelhead trout (Oncorhynchus mykiss) experienced a high incidence of infection and disease outbreaks due to the rhabdovirus infectious hematopoietic necrosis virus (IHNV). Genetic typing showed that the introduced viruses were in the steelhead-specific MD subgroup of IHNV and indicaAuthorsRachel Breyta, William N. Batts, Gael KurathComparative virulence of spring viremia of carp virus (SVCV) genotypes in two koi varieties
Spring viremia of carp virus (SVCV), is a lethal freshwater pathogen of cyprinid fish, and Cyprinus carpio koi is a primary host species. The virus was initially described in the 1960s after outbreaks occurred in Europe, but a global expansion of SVCV has been ongoing since the late 1990s. Genetic typing of SVCV isolates separates them into 4 genotypes that are correlated with geographic origin: IAuthorsEveline J. Emmenegger, Emma K. Bueren, Peng Jia, Noble Hendrix, Hong LiuA novel approach for directly incorporating disease into fish stock assessment: A case study with seroprevalence data
When estimating mortality from disease with fish population models, common disease surveillance data such as infection prevalence are not always informative, especially for fast-acting diseases that may go unobserved in infrequently sampled populations. In these cases, seroprevalence — the proportion of fish with measurable antibody levels in their blood — may be more informative. In cases of lifeAuthorsJohn T. Trochta, Maya Groner, Paul Hershberger, Trevor A. BranchEffects of stocking density on stress response and susceptibility to infectious hematopoietic necrosis virus in rainbow trout
The goals of this study were to examine the effect of stocking density on the stress response and disease susceptibility in juvenile rainbow trout (Oncorhynchus mykiss). Fish were sorted into one of 2 stocking densities (high density "HD", 20-40 kg/m3) or (low density, "LD", 4-8 kg/m3) and 3 stress indices (cortisol levels in serum and water, and neutrophil: lymphocyte (N:L) ratios from blood smeaAuthorsJenna J Klug, Piper M Treuting, George E. Sanders, James Winton, Gael KurathDevelopment of a multiplex fluorescence in situ hybridization assay to identify coinfections in young-of-the-year smallmouth bass
Histopathological assessments of young-of-the-year (age-0) Smallmouth Bass Micropterus dolomieu in the Susquehanna River drainage identified a high prevalence of the myxozoan Myxobolus inornatus. This myxozoan infects the connective tissue of the muscle below the skin but is sometimes observed in the esophagus and buccal cavity. In some instances, shallow infections cause breaks in the skin, whichAuthorsHeather L. Walsh, Vicki S. Blazer, Patricia M. MazikmiR133b microinjection during early development targets transcripts of sardiomyocyte ion channels and induces oil-like cardiotoxicity in zebrafish (Danio rerio) embryos
Previous studies have shown that altered expression of a family of small noncoding RNAs (microRNAs, or miRs) regulates the expression of downstream mRNAs and is associated with diseases and developmental disorders. miR133b is highly expressed in mammalian cardiac and skeletal muscle, and aberrant expression is associated with cardiac disorders and electrophysiological changes in cardiomyocytes. SiAuthorsJustin Blaine Greer, Jason T. Magnuson, Victoria McGruer, Le Qian, Subham Dasgupta, David C. Volz, Daniel SchlenkTargeted and non-targeted analysis of young-of-year smallmouth bass using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry
Smallmouth bass in the Susquehanna River Basin, Chesapeake Bay Watershed, USA, have been exhibiting clinical signs of disease and reproductive endocrine disruption (e.g., intersex, male plasma vitellogenin) for over fifteen years. Previous histological and targeted chemical analyses have identified infectious agents and pollutants in fish tissues including organic contaminants, mercury, and perfluAuthorsPaige Teehan, Megan K. Schall, Vicki S. Blazer, Frank L DormanHerring Disease Program - Annual Project Report 2012011-E, February 1, 2010-January 31, 2021
We will investigate fish health factors that may be contributing to the failed recovery of Pacific herring populations in Prince William Sound. Field samples will provide infection and disease prevalence data from Prince William Sound and Sitka Sound to inform the age structured assessment (ASA) model, serological data will indicate the prior exposure history and future susceptibility of herring tAuthorsPaul Hershberger, Maureen K. PurcellPerfluoroalkyl substances in plasma of smallmouth bass from the Chesapeake Bay Watershed
Smallmouth bass Micropterus dolomieu is an economically important sportfish and within the Chesapeake Bay watershed has experienced a high prevalence of external lesions, infectious disease, mortality events, reproductive endocrine disruption and population declines. To date, no clear or consistent associations with contaminants measured in fish tissue or surface water have been found. Therefore,AuthorsVicki S. Blazer, Stephanie Gordon, Heather L. Walsh, Cheyenne R. Smith