Skip to main content
U.S. flag

An official website of the United States government

Heather Walsh

Dr. Heather Walsh is a Research Fish Biologist that has been involved in research at the Eastern Ecological Science Center since 2006. 

Dr. Walsh has focused on developing molecular techniques to better understand mechanisms associated with disease in wild fish. To serve this purpose, she has developed her skills in histopathology, in situ hybridization techniques, and laser capture microdissection. The use of these techniques has helped to understand disease observed during fish health assessments conducted in the Great Lakes and Chesapeake Bay (including the Susquehanna and Potomac River drainage). Much of her work has focused on fish species used as indicators of environmental contamination, including smallmouth bass, brown bullhead catfish, white suckers, and yellow perch. She also uses PCR, Sanger sequencing, Nanostring technology, and RNA-Seq to help identify parasites or pathogens, for transcript abundance analyses, and de novo transcriptome development. 

Professional Experience

  • 2022-Present: Research Fish Biologist, USGS EESC, Kearneysville, WV

  • 2019-2022: Post-Doc Researcher, USGS EESC, Kearneysville, WV

  • 2006-2019: Biological Science Technician/Contractor USGS EESC, Kearneysville, WV 

Education and Certifications

  • Ph.D., Forest Resource Science Program, Wildlife and Fisheries Management Major, West Virginia University, 2018

  • M.S., Wildlife and Fisheries Management, West Virginia University, Morgantown, WV, 2011

  • B.S., Environmental Studies with a Concentration in Aquatic Science, Shepherd University, Shepherdstown, WV, 2008

  • B.S., Environmental Studies with a Concentration in Aquatic Science, Shepherd University, Shepherdstown, WV, 2008

Affiliations and Memberships*

  • American Fisheries Society, Fish Health Section

  • Northeast Fish Health Committee 

Science and Products

link
Collecting water quality samples from the New River Gorge

A case study of temporal trends in risk factors associated with endocrine disruption in smallmouth bass

Issue The USGS has a long-term research effort that identified endocrine disruption in smallmouth bass (SMB) in the Chesapeake Bay watershed. Endocrine disruption can cause many changes in fish, including intersex characteristics where fish develop characteristics of the other sex, such as immature eggs forming in males. An overview by USGS of endocrine disruption in fish found the condition...
By
Environmental Health Program, Chesapeake Bay Activities, Eastern Ecological Science Center
link

A case study of temporal trends in risk factors associated with endocrine disruption in smallmouth bass

Issue The USGS has a long-term research effort that identified endocrine disruption in smallmouth bass (SMB) in the Chesapeake Bay watershed. Endocrine disruption can cause many changes in fish, including intersex characteristics where fish develop characteristics of the other sex, such as immature eggs forming in males. An overview by USGS of endocrine disruption in fish found the condition...
Learn More
link
Scientist holding a brook trout with gloved hands

Fishing and Hunting Integrated Science Team

The Fishing and Hunting integrated science team focuses on contaminant and pathogen exposures in the environment that could impact the presence and vitality of fish and wildlife populations that drive commercial, recreational and subsistence activities such as hunting and fishing. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
link

Fishing and Hunting Integrated Science Team

The Fishing and Hunting integrated science team focuses on contaminant and pathogen exposures in the environment that could impact the presence and vitality of fish and wildlife populations that drive commercial, recreational and subsistence activities such as hunting and fishing. If actual risks are identified this project will inform how to economically and effectively minimize risk by providing...
Learn More

Immune Function of Wild Smallmouth Bass Collected from Sites within the Chesapeake Bay Watershed, 2016-2021

Adult and young of the year smallmouth bass from the Chesapeake Bay watershed have faced health issues (mortality events, disease by a variety of pathogens, endocrine disruption in male fish, evidence of oxidative damage to tissues, and signs of exposure to chemical contaminants) at multiple sites within the Susquehanna and Potomac River basins. Functional immune assays were added to long-term com
By
Eastern Ecological Science Center

Water Chemistry and Smallmouth Bass Biological Data From the Potomac River, Dargan, Maryland, 2013-2019

Decades of poor reproductive success and young-of-the-year recruitment, in addition to adult mortality, has led to a decline in the smallmouth bass (SMB) population in subwatersheds of the Potomac River. Previous studies have identified numerous biologic and environmental stressors associated with negative effects on SMB health. To better understand the impact of these stressors, the current study
By
Chesapeake Bay Activities, Eastern Ecological Science Center

Biological variables and liver and testes transcript abundance from smallmouth bass sampled in the Lake Erie drainage, Pennsylvania (2016)

In 2016, smallmouth bass were collected from three sites in the Lake Erie drainage in Erie County, Pennsylvania and an out-of-basin site in the Allegheny River drainage in order to assess reproductive health and identify endocrine disruption responses. Pieces of liver and gonad were taken in Z-Fix and RNALater for histology and transcript abundance analysis. A landscape analysis was conducted for
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center

Presence/Absence of Myxobolus inornatus, Aeromonas spp., and Flavobacterium spp. in Young-of-the-Year Smallmouth Bass with Fluorescence In Situ Hybridization

Histopathological assessments of young-of-the-year smallmouth bass (YOY SMB) 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 could increase the
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center

Morphometric, Age, Visible Abnormalities, Skin and Liver Neoplasms, and Stable Isotopes in White Sucker Collected in the St. Louis River and Estuary, Minnesota/Wisconsin, 2011-2015

The dataset provides length, weight, age, observations of visible external abnormalities, liver and skin histopathology and stable isotopes of white sucker captured within the St. Louis river and associated bays.
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center

Morphometric, Age and Concentrations of Perfluoroalkyl Substances in Smallmouth Bass Plasma from Four Sites in the Chesapeake Bay Watershed

Archived plasma from fish health monitoring sites within the Chesapeake Bay watershed was analyzed for 13 perfluoroalkyl compounds. Smallmouth bass were collected from two sites in the Potomac River drainage (Antietam Creek, Maryland and South Branch Potomac, West Virginia) and two in the Susquehanna River drainage (West Branch Mahantango Creek, Pennsylvania and Pine Creek, Pennsylvania). Site and
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Chesapeake Bay Activities, Eastern Ecological Science Center

2004-2010 Chesapeake Bay Smallmouth and Largemouth Bass Estrogenic Biomarker Data

The data was gathered to document the extent and severity of biomarkers of exposure to estrogenic chemicals in smallmouth and largemouth bass. Samples were collected from 2004 through 2010 at sites in five watersheds within the Chesapeake Bay watershed. A total of 281 largemouth bass were collected from the Potomac, Susquehanna, Patuxent and Rappahannock rivers and 1,384 smallmouth bass from the P
By
Ecosystems Mission Area, Contaminant Biology, Chesapeake Bay Activities, Eastern Ecological Science Center

Abundance of 50 transcripts from microdissected liver samples of smallmouth bass

There is an increasing emphasis on effects-based monitoring to document responses associated with exposure to complex mixtures of chemicals, climate change, pathogens, parasites and other environmental stressors in fish populations. For decades aquatic monitoring programs have included the collection of tissues preserved for microscopic pathology. Consequently, formalin-fixed, paraffin-embedded (F
By
Eastern Ecological Science Center
A researcher with a dissected fish.
link
Sunrise of blue and orange hues and clouds illuminated by the rising sun. Clear water reflects the sky and the leafless tree
link
Scientist inserting a needle with a syringe in the caudal vein (located below the spine) of a smallmouth bass
link
Scientist examining the gills of a smallmouth bass for abnormalities such as parasites, erosion, and fraying.
link
The Leetown trout pond on a beautiful, sunny day with blue skies and green foliage all around.
link
Chesapeake Bay Land Use Map and Chart
link
Chart of changes in smallmouth bass
link
Chart of concentrations of three of the most detected pesticides in Dargan, MD
link
Photo of a 45" muskellunge used in a catch and release study on angling mortality during warmer summer conditions.
link
Histology laboratory (prior to renovations) with coverslipping area, file/record keeping center, and embedding center.
link
Scientists working with a fish specimen to assess health and disease in the fish population.
link
Filter Total Items: 33

Assembling the right pieces: Developing an interdisciplinary team to study disease, decline, and recovery of a world-class Smallmouth Bass fishery

Managing and understanding fisheries dynamics are becoming more complex as new and seemingly more complicated environmental factors are identified. Often management requires resources beyond that of any one entity and calls for collaboration among partners with differing priorities and backgrounds to account for the complexity of factors influencing fisheries. We present a collaborative case study
Authors
Megan K. Schall, Geoffrey Smith, Vicki S. Blazer, Heather L. Walsh, Timothy Wertz, Dustin R. Shull, Tyler Wagner
By
Chesapeake Bay Activities, Eastern Ecological Science Center

A multi-level assessment of biological effects associated with mercury concentrations in smallmouth bass, Micropterus dolomieu

Total mercury (THg) was measured in muscle (fillet) and liver tissue of adult smallmouth bass Micropterus dolomieu collected at multiple sites in the Potomac and Susquehanna River drainages within the Chesapeake Bay watershed. Smallmouth bass in these drainages have experienced episodic mortality events, a high prevalence of skin lesions and reproductive endocrine disruption (intersex or testicula
Authors
Vicki S. Blazer, Heather L. Walsh, Adam Sperry, Brenna Raines, James Willacker, Collin Eagles-Smith
By
Ecosystems Mission Area, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Pennsylvania Water Science Center

Evaluating Muskellunge (Esox masquinongy) catch-and-release mortality at elevated summer water temperature

Angling for Muskellunge Esox masquinongy has become widespread and increasingly popular. Management strategies for Muskellunge include high minimum harvest lengths (>1016mm), closed seasons, and catch-and-release regulations. Due to these strategies and angler behaviors, up to 97% of Muskellunge caught are released, and anglers assume these fish survive to be caught again in the future. Previous r
Authors
Ian Taylor Booth, Kyle J. Hartman, Derek P. Crane, Jeff L. Hansbarger, Jordan Weeks, Josh Henesy, Heather L. Walsh, Jeffrey C. Williams
By
Ecosystems Mission Area, Eastern Ecological Science Center

Application of a lipopolysaccharide (LPS)-stimulated mitogenesis assay in smallmouth bass (Micropterus dolomieu) to augment wild fish health studies

The utility of a functional immune assay for smallmouth bass (Micropterus dolomieu) lymphocyte mitogenesis was evaluated. Wild populations in the Potomac River have faced disease and mortality with immunosuppression from exposure to chemical contaminants a suspected component. However, a validated set of immune parameters to screen for immunosuppression in wild fish populations is not available. P
Authors
Cheyenne R. Smith, Christopher A. Ottinger, Heather L. Walsh, Patricia M. Mazik, Vicki S. Blazer
By
Eastern Ecological Science Center

A case study: Temporal trends of environmental stressors and reproductive health of smallmouth bass (Micropterus dolomieu) from a site in the Potomac River Watershed, Maryland, USA

Decades of poor reproductive success and young-of-the-year survival, combined with adult mortality events, have led to a decline in the smallmouth bass (SMB; Micropterus dolomieu) population in sections of the Potomac River. Previous studies have identified numerous biologic and environmental stressors associated with negative effects on SMB health. To better understand the impact of these stresso
Authors
Heather L. Walsh, Stephanie Gordon, Adam J. Sperry, Michael Kashiwagi, John E. Mullican, Vicki S. Blazer
By
Chesapeake Bay Activities, Eastern Ecological Science Center

Potential health effects of contaminant mixtures from point and nonpoint sources on fish and frogs in the New Jersey Pinelands

Aquatic ecosystems convey complex contaminant mixtures from anthropogenic pollution on a global scale. Point (e.g., municipal wastewater) and nonpoint sources (e.g., stormwater runoff) are both drivers of contaminant mixtures in aquatic habitats. The objectives of this study were to identify the contaminant mixtures present in surface waters impacted by both point and nonpoint sources, to determin
Authors
Sara Breitmeyer, Heather L. Walsh, Vicki S. Blazer, John F. Bunnell, Patrick M. Burritt, Jeff Dragon, Michelle Hladik, Paul Bradley, Kristin Romanok, Kelly Smalling
By
Water Resources Mission Area, Eastern Ecological Science Center, California Water Science Center, New Jersey Water Science Center, South Atlantic Water Science Center (SAWSC)

Reproductive health and endocrine disruption in smallmouth bass (Micropterus dolomieu) from the Lake Erie drainage, Pennsylvania, USA

Smallmouth bass Micropterus dolomieu were sampled from three sites within the Lake Erie drainage (Elk Creek, Twentymile Creek, and Misery Bay, an embayment in Presque Isle Bay). Plasma, tissues for histopathological analyses, and liver and testes preserved in RNALater® were sampled from 30 smallmouth bass (of both sexes) at each site. Liver and testes samples were analyzed for transcript abundance
Authors
Heather L. Walsh, Sean D. Rafferty, Stephanie Gordon, Vicki S. Blazer
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center

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
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center

Identification of Aphanomyces invadans, the cause of epizootic ulcerative syndrome, in smallmouth bass (Micropterus dolomieu) from the Cheat River, West Virginia, USA

The oomycete Aphanomyces invadans (Saprolegniales, Oomycetes), the cause of epizootic ulcerative syndrome (EUS), is an OIE (World Organization for Animal Health) reportable pathogen, capable of infecting many fish species worldwide in both freshwater and estuarine environments (Iberahim et al. 2018). Since the discovery of EUS in Japan in 1971 (Egusa and Masuda 1971), it has spread globally and ca
Authors
Heather L. Walsh, Vicki S. Blazer, Patricia M. Mazik
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center

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
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Eastern Ecological Science Center, Chesapeake Bay Activities, Pennsylvania Water Science Center

Assessing native fish restoration potential in Catoctin Mountain Park

Biological conservation is a fundamental purpose of the National Park system, and Catoctin Mountain Park (CATO) supports high-quality habitat for native fishes in the headwaters of the Chesapeake Bay watershed in eastern North America. However, native Blue Ridge sculpin (Cottus caeruleomentum) have been extirpated in Big Hunting Creek above Cunningham Falls in CATO. Prior research indicates that i
Authors
Nathaniel P. Hitt, Karmann G. Kessler, Zachary A. Kelly, Karli M. Rogers, Hannah E. Macmillan, Heather L. Walsh
By
Ecosystems Mission Area, Eastern Ecological Science Center, Chesapeake Bay Activities

Retrospective analysis of estrogenic endocrine disruption and land-use influences in the Chesapeake Bay watershed

The Chesapeake Bay is the largest estuary in the United States and its watershed includes river drainages in six states and the District of Columbia. Sportfishing is of major economic interest, however, the rivers within the watershed provide numerous other ecological, recreational, cultural and economic benefits, as well as serving as a drinking water source for millions of people. Consequently,
Authors
Vicki S. Blazer, Stephanie Gordon, Daniel Jones, Luke R. Iwanowicz, Heather L. Walsh, Adam Sperry, Kelly Smalling
By
Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Chesapeake Bay Activities, Eastern Ecological Science Center, New Jersey Water Science Center

Science and Products

*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government