Paul Hershberger, Ph.D.
Paul Hershberger is the Chief of the Fish Heath Section at the U. S. Geological Survey - Western Fisheries Research Center (Seattle, WA) and the Station Leader at the Marrowstone Marine Field Station (Nordland, WA). He is an Affiliate Professor at the University of Washington – School of Aquatic and Fishery Sciences, and former President of the Fish Health Section - American Fisheries Society.
Paul has the pleasure of leading a team of fish health professionals who are experts in their respective fields of fish virology, immunology, toxicology, histopathology, parasitology, and disease ecology. Specific components of the Fish Health Section focus on:
- the development of immune-related tools for fishes and the impact(s) of environmental stressors (e.g. contaminants, pathogens, temperature) on the fish immune response.
- the use of gene knock outs in zebrafish and other model species to assess pathogen virulence and host immune response mechanisms.
- the evolution of virulence and other phenotypes in fish viruses using landscape-scale genotyping to identify patterns of virus occurrence, transmission, and disease impacts across borad temporal and geographic scales.
- the discovery and identification of new and emerging fish viruses in the Pacific Northwest and throughout North America.
- the integration of novel quantitative techniques to understand stochasticity of pathogen transmission and other mechanisms of basic and applied disease ecology.
- the use of histopathology and electron microscopy to assess pathogen / disease monitoring and research needs in populations of wild and hatchery-raised fishes.
- the effects of environmental contaminants, including PAH’s, PCB’s, and emerging contaminants like PFAS and 6-PPD quinone on fish health, survival, and immunological pathways.
- the range expansion of invasive amphibians and their susceptibility to native and exotic pathogens.
In addition, Paul’s personal research employs a combination of laboratory and field approaches to understand, forecast, and mitigate the impacts of infectious and parasitic diseases on populations of wild marine and anadromous fishes.
Professional Experience
2022 to Present: Fish Health Section Chief, U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA
2003 to Present – Station Leader, U.S. Geological Survey, Western Fisheries Research Center, Marrowstone Marine Field Station, Nordland, WA
2004 to Present – Member of the Affiliate Faculty, School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA
Education and Certifications
Ph.D. Fisheries, School of Aquatic and Fisheries Sciences, University of Washington, Seattle, WA
M.S. Fisheries, School of Aquatic and Fisheries Sciences, University of Washington, Seattle, WA
B.S. Chemistry and Biology, Northland College, Ashland, WI
Science and Products
Release of infectious cells from epidermal ulcers in Ichthyophonus sp.–infected Pacific Herring (Clupea pallasii): Evidence for multiple mechanisms of transmission
Kinetics of viral shedding provide insights into the epidemiology of viral hemorrhagic septicemia in Pacific herring
Chronic and persistent viral hemorrhagic septicemia virus infections in Pacific herring
Amplification and transport of an endemic fish disease by an introduced species
Feasibility of Surgically Implanting Acoustic Tags into Pacific Herring
Prevalence of viral erythrocytic necrosis in Pacific herring and epizootics in Skagit Bay, Puget Sound, Washington.
Differential survival of Ichthyophonus isolates indicates parasite adaptation to its host environment
Potential for cross-contamination of in vitro explant cultures initiated from Ichthyophonus-infected rainbow trout, Oncorhynchus mykiss (Walbaum)
Inactivation of Ichthyophonus spores using sodium hypochlorite and polyvinyl pyrrolidone iodine
Larval Pacific herring, Clupea pallasii (Valenciennes), are highly susceptible to viral haemorrhagic septicaemia and survivors are partially protected after their metamorphosis to juveniles
Differences in Ichthyophonus prevalence and infection severity between upper Yukon River and Tanana River chinook salmon, Oncorhynchus tshawytscha (Walbaum), stocks
Ichthyophonus-induced cardiac damage: a mechanism for reduced swimming stamina in salmonids
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Release of infectious cells from epidermal ulcers in Ichthyophonus sp.–infected Pacific Herring (Clupea pallasii): Evidence for multiple mechanisms of transmission
A common clinical sign of ichthyophoniasis in herring and trout is “sandpaper” skin, a roughening of the epidermis characterized by the appearance of small papules, followed by ulceration and sloughing of the epithelium; early investigators hypothesized that these ulcers might be a means of transmitting the parasite, Ichthyophonus sp., without the necessity of ingesting an infected host. We examinAuthorsPaul K. Hershberger, Jacob L. Gregg, R. M. KocanKinetics of viral shedding provide insights into the epidemiology of viral hemorrhagic septicemia in Pacific herring
Losses from infectious diseases are an important component of natural mortality among marine fish species, but factors controlling the ecology of these diseases and their potential responses to anthropogenic changes are poorly understood. We used viral hemorrhagic septicemia virus (VHSV) and a laboratory stock of Pacific herring Clupea pallasii to investigate the kinetics of viral shedding and itsAuthorsPaul K. Hershberger, Jacob L. Gregg, James R. Winton, Courtney Grady, Rachael CollinsChronic and persistent viral hemorrhagic septicemia virus infections in Pacific herring
Chronic viral hemorrhagic septicemia virus (VHSV) infections were established in a laboratory stock of Pacific herring Clupea pallasii held in a large-volume tank supplied with pathogen-free seawater at temperatures ranging from 6.8 to 11.6°C. The infections were characterized by viral persistence for extended periods and near-background levels of host mortality. Infectious virus was recovered froAuthorsPaul K. Hershberger, Jacob L. Gregg, James R. Winton, Cortney A. Grady, L. TaylorAmplification and transport of an endemic fish disease by an introduced species
The introduction of American shad from the Atlantic to the Pacific coast of North America in the late 1800’s and the subsequent population expansion in the 1980’s resulted in the amplification of Ichthyophonus sp., a Mesomycetozoean parasite of wild marine fishes. Sequence analysis of the ribosomal DNA gene complex (small subunit and internal transcribed spacer regions) and Ichthyophonus epidemiolAuthorsPaul Hershberger, Bjorn Leeuw, Gregg Jacob, Courtney Grady, Kenneth Lujan, Susan Gutenberger, Maureen K. Purcell, James Woodson, James Winton, Michael ParsleyFeasibility of Surgically Implanting Acoustic Tags into Pacific Herring
Internally implanted acoustic tags represent a potentially valuable approach to assessing the seasonal migration and distribution patterns of Pacific herring Clupea palasii. We examined the feasibility of implanting two sizes of dummy acoustic tags (9 mm in diameter × 21 mm long, 1.6 g; and 7 mm in diameter × 18 mm long, 0.7 g) in Pacific herring that had been held in captivity for nearly a year aAuthorsPaul K. Hershberger, Jacob L. Gregg, A.C. Seitz, Brenda L. Norcross, J.C. Payne, A.N. Kagley, B MeloyPrevalence of viral erythrocytic necrosis in Pacific herring and epizootics in Skagit Bay, Puget Sound, Washington.
Epizootics of viral erythrocytic necrosis (VEN) occurred among juvenile Pacific herring Clupea pallasii in Skagit Bay, Puget Sound, Washington, during 2005-2007 and were characterized by high prevalences and intensities of cytoplasmic inclusion bodies within circulating erythrocytes. The prevalence of VEN peaked at 67% during the first epizootic in October 2005 and waned to 0% by August 2006. A seAuthorsP.K. Hershberger, N.E. Elder, C.A. Grady, J.L. Gregg, C.A. Pacheco, C. Greene, C. Rice, T.R. MeyersDifferential survival of Ichthyophonus isolates indicates parasite adaptation to its host environment
In vitro viability of Ichthyophonus spp. spores in seawater and freshwater corresponded with the water type of the host from which the spores were isolated. Among Ichthyophonus spp. spores from both marine and freshwater fish hosts (Pacific herring, Clupea pallasii, and rainbow trout, Oncorhynchus mykiss, respectively), viability was significantly greater (P < 0.05) after incubation in seawater thAuthorsP.K. Hershberger, C.A. Pacheco, J.L. Gregg, M. K. Purcell, S. E. LaPatraPotential for cross-contamination of in vitro explant cultures initiated from Ichthyophonus-infected rainbow trout, Oncorhynchus mykiss (Walbaum)
[No abstract available]AuthorsS. LaPatra, R. Kocan, P. HershbergerInactivation of Ichthyophonus spores using sodium hypochlorite and polyvinyl pyrrolidone iodine
Chlorine and iodine solutions were effective at inactivating Ichthyophonus spores in vitro. Inactivation in sea water increased directly with halogen concentration and exposure duration, with significant differences (P < 0.05) from controls occurring at all chlorine concentrations and exposure durations tested (1.5-13.3 ppm for 1-60 min) and at most iodine concentrations and exposure durations tesAuthorsP.K. Hershberger, C.A. Pacheco, J.L. GreggLarval Pacific herring, Clupea pallasii (Valenciennes), are highly susceptible to viral haemorrhagic septicaemia and survivors are partially protected after their metamorphosis to juveniles
Pacific herring were susceptible to waterborne challenge with viral haemorrhagic septicaemia virus (VHSV) throughout their early life history stages, with significantly greater cumulative mortalities occurring among VHSV-exposed groups of 9-, 44-, 54- and 76-day-old larvae than among respective control groups. Similarly, among 89-day-1-year-old and 1+year old post-metamorphosed juveniles, cumulatiAuthorsP.K. Hershberger, J. Gregg, C. Pacheco, J. Winton, J. Richard, G. TraxlerDifferences in Ichthyophonus prevalence and infection severity between upper Yukon River and Tanana River chinook salmon, Oncorhynchus tshawytscha (Walbaum), stocks
Two genetically distinct populations of chinook salmon, Oncorhynchus tshawytscha (Walbaum), were simultaneously sampled at the confluence of the Yukon and Tanana rivers in 2003. Upper Yukon-Canadian fish had significantly higher infection prevalence as well as more severe infections (higher parasite density in heart tissue) than the lower Yukon-Tanana River fish. Both populations had migrated theAuthorsR. Kocan, P. HershbergerIchthyophonus-induced cardiac damage: a mechanism for reduced swimming stamina in salmonids
Swimming stamina, measured as time-to-fatigue, was reduced by approximately two-thirds in rainbow trout experimentally infected with Ichthyophonus. Intensity of Ichthyophonus infection was most severe in cardiac muscle but multiple organs were infected to a lesser extent. The mean heart weight of infected fish was 40% greater than that of uninfected fish, the result of parasite biomass, infiltratiAuthorsR. Kocan, S. LaPatra, J. Gregg, J. Winton, P. Hershberger - News