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Jacob Gregg

Jacob is a Fish Biologist at the Marrowstone Marine Field Station, Nordland, WA.

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Herring juvenile 103 days post-hatch.

PCB Exposure and Disease Susceptibility

Researchers at that MMFS are experimentally determining the impacts of high PCB body burdens on the immunocompetency and disease susceptibility of Pacific herring.
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Ecosystems Mission Area, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)
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PCB Exposure and Disease Susceptibility

Researchers at that MMFS are experimentally determining the impacts of high PCB body burdens on the immunocompetency and disease susceptibility of Pacific herring.
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Image: Pacific Herring larvae

PAH Exposure and Disease Susceptibility

Researchers at the MMFS are studying the immediate and delayed effects of petroleum hydrocarbon exposures to Pacific herring.
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Ecosystems Mission Area, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)
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PAH Exposure and Disease Susceptibility

Researchers at the MMFS are studying the immediate and delayed effects of petroleum hydrocarbon exposures to Pacific herring.
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Kidney of a steelhead with heavy N. salmincola infection

Effects of Nanophyetus salmincola on the Health and Survival of Puget Sound Steelhead

Low early marine survival rates of Puget Sound steelhead (Oncorhynchus mykiss), the state fish of Washington, have contributed to its dramatic population decline and current listing as a “Threatened Species” under the Endangered Species Act. Determining the cause(s) of this elevated mortality remains a primary objective of the Salish Sea Marine Survival Project, a large US / Canada effort...
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Ecosystems Mission Area, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)
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Effects of Nanophyetus salmincola on the Health and Survival of Puget Sound Steelhead

Low early marine survival rates of Puget Sound steelhead (Oncorhynchus mykiss), the state fish of Washington, have contributed to its dramatic population decline and current listing as a “Threatened Species” under the Endangered Species Act. Determining the cause(s) of this elevated mortality remains a primary objective of the Salish Sea Marine Survival Project, a large US / Canada effort...
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Lingering oil in the sediments of Knight Island

Genomic Mechanisms that Underlie Lack of Recovery of Prince William Sound Herring Following the 1990s Collapse

In the decades following the Exxon Valdez Oil Spill (EVOS), it has become increasingly apparent that oil can be toxic at extremely low concentrations to developing fish embryos including herring, where some toxic phenotypes may be apparent during embryogenesis, but some are delayed until later in life. Therefore, acute and lingering oil may act as an insidious selective force within populations...
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Ecosystems Mission Area, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)
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Genomic Mechanisms that Underlie Lack of Recovery of Prince William Sound Herring Following the 1990s Collapse

In the decades following the Exxon Valdez Oil Spill (EVOS), it has become increasingly apparent that oil can be toxic at extremely low concentrations to developing fish embryos including herring, where some toxic phenotypes may be apparent during embryogenesis, but some are delayed until later in life. Therefore, acute and lingering oil may act as an insidious selective force within populations...
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Oil Tanker in Prince William Sound

Herring Disease Program

Using an approach that involves a combination of field- and laboratory-based studies, we are investigating fish health factors that may be contributing to the failed recovery of Pacific herring populations in Prince William Sound, AK. Field studies are providing infection and disease prevalence data to inform the population models, serological data that indicate the prior exposure history and...
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Ecosystems Mission Area, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)
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Herring Disease Program

Using an approach that involves a combination of field- and laboratory-based studies, we are investigating fish health factors that may be contributing to the failed recovery of Pacific herring populations in Prince William Sound, AK. Field studies are providing infection and disease prevalence data to inform the population models, serological data that indicate the prior exposure history and...
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Caligus Clemensi prevalence and counts on Clupea pallasii from Port Angeles Harbor, WA and from a controlled laboratory experiment conducted at USGS Marrowstone Marine Field Station, WA

We characterized a natural sea louse epizootic of Caligus clemensi and the effects of parasitism on Pacific herring Clupea pallasii in Port Angeles Harbor, WA, USA. Infestation prevalence on newly metamorphosed age0 Pacific herring reached 100% prevalence by mid-August. At this time, the mean louse intensity was 4.6 lice and a positive correlation occurred between louse intensity and Pacific herri
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Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

DNA sequences from Ichthyophonid parasites

Data included are DNA sequences used to identify species boundaries among Ichthyophonus-like parasites. Sequences were generated for three gene regions from each parasite isolate. DNA sequences can be downloaded from GenBank (https://www.ncbi.nlm.nih.gov/) as text or fasta files. Accession numbers for each sequence are included in the data table (.csv file). Data includes 87 sequences (99,383 tota
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Biological Threats and Invasive Species Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)
Image: Pacific Herring larvae
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Image: Pacific Herring Larvae
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Image: Pacific Herring Eggs on Macrophytes
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Image: Pacific Herring School
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Image: Pacific Herring Spawning Event
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Filter Total Items: 40

Characteristics of a sea louse (Caligus clemensi) epizootic in wild Pacific herring (Clupea pallasii)

We characterized a natural sea louse epizootic of Caligus clemensi and the effects of parasitism on Pacific herring Clupea pallasii in Port Angeles Harbor, WA, USA. Infestation prevalence on newly metamorphosed age 0 Pacific herring reached 100% prevalence by mid-August. At this time, the mean louse intensity was 4.6 lice/fish, and a positive correlation occurred between louse intensity and herrin
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David James Páez, Jacob L. Gregg, Ashley MacKenzie, Sophie Amanda Hall, Paul Hershberger
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Ecosystems Mission Area, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)

A phylogeny based on cytochrome-c oxidase gene sequences identifies sympatric Ichthyophonus genotypes in the NE Pacific Ocean

ABSTRACT: In recent decades, evidence has accumulated to suggest that the widespread and highly variable parasite Ichthyophonus hoferi is actually a species complex. Highly plastic morphology and a general lack of defining structures has contributed to the likely underestimate of biodiversity within this group. Molecular methods are a logical next step in the description of these parasites, but ma
Authors
Jacob L. Gregg, Paul Hershberger, Abigail S. Neat, Hiruni T. Jayasekera, Jayde A. Ferguson, Rachel L. Powers, Maureen K. Purcell
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Ecosystems Mission Area, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Annual recurrences of viral hemorrhagic septicemia epizootics in age 0 Pacific herring Clupea pallasii Valenciennes, 1847

Throughout a 20 year biosurveillance period, viral hemorrhagic septicemia virus was isolated in low titers from only 6/7355 opportunistically sampled adult Pacific herring, reflecting the typical endemic phase of the disease when the virus persists covertly. However, more focused surveillance efforts identified the presence of disease hot spots occurring among juvenile life history stages from cer
Authors
Paul Hershberger, Theodore R. Meyers, Jacob L. Gregg, Maya Groner, Sophie Amanda Hall, Hiruni T. Jayasekera, Ashley MacKenzie, Abigail S. Neat, Ella N. Piatt, Kyle A. Garver
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Long-term shedding from fully convalesced individuals indicates that Pacific herring are a reservoir for viral hemorrhagic septicemia virus

Processes that allow viral hemorrhagic septicemia (VHS) virus to persist in the marine environment remain enigmatic, owing largely to the presence of covert and cryptic infections in marine fishes during typical sub-epizootic periods. As such, marine host reservoirs for VHS virus have not been fully demonstrated, nor have the mechanism(s) by which infected hosts contribute to virus perpetuation an
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Paul Hershberger, Ashley MacKenzie, Jacob L. Gregg, M. D. Wilmot, Rachel L. Powers, Maureen K. Purcell
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Differential susceptibility of Yukon River and Salish Sea stocks of Chinook salmon Oncorhynchus tshawytscha to ichthyophoniasis

Preliminary evidence suggests that Chinook salmon Oncorhynchus tshawytscha from the Yukon River may be more susceptible to Ichthyophonus sp. infections than Chinook from stocks further south. To investigate this hypothesis in a controlled environment, we experimentally challenged juvenile Chinook from the Yukon River and from the Salish Sea with Ichthyophonus sp. and evaluated mortality, infection
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Diane G. Elliott, Carla M. Conway, Constance L. McKibben, Ashley MacKenzie, Lucas M. Hart, Maya Groner, Maureen K. Purcell, Jacob L. Gregg, Paul Hershberger
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Pacific herring Clupea pallasii are not susceptible to vibriosis from Vibrio anguillarum or V. ordalii under laboratory conditions

The ubiquity of Vibrio spp. throughout the coastal marine waters of the Pacific Northwest of North America raises questions about the susceptibility of native marine fishes, including Pacific herring (Clupea pallasii). Early reports of Vibriolike disease (Rucker et al., 1954; Walford, 1958) and Vibrio sp. isolations (Pacha & Kiehn, 1969) in Pacific herring remain questionable because both occurred
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Paul Hershberger, M.E.T Stinson, Brenda L Hall, Ashley MacKenzie, Jacob L. Gregg, William August Richards, James Winton
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Ichthyophonus in sport-caught groundfishes from southcentral Alaska

This report of Ichthyophonus in common sport-caught fishes throughout the marine waters of southcentral Alaska represents the first documentation of natural Ichthyophonus infections in lingcod Ophiodon elongates and yelloweye rockfish Sebastes ruberrimus. In addition, the known geographic range of Ichthyophonus in black rockfish S. melanops has been expanded northward to include southcentral Alask
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Bradley P. Harris, Sarah R. Webster, Nathan Wolf, Jacob L. Gregg, Paul Hershberger
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Ecosystems Mission Area, Species Management Research Program, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)

High‐prevalence and low‐intensity Ichthyophonus infections in Pacific Halibut

Ichthyophonus occurred at high prevalence but low intensity in Pacific Halibut Hippoglossus stenolepis throughout the West Coast of North America, ranging from coastal Oregon to the Bering Sea. Infection prevalence in adults was variable on spatial and temporal scales, with the lowest prevalence typically occurring on the edges of the geographic range and highest prevalence consistently occurring
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Paul Hershberger, Jacob L. Gregg, Claude L. Dykstra
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Fisheries Research Center, Marrowstone Marine Field Station (MMFS)

Identification of the major capsid protein of erythrocytic necrosis virus (ENV) and development of quantitative real-time PCR assays for quantification of ENV DNA

Viral erythrocytic necrosis (VEN) is a disease of marine and anadromous fish that is caused by the erythrocytic necrosis virus (ENV), which was recently identified as a novel member of family Iridoviridae by next-generation sequencing. Phylogenetic analysis of the ENV DNA polymerase grouped ENV with other erythrocytic iridoviruses from snakes and lizards. In the present study, we identified the ge
Authors
Maureen K. Purcell, Schuyler Pearman-Gillman, Rachel L. Thompson, Jacob L. Gregg, Lucas M. Hart, James R. Winton, Eveline J. Emmenegger, Paul K. Hershberger
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Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Ichthyophonus parasite phylogeny based on ITS rDNA structure prediction and alignment identifies six clades, with a single dominant marine type

Despite their widespread, global impact in both wild and cultured fishes, little is known of the diversity, transmission patterns, and phylogeography of parasites generally identified as Ichthyophonus. This study constructed a phylogeny based on the structural alignment of internal transcribed spacer (ITS) rDNA sequences to compare Ichthyophonus isolates from fish hosts in the Atlantic and Pacific
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Jacob Gregg, Rachel L. Thompson, Maureen K. Purcell, Carolyn S. Friedman, Paul Hershberger
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Ecosystems Mission Area, Species Management Research Program, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

The parasite Ichthyophonus sp. in Pacific herring from the coastal NE Pacific

The protistan parasite Ichthyophonus occurred in populations of Pacific herring Clupea pallasii Valenciennes throughout coastal areas of the NE Pacific, ranging from Puget Sound, WA north to the Gulf of Alaska, AK. Infection prevalence in local Pacific herring stocks varied seasonally and annually, and a general pattern of increasing prevalence with host size and/or age persisted throughout the NE
Authors
Paul K. Hershberger, Jacob L. Gregg, Lucas M. Hart, Steve Moffitt, Richard L. Brenner, K. Stick, Eric Coonradt, E. O. Otis, Johanna J. Vollenweider, Kyle A. Garver, Jan Lovy, T.R. Meyers
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Ecosystems Mission Area, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

Molecular identification of erythrocytic necrosis virus (ENV) from the blood of Pacific herring (Clupea pallasii)

Viral erythrocytic necrosis (VEN) is a condition affecting the red blood cells of more than 20 species of marine and anadromous fishes in the North Atlantic and North Pacific Oceans. Among populations of Pacific herring (Clupea pallasii) on the west coast of North America the disease causes anemia and elevated mortality in periodic epizootics. Presently, VEN is diagnosed by observation of typical
Authors
Eveline J. Emmenegger, Jolene A. Glenn, James R. Winton, William N. Batts, Jacob L. Gregg, Paul K. Hershberger
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Ecosystems Mission Area, Western Fisheries Research Center, Fish Health Program (FHP), Marrowstone Marine Field Station (MMFS)

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