Jacob Gregg
Science and Products
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.
PAH Exposure and Disease Susceptibility
Researchers at the MMFS are studying the immediate and delayed effects of petroleum hydrocarbon exposures to Pacific herring.
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...
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...
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...
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...
Hershberger, Paul; Meyers, Theodore R.; Gregg, Jacob L.; Groner, Maya; Hall, Sophie Amanda; Jayasekera, Hiruni T.; Mackenzie, Ashley; Neat, Abigail S.; Piatt, Ella N.; Garver, Kyle A. 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...
Hershberger, Paul; Mackenzie, Ashley; Gregg, Jacob L.; Wilmot, M. D.; Powers, Rachel L.; Purcell, Maureen K. 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...
Elliott, Diane G.; Conway, Carla M.; McKibben, Constance L.; Mackenzie, Ashley; Hart, Lucas M.; Groner, Maya; Purcell, Maureen K.; Gregg, Jacob L.; Hershberger, Paul 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...
Hershberger, Paul; Stinson, M.E.T; Hall, Brenda L; Mackenzie, Ashley; Gregg, Jacob L.; Richards, William August; Winton, James 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 ...
Harris, Bradley P.; Webster, Sarah R.; Wolf, Nathan; Gregg, Jacob L.; Hershberger, Paul 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...
Hershberger, Paul; Gregg, Jacob L.; Dykstra, Claude L. 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...
Purcell, Maureen K.; Pearman-Gillman, Schuyler; Thompson, Rachel L.; Gregg, Jacob L.; Hart, Lucas M.; Winton, James R.; Emmenegger, Eveline J.; Hershberger, Paul K. 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...
Gregg, Jacob; Thompson, Rachel L.; Purcell, Maureen K.; Friedman, Carolyn S.; Hershberger, Paul 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...
Hershberger, Paul K.; Gregg, Jacob L.; Hart, Lucas M.; Moffitt, Steve; Brenner, Richard L.; Stick, K.; Coonradt, Eric; Otis, E. O.; Vollenweider, Johanna J.; Garver, Kyle A.; Lovy, Jan; Meyers, T.R. 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....
Emmenegger, Eveline J.; Glenn, Jolene A.; Winton, James R.; Batts, William N.; Gregg, Jacob L.; Hershberger, Paul K. Distribution and transmission of the highly pathogenic parasite Ichthyophonus in marine fishes of Alaska
A combination of field surveys, molecular typing, and laboratory experiments were used to improve our understanding of the distribution and transmission mechanisms of fish parasites in the genus Ichthyophonus. Ichthyophonus spp. infections were detected from the Bering Sea to the coast of Oregon in 10 of 13 host species surveyed. Sequences of rDNA...
Gregg, Jacob L.; Grady, Courtney A.; Thompson, Rachel L.; Purcell, Maureen K.; Friedman, Carolyn S.; Hershberger, Paul K. Influence of temperature on viral hemorrhagic septicemia (Genogroup IVa) in Pacific herring, Clupea pallasii Valenciennes
An inverse relationship between water temperature and susceptibility of Pacific herring (Clupea pallasii) to viral hemorrhagic septicemia, genogroup IVa (VHS) was indicated by controlled exposure studies where cumulative mortalities, viral shedding rates, and viral persistence in survivors were greatest at the coolest exposure temperatures. Among...
Hershberger, P.K.; Purcell, M. K.; Hart, L.M.; Gregg, J.L.; Thompson, R.L.; Garver, K.A.; Winton, J.R.