Jacob Gregg
Science and Products
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...
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. Survival and growth of juvenile Pacific lampreys tagged with passive integrated transponders (PIT) in freshwater and seawater
Tagging methods are needed for both adult and juvenile life stages of Pacific lampreys Lampetra tridentata to better understand their biology and factors contributing to their decline. We developed a safe and efficient technique for tagging juvenile Pacific lampreys with passive integrated transponder (PIT) tags. We tested the short-term survival...
Mesa, Matthew G.; Copeland, Elizabeth S.; Christiansen, Helena E.; Gregg, Jacob L.; Roon, Sean R.; Hershberger, Paul K. Susceptibility of Pacific herring to viral hemorrhagic septicemia is influenced by diet
Groups of specific-pathogen-free Pacific herring Clupea pallasii were highly susceptible to infection by viral hemorrhagic septicemia virus (VHSV); however, the level of mortality was influenced by diet during the 40–71 d before, during, and after the first exposure to the virus. Cumulative mortality was highest among the herring maintained on an...
Beaulaurier, Joshua; Bickford, N.; Gregg, J.L.; Grady, C.A.; Gannam, A.L.; Winton, J.R.; Hershberger, P.K. Efficacy of a glycoprotein DNA vaccine against viral haemorrhagic septicaemia (VHS) in Pacific herring, Clupea pallasii Valenciennes
Viral haemorrhagic septicaemia virus (VHSV) and its associated disease state, viral haemorrhagic septicaemia (VHS), is hypothesized to be a proximate factor accounting for the decline and failed recovery of Pacific herring populations in Prince William Sound, AK (Marty et al. 1998, 2003, 2010). Survivors of laboratory-induced VHSV epizootics...
Hart, L.M.; Lorenzen, Niels; LaPatra, S.E.; Grady, C.A.; Roon, S.E.; O’Reilly, J.; Gregg, J.L.; Hershberger, P.K. Inability to demonstrate fish-to-fish transmission of Ichthyophonus from laboratory infected Pacific herring Clupea pallasii to naïve conspecifics
The parasite Ichthyophonus is enzootic in many marine fish populations of the northern Atlantic and Pacific Oceans. Forage fishes are a likely source of infection for higher trophic level predators; however, the processes that maintain Ichthyophonus in forage fish populations (primarily clupeids) are not well understood. Lack...
Gregg, J.L.; Grady, C.A.; Friedman, C.S.; Hershberger, P.K.