Jacob Gregg
Jacob is a Fish Biologist at the Marrowstone Marine Field Station, Nordland, WA.
Science and Products
Filter Total Items: 44
Feasibility 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 a
Authors
Paul K. Hershberger, Jacob L. Gregg, A.C. Seitz, Brenda L. Norcross, J.C. Payne, A.N. Kagley, B Meloy
Prevalence 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 se
Authors
P.K. Hershberger, N.E. Elder, C.A. Grady, J.L. Gregg, C.A. Pacheco, C. Greene, C. Rice, T.R. Meyers
Differential 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 th
Authors
P.K. Hershberger, C.A. Pacheco, J.L. Gregg, M. K. Purcell, S. E. LaPatra
Inactivation 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 tes
Authors
P.K. Hershberger, C.A. Pacheco, J.L. Gregg
Larval 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, cumulati
Authors
P.K. Hershberger, J. Gregg, C. Pacheco, J. Winton, J. Richard, G. Traxler
Dynamics of viral hemorrhagic septicemia, viral erythrocytic necrosis and ichthyophoniasis in confined juvenile Pacific herring Clupea pallasii
Capture of wild, juvenile herring Clupea pallasii from Puget Sound (Washington, USA) and confinement in laboratory tanks resulted in outbreaks of viral hemorrhagic septicemia (VHS), viral erythrocytic necrosis (VEN) and ichthyophoniasis; however, the timing and progression of the 3 diseases differed. The VHS epidemic occurred first, characterized by an initially low infection prevalence that incre
Authors
P. Hershberger, A. Hart, J. Gregg, N. Elder, J. Winton
Ichthyophonus-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, infiltrati
Authors
R. Kocan, S. LaPatra, J. Gregg, J. Winton, P. Hershberger
Improving the precision of otolith-based age estimates for Greenland halibut (Reinhardtius hippoglossoides) with preparation methods adapted for fragile sagittae
[No abstract available]
Authors
J.L. Gregg, D.M. Anderl, D.K. Kimura
Science and Products
Filter Total Items: 44
Feasibility 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 a
Authors
Paul K. Hershberger, Jacob L. Gregg, A.C. Seitz, Brenda L. Norcross, J.C. Payne, A.N. Kagley, B Meloy
Prevalence 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 se
Authors
P.K. Hershberger, N.E. Elder, C.A. Grady, J.L. Gregg, C.A. Pacheco, C. Greene, C. Rice, T.R. Meyers
Differential 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 th
Authors
P.K. Hershberger, C.A. Pacheco, J.L. Gregg, M. K. Purcell, S. E. LaPatra
Inactivation 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 tes
Authors
P.K. Hershberger, C.A. Pacheco, J.L. Gregg
Larval 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, cumulati
Authors
P.K. Hershberger, J. Gregg, C. Pacheco, J. Winton, J. Richard, G. Traxler
Dynamics of viral hemorrhagic septicemia, viral erythrocytic necrosis and ichthyophoniasis in confined juvenile Pacific herring Clupea pallasii
Capture of wild, juvenile herring Clupea pallasii from Puget Sound (Washington, USA) and confinement in laboratory tanks resulted in outbreaks of viral hemorrhagic septicemia (VHS), viral erythrocytic necrosis (VEN) and ichthyophoniasis; however, the timing and progression of the 3 diseases differed. The VHS epidemic occurred first, characterized by an initially low infection prevalence that incre
Authors
P. Hershberger, A. Hart, J. Gregg, N. Elder, J. Winton
Ichthyophonus-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, infiltrati
Authors
R. Kocan, S. LaPatra, J. Gregg, J. Winton, P. Hershberger
Improving the precision of otolith-based age estimates for Greenland halibut (Reinhardtius hippoglossoides) with preparation methods adapted for fragile sagittae
[No abstract available]
Authors
J.L. Gregg, D.M. Anderl, D.K. Kimura