Skip to main content
Advanced Search

Filters: Tags: {"type":"Harvest Set"} (X) > partyWithName: Paul K Hershberger (X)

5 results (9ms)   

View Results as: JSON ATOM CSV
thumbnail
Throughout a 20-year biosurveillance period, viral hemorrhagic septicemia virus was isolated in low titers from only 6 / 7,355 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 certain nearshore habitats. These outbreaks sometimes recurred annually in the same temporal and spatial patterns and were characterized by infection prevalence as high as 96%. Longitudinal sampling indicated that some epizootics were relatively transient, represented by positive samples on a single sampling date, and others...
thumbnail
Controlled waterborne exposures of Pacific herring (Clupea pallasii) to Vibrio anguillarum and V. ordalii failed to result in overt signs of disease or mortality from vibriosis. Cumulative mortalities among Vibrio - exposed Pacific herring (3.3 - 5.0%) were similar to those of saline-exposed negative controls (10%) and significantly less (P < 0.001) than those of Vibrio - exposed Chinook salmon (60 - 97%), a known susceptible species. Gross signs of disease did not occur on any dead or surviving Pacific herring; however, exposed Chinook salmon demonstrated classic gross signs of vibriosis. The results indicate that early reports of presumed vibriosis in Pacific herring during the 1950’s were likely misdiagnosed...
Nuclear inclusion X (NIX), the etiological agent of bacterial gill disease in Pacific razor clams (Siliqua patula) was associated with host mortality events in coastal Washington, USA during the mid-1980s. Ongoing observations of truncated razor clam size distributions in Kalaloch Beach, Washington raised concerns that NIX continues to impact populations. We conducted a series of spatial and longitudinal NIX surveillances, examined archived razor clam gill tissue, and used population estimates from stock assessments to test whether: a) the prevalence and intensity of NIX infections is higher at Kalaloch Beach relative to nearby beaches b) infected gill tissue has features consistent with historical descriptions...
thumbnail
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 herring body length. The epizootic then waned, with infestation prevalence decreasing to less than 25% and the mean parasite intensity falling below 1 louse by October. In controlled experiments, louse-induced mortality was negligible in controlled experiments. While skin injuries were not detected, motile lice preferentially...
The ability of formalin, PEROX-AID® (hydrogen peroxide), and seawater to kill waterborne Nanophyetus salmincola cercariae was evaluated in vitro. Newly emerged waterborne cercariae survived for extended periods in freshwater, with 50-74% survival occurring in negative control groups after 24 hr. Exposure to dilutions of formalin reduced this survival time, with 0% of cercariae surviving after 30 min. in 167 ppm, 40 min. in 83 ppm, and 180 min. in 42ppm. Exposure to PEROX-AID® (hydrogen peroxide) for one hour resulted in reduced cercariae survival (16.4%) only at the highest concentration (100 ppm), compared to 100% survival in the untreated controls and all lesser concentrations. Dilutions of seawater resulted in...
    map background search result map search result map Laboratory challenge of Pacific herring Clupea pallasii to Vibrio anguillarum and V. ordallii Survey of viral hemorrhagic septicemia virus in Pacific herring throughout the North Pacific Ocean Histological and molecular testing of nuclear inclusion X in Pacific Razor clams from select locations in Washington, USA 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 Laboratory challenge of Pacific herring Clupea pallasii to Vibrio anguillarum and V. ordallii Histological and molecular testing of nuclear inclusion X in Pacific Razor clams from select locations in Washington, USA 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 Survey of viral hemorrhagic septicemia virus in Pacific herring throughout the North Pacific Ocean