Previous studies have shown that juvenile chinook salmon Oncorhynchus tshawytscha exposed in the field or the laboratory to polychlorinated biphenyls (PCBs), an anthropogenic stressor, are immunosuppressed. It is not known whether simultaneous exposure to natural stressors can increase this immunosuppression. To examine the effects of natural and anthropogenic stressors on...
During the summer of 1994, 1996, and 1997, we conducted hydrographic and plankton surveys of the upper 70 m in the nearshore, the continental shelf, and off shelf oceanic waters off Oregon, USA. Copepod densities and biomass were estimated along 4 transects from each cruise. The on shelf copepod biomass...
The lingcod Ophiodon elongatus is a benthic marine fish commonly caught by groundfish trawlers and discarded due to low catch limits. Managers must account for the mortality of bycatch to assess population status accurately. Our objectives were to estimate the actual mortality of trawl-discarded lingcod (50- 84 cm) and describe...
Tag and recovery programs can provide valuable information on population size and exploitation rates in fishes. Passive integrated transponder (PIT) tags are ideal for use in such programs because they provide identification of individual fish and are invisible to anglers, circumventing problems with nonreporting of tags. Our objective was to...
Changes in the spatial distribution of U.S. west coast bottom-trawl effort in relation
to areas of prime habitat for rockfish Sebastes spp. were evaluated between 1992 and 2001. Prime trawlable rockfish habitat (PTRH) was defined based on the spatial distribution of high rockfish catches from logbook data for 1992–1995. Bottom-trawl...
Simultaneous visual and oceanographic surveys were conducted in the lower Bay of Fundy and in Roseway Basin of the SW Scotian Shelf during the summers of 1999 to 2001 to investigate the physical and biological oceanographic factors associated with North Atlantic right whale occurrence. Sightings of right whales were recorded...
North Atlantic right whales were instrumented with suction-cup mounted, time-depth recorders (TDR) during the summers of 2000 and 2001 to examine their diving and foraging behavior. Simultaneous observations of temperature, salinity and the vertical distribution of their principal prey, Calanus finmarchicus stage 5 copepodites (C5), were obtained alon
g each...
Fisheries models often assume that discarded undersized fish and target species will survive and contribute to future recruitment and yield. If smaller fish are more susceptible to capture stressors than larger fish, then the assumption that smaller discards would contribute to recruitment may not be true. We tested the hypothesis...
Assessments for many U.S. Pacific coast groundfish stocks have been developed using the statistical catch-at-age method known as Stock Synthesis. This study used Monte Carlo simulation and a fractional factorial experiment to evaluate the effects of input data errors and stock characteristics on bias and precision in estimates of ending...
Although the adverse impact of pathogens on salmon populations in the Pacific Northwest is often discussed and recognized, little is currently known regarding the incidence and corresponding significance of delayed disease-induced mortalities. In the study reported herein, we surveyed the presence and prevalence of selected micro- and macroparasites in out-migrant...
"Erosion is impacting a portion of the Estuary Nature Trail located adjacent to Oregon State University's Hatfield Marine Science Center (HMSC) facility, located on the south side of the Yaquina Bay estuary approximately one mile from the open waters of the Pacific Ocean. The HMSC Estuary Nature Trail is important...
Describing the ocean habitats used by Chinook salmon Oncorhynchus tshawytscha is an important step towards understanding how environmental conditions influence their population dynamics. We used data from archival tags that recorded time, temperature and pressure (depth) to define the coastal habitats used by Chinook near Oregon and California during the...
This is a summary report of preliminary recommendations for the Oregon State
University: Hatfield Marine Science Center, located in Newport, Lincoln County, Oregon
as this institution prepares to embark on the development of an earthquake and tsunami
pre-disaster mitigation plan. This report describes our preliminary recommendations,
lessons from the past,...
This is a summary report of preliminary recommendations for the Oregon State
University: Hatfield Marine Science Center, located in Newport, Lincoln County, Oregon
as this institution prepares to embark on the development of an earthquake and tsunami pre-disaster mitigation plan. This report describes our preliminary recommendations, lessons from the past,...
We tested the potential of a selective flatfish trawl to reduce bycatch of slope rockfish in the upper continental slope bottom-trawl fishery (250–500 m) on the U.S. West Coast. The trawl we tested differed from typical slope trawls in that it was a low-rise, two-seam trawl with a severely cut...
If the success of the Endangered Species Act (ESA) is measured by the number of endangered species that have been recovered and delisted, then the act is not very successful. Only 15 species have been delisted because of recovery in the history of the ESA. The Borax Lake chub (Gila...