6 research outputs found
Recommended from our members
Survey of Pathogens in Hatchery Chinook Salmon with Different Out-Migration Histories through the Snake and Columbia Rivers
The operation of the Federal Columbia River Power System (FCRPS) has negatively affected threatened and endangered salmonid populations in the Pacific Northwest. Barging Snake River spring Chinook salmon Oncorhynchus tshawytscha through the FCRPS is one effort to mitigate the effect of the hydrosystem on juvenile salmon out-migration. However, little is known about the occurrence and transmission of infectious agents in barged juvenile salmon relative to juvenile salmon that remain in-river to navigate to the ocean. We conducted a survey of hatchery-reared spring Chinook salmon at various points along their out-migration path as they left their natal hatcheries and either migrated in-river or were barged through the FCRPS. Salmon kidneys were screened by polymerase chain reaction for nine pathogens and one family of water molds. Eight pathogens were detected; the most prevalent were Renibacterium salmoninarum and infectious hematopoietic necrosis virus. Species in the family Saprolegniaceae were also commonly detected. Pathogen prevalence was significantly greater in fish that were barged through the FCRPS than in fish left to out-migrate in-river. These results suggest that the transmission of infectious agents to susceptible juvenile salmon occurs during the barging process. Therefore, management activities that reduce pathogen exposure during barging may increase the survival of juvenile Chinook salmon after they are released.Keywords: Oncorhynchus tshawytscha, Pacific Northwest, hatchery, pathogens, juvenile
Assimilation Efficiency of PBDE Congeners in Chinook Salmon
Polybrominated
diphenyl ether (PBDE) flame retardants are environmental
contaminants that can accumulate in biota. PBDE accumulation in an
organism depends on exposure, assimilation efficiency, and elimination/metabolism.
Net assimilation efficiency represents the fraction of the contaminant
that is retained in the organism after exposure. In the present study,
congener-specific estimates of net PBDE assimilation efficiencies
were calculated from dietary exposures of juvenile Chinook salmon.
The fish were exposed to one to eight PBDE congeners up to 1500 ng
total PBDEs/g food. Mean assimilation efficiencies varied from 0.32
to 0.50 for BDE congeners 28, 47, 99, 100, 153, and 154. The assimilation
efficiency of BDE49 was significantly greater than 100%, suggesting
biotransformation from higher brominated congeners. Whole body concentrations
of BDE49 significantly increased with both exposure to increasing
concentrations of BDE99 and decreasing fish lipid levels, implying
lipid-influenced debromination of BDE99 to BDE49. Excluding BDE49,
PBDE assimilation efficiency was not significantly related to the
numbers of congeners in the diets, or congener hydrophobicity, but
was greater in foods with higher lipid levels. Estimates of PBDE assimilation
efficiency can be used in bioaccumulation models to assess threats
from PBDE exposure to Chinook salmon health and recovery efforts,
as well as to their predators