Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 1132
Title: Survey of Pathogens in Hatchery Chinook Salmon with Different Outmigration Histories through the Snake and Columbia Rivers
Author: A. L. Van Gaest, J. P. Dietrich, D. E. Thompson, D. Boylen, S. A. Strickland, T. K. Collier, F. J. Loge, M. R. Arkoosh
Publication Year: 2011
Journal: Journal of Aquatic Animal Health
Volume: 23
Issue: 2
Pages: 62-77
DOI: 10.1080/00028487.2011.572023
Keywords: Columbia River, Snake River, Chinook Salmon, salmon, disease, Renibacterium salmoninarum, Saprolegniasis, IHNV, FCRPS, barge transport, delayed mortality, hydropower system, hatchery
Abstract: 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.