Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7435
Title: Infections by Renibacterium salmoninarum and Nanophyetus salmincola Chapin are associated with reduced growth of juvenile Chinook salmon, Oncorhynchus tshawytscha (Walbaum), in the Northeast Pacific Ocean
Author: T. A. Sandell, David J. Teel, J. Fisher, Brian R. Beckman, K. C. Jacobson
Publication Year: 2015
Journal: Journal of Fish Diseases
Volume: 38
Issue: 4
Pages: 365-378
Keywords: pathogens,parasites,Chinook salmon,ocean

We examined 1,454 juvenile Chinook salmon, Oncorhynchus tshawytscha (Walbaum), captured in nearshore waters off the coasts of Washington and Oregon (U.S.A.) from 1999-2004 for infection by Renibacterium salmoninarum, Nanophyetus salmincola, and skin metacercariae.  The prevalences and intensities for each of these infections were established for both yearling and subyearling Chinook salmon.  Two metrics of salmon growth, weight residuals and plasma levels of insulin–like growth factor–1, were determined for salmon infected with these pathogens/parasites, both individually and in combination.  One stock of subyearlings infected by N. salmincola had significantly reduced weight residuals compared to uninfected fish; yearling stocks showed no effect.  Yearling Chinook salmon infected with R. salmoninarum had significantly reduced weight residuals.  Chinook salmon infected with skin metacercariae alone did not have significantly reduced growth metrics.  Dual infections were not associated with significantly more severe effects on the growth metrics than single infections; the number of triple infections was very low and precluded statistical comparison.  Overall, these data suggest that infection by these organisms is associated with reduced juvenile Chinook salmon growth.  Because growth in the first year at sea has been linked to survival, the infections may therefore play a role in regulating Chinook salmon populations in the northeast Pacific Ocean.

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Theme: Ecosystem approach to improve management of marine resources
Foci: Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species.
Characterize the interaction between marine, freshwater and terrestrial ecosystem components.