Overwinter shifts in the feeding ecology of juvenile Chinook salmon

Last modified: 
August 29, 2016 - 6:24pm
Type: Journal Article
Year of publication: 2016
Date published: 08/2016
Authors: Eric Hertz, Marc Trudel, Strahan Tucker, Terry Beacham, Asit Mazumder
Journal title: ICES Journal of Marine Science
Pages: fsw140
ISSN: 1054-3139

Winter is thought to be a critical period for many fish in the ocean, but their ecology during this time tends to be poorly understood. We quantified the feeding ecology of juvenile Chinook salmon (Oncorhynchus tshawytscha) off the west coast of Vancouver Island in British Columbia, Canada, in autumn and winter to determine how seasonality could affect diet. Using stomach contents and stable isotopes, we tested the hypothesis that the winter diet of juvenile Chinook salmon differs from that of the autumn diet. Stomach-content data showed a shift from a primary reliance on amphipods in autumn to euphausiids in winter. This finding was generally corroborated by the stable isotope analysis, although mixing models suggested a greater contribution of fish prey to the diet in both autumn and winter. Understanding the diet of fish during winter may provide useful information for management as a first step in understanding the factors influencing mortality across life stages.

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