Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8600
Title: Ontogenetic shifts in diets of juvenile Chinook salmon: new insight from stable isotopes and fatty acids
Author: Marisa N.C. Litz, Jessica A. Miller, Louise A. Copeman, David J. Teel, Laurie A. Weitkamp, Elizabeth A. Daly, Andrew M. Claiborne
Publication Year: 2016
Journal: Environmental Biology of Fishes
DOI: 10.1007/s10641-016-0542-5.
Keywords: Chinook salmon,stable isotopes,fatty acid,diets

Variations in marine prey availability and nutritional quality can affect juvenile salmon growth and survival during early ocean residence. Salmon growth, and hence survival, may be related to the onset of piscivory, but there is limited knowledge on the interplay between the prey field, environment, and salmon ontogeny. Subyearling Chinook Salmon (Oncorhynchus tshawytscha) and their potential prey were sampled in coastal waters off Willapa Bay, USA. Three seasonal prey assemblages were identified, occurring in spring (May), early summer (June – July), and late summer (August – September). The onset of piscivory, based on salmon stomach contents, fatty acids, and stable isotopes occurred later in 2011 compared to 2012, and coincided with the appearance of Northern Anchovy (Engraulis mordax). Salmon fork length (FL) and carbon isotope values increased significantly with a fatty acid biomarker for marine phytoplankton and significantly decreased with a freshwater marker, indicating dietary carbon sources transitioned as salmon emigrated from the Columbia River. Salmon FL also increased significantly with nitrogen isotope ratios (δ15N), trophic position, and a fatty acid marker for carnivory – a consequence of the ontogenetic shift in diet to piscivory. Salmon grew faster and obtained larger size and condition by September 2011 compared to 2012, which may be related to inter-annual differences in ocean conditions and the duration over which Northern Anchovy were available. Our results lend support to the idea that juvenile salmon growth is related to the onset and duration of piscivory, suggesting both of these factors may be important components of lifetime growth and fitness.


Used stable isotopes and fatty acids to document the response of juvenile salmon to changes in available prey in marine waters off the mouth of the Columbia River.

Theme: Ecosystem approach to improve management of marine resources
Foci: Understand how climate influences ecosystem variability.
Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species.
Official Citation:

Litz, M. N., J. A. Miller, L. A. Copeman, D. J. Teel, L. A. Weitkamp, E. A. Daly, and A. M. Claiborne.  2016 Ontogenetic shifts in the diets of juvenile Chinook salmon: new insight from stable isotopes and fatty acids.  Environmental Biology of Fishes. DOI 10.1007/s10641-016-0542-5.