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Trophic interactions and consumption rates of subyearling Chinook Salmon and nonnative juvenile American Shad in Columbia River reservoirs

Transactions of the American Fisheries Society

By:
ORCID iD , ORCID iD , and
https://doi.org/10.1080/00028487.2016.1264997

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Abstract

We used a large lampara seine coupled with nonlethal gastric lavage to examine the diets and estimate consumption rates of subyearling Chinook Salmon Oncorhynchus tshawytscha during July and August 2013. During August we also examined the diet and consumption rates of juvenile American Shad Alosa sapidissima, a potential competitor of subyearling Chinook Salmon. Subyearling Chinook Salmon consumed Daphnia in July but switched to feeding on smaller juvenile American Shad in August. We captured no juvenile American Shad in July, but in August juvenile American Shad consumed cyclopoid and calanoid copepods. Stomach evacuation rates for subyearling Chinook Salmon were high during both sample periods (0.58 h−1 in July, 0.51 h−1 in August), and daily ration estimates were slightly higher than values reported in the literature for other subyearlings. By switching from planktivory to piscivory, subyearling Chinook Salmon gained greater growth opportunity. While past studies have shown that juvenile American Shad reduce zooplankton availability for Chinook Salmon subyearlings, our work indicates that they also become important prey after Daphnia abundance declines. The diet and consumption data here can be used in future bioenergetics modeling to estimate the growth of subyearling Chinook Salmon in lower Columbia River reservoirs.

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Trophic interactions and consumption rates of subyearling Chinook Salmon and nonnative juvenile American Shad in Columbia River reservoirs
Series title:
Transactions of the American Fisheries Society
DOI:
10.1080/00028487.2016.1264997
Volume:
146
Issue:
2
Year Published:
2017
Language:
English
Publisher:
Taylor & Francis
Contributing office(s):
Western Fisheries Research Center
Description:
Report: 7 p.
First page:
291
Last page:
298
Country:
United States
State:
Washington