Authors
Saang-Yoon
Hyun
Katherine W. Myers
André Talbot
Report Reference
#Fisheries
Oceanography
16:4, 350-362, 2007
Publication Date
2007
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Year-to-year
variability in ocean recovery rate of Columbia River Upriver Bright fall
Chinook salmon (Oncorhynchus tshawytscha)
Abstract |
Unusually
large returns of several stocks of fall Chinook salmon (Oncorhynchus
tshawytscha) from the U.S. Northwest commonly occurred during
the late 1980s. These synchronous events seem to have been due to
ocean rather than freshwater conditions because natal rivers of these
stocks were geographically disconnected. We examined year-to-year
variability in cohort strength of one of these stocks, Upriver Bright
(URB) fall Chinook salmon from the Columbia River Hanford Reach for
brood years 1976–99 (recovery years 1979–2002). We used
the ocean recovery rate of coded-wire-tag (CWT) fish as an index of
cohort strength. To analyse year-to-year variability in the ocean
recovery rate, we applied a log-linear model whose candidate explanatory
variables were ocean condition variables, fishing effort, age of recovered
fish, and fish rearing type (hatchery versus wild). Explanatory variables
in the best model included fishing effort, and the quadratic term
of winter sea surface temperature (SST) measured from coastal waters
of British Columbia, Canada during the fish’s first ocean year.
The coefficient of the quadratic term of SST was significantly negative,
so the model shape was convex. Our findings can be used to infer year-to-year
variability in cohort strength of other fallChinook salmon whose life
history and ocean
distributions are similar to the URB fish. |
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