Authors
Jeffrey Fryer
Report Reference
#04-01
Publication Date
18 March
2004
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Identification
of Columbia Basin Sockeye Salmon Stocks in 2003
Abstract |
| In 2003,
samples of adult Columbia Basin sockeye salmon, Oncorhynchus nerka,
were collected at Bonneville Dam as well as at Tumwater Dam on the
Wenatchee River and Wells Dam in the mid-Columbia River downstream
of the Okanogan River. Tumwater and Wells dams were chosen to provide
samples of sockeye salmon from the two principle stocks of Columbia
Basin sockeye salmon, which originate from the Wenatchee and Okanogan
basins. Age composition was estimated from the sampled sockeye salmon
passing the three dams. Five-year-old fish were estimated to comprise
28% of the Bonneville Dam mixed-stock, 16% of the Okanogan stock,
and 92% of the Wenatchee stock. Four-year-old fish were estimated
to comprise 38% of the mixed-stock sockeye salmon migrating past Bonneville
Dam, 57% of the Okanogan stock migrating past Wells Dam, and 1% of
the Wenatchee stock migrating past Tumwater Dam. Three-year-old fish
were estimated to comprise 25% of the Bonneville Dam mixed-stock,
27% of the Okanogan stock and none of the Wenatchee stock. Six-year-
old fish were estimated to comprise 8% of the Bonneville Dam mixed-stock,
3% of the Okanogan stock and 7% of the Wenatchee stock. For the first
time in 18 years of CRITFC Columbia River sockeye salmon studies,
the age composition of the Okanogan stock and Wenatchee stock differed
sufficiently to differentiate stocks at Bonneville Dam by age alone
rather than using scale pattern analysis techniques on common age
classes. We estimated that 84% of the sockeye salmon passing Bonneville
Dam were of Okanogan origin while 16% were of Wenatchee stock. |
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