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Identification of Columbia Basin Sockeye Salmon Stocks Using Scale Pattern Analyses in 2002

Apr 20, 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 55% of the Bonneville Dam mixed-stock, 40% of the Okanogan stock, and 58% of the Wenatchee stock. Four-year-old fish were estimated to comprise 40% of the mixed-stock sockeye salmon migrating past Bonneville Dam, 44% of the Okanogan stock migrating past Wells Dam, and 42% of the Wenatchee stock migrating past Tumwater Dam. Three-year-old fish were estimated to comprise 1% of the Bonneville Dam mixed-stock, 2% of the Okanogan stock and none of the Wenatchee stock. Six-year-old fish were estimated to comprise 4% of the Bonneville Dam mixed-stock, 13% of the Okanogan stock and <1% of the Wenatchee stock. For the first time in 17 years of CRITFC Columbia River sockeye salmon studies, sockeye salmon were estimated to have spent more than two years in freshwater. Sockeye spending greater than two years in freshwater were estimated to comprise 11% of the Okanogan Lake, 4% of the Bonneville Dam mixed-stock, and none of the Wenatchee stock. Scale pattern analysis techniques were used to estimate that 72% of the sockeye salmon passing Bonneville Dam were of Okanogan origin, 27% were of Wenatchee stock, with the remaining 1% of unknown origin.

Authors

Citation

Fryer, J.K. and D.A. Kelsey. 2003. Identification of Columbia Basin Sockeye Salmon Stocks Using Scale Pattern Analyses in 2002. Columbia River Inter-Tribal Fish Commission Report reference #03-02, Portland, Oregon. 36p.

Date

2003/04/20

Report No.

03-02

Media Type

CRITFC Technical Report