Identification of Columbia Basin Sockeye Salmon Stocks Using Scale Pattern Analyses in 2000

AUTHORS:	Jeffrey K. Fryer |  Denise A. Kelsey
PUBLICATION DATE:	30 May 2001
REPORT #:	01-2

ABSTRACT:
In 2000, representative 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. These locations 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 for all samples was estimated. Four-year-old fish were estimated to comprise approximately 95% of the Bonneville Dam mixed-stock, 87% of the Okanogan known-stock (collected at Wells Dam), and 99% of the Wenatchee known-stock samples. Five-year-old fish were estimated to comprise approximately 1% of the Bonneville Dam mixed-stock, 5% of the Okanogan stock, and 1% of the Wenatchee stock samples. Three-year-old fish were estimated to comprise approximately 4% of the Bonneville Dam mixed-stock, 7% of the Okanogan stock, and 0% of the Wenatchee stock samples. Scale pattern analysis techniques were used to estimate that 56% of the Age 1.2 sockeye salmon, and 55% of the entire run, passing Bonneville Dam were of Okanogan stock, with the remainder of Wenatchee stock.

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