Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 7018
Title: Lower Granite pool and turbine survival study, 1987
Author/Editor: Albert E. Giorgi, Lowell C. Stuehrenberg
Publication Year: 1988
Publisher: National Marine Fisheries Service
Contracting Agency: Bonneville Power Administration. Portland, Oregon
Contract Number: DE-AI79-87BP34270
Date: 1988

Survival of yearling spring chinook salmon was estimated as they traversed Lower Granite Reservoir and passed through a turbine at Lower Granite Dam.  Fish were PIT tagged at Rapid River Hatchery and transported to release sites near Asotin, Washington, and at Lower Granite Dam.  Recovery ratios of treatment and control groups were used to estimate survival.  Estimates were based on tags intercepted at both Lower Granite and Little Goose Dam.  Turbine survival was estimated to be 83.1% (95% Cl 74.1–92.2%).  A qualified estimate of survival from Asotin to Lower Granite Dam for a single release group was calculated as 71.9%.  Uncertainties associated with satisfying certain key mark and recapture statistical assumptions are examined.  As a result of these uncertainties, an alternate study design and analytical procedure are recommended for future investigations.