Survival estimates for the passage of juvenile salmonids through Snake River dams and reservoirs, 1996

Publication Date



Report Prepared by the U.S. National Marine Fisheries Service, Northwest Fisheries Science Center for the Bonneville Power Administration


survival, survival estimates, juvenile, salmonids, Snake River, dams, reservoirs, University of Washington, smolt, Lower Granite Reservoir, transponder, downstream migration, migration, PIT tag, Bonneville Dam, models, releases, hatchery, steelhead, chinook, salmon, Lower Granite Dam, environmental conditions, travel time, environmental factors

Report number

Report No. DOE/BP-10891-5


In 1996, the National Marine Fisheries Service and the University of Washington completed the fourth year of a multi-year study to estimate Survival of juvenile salmonids (Oncorhynchus spp.) passing through dams and reservoirs on the Snake River.Actively migrating smolts were collected near the head of Lower Granite Reservoir and at Lower Granite Dam, tagged with passive integrated transponder (PIT) tags, and released to continue their downstream migration. Individual smolts were subsequently detected at PIT-tag detection facilities at Lower Granite, Little Goose, Lower Monumental, McNary, John Day and Bonneville Dams. Survival estimates were calculated using the Single-Release (SR) and Paired-Release (PR) Models. Timing of releases of tagged hatchery steelhead (O. mykiss) from the head of Lower Granite Reservoir and yearling Chinook salmon (O. tshawytscha) from Lower Granite Dam in1996 spanned the major portion of their juvenile migrations. Specific research objectives in 1996 were to 1) estimate reach and project survival in the Snake River using the Single-Release and Paired-Release Models throughout the yearling Chinook salmon and steelhead migrations, 2) evaluate the performance of the survival-estimation models under prevailing operational and environmental conditions in the Snake River, and 3) synthesize results from the 4 years of the study to investigate relationships between survival probabilities, travel times, and environmental factors such as flow levels and water temperature.

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