Survival estimates of migrant juvenile Salmonids through Bonneville Dam using radio telemetry, 2004

During 2004, the USGS evaluated the survival of radio-tagged yearling and subyearling Chinook salmon and steelhead trout through the ice and trash sluiceway and the minimum gap runner (MGR) turbine unit at Bonneville Dam’s powerhouse 1. Survival was estimated using paired release-recapture models with paired releases made directly into these passage routes and in the tailrace of Bonneville Dam. For the evaluations of survival through the MGR two separate control release locations were used; one location was directly downstream of the front roll below the turbine unit and the other release location was further downstream of the powerhouse 2 juvenile bypass outfall. During spring and summer releases of radio-tagged fish into the MGR and the ice and trash sluiceway, powerhouse 1 was not continuously operated due to a policy that prioritized the passage of water through powerhouse 2. Because of this policy, powerhouse 1 was only operated sporadically for short time intervals before and after the releases of radiotagged fish associated with this study.