|Document Type:||Contract Report|
|Title:||Passage and survival of hatchery yearling Chinook salmon at McNary Dam, 2002|
|Author/Editor:||Gordon A. Axel, Eric E. Hockersmith, M. B. Eppard, Benjamin P. Sandford|
|Publisher:||National Marine Fisheries Service|
|Contracting Agency:||U.S. Army Corps of Engineers. Walla Walla, Washington|
In 2002, we evaluated passage distribution, project survival, and route-specific survival for radio-tagged, river-run, hatchery yearling chinook salmon passing McNary Dam on the lower Columbia River. Fish were collected, PIT tagged, and surgically implanted with a radio transmitter. We released 1,607 radio-tagged fish to the spillway and tailrace of Ice Harbor Dam on the lower Snake River. Releases occurred during daytime and nighttime operations over 31 d, from 5 May to 5 June.
Overall passage distributions for radio-tagged Snake River hatchery yearling chinook salmon through spillway, bypass, and turbine routes at McNary Dam were 45, 46, and 4%, respectively, with approximately 5% of fish having undetermined passage routes. Fish passage efficiency was 96%. Overall fish guidance efficiency was 93%. Spill efficiency was 47%, and mean spill effectiveness was 1.12:1.
Project survival was estimated from the forebay of McNary Dam to the downstream telemetry transect at Irrigon, OR on the lower Columbia River. Estimated project survival was 0.877, spillway passage survival was 0.976, and the bypass outfall survival estimate was 0.927.
Analysis of tailrace egress identified a statistically significant difference between median egress times for spilled fish (5.5 min) and bypassed fish (10.2 min; P <0.001). In diel comparisons there was also a statistically significant difference in tailrace egress times between fish bypassed during the day (9.4 min) and those at night (11.4 min; P <0.001).