|Document Type:||Contract Report|
|Title:||Passage and survival of hatchery yearling Chinook salmon at McNary Dam, 2003|
|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 2003, NOAA Fisheries continued the second year of a study to determine passage distribution and dam survival for radio tagged, river run, hatchery yearling chinook salmon passing McNary Dam on the Columbia River. Fish were collected, PIT tagged, and a radio transmitter was gastrically implanted. We released fish in the spillway and tailrace of Lower Monumental Dam, in the tailrace of Ice Harbor Dam, and into the Columbia River approximately 15 km upstream from its confluence with the Snake River to compare fish passage metrics for fish originating from each river. Releases occurred during the daytime on 26 days from 29 April to 6 June.
Approach path and subsequent passage route appeared to be related to delay time in the forebay. Further analysis demonstrated a statistical difference between spilled fish and bypassed fish in their associated forebay delay, with median delay times of 0.5 and 1.2 h, respectively (P <0.002). Overall passage distribution for Snake River fish through spillway, bypass, and turbine routes at McNary Dam was 46, 46, and 5%, respectively. Passage distribution for Columbia River fish through spillway, bypass, and turbine routes at McNary Dam was 48, 45, and 4%, respectively. Fish passage efficiency was similar between Snake and Columbia River fish at 95 and 96%, respectively. Overall fish guidance efficiency for Snake and Columbia River fish was 90 and 91%, respectively. Spill efficiency was 47% for Snake River fish and 49% for Columbia River fish. Mean spill effectiveness for Snake River migrants was 1.43:1 compared to 1.32:1 for Columbia River migrants.
Dam survival was estimated from detections of fish in the forebay of McNary Dam to Irrigon, 12 km downstream. Estimated survival through this reach was 0.893 (95% CI, 0.849 0.937). Spillway passed fish survival to Irrigon was 0.928 (95% CI, 0.874 0.892). The survival rate to Irrigon of those passing the juvenile bypass system was 0.865 (95% CI, 0.803 0.927). Not enough fish passed through turbine routes to estimate turbine survival.