|Document Type:||Contract Report|
|Title:||Passage behavior and survival of radio-tagged yearling and subyearling Chinook salmon and juvenile steelhead at Ice Harbor Dam, 2008|
|Author/Editor:||Gordon A. Axel, Eric E. Hockersmith, Brian J. Burke, Kinsey E. Frick, Benjamin P. Sandford, William D. Muir, R. F. Absolon|
|Publisher:||National Marine Fisheries Service|
|Contracting Agency:||U.S. Army Corps of Engineers. Walla Walla, Washington|
In 2008, we evaluated passage behavior, distribution, and survival of yearling Chinook salmon, steelhead, and subyearling Chinook salmon at Ice Harbor Dam. A central objective of these evaluations was to determine the effects of a removable spillway weir (RSW) used during two different spill operations.
Study fish were collected and surgically tagged with both a radio transmitter and PIT tag at Lower Monumental Dam. For the Ice Harbor evaluation, treatment groups consisted of fish released either 42 km above or into the tailrace of Lower Monumental Dam. These fish were regrouped by day of detection on the Ice Harbor forebay entry line, 600 m upstream from the dam. A total of 1,699 yearling Chinook, 1,951 juvenile steelhead, and 2,314 subyearling Chinook were evaluated.
Yearling Chinook salmon—Passage survival was estimated at 0.966 (0.953-0.978) through the spillway, 0.953 (0.927-0.979) through the RSW, and 0.925 (0.905-0.944) through the dam. Survival was estimated at 0.977 (0.954-1.000) through the juvenile bypass system and 0.943 (0.889-0.996) through the turbines. Concrete survival, or the survival estimate for all fish that passed the project, was 0.966 (0.955-0.978).
Juvenile Steelhead—Passage survival was estimated at 0.973 (0.962-0.985) for the spillway, 0.970 (0.954-0.986) for the RSW, 0.971 (0.947-0.996) for the juvenile bypass system, and 0.927 (0.909-0.946) for the dam. Concrete survival was 0.970 (0.959-0.981). Insufficient numbers of tagged fish (22) passed through the turbines to estimate survival.
Subyearling Chinook salmon—Passage survival was estimated at 0.942 (0.926 0.958) through the spillway, 0.920 (0.891-0.948) through the RSW, and 0.862 (0.846 0.878) through the dam. The estimate for bypass survival was 0.929 (0.903-0.956), while turbine survival measured 0.778 (0.685-0.870). Concrete survival was 0.933 (0.919-0.947).