|Document Type:||Contract Report|
|Title:||Relative survival estimates for PIT-tagged juvenile chinook salmon passing through turbines, collection channels, and spillways at Ice Harbor Dam, 2003|
|Author/Editor:||R. F. Absolon, Benjamin P. Sandford, M. B. Eppard, Dean A. Brege, Kenneth W. McIntyre, Eric E. Hockersmith, Gene M. Matthews|
|Publisher:||National Marine Fisheries Service|
|Contracting Agency:||U.S. Army Corps of Engineers. Walla Walla, Washington|
For this study, we had two objectives. The first was to evaluate relative survival of yearling hatchery Chinook salmon Oncorhynchus tshawytscha released into the collection channel and two turbine units at Ice Harbor Dam. This evaluation was conducted with river-run hatchery yearling Chinook salmon collected and PIT tagged at Little Goose Dam. At Ice Harbor Dam, releases were made to the collection channel, to turbine slots 1A and 3A, and to the tailrace about 1 km downstream from the dam. A total of 37 releases were made, with about 350 fish in each release group. For hatchery yearling Chinook salmon, point estimates of relative survival through the turbines and collection channel were 0.871 and 0.975, respectively. Relative survival through individual turbines was estimated at 0.888 for turbine unit 1A and 0.855 for turbine unit 3A.
The second objective was to evaluate relative survival of hatchery subyearling Chinook salmon released to the spillway, collection channel, and a turbine unit. This evaluation used river-run hatchery subyearling Chinook salmon collected and PIT tagged at Lower Monumental Dam. Twenty-four releases of approximately 525 fish per group were made at Ice Harbor Dam, with groups released into spillway slots 2-4, into the collection channel adjacent to turbine slot 6B, into turbine slot 1A, and into the tailrace about 1 km downstream from the dam. Releases were made in alternating 2-d blocks of spill and no spill, and spill volume was distributed among 2-3 spillbays (bulk pattern) rather than evenly across the spillway (BiOp pattern).
Point estimates of relative survival for hatchery subyearling Chinook salmon released into turbine units, the spillway, and the collection channel were 0.893, 0.964, and 0.997, respectively. Relative survival of subyearling Chinook salmon through spillways was estimated at 0.964 under the bulk spill pattern; this was higher than the estimates obtained in 2000 (0.885) and 2002 (0.894) under the BiOp spill patterns.