Compliance Monitoring of Juvenile Yearling Chinook Salmon and Steelhead Survival and Passage at the Dalles Dam, Spring 2011. Revised May, 2012.

摘要

The purpose of this compliance study was to estimate dam passage survival of yearling Chinook salmon and steelhead smolts at The Dalles Dam during spring 2011. Under the 2008 Federal Columbia River Power System Biological Opinion, dam passage survival is required to be greater than or equal to 0.96 and estimated with a standard error (SE) less than or equal to 0.015. The study also estimated smolt passage survival from the forebay 2 km upstream of the dam to the tailrace 2 km below the dam, as well as forebay residence time, tailrace egress time, and spill passage efficiency (defined below), as required in the Columbia Basin Fish Accords. A virtual/paired-release design was used to estimate dam passage survival at The Dalles Dam. The approach included releases of acoustically tagged smolts above John Day Dam that contributed to the formation of a virtual release at the face of The Dalles Dam. A survival estimate from this release was adjusted by a pair of releases below The Dalles Dam. A total of 4,258 yearling Chinook salmon and 4,336 steelhead smolts were used in the virtual releases. Sample sizes for the below-dam paired releases were 799 and 799 for yearling Chinook salmon smolts and 800 and 800 for steelhead smolts. The Juvenile Salmon Acoustic Telemetry System tag (ATS-156dB), weighing 0.438 g in air, was used.