Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 6534
Title: Passage behavior and survival of hatchery yearling Chinook salmon passing Ice Harbor and McNary Dams during a low flow Year, 2001
Author/Editor: Gordon A. Axel, Eric E. Hockersmith, M. B. Eppard, Benjamin P. Sandford, Steven G. Smith, Douglas B. Dey
Publication Year: 2003
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Walla Walla, Washington
Contract Number: W68SBV92844866
Pages: 35
Date: 08/01/2003

In 2001, we conducted research to evaluate survival and approach and passage behavior at Ice Harbor Dam for river run hatchery yearling chinook salmon Oncorhynchus tshawytscha.  This study took place during a drought year, resulting in no spill at dams like Ice Harbor Dam, which have no holding raceways for transporting fish.  Specific goals were of the research were:

  1. to estimate project and bypass survival through Ice Harbor Dam,
  2. to estimate survival through partitioned reaches between Ice Harbor and McNary Dam,
  3. to evaluate approach and passage behavior at Ice Harbor and McNary Dam, and
  4. to compare methodologies (PIT tag vs. radiotelemetry) for use in estimating survival.

Study fish were collected at Lower Monumental Dam, tagged either with a PIT tag or with both a radio transmitter and a PIT tag, and released 5.0 km upstream from Ice Harbor Dam or into the juvenile bypass outfall pipe just downstream from the Ice Harbor Dam smolt monitoring facility.  Reach survival was estimated from detections at radiotelemetry receiver transects located in the forebay and tailrace of Ice Harbor Dam, Strawberry Island, Sacajawea Park at the mouth of the Snake River, Port Kelley, McNary Dam, and at the mouth of the Umatilla River.  Tagging methodologies were compared using PIT tag detections from McNary, John Day, and Bonneville Dams and from detections in a surface trawl detection system operated in the estuary.

Project survival through Ice Harbor Dam, from the forebay to Strawberry Island, was 0.936 for radio tagged hatchery yearling chinook salmon.  Estimated survival to McNary Dam for fish released 5 km upstream from Ice Harbor Dam was 0.744 for radio-tagged fish and 0.724 for PIT-tagged fish.  Estimated survival from the Ice Harbor juvenile bypass system to Strawberry Island was 0.996 for radio tagged fish released 5 km upstream from Ice Harbor Dam.  Estimated survival to McNary Dam for radio tagged fish released into the bypass outfall pipe at Ice Harbor Dam was 0.801.

For radio tagged yearling chinook salmon, residence time in the Ice Harbor forebay was longer in 2001 (7.3 h) than in 1999 (1.3 h), which was considered a normal flow year with spill at Ice Harbor Dam.  Median tailrace egress was 9.3 min overall, 9.0 min for fish passing through the juvenile fish bypass system, and 14.7 min for fish passing through a turbine unit.

Estimated survival for PIT tagged fish between the forebays of Ice Harbor and McNary Dam was 0.724, similar to the estimate of 0.744 for radio-tagged fish.  This work demonstrated that under these conditions, the two tagging methodologies can obtain similar survival estimates.  However, because of exceptionally low river flows during 2001, we recommend that environmental conditions be considered when interpreting the results of this study.  We also recommend that the Caspian tern colony on Crescent Island be evaluated annually to determine consumption rates and overall effects on Snake River salmonids.