Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 5465
Title: Evaluation of juvenile fall chinook salmon passage through the McNary Dam juvenile fish bypass system to identify areas of delay
Author/Editor: Gordon A. Axel, Richard W. Zabel, Benjamin P. Sandford, Douglas B. Dey
Publication Year: 2002
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Walla Walla, Washington
Contract Number: W68SBV10182878
Date: 2002

In 2001, we completed the second year of a study to evaluate travel times of juvenile subyearling chinook salmon Oncorynchus tshawytscha in the bypass system at McNary Dam.  The first year of study indicated a delay associated with passage through the juvenile fish bypass system:  median residence time within the Unit 8A gatewell was 2.8 h.  During 2001, radiotelemetry receivers were deployed to determine areas of delay within the gatewell, collection channel, and separator.

River-run subyearling chinook salmon were collected and radio tagged at the McNary Dam juvenile fish collection facility.   A total of 262 tagged fish were released into the gatewells of three turbine units and monitored as they traversed the bypass system.

All 261 radio-tagged fish were detected as they passed through the bypass system and exited the separator.  Median residence time was 8.6 h in gatewell 8A, 2.6 h in gatewell 10A, and 3.7 h in gatewell 13A.  Gatewell residence accounted for 90-98% of total travel time through the juvenile bypass system.