Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 8885
Title: An assessment of freeze–brand and PIT–tag recovery data at McNary Dam,1987
Author/Editor: Clinton Scott McCutcheon, Albert E. Giorgi
Publication Year: 1989
Publisher: National Marine Fisheries Service
Contracting Agency: Bonneville Power Administration. Portland, Oregon

This study evaluated mark recovery data from PIT-tagged and freeze–branded fish recovered at McNary Dam in 1987.  Hatchery and river–run populations of yearling Chinook salmon Oncorhynchus tshawytscha, sockeye salmon O. nerka and steelhead O. mykiss were used in this investigation.  Paired groups of PIT-tagged and freeze–branded juvenile salmonids were released upstream from McNary Dam and subsequently recaptured at that site.  PIT tags were recovered in significantly higher proportions than freeze brands regardless of species or stock.  Furthermore, for Chinook and sockeye salmon, PIT tag recovery data exhibited less variability.  Reasons for the discrepant intermark recovery rates are discussed.