An Assessment of Freeze Brand and Pit Tag Recovery Data at McNary Dam, 1987




chinook, freeze branding, hatchery, juvenile, McNary Dam, Oncorhynchus tshawytscha, PIT tag, salmon, salmonids, sockeye salmon, steelhead, upstream


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.

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