Shrnutí

Popis

Codedwiretags CWT and passive integrated transponder PIT tags are usedextensively throughout the Columbia River Basin to address a wide variety of management andresearch questions. A recent study by Knudsen et al. 2009 found that dualtagged CWT andPITtagged hatchery spring Chinook salmon smolts released in the Yakima River had lowersmolttoadult return rates SARs compared to CWT smolts, indicating that PITtags mayimpart a survival bias relative to smolts tagged with CWTs. Given the widespread use of CWTand PITtags, further evaluations of potential tag effects would be informative for quantifying thelevel of bias, if present, associated with each of these two tag types. Towards this end, weinitiated the PITTag Effects Study PTES at Carson National Fish Hatchery NFH with themarking of the brood year 2009 release. The objectives are 1 to determine the effects of PITtagson spring Chinook salmon SARs and 2 to determine PITtag loss rates throughout thecomplete salmon lifecycle.