Selection and application of a mark-and-recapture technique for estimating pink salmon escapements

Abstract

As part of a larger study to estimate straying rates of pink salmon (Oncorhynchus gorbuscha), escapements of pink salmon were estimated for eight streams in lower Chatham Strait, southeastern Alaska. Prior to stream sampling, computer simulations were used to compare stratified Schaefer and Petersen population estimators. The Petersen estimator was chosen for superior performance and used in conjunction with an efficient sampling design to calculate escapement for the eight streams. Live fish entering each stream were tagged with two opercular tags to account for tag loss, and streams were surveyed for tagged carcasses. Streams were sampled at least twice per week after fish were tagged. Petersen escapement estimates varied from 8,609 fish at William Creek to 79,070 fish at Deep Cove Creek, and all estimates had low coefficients of variation.


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