Joint Chinook Technical Committee. Estimates of Chinook Salmon Interceptions- A Report to the Joint Interceptions Committee. TCCHINOOK (90)-2. June 15, 1990

Executive Summary

In February of 1989, the Pacific Salmon Commission (PSC) established an Ad-Hoc Joint Interceptions Committee (JIC) in an attempt to narrow differences in salmon interception estimates exchanged by the United States and Canada one month earlier. A request was made to the Chinook Technical Committee to provide assistance in resolving differences in chinook salmon interceptions.

This report presents the Chinook Technical Committee's estimates of chinook salmon interceptions for the period 1981 through 1989. These estimates reflect an agreement on methodologies within the Chinook Technical Committee.

These estimates are primarily based on the PSC chinook model which was bilaterally developed to evaluate the impacts of management approaches on rebuilding of depressed chinook stocks. Since this model was not designed for the specific purposes of estimating stock compositions or estimating interceptions, a number of adjustments were required before model results could be applied. These adjustments are described on a fishery by fishery basis within the body of this report.

While the Committee reached agreement on the interception estimates presented in this report, concerns remain as to their accuracy, interpretation and potential use. The absolute magnitude of interceptions presented in this report should be viewed with caution since: (a) the accuracy of these estimates cannot be independently determined; (b) catches in some time and area strata for Canadian sport fisheries are not included; and (c) model stock composition estimates are not available for all catch strata. Interpretive notes pertaining to interception estimates for particular areas are provided for reference.

The Committee is confident that these estimates are consistent with our understanding of relative changes in stock status and appropriately reflect changes in interception patterns. The interception estimates presented in this report are considered the best available.