| Abstract/Description or Keywords |
The intent of this brief report is to describe the results of a stock-recruit analysis focused on Skeena lake sockeye CUs to develop benchmarks and evaluate status. This effort is part of a larger project to estimate benchmarks and status for all CUs in the Skeena watershed. Most of the methods and approaches used here will apply to other CUs in the Skeena, so a review of the analytical approach used for one species, where the data are relatively good, is a logical beginning. The first version of this report was released January 9, 2012. This version includes the following revisions and additions: 1) computation of an alternative lower benchmark, Sgen2, which is the escapement needed for the stock to recover to Smsy (the escapement that maximizes yield) in two generations; 2) correction of the two-fold overestimate of escapement data for Kiwtwancool between 2000 and 2010; 3) inclusion of most recent escapement data available for all CUs (this change only influences the time series plots of escapement but not the stock-recruit analysis as the recruitment estimates for these brood years are not yet available); 4) examination of residuals from the stock-recruitment curve over time to evaluate evidence for temporal trends in productivity; and 5) a more detailed analysis of the Babine Lake data (by stock group) to compare stock-recruitment curves for the aggregate and wild components. We evaluate whether the wild stock components have lower productivity than the aggregate, which is dominated by the production from spawning channels. These revisions address many of the questions outlined in a letter from the salmon committee of the marine conservation caucus on Feb. 27, 2012. Outstanding questions in this letter will be addressed at an upcoming workshop in Terrace. |
