2007 Arctic Yukon Kuskokwim Sustainable Salmon Initiative Project Final Product Alternative methods for setting escapement goals in AYK 1

The escapement goals and management strategies for salmon stocks in the AYK region have been the subject of considerable controversy yet are critical in the management of these resources. It is widely recognized that there are limitations to the existing methods of creating brood tables and fitting Ricker or other stock-recruitment curves to these data, given the limited information for many AYK systems. In recent years there have been a number of new initiatives for evaluation of escapement goals, including methods that formally incorporate uncertainty and risk, habitat conditions, explicit analysis of life histories, use of data other than brood tables, understanding of stock structure and biocomplexity within watersheds, and evaluation of objectives other than maximum sustained yield. This project brought together a range of experts to evaluate the utility of these new methods for determining escapement goals for AYK stocks, assemble existing data relevant to calculation of AYK escapement goals, and to try to apply the new tools to several AYK systems. In this report, we present results from six activities. First, we provide a summary of existing data potentially useful for traditional escapement goal analyses, and a listing of all the technical reports in support of those data. In addition, CDs of the actual data are being supplied to AYK SSI staff. Second, we present a preliminary approach for assigning a metric to data quality so that data quality might be incorporated into future models. Third, we report on the reanalysis of productivity changes in three AYK salmon stocks, including three additional years of brood-year catch and escapement data. The reanalysis reinforced the conclusions from the 2004 analysis: all three stocks exhibit a strong downward, long-term trend in density-corrected recruits per spawner; and the strong year effects after correcting for both the trend and density show strong driving by some regional factor that affects all three stocks more or less synchronously. Fourth, we present a brief discussion of the potential effects of marine-derived nutrients on escapement goals. Fifth, we compare a new method of life-history-based modeling to outcomes of traditional spawner-recruit models. We find that escapement goals as determined by a life history approach are lower than escapement goals using a traditional Ricker analysis. Last, we present a preliminary overview of the kind of analysis that could eventually be useful for habitat-based estimates of spawning goals, by linking the total estimated rearing area of different types to the production rates for each habitat type.

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