Patterns in Productivity of Alaskan Chinook Salmon Stocks

Temporal patterns in total life-cycle productivity were evaluated for fifteen Alaskan Chinook salmon stocks to assess temporal trends in productivity, the degree to which productivity trends were shared, and the functional form of compensatory density dependence.  The most recent abundance estimates for 13 of the 15 stocks are at or near the lowest on record.  Productivity (ln R/S residuals) was positively correlated among western Alaska stocks although some correlations were weak. Correlations in productivity among southeast Alaska stocks were weaker and more variable than stocks of the other regions, and correlations with stocks in other regions were weak.  A regression analysis revealed a weak but statistically-significant negative relationship between ln R/S residual correlations and between-stock distance, which indicated that regional scale environmental factors likely explain a relatively small proportion of the temporal variation in productivity.  Evidence for over-compensatory stock-recruitment dynamics was tested by comparing the relative degree of empirical support for the Beverton-Holt vs. Ricker stock recruitment models using Bayesian parameter inclusion probabilities.  The over-compensation hypothesis (Ricker model) was strongly supported for the Kuskokwim River Chinook stock, but weakly supported for the other 14 stocks.