Figure 5. Estimated feeding grounds during the last summer at sea of (a) Wood River, (b) Togiak, (c) Nugashak, (d) Igushik, (e) Naknek, (f) Kvichak, (g) Egegik and (h) Ugashik sockeye salmon stocks (Bristol Bay from north to south). Strongest correlation coefficient between SST and δ13C value is indicated by a white cross. Locations of the point of entry in the freshwater system of the different stocks is shown (red circle).
Correlation coefficients were relatively less significant for the Bristol Bay stocks, most likely because of the every 3-year sampling resolution that resulted in a low number of data points that did not capture the full extent of interannual variability. No smoothing was applied to the SI values because of the coarse resolution but smoothing the SST series resulted in a slight improvement in the defined areas. Both Russian stocks showed similar at-sea distributions despite originating from opposite side of the Kamchatka Peninsula (Figure 6). Smoothed time series provided more significant correlations for these stocks.