Figure 2. Yearly mean of δ15N and δ13C values (corrected for Suess effect) in scales of eight sockeye salmon stocks from Kodiak Island (Red Lake and Upper station), SE Alaska (Chillkat and Chilkoot), Columbia River (Okanagan and Wenachee) and Kamchatka Peninsula (Ozernaya and Kamchatka).
For clarity, only unpublished data (with the addition of the Red Lake stock) were represented in the Figure 2, however the assessment stands for all stocks (Table 1) with the absolute range being wider for δ15N than δ13C values, 5.05 vs 2.67, respectively. Significant correlation between δ15N and δ13C appeared random among stocks with no obvious pattern in region or age. A SI biplot of average values shows clear separation between the main regions despite the differences in time range covered (Figure 3). Kodiak Island and SE Alaska stocks together with Columbia River stocks showed lower δ15N and δ13C values. All Bristol Bay stocks grouped together with higher δ15N values, while Russian stocks and BC coast stocks were positioned between these aforementioned groups.