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For clarity, only unpublished data (with the addition of the Red Lake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.