Stock-specific stable isotope values
Large interannual variations were observed for both δ13C and δ15N (Figure 2). Stocks that are in close geographic proximity showed similar patterns in SI values variability at low frequency but their SI values can differ substantially over small temporal scale. Suess effect-corrected δ13C values showed more stability over time than δ15N and also less variation between stocks with values mainly distributed between -19 to -17.5‰ while δ15N values spanned over 3‰ (8.5 to 11.5‰).