Use of stable isotopes to distinguish farmed from wild Atlantic salmon, <i>Salmo salar</i>

Abstract

Abstract – Stable isotopes of carbon and nitrogen ( δ 13 C and δ 15 N) were examined in wild and aquaculture origin Atlantic salmon, Salmo salar , to evaluate their utility to identify escaped farmed fish. Samples of muscle tissue obtained from wild Conne River, Newfoundland, salmon were significantly more enriched in nitrogen ( δ 15 N: mean = 12.75; SD ± 0.38‰) but depleted in lipid corrected carbon ( δ 13 C′: mean = −20.51; SD ± 0.23‰) by comparison with aquaculture specimens obtained from Bay d'Espoir, Newfoundland ( δ 15 N = 10.96 ± 0.19‰; δ 13 C′ = −19.25 ± 0.17‰) resulting in a complete separation of the two groups. Aquaculture specimens differed in δ 13 C′ from analyses of commercial salmon diet by 0.24‰, within the enrichment range associated with trophic transfers, while the δ 15 N values in salmon muscle were enriched by 5.01‰. Although differences occurred in direct comparisons of white muscle and adipose tissue ( N = 49), the average δ 13 C′ and δ 15 N signatures varied in absolute amounts by only 0.5‰, supporting the use of adipose tissue as a nonlethal means to determine isotopic signatures of Atlantic salmon.