Stable isotope ratios and mercury levels in red meat products from baleen whales sold in Japanese markets.
ABSTRACT We analyzed the δ(13)C, δ(15)N and δ(18)O values and Hg concentration in red meat products originating from the predominant types sold in Japan for human consumption: two populations of common minke (J- and O-types), Bryde's and sei whales in the western North Pacific Ocean, and fin and Antarctic minke whales in the Southern Ocean. The order of the trophic positions, evaluated by δ(15)N values and Hg concentrations, coincided with their known feeding habits: common minke (J-type)=common minke (O-type)> Bryde's ≥ sei ≥ Antarctic minke ≥ fin. The Hg concentrations in the combined samples from the six samples were significantly correlated with their δ(15)N values (γ=0.455, n=66, p<0.05), reflecting overall differences in the trophic level. This correlation was not significant for within-species comparison for the common minke (J- and O-types) or the Bryde's whale, probably reflecting the higher δ(15)N value and lower Hg concentration in the North Pacific Ocean around Japan. Determination of δ(13)C, δ(15)N and δ(18)O could be used to discriminate between the red meat products originating from the whale species in the North Pacific and Southern Oceans. However, the four whale species or populations in the Pacific Ocean could not be discriminated on basis of these values, nor could the two species in the Southern Ocean. Positive correlations between the δ(13)C and δ(15)N values and negative correlations between the δ(15)N and δ(18)O values and the δ(13)C and δ(18)O values, probably reflecting migration patterns, were found in some whale species in the North Pacific and Southern Oceans.