Stable Isotope Ratios of Carbon and Nitrogen and Mercury Concentrations in 13 Toothed Whale Species Taken from the Western Pacific Ocean off Japan

Stable isotope ratios of carbon (∂13C) and nitrogen (∂15N) and total mercury (T-Hg) concentrations were measured in red meat samples from 11 odontocete species (toothed whales, dolphins, and porpoises) sold in Japan (n = 96) and in muscle samples from stranded killer whales (n = 6) and melon-headed whales (n = 15), and the analytical data for these species were classified into three regions (northern, central, and southern Japan) depending on the locations in which they were caught or stranded. The ∂15N in the samples from southern Japan tended to be lower than that in samples from the north, whereas both ∂13C and T-Hg concentrations in samples from the south tended to higher than those in samples from northern Japan. Negative correlations were found between the ∂13C and ∂15N values and between the ∂15N value and T-Hg concentrations in the combined samples all three regions (γ= −0.238, n = 117, P < 0.01). The ∂13C, ∂15N, and T-Hg concentrations in the samples varied more by habitat than by species. Spatia...