Stable isotope ratios of carbon, nitrogen and oxygen in killer whales (Orcinus orca) stranded on the coast of Hokkaido, Japan

摘要

We analyzed δ~(13)C, δ~(15)N and δ~(18)O in the muscle and liver from killer whales stranded on the coast of Japan. The δ~(15)N values in the muscle samples from calves were apparently higher than those in their lactating mothers, suggesting that nursing may result in the higher δ~(15)N values in the muscle samples of calves. The δ~(15)N value in the muscle samples of male and female whales, except for the calves, were positively correlated with the δ~(13)C values and body length, suggesting that the increases in δ~(15)N were due to the growth of the whales and increase in their trophic level. In contrast, the δ~(18)O values in the muscle samples of female whales except for the calves were negatively correlated with the δ~(13)C and δ~(15)N values. The δ~(18)O may be lower in whales occupying higher trophic positions (δ~(15)N), although it might also be affected by geographic and climatic conditions.