By Ben Harder
Hunting and consumption of marine mammals continues in Japan despite an international moratorium on commercial whaling. People there who eat dolphins and other toothed whales are ingesting whopping amounts of the metal mercury, new data suggest.
Tetsuya Endo of the Health Sciences University of Hokkaido and his colleagues measured the mercury content of nearly 200 meat samples collected from vendors or processors of the marine mammals.
The researchers determined that 137 of the samples came from nine species of toothed whales, including false killer whales, pilot whales, and several species of dolphins and porpoises. Another 62 samples came from six species of baleen whales, which eat tiny organisms filtered from water by comb-like mouth structures.
Average mercury concentrations for individual species of toothed whales ranged from 1.3 to 46.9 micrograms per gram (g/g) of meat. Every sample exceeded 0.4 g/g, the maximum allowable mercury concentration in foods in Japan.
Unlike toothed whales, baleen whales eat organisms that may be too low on the food chain to accumulate much mercury. Only one meat sample from a baleen whale exceeded the allowable mercury concentration, the researchers report in the June 15 Environmental Science and Technology. Other reports have suggested that since the 1986 moratorium on whaling, toothed whales have contributed a larger fraction of the whale meat consumed in Japan.
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