Eating dolphin meat may seem abhorrent to most Americans, but many cultures around the world include marine mammals in their diets. For instance, people on the tropical island of St. Vincent in the Caribbean can legally hunt and eat dolphins. But these culinary traditions have a health downside: The meat and blubber contain high levels of mercury, which can contribute to disorders ranging from memory loss to seizures.

Much of the mercury pollution in the ocean comes from gold mining. Once in the water, it can be converted to another chemical called methylmercury. Small organisms ingest the mercury and methylmercury; when predators eat those animals, they accumulate even higher levels of the toxic compounds. Because marine mammals are near the top of the food chain, they often carry the most mercury in their tissues.

Researchers studied dolphin consumption in St. Vincent, where about two-thirds of the residents eat marine mammal meat. The team members analyzed meat and blubber from 28 spinner dolphins and 11 Atlantic spotted dolphins that had been caught near the island. They also tested processed unidentified cetacean meat, probably from dolphins or pilot whales, from a market. People usually process the meat by cutting it into pieces and drying it to make a beef jerky-like snack.

The fresh, unprocessed tissue contained an average of 0.92 to 1.57 micrograms of mercury per gram, the researchers report in Marine Pollution Bulletin. The U.S. Food and Drug Administration considers 1 microgram per gram to be the “action level” at which authorities could advise people to cut down on seafood consumption. And the processed meat was far worse — it contained an average of 7.59 micrograms of mercury and 6.05 micrograms of methylmercury per gram of tissue.

The results suggest that dolphin meat could pose a health risk to the people of St. Vincent, the team suggests. If public health officials advise residents to eat less of it, dolphin populations could benefit — but managers will need to make sure that substituting other meats doesn’t create another conservation problem. — Roberta Kwok | 6 November 2014

Source: Fielding, R. and D.W. Evans. 2014. Mercury in Caribbean dolphins (Stenella longirostris and Stenella frontalis) caught for human consumption off St. Vincent, West Indies. Marine Pollution Bulletin doi: 10.1016/j.marpolbul.2014.10.040.

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