Researchers Find Mercury in Deep Ocean Fish
Posted on | September 4, 2009 | No Comments
Mānoa researchers, graduate student Anela Choy, Professor Brian N. Popp and Assistant Professor Jeffrey C. Drazen, examining mercury levels in pelagic fish in Hawaiʻi found that fish that hunt deeper in the open ocean have higher mercury concentrations than those that feed near the surface of the ocean because their deep water food has higher mercury. The study was published in the Proceedings of the National Academy of Sciences.
Mercury is a naturally-occurring trace element distributed throughout the Earth’s oceans, land and air. The general public is interested in mercury levels in fish because the organic form, methylmercury, can be toxic at elevated levels if ingested by humans and animals. Mercury enters open ocean food webs, where it bioaccumulates, leading to higher levels in large predatory animals.
Researchers looking at mercury levels in the open ocean have indicated that deeper waters have elevated levels relative to the surface waters. "Building on this information, we thought that deeper-dwelling open ocean animals might have more mercury, as well as the predatory fishes that feed on them," says lead author Choy. The results of their work show that large pelagic fish like bigeye tuna and swordfish that feed deeper in the ocean have elevated total mercury levels relative to their shallower-dwelling counterparts like yellowfin tuna and mahi mahi.
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