Overfishing, climate change linked with rising mercury levels in fish

Even as mercury levels in the oceans have fallen, levels in some fish—such as tuna, salmon, and swordfish—have increased due to overfishing and climate change, according to a new study.

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Harvard T.H. Chan School of Public Health found that overfishing has caused some fish to switch their prey to species with higher mercury levels. They also found that rising ocean temperatures have led to fish becoming more active and needing more food—and thus ingesting more mercury.

Mercury has been linked with impaired brain development and cognitive abilities and is especially dangerous for fetuses.

Climate change “is not just about what the weather is like in 10 years,” said Amina Schartup, who led the study while a researcher at SEAS and Harvard Chan School, in an August 7, 2019 article in The Atlantic. “It’s also about what’s on your plate in the next five.”

Senior author of the study was Elsie Sunderland, Professor of Environmental Science and Engineering in the Department of Environmental Health and a professor of environmental chemistry at SEAS.

Read the Atlantic article: Some Fish Are Still Full of Mercury, for a Worrying Reason

Read an NBC News article: Climate change and overfishing could lead to higher mercury levels in fish

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Seafood, Mercury, & Health (Center for Climate, Health, and the Global Environment)