Is fish at the grocery store getting cleaner or dirtier on mercury?

What's actually in it

Methylmercury builds up in fish that eat other fish. Bigger and longer-lived fish carry more. Swordfish, shark, king mackerel, and tilefish are the highest. Sardines, salmon, and shrimp are among the lowest.

Coal-fired power plants and gold mining are the main mercury sources. Cleaner power has helped, but ocean mercury moves slowly, so fish levels haven't changed much.

What the research says

A 2026 study in Environ Res ran a Bayesian analysis of mercury in fish from 2011 to 2021. Average mercury levels stayed flat. Some species like albacore tuna trended slightly higher; some bottom-dwelling fish trended slightly lower. The overall picture: shopping advice from 2011 still holds.

The team flagged that pregnant women, kids, and frequent fish eaters need to keep watching the species list, not just "eat fish."

Pick salmon, sardines, anchovies, shrimp, trout, and pollock for low mercury. Limit albacore tuna to once a week. Skip swordfish, shark, king mackerel, and tilefish in pregnancy and for kids under 12.