Mercury in Seafood — FDA Data

The FDA's action level is 1.0 ppm. Fish exceeding this can be removed from commerce. In this dataset, Gulf of Mexico tilefish (1.123 ppm), swordfish (0.995 ppm), and shark (0.979 ppm) meet or approach this threshold. The action level is a regulatory enforcement tool — the EPA reference dose for risk assessment implies a lower safe intake for sensitive populations, particularly pregnant women.

Plant based omega-3 sources contain zero mercury. Flaxseeds, chia seeds, walnuts, and hemp seeds provide ALA with no methylmercury exposure. Algae-derived DHA and EPA supplements provide the same long-chain omega-3s found in fish — since fish accumulate DHA/EPA from algae in the first place — without any contamination. This makes algae oil the safest and most direct source of marine-type omega-3s.

No. Cooking does not meaningfully reduce methylmercury. It is tightly bound to fish muscle proteins and is not destroyed or leached by boiling, frying, baking, or grilling. The only way to reduce exposure is to choose lower-mercury species or replace seafood with plant based or algae-derived omega-3 sources.

Generally yes for predatory species, but it depends on the feed. Farmed salmon often has lower mercury than wild predatory fish because controlled feed limits exposure. Species like tilapia, catfish, and trout are low-mercury regardless of whether farmed or wild. For top predators like tuna, wild-caught and farmed levels are similar because mercury accumulates via feed anyway.

A whole-food plant based diet essentially eliminates dietary methylmercury exposure. Methylmercury enters the human food supply almost exclusively through fish and shellfish. Research consistently shows that people who eat no fish have significantly lower blood mercury levels than regular fish consumers. Some plant foods grown in contaminated soil may contain trace inorganic mercury, but at levels orders of magnitude lower than high-mercury fish.