Mercury Levels in Different Fish and Shellfish

See this related seafood lobby fable:
Fable: All fish are alike; there are no “good fish” or “bad fish”

Different fish and shellfish varieties contain widely different average mercury levels. A person’s mercury exposure depends on two factors: How much fish one eats, and which fish one eats. This critical fact is often obscured by industry exhortations to “eat more fish,” without regard to mercury content. Such indiscriminate advice implies another important fable:

Fable: All fish are alike; there are no “good fish” or “bad fish.”

Facts: Fish are definitely not all alike. Different popular fish varieties differ in their content of certain beneficial nutrients, and vary in average mercury content by more than 100-fold.

For people who would like to estimate their own mercury exposure based on the types and amounts of fish they eat, a table giving FDA data on the mercury content of 51 different fish and shellfish varieties.

Most fish and shellfish—and a large majority of the varieties eaten in greatest volume by Americans—are quite low in mercury and pose little risk, even for people who eat them often. The table below lists the top ten seafood items in sales in the US in 2005 through 2007 (data from the National Fisheries Institute). Actually there are 11 items in the “Top 10,” because scallops replaced flatfish in 10th place in 2006.

Top Ten US Seafood Choices, 2005-2007 (NFI 2008)

Rank Variety 2005 Variety 2006 Variety 2007
Per capita consumption, pounds per year
1 Shrimp 4.10 Shrimp 4.20 Shrimp 4.10
2 Canned tuna 3.10 Canned tuna 2.90 Canned tuna 2.70
3 Salmon 2.43 Salmon 2.03 Salmon 2.36
4 Pollock 1.47 Pollock 1.64 Pollock 1.73
5 Catfish 1.03 Tilapia 1.00 Tilapia 1.14
6 Tilapia 0.85 Catfish 0.97 Catfish 0.88
7 Crabs 0.64 Crabs 0.66 Crabs 0.68
8 Cod 0.57 Cod 0.51 Cod 0.47
9 Clams 0.44 Clams 0.44 Clams 0.45
10 Flatfish 0.37 Scallops 0.31 Flatfish 0.32
Total 15.0

Of the 11 varieties shown in the table, nine are low or very low in mercury (see table). Canned tuna and cod are the exceptions. Cod has a slightly above average methylmercury level; see Mercury in Tuna Fish.

Overall, 67 percent of the fish and shellfish Americans eat have low or very low mercury levels. That’s good news. But some fish—including popular varieties such as canned albacore tuna, swordfish, tuna steaks, tuna sushi, sea bass, and halibut—contain moderately high to very high mercury levels. People who eat these fish often (more than once or twice a week, depending on the fish variety) can easily be exposed to excessive methylmercury doses.

See our listing of fish and shellfish by mercury levels.