List of fish high in mercuryPawel Malczewski
The mercury content of some fish is dangerously high. Large predatory fish such as shark, swordfish, marlin, or king mackerel contain more methylmercury in a small serving than a weekly maximum safe limit for most people (limit is dependent on the body weight). For a quick answer click here.
There is no doubt that seafood and fish contribute many excellent health benefits and is considered one of the healthiest food groups.
In addition to a wide range of health benefits, their flesh also concentrated methylmercury. The concentration levels of this toxic chemical depend on various factors such as the species, size and age of the specific fish or seafood. It also varies depending on the pollution levels of the waters from which the fish is extracted.
The health benefits of fish and seafood outweigh the risk of mercury exposure if: (1)United States Environmental Protection Agency. How People are Exposed to Mercury. Available here.
- The fish and seafood consumed has low levels of mercury
- It is consumed within the weekly recommended limits
In the U.S. population, the total fish and seafood consumption is (2)Sunderland EM. Mercury Exposure from Domestic and Imported Estuarine and Marine Fish in the U.S. Seafood Market Environ Health Perspect. 2007 Feb; 115(2): 235–242. Available here.:
- 39% – 43% of mercury comes from tuna (read more..)
- Swordfish (8%)
- Pollock (8%)
- Shrimp (5%)
- Cod (4.5%)
Mercury recommended daily intake
The current safe daily limit for mercury intake has been established to be 0.1 micrograms per kg of body weight. The following table shows some examples of safe weekly limit of mercury per body weight:
|Body Weight (kg)||Limit of mercury (mcg/week)|
The general recommendations for the maximum safe limit intake of mercury vary slightly from country to country since fish may be caught in different waters with different pollution levels.
How much fish should you eat per week?
In summary, the recommendations for an adult are 2-3 serves (1 serve = 150g) of fish per week. If you wish to eat more than that, you should make sure that you include low mercury level species. (3)U.S. Department of Health and Human Services. Dietary Guidelines for Americans. Available here.
For a special group: pregnant, planning to be pregnant or breastfeeding women (1 serve = 150g) and small children (1 serve = 85g) the recommendations are:
- 2-3 serves per week of low mercury small fish or
- 1 serve per week of catfish, orange roughy (deep sea perch).
- Avoid fish and seafood high in mercury such as tilefish, shark, swordfish, marlin, and king mackerel. (4)United States Environmental Protection Agency. How People are Exposed to Mercury. Available here. (5)United States Environmental Protection Agency. What You Need to Know about Mercury in Fish and Shellfish. Available here.
Australian authorities allow some intake of these fish (1 serve per fortnight). However, considering the potential dangers, many health professionals advise to avoid them altogether. (6)NSW Food Authority. Australia. Fish and mercury. Available here.
NOTE: Due to varied levels of mercury in fish and seafood and recent evidence of the health risks associated with low levels of mercury intake the current official recommendations may be undervalued. In addition to following these recommendations, it is important to keep track of the fish consumption using the more detailed list of mercury contents. (7)Lunder S, Sharp RC. US Seafood Advice Flawed on Mercury, Omega-3s. 2014 Jan. Available here.
Mercury levels in fish
The following table shows the concentration of mercury in different species of fish and seafood in studies conducted between 1990 and 2010: (8)FDA – U.S. Food and Drug Administration. Mercury Levels in Commercial Fish and Shellfish (1990-2010). Available here.
|Species||MEAN (PPM)||MAX (PPM)||mcg in 3 oz serving|
|TILEFISH (Gulf of Mexico)||1.45||3.73||123.25|
|TUNA (FRESH/FROZEN, BIGEYE)||0.689||1.816||58.565|
|MACKEREL SPANISH (Gulf of Mexico)||0.454||1.56||38.59|
|GROUPER (ALL SPECIES)||0.448||1.205||38.08|
|TUNA (FRESH/FROZEN, Species Unknown)||0.415||1.3||35.275|
|TUNA (FRESH/FROZEN, ALL)||0.391||1.816||33.235|
|TUNA (FRESH/FROZEN, ALBACORE)||0.358||0.82||30.43|
|TUNA (FRESH/FROZEN, YELLOWFIN)||0.354||1.478||30.09|
|TUNA (CANNED, ALBACORE)||0.35||0.853||29.75|
|CROAKER WHITE (Pacific)||0.287||0.41||24.395|
|WEAKFISH (SEA TROUT)||0.235||0.744||19.975|
|MACKEREL SPANISH (S. Atlantic)||0.182||0.73||15.47|
|LOBSTER (Species Unknown)||0.166||0.451||14.11|
|BASS (SALTWATER, BLACK, STRIPED) ||0.152||0.96||12.92|
|TUNA (FRESH/FROZEN, SKIPJACK)||0.144||0.26||12.24|
|TUNA (CANNED, LIGHT)||0.128||0.889||10.88|
|PERCH OCEAN *||0.121||0.578||10.285|
|LOBSTER (NORTHERN / AMERICAN)||0.107||0.23||9.095|
|MACKEREL CHUB (Pacific)||0.088||0.19||7.48|
|CROAKER ATLANTIC (Atlantic)||0.065||0.193||5.525|
|MACKEREL ATLANTIC (N.Atlantic)||0.05||0.16||4.25|
|SALMON (FRESH/FROZEN) *||0.022||0.19||1.87|
|SALMON (CANNED) *||0.008||0.086||0.68|
Like with any other foods, fish and seafood is only healthy if it forms a part of a balanced diet. The risk of over-consumption of any particular fish or seafood has the potential of accumulating specific toxins and also leads to an imbalance of nutrients.
My advice is:
- Eat fish and seafood with a low level of mercury and high level of omega-3 fatty acids such as sardines, mackerel, herrings, Atlantic salmon, canned salmon and “light tuna”.
- Avoid fish with a very high mercury concentration such as shark (flake), marlin, swordfish, king mackerel and tile-fish. Although it is most likely that the fish you eat contains mercury levels as shown in the “average amount” column, you can never be sure. Some fish have shown to have much higher levels of mercury shown in the “maximum amount” column. (9)United States Environmental Protection Agency. What You Need to Know about Mercury in Fish and Shellfish. Available here.
- Use the above table of mercury levels in various fish and seafood to make your choices and to keep track of what you eat.
References [ + ]
|1.||↑||United States Environmental Protection Agency. How People are Exposed to Mercury. Available here.|
|2.||↑||Sunderland EM. Mercury Exposure from Domestic and Imported Estuarine and Marine Fish in the U.S. Seafood Market Environ Health Perspect. 2007 Feb; 115(2): 235–242. Available here.|
|3.||↑||U.S. Department of Health and Human Services. Dietary Guidelines for Americans. Available here.|
|4.||↑||United States Environmental Protection Agency. How People are Exposed to Mercury. Available here.|
|5.||↑||United States Environmental Protection Agency. What You Need to Know about Mercury in Fish and Shellfish. Available here.|
|6.||↑||NSW Food Authority. Australia. Fish and mercury. Available here.|
|7.||↑||Lunder S, Sharp RC. US Seafood Advice Flawed on Mercury, Omega-3s. 2014 Jan. Available here.|
|8.||↑||FDA – U.S. Food and Drug Administration. Mercury Levels in Commercial Fish and Shellfish (1990-2010). Available here.|
|9.||↑||United States Environmental Protection Agency. What You Need to Know about Mercury in Fish and Shellfish. Available here.|