We have much more mercury in our environment than ever before. Although mercury is a naturally occurring heavy metal it is also highly toxic.

Conservation organisation WWF estimates that around 3,400 tonnes of mercury, two-thirds of the total amount entering the oceans, is emitted each year by human activities.

Mercury And Seafood: 5 Facts

1. Most fish have trace amounts of mercury

2. The bigger the fish, the higher the mercury

3. You can’t see, smell, or taste mercury contamination in fish

4. Cooking has no effect on mercury, and you can’t avoid it by cutting off the skin or other parts of the fish

5. The World Health Organisation (WHO) puts mercury in the TOP 10 CHEMICALS of major public health concern


Eating shark is not just bad for conservation. As the predators at the top of the food chain, sharks can have the most mercury of all species. Campaigners have been taking advantage of this fact to protect sharks against the increasing demand for shark fin soup.

The US Food and Drug Administration says 1 in 3 sharks contains a high mercury concentration that passes safe limits.

Indonesia’s National Agency for Drug and Food Control found that sharks off their waters had levels of mercury harmful to human health.



  • Mercury finds its way to the ocean in a number of ways
  • It is released into the atmosphere as a by-product of fossil fuel burning, smelting or waste incineration

  • It returns to its liquid form and falls into the ocean or it can run off as a pollutant from industries like gold mining process and into waterways.
  • Mercury is then transformed by microbes in the ocean into a form that is digestible to fish (methylmercury)
  • Fish take in tiny amounts of mercury, but that mercury accumulates inside the body of fish – and the bigger the fish, the more mercury


The US Food and Drug Administration (FDA) along with the Environmental Protection Agency (EPA) have been recommending certain vulnerable sectors of society cut back on seafood, namely pregnant and breast-feeding woman and young children


1.Eat ONLY up to  12 ounces a week of a variety of fish and shellfish that are lower in mercury

2.Do not eat shark, swordfish, king mackerel, or tilefish from the Gulf of Mexico because they contain high levels of mercury

3.Cut back on the amount of tuna

4.Check where your fish comes from


  • Affects the nervous system even at low levels
  • May have toxic effects on the digestive and immune systems, and on lungs, kidneys, skin and eyes
  • Harmful to unborn children


Taking predatory fish off your plate will reduce your mercury intake. Here are some to avoid:

  • King mackerel
  • Marlin
  • Orange roughy
  • Shark
  • Swordfish
  • Tilefish
  • Ahi tuna
  • Bigeye tuna

Read the rest of this article in 2016 Issue 3 Volume 142 of Asian Diver magazine by subscribing here or check out all of our publications here.

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