Most people can safely eat fish 2-3 times per week. This article reviews mercury in tuna and tells you whether it’s safe to eat this fish. And while eating too much of this fish may be bad for your health, it is also bad for dwindling bluefin tuna populations. “Mercury levels in bluefin are likely to be very high regardless of location,” said Tim Fitzgerald, ... an owner of Gourmet Garage, said: “We’ll look for lower-level-mercury fish. Bigeye and yellowfin, also known as ahi, are common in sushi. Scott K. Johnson - Dec 6, 2016 4:24 pm UTC
Pick your (dose of) poison — Mercury levels drop in Atlantic bluefin tuna Study shows 19-percent improvement in just 8 years. Mercury Levels in Commercial Fish and Shellfish from 1990-2012 by Species These include fresh/frozen tuna, shark, swordfish, marlin, orange roughy and escolar (Note: Additional health information on escolar is available from Health Canada's Fact Sheet on escolar and CFIA's fact sheet . In 4.3% of swordfish and in 44.3% of bluefin tuna analyzed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 microg g(-1) wet wt). This mercury can also concentrate up the food chain.

“Fish to Avoid” column. Both types, along with bluefin, are high in mercury and should be eaten infrequently, if at all. Money talks, and politicians can be persuaded. Government agencies have warned consumers to avoid eating foods with high mercury levels. Mercury, when consumed as part of a normal, healthy diet is not usually a problem for most healthy adults and children. The answer -- measure the mercury level from up higher on the loins of the fish. This, coupled with their exorbitant value in the sushi market, has led to severely depleted populations. Mercury occurs naturally in the environment, can be released into the air through industrial pollution and accumulates in streams and oceans where it is turned into methylmercury. Some species may have high levels of mercury content. These fish come from sources that are overfished, caught or farmed in ways that harm other marine life or the environment. Found singly or in schools patrolling reef slopes over coastal and oceanic reefs. Fish take up mercury from streams and oceans as they feed.
Fish absorb the methylmercury as they feed in these waters, it accumulates, and then we consume it when we eat the fish. Most people are exposed to mercury via food.

Avoid these products, at least for now. Nearly all fish and shellfish contain levels of methylmercury. Food processing, preparation and cooking techniques don’t significantly reduce the amount of mercury in fish. Also known as the Blue Jack Fish. One of the big reasons that we are having this excellent extended season on big Bluefin tuna … Bluefin tuna, on the other hand, grow slower and take longer to reproduce. Tuna is a popular and nutritious saltwater fish, but you may worry about its mercury content.

Therefore, predatory fish that eat lots of other fish for food tend to contain higher levels of mercury.