- Sophia Kamveris, MS, RD
Sorry Charlie, Not All Tuna is Good for You
Tuna fish has been in the news lately due to its mercury content. The Mercury Policy Project (MPP) of Montpelier, Vermont (a non-profit working to reduce mercury in the environment), is pushing the U.S. Department of Agriculture to discontinue serving tuna in school lunch programs after a test of 59 (industrial-sized) canned tuna sold to schools in 11 states revealed highly variable levels of mercury -- some of which exceeded federal guidelines. The average methylmercury content ranged from 0.02 to 0.64 parts per million in light tuna and between 0.19 and 1.27 parts per million in albacore tuna. (The Environmental Protection Agency's maximum acceptable dose for methylmercury, a potent neurotoxin, is one-tenth of a microgram per kilogram of a person's body weight.)
Based on their findings, the project’s report recommends that all children not eat (white) albacore tuna, and that young children limit eating canned light tuna to only once a month, while older children eat it only twice a month. They also suggest school lunch programs limit canned tuna servings to twice a month and eventually phase it out, moving toward serving lower-mercury seafoods, such as salmon and shrimp.
This latest recommendation now joins the EPA and FDA warnings that women who are pregnant, or might be pregnant, eat only up to two meals, or 12 ounces, of fish and shellfish a week. Again, due to potential mercury concerns for the fetus.
Albacore tuna is a highly migratory fish found in many oceans around the world but it is more plentiful in the Pacific Ocean and less so in the North Atlantic. In the U.S., albacore is also referred to as white tuna, and when prepared as sushi, it is known as “shiro maguro.”
Fish become contaminated with mercury from industrial pollution in waterways. Bacteria in the waters transform (dumped) mercury into methylmercury, a more biologically active and dangerous form of the element, according to the Food and Drug Administration. Fish eat the bacteria and the mercury accumulates in the largest and oldest fish, which is why long- lived and large species such as tuna have higher levels. Canned light tuna comes from the skipjack species of tuna, which are smaller and often younger. They haven't been around long enough to accumulate as much methylmercury in their systems. Albacore is harvested older and therefore contains more mercury than light tuna.
Albacore is caught with a variety of gear, including troll, pole-and-line and longline. There is little or no bycatch (defined as those fish caught unintentionally in a fishery while catching other fish) when albacore is caught with troll or pole gear. However, longlines, the most common method, results in large quantities of bycatch, including threatened or endangered species such as sea turtles, sharks and seabirds. Since there are no international laws to reduce bycatch, these longline fleets are contributing heavily to the long-term decline of some of these species.
Wild Planet and Safe Catch are two of the companies known for its “sustainability” practices. Sustainable seafood is either fished or farm-raised; these methods help to maintain (or increase) production in the future without affecting the ecosystems it came from. Wild Planet fish is caught, one-by- one, off the Pacific Northwest in the United States using hand lines and "pole and troll" methods. They contend that this type of fishing ensures that other marine life, such as dolphins and turtles, are not harmed. They hand-cut and pack their tuna steaks in their own, natural juices-they suggest you don’t drain the cans, which is rich in natural fish oils. That’s how they retain a higher omega 3-fatty acid content as compared to other brands. That, and the fact that they cook their albacore only once, while the larger, national brands of tuna lose most of the Omega 3’s in their pre-cooking process. These brands also pack their fish in water or vegetable oil.
By nature, troll-caught albacore in the North Pacific fishery are lower in mercury because these migratory fish are smaller (about 9 to 25 pounds) and younger (three to five years old) than the long-line caught, older fish that reach up to 70 pounds after ten years of growth. The longer a fish lives and feeds, the more it bio-accumulates mercury. While all fish caught along the West Coast are low in mercury compared to larger overseas fish, Wild Planet packs only these smaller fish.
According to the Monterey Bay Aquarium Seafood Watch at http://www.montereybayaquarium.org, whenever possible, look for troll-or pole-caught albacore. United States and Canadian North Pacific are a "BEST CHOICE," while longline-caught albacore is ranked as "AVOID," except longline-caught from Hawaii, where strict bycatch regulations and healthy populations result in a "Good Alternative" ranking.
Fatty fish is higher in Omega-3 fatty acids that not only play a significant role in heart health, but also in cognitive and inflammatory disease states. The American Heart Association recommends eating fish at least two times a week. To learn more about the recommendations to help you choose a safer and more sustainably raised fish, check out: http://www.seafoodwatch.org.