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Seafood: green buying guide 10/10

Are you wondering how much seafood you can safely eat? Eating fish has both benefits and risks. Some fish are a good source of heart-healthy omega-3 fatty acids and protein, and are low in saturated fat. In fact, the American Heart Association now urges everyone to eat at least two small portions of fish each week.

But some fish also contain excessive amounts of certain pollutants, including a toxic form of mercury called methylmercury, a toxin that affects the brain and nervous system, and PCBs and dioxins, which are possible carcinogens. Fetuses and young children seem to face the greatest risk from mercury in fish, because of their small size and the vulnerability of the developing nervous system.

Green recommendations

Pregnant women: Follow the FDA recommendation and don't eat tilefish, shark, swordfish, or king mackerel, which are very high in mercury. We further suggest that pregnant women limit their seafood choices to the low-mercury species listed below for two reasons. Tuna can contain high levels of mercury. It is prudent for pregnant women to avoid canned tuna entirely, given the uncertainties about the safety of even chunk light tuna.

Some fish species--including Chilean bass, halibut, American lobster, and Spanish mackerel--occasionally contain as much mercury as the most contaminated types, such as swordfish. And some fish have not been thoroughly tested for mercury.

Women of childbearing age and all children: Avoid the same four high-mercury fish that are off-limits to pregnant women. Women of childbearing age who are not pregnant should eat no more than about three chunk-light cans per week, or one can of solid-light or white tuna. However, women planning to become pregnant should know that mercury can linger in the body after you stop eating the fish.

Young children (up to about 45 pounds) can safely eat about one-half to one 6-ounce can of chunk light tuna per week, or up to one-third of a can of solid light or white. Those weighing from 45 pounds to 130 pounds should eat no more than one to three cans of chunk-light tuna per week, or one-third to one can of solid-light or white tuna.

As for other fish, apart from those on our low-mercury list below, the amount of the metal they contain varies greatly. Some fish can be safely consumed only once a month, while others can be eaten many times. People who want to be as safe as possible can minimize their consumption of these fish.

Women beyond childbearing age and men: More frequent fish intake, including a very occasional serving of a high-mercury species, is unlikely to cause harm. But studies have not determined the acceptable amounts. To be on the safe side, men, older women, and women of childbearing age who are not pregnant, should eat no more than about three chunk-light cans per week, or one can of solid-light or white tuna.

How to choose

Fish that are low in mercury and other contaminants:
Wild caught salmon, shrimp, clams, and tilapia--have consistently low mercury levels. Everyone, including pregnant women and young children, can safely eat them every day. Choosing wild salmon as opposed to farm-raised salmon minimizes exposure to a number of other pollutants.

Other low-mercury species:
Oysters, hake, sardines, crawfish, pollock, herring, flounder, sole, mullet, Atlantic mackerel, scallops, crab, and Atlantic croaker, can be consumed anywhere from once a week to daily, depending on body weight and the fish species.


*Check advisories. State agencies and the EPA periodically issue advisories for locally caught fish based on regional contaminant levels. To find advisories for your region, visit the EPA's fish advisory map, searchable by state.

*Buy the freshest looking fish. If the fish still has a head, it should have clear eyes and bright red gills. If it’s already filleted or cut into steaks, make sure its flesh looks firm, without any blemishes. Avoid any fish that look dried out or slimy. Also, make sure that fish are on ice and separated from each other and that employees are wearing disposable gloves.

*Don’t patronize a fish counter that has an overpowering “fishy” odor. Try asking the clerk to let you sniff your selection, taking care, of course, not to get too close. If the fish smells unpleasant, don’t buy it.

*Refrigerate fresh fish as soon as possible. Fish is among the most perishable of foods. If you won't be eating it within a day, wrap it tightly and put it in the freezer. Properly wrapped fish kept at temperatures below zero should last for about three to six months. Thaw frozen fish in the refrigerator.

*Be sure to keep your hands clean before and after preparing seafood. Scrub the counter space, cutting board and any utensils you might’ve used in preparation too.

*Cook fish thoroughly. To avoid food-borne illnesses associated with fish, make sure you cook it until its flesh is opaque, and flakes easily with a fork.

Related links

For more information on contaminant levels in fish, and to avoid buying species that are in trouble, consult the seafood guide from the Environmental Defense Fund, called “Seafood Selector” or the “Seafood Watch” guide from the Monterey Bay Aquarium.

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