Fish Tale

Updated November 8, 2006

Although oceanic ecosystems have a great ability to rebound, the ocean's fisheries are in such a state of decline that by 2048 all species of wild seafood could collapse, their numbers declining to a tenth of their historic highs. So concludes a comprehensive study of the human impact on marine biodiversity published in the November 3, 2006 Science.

Overfishing, while it plays a large role, is not the only factor associated with the decline, note the study authors. Loss of nursery habitats (such as wetlands, oyster reefs and seagrass beds) and the decline in filtering and detoxification provided by submerged vegetation, wetlands and animals such as krill, clams and sponges, have also significantly damaged water quality and put a strain on species. On the bright side, the study found data from 44 marine reserves and 4 large-scale fishery closures showing an average 23 percent increase in the number of species, with substantial benefits to fisheries on the edges of reserves.

To help you choose non-contaminated seafood from healthy fisheries, The Green Guide offers its "Fish Picks" list, distinguishing those with low mercury, in our "Yes" column, from the those that are ovefished, have high bycatch rates or contain high mercury, in our "No" column.

Health

Fish give us heart-healthy omega-3 fatty acids and make a perfect protein-filled, lean meal whether grilled, baked, poached or served as sushi. Mercury, however, remains a real concern. As reported in The New York Times, Michael O. Leavitt, the head of the Environmental Protection Agency (EPA), warns that all U.S. freshwater fish are contaminated with mercury. And the EPA has reported that 16 percent of American women currently have enough of the brain-damaging heavy metal in their bloodstreams to increase the risk of harming a fetus. Fair Warning, a 2005 21 state survey of fish bought in supermarkets confirmed that swordfish and tuna steaks still contain mercury levels unsafe for pregnant women and children. Because mercury harms developing brains and nervous systems, nursing and pregnant mothers should refrain from eating the most contaminated fish (listed as MM on our Fish Picks Card) nor should any be fed to small children.

Furthermore, a 2006 Consumer's Reports (CR) study on canned light tuna found that fish in 6 percent of the cans tested contained high levels of mercury. In a split with FDA guidelines, they recommend that pregnant women avoid canned light tuna entirely. CR states, however, that young children can safely eat between half and a whole six ounce can of canned light tuna per week. To be cautious, eat only one portion (up to 4.5 ounces) of fish per month from the Sometimes list of The Green Guide's Fish Picks.

According to a Harvard study, published online in Environmental Health Perspectives, pregnant women who ate more than two servings of low-mercury fish had children with IQ scores an average of 4 points higher with each extra serving of fish per week. However, mothers who ate high mercury fish gave birth to children whose IQ scores average 7.5 points lower with each extra serving of fish.

Polychlorinated biphenyls (PCBs), which can interfere with the body's hormonal systems and harm the brain, have been shown to accumulate in farmed salmon at levels up to seven times higher than they appear in the wild, according to a study published in Science this January. You can avoid them by choosing wild Alaskan or Californian salmon, and at the same time you'll be supporting these well-managed fisheries. Since many lake and river fish have been found to contain unsafe levels of PCBs, before fishing or eating freshwater fish, check for EPA advisories in your area (see Resources below for websites).

Environment

Seventy-five percent of the world's fish species are either being caught at maximum levels or in a state of collapse from overfishing, according to the United Nation's Food and Agriculture Organization. In 2003, Nature reported that large predator fish have suffered the most from industrial fishing, with tuna, swordfish, cod and halibut reduced 90 percent worldwide. Your choices can take the pressure off overfished species and help reduce damage to habitats caused by practices such as bottom trawling, which destroys deep sea coral beds. Beyond that, by choosing species that are harvested responsibly, you help prevent the catching of unwanted fish and animals that are disposed of (referred to as "bycatch")—these include endangered sea turtles caught and killed in shrimp nets. Fish farms pose a threat, as escaped non-native fish overtake local fish in an area, a worry which has kept Alaska from allowing salmon to be farmed in the state. However, with proper management, some species such as abalone and catfish can be farmed successfully without harming the environment.

Resources

Environmental Protection Agency:
Mercury and fish, www.epa.gov/ost/fish
Listing of Fish and Wildlife advisories, map1.epa.gov

Food and Drug Administration:
Mercury Levels in Commercial Fish and Shellfish: vm.cfsan.fda.gov/~frf/sea-mehg.html
Mercury in Fish, FDA Monitoring Program (1990-2003):
vm.cfsan.fda.gov/~frf/sea-mehg.html

Environmental Working Group:
Mercury in Seafood page, www.ewg.org/issues/mercury/index.php
PCBs in Farmed Salmon Report, www.ewg.org/reports/farmedPCBs/

Monterey Bay Aquarium:
Seafood Watch Card www.mbayaq.org/cr/cr_seafoodwatch/sfw_regional.asp