An Outdoor View: A little mercury with your fish?

Posted: Friday, December 03, 2010

ANACORTES, WASHINGTON -- While visiting relatives in the Evergreen State, I got to wondering whether it's safe to eat the fish caught here. The answer is yes and no.

Some species, such as yelloweye rockfish, live long lives, so they accumulate more mercury than short-lived species. Due to the risk of high mercury concentrations in fish in Puget Sound, the Washington State Department of Health (DOH) recommends no consumption of yelloweye rockfish, period.

The DOH recommendation for all other species of rockfish taken from urban areas of Puget Sound is no more than one meal per week. For chinook salmon taken from Puget Sound, the DOH recommends just one eight-ounce serving per week. If the fish is a blackmouth, a small chinook that never leaves Puget Sound, it's likely to contain high levels of polychlorinated biphenyls (PCBs), another toxin. You're advised to eat only two eight-ounce servings of blackmouth per month.

What's the big concern about mercury in fish?

In children, mercury can affect the development of the nervous system, which can cause learning disabilities. In adults, the heart, immune system and reproductive systems can be affected. In a study of 20 Washington lakes, 10 lakes contained mercury in levels "of concern." According to the DOH, "Mercury occurs naturally and can be released from rocks and volcanoes and deposited globally by winds and rain. When deposited in water, it changes to an organic form that can bio-accumulate in fish and humans."

In Washington, if you're a young child or a pregnant woman, you run the risk of ingesting mercury if you eat largemouth or smallmouth bass more than twice a month. If you're a nursing mother, or if you could become pregnant, eating too much of these bass poses a risk to your baby or unborn fetus. And you should never eat northern pike/minnow at all.

There's no getting away from mercury. Even fish caught in Alaska's so-called pristine waters contain it. The Alaska Department of Health and Social Services has published a "Guide to Eating Fish Safely for Alaska Women and Children" that pertains to women who are or can become pregnant, nursing mothers and children 12 and under. "Everyone else can eat as much seafood as they like," says the guide.

Women and children should mix and match fish meals so as to accumulate up to 12 points per week, according to the guide. A meal size is 6 ounces (uncooked weight) for adults and 3 ounces for children 12 and under. The following fish from Alaska waters received zero points: all species of salmon, halibut under 20 pounds, lingcod under 30 inches, Pacific cod, black rockfish, walleye pollock and Pacific ocean perch. Canned, chunk, light tuna from other waters also received zero points.

On the other end of the scale, fish from Alaska waters receiving 12 points were halibut of 90 pounds or more, lingcod of 45 inches or more, salmon shark and spiny dogfish. The guide gave yelloweye rockfish from Alaska waters 6 points.

I didn't try to determine whether fish caught in Alaska waters contained more or less mercury than fish caught in Washington. I think what's important is that people realize that all fish contain mercury, and that the larger, longer-lived ones contain more of it.

For more information:

Les Palmer lives in Sterling.

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