State issues advisory for northern pike, walleye The state is recommending anglers limit their consumption of large northern pike and walleye from the Twin Lakes area in Kingsbury County due to mercury levels exceeding 1 part per million (ppm). Recent testing of game fish in the lakes found mercury levels exceeded the 1 ppm limit in northern pike 19 inches and longer and in walleye 18 inches and longer. Larger, older fish have more exposure to mercury contamination and thus accumulate more mercury in their flesh.
The consumption advisory is for West Highway 81/Twin Lakes, a complex that includes all contiguous waters west of Highway 81 in Kingsbury County.
The Department of Health recommends that healthy adults eat no more than 7 ounces per week of the specified northern pike and walleye. Children younger than 7 should eat no more than one 4-ounce meal of the fish per month. Women who plan to become pregnant, are pregnant or are breast-feeding should have no more than one 7-ounce meal of the fish per month. Seven ounces of fish is roughly the size of two decks of playing cards.
When mercury levels in fish reach 1 ppm, meals should be spaced to prevent potentially dangerous mercury accumulation. The Food and Drug Administration (FDA) has set 1 ppm as the action level for commercial fish. This action level is 10 times lower than the lowest levels associated with negative neurological effects observed in mercury poisoning incidents. The Department of Health uses the FDA action level to issue consumption information to the public.
Fish in South Dakota lakes and rivers are tested for metals, pesticides, and PCBs as a collaborative effort of the South Dakota Departments of Health, Game, Fish & Parks, and Environment & Natural Resources.
State consumption advisories are also in effect for fish from Bitter Lake near Waubay in Day County and Lake Isabel on the Cheyenne River Sioux Reservation in Dewey County. The Cheyenne River Sioux Tribe also has a consumption advisory in place for Lake Isabel. For more information about mercury and fish consumption, see the department's web site at www.state.sd.us /doh/Fish.