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Lake Isabel fish consumption advisory to include largemouth bass

FOR RELEASE: November 14, 2002
Dave Micklos, Health, 773-3364
Dennis Unkenholz, Game, Fish and Parks, 773-4508
Patrick Snyder, Environment and Natural Resources, 773-4729

Lake Isabel fish consumption advisory to include largemouth bass

     (PIERRE) - The state has added largemouth bass 17 inches and longer to its fish consumption advisory for Lake Isabel after finding mercury levels of up to 1.12 parts per million (ppm) in a composite sample of largemouth bass. Lake Isabel is located in Dewey County on the Cheyenne River Sioux Reservation north of the town of Isabel.

     The original Lake Isabel advisory was issued July 16 when testing found mercury levels of 1.19 parts per million (ppm) in a composite sample of northern pike 25 inches and longer. Larger, older game fish typically consume organisms higher on the food chain with progressively more concentrated mercury, thus they accumulate more mercury in their flesh.

     The Department of Health recommends that healthy adults eat no more than 7 ounces per week of either largemouth bass 17 inches and longer or northern pike 25 inches and longer from Lake Isabel. Children younger than 7 should eat no more than one 4-ounce meal of Lake Isabel bass or northern pike per month. Women who plan to become pregnant, are pregnant or are breast-feeding should have no more than one 7-ounce meal of these 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. There have been no incidents of mercury poisoning related to fish consumption reported to the department in South Dakota.

     Fish in South Dakota lakes and rivers are tested for metals, pesticides, and PCB's as a collaborative effort of the South Dakota Departments of Health, Game, Fish & Parks, and Environment & Natural Resources. Since 1994, the state has tested fish from more than 70 locations on more than 60 South Dakota waterbodies. To date, advisories have only been issued for fish from Lake Isabel in Dewey County and from Bitter Lake in Day County. For more information about mercury and fish consumption, see the department's web site at www.state.sd.us/doh/Fish.