The Minnesota Department of Natural Resources (DNR) and the Minnesota Department of Health issued their guidelines for state lakes recently.
The alert affects larger fish found in local lakes such as northern pike, walleye, channel catfish, and carp. The alert warns women of child bearing age and young children that they should only eat one meal a month of catfish, northern pike, and walleye (see chart).
Paul Deadrick, an avid fisherman in the Paynesville area, doesn't feel there is much reason for concern for Lake Koronis game fish. Deadrick said everybody likes to eat fish, but it isn't a meal they would eat on a regular basis. "We probably average eating fish twice a month," he said.
According to the health department, Minnesota's fish are among the cleanest in the Great Lakes Region. Yet chemicals such as mercury, PCBs, and dioxin have been found in some fish from certain waters. The levels of these chemicals are usually low and in Minnesota there are no known cases of illness from these contaminants.
Dave Coahran, Spicer, Department of Natural Resources Fisheries Department, said mercury is found in all lakes. It is a naturally-occurring metal which is present at very low levels in bedrock, soil, and water throughout Minnesota. Mercury evaporates into the air, then returns to earth as a water soluble form in snow and rain.
The Minnesota Pollution Control Agency estimates that 25 percent of the mercury that reaches Minnesota's lakes comes from rocks or volcanic activity. Other sources of airborne mercury include fungicides in latex paints, burning of coal and other fossil fuels, and burning of municipal solid waste.
To ensure good health, the health department has guidelines for how often these fish can be safely eaten.
Guidelines to reduce health risk
Coahran recommends keeping only smaller fish to eat such as blue gills, crappies, and sunfish. Walleye and northern pike are higher on the food chain and contaminants such as mercury and PCBs build up in these large predator fish.
The DNR guidelines suggest making smaller meals out of big fish. Freeze part of your fish to space the meals out over time.
Cleaning and cooking your fish properly is important. Chemicals such as PCBs and dioxins are found in fatty tissues so removing the skin of fish and trimming the fillets to remove the fatty areas can reduce levels of chemicals by 20 to 50 percent. Broiling, baking, or grilling fish so that the fat drips away reduces PCB and dioxin levels even further. Poaching and deep-fat frying removes some contaminants, but the broth or oil need to be discarded.