August 2005





It is well documented that less than 1 percent of Minnesota's native prairies remain intact. What is the significance of those that remain and of prairie landscapes as a whole?

Nearly half of all of Minnesota's rare and endangered species live on prairies, which make preserving these complex ecosystems critical to protecting the state's natural heritage. Prairies also supply habitat for a wide variety of wildlife species, reduce soil erosion, and provide important pastureland for cattle and other livestock. The challenge is keeping these few remaining prairie remnants healthy and vibrant. In their natural state, prairies were maintained by climate, fire and grazing by bison. This allowed native plants to regenerate annually by removing dead grasses and keeping the landscape free from becoming shrubby and overgrown with tree species such as red cedar, box elder, elm, oak and aspen. Today, controlled burns, haying and grazing can mimic these natural processes. Of course, too much disturbance can also be a problem. Season-long overgrazing, for example, can slowly convert a native prairie pasture to one dominated by exotic cool season grasses such as Kentucky bluegrass, and noxious weeds such as Canada thistle and leafy spurge. Although it is not possible to recover all 18 million acres of prairies that covered Minnesota prior to European settlement, preserving what is left will protect a small piece of the state's history.

Peter Buesseler, DNR Scientific & Natural Area Prairie Biologist


DNR fisheries biologists recently discovered zebra mussels in Mille Lacs Lake while doing lake bottom surveys. What type of impacts are these invasive species likely to have on Minnesota's lakes and rivers, and how can we prevent their spread?

Zebra mussels feed by filtering out small particles in the water, and, when they are abundant, zebra mussels can easily reduce key food sources for larval fish and other aquatic life. In some lakes, where this invasive species has been present in extremely high numbers for many years, such as Lake Erie, they changed the entire lake ecosystem and impacted fish populations. Filtering the water also increases water clarity, which in turn can increase the depth that aquatic plants may grow and may increase the potential for nuisance blue-green algae. These fingernail-sized invaders have been known to severely reduce or eliminate native mussel species, as well as clog water systems of power plants, water treatment facilities and irrigation systems. Female zebra mussels can produce as many as 1 million eggs per year, which makes it especially important that boaters, anglers and waterfowl hunters help prevent their spread by removing zebra mussels and aquatic plants from their watercraft and draining all lake water from boats and equipment before leaving the water access. If boats have been moored, people should wash them with hot water or dry them for five days before going to another body of water. Additional information is available at the DNR's Web Site.

Jay Rendall, DNR Invasive Species Program coordinator


What should anglers do if they are fishing on a catch-and-release only body of water, and they catch what they think may be a record-setting fish?

Catching a big fish regardless of the species is always a thrill for any angler. Only fish that are caught and can be kept legally are eligible for state record verification. In addition, all fish must be positively identified by the DNR before a state record is awarded. Some taxidermists will build a replica from the measurements and photo you might take before releasing the fish. There is another way for anglers to enjoy the rewards of catch and release. The Master Angler program, which is sponsored by the DNR and Minnesota Fishing Hall of Fame, aims to recognize responsible anglers who release quality fish. The program, which is open to all licensed anglers in Minnesota, includes categories for both adults and youth. Details about this program are available at Additional information on state record fish and proper catch and release techniques can be found in the 2005 Fishing Regulations.

Jenifer Matthees, DNR aquatic education coordinator


DNR foresters have uncovered an outbreak of jack pine budworm in a number of northern Minnesota counties. What is jack pine budworm and how does it impact these trees?

Travelers to northern Minnesota counties of Beltrami, Becker, Hubbard, Wadena, Cass and Crow Wing are noticing the impacts of jack pine budworms. These tiny green caterpillars feed on pollen cones and young jack pine foliage during the spring, which causes needles to turn from green to a reddish-orange color and fall off. In addition to jack pines, there has been an unprecedented budworm outbreak on red pine trees in the same counties. These outbreaks occur naturally on six-year cycles, and in any given location, they typically spend two years causing defoliation before disappearing for another six or more years. Budworms can cause top-kill and cause tree mortality when the trees are old or under stress from drought, over-crowding or root system damage. Bio-rational pesticide treatments can help protect individual trees or trees on small tracks of land when caterpillars begin feeding in the springtime. Larger tracts of forest are best managed by rotation age, thinning and, if need be, by salvage. September is the best time to determine the amount of damage done to trees when all of the reddish-orange needles have fallen to the ground.

Jana Albers, DNR forest health specialist


Every year the DNR and Minnesota Department of Health issue a fish consumption advisory that warns consumers of potential health issues. What happens if people eat too much fish?

Fish are a great source of protein, vitamins and minerals, and are low in saturated fat. However, any fish may contain harmful contaminants such as mercury or PCBs. Since it is not possible to see, smell or taste any of these contaminants the amount of fish consumed should be kept to a minimum to safeguard against potential health risks. For example, even a small amount of mercury can damage a brain that is just starting to form or grow. This is why young children, unborn and breast-fed babies are at most risk. Too much mercury may affect a child's behavior and lead to learning problems later in life. Mercury can also harm older children and adults, but it takes larger amounts before the effects are noticeable. Prolonged exposure may damage kidneys and the nervous system. It may also cause tingling, prickling or numbness in hands and feet or changes in vision. Exposure to PCBs during pregnancy may lower birth weight, reduced head size and delayed physical development; PCBs may also cause cancer. Additional information is available on the Department of Health Web site.

Patricia McCann, Minnesota Department of Health