Surveys by the Department of Natural Resources have confirmed zebra mussels in a western stretch of the Minnesota River. Because there is no significant natural or human-made barrier that could prevent downstream spread, the entire Minnesota River, to its confluence with the Mississippi River, will be added to the Infested Waters List. To reduce the risk of spreading aquatic invasive species, activities like bait harvest, commercial fishing, and water use are managed differently in infested waters.
Based on individual captures in 2016 and 2017, the Minnesota River will also be added to the Infested Waters List for bighead carp and grass carp from Granite Falls to the confluence with the Mississippi River. The DNR has already been in contact with some of the businesses, such as commercial anglers and bait harvesters, who would be affected by this designation. Changes in those regulated commercial activities on the Minnesota River will now match Mississippi River regulations. These designations and regulation changes are not unexpected.
“We consider these designations carefully, especially when they affect businesses and people,” said DNR invasive carp coordinator Nick Frohnauer. “The tipping point was the recent capture of a large bighead carp with eggs. Although it’s just a few individuals, both male and female fish have been captured. This designation is a precautionary tool to help minimize risks.” Last September, the DNR confirmed zebra mussels in Lac qui Parle, a Minnesota River reservoir.
Recent DNR surveys confirmed adult zebra mussels behind the Granite Falls Dam and zebra mussel larvae, called veligers (VEL-uh-jers) at four of seven sites on the Minnesota River, from Montevideo to near New Ulm. No veligers were detected at survey sites near St. Peter, Chaska, or Minneapolis and St. Paul.
Zebra mussels, bighead carp and grass carp are not native to Minnesota. Zebra mussels can compete with native species for food and habitat, cut the feet of swimmers, reduce the performance of boat motors, and cause expensive damage to water intake pipes. Invasive carp can compete with native species for food, dramatically reduce aquatic vegetation and diminish water quality.
To protect the state’s waters from the spread of invasive species and the environmental, recreational and economic damage they cause, Minnesota law requires boaters and anglers to: Clean watercraft of aquatic plants and prohibited invasive species. Drain all water by removing drain plugs and keeping them out during transport. Dispose of unwanted bait in the trash. Some invasive species are small and difficult to see at the access.
To remove or kill them, take one or more of the following precautions before moving to another waterbody, especially after leaving infested waters: Spray with high-pressure water. Rinse with very hot water (120 degrees Fahrenheit for at least two minutes or 140 degrees Fahrenheit for at least 10 seconds). Dry for at least five days. More information is available on the aquatic invasive species page.