How to help stop the spread of invasive species in Minnesota

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With temperatures rising, Minnesotans are once again invading our lakes, rivers and forests--but along with them other harmful invaders wait there too. It’s this time of year we’re reminded of the plants, fish and insects that are not native to our state but are still here, and spreading. 

The DNR and other biologists have had to set realistic goals when it comes to invasive species in our lakes, rivers and forests. They say it’s not so much about winning the war as it is about containing the enemy. 

“People do really well in Minnesota following our laws,” said Heidi Wolf, the DNR Invasive Species Unit supervisor. “There’s a high knowledge rate and a low violation rate, so the biggest thing is to clean your boats.”

In Minnesota, cleaning boats starts at the landings. The signs to remind people about aquatic invasive species and how to stop their spread are everywhere. This year, 1,000 boat landings will be staffed with people there to help. Boat hitchhikers, like Eurasian milfoil, starry stonewort and zebra mussels get snuffed out at those checkpoints.

“Make sure you are cleaning all your aquatic recreation equipment,” said Wolf. “You’re draining everything. You’re making sure you dispose of all your bait. Those are the laws you have to follow. We also recommend you wash and dry your items, so that you’re making sure you’re not transporting anything. And any dock or lift has to be out of the water for 21 days before it’s put into another water body.”

It’s not just our 10,000 lakes that are seeing invasive species. Minnesota is blessed with some of the most beautiful and abundant rivers of anywhere in the country, but the scenic St. Croix River is one of three where invasive carp have also been found.

“We don’t think of ourselves as being infested with invasive carp, but we have had sightings of both bighead and silver carp in the Minnesota, the Mississippi and St. Croix Rivers, so we’re definitely concerned,” said Wolf.

The introduction of a new fish to the river system could be a shock to the native wildlife.

“It would change a lot,” said Wolf. “They would out-compete our native fish significantly. It would change a lot about our ecosystem. If you’ve seen the silver carp they jump in the air when startled, so it would change recreation for us here in Minnesota.”

Already this spring, two bighead carp were caught in nets by the DNR on the St. Croix. The two fish weighed 39 pounds and 46 pounds, respectively. Biologists are tracking a tagged one as part of an invasive carp pilot project that studies their range. If you hook into something odd, report it at

“You are required to do that,” said Wolf. “We would like some photos or you can bring it in to your closest DNR office and if you suspect you’ve seen something, contact us. We definitely want to know.”

Back on dry land, campfires are always a big part of summer life. How and where you get your firewood can be the key to limiting the spread of an invasive bug. Emerald ash borer, the wood boring beetle whose larvae attack and kill ash trees, descended on Minnesota a few years ago, bringing with it the destruction of thousands of ash trees either killed by the beetle or taken down in an effort to stop the spread. 

“Another big thing is to not move firewood because emerald ash borer is a larvae,” said Wolf. “It’s under the bark of the tree you wouldn't know it was infested and if you move that firewood you can spread it further. So we’re telling people to use certified firewood that’s been treated or local firewood.”

So whether it’s the lakes, rivers, or the forests that surround them, biologists say the key to slowing or stopping the spread of invasive species rests with all of us.

“We are lucky in that our rate of spread has been low--again, because people here are pretty knowledgeable and they’re following the rules,” said Wolf. “We have great partners between the University of Minnesota’s aquatic invasive species research center, the counties, lake associations--there’s a lot of people working on the issue making sure the knowledge is widespread and people are doing the right thing.”