“There’s like the little buoys they put out near the swim beach to keep, boat traffic from coming too close. We used to always like to cling on to those buoys. (My son) went and clung onto one of them, and he got shredded, one of his legs on those little zebra mussels that get on there,” Scott said.

A zebra mussel is a small mollusk with a striped shell that ranges from 1/4 inch to one-and-a-half inches long and attaches itself to hard surfaces underwater. A native mussel is typically bigger, teardrop-shaped and can attach to soft and hard surfaces.

While Scott’s home on Long Lake has yet to be inhabited by zebra mussels, Turtle River Lake in Beltrami County developed evidence of mussels in November.

Since the 1990s, the presence of zebra mussels in Minnesota’s lakes has more than tripled. This has created a billion-dollar problem not only in Minnesota but also nationally and globally.

While the aquatic species spread slowly, its presence in Minnesota’s lakes rose in the late 1990s.

Zebra mussels – native to Eastern Europe and western Russia – were first confirmed in the Duluth/Superior Harbor in 1989, according to the Minnesota Department of Natural Resources (DNR). Scientists believe the invasive species crept into the Great Lakes through contaminated cargo ships.

The state has been trying to control it since, with 4% of Minnesota waters currently confirmed with zebra mussels.

The spread of Zebra Mussels

Zebra mussels can spread naturally through the flow of water, Adam Doll, the DNR’s invasive species prevention consultant, said. A lake is listed as confirmed if the species has been found in it and listed as connected if the species’ presence hasn’t been found in the waterbody but is a downstream connection to a confirmed lake.

Doll said zebra mussel populations started to increase in 2010 before escalating in 2016 and it’s difficult to determine what caused the spread.

“It’s hard to know if we reached a point where there were enough infested lakes to start quickly spreading from place to place, or was there just more people looking and aware. Minnesota has dedicated a lot of effort to public awareness and education, we have an even more aware populace and they know what they’re looking for,” Doll said.

Minnesota Aquatic Invasive Species Research Center Outreach Specialist Maddie Hayden said zebra mussels are “ecosystem engineers,” as they can alter the entire aquatic ecosystem. Hayden added the mussels eat the same food as baby fish, putting them in direct competition with each other.

“Zebra mussels are efficient filter feeders, (that) leads to clear water, which leads to increased plant growth, which could warm up the ecosystem, and which also impacts our native fishes in the way of recruitment, size, and the amount of mercury within their tissues. That’s like only part of the iceberg,” Hayden said.

By attaching to aquatic equipment, zebra mussels can survive in water found in bait buckets, tanks, motors and other water-containing devices. People moving boats to other bodies of water spread invasive species, Doll said.

The species has spread to multiple Minnesota counties from 1989 to 2024.

As of April 2024, the DNR has confirmed zebra mussels in 311 lakes and wetlands. Otter Tail County and Crow Wing County have the two highest numbers of confirmed lakes in Minnesota.

Doll said these counties get a lot of tourists over the summer, increasing boat transportation and the spreading of mussels in different waterbodies.

Prevention

To stop zebra mussels from entering more lakes in Minnesota, Doll said prevention efforts include cleaning all gear, draining all water, drying everything and dumping live bait in the trash. Minnesota has one of the largest watercraft inspection programs in the country, with over 800 inspectors conducting approximately 500,000 inspections per year, Doll added.

“Minnesota has a state law for boat lifts and docks, the stuff that’s in the water all season long, they have to be out of the water for 21 days before moving to another body of water, and that’s due to the life cycle of zebra mussels, where in right conditions they can live up to three weeks out of the water,” Doll said.

Zebra mussels can attach to the underside of a boat without being caught, causing them to spread to other waterbodies. Courtesy of DNR

At the Minnesota Aquatic Invasive Species Research Center, researchers are working on a form of genetic biocontrol, RNA interference (RNAi), how a gene works in a particular species. For example, they are preventing the gene responsible for the production of byssal thread from being active.

Byssal threads are the structures zebra mussels use to attach to boats or native mussels. If they cannot produce them, hopefully, the zebra mussels will die, Hayden said.

While the southwest corner of Minnesota has fewer confirmed mussel-infested lakes, Scott said he believes it’s only a matter of time before the species affects all lakes.

“I think, sadly, it’s a losing battle, and it’s going to, for better or worse, affect the ecosystem and it’s a new world,” Scott said.

Not everyone agrees with Scott. Hayden encouraged people to look at aquatic invasive species through the lens of conservation. Protecting Minnesota’s water sources is important and can be done by preventing aquatic invasive species from spreading, Hayden added.

“This way of thinking is a lot more poetic than the spread is inevitable. We are trying to solve the world problem one zebra mussel at a time,” Hayden said

More information about zebra mussels and how to stop the spread can be found on the DNR and Minnesota Aquatic Invasive Research Center websites.