Researchers working to combat common carp in Minnesota

Efforts to remove invasive carp from waterways across Minnesota have been ongoing for more than 100 years, but researchers say they've made strides in learning about the destructive fish over the past decade.

These days, controlling the unwanted fish is a more realistic goal. Individual fish have been found in various locations moving north in the upper Mississippi, for example. The farthest north discovery came in August 2013, when a fisherman discovered the body of a silver carp on a dam abutment near Lock and Dam 5.

Some research being done in lakes north of the Twin Cities is helping advance that work. Research and management efforts in a system of lakes connected to Rice Creek in Lino Lakes involve year-round tracking of adult common carp equipped with electronic tags.

University of Minnesota graduate student Nate Banet is involved in the National Science Foundation-funded project led by Peter Sorensen, fisheries professor and founder of the Minnesota Aquatic Invasive Species Research Center at the university.

"We've found some pretty remarkable stuff doing that," Banet said. "We found some fish travel over 8,000 meters through four different lakes — that's over four miles this fish traveled in a 24-hour period."

While some other fish, like northern pike, also migrate in the spring to spawn, common carp live longer and can continue the cycle for more than 50 years, he said.

The Rice Creek Watershed District hopes to use the research on carp migration to cut off their movement and reduce their population.

Simply fishing carp out of the lakes proved ineffective a few years ago when commercial fishermen removed about 180,000 pounds of carp from Long Lake, said Matt Kocian, lake and stream specialist for the watershed district.

"It sounds like a big number, but you can't really put it in perspective until you see it," he said. "It is 30,000 to 40,000 fish. We thought, great, we probably got a big portion of the population in that catch. Lo and behold, he comes back the following winter and captures another 180,000 pounds of carp."

But the watershed district plans to continue using trap nets as one of the tools to combat the common carp population.

"In order to get that long-term sustainable management that we really want, we're going to have to find some other tools to mix in with that," Kocian said, "whether it's a barrier, whether it's aeration, whether it's stocking game fish."