Skip to main content

Here's why the DNR put an invasive carp back in the St. Croix

It's part of the fight to keep the fish out of the state

The fight to protect Minnesota waters from invasive carp normally means killing off the fish whenever one shows up. Right now, though, state biologists are trying something different.

When they caught a 37 pound bighead carp in the St. Croix River last week, they did a little surgery on it and returned it to the water. 

Now the fish has a four-inch long transmitter implanted in it. And every day scientists are tracking where that fish goes. The Department of Natural Resources says learning more about the range and behavior of the invasive fish will help them get better at catching them and keeping them out of Minnesota's rivers and lakes. 

After a few weeks they'll catch it again (that'll be pretty easy since they know exactly where it is). That time they'll kill it and cut it open to see if it's a female with eggs.

Special permission from the Legislature

Releasing an invasive species into the water is against the law in Minnesota, so the DNR had to get special permission for this from the Legislature. 

The agency says the bighead they're tracking on the St. Croix now is their first use of the new technique. 

Biologists tested the catch-implant-release-track-recapture system last summer on a Mississippi River fish similar to invasive carp (the bigmouth buffalo) to make sure the concept worked. 

How will this help?

Invasive carp – which include bighead, silver, and grass carp – are pretty rare in Minnesota, with just a few reported per year. As far as we know they aren't breeding in the state. That's good because in places where they get established invasive carp damage the native fish by hogging up most of the food and space.

Nick Frohnauer, the DNR's invasive fish coordinator, tells MPR News tracking the invaders that do show up will teach researchers more about the fish. 

"Previously when we captured a fish we only knew that the fish was there at that specific time," he says. "We didn't know if it was hanging out there or passing through, where it came from or where it was going. This will help us gain that."

The DNR already has a network of 70 acoustic receivers, mostly in the Mississippi, and they're expanding that with money from the environmental trust fund that operates with State Lottery proceeds.

Anyone who catches an invasive carp while fishing should contact the DNR at 651-587-2781 and arrange to either bring it to a fisheries office or have it picked up. 

Next Up

grinch neighbor

Neighborhood 'grinch' sends letter to Burnsville family over holiday lights

A Burnsville family's holiday decorations were the subject of an anonymous complaint.


Anthropologie shutters Grand Avenue store, opening planned for Rosedale Center

The popular holiday shopping weekend marked the last for customers of the Grand Avenue store.

hospital, emergency room

Woman found on side of highway after hit-and-run

The 41-year-old was airlifted to a hospital with life-threatening injuries.

Jorden Nicole Borders

Charges: Minnesota woman tortured her kids, removed boy's blood

Warning: This story contains upsetting content.

first snow

Will narrow band of 6+ inches of snow hit Twin Cities Tuesday?

The NWS says a band of 6+ inches is looking likely. It's now a matter of where.


Siblings, ages 19 and 14, killed in crash on icy MN highway

The crash happened around 1:15 a.m. Saturday in Carlton County.

Nicholas Kraus

Man sentenced for fatally striking woman during Uptown protest

Nicholas Kraus, 36, of St. Paul drove into a protest in Uptown last year, killing Deona Marie Knajdek.

Flickr - police lights squad siren - Edward Kimmel

Fleeing suspect crashes into vehicle in Woodbury, 2 injured

The crash occurred Friday afternoon after a pursuit with Woodbury police.

Screen Shot 2022-11-26 at 2.34.44 PM

Yes, that's MN native Jenny Taft in a State Farm commercial

Jenny Taft got her broadcasting career started in Minneapolis in 2011.

crime scene tape - police tape

23-year-old woman critical after shooting in Plymouth

A 23-year-old woman was shot Friday night in Plymouth.

white Christmas

2 MN towns among most 'magical' winter locations in the country

The list was compiled by Trips Discover and published earlier this month.

Screen Shot 2022-11-26 at 8.27.12 AM

St. Olaf football player charged after fatal crash in Chicago

The 18-year-old is accused of speeding and going the wrong way when he crashed into a vehicle that may have been attempting to flee police.


Federal leader of Asian carp fight focused on Great Lakes, skeptical of Miss. River plan

The Obama administration's point man in the fight against invasive Asian carp says his agency is focused on protecting the Great Lakes. But he doubts the plan Sen. Amy Klobuchar is pushing is a viable way to keep the fish out of the upper Mississippi River.

Policymakers see St. Anthony Falls as line in sand in fight against Asian carp

State and federal officials are pushing a bill in Congress that would close the lock and dam at St. Anthony Falls if the invasive fish is found nearby. They say if Asian carp get any farther up the Mississippi River, they would threaten Minnesota's $11 billion tourism industry.