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Invasive Asian carp confirmed in St. Croix River

Invasive carp, like the one pictured here, have been confirmed in the St. Croix River, according to the Minnesota Department of Natural Resources. (Minnesota DNR photo)

For the first time, an invasive silver carp has been captured in the St. Croix River.

The carp, one of several invasive species of so-called “Asian carp,” was caught Friday, March 10, by a commercial fishing boat this month, according to the Minnesota Department of Natural Resources, which announced confirmation of the catch Thursday.

Silver carp are the most notorious because of their proclivity for leaping out of the water when boats approach. They’re also regarded as a major threat to native species and the state’s deep love of fishing.

But St. Croix lovers shouldn’t fear the carp-pocalypse quite yet.

The fish was found near the confluence of the St. Croix and the Mississippi River at Prescott, Wis. Silver carp already had been found in the Mississippi upstream from the confluence, and biologists have long suspected fish would swim unimpeded up the St. Croix and be detected sooner or later.

Bighead carp — another prominent invasive Asian carp — have been found in those waters as well.

Biologists have not yet uncovered evidence of a reproducing population of either species in the metro waters.

“This news is disappointing but not unexpected,” said DNR invasive fish coordinator Nick Frohnauer. “The silver carp was captured within viewing distance of the St. Croix’s confluence with the Mississippi River. In 2014, two silver carp were found in the Mississippi only a short distance upstream from where the St. Croix and Mississippi meet.”

The following comes from a news release from the DNR:

The silver carp caught on the St. Croix was 33 inches long and weighed 13 pounds.

One bighead carp was also caught by the commercial angler, who was working in conjunction with a DNR fisheries biologist. Bighead carp have previously been caught at this same location and further upstream on the St. Croix.

Frohnauer noted that while the DNR is concerned about the potential impacts of invasive carp in the St. Croix River, the individual fish that have been captured do not indicate reproduction or an established population of either bighead or silver carp in the St. Croix.

“The location where the carp were captured is a well-known over-wintering area for several species of fish,” Frohnauer said. “At this time, it is hard to predict if these individuals would have moved further upstream the St. Croix River, or back into the Mississippi River when water temperatures warm up in the spring.”

Immediate follow-up sampling was not possible on the St. Croix, as colder weather led to the river icing up. Once the ice clears, DNR staff will work with commercial anglers to survey for additional invasive carp near Prescott.

Additionally, the DNR will sample at the King Power Plant near Bayport, Minn., where bighead carp have been caught in the past. A commercial angler netting under the ice near the Bayport marina early in 2017 did not catch any invasive carp.

The DNR Invasive Species Program has built partnerships with state and federal agencies, conservation groups, university researchers and commercial businesses collaborating to prevent the spread of invasive carp:

The DNR is an active partner in the Upper Mississippi River invasive carp workgroup, which is working to limit the impact of invasive carp. The group includes representatives from Minnesota, Wisconsin, Iowa, Illinois, Missouri, and several federal agencies.

In partnership with the DNR, the Minnesota Aquatic Invasive Species Research Center at the University of Minnesota is testing carp deterrents in Mississippi River locks and dams. They have installed acoustic speakers at Lock 8 and modeled flows through the gates at dams 2 and 8.

DNR fisheries leads a comprehensive sampling program to monitor population expansion, population changes, and impacts of management actions. As part of this partnership with the commercial fishing community, a DNR field biologist was on site when the commercial angler captured the silver carp and bighead carp on the St. Croix.

The deterrent testing and sampling programs have been funded by the Environment and Natural Resources Trust Fund with proceeds from the state lottery.

Invasive carp have been progressing upstream since escaping into the Mississippi River in the 1970s. These large fish compete with native species and pose a threat to rivers and lakes. While no breeding populations have been detected in Minnesota waters, individual fish have been caught in the Mississippi near the Twin Cities, the St. Croix River and the Minnesota River.

Invasive carp captures must be reported to the DNR immediately. Call 651-587-2781 or email Take a photo and transport the carp to the nearest fisheries office or make arrangements for it to be picked up by a DNR official.

To learn more, visit, and attend the upcoming invasive carp stakeholder forum Wednesday, March 29, at the Minnesota Valley National Wildlife Refuge visitor center in Bloomington from 9 a.m. to 12:30 p.m. For additional information about the forum, contact Nick Frohnauer, DNR invasive fish coordinator, 651-259-5670,

The St. Paul Pioneer Press is a media partner with Forum News Service and RiverTown Multimedia