Invasive silver carp found in St. Croix River for first time
PRESCOTT, Wis. — 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 March 10 by a commercial fishing boat, according to the Minnesota Department of Natural Resources, which announced confirmation of the catch Thursday.
Silver carp are notorious for their proclivity to leap 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 rivers at Prescott, Wis. Silver carp already had been found farther upstream in the Mississippi, 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.
"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."
Biologists have not yet uncovered evidence of a reproducing population of either species in the metro waters — a key distinction in their strategy to slow their invasion.
"The location where the carp were captured is a well-known over-wintering area for several species of fish," Frohnauer said in a news release. "At this time, it is hard to predict if these individuals would have moved (farther) upstream the St. Croix River, or back into the Mississippi River when water temperatures warm up in the spring."
The silver carp caught on the St. Croix measured 33 inches long and weighed 13 pounds. One bighead carp was also caught by the commercial angler, who was working with a DNR fisheries biologist, the DNR said.
Once the ice clears, DNR workers and commercial anglers plan to survey for additional invasive carp near Prescott.
The DNR will also sample at the Allen S. King Power Plant near Bayport, where bighead carp have been caught in the past. A commercial angler netting under the ice near the Bayport marina earlier this year did not catch any invasive carp.
Farther upstream, the dam at Taylors Falls, Minn., is thought to be an adequate barrier to prevent the carp from penetrating deep into eastern Minnesota and northwest Wisconsin. Along the Mississippi, however, dams from St. Paul south have locks used for boats — a system that the carp could use as well.
The Minnesota Aquatic Invasive Species Research Center at the University of Minnesota is testing carp deterrents in Mississippi locks and dams. Biologists have installed acoustic speakers at Lock 8 and modeled flows through the gates at dams 2 and 8.
According to the DNR: Invasive carp have been progressing upstream since escaping into the Mississippi River in the 1970s. The large fish compete with native species and pose a threat to rivers and lakes.
Invasive carp captures must be reported to the DNR immediately. Call 651-587-2781 or email firstname.lastname@example.org. 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 mndnr.gov/invasivecarp or attend the upcoming invasive carp stakeholder forum 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, at 651-259-5670 or email@example.com.
The Pioneer Press is a Forum News Service media partner.