20 January 2024
After netting its largest-ever catch of invasive carp in the Mississippi River in November, the Minnesota Department of Natural Resources is moving ahead with a revised plan to keep the bottom-feeding fish from spreading across the Land of 10,000 Lakes.
DNR officials on Thursday unveiled a revised carp management plan that includes increased research and monitoring as efforts continue to track the carp’s northward advance using radio telemetry.
The plan also calls for increased physical barriers to stop the carp, especially at several lock and dam facilities on the Mississippi River, some as far south as Keokuk in southeastern Iowa, upstream of which there has been little sign of carp reproduction. DNR officials said they continue to research a carp barrier at lock and dam No. 5 in Minnesota waters, but said it remains unclear if or when the state will move forward with a barrier.
The DNR plan calls for increased agency netting while also recruiting more commercial netters to remove the carp, potentially offering a bounty for each carp caught. Biologists say there is little evidence the big fish are reproducing in Minnesota or Wisconsin waters yet, so removing as many adults as possible before they can breed here should help to keep their numbers in check.
The plan also suggests finding new ways to use netted carp, such as fertilizer or pet food, to add value and encourage more netting, although officials said there aren’t enough carp this far north to make that financially viable at this time.
“Today’s updated action plan is a road map that will guide the DNR’s work with our partners and all Minnesotans to minimize the impact of silver, grass, bighead and black carp on our state,” DNR Commissioner Sarah Strommen said Thursday in a statement announcing the plan.
The 2023 Minnesota Legislature gave $1.7 million to the DNR to prevent and manage invasive carp. The DNR used some of those funds to pay for increased commercial fishing. Commercial fishing has also been supported by invasive carp grants administered by the U.S. Fish and Wildlife Service and the state’s Environment and Natural Resources Trust Fund.
But the DNR plan also notes that more money will be needed to keep up the fight and try new strategies.
“Invasive carp have the potential to impact native aquatic communities, local economies and Minnesota’s outdoor heritage,” the agency noted in releasing the carp plan. “The key purpose of this plan is to slow the spread of invasive carp, minimize their impact and reduce the likelihood of invasive carp reproducing in Minnesota waters.”
DNR officials also are looking at how to stop carp invasions caused by floods when the fish can potentially breach dams, locks and other barriers and move into inland waterways not directly connected to the Mississippi, Minnesota or St. Croix rivers.
Invasive carp from top to bottom: silver carp, bighead carp, grass carp and the common carp. (Courtesy of the University of Illinois)
Formerly called Asian carp after the region where they were native, the invasive silver, grass and bighead carp have been moving up the Mississippi River system for decades. They have been found as far north as the Twin Cities in the Mississippi and St. Croix rivers. There’s little hope of exterminating them from big river systems, but it’s hoped that natural and human-made barriers, like waterfalls, locks and dams, will keep them from advancing farther upstream. Additional barriers could include electric currents, sound and other disturbances to turn the fish back downstream.
In 2014, Congress authorized closing the lock at Upper St. Anthony Falls in Minneapolis and it was closed permanently in June 2015 to prevent the spread of invasive carp upstream past that point in the Mississippi River. Taylors Falls should keep them from moving up the St. Croix River.
Still, officials say it wouldn’t take much for the invasive fish to be intentionally or accidentally moved into other waterways across the region, much as other invasive species have been spread by humans.
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The bottom-feeding carp were imported to the U.S. in the 1960s and 1970s to help rid southern aquaculture farms of algae, weeds and parasites. They escaped through flooding and accidental releases, found their way into the Mississippi River and have used it as a superhighway to spread north into rivers and streams in the nation’s midsection.
Bighead carp can grow to 100 pounds and the invaders are voracious eaters — adult bigheads and silvers can consume up to 40% of their body weight in a single day.
They easily out-compete native species, wreaking havoc on aquatic ecosystems. The fish also are known for their ability to jump out of the water, including when they spook from passing motorboats.
Biggest catch ever
Invasive silver carp, which are native to Asia, in the Illinois River. The carp, which tend to jump out of the water when disturbed by motorboats, have been moving up the Mississippi River system for decades and also threaten to enter the Great Lakes near Chicago. (Courtesy of the U.S. Fish & Wildlife Service)
In early December, the Minnesota and Wisconsin departments of natural resources announced they had netted more carp than had been found in Minnesota waters all previous years combined — including 296 silver carp, 23 grass carp and four bighead carp — in the Mississippi River just downstream of Winona, Minn. It was the largest single capture of invasive carp that far north to date.
The Wisconsin DNR tracked six tagged invasive carp in that area of the river, which led officials to larger schools moving upstream. Observations from commercial anglers also helped DNR crews pinpoint the fish.
Great Lakes barrier coming in 2024
Meanwhile, the fish are threatening to enter the Great Lakes near Chicago after swimming out of the Mississippi River and up the Illinois River system. Federal officials have pledged construction this year of a $1.1 billion barrier at Brandon Road Lock and Dam along the Des Plaines River in Joliet, Ill., to keep the fish from gaining a foothold in Lake Michigan waters.
That project, which has been delayed for years, will use noisemakers, a bubble curtain, an electric barrier and a flushing lock to prevent carp from passing.
If you catch an invasive carp
Invasive carp captures — not including the common European carp — must be reported to the Minnesota DNR immediately.
Take a photo and make arrangements with the DNR to transport the carp to the nearest fisheries office.
Call 651-587-2781 or email [email protected].
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