Bighead carp DNA found in Milwaukee River for the first time – Milwaukee Journal Sentinel

For the first time, bighead carp DNA has been found in the Milwaukee River, according to the U.S. Fish and Wildlife Service.

Thegenetic material, called environmental or eDNA, was detected in a water sample taken in June during routine sampling on the river.

Thetest resultwasconfirmed Friday by the Service and the Wisconsin Department of Natural Resources.

Bighead and its close relative thesilver carp are highly destructive, invasive species of carp spreading throughout North American waters.

To date, no live specimens of the fish have been found in the Wisconsin waters of Lake Michigan or its tributaries.

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But fisheries biologists have been on the lookout due to the threat the carp pose to the multibillion-dollar fishery.

The Service uses the highly sensitive eDNA methodologyas part of its annual monitoring for invasive species in the Great Lakes.

The testingis designed to detect traces of skin cells, feces, reproductive secretions and other genetic material shed into the environment.

While DNA from the invasive fish canenter lakes and rivers in wastewater or other indirect means and doesn't necessarily signal the presence of a live fish, a positive testsends off an alarm, said Nick Frohnauer, USFWS eDNA and early detection and monitoring coordinator.

"We can't be sure of the source," Frohnauer said. "But people should have a heightened sense of concern for Lake Michigan and the Great Lakes overall because of how close the carp are in the river systems and the damage they can cause."

The positive bighead carp result came from one out of 100 samples taken from the Milwaukee River, according to the Service.

Silver and bighead carp are found in theChicago Sanitary and Ship Canal, about 35 miles from Lake Michigan. They are also found in Wisconsin waters of the Mississippi and St. Croix rivers.

And in 2020 the DNR brought charges against a Wisconsin man for illegally transporting the carp into the state and selling them in Madison.

The finding of invasive carp DNA in theMilwaukee River marks the third such detection in Wisconsin waters of Lake Michigan.

Silver carp DNA was found near Sturgeon Bay in 2013 and bighead carp DNA was found in the Fox River in 2014, according to state and federal biologists.

Subsequent netting and electroshocking in both areas failed to turn up a silver or bighead carp, dead or alive.

The Milwaukee River detection will trigger a similar response, saidTodd Kalish, DNR deputy fisheries director.

Additional water samples were collected this week, Kalish said, and beginning next week crews will use nets andshocking gear to search for invasive carp on the Milwaukee.

The eDNA results on the additional water samples are expected to be known later this month, according to Kalish.

Bighead, black, grass, and silver carp were imported from Asia to the United States in the 1970s as a method to control nuisance algal blooms in wastewater treatment plants and aquaculture ponds as well as for human food, according to the U.S. Geological Survey.

Within 10 years, the carp escaped confinement and spread to the waters of the Mississippi River basin and other large rivers like the Missouri and Illinois.

The invasivecarp are filter feeders that remove large quantities of plankton from the water and competewith native aquatic species for food and habitat.

Their rapid population increase is disrupting the ecology and food web of the large rivers of the Midwest, according to the USGS.

In areas where bighead and silvercarp are abundant, they have harmed native fish communities and interfered with commercial and recreational fishing.

Bighead carp can get very large. A 125-pounder was taken this summer by a bowfisherman in Missouri.

Kalish said it was criticalto keep bighead and silver carp out of the Great Lakes to help protect the region's estimated $7 billion-a-year fishing industry.

"I can't overemphasize how important it is to be vigilant and work to prevent the spread of these invasive carp," Kalish said. "We hope this DNA finding doesn't lead to finding a fish. But no matter what, it helps underscore this critical issue and the need to work together to keep these invasivesout."

Invasive carp info: It is a violation of federal law to transport live Asian carp in interstate commerce. In addition, Wisconsin law makes it illegal to possess, transport, transfer or introduce any species of live Asian carp.

If you catch or find a bighead, black, grass or silver carp in Wisconsin, the DNRadvises you to not return the fish to the water. Instead, take a photo of the fish andreport it to the DNR. If possible, put the fish on ice and take it the local DNR office.

For more information, visit dnr.wi.gov andinvasivecarp.us.

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Bighead carp DNA found in Milwaukee River for the first time - Milwaukee Journal Sentinel