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Invasive fish species still swims Mississippi River. There’s a reward if you catch one

Black carp, such as the one seen collected from a lake in the middle Mississippi River in Alexander County, Ill., are invasive to North America and threaten important native species.
U.S. Fish and Wildlife Service
Black carp, such as the one seen collected from a lake in the middle Mississippi River in Alexander County, Ill., are invasive to North America and threaten important native species.

Editor's note: This story was originally published in the Belleville News-Democrat.

Hundreds of black carp have been reported in the Mississippi River basin, and the invasive fish harm the local ecosystem by threatening important native species.

A study released in December by researchers from Southern Illinois University, the U.S. Geological Survey, the U.S. Fish and Wildlife Service, Missouri State University and the Missouri Department of Conservation found black carp have been established in the Mississippi River basin.

Black carp are native to eastern Asia and were introduced to the U.S. in the 1970s and 1980s in imported, contaminated grass carp stocks shipped to private fish farms, according to the USFWS.

“The use of black carp in these types of aquatic environments is regulated and requires permits, and there isn’t a clear understanding on how black carp escaped those settings,” the December USGS release said.

The USGS maintains an online database of nonindigenous aquatic species, including black carp. The species has been reported in the Mississippi River, as well as Kaskaskia River, Horseshoe Lake, the Illinois River, Ohio River and more.

Some reports may represent multiple fish, and not all the reports are recent. The database shows reports at least as far back as 2013. Not all reports denote an established population of the species.

Between the Mississippi River, the Ohio River, the Illinois River and Horseshoe Lake, there have been 58 reports of black carp so far this year added to the database. There have been 1,038 reports of black carp added to the database since 2013, including sightings in the Mississippi River and other bodies of water.

While black carp have been reported in the U.S. for years, the December study was the first time researchers have been able to produce strong evidence showing the species has established itself in the Mississippi River or anywhere else in the country, Patrick Kroboth, research fish biologist with the U.S. Geological Survey, told the News-Democrat.

“They’re present in the wild … they’re reproducing, they’re living to adulthood, those are some of the kind of benchmarks we’ve measured,” Kroboth said.

Here’s what to know about how black carp could harm the Mississippi River ecosystem and what should you do if you happen to reel one in.

What makes black carp invasive?

Invasive species are non-native life introduced to the environment. They spread and have the potential to harm human health, the environment or the economy, according to USGS.

Black carp compete with indigenous species for resources and pose a direct threat to native mollusks, researcher Kroboth told the News-Democrat.

Nearly 70 freshwater mussels are native to Missouri, and native mussels generally provide water filtration services to the Mississippi River, Kroboth said.

Mussels feed by filtering out particles from the water, and they can also provide a habitat for other species to attach to.

“Mussels support ecosystem health by improving water quality — they filter out bacteria, algae and pollutants as they breathe and feed — and provide food and nutrition for other species,” the USGS release said.

Black carp feed on mussels and snails, and many of the region’s native mussels are already threatened or imperiled, Kroboth continued.

What should you do if you find a black carp?

Because the species is invasive, live possession of black carp is illegal.

Those who catch a black carp should follow the “keep, cool, call” protocol, the USGS says. Fishers are asked to identify the species, keep it, note the location where it was found and take photos of the fish. People who catch black carp should “humanely kill” them, the USGS advises, and keep it cool on ice (but don’t freeze it unless necessary).

Next, report the fish to local authorities. The USGS provides a contact list with email addresses and phone numbers that vary based on where the fish was caught. Officials ask people to call, as well as email photos of the fish.

If you take the time to turn in any black carp you catch, you may be eligible for a $100-per-carcass bounty, funded by the Illinois Department of Natural Resources.

Reimbursements are limited to 10 awards per person per month and are subject to funding availability. Funding has run out before, according to a July 2022 report from WKDQ.

Species such as grass carp and common carp are often misidentified as black carp. The keep, cool, calm document provides more information about distinguishing black carp from other species.

Meredith Howard is a reporter with the Belleville News-Democrat, a news partner of St. Louis Public Radio.

Meredith Howard is a service journalist with the Belleville News-Democrat in Belleville, Illinois.