An invasive species of Asian carp has been found just downstream of the Indiana state line. If left unchecked, the black carp could pose a threat to native species in Hoosier waterways.

Two black carp were caught in the Ohio River just 10 miles from the border, causing the Indiana Department of Natural Resources to sound the alarm about the fish. Black carp have already devastated species of critically endangered mollusks, the fish’s favorite food, across the Mississippi River basin.

Black carp were first introduced to the United States in the 1970s and ‘80s as one of four Asian carp species in captivity.

Some of the fish eventually slipped into waterways and have been multiplying throughout the Mississippi River basin. Black carp have been confirmed in the White River in Arkansas, the Atchafalaya and Red rivers in Louisiana and the Kaskaskia and Illinois rivers in Illinois.

Black carp can eat as much as four pounds of mussels per day, according to the DNR. The fish feed on 26 species of rare native mussels, including 10 on the federal endangered species list.

Along with the potential to wipe out species already endangered by pollution and alterations to waterways, a large population of mollusk-eating fish could interrupt the mussels’ natural regulation of the state’s rivers, lakes and streams.

Mussels act as filters, removing suspended materials from the water. They stabilize the bottom of a body of water by burrowing, which increases oxygen exchange, according to the DNR.

Mollusks also help stabilize water ecosystems by provided food for other species.

Most mussels cannot survive in polluted water. Researchers can measure levels of contamination in waterways by testing mollusk shells.

Along with further harming native mussel populations, black carp host parasites, flukes, bacteria and viral diseases, all of which can attack native species. Black carp will “inevitably reduce the biodiversity of our waters,” a DNR news release said.

The U.S. Fish and Wildlife Service lists the black carp as an “injurious” fish species. This designation prohibits importation of black carp into the U.S. as well as interstate transport of the fish.

“If an established population would be found in the wild it would be almost impossible to eradicate,” the DNR release said.

In preparation for a potential infestation of the Great Lakes region, the Illinois-Indiana Sea Grant is working with stakeholders across the region to spread information about black carp and three other invasive species of Asian carp.

“Asian carp have already caused enormous damage in the Mississippi River basin, and we don’t want to see them in the Great Lakes,” said Reuben Keller of the Institute of Environmental Sustainability at Loyola University Chicago.

The Illinois Department of Natural Resources is offering a $100 bounty for confirmed black carp carcasses.

Black carp look similar to grass carp, according to the DNR, with subtle differences. For instance, black carp tend to have longer pectoral fins than grass carp.

Black carp are black, blue gray, or dark brown and the fins, in particular, are darkly pigmented. In contrast, grass carp are olive or silvery white, or olive brown on top with silver bellies and dusky-colored fins.

If you catch one

Black carp can be caught using traditional baits, but bow-fishing anglers are more likely to encounter them.

If you think you've caught a black carp, the Indiana Department of Natural Resources advises the following:

• Keep the fish and make note of its location.

• Cool the fish on ice after you've killed it.

• Call the DNR at 1-866-663-9684 to report the fish.

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