23-Jan-15 – Asian carp DNA in the Chicago River does not worry the Illinois Department of Natural Resources like it used to. They are looking for the entire fish and so far they have been mostly unsuccessful.

When the “eDNA” of Asian carp, or DNA found in the water and not on the fish, started showing up near downtown Chicago about four years ago, the IDNR responded to what it saw as evidence that the large, hungry, and prolific Asian carp was trying to get from the Mississippi River to the Great Lakes. The Chicago River is one of five pathways.

Most recently, on October 20, 2014, the United States Fish and Wildlife Service collected 57 samples from the river and found the DNA of silver carp, a variety of Asian carp, in five of the samples.

In recent years, the IDNR has learned more about eDNA and they have learned more about Asian carp.

“Our understanding of eDNA has changed,” says Kevin Irons (left), manager or the IDNR’s Aquaculture and Aquatic Nuisance Species Program. “We don’t react to eDNA alone.” The Asian carp DNA they are finding in the Chicago River may very well have got there on the hulls of boats or by birds that ate the fish.

“Not only can one meal of carp spread eDNA but the way their digestive system works, it will spread eDNA for a week.”

Irons says the IDNR has been trying to find Asian carp north of electric barriers near Romeoville, Illinois, about 31 miles southwest of Chicago.

“We spent thousands of hours out there with commercial fishers. We caught a bighead carp in Lake Calumet in 2010 but haven’t caught anything since.”

The closest they believe larger numbers of Asian carp have got to Lake Michigan is 55 miles away on the Des Plaines River and that is as close as they will ever get because, says Irons, the carp does not like our small rivers.

Asian carp came here from the Mississippi River, the fourth longest river in the world, but he points out their native habitat is the Yangtze River, the third longest. While there is plenty of food for them on the Chicago River, they seem to lose interest the closer they get.

“They’ll stray up. They’ll go up below the Brandon Lock and Dam. But they don’t seem to linger there. The Asian carp, they’ll go up there and then they’ll turn around and go back downstream.”

(Above) This map by Great Lakes Commission of Illinois waterways near Chicago shows Brandon Lock and Dam in lower left corner and the electric barriers north of there, on the other side of Lockport Lock and Dam. The red dot at upper right marks where the Chicago River meets Lake Michigan.

Since 2010, the IDNR estimates it has removed 160,656 Asian carp from Illinois waterways. In Will County Forest Preserve alone, 900 Asian carp were removed. And they are not taking chances. 32 bighead carp have been removed from landlocked ponds in the Chicago area.