Asian Carp Pose Threat To Illinois Waters, But DNR Is Stepping Up Removal Efforts

Jun 14, 2017

Asian Carp are an invasive group of fish that can compete with native wildlife for food and habitat. The Army Corps of Engineers maintains an electrical barrier to prevent the fish from entering Lake Michigan, but the problem spans all across Illinois. 

Asian Carp were first brought to the United States through aquaculture facilities, or fish farms, as a way to deal with algae in the tanks and make the resulting product tastier. The fish farms often are placed next to rivers for water sources.

Matt O’Hara, Asian Carp Project Leader for the Illinois Department of Natural Resources, said the fish farms are vulnerable to severe weather.

“Those facilities flood," he said, "and the Asian Carp assumedly got out at that point and began their trek upstream into the Illinois River."

That escape took place in the late 70s, introducing the fish to the Mississippi River, and they've migrated northward ever since.  O’Hara said the Illinois River areas most densely populated with Asian Carp are from Grafton to Peoria, with moderate amounts of carp north of Starved Rock. Despite the Department's best efforts, there also is a small population from Morris to Joliet.

DNR works with a variety of agencies to remove the fish that make it to these portions of the Illinois River. One prominent example is the Army Corps of Engineers, which maintains an electrical barrier at the entrance to Lake Michigan. However, O'Hara said the biggest player has been fishermen contracted by the state.

“In 2016 alone, our nine contracted commercial fishermen helped assist and remove over 1.1 million pounds of Asian Carp in the upper Illinois River," he said. "Starved Rock and Marseilles pools were where most of that removal came from.”

These fishermen herd the fish into range with loud sounds, either with underwater speakers or by banging heavy objects against their boats, and use large nets to scoop up the fish. The method isn’t effective against all sizes and varieties of carp, so the U.S. Fish and Wildlife Service is experimenting with new technologies. These include specialized boats known as paupier and doger trawlers.

Video Courtesy of U.S. Fish And Wildlife Service

These craft use an electric shock to stun the fish before bringing them into their nets and can be effective at catching smaller sizes of carp.

No matter the method, however, there is always the chance of native fish being scooped up in the process. O’Hara noted that this bycatch mostly consists of commercial fish like Channel Catfish and Small Mouth Buffalo, which are returned to the river alive.

“We only keep the Asian Carp -- which is Silver Carp, Bighead Carp, and Grass Carp, at this point," he said. "All those fish are brought in and removed. They are also taken by a vendor who is actually making those Asian Carp into an organic liquid fertilizer product.”

However, the fish remain unpredictable. Silver carp are easily startled by motors and can leap into the air, potentially landing in boats or injuring the passengers. Also, once the fish settle down in an area, they pose an ecological threat by competing with native species for common resources. 

Silver Carp are easily startled by loud noises and often jump high into the air when approached by a boat.
Credit Asian Carp Regional Coordinating Committee

Overall, O'Hara believes Illinoisans are well aware of the problem and do a good job at pointing out when carp populations spike.

“There is a general commercial fishing program that’s in the lower river from Starved Rock below, which annually takes out 3 to 5 million pounds of fish annually," he said.  "In all expectations, we would like to see that doubled if not tripled.”

He also claimed the carp, despite its boniness, is quite edible. However, DNR’s operations are only part of the greater effort against Asian Carp. At the higher levels are the Army Corps of Engineers, whose barrier at the entrance to Lake Michigan prevents Asian Carp from entering the Great Lakes System. And down below, O’Hara says it ultimately comes down to education.

The U.S. Army Corps of Engineers maintains a series of electrical barriers in the Chicago Sanitary and Ship Canal near Romeoville. They are the last line of defense against Asian Carp entering Lake Michigan.
Credit U.S. Army Corps of Engineers

“Make sure your bait bucket is drained and doesn’t have anything left in it after you leave a body of water that you may have fished in. We don’t want the spread of any kind of aquatic nuisance species.”

You can find more information about Asian Carp from the Asian Carp Regional Coordinating Committee.