Havana, Ill. — A TV reporter from Chicago recently visited this stretch of the Illinois River to see something firsthand: Asian carp are more abundant in Havana than any place else on earth.
For two decades, state experts have been tracking Asian carp numbers in the waters around the river town.
“We’re 200 miles from Lake Michigan and about 120 miles up from the Mississippi,” Kevin Irons, Asian carp program director for DNR, told Nancy Loo of WGN-TV. “You find more carp per acre, per mile of river than nearly anyplace else in the world.”
Right now, the community is about 60 percent Asian carp. Irons says native species have thinned out.
“There’s not enough food to go around,” Irons explained.
DNR’s team tests known hotspots on the Illinois River and tributaries to check for changes, documenting with their own video for analyzation and comparison. Matt O’Hara, Asian carp project leader for DNR, noted that it’s “pretty distressing when you come out here and you’re looking for native fish, and all you see is invasive Asian carp.”
Experts sketch a nightmare scenario in which the carp could eventually eliminate most other fish species from the Great Lakes, which is why a host of agencies and researchers are urgently searching for ways to slow them down. Their ideas range from the conventional (paying bounties to fishermen) to the downright weird (water guns that shoot bubbles), and from the scary (poison particles and electric barriers) to the potentially tasty (eating carp into submission).
Some of those ideas are in a 232-page report released earlier this year by the U.S. Army Corps of Engineers detailing an $18 billion plan to keep out invasive carp, along with 11 other Great Lake threats such as invasive zebra mussels. But that plan would take decades to implement, and no one knows where the money will come from – or whether it will succeed at keeping the carp out.
“This is a big deal,” says James Garvey, a fish ecologist and professor at Southern Illinois University in Carbondale. “We’ve connected watersheds that were not connected before. Now species have a pathway between Lake Michigan and the Mississippi.”
Of the four Asian carp species in U.S. waters, only two can be held culpable for ecological destruction. Outside of the retention ponds they were expected to keep clean, bighead carp and silver carp are the ones we label invasive, and their all-you-can-eat-buffet mentality leaves little for other organisms to feed on.
Native filter feeders such as paddlefish, gizzard shad, and big mouth buffalo face major competition for scoring a meal of rotifers and other plankton.
So far, control efforts have focused on a tried and true method: fishermen. At SIUC, Garvey and his team found that using contracted anglers to harvest the carp helped temporarily, but that the fish replenished themselves easily.
The USGS, meanwhile, is thinking outside the box by trying to develop innovative technologies that could really get under the skin of Asian carp.