Illinois turns to toxin in battle against carp

CHICAGO – Wildlife biologists to Asian carp: It’s on.

Illinois’ Department of Natural Resources launched chemical war Wednesday night against the invasive Asian carp in a 6-mile stretch of the Chicago Sanitary and Ship Canal near Romeoville, Ill., an aggressive response to fears that carp are pushing their way north toward Lake Michigan and could devastate the Great Lakes’ $7 billion commercial fishing industry.

On a cold and windy night beside the canal, fisheries biologists dropped precise quantities of the liquid toxin rotenone from a narrow pipe above the water’s surface. For decades, biologists across the Midwest have used rotenone, a natural chemical, to eradicate or control invasive fish in lakes, ponds and rivers. The toxin dissipates on its own, but officials will add a neutralizing agent to the water to prevent the massive fish kill from spreading beyond the designated area.

The state is applying rotenone while the Army Corps of Engineers works on one of two underwater electric barriers that had been erected to stop the Asian carp from advancing up the canal, a popular corridor for commercial and recreational boaters and the only continuous waterway linking the Chicago and Mississippi rivers. The Coast Guard has shut down that section of the canal above Lockport Dam to boaters until Sunday, when the fish cleanup is expected to be finished.

While rotenone is deadly for fish, officials say it does not pose a threat to humans, animals or other aquatic wildlife. Even so, its use is a dramatic step in the state’s 15-year battle with Asian carp, a large, razor-toothed fish whose voracious appetite and prolific breeding have wreaked havoc on commercial fishing hubs along the Mississippi.

“It’s time to man the barricades,” said John Rogner, assistant director of the DNR. “We’ve simply got to protect the Great Lakes at all costs.”

Biologists made the alarming discovery this year that carp had somehow managed to pass through or bypass the electric barrier, which repels fish with pulsing electric currents. Biologists want to know how many carp have made their way upstream and how far they have gone.

That’s a source of considerable debate among biologists and has sparked concern among officials elsewhere that Illinois and the Army Corps of Engineers have been too lax in battling the Asian carp.