Carp Fear

One Asian Carp was found among the tens of thousands of fish killed in Chicago last week.© Chicago Public Radio

In an attempt to keep an invasive species out of the Great Lakes, Illinois conducted a massive fish kill last weekend. How many carps in the catch? One. The lone 22-pounder was among thousands of other fish poisoned in the $3 million project carried out by the Illinois Department of Natural Resources, in order for the Army Corps of Engineers to perform maintenance on an electric barrier in the Chicago Sanitary and Ship Canal that purportedly keeps the aggressive Asian Carp from the Great Lakes.

As the Milwaukee Journal-Sentinel outlined in a 2006 three-part investigative report, an Arkansas fish farmer first imported Asian carp in the 1970s. He turned the unwanted fish (which have been nicknamed "underwater lawnmowers" for their aggressive nature and large and indiscriminate appetites, consuming 40% of their body weight in plankton daily) over to Arkansas fishery officials. "They, in turn, used those fish in sewage treatment experiments that were partially funded by the U.S. Environmental Protection Agency. Those fish were among the first known to have escaped into the wild," the Sentinel recapped in a recent article. Two species of carp, the silver and bighead, have taken over much of the Mississippi, Missouri and Illinois rivers.

Aside from decimating species prized by anglers and commercial fishers, Asian carp, which can grow to four feet in length and100 pounds, are known to "leap from the water at the sound of passing motors and sometimes collide with boaters," according to an article by Caryn Rousseau for the Associated Press.

The poison used in Chicago was rotenone, a broad-spectrum piscicide (as well as insecticide and pesticide) — 2,200 gallons over a five-day period. According to DNR spokeswoman Stacey Solano, rotenone naturally dissipates, but the department will spread another chemical to help accelerate that process. “If used properly there should be no affect to humans or other wildlife,” she said.

Meanwhile, DNA sampling suggests that Asian carp have penetrated the electric barrier and may already be in Lake Michigan.

Sources: Detroit Free Press; Chicago Sun Times; Milwaukee Journal-Sentinel; Associated Press.