Wildlife officials discovered a single Asian carp Thursday in a canal leading to Lake Michigan, the nearest the destructive species has come to the Great Lakes, Illinois environmental officials said.
Environmentalists fear that if the silver or bighead species of giant Asian carp reach the lakes they could starve out native fish species and devastate a $7 billion-a-year fishing industry.
U.S. Fish and Wildlife Service officials found the 22-inch immature specimen among tens of thousands of dead fish identified in a fish kill operation in the Chicago Sanitary and Ship Canal, about 40 miles from Lake Michigan, said John Rogner, assistant director of the Illinois Department of Natural Resources.
"Asian carp are indeed knocking on the door of the Great Lakes," Rogner said "This is the closest to Lake Michigan that an actual Asian carp body has been found."
Ten of thousands of other species of fish, from gizzard shad to drum, floated to the surface of the waterway Thursday after authorities dumped more than 2,000 gallons of toxins into a nearly six-mile stretch of the waterway the evening before.
The toxins were dumped while an electrical barrier normally used to prevent any Asian carp from the Great Lakes was turned off for maintenance. The kill operation -- which will require the removal of an estimated 200,000 pounds of dead fish to a landfill -- began Wednesday and was expected to last until Saturday.
The Asian carp -- which can grow to 4 feet -- were imported by Southern fish farms but escaped into the Mississippi River in large numbers during flooding in the 1990s and have been making their way northward ever since. No Asian carp have yet been found in Lake Michigan.
Concern about the silver or bighead species of Asian carp led to calls even before Thursday to close the waterway connecting the lakes to the Mississippi -- an unprecedented step that could disrupt the movement of millions of tons of coal, grain and other goods.
The electrical barrier, installed in 2002 to repel fish with non-lethal jolts, had been thought to be the only thing standing between the carp and Lake Michigan. Officials said two weeks ago that DNA from Asian carp had been found between the barrier and a lock near the lake.
Michigan Gov. Jennifer Granholm and five environmental groups have threatened to sue the U.S. Army Corps of Engineers to force it to temporarily shut three shipping locks near Chicago because of evidence the Asian carp may have breached the electrical barrier. The agency has said it would consider all options but would not close the locks without first studying the possible effects.
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