Environmental officials say they have found a single Asian carp in a canal leading to Lake Michigan — the closest any of the giant fish have come to the Great Lakes.
Environmentalists fear the Asian carp could starve out other fish and devastate the $7 billion-a-year Great Lakes fishing industry.
Department of Natural Resources assistant director John Rogner says the single fish was found Thursday among tens of thousands of other species scooped up during a kill operation in the Chicago Sanitary and Ship Canal.
Authorities dumped a toxin into the canal Wednesday to eliminate any carp while an electrical barrier designed to keep them out of the Great Lakes was turned off for maintenance.
Environmentalists fear that the fish, which consume up to 40 percent of their body weight daily in plankton, could starve out smaller and less aggressive competitors and cause the collapse of the $7 billion-a-year Great Lakes sport and commercial fishing industry.
The carp — which can grow to 4 feet long and 100 pounds and are known for leaping out of the water when boats are near — were imported by Southern fish farms but escaped into the Mississippi in large numbers during flooding in the 1990s and have been making their way northward ever since.
Scientists say more than 180 invasive species have entered the Great Lakes, multiplying rapidly and feeding on native species or competing with them for food. Millions of dollars have been spent trying to control the zebra mussel and the round goby fish, which already have moved between the Great Lakes and Mississippi River basins.
The Mississippi and the Great Lakes are connected by a complex, 250-mile network of rivers and canals engineered more than a century ago. It runs from Chicago, on the southern edge of Lake Michigan, to a spot on the Mississippi just north of St. Louis.
Tens of millions of tons of goods are moved annually along the shipping canals or through the locks that lead into Lake Michigan.
In the continuing struggle to keep the fish out, Illinois environmental officials began dumping poison Wednesday night in a nearly six-mile stretch of the Chicago Sanitary and Ship Canal near Lockport.
Crews then planned to use large cranes with nets to scoop up an estimated 200,000 pounds of dead fish, which were to be taken to a landfill.
The electrical barrier, which was installed in 2002 to repel fish with a non-lethal jolt, has long been the only thing standing between the carp and Lake Michigan, the gateway to the four other lakes. But officials said two weeks ago that DNA from Asian carp had been found between the barrier and one of the locks on the lake. No actual carp have been found in Lake Michigan.
Environmentalists and Michigan Gov. Jennifer Granholm said the locks should be closed while the scope of the problem is established.
"This is an immediate threat to the Great Lakes, to our sport and commercial fishery, and as such it requires some emergency actions appropriate to the level of that threat," said Ken DeBeaussaert, director of Michigan's Office of the Great Lakes. "Closing the locks to prevent the possible spread of the Asian carp into the Great Lakes is an appropriate response on an emergency basis."
Environmental groups also said the government should find a way to permanently separate — through physical barriers or other means — the Great Lakes and Mississippi watersheds so the invasive species has no way of passing between the two.
Last fall, environmental groups offered several possible solutions, including erecting concrete walls, constructing more locks, even lifting barges over the locks.
The issue "takes on a whole new urgency because of the Asian carp emergency," said Andy Buchsbaum of the National Wildlife Federation. "We don't know where the carp are, and the risk of their being in the canals is too great."