Fears over giant carp decimating fish stock in the Great Lakes

Chicago: Fears that giant, voracious species of carp will get into the US Great Lakes and wipe out other fish have led to rising demands that the government close the waterway connecting the lakes to the Mississippi River — an unprecedented step that could disrupt the movement of millions of tonnes of iron ore, coal, grain and other goods.

The dispute could become an epic clash of competing interests: commerce, environmentalists and fishermen.

Michigan Governor Jennifer Granholm and five environmental groups threatened on Wednesday to sue the US Army Corps of Engineers to force it to temporarily shut three shipping locks near Chicago because of evidence that Asian carp may have breached the electrical barrier that is supposed to hold them back from the lakes.

The environmental groups went further than the governor and said the Great Lakes and the Mississippi should be permanently separated to avert what Granholm called "ecological disaster".

Colonel Vincent Quarles, commander of the Corps' Chicago district, said the agency is considering all options but would not close the locks without first studying the possible effects.

Environmentalists fear that the fish, which consume up to 40 per cent 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 1.2 metres long and 45 kilogrammes 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.

Network

The Mississippi and the Great Lakes are connected by a complex, 402-kilometre 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.

The American Waterways Operators, a trade association representing the tug and barge industry, said closing the locks would lead to higher shipping costs because commodities would have to be sent overland via truck or train across Illinois before being put back onto vessels.

"The impact is going to be large," said Lynn Muench, the group's senior vice president for regional advocacy in St. Louis. "It could definitely impact day-to-day living."

Tens of millions of tonnes of goods are moved annually along the shipping canals or through the locks that lead into Lake Michigan. Muench had no estimate of the value of the cargo, which includes salt, sugar, molasses, cement, scrap metal and petroleum.

In the continuing struggle to keep the fish out, Illinois environmental officials planned to dump poison on Wednesday night in a stretch of the Chicago Sanitary and Ship Canal near Lockport to kill off the carp while the electrical barrier is turned off for maintenance.

Crews planned to use large cranes with nets to scoop up an estimated 90,700 kilogrammes of dead fish, which will 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.