Sun, Oct 08, 2006 - Page 7 News List

US ecosystem threatened by invasive fish species


Dick White of Havana, Illinois, is a commercial fisherman on the Illinois River, and in recent years he had grappled with a problem shared by fishermen and wildlife officials throughout the country: invasive fish species disrupting ecosystems in US waterways.

Asian carp have infested the rivers flowing into the Mississippi to such an extent that White said he could no longer leave his nets in the river overnight, and the numerous carp leaping near passing boats have become a threat to passengers. White said being hit by fish was a normal occupational hazard now.

"We certainly can't take our kids or grandkids out on the river," he said in a telephone interview.

Unwanted foreign species like northern snakeheads, Chinese mitten crabs and tilapia have found their way into rivers and coastal waters, a consequence of increased recreational and commercial boat travel, a booming aquaculture industry and growing immigrant populations whose practices may clash with wild resource management.

White is experiencing firsthand the damage done by two Asian fish species, the silver carp and the bighead carp, which have increased in numbers so dramatically in the waters making up the Mississippi flowage that they are the most numerous large fish present.

Asian carp have displaced and deteriorated the stock of the average five-pound buffalo carp that White has caught and sold for most of his 30 years of fishing on the Illinois River.

"There are millions of them," he said. "They tear up my nets, which are not designed to handle such large fish."

Bow fishermen on the Illinois River and other Mississippi tributaries have made a sport of trying to shoot the fish in the air. In a new competition on the Illinois River called the Redneck Rodeo, participants in boats try to collect the most leaping carp. Dick White said the last event drew 80 boats and a crowd of 1,800 people.

John Chick is not among those finding enjoyment in the proliferation of invasive species. As director of the Great Rivers Field Station for the Illinois Natural History Survey in Alton, he has a view of the issue from his perch on the Mississippi.

The survey is collaborating with the US Army Corps of Engineers and the US Geological Survey to find solutions before carp infestations become an ecological disaster.

"Everything we see says that these populations have done nothing but increase," he said in a telephone interview.

In August, schools of tilapia began showing up in the Monongahela River, to the delight of anglers and the consternation of the Pennsylvania Fish and Boat Commission, which tried unsuccessfully to net and destroy them. How tilapia wound up in the Monongahela is a mystery, although a local fish market sells them, and federal wildlife officials say the live release of exotic species -- in religious rituals or by immigrants wanting to establish familiar food sources -- is a growing problem.

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