Voracious Asian carp poised to upset Great Lakes
Written by Chicago Tribune   
Saturday, 28 November 2009 07:46
Conservationists and government biologists, stunned by new indications of the advance of Asian carp toward Lake Michigan, are trading ideas for poisoning Chicago-area rivers, conducting emergency electrofishing or chemically neutering the wily fish.

On Friday, sophisticated genetic testing near Chicago found evidence of the carp within 7 miles of Lake Michigan after apparently leaping an electrical barrier once called the last line of defense for the Great Lakes.

The prospect of the voracious, prolific Asian carp reaching the Great Lakes -- a fragile ecosystem reeling from other invasive species -- has been the greatest fear of the lakes coalition.

Tests for Asian carp DNA have been conducted since August. The findings, available only in recent days, indicate that the pernicious plankton eaters are only one lock and dam away from the Great Lakes, said Army Corps of Engineers Maj. Gen. John W. Peabody, commander of the corps' Great Lakes and Ohio River Division.

The discovery has spurred a crash effort to find fish to confirm the tests, but experts said false readings were unlikely. "There is no reason to think that there aren't carp present when the DNA is detected," said David Lodge, a researcher with the University of Notre Dame who is conducting the genetic analysis. "It's hard to come to any other conclusion other than that there are carp somewhere in the region."

The tests sift carp DNA out of suspended particles floating in river currents, and they indicate for the first time that bighead and silver carp are just below the O'Brien lock on the Calumet River, in the Des Plaines River above the Lockport lock and at the confluence of the Calumet Sag Channel and Chicago Sanitary and Ship Canal. All three locations are above the multimillion-dollar electrified carp barrier built to keep invasive species from moving from the Illinois River to the Great Lakes, and vice versa.

Because Asian carp show a powerful aversion to electricity, electric cables were strung across the bottom of the Sanitary & Ship Canal to form a temporary barrier in 2002. The Corps of Engineers reinforced it in 2004 with a permanent and more powerful barrier nearby, while Illinois Environmental Protection Agency ecologists kept a wary eye on the invasive carp as they surged north up the Illinois River.

Three years ago, the Asian carp were no closer to Chicago than Joliet -- and seemed to be holding there.

Friday's announcement hit Great Lakes groups like a crashing wave.

A stretch of the Sanitary and Ship Canal will be sterilized with the poison Rotenone in December.

Among the possibilities under study is trying to sterilize male Asian carp, a years-long, intensive effort that would be similar to ridding the Great Lakes of sea lampreys, said Charles Wooley, U.S. Fish and Wildlife Service Midwest deputy regional director. Another includes targeted poisoning of stretches of the rivers where Asian carp can be confirmed.

In the meantime, netting and electrofishing -- electrifying the water to stun fish and then net them -- will start where carp genetic material was found, said John Rogner, Illinois Environmental Protection Agency assistant director.
 
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