Expert: High risk of Asian carp invading lakes

Signs of Asian carp in Chicago waterways mean there's a great risk the invasive fish could slip into Lake Michigan at any time, a witness said Tuesday in the first full day of testimony in a five-state lawsuit.

Michigan, Wisconsin, Ohio, Minnesota and Pennsylvania want a federal judge to close two shipping locks and install barriers to prevent the ravenous fish from overrunning the Great Lakes and potentially devastating its $7 billion-a-year fishing industry.

"I think there is a risk, a very imminent risk of invasion," biologist David Lodge testified for the states. He added ominously that such "invasions are often irreversible."

The city of Chicago, the regional barge industry and others object to closing the locks, arguing the move would undermine critical flood-control measures and hurt businesses who rely heavily on the waterways.

The defense questioned the warning of looming disaster, pointing out the limits of what's known about Asian carp, including whether they would reproduce well or find the right kind of food in the Great Lakes.

"Scientists disagree about the establishment of Asian carp in Lake Michigan," the lead defense attorney Maureen Rudolph said Tuesday during cross examination.

Testimony was scheduled to continue Wednesday.

One focus Tuesday was the reliability of genetic testing that Lodge, a University of Notre Dame scientist, said showed Asian carp in the Chicago area.

Those opposed to closing the locks have cast doubt on the so-called environmental DNA tests, which look, not for the fish itself, but for traces of Asian carp DNA.

Some suggest the carp DNA found near Lake Michigan could have been transported in barges' ballast water and bird droppings. If it was, they argue, that could mean the fish themselves aren't necessarily present.

But Lodge insisted that by far the most plausible explanation for the DNA is that it came from discarded cells of carp living in the waterway. DNA can degrade within hours, he said, so it probably wouldn't have survived transport in a barge or a bird.

Under cross examination by Rudolph, Lodge conceded the DNA tests can't determine whether there is just one carp in an area or hundreds.

Asian carp, which can weigh up to 100 pounds, have been migrating up the Mississippi and Illinois rivers toward the Great Lakes for decades. Biologists fear if they fish get into the lakes, they would gobble plankton and starve out prized species such as salmon and walleye.

The lawsuit, filed in U.S. District Court in northern Illinois, accuses the U.S. Army Corps of Engineers and the Metropolitan Water Reclamation District of Greater Chicago of creating a public nuisance by operating locks, gates and other infrastructure through which the carp could enter the lakes.

The five states want to temporarily close the O'Brien and Chicago locks and install barriers to stop the fish. The states' request makes allowances for water releases to prevent flooding and other threats to public safety.

The U.S. Supreme Court has twice rejected state pleas to close the locks, but did not rule on the merits of the legal claims.

On the first day of hearings last month, Michigan assistant attorney general Robert Reichel argued that the threat to the Great Lakes has reached a "biological tipping point" and the waterways leading into Lake Michigan have become "a carp highway."

Rudolph, a U.S. Department of Justice attorney, said Congress has given the Corps discretion in how to deal with the problem and the court should be reluctant to get involved.

(Copyright 2010 by The Associated Press. All Rights Reserved.)