Scientists favor dividing Great Lakes, Mississippi to halt Asian carp

No additional study is necessary to prove that separating the Great Lakes and the Mississippi River systems is the only way to prevent invasive species such as Asian carp from migrating between them and doing serious ecological and economic harm, a team of scientists said Thursday.

In a newly released paper, the scientists said opponents of severing the man-made link between the two watersheds were spreading myths, including that electric barriers are enough to stop the unwanted carp from entering Lake Michigan through a Chicago-area shipping canal.

Opponents also have claimed falsely that it's too late to keep the carp out of the lakes, or they can't survive in the lakes because of inadequate food and spawning habitat, or even if they do spread in the lakes they won't do much damage, the scientists said.

Their article in the Journal of Great Lakes Research urges Congress to approve legislation ordering the Army Corps of Engineers to quicken a study of whether to divide the two freshwater basins, now due for completion in 2015.

"The task at hand needs to be not if, but how to solve the problem," said Jerry Rasmussen, a consultant and retired U.S. Fish and Wildlife Service invasive species expert.

Other authors of the paper included Richard Sparks of the National Great Rivers Research and Education Center in Godfrey, Ill.; William Taylor, a Michigan State University fisheries specialist; and Henry Regier, a Great Lakes scientist at the University of Toronto.

Mark Biel, chairman of a business and industry coalition called UnLock Our Jobs that the scientists singled out for criticism, said their article was biased.

"The issues this report claims to address have been asked and answered repeatedly," Biel said. "It's time we move on to maintaining and improving current barriers as well as implementing comprehensive solutions across the region. Separation simply isn't one of them."

His group contends that dividing the basins or closing shipping locks would cost billions and devastate a regional economy that depends on movement of cargo on northern Illinois waterways.

Asian carp are voracious filter feeders that can reach 4 feet long and 100 pounds. Imported decades ago to gobble algae from Deep South fish farms and sewage treatment plants, they escaped into the Mississippi and have moved northward since. An electric barrier network on the Chicago Sanitary and Ship Canal about 25 miles from Lake Michigan is designed to bock their path.

State and federal agencies are using other methods to keep Asian carp out of the lakes, including stepped-up commercial fishing.

"The Asian carp are going to whack the tributaries. They will change the food web and dominate our streams."

Rasmussen and his colleagues conducted no independent research for their paper but drew on reports by other scientists, including University of Notre Dame specialists who have reported detecting Asian carp DNA beyond the electric barrier.

The paper said the barrier, while helpful, isn't strong enough to kill fish and cannot prevent downstream movement of fish eggs, larvae, invertebrates, parasites and bacteria. Studies also show that Asian carp would find abundant food in the Great Lakes, including the nuisance algae cladophora, and can survive throughout the region, they said.

"The Asian carp are going to whack the tributaries," Taylor said. "They will change the food web and dominate our streams and nearshore regions in the Great Lakes basin."

While attention has focused on Asian carp's threat to the lakes, the Mississippi basin may be even more vulnerable to species moving southward, the paper said. The ecologically diverse river's 260 fish species could be crowded out by newcomers from the Great Lakes such as the round goby, it said.

Placing a physical barrier between the two basins is the surest method of protecting them, Rasmussen said. But because it would be costly and take years to build, authorities should consider buying time with short-term measures such as creating hot-water pools or reducing oxygen levels in sections of the Chicago waterways to kill migrating organisms, he said.

"The longer you wait, the more species cross," Sparks said.

(Copyright 2011 by The Associated Press. All Rights Reserved.)

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