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Great Lakes Article:

Volts may fend off invading carp
Tom Meersman and Mark Brunswick
Minneapolis Star Tribune
10/01/03


Minnesota natural resource officials said Tuesday that they are studying the possibility of building an underwater electric barrier across the Mississippi River to prevent the northward spread of Asian carp into the state's waterways.

The barrier, consisting of electrified cables or bars on the river bottom, would shock fish as they swim toward it. It might be installed somewhere between the Iowa border and the Twin Cities if a study concludes that it would work.

Two exotic species of carp, silver and bighead, have been expanding upriver since the 1980s, after they were imported by Arkansas fish farmers and apparently escaped.

The carp, which can weigh more than 60 pounds, are dangerous to boaters.

When motorboats pass through waters infested with silver carp, the fish routinely jump several feet out of the water and sometimes land in boats. The jumping fish have injured boaters and damaged their equipment.

Silver carp are moving up the Mississippi.Marlin LevisonStar Tribune"You get blood everywhere, slime everywhere and green poop, and that's if the fish doesn't fly to pieces," said Duane Chapman, fisheries biologist for the U.S. Geological Survey, who has been studying the carp for the past few years near Columbia, Mo.

Jay Rendall, exotic species coordinator for the Minnesota Department of Natural Resources (DNR), said bighead carp have been reported near the Minnesota border south of La Crosse, Wis., while the silver carp appear to be farther south in Iowa.

The carp, which are different from the common carp native to the river, feed on the same plankton consumed by native mussels, larval fish and even some full-grown fish, such as the paddlefish, he said. "Because of what they eat and how abundant they can get, they [Asian carp] are a significant threat to the whole food web of the river," Rendall said.

He said the DNR has hired Smith-Root Inc., a fisheries technology company in Vancouver, Wash., to look at stretches of the Mississippi -- mostly narrow sites including locks and dams -- where an electric barrier might be installed. The study will cost up to $5,000, he said.

Smith-Root built an experimental electric barrier in a canal that connects Lake Michigan to the Illinois River last year to prevent Asian carp from swimming up the canal and entering the Great Lakes. That $1.25 million barrier, located about 30 miles southwest of Chicago, consists of several spaced bundles of electric cables across the bottom of the 165-foot-wide canal. The system emits enough electricity to deter fish from swimming upstream.

The Asian carp are about 22 miles south of the electric barrier. It is being tested on several dozen common carp. Illinois officials, working with Smith-Root, the Army Corps of Engineers and others, are planning a $7.5 million permanent barrier nearby.

Ron Martin, aquatic invasive species coordinator for the Wisconsin Department of Natural Resources, said he is interested in a proposed barrier on the Mississippi. Authorities from several state and federal agencies and universities are scheduled to discuss the preliminary study results in late October. After that, the Minnesota DNR will decide whether the project is worth studying further.

If Wisconsin were asked to help pay for the barrier, that state's legislators would need assurances that the technology could stop the fish, Martin said. An electrified barrier also would affect native fish, which need to move up and down the river to spawn, he said.

Martin said he supports the study. "Any time you get 3-or 4-foot carp that are virtually eating machines, they're going to have an effect on the system," he said. "Instead of food that would be producing walleye, northern, bass or a number of other desirable species, all of a sudden that biomass is going into producing carp."

Vern Wagner, conservation director for the Minnesota B.A.S.S. Federation, said his group also hopes that the invasive carp can be blocked. "It is a subject of concern," he said. "They leap out of the water and attack people in their boats. None of us wants to have that happen to us."

However, Wagner said it might be difficult to construct barriers or gates on the Mississippi.

Pam Thiel, project leader for the U.S. Fish and Wildlife Service in La Crosse, said locks and dams have slowed, but not stopped, the movement of silver and bighead carp. She said the experimental barrier near Chicago is on a canal that is only about the width of two barges. A similar structure on the Mississippi probably would need to be much larger and far more expensive, she added.

"We need to look at the feasibility of this first and then make a more educated decision," she said. "But these carp have infected our riverways, and so it's going to be difficult to find a magic potion or some physical solution to eliminate them or even slow them down."

Scott Elkins, state director of the Sierra Club, said constructing barriers "is kind of like putting your thumb in a dike once the dam is crumbling." Money would be better spent to educate people about exotic species and to prevent others from being introduced, he said.

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