Published November 29, 2009, 12:00 AM

Carp battle headed our way

Asian carp are feared to have breached a Chicago barrier, and fisheries experts worry that the huge, ugly invasive fish will now wreak havoc in the Great Lakes.

By: John Myers, Duluth News Tribune

The Great Lakes have never seen anything quite like them: carp from Asia that grow to more than

100 pounds, outmuscle native fish and have the ability to filter half their weight in food out of the ecosystem every day.

“I had hoped we never would see them. But now, it’s not looking good,’’ said Don Schreiner, Lake Superior Area Fisheries supervisor for the Minnesota Department of Natural Resources.

While Asian carp may seem like just the latest in a never-ending string of exotic species poised to invade the Great Lakes, they would certainly be the most obvious: A fat fish known to leap eight feet into the air when disturbed by passing boats or Jetskis.

Asian carp aren’t newcomers to North America. They’ve wreaked havoc for 20 years on parts of the Mississippi River, and the News Tribune first reported on the threat they’ve posed to the Great Lakes in 2002.

But it wasn’t until Nov. 20 that biologists confirmed Asian carp DNA in the water on the wrong side of an electrical barrier on the Illinois River system intended to keep the fish out of Lake Michigan. While no Asian carp has been found above the barrier yet, scientists say there’s no other explanation for the DNA in the water.

State and federal agencies sprang into action with an elaborate plan to poison the canals and river, killing all kinds of fish.

On Wednesday, the Asian Carp Rapid Response Workgroup — including the U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, Illinois Department of Natural Resources and the U.S. Coast Guard — will begin work to keep the carp out of Lake Michigan.

If the effort is too little, too late, it’s not clear what impact the Asian carp will have if they hit the Great Lakes.

“Even if they are already in the lakes, there may not be the kind of spawning habitat they need to really flourish, to reproduce,’’ Schreiner said. “Then again, just having them here could wreak havoc.’’

Lake Superior may be too infertile for a fish that needs to eat so much. Yet Asian carp could possibly thrive in the warmer, darker, very fertile waters of the Twin Ports harbor, the St. Louis River estuary that already teems with native fish and foreign invaders.

“The river is a different story. That may be just the kind of habitat they need,’’ Schreiner said.

Asian carp feed by filtering tiny organisms out of the water as they swim near the surface. Two versions, the bighead carp and silver carp, lack true stomachs, so they must feed almost continually to stay alive. They won’t directly compete with walleyes or lake trout, but they would eat the same food that tiny baitfish eat.

“They’d be going after the base of the food chain,’’ Schreiner noted. Dennis Pratt, area fisheries manager for the Wisconsin DNR in Superior, said the fish may not need years to swim from southern Lake Michigan to western Lake Superior.

“They might just hitchhike here,’’ he said, citing other species that have migrated to the area in the ballast water of lake-faring vessels. There’s nearly constant movement of lakers between southern Lake Michigan and the Twin Ports.

Minnesota and Wisconsin already have Asian carp in their waters of the Mississippi River system, although it’s unclear how far up the river they have colonized. They have been caught by anglers as far north as the St. Croix River. And even if they don’t move into Lake Superior, Asian carp could colonize much of the two states via other routes.

If they do make it here, Chris Brackett, an Illinois outdoor videographer and bow-fishing guide who has been shooting the leaping fish for years, said they may not be as bad as feared, possibly ending up as food for native fish.

“I think they’ve been in Lake Michigan for two years already and [scientists] just don’t know it yet,’’ Bracket said. “There are so many of these little carp fry swimming around [in the Illinois River] that the bass and other species are doing great feeding on them.’’

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