Bighead carp snagged in St. Croix River

That's why the arrival of a 27-pound bighead carp in the St. Croix River on Monday triggered alarm among officials at the state Department of Natural Resources, who fear the invasive species could damage Minnesota's aquatic ecosystems and threaten its treasured walleyes and sunnies.

Naturalists said the lunker probably swam upstream from Iowa, and that there's no sign the carp are reproducing in Minnesota waters.

Nonetheless, its arrival couldn't have occurred at a more politically opportune time. Democratic Gov. Mark Dayton has proposed $16 million in state bonding funds to rebuild the Coon Rapids dam as a barrier to stop the carp from spreading to the state's prime fishing lakes north of the Twin Cities. State officials are also pressing federal authorities to close, at least temporarily, one of the lock-and-dams between Red Wing and Minneapolis to create a barrier further downstream.

"This is not a crisis," said Luke Skinner, the DNRs invasive species supervisor. Asian carp have been found in Minnesota seven times since 1996, most recently in January, 2009. "But they are knocking on our door," he said.

National attention has focused on fears of the Asian Carp's imminent arrival in Lake Michigan and the Great Lakes via the Illinois River near Chicago.

But a news conference held Wednesday in St. Paul reflected DNR officials' fears and frustrations. "Much of the focus is on Chicago and the Great Lakes," Skinner said. "We need to divert that attention to Minnesota."

The 34-inch bighead displayed in a trough of bloody ice at the DNR headquarters Wednesday was certainly eye-catching enough.

It was caught Monday by a commercial fisherman in the St. Croix River near the Highway 10 bridge at Prescott. DNR fish biologist Brad Parsons said it was a "flyer," a fully mature, healthy bighead that had most likely swum up from Iowa on the high, spring flow of the Mississippi. This time of the year, locks and dams are wide open to allow the volume of water in the river to flow south.

The bighead is one of four species of Asian carp that are invasive to American rivers. It is not the dreaded leaping carp that can knock people out of their boats - that's the silver. But it can grow to 110 pounds and cause havoc for native fish.

Asian carp were imported from China in the 1970s to control plankton in aquaculture ponds. By the early 1980s, both the bighead and the silver carp had escaped into open waters in the South.

All of them can do massive ecological damage. Parsons said that bighead eat 40 percent of their body weight every day in plankton and bugs.

"They really upset the food chain," he said, and replace other game fish in their ecosystems.

In the Missouri River, where they are well established, they now make up 90 percent of the fish population, he said. Last week, a carp-removal project in Iowa pulled 43 tons of invasive fish from a 17-mile stretch of the Mississippi in four days.

At this point the closest reproducing population is in Iowa, Sinker said.

The only thing that will stop them is a natural or man-made barrier. Taylor Falls east of the Twin Cities, for example, will likely stop their spread up the St. Croix, Sinker said. St. Anthony Falls would have stopped them in their tracks in Minneapolis - except for the lock and dam that was installed there decades ago to facilitate shipping.

In Chicago, an electric barrier was set up to prevent them from finding their way to Lake Michigan through a shipping canal, and a lawsuit is pending on whether to permanently close the canal.

On the Mississippi there are only two options. One is to close one of the lock and dams, which would require federal approval. Sinker said those discussions are under way, though the Army Corps of Engineers has said it would agree only on an act of Congress.

The other option, which is within the state's power, is a plan to rebuild the Coon Rapids dam. That would essentially mean sacrificing the lower length of the Mississippi, including Lake Pepin, and the Minnesota River to carp invaders. But it could preserve the state's $4 billion fishing industry up north.

But that's controversial as well. It would require $16 million, and, according to some, it would only work for 10 or 15 years and might not be sufficient at times of high water.

Paul Labovitz, superintendent of the 72-mile Mississippi National River and Recreation Area, says it would be more effective to simply close the locks at Lock and Dam No. 1, a massive structure below the Ford bridge between Minneapolis and St. Paul, or the Upper St. Anthony Lock and Dam, a 49-foot drop near downtown Minneapolis' Stone Arch Bridge.

Whatever the state does, Sinker said, it has to happen fast.

"We need action," he said. "Soon."

(c) 2011, Star Tribune (Minneapolis)
Distributed by McClatchy-Tribune Information Services.