Dennis Anderson: Asian carp invasion hits home; state fishery at risk

Four years ago the Minnesota Department of Natural Resources warned the Legislature and anyone else who would listen that silver carp -- the kind that can weigh more than 40 pounds and leap as high as 10 feet out of the water when they hear the whine of a boat motor -- would reach Minnesota via the Mississippi River unless a barrier were built to keep them out.

But no barrier was constructed, and the recent discovery that a silver carp was caught by a commercial fisherman near La Crosse, Wis. -- much farther north than its previously known location in Iowa waters -- indicates the DNR's warning should have been heeded.

At risk is a sport fishery in Minnesota and Wisconsin worth billions.

The silver carp is one species in a family of Asian carp that includes (among other species) bighead, grass and black carp -- each of them, essentially, evil. Each was imported, some by private aquaculturists; one, the grass carp, by government agencies looking for a fish to destroy unwanted vegetation.

Like all state agencies, the DNR makes occasional mistakes. But in this instance, it accurately described the threat that Asian carp represent to Minnesota's aquatic ecosystems, and warned as well the only hope Minnesota had to keep these fish out of its waters was to build an underwater, sound-emitting weir below one of the Mississippi's locks and dams.

Preferably that would have occurred in Iowa waters south of the Minnesota border -- preferably in the last two years. But the Army Corps of Engineers, which ultimately is the presiding authority over the river, has no money to act.

And until recently, the DNR hasn't had funds, either.

Because it's bonding money, the $500,000 must be spent within the state.

Already, silver carp are plentiful in southern portions of the Mississippi River and many of its tributaries. In Chicago, it is being kept out of Lake Michigan -- for now -- by an electric barrier (which has a lot of problems of its own). Asian carp also have been found in the Missouri River as far north as South Dakota.

Together with fast-reproducing and mussel-eating black carp, rapid-growing bigheads (which can weigh up to 100 pounds), and vegetation-chomping grass carp, silvers threaten not only fish such as walleyes, northern pike, muskies and bass, they undercut all forms of water recreation.

Especially, in the case of silver carp, water skiing, wakeboarding and boating.

Example: When startled by a boat motor, silver carp can leap into passing boats, colliding with, and injuring, passengers.

"The Corps has been given the authority by Congress to act, but hasn't been appropriated any money, so it says its hands are tied," Rendall said. "The DNR doesn't have the money to do it, at least not at this time. And I don't think Minnesota has the authority, anyway, in the Mississippi. We would have to act with the Corps and with Wisconsin."

Rendall said that widespread flooding in the Mississippi River watershed last spring probably aided the carp's movement upstream. The fish are capable of moving about 50 miles a year, and their next upstream shift likely will occur in spring. (Already bighead carp have been found in the St. Croix River and Lake Pepin, but in both cases these were believed to be rogue fish, not representative of a sizable migration northward.)

In the end, however, stopping the fish might be easier than coordinating a barrier's construction -- or even its approval. That's because the Mississippi is managed by the Corps primarily to facilitate shipping, and each lock and dam must play multiple and varied roles in that effort -- changing by season.

Stopping invasive species such as Asian carp likely will always be a secondary consideration.

"There's no silver bullet to get this done," Rendall said. "We're going to regroup with everyone. We have to talk to the Corps again, to Wisconsin, and with legislators, and see what we can do."

Footnote: As it continues to organize following passage of the constitutional amendment last month, the Lessard Outdoor Heritage Council will have to weigh the value of establishing an emergency fund held in reserve to address unforeseen threats of this kind to fish and wildlife.