Invasive "Walking" Fish Not Wreaking Havoc Yet, Scientists Say

Brian Handwerk
for National Geographic News
October 3, 2006

The infamous snakehead, once dubbed the "Frankenfish," is in the U.S. to stay, experts say. Fortunately, the Asian import seems to be coexisting peacefully with native species—for now.

The Potomac River, which runs through West Virginia, Virginia, Maryland, and Washington, D.C., on its way to the Atlantic, has seen a thriving population of snakeheads arise after several of the fish were released into Virginia's Dogue Creek in Fairfax County (map of Virginia).

But so far the snakeheads appear to have had little discernable impact on the native ecosystem, to the relief of scientists and anglers alike.

"We have not seen any adverse effects," said fisheries biologist Steve Owens, with Virginia's Department of Game and Inland Fisheries in Fredericksburg.

But surveys also show that northern snakehead populations are booming in the Potomac.

The aggressive predators are appearing in more locations and in far greater densities than they did just last year.

Snakeheads now occupy at least 15 miles (24 kilometers) of the Potomac River and its tributaries.

The fish frequent large swaths of weedy shallows—making eradication efforts almost impossible. (Related: "Maryland Wages War on Invasive Walking Fish" [July 2002].)

Steve Minkkinen coordinates the U.S. Fish and Wildlife Service's snakehead control and management plan from Annapolis, Maryland.

"In places where they've had an introduction and they've established a beachhead, like snakeheads in the Potomac, we don't have any track record for being able to eradicate aquatic species like that," he said.

Worrying for Nothing?

Alien species can wreak havoc in ecosystems that evolved without them by outcompeting—or outright eating—native inhabitants.

Continued on Next Page >>


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