Snakeheads Colonize States

The 300 snakeheads caught in a Potomac River tributary last month were more than an anomaly. They were proof, biologists say, that the predatory Asian fish has bred its way to the top of the river's food chain.

The snakeheads caught in just a few days numbered more than four times the total ever found in the river -- evidence that not only are they thriving, but they also appear to be breeding faster than the river's most beloved game fish.

"I caught 62 in two hours, they were that thick," said John Odenkirk, a Virginia Department of Game and Inland Fisheries biologist. Worse, he said, "there's not a lot we can do."

Having lost the battle to eradicate the snakehead, Virginia and Maryland biologists and federal wildlife officials have recruited a team of researchers to study its adaptation. They hope that the fish will find a place in the Potomac's ecosystem without damaging the other species there.

What they know so far is this: The freshwater northern snakehead was probably introduced into the Potomac about three years ago, perhaps by someone who imported it from Asia, where it is a popular food.

With a mouth as big around as a fist and lined with rows of teeth and an ability to grow to three feet over an estimated life span of a decade, the adult fish has no known predators in the Potomac.

Their apparent quick adaptation shows the northern snakehead . .

". . would have the ability to colonize a large portion of the U.S. and even southern Canada," so says Steve Minkkinen, a snakehead expert at the U.S. Fish and Wildlife Service.

In 2002, this region's first snakeheads were found in a fetid pond in Crofton. Wildlife experts poisoned the pond and counted the fish. Six adults and more than 1,000 juveniles were proof that the fish bred successfully even in the pond's poor habitat. Already, they outnumbered the bass there.

In May 2004, an angler caught the Potomac system's first snakehead, in Little Hunting Creek near Alexandria. Biologists and anglers caught 20 snakeheads in 2004. This year, they've caught more than 300, 270 during the week-long run at Dogue Creek. DNA tests showed that the juveniles among the 20 fish caught in the Potomac in 2004 were all descended from one or a few related females, making it possible that the Potomac's snakehead problem originated with the introduction of only a few fish.

"It grows fast, bites anything that comes by, fights hard and taste great," with firm, white flesh similar to perch, Odenkirk said.

And that's a bad thing, because when anglers grow fond of a fish they introduce it elsewhere. That is how the walleye, a Midwestern game fish, invaded the Columbia River.

From The Washington Post, November 5, 2005.