Maryland Suffers Setback in War on Invasive Walking Fish

Hillary Mayell
for National Geographic News
July 12, 2002

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The news keeps getting worse for Maryland wildlife officials. Biologists sampling the lake captured more than 100 juvenile northern snakeheads, confirming their worst fears: The air-breathing, land-crawling, voracious predator found in a pond in Crofton, Maryland, is multiplying.

Finding that many doesn't provide scientists with enough information to estimate the overall number of northern snakeheads now living in the pond.

"You only expect to get a small percentage of the fish when you're sampling," said Steve Early, Maryland's freshwater fisheries manager, who conducted the survey. "But I'm worried if I have 100 or if I have 1,000 in the pond; I've still got too many."

Finding the juveniles means the northern snakehead is now an established population in the Crofton pond, said Walter Courtenay, professor emeritus of zoology at Florida Atlantic University. "All it takes is the ability to successfully reproduce to be defined as an established population," he said.

Courtenay, who has been preparing a risk assessment on the snakehead for the U.S. Geological Survey since September, estimates that the juveniles are about five months old.

State fisheries managers were first alerted to the possibility of an invasion by an alien species when an angler caught, photographed, and threw back an unusual looking fish in mid-May.

Plans to rid the pond of the fish were put into motion as soon as it was identified as a northern snakehead.

The proximity of the Little Patuxent River and the fish's ability to breathe out of water and travel across land has increased the sense of urgency among wildlife officials.

A scientific panel of federal and state officials representing a number of disciplines will be convened, perhaps as early as next week.

"The panel will be looking at a number of strategies for containment and control of this population, as well as long-term recommendations on how to better prevent similar invasions," Early said.

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