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Snakeheads Go Beyond the Pond
When the first of the northern snakeheads, the Asian exotic fish that
can breathe air and survive for short periods on land, was plucked from
a Crofton, Maryland pond in the summer of 2002, it catapulted onto
David Letterman's Top Ten list and grabbed the nation's collective
conscious. Now the infamous fish is back in the Chesapeake region and
it could be settling in to stay.
Troubles began again on April 26, when an angler snared a 19-inch,
female snakehead from a pond in Wheaton, MD. Over the next week, the
Maryland Department of Natural Resources (DNR) drained the pond but did
not find other fish.
The resource managers' sigh of relief was short-lived, however, and the
following weeks have brought further cause for concern. On May 7, a
fisherman landed an immature female snakehead from Little Hunting
Creek, a tributary of the Potomac River in Virginia. Later in the week,
another angler pulled up another female on the nearby Maryland side of
the Potomac, in Charles County. And a few days after that, a
participant in a bass fishing competition snagged a third snakehead, of
a similar size, from a site along the Potomac about 10 miles downstream
from Little Hunting Creek. Maryland DNR has posted emergency snakehead
fish warning signs along the Potomac. The agency is encouraging
fisherman who catch them to kill them and to expeditiously report
findings to the authorities.
Unlike ponds, which are contained bodies of water that can be drained
and the fish removed, the Potomac River is a system of interconnected
waterways that stretches for 280 miles. "From a management standpoint,
finding the fish in an open body of water certainly elevates the level
of concern," says Andy Lazur, an aquaculture extension specialist from
Maryland Sea Grant Program, who served on the Maryland Snakehead
Scientific Advisory Panel in 2002. "And if the fish does become
established, managers will have to manage around the fish. And there
are limited tools available," he says.
But finding a few snakeheads in the Potomac does not mean that a
reproducing population has established. "Three fish, a population does
not make," cautions Paul Shafland, director of the Non-Native Fish
Research Laboratories of the Florida Fish and Wildlife Conservation
Commission in Boca Raton, FL. "Three fish out of the same and adjacent
systems does certainly raise your eyebrows, but it is important to
confirm the existence of a population before jumping to any
conclusions," he says.
Some believe that the evidence is already fairly compelling,
however. "Snakeheads are probably already pretty widespread in the
system," says fisheries biologist and snakehead specialist Walter
Courtenay from U.S. Geological Survey's Florida Integrated Science
Center in Gainesville. The larger fish caught in Wheaton is of a
different size and age class than the three caught in the Potomac, and
these bodies of water can all be linked together geographically which
suggests that there might be a reproducing population, he says.
But even if the snakehead is here to stay, the effect of a new predator
in the food web will take years to understand and, in the end, may not
have a catastrophic ecological impact. "Freshwater fish communities are
far more plastic and resilient than we would expect," says Shafland.
"An introduction of a freshwater exotic is more akin to ecovandalism
than ecoterrorism," he says. In addition, other predators in the
system, such as large-mouthed bass may actually consume snakeheads.
According to Lazur, "There is no way to predict how these fish will
respond as both predator and prey in the system. It remains to be
seen."
Whether or not snakeheads live up to their "Frankenfish" profile in the
media, they have become poster children for communicating the risks of
introducing exotic species to the environment. "If there is one take
home message from the snakehead introduction," says Shafland, "it is
that it is the public's responsibility not release exotic species into
the wild. It is illegal and it is inhumane for the animal. We need to
take this seriously," he says.
- Erica Goldman
Northern Snakehead Weblinks
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