By Rona Kobell
July 24, 2002
Scientists at the Paul S. Sarbanes Cooperative Oxford Laboratory began yesterday testing several different doses of the fish poison rotenone on the 80 torpedo-shaped, silver fingerlings that have taken up residence in eight tanks filled with murky pond water.
State fisheries experts want to see whether - and how quickly - the invasive natives of China will perish, signaling to worried biologists that Crofton's infestation can be destroyed before the exotic fish devour native species or escape to disrupt local ecosystems.
Meanwhile, U.S. Interior Secretary Gale A. Norton made her own move to contain the fish, proposing a federal ban on importing all 28 snakehead species. Federal authorities estimate nearly 17,000 snakeheads have been imported nationwide from 1997 to 2000, most of them sold in live fish markets or the aquarium trade. The fish are illegal in 13 states but can be imported legally in Maryland. (Releasing a nonindigenous species into the wild is illegal here.)
"These fish are like something out of a bad horror movie," Norton said of the creatures, which can breathe air, survive on land for three days and slither along on their fins. "We simply must do everything we can to prevent them from entering our waters, either accidentally or intentionally."
The snakehead surfaced in Maryland this summer when an angler caught a strange, toothy fish, later identified as a northern snakehead, in a pond behind the Dunkin' Donuts on Route 3. A local man acknowledged that he'd placed two adult fish - a male and a female - in the pond two years ago when they outgrew his aquarium. Biologists have caught about 100 juvenile snakeheads - the survivors of which are in Room 41. The scientists fear hundreds more are lurking in the pond.
Last week, a panel of fisheries experts decided that the fish had to be killed before reaching the nearby Little Patuxent River and picked rotenone as the best poison.
The plant-based poison kills the fish by disrupting the flow of oxygen to the gills. Though it hasn't been used to eradicate fish in Maryland in decades, fisheries managers in Florida use it frequently to control exotic predators. It also is used as an insecticide in gardens. It is odorless and doesn't harm humans or other wildlife that might eat rotenone-infected fish, biologists say.
If rotenone works in the Oxford laboratory and the Department of Natural Resources secretary agrees to use it after getting a recommendation next week, officials could be dumping the liquid poison into the pond as early as next month.
"It's the obvious choice, and we've got to determine which doses will work," said Andrew Lazur, an aquaculture specialist with the University of Maryland Center for Environmental Science's Horn Point Laboratory who is conducting the experiments. "What we don't know is what this animal can tolerate."
To assess the poison's effects, Lazur and John Jacobs, another researcher from Horn Point, have divided the fish into eight tanks, 10 fish in each one. Two of the tanks will be the control group and will not get rotenone. Two tanks will get a low dose, two a medium dose and two a higher dose.
They've also outfitted one tank with a "snakehead beach" - a rectangular piece of plastic foam that the snakehead could walk onto if it tried to escape the poison - to determine how long it survives outside water.
Lazur, who also sits on Maryland's snakehead panel, said he will run the experiment for 96 hours and expects to release the results by early next week. He doesn't know how long it will take for the rotenone to work but says that a different snakehead species died within 24 hours when exposed to high doses of rotenone in a Bangladesh experiment.
Until yesterday, the snakeheads lived well in Room 41. They fed on dried krill and swished their tails back and forth in water imported from the Crofton pond. Except for yesterday, when news cameras came in two by two so as not to put stress on them, the fish had few disruptions.
And their lodging is free. The lab - a joint venture between the Department of Natural Resources and the National Ocean Service, part of the National Oceanic and Atmospheric Administration - is providing the space and the scientists.
"We were able to do the testing more or less on the spot, so it was an obvious place to do it," said Stephen Jordan, the lab's director. "From my perspective, anyway, there's no cash going into this work - and that's the way we like to do things."
Department of Natural Resources officials have resisted putting a dollar figure on the snakehead problem. Yesterday, they welcomed Norton's announcement, greeting it with hope that no other state will have to pay the price - fiscally or environmentally - for harboring a snakehead.
"It's an important step in helping to prevent this problem in Maryland from occurring somewhere else," said department spokesman John Surrick.
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