Toxin Works on Snakeheads

Md. Looks for Way to Clear Crofton Pond of Invader Fish

Their attributes may have given them a mythical aura -- air-breathing, slithering, omnivorous creatures that can quickly clear a pond of flora and fauna.

But the northern snakeheads captured in a suburban Maryland pond this month have met their match in a common fish poison called rotenone.

Within 24 hours, all 48 of the baby snakeheads that had been administered the toxin by state biologists had succumbed, according to Maryland officials.

"Those who got a dose of poison have given themselves to science," said a state scientist who commented on condition of anonymity. "We speak of them in the past tense now."

The tests indicate that state officials have acquired the key to vanquishing the voracious Chinese snakeheads, which have captivated the public and spawned a backlash against the invasive species at the highest levels of U.S. government.

On Tuesday, even as U.S. Interior Secretary Gale A. Norton was declaring snakehead fish "something from a bad horror movie" and was proposing a ban on its importation, scientists at the Paul S. Sarbanes Oxford Cooperative Lab in Oxford, Md., began a 96-hour experiment designed to determine the effectiveness of the poison on juvenile snakeheads.

Sixty-four baby fish caught this month in a Crofton pond were divided among eight tanks in the cramped, dank lab and in the early afternoon the experiment began. Scientists administered poison to all but two of the tanks.

Within minutes, poisoned fish started to show signs of distress, darting and diving in the water and racing to the surface to gulp air.

Within an hour, they started to succumb. Within 24 hours, scientists were ready to write up their reports. No three-day vigil was needed. The recommended doses listed on the label did the job.

"I asked, 'Did it work and work at all concentrations?' " said Don Boesch, president of the University of Maryland Center for Environmental Sciences, which provided the two scientists who did the experiment. "The answer was, 'Yep.' "

Yesterday, scientists began writing up the results of the experiment, which will be included in a report to the state natural resources secretary from Boesch on how to handle the problem. Officials have not determined a price tag or a date for poisoning the Crofton pond.

"Sooner rather than later" will be the guiding principle of a panel of experts convened on the matter, Boesch said.

Once the poison is dumped, it should dissipate within four days, officials say. The pond could later be restocked with native species after a cleanup of the rotting fish and weeds there.

The experiment offered "no surprises," one scientist said, "but it needed to be done to assure the fact that if you dump rotenone in the pond, the [snakehead] will bite the bullet."

"Indeed," Boesch said, "it is effective."