- The Washington Times - Wednesday, September 18, 2002

The poison used to kill off northern snakehead fish in a Crofton pond has lingered longer than expected, prompting Maryland wildlife officials yesterday to add a neutralizing agent to the pond.

State biologists feared a storm might wash the fish poison rotenone out of the pond and into the nearby Little Patuxent River, where it could kill native fish. To neutralize the poison and prevent it from spreading, they applied potassium permanganate to the pond yesterday morning.

Wildlife officials planned to test the pond today to determine if the rotenone had dissipated.

"Our concern was that a storm could wash over the rotenone and the toxicity into the Little Patuxent River and cause harm to the fishery," Department of Natural Resources spokeswoman Heather Lynch said.

"Obviously, it is a piscicide. It kills fish," she said. "And its enormous efficacy is demonstrated by its success here" in killing more than 1,000 snakeheads in the pond.

Wildlife officials originally predicted the rotenone would decompose quickly with warm water temperatures. The poison lasted because recent rain and cloud cover kept the temperature low and slowed the rotenone's decomposition, according to a DNR statement issued yesterday.

Wildlife officials wanted to kill off the snakeheads, a fanged fish from China that can breathe air and crawl across the ground on its fins, because the predatory fish threatened to devour native species and could introduce foreign disease or parasites if it migrated to the Little Patuxent River.

They have found no evidence that either the snakehead fish or the poison had migrated from the pond, Ms. Lynch said.

The rotenone applied to the five-acre pond and two smaller adjacent ponds on Sept. 4 eradicated the snakeheads in a matter of weeks. Wildlife officials removed six dead adult snakeheads and about 1,000 dead baby snakeheads from the pond.

The adults measured as long as 27 inches, and the babies ranged in size from 1¼ to 5 inches.

Despite the success in poisoning the Crofton snakeheads, Ms. Lynch said there was no guarantee against another snakehead infestation in the pond or in another Maryland waterway.

The snakeheads thrived and multiplied in the Crofton pond after a resident dumped two of the fish in the pond two years ago. After an angler caught a snakehead this summer, which touched off snakehead mania in Maryland, the man who dumped the fish told DNR police what he had done. He said he bought the aquatic oddities in a New York fish market and disposed of them when they grew too large for his aquarium.

"We hope that out of all of this the public has been educated enough about the northern snakehead to know that it can cause enormous harm," Ms. Lynch said.

The department is expected to endorse proposed laws to prohibit the introduction of the snakehead species in Maryland. Earlier this month, a panel of scientists studying the snakehead infestation in Crofton recommended tough laws to prevent a repeat of this summer's "frankenfish" saga.

DNR Secretary J. Charles Fox has not made a final decision on details of the legislation, but a proposal is expected during the General Assembly's session, Ms. Lynch said.

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