By Rona Kobell
August 12, 2002
Since a state-convened panel recommended poisoning a Crofton pond to rid it of the northern snakehead, fisheries experts at the state Department of Natural Resources have been planning the demise of the Asian interloper that can breathe air, slither on its fins and survive on land for several days.
They have discovered that eradicating the snakehead is not as simple as dumping a fish-killing substance into the pond, what with bureaucratic hurdles and much of the agency's staff on vacation. And although DNR Secretary J. Charles Fox gave the go-ahead last week, the agency can't apply the poisons because it doesn't have the pond owners' permission.
"It's a very large logistical problem," said Steve Early, program director for the DNR's restoration enhancement program. "And the date keeps jumping on me. It's a sliding schedule. And the people are sliding with it."
Because Maryland has not used a fish poison to eradicate an exotic invasion in decades, the fisheries managers are writing much of the plan as they go. Fisheries experts are planning to use two herbicides - glyphosate, commonly sold as Roundup, and diquat dibromide - to kill all vegetation in the pond and lower the oxygen levels. About a week later, they will apply the root-based rotenone, which in recent lab tests killed juvenile snakeheads within hours.
The snakehead was discovered in the pond in June. A local man admitted to DNR police that he dumped two snakeheads - one male and one female - into the pond two years ago after they outgrew his aquarium. By last month, when biologists caught more than 100 juveniles in the pond, the state's scientific panel urged the DNR to apply the poison before stormy weather carries the fish to the Little Patuxent River, 75 yards away.
The multiagency undertaking has been neither quick nor easy. First, the DNR needed permits from the Maryland Department of the Environment to use the chemicals. Then, it needed to make sure that enough people were certified to apply the chemicals - a function the state Department of Agriculture performs. The workers, who will pump the chemicals into the pond from boats, will have to wear respirators and needed to learn to use them, and get health evaluations.
Early hit a snag when he learned that diquat can be applied to only half the pond at one time, with the other half applied two weeks later, to preserve fish populations. So the staff had to apply for an exception to the permit so they could use the dose of diquat all at once. Once the herbicides hit the pond, biologists with nets will be on hand to catch the pond's many turtles.
"The turtles will come out," said DNR fisheries service director Eric Schwaab. "We'll be washing off the turtles and taking them to another place."
About a week after applying the herbicides, the oxygen levels in the pond will drop to nearly zero, killing some of the fish and creating optimal conditions for applying rotenone. The staff determined it would need about 17 gallons of rotenone to treat the pond. Rotenone comes in a concentrate, so the biologists will have to mix it.
Disposal of dead fish will begin the day after the DNR applies the herbicides and will continue every day for weeks. Biologists will bag most of the fish in industrial trash bags and take them to the Anne Arundel County landfill in Millersville, where they will be buried.
"We have to call them up 24 hours in advance. They have to dig a hole for us," Early said.
Those that float to the surface in good condition - dead but not decomposing - will escape the landfill and instead be treated with formaldehyde. Several reference collections have requested snakehead specimens for further study, and the DNR likely will keep some, too.
DNR officials also had to figure out whom to notify at the various agencies. In addition to the landfill, the DNR will have to call Anne Arundel County's health, fire and police departments 24 hours before they begin. Officials also will notify all the businesses nearby, among them a Chinese restaurant, a bicycle shop and a Dunkin' Donuts shop.
"I'm sure if I don't bring doughnuts to the pond, I'll be in trouble," joked Early, who said the best time to apply the poison is shortly after dawn.
But the DNR can't proceed without permission from the pond owners, who are concerned about their liability in the event of lawsuits and want better protection from the state. The wait has been frustrating, especially because of a weeklong stretch of sunny, dry days - the best conditions for the herbicides and rotenone. "We were ready to go," Schwaab said. "Certainly the staff has been frustrated, but certainly that doesn't mean we don't understand the concerns of these landowners."
Negotiations are continuing, and officials say they hope to take action this week.
Local residents, knowing the end for snakehead is near, have been stopping by the pond for a last look.
Yesterday, Keith Nicholson brought his children to the pond where he had fished most of his life for bluegills and crappie. The Odenton masonry contractor said he wasn't sorry that the pond would be poisoned.
"They gotta get rid of that fish," he said, "if it can do what they say it can do."
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