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Blackwater Refuge Now Nutria-Free

Marsh-Demolishing Rodent Fended Off Earlier Efforts

By David A. Fahrenthold
Washington Post Staff Writer
Wednesday, November 17, 2004; Page B01

CAMBRIDGE, Md. -- After struggling for decades against an orange-toothed rodent that is eating the state's marshes, authorities in Maryland have claimed their first major victory over the nutria.

The animals, which are blamed for thousands of acres of vanished wetland across the state, have been eliminated from their former stronghold in Blackwater National Wildlife Refuge, officials said.

Nutria ate through about half of the marshland at the Blackwater National Wildlife Refuge, and the animals remain elsewhere in Maryland. (Robert A. Reeder -- The Washington Post)

All it took was two years, $2 million and 15 trappers working in chest-deep muck here on the Eastern Shore. In all, about 8,300 nutria were killed during the eradication, which officials said was planned like a military campaign, using Global Positioning System equipment.

Although nutria remain in the state, Maryland is being lauded as a rare success story in the government's fight against the pest, which has colonized states from the Chesapeake Bay to Oregon.

"We proved it can be done," said Jonathan McKnight, an official with the Maryland Department of Natural Resources.

The Blackwater refuge originally contained about 13,000 acres of marshland, situated near the Chesapeake in Dorchester County. Nutria were introduced there when a few of the South American animals either escaped or were released from a federal fur research project in 1943.

For the nutria, which resemble waddling beavers with naked tails, the area turned out to be a garden spot. There were huge expanses of a marsh plant they love, called three-square bulrush.

For the bulrush, and the numerous species of birds, fish and mammals that lived in the bulrush marshes, the news was not so good. Nutria act like a "mammalian lawn mower," in the words of scientist Robert A. Thomas, a professor at Loyola University in New Orleans -- eating the plants, roots and all, and leaving huge stretches of bare mud.

Without roots to hold it, in many places the mud simply washed away. About half of the refuge's marshland, a crucial pollution filter that scientists call the "kidneys" of the Chesapeake, had become open water by the 1990s.

In monetary terms, nutria cause about $2.8 million worth of economic damage annually by reducing opportunities for hunting, fishing and hiking, according to a report by the Department of Natural Resources.

Aiming to reduce this damage, authorities first offered rewards to trappers who caught nutria: $1.50 apiece.

But there was a flaw. When nutria became difficult to find, trappers decided the rodent wasn't worth their time. Any remaining animals -- blessed with an ability to produce more than 10 young in a year -- would then quickly repopulate.

"It's sort of like a whack-a-mole game," said Steve Kendrot, an official with the U.S. Department of Agriculture who was in charge of Blackwater's trapping efforts.

Government officials also tried to make nutria into a dinner-table delicacy. That, too, failed: They found that people who will eat nutria are pretty much the same people who eat muskrat -- not much of a mass market.

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