Wetland destruction typically brings violators stiff fines, or even prison. Now, biologists say the damage in one case is so severe they want a more dramatic penalty: the death sentence.
The violator in this case is a rodent from South America, the nutria.
At a time when Bay states are committed to increasing the amount of wetlands in the watershed, nutria are causing the loss of thousands of acres of Eastern Shore wetlands.
They chew away at the roots of the plants that hold together the soil of low-lying marshes. Without the root mat cementing the marsh together, the land is literally washed away with the tides.
“We’re at a critical point with these marshes,” said Robert Colona, a biologist with the Maryland Department of Natural Resources. “A lot of the resource managers down here feel that in another 10 years, we won’t have any marshes. It’s going to be gone if we don’t do anything.”
To be sure, nutria are not the sole factor at work. Sea level rise has been under way in the Chesapeake for thousands of years, even as the surrounding land gradually subsides. Gradually, the ever-rising water eats away at the marsh and other land.
But, Colona said, the nutria greatly speed the loss, and they are something that can be controlled, unlike sea level rise. “They’re the catalyst,” he said. “They’re the match you throw into the gasoline. If the sea level was rising fast enough to lose marsh at the rate we’re losing it, we would all be sitting in the top of trees right now.”
Since the 1950s, nutria have helped to turn about 6 square miles of marshes in Maryland’s Dorchester County into open water. Losses in other Eastern Shore areas are thought to measure in thousands of acres, and scientists say the rate of loss has accelerated as the nutria population has boomed.
Nutria were imported from South America in the 1930s to be raised in captivity for their fur. The effort was a failure, and by the 1940s, the rodents had either escaped or were released into the wild.
Nutria reproduce rapidly — females mature at six months and can produce multiple litters, averaging five each, during the year — and they have no natural predators in the region.
In the past two decades, their numbers on the Eastern Shore have increased exponentially. In Blackwater National Wildlife Refuge, an estimated 35,000 to 50,000 nutria occupy a 15,000-acre area. In another part of Dorchester County, an estimated 25,000 animals occupy a 7,000-acre area. Numbers have grown despite the annual harvest of roughly 25 percent to 35 percent of the population in the area.
And that’s just two parts of Dorchester County. Nutria range all the way from Kent Island to the Virginia state line; no one knows how many there are. “We don’t have a clue,” Colona said. “There’s just a lot of them.”
Evidence suggests that if they were gone, the marshes would come back. In recent years, Colona and Mike Haramis of the U.S. Geological Survey have erected 19, 100-foot-square enclosures at the Blackwater refuge. The experiment showed that the marshes usually recover, if the nutria damage is not too great.
In 1997, representatives from 17 government agencies and private organizations met at a “Nutria Control Summit,” which ultimately concluded that the best action was the outright elimination of the animals. It’s a difficult job — efforts would be futile unless the entire population is annihilated. Even a few left behind could start the problem all over again. But the job isn’t without precedent. Nutria were wiped out in Britain during the 1980s.
The task force is seeking more than $3.5 million for a pilot project — $2.9 million from the federal government, and $750,000 from others. Congress approved the concept last year, but has yet to appropriate any money.
The pilot project would test techniques for trapping nutria, support the collection of research to better understand the natural history of the nutria — something that will reveal the animals’ behavior traits — and experiment with marsh restoration techniques.
No one is certain how many years it would take to complete the job. In Britain, it took six, plus several years of follow-up monitoring to make sure the animals were, in fact, gone.
Colona said the project will be watched carefully by others: Roughly two dozen other states have problems with the rodents.