Katrina Weakened, But Didn't Wipe Out, Invasive Rodents

September 9, 2005

Hurricane Katrina's path of destruction dealt at least a temporary setback to the nutria, the South American rodent species that is devouring wetlands along the Gulf of Mexico, according to experts.

Scientists believe decades of wetlands loss in the Gulf region—due in part to the voracious appetites of the rodents—made Hurricane Katrina's destruction worse.

"Some of the storm protection that nature provides from wetlands, especially in southeast Louisiana, that flood protection, it just wasn't there," said Justin Baker, a biologist with the Louisiana Department of Wildlife and Fisheries in New Iberia.

Baker heads up a program to reduce the numbers of the invasive rodents with an incentive program: Registered trappers are paid four dollars (U.S.) for every nutria tail they deliver to collection agencies. The target is to kill 400,000 nutria each year.

Baker's department encourages trappers by touting the virtues of nutria fur, which is similar to that of beaver, and by circulating recipes for nutria meat.

Adult nutria weigh about 15 pounds (7 kilograms), falling in size between a muskrat and beaver. Their prolific nature—a female can produce two litters of five or six young a year—and insatiable appetite for wetland vegetation are wreaking havoc along the U.S. Gulf Coast.

In April 2005, an aerial survey found 53,475 acres (21,641 hectares) of nutria-caused wetland damage in Louisiana. That figure is nearly half the damaged acreage surveyed when the control program started in 1998.

Jacoby Carter is an ecologist who studies nutria at the U.S. Geological Survey National Wetlands Research Center in Lafayette. He said Katrina's impact on the rodent was likely significant but temporary.

"It most likely greatly reduced the populations in the affected areas, [but] it probably did not wipe them out," he wrote in an e-mail to National Geographic News. "Since nutria do swim, some probably found refuge on floating items."

Given the rodents' prolific nature, their recovery is certain, Carter added.

Wetland Destruction

Baker said that nutria damage to wetlands stems from their feeding habits: Unlike muskrats, they eat everything in sight before moving on. "They literally eat themselves out of house and home," he said.

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