Press Releases | DNR Press Room | Search DNR | DNR Home
Maryland Department of Natural Resources
Rodents Consuming Vital Chesapeake Bay Marshlands; Economic Losses Could Exceed $35 Million in Future Decades
ANNAPOLIS - A new economic evaluation of the effects of an escaped population of Nutria, -- an exotic South American rodent that is spreading across Chesapeake Bay marshes -- shows that the rat-like creatures could have an enormous cost in lost revenue to the State of Maryland, as well as a devastating ecological impact to the Chesapeake Bay.

The study, performed by Southwick Associates, an independent economic consulting group and commissioned by the Maryland Department of Natural Resources (DNR) Wildlife and Heritage Service (WHS) outlines the damage that nutria are causing and the effects they will have upon the Maryland economy.

Nutria are large aquatic rodents native to South America. They became established in Maryland when a few animals escaped from a fur farm in the 1930s. Unlike the smaller native muskrat which grazes on marsh grasses, nutria literally consume tidal marshlands, leaving mudflats in their place. Scientists believe that there are as many as 50,000 nutria in the wetlands of the Chesapeake’s Eastern Shore.

“As more and more acres of Chesapeake Bay marshes are lost, the resulting declines in commercially and recreationally-valuable species takes a measurable economic toll on the State of Maryland and its citizens.

“This confirms our worst fears and supports the necessity to act aggressively when controlling the nutria population,” said Jonathan McKnight, Associate Director for Habitat Conservation for DNR’s Wildlife & Heritage Service. “If the nutria are allowed to continue to destroy the Bay’s marshes, we will feel the economic pain in lost fisheries, tourism, and jobs.”

State and Federal agencies have formed the Chesapeake Nutria Partnership to battle the rat-like invaders. Since 2002 DNR has worked with trappers from the U.S. Department of Agriculture to ply the marshes of Dorchester County, trapping nutria and establishing a “nutria-free zone” in what was once the most heavily infested marshland in the Chesapeake.

“We have been able to clear the Blackwater National Wildlife Refuge of nutria,” said Kevin Sullivan, State Director of Wildlife Services for the U.S. Department of Agriculture. “We’ve proven that nutria can be eradicated in a large area, and we’ve seen a remarkable recovery in damaged wetlands. The next step is to accelerate our efforts and make the entire Chesapeake Bay a nutria-free zone.”

“Often when we look at ecological effects, we have to ask people to make value judgments,” said John Wolflin, Director of the U.S. Fish and Wildlife Service Chesapeake Bay Field Office. “But in this case the damage is sufficiently extreme that it has been possible to predict the impacts in dollar terms. And the numbers are sobering.”

Included in the report’s findings:


The Maryland Department of Natural Resources (DNR) is the state agency responsible for providing natural and living resource-related services to Maryland citizens and visitors. DNR manages more than 435,000 acres of public lands and 17,000 miles of waterways, as well as Maryland's wildlife and fishery species for maximum environmental, economic and quality of life benefits. A national leader in land conservation, the department manages natural, historic and cultural resources that attract 11 million visitors annually. DNR is the lead agency in Maryland's effort to restore the Chesapeake Bay, the state's number one environmental priority. Learn more at www.dnr.maryland.gov