Chesapeake Bay Nutria Eradication Project
Northeast Region


Thumbnail of Chesapeake Bay Nutria Eradication newsletter, "Nutria News"

Announcing the first edition of Nutria News,
the newsletter that keeps you up-to-date on
progress in the nutria eradication effort in
the Chesapeake Bay area.

Nutria (Myocastor coypus)
Photo of a nutria. Wet fur, orange teeth, beady eyes. The size of a large cat.

What are nutria?

Nutria are invasive, non-native, semi-aquatic, South American rodents first released into Dorchester County, Maryland in 1943. Since nutria did not evolve in Maryland’s wetland ecosystems, there are no predators or natural conditions that control their population. Since their release, nutria numbers increased dramatically, invading least eight Maryland counties and unknown portions of Delaware and Virginia

Populations on 10,000 acres of the Chesapeake Marshlands National Wildlife Refuge Complex (CMNWRC), Blackwater Unit grew from less than 150 animals in 1968 to as many as 50,000 in 1998. Populations in the Chesapeake Bay region were incalculable, but may have exceeded several hundred thousand.

How do they affect the landscape?

Loss or degradation of Maryland’s coastal marshes has expanded to alarming proportions, not only affecting wildlife but also citizens of the Chesapeake Bay region. It is estimated that between 45 - 65 percent of the Maryland’s wetlands have vanished since the 1700’s.

Although nutria are not the sole reason for marsh loss, they have greatly exacerbated the problem. Blackwater has lost 50 percent of its wetlands (5,000 acres) since the introduction of nutria.

Feeding by nutria damages or destroys the root mat that binds the marsh together. When this fibrous root network is lost, marshlands are quickly reduced to unconsolidated mudflats. These areas, in turn, are highly susceptible to erosion and are eventually converted to open water. This downward spiraling not only harms the marsh but the wildlife that depend on them.

Nutria damage to the root mats in a marsh, also known as an "eatout".
Image of Nutria damage

Finfish, shellfish, birds, mammals, reptiles and amphibians feel the impact of nutria. The marshlands function as sediment and contaminant traps, and are nursery grounds for the largest and most productive estuary in North America. The health of the Chesapeake Bay is dependent on the quality of its marshes.

What does it cost us?

The economic impacts resulting from established nutria populations are all-encompassing. Agriculture, commercial fisheries and the seafood industry, ecotourism, recreational fishing, hunting, and trapping, and countless other businesses and industries that rely on healthy wetlands all suffer ill effects.

It is estimated that wetland degradation due to nutria was responsible for $4 million of lost revenue in Maryland during 2004, with predicted losses to exceed $30 million per year by 2050. Read about the economic affects in the Southwick Report.

How did the Chesapeake Nutria Eradication Project come into existence?

Efforts to control nutria began in the mid-1950’s shortly after the first animals that had been introduced for research and fur-farming were released or escaped from captivity. Varying levels of control were achieved over the next twenty years, but populations continued to expand despite these efforts. In the mid-1970s, populations crashed during the severe winters of 1977-78. However, during the next decade, the nutria population significantly increased to the point where these ravenous invasive rodents were contributing to unprecedented marsh loss. In 1989, Blackwater National Wildlife Refuge initiated a trapper rebate program whereby trappers were paid $1.50 for each nutria they killed. The money was then applied to offset the cost of leasing federal lands for muskrat trapping. In 1990, both the Maryland Department of Natural Resources (MDNR) and U.S. Fish and Wildlife Service (FWS) began research projects to estimate nutria numbers.

Multi-agency partnerships are frequently formed to solve natural resource issues that would be difficult for any agency to tackle alone. In 1993, the MDNRand the FWS established the first multi-agency task force to investigate potential approaches to combat feral nutria populations. In 1994, Dr. Morris Gosling visited from Great Britain where he had successfully led a program to eradicate nutria. Dr. Gosling assessed the problem and affirmed that eradication was an achievable goal. Dr. Gosling stated that nutria could be controlled in Maryland if additional information were collected on how nutria behave and reproduce in Maryland’s habitats which are distinctly different from habitats found in Great Britain. Two major questions, however, needed to be answered before Congress would appropriate funding: “Were nutria a major factor in causing marsh loss?” and “If nutria were eradicated, would the marsh recover?” In 1995, MDNR and FWS, with assistance and direction from the U.S. Geological Survey (USGS), initiated a study that statistically addressed these two questions and provided scientific proof that nutria were the primary cause of recent marsh loss and that the damaged marshes would recover within one year after their removal.

In June 1997, the DNR and FWS convened the “Nutria Control Summit” in which representatives from 17 federal, state, and private organizations were invited to develop ideas for nutria eradication in Maryland. This effort culminated in July 1998 with the development of a 3-year pilot plan entitled Marsh Restoration: Nutria Control in Maryland to evaluate nutria eradication. The objectives of the plan were to: 1) develop methods and strategies to reduce nutria populations in Chesapeake Bay wetlands to the point where they are unable to maintain a sustainable population; 2) restore marsh habitats; and 3) promote public understanding of the importance of preserving Maryland’s wetlands. Strategies included development of accurate population estimates, determining effective trapping strategies to maximize nutria harvest and minimize impacts to non-target species, evaluating the effects of population control on nutria home range and movement patterns, determining how population control affects nutria reproductive behavior, and determining if the health of nutria populations would be influenced by intense harvest pressure

The plan suggested a 3-pronged approach including management, research, and public education. The overall budget necessary to implement the plan over 3 years was estimated at $3.8 million. However, the partners identified $902,280 of in-kind contributions to support this initiative and sought additional funding of $2.9 million from federal, state and private sources to implement the plan. First year implementation was estimated at almost $1.4 million.

H.R. 4337 was introduced by Congressman Wayne Gilchrest during the 105th Congress and was enacted as Public Law 105-322 on October 30, 1998. PL 105-322 authorized the Secretary of the Interior to appropriate up to $2.9 million, beginning in fiscal year 2000, to achieve the objectives of the nutria plan. On October 30, 1998, President Clinton signed PL 105-322, which authorized the Department of the Interior to expend up to $2.9 million for the three-year pilot project. The Pilot Project began on January 1, 2000 and ended in December 2002. The project's management team included the Maryland Cooperative Fish and Wildlife Research Unit, Maryland Department of Natural Resources, University of Maryland Eastern Shore, Tudor Farms, and the U.S. Fish and Wildlife Service.

On February 3, 1999, President Clinton signed Executive Order 13112 to control invasive species and to minimize the economic, ecological, and human health impacts that invasive species cause to agricultural crops and natural ecosystems. In 1999, the partners were also successful in obtaining a Capacity Building Grant from the U.S. Department of Agriculture for almost $300,000 for a portion of the research component of the nutria plan. In the fiscal year 2000 budget, Congress earmarked $500,000 in the U.S. Fish and Wildlife Service budget to support implementation of the first year of the pilot program. To implement the first year of the 3-year pilot program at a reduced scale, the partners agreed to combine these resources (approximately $800,000). As of March 2000, the partnership had expanded and included 23 federal, state, and private partners.The pilot program answered the elemental questions of whether or not nutria can indeed be eradicated from the Chesapeake Bay ecosystem, and what level of effort is required to do so.

In April 2002, the eradication phase was fully implemented. USDA Animal and Plant Health Inspection Services (APHIS), Wildlife Services, assumed primary responsibilities for project implementation. The total cost of the nutria project, since its inception in 2000, has been approximately $13.8 million through fiscal year 2011.

Using APHIS staff, the project has expanded far beyond the Blackwater Unit into the state and privately-owned lands, tolalling approximately 150,000 acres. In order to fully eradicate nutria from the Delmarva Peninsula, it will be necessary for the project to expand into the 250,000 remaining wetland acred on Delmarva. The challenge ahead is for the project to continue to expand into surrounding marshlands while preventing re-infestation of the National Wildlife Refuge and previously trapped state and private lands. This will require the trapping team to work in much larger areas and expand the trapping zone on a much broader front. The project has demonstrated that eradication is achievable. We must now complete the eradication effort in order for the tidal marshes of the Eastern Shore of the Chesapeake Bay and beyond to be saved and restored.

Without this considerable effort, nutria will continue to destroy wetlands throughout the region. Recognizing this, President Bush signed the Nutria Eradication and Control Act of 2003, which authorizes the expenditure of $4 million per year for five years to eradicate Nutria from the Chesapeake and Delaware Bays.

The nutria eradication project is overseen by the Nutria Management Team, consisting of the U.S. Fish and Wildlife Service Chesapeake Bay Field Office, Chesapeake Marshlands National Wildlife Refuge Complex , U.S. Department of Agriculture Animal and Plant Health Inspection Service Wildlife Services , the Maryland Department of Natural Resources, the U.S. Geological Survey, the University of Maryland Eastern Shore, and Tudor Farms.

Visit our Project Partners page to contact members of this project.



Last updated: March 7, 2013