Nutria - Myocastor coypus

Contact Information

Portland State University
Center for Lakes and Reservoirs
PO Box 751 - ESR
Portland OR 97207-0751

Please click here for information on the results of the 2013 Nutria Management in the Northwest Workshop

Please click here for information on the results of the 2007 Nutria Management in the Northwest Workshop


The nutria, Myocastor coypus, is a large semi-aquatic mammal that is native to South America.  It has been introduced to numerous countries around the world, primarily for fur farming.  Nutria fur farms in the United States originated as early as 1899.  Nutria were initially imported to California, Oregon, Washington, Michigan, New Mexico, Louisiana, Ohio, and Utah for the fur farming industry.  Various government agencies subsequently transported nutria to Alabama, Arkansas, Georgia, Kentucky, Maryland, Mississippi, Oklahoma, and Texas with the intent of using the species to control unwanted vegetation.  The common practice was to release nutria into the wild when fur industries failed, and the species routinely escaped from the farms as well.  Feral populations have been reported in forty states across the country, but known populations exist in about twenty states.  Of these twenty states, at least fifteen are known to have stable or increasing populations.

Wetland and Riparian Impacts of Nutria (Myocastor coypus) and Management Planning for the Pacific Northwest

The nutria (Myocastor coypus) is an invasive rodent that has established feral populations in wetland and riparian habitats in the Pacific Northwest. Nutria populations have existed in the region since the late 1930s, and populations continue to grow and spread. Some research suggests that the highest densities of nutria in the world are in Oregon's freshwater marshes. The Oregon Aquatic Nuisance Species Management Plan lists nutria as a management class 3 species, which acknowledges that the species is established and has negative impacts throughout the state. This classification also indicates that no management plan exists, and that further evaluation and research should be pursued to prevent further establishment. The goal of this project is to provide the framework for a regional nutria management plan. The project will address three immediate needs concerning the nutria problem in the Pacific Northwest: coordinated regional communication, accurate distribution information, and evaluation of impacts on restoration sites. The scope of work for the project will include three activities: a regional nutria management workshop, a current distribution map of nutria in the Pacific Northwest, and a field study of the ecological and economic impacts on wetland and riparian restoration sites resulting from nutria damage.

Report on Nutria Management and Research in the Pacific Northwest .pdf

Nutria feeding on lawn from Center For Lakes and Reservoirs on Vimeo.