Puget Sound Shoreline, Rae A. McNally

Nutria are an invasive species of rodent that are threatening the health of marine and freshwater habitats in the Pacific Northwest.

Often mistaken for a beaver, nutria  are smaller—about the size of a cat. Adults weigh less than 20 pounds and are about 2-feet long. They have dark fur, but not as dark as a beaver. Their tails are thin, round and pointed at the tip, unlike the flat, broad tail of a beaver. Nutria spend much of their time in the water and are highly adapted to a semi-aquatic existence. 

What’s the problem?

Using their large front teeth, nutria gnaw voraciously on the roots of fresh and saltwater marsh plants, which are important habitat for many native fish and waterfowl. Their preferred diet consists of young aquatic plants in both salt and freshwater environments. In Skagit County, nutria have been burrowing into dikes, potentially undermining the flood control structures that protect much of Skagit Valley ’s farm fields, homes and infrastructure. Farmers are understandably worried about crops that nutria might feed on. In the Southeastern U.S., nutria rats have raised havoc in marshlands, rice fields and rivers—especially in Louisiana and Texas .  

Nutria eat about 25 percent of their body weight daily. They are opportunistic feeders with an extremely varied diet. In marsh habitats, nutria forage directly on the vegetative root mat, which can result in an “eat out”—an area devoid of vegetation as soil is washed away. Nutria also feed on crops, lawn grasses and ornamental plants adjacent to aquatic habitats.

The Washington Department of Fish and Wildlife classifies nutria as a prohibited species. Prohibited species may not be released into the wild. It is also unlawful to release captured nutria back into the wild, or to transport nutria without a permit from the department.

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How did nutria get to Washington State?

Native to the southernmost countries of South America, nutria rats were originally introduced in the Washington in the 1930s for the fur trade. The market for nutria fur collapsed, and many escaped or were released. Established populations exist mainly in lowland areas of Southwest Washington, although they are turning up as far north as Skagit County .  

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Where are nutria in the Puget Sound region?  

  • Skagit County
  • Snohomish County
  • King County
  • Capitol Lake , Olympia , Thurston County

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What’s being done in Washington State?

The Department of Fish and Wildlife published a report called Living with Nutria, which provides facts about nutria, its legal status, describes things you can do to minimize conflict with them and describes methods for trapping and control.

In Skagit County . A derailed effort to survey and trap these destructive rodents in Skagit County got back on track thanks to funding from diverse groups in the county. Agricultural and conservation groups, county agencies, several dike districts and the business community responded to a funding challenge from the Washington chapter of The Nature Conservancy.

In early 2000, the groups pulled together nearly $50,000, which was enough to get a trapper back out in the field. It was also enough to launch a much-needed survey to better understand the extent of the nutria rat population in the county. A dog specifically trained to sniff out nutria was brought in from Maryland to help with the survey efforts.

>> Learn more

For more information about the Puget Sound Partnership's Aquatic Nuisance Species Program, contact Kevin Anderson, 360.725.5452.

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Highlights
Nutria hunted to save wetlands
4-minute viideo shows how nutria infestations have adversely affected Maryland's Eastern Shore.
>> View video