The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Myocastor coypus
Myocastor coypus

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Myocastor coypus (Molina, 1782)

Common name: nutria

Taxonomy: available through www.itis.govITIS logo

Identification: Large rodent, resembling both native beavers and muskrats. The nutria has a long, thin round tail which distinguishes it from the beaver which has a flat tail and the muskrat which has a laterally flattened tail. They are also distinguishable by their orange teeth and white whiskers.

Size: Nutria can grow as long as 2 feet and weigh as much as 20 pounds

Native Range: Southern South America

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Myocastor coypus are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AL194919563Mobile Bay; Mobile-Tensaw; Perdido Bay
AR1958201932Bayou Bartholomew; Bayou Macon; Bayou Meto; Big; Bodcau Bayou; Cache; Cadron; Dardanelle Reservoir; Fourche La Fave; Frog-Mulberry; Lake Conway-Point Remove; L'anguille; Little Missouri; Little Red; Little River Ditches; Loggy Bayou; Lower Arkansas; Lower Arkansas-Maumelle; Lower Black; Lower Little Arkansas; Lower Mississippi-St. Francis; Lower Ouachita-Bayou De Loutre; Lower Ouachita-Smackover; Lower Saline; Lower St. Francis; Lower White; Lower White-Bayou Des Arc; Mckinney-Posten Bayous; Middle White; Petit Jean; Upper Ouachita; Upper Saline
CA189920199Lower San Joaquin River; Middle San Joaquin-Lower Chowchilla; Middle San Joaquin-Lower Merced-Lower Stanislaus; San Joaquin; San Joaquin Delta; Santa Clara; Upper Merced; Upper Stanislaus; Upper Tuolumne
DE199320053Brandywine-Christina; Broadkill-Smyrna; Nanticoke
FL1956202121Apalachicola; Aucilla; Blackwater; Choctawhatchee Bay; Crystal-Pithlachascotee; Daytona-St. Augustine; Hillsborough; Lower St. Johns; Lower Suwannee; Oklawaha; Peace; Pensacola Bay; Perdido; Perdido Bay; Tampa Bay; Upper St. Johns; Upper Suwannee; Vero Beach; Waccasassa; Withlacoochee; Yellow
ID195819612Middle Snake-Payette; St. Joe
IA195719571Keg-Weeping Water
LA1940202032Amite; Atchafalaya; Atchafalaya - Vermilion; Bayou Cocodrie; Bayou Sara-Thompson; Bayou Teche; Black Lake Bayou; Boeuf; Calcasieu-Mermentau; East Central Louisiana Coastal; Eastern Louisiana Coastal; Lake Maurepas; Lake Pontchartrain; Liberty Bayou-Tchefuncta; Lower Calcasieu; Lower Grand; Lower Mississippi-New Orleans; Lower Red-Lake Iatt; Lower Sabine; Mermentau; Mermentau Headwaters; Middle Red-Coushatta; Red Chute; Tangipahoa; Tensas; Tickfaw; Toledo Bend Reservoir; Upper Calcasieu; Vermilion; West Central Louisiana Coastal; West Fork Calcasieu; Whisky Chitto
MD1943202114Chester-Sassafras; Choptank; Conococheague-Opequon; Gunpowder-Patapsco; Lower Potomac; Middle Potomac-Anacostia-Occoquan; Middle Potomac-Catoctin; Nanticoke; North Branch Potomac; Patuxent; Severn; Tangier; Upper Chesapeake Bay; Youghiogheny
MA200220192Charles; Concord
MN194719492Cannon; Lower Rainy
MS1956200513Bayou Pierre; Big Sunflower; Black; Buffalo; Coldwater; Coles Creek; Deer-Steele; Horn Lake-Nonconnah; Lower Mississippi-Helena; Lower Mississippi-Natchez; Mississippi Coastal; Pascagoula; Upper Yazoo
MO195820053Little River Ditches; Lower St. Francis; New Madrid-St. Johns
NE194419582Big Papillion-Mosquito; Upper Republican
NV194420192Carson Desert; Truckee
NM193720204Monument-Seminole Draws; San Simon; Upper Pecos; Upper Pecos-Long Arroyo
NY198919891Upper Hudson
NC1958202110Albemarle; Contentnea; Lower Cape Fear; Lower Roanoke; Lower Tar; Middle Neuse; Pamlico; Pamlico Sound; Upper Neuse; Upper New
OH1936196110Auglaize; Black-Rocky; Grand; Little Miami; Lower Maumee; Lower Scioto; Mahoning; Raccoon-Symmes; Tuscarawas; Upper Great Miami
OK198919894Cache; Middle Washita; Upper Little; Upper Washita
OR1936202138Alsea; Clackamas; Coast Fork Willamette; Coos; Coquille; Lower Columbia; Lower Columbia-Clatskanie; Lower Columbia-Sandy; Lower Grande Ronde; Lower Owyhee; Lower Rogue; Lower Snake-Asotin; Lower Willamette; Mckenzie; Middle Columbia-Hood; Middle Columbia-Lake Wallula; Middle Fork Willamette; Middle Rogue; Middle Willamette; Molalla-Pudding; Necanicum; Nehalem; North Santiam; North Umpqua; Pacific Northwest Region; Powder; Siletz-Yaquina; Siltcoos; Siuslaw; South Santiam; South Umpqua; Tualatin; Umpqua; Upper Deschutes; Upper Grande Ronde; Upper Willamette; Wilson-Trusk-Nestuccu; Yamhill
TN199620214Lower Hatchie; Lower Mississippi-Memphis; Obion; Wolf
TX1945202194Amistad Reservoir; Aransas; Aransas Bay; Austin-Oyster; Austin-Travis Lakes; Baffin Bay; Big Bend; Bois D'arc-Island; Bosque; Brady; Buffalo-San Jacinto; Caddo Lake; Cedar; Central Laguna Madre; Chambers; Concho; East Fork San Jacinto; East Fork Trinity; East Galveston Bay; East Matagorda Bay; Elm Fork Trinity; Elm-Sycamore; Guadalupe; Hondo; Lake Fork; Lake O' the Pines; Lavaca; Leon; Little; Little Cypress; Lower Angelina; Lower Brazos; Lower Brazos-Little Brazos; Lower Colorado; Lower Colorado-Cummins; Lower Devils; Lower Guadalupe; Lower Neches; Lower Pecos; Lower Rio Grande; Lower Sabine; Lower San Antonio; Lower Sulphur; Lower Trinity; Lower Trinity-Kickapoo; Lower Trinity-Tehuacana; Lower West Fork Trinity; Lozier Canyon; Medina; Middle Brazos-Lake Whitney; Middle Brazos-Palo Pinto; Middle Colorado; Middle Colorado-Elm; Middle Guadalupe; Middle Neches; Middle Sabine; Navasota; Navidad; North Bosque; Pecan Bayou; Pine Island Bayou; Red-Lake Texoma; Sabine Lake; San Ambrosia-Santa Isabel; San Bernard; San Gabriel; San Jacinto; San Marcos; San Saba; South Laguna Madre; South Llano; Spring; Sulphur headwaters; Toledo Bend Reservoir; Turkey; Upper Angelina; Upper Clear Fork Brazos; Upper Colorado; Upper Devils; Upper Frio; Upper Guadalupe; Upper Neches; Upper Nueces; Upper Sabine; Upper San Antonio; Upper Trinity; Village; West Fork San Jacinto; West Galveston Bay; West Matagorda Bay; West Nueces; West San Antonio Bay; White Oak Bayou; Yegua
VA195820083Albemarle; Hampton Roads; Pokomoke-Western Lower Delmarva
WA1935202118Chief Joseph; Deschutes; Duwamish; Grays Harbor; Lake Washington; Lewis; Lower Columbia; Lower Columbia-Clatskanie; Lower Columbia-Sandy; Lower Cowlitz; Lower Skagit; Lower Yakima; Nisqually; Nooksack; Puget Sound; Snohomish; Strait of Georgia; Upper Chehalis
WV201220121Upper Guyandotte

Table last updated 1/26/2022

† Populations may not be currently present.

Means of Introduction: Imported into Louisiana for fur farming.

Status: Feral populations are established in several states such as Louisiana, Maryland, Oregon, Texas, and Washington.

Impact of Introduction:
Summary of species impacts derived from literature review. Click on an icon to find out more...

EcologicalEconomicHuman Health

Over-grazing of wetland habitats.

Author: Fuller, P.

Revision Date: 1/13/2020

Citation Information:
Fuller, P., 2022, Myocastor coypus (Molina, 1782): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1089, Revision Date: 1/13/2020, Access Date: 1/26/2022

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2022]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [1/26/2022].

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