New Zealand mudsnail

Scientific Name: Potamopyrgus antipodarum

U.S. Geological SurveyCopyright Info

Identification: The shell of the New Zealand mudsnail is elongated and coils in a counter-clockwise direction. The colors of its shell vary from light brown to dark brown or gray.

Size: While this species can reach 0.5 inch (12 mm) in its native range, it is usually less than 0.25 inch (4-6 mm) in length in the Great Lakes.

Native Range: This species is native to the freshwater streams and lakes of New Zealand and its small neighboring islands.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, 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 Potamopyrgus antipodarum are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Illinois200620162Lake Michigan; Little Calumet-Galien
Michigan201320163Au Sable; Boardman-Charlevoix; Pere Marquette-White
Minnesota200520052Lake Superior; St. Louis
New York199120164Lake Erie; Lake Ontario; Oak Orchard-Twelvemile; Seneca
Ohio200620061Lake Erie
Pennsylvania200520081Lake Erie
Wisconsin200520162Lake Michigan; St. Louis

Table last updated 10/2/2019

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: This species was most likely introduced to the Great Lakes via ballast water discharge of ships from Europe, where non-native New Zealand mudsnails also reside. It may have been introduced to the western U.S. in shipments of live game fish from eastern waters. The New Zealand mudsnail tolerates dry conditions and may inadvertently be transported in or on boots or by angling and recreational equipment. This snail survives passage through animal guts, and thus can be transported by fish, birds, and other wildlife. It can also float by itself or be transported on floating plant material.

Status: The New Zealand mudsnail is established in Lake Ontario and Lake Erie, and at least present in Lake Superior. It also can be found in rivers of the western United States.

Remarks: The public is advised to decontaminate fishing and sporting equipment in order to contain existing populations and to prevent the establishment of new ones. Commercial shipping of this species is regulated.

The New Zealand mudsnail supports a number of parasites in its native range, but none have been found associated with North American populations.

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
NOAA Sea Grant GLRI Logo

Revision Date: 9/25/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, New Zealand mudsnail: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/25/2012, Access Date: 10/13/2019

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.