Invasive Species Council of Manitoba

Zebra Mussels(Dreissena polymorpha)

History: Native to the Black and Caspian Sea region of Eurasia. A cargo ship traveling to the Great Lakes in the 1980s is the likely point of introduction to North America. By 1990, Zebra Mussels had been found in all the Great Lakes.  The invertebrate was reported in 2010 in the United States portion of the Red River watershed in Wahpeton, North Dakota. In October, 2013, zebra mussel adults were confirmed in the southwest section of Lake Winnipeg in Manitoba.

Physical Description

General: Zebra Mussels are small invertebrates named for the striped pattern of their shells. Colour patterns can vary to the point of having only dark or light coloured shells and no stripes. Size is less than 50 mm (2") long, most are around 30mm (1 ¼") or smaller. When placed on a surface Zebra Mussels are stable on their flattened underside. They are typically found attached to objects, surfaces, or each other by threads underneath the shells.


Zebra Mussels are notorious for colonizing and constricting flow through water supply pipes of power plants and industrial facilities. They can also have profound effects on the ecosystems they invade through reducing the amount of food available to other species. Native Mussel populations have decreased dramatically where Zebra Mussels are present.


Zebra Mussels have been expanding their range into Manitoba,  moving northwards from Minnesota. In Ontario they have been spreading into the western side of the province. Check boats, trailers and other equipment while moving between lakes.  Report any sightings to the ISCM.  (This report will also be submitted to the Province of Manitoba).Zebra Mussels

[A] Zebra Mussels colonizing on another aquatic invertebrates. [B] Zebra Mussels attached to vegetation. [C] A clump of Zebra Mussels attached to a cluster of Eurasion watermilfoil. [D] A Zebra Mussel in comparisonto a finger. [E] A front and back view of a Zebra Mussel.

Photos: [A] Randy Westbrooks, U.S. Geological Survey, [B] [C] F. Koshere WISDNR[D] [E] Amy Benson, U.S. Geological Survey,

For more information or to report a sighting, call: 1-87-STOP-AIS-0 or 1(877)-867-2470


Zebra Mussels ISCM Fact Sheet


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