Return to the Wild - Evolving perspectives on Canadian wildlife
The zebra mussel is not native to Canada but now flourishes in the Great Lakes and beyond.

Did you know?

In one year, a female adult zebra mussel can produce from 30,000 to one million eggs.

Scientific name: Dreissena polymorpha
Average length: 2 cm–4 cm
Average lifespan: 2–4 years
A woman holds a stick with many zebra mussels attached to it.

Canadian Geographic articles

Learning to live with zebra mussels

Geo-Watch section of the magazine
May/June 1992

The advancing spread of the zebra mussel through the Great Lakes was examined in “Learning to live with zebra mussels,” in the “Geo-watch” section of the May/June 1992 issue. At the time, some areas were recording the highest concentrations of the opportunistic mussels in the world.

Described in the article as opportunistic bivalves originally from the Black Sea, they were introduced to Lake Ontario and Lake Erie in the 1980s from the bilges of foreign freighters. They found conditions for growth ideal in Canada and their most recent moves have taken them into Lake Superior, the St. Lawrence River as far east as Québec, and to Lake Muskoka in the cottage country of southern Ontario.

The western end of Lake Erie is described in this article as a “carpet of zebra mussels” with up to 350,000 per square metre. The typical concentration in Europe is 5,000 per square metre. However, this population in Lake Erie is expected to thin out as the food supply reduced.

A federally funded study by University of Toronto scientists in 1991 evaluated the current preventive measures being used — mid-ocean exchanges of freshwater for saltwater in bilges to remove or kill organisms in ships bound for the seaway. The study found that even after ships complied with the voluntary rinse, 33 percent still carried organisms that could live in the Great Lakes.

The few ways to destroy the mussels include ultraviolet rays, chemicals and pathogens. However, none of these are safe and/or efficient thus the author concludes that we will just have to learn to live with them.

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