Zebra and quagga mussels are closely-related mollusks that originate from freshwater lakes in Russia and Ukraine and are non-native to North America. They live in freshwater – such as lakes and rivers – and are invasive. They are known to encrust and corrode hard surfaces and cause serious harm to waters where they become established.
Fortunately, as best we know, the Okanagan is still free from invasive mussels. It’s up to us to help keep it that way.
Note: The Okanagan does have native mussels that are protected species. One being the Rocky Mountain Ridged Mussel, a much larger mussel that can grow to 12.5 cm (almost 5 inches) long, and Floater Mussels which are between 12.5 and 18 centimeters. Learn more about these mussels here (page 2).
They were first introduced to Canada’s Great Lakes region and the United States in the 1980s after ballast water was discharged by vessels traveling from Europe.
The mussels have been in the Great Lakes in Ontario and Quebec since the late 80’s and have been spreading ever since through U.S. states, including California, Nevada, and Arizona. And then in October 2013, they were discovered in Lake Winnipeg, Manitoba, and then Cedar Lake, Manitoba in October 2015.
In an effort to stop the spread, and with some 33 U.S. states now infested, B.C. and others in the Pacific Northwest (including Alberta, Saskatchewan, Washington, Oregon, Idaho and Montana) set up a perimeter defense to keep the mussels out. In October 2016, Montana discovered mussels in two reservoirs and went into full containment mode. As of 2022, the reservoirs are considered mussel-free. It’s believed this may be due to the reservoirs being drawn down enough to kill the molluscs – a solution that is not available for Okanagan Lake.
With the mussels potentially a one-day drive from B.C., the importance of prevention is more critical than ever.
It wouldn’t take long for the mussels to get established once they arrive. Each female can produce about 1 million eggs per year. And in some areas with warm waters, like Lake Mead, there have been six to eight reproductive cycles a year.
The mussels can be spread unknowingly by boaters, fishers and other well-meaning nature lovers. At their youngest stage, the invasive mussels are the size of a grain of sand. At their largest they are the size of your thumbnail (1.5 to 2 cm). They are often brought in on boats and other recreational water toys (e.g. kayaks). But they can also come in on hipwaders, fishing tackle boxes, life jackets and other objects that have spent time in infested waters.
Both invasive mussel species are sometimes referred to as “zebra” mussels because they both have light and dark alternating stripes. Quagga mussels are actually a distinct, but similar, species named after the quagga – an extinct mammal which closely resembled and was related to the zebra.
A study conducted for the Okanagan Basin Water Board found that an invasion of zebra and/or quagga mussels in the valley could impact
A study conducted for the Okanagan Basin Water Board in 2013 found the cost to our region could be at least $42 million each year in lost revenue, added maintenance of aquatic infrastructure and irreparable ecological damage. And in 2015, the Pacific NorthWest Economic Region (PNWER) estimated the cost of an invasion at $500 mill. annually to the Pacific NorthWest.