Invasive Mussels — An Immediate and Preventable Threat

Zebra mussels

Invasive species pose a serious risk to B.C.’s lakes and rivers, with the potential to disrupt entire ecosystems. Among the most destructive are zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis), which spread rapidly, damaging aquatic habitats, fisheries, and water systems.]

For years, the BCWF has advocated for protections against these invasive mussels, calling them “the single biggest invasive threat to our freshwater ecosystems, hydroelectric facilities, irrigation systems, and municipal water infrastructure.”

For National Invasive Species Awareness Week 2025, the BCWF is spotlighting the dangers of invasive mussels, the urgent need for prevention, and the actions we can take to protect B.C.’s freshwater resources.

What Are Zebra and Quagga Mussels?

Zebra and quagga mussels pose a major invasive threat to B.C.’s freshwater ecosystems, hydroelectric facilities, irrigation systems, and municipal water infrastructure. While not yet established in the province, contaminated boats crossing the U.S. border have resulted in dozens of close calls in recent years.

Elsewhere in Canada, zebra mussels have invaded Manitoba’s Lake Winnipeg, Ontario’s Great Lakes and inland waterways, and Quebec’s St. Lawrence River, while quagga mussels have established populations in parts of Ontario. These invasive species have caused extensive ecological and economic damage, clogging water intake pipes, outcompeting native species, and disrupting aquatic ecosystems.

Zebra mussel shells piled up on Victoria Beach (Lake Winnipeg) in May, 2018. Photo derived from CBC.

Invasive mussels on native mussels. Photo by Todd J. Morris/DFO.

How to Identify Zebra and Quagga Mussels

Zebra and quagga mussels are smaller than native mussels in B.C. Zebra mussels grow up to 3.5 cm with a D-shaped, striped shell, while quagga mussels reach 4 cm and have a rounder, less distinct shell. Both attach firmly to surfaces using strong threads, unlike native mussels that do not cling to hard surfaces.

Graphic derived for educational purposes from invasivespeciescentre.ca

Where Did They Come From?

Zebra and quagga mussels are native to the Black Sea and Caspian Sea regions of Eastern Europe. They were introduced to North America in the late 1980s through ballast water from cargo ships, first appearing in the Great Lakes before spreading rapidly across Canada and the U.S.

Highly adaptable and fast-reproducing, these mussels now infest major waterways. Their ability to attach to boats, trailers, and water intake structures has fueled their rapid expansion.

What Are The Risks?

Once introduced, zebra and quagga mussels can quickly take over freshwater systems, leading to severe environmental consequences:

Altered food web – As filter feeders, zebra and quagga mussels can rapidly change the aquatic food web by removing plankton from the water—an important food source for many invertebrates and fish
Declining fish populations – Infestations degrade fish habitat, threatening species such as lake trout, rainbow trout, and kokanee salmon
Toxin accumulation – Mussels retain waterborne toxins, exposing fish and waterfowl to illnesses like botulism
Unusable shorelines – As seen on the shores of Lake Winnipeg, mass die-offs of invasive mussels create an overwhelming stench, rendering beaches unusable
Hazardous beaches – Their razor-sharp shells make walking barefoot dangerous

Additionally, zebra and quagga mussels can cause significant economic damage:

Costly infrastructure damage – Mussels clog water intake pipes, hydroelectric dams, irrigation systems, and municipal water supplies, leading to expensive maintenance and reduced efficiency
Economic losses in tourism and recreation – Mussel infestations can disrupt boating, fishing, and waterfront activities, negatively impacting local economies that depend on outdoor recreation
Increased maintenance costs – Businesses, municipalities, and homeowners must spend significant resources on cleaning, repairing, and replacing equipment affected by mussel infestations

Preventing their introduction is critical, as once established, they are nearly impossible to remove.

In 2024, BC Hydro committed $900,000 annually to the Invasive Mussel Defence Program, with BCWF, the Pacific Salmon Foundation, and the Habitat Conservation Trust Foundation contributing another $150,000. While this funding helps, federal support is still needed.

The Invasive Mussel Defence Program funds inspections, enforcement, monitoring, and public education to prevent zebra and quagga mussels from infesting B.C.’s freshwater ecosystems.

Prevention is Key: How You Can Help

Follow Clean, Drain, Dry protocols – Always clean, drain, and dry boats, fishing gear, and equipment before moving between water bodies
Comply with inspections – Stop at mandatory boat inspection stations as part of B.C.’s Invasive Mussel Defence Program
Report sightings – If you spot zebra or quagga mussels, report them to the Province’s invasive species hotline (1-888-933-3722)
Stay informed – Follow local organizations like BCWF for updates and share information to raise awareness
Support conservation efforts – Get involved in local water monitoring and habitat restoration projects
Advocate for stronger protections – Contact your Member of Parliament and demand federal funding for invasive mussel surveillance be reinstated

Every action helps protect B.C.’s lakes, rivers, and local economies from invasive mussels.

Threatened Waters: What Invasive Mussels Mean for B.C.

Looking to learn more about the dangers of invasive mussels and what’s at stake for B.C.’s freshwater ecosystems? Watch this webinar recording featuring James Littley from the Okanagan Basin Water Board (OBWB) as he discusses the growing threat to B.C.’s lakes and rivers.