Zebra and Quagga Mussels

Identification & Biology
Latin Name : Dreissena spp.
Category : Other
Description :
  • Small, freshwater mollusks (3 cm / 1 inch)  
  • Form dense clusters attached to hard surfaces  
  • Propeller blade shaped  
  • Stripes often present but not always   


Mussel larvae float in the water until three weeks of age. They then begin to settle out of the water under the weight of their forming shells and attach to hard surfaces. As adults, these small, freshwater mussels can easily attach themselves to boat hulls, trailers, motors, equipment, vegetation and other organisms. They multiply rapidly and are extremely difficult to eradicate once they become established in an area. In larger water bodies and complex ecosystems, they may be impossible to eradicate unless detected and contained before they become established. Zebra and quagga mussels can survive for up to 30 days without being immersed in water if they are left in a cool and moist environment, therefore mussels attached to boats or equipment can be transferred from one body of water to another.  

Zebra and Quagga mussels can sometimes be confused with native mussels. Native mussels do not form clumps or attach to vertical surfaces, are far larger (>3cm), oval or heart shaped, and buried or partially buried in soft substrate or between cobbles. 

Look Alikes

Zebra and quagga mussels live in freshwater lakes where they attach to hard surfaces. Zebra mussels commonly occur at lake depths of up to 15 m, while quagga mussels commonly occur at lake depths of up to 30 m. Currently, zebra and quagga mussels are not known to be in BC.

Impact & Risks
  • Zebra and quagga mussels pose a serious threat to B.C.’s aquatic ecosystems, salmon populations, hydro power stations and other infrastructure facilities. 
  • They can clog pipes (increasing maintenance costs for hydroelectric, industrial, agricultural and recreational facilities), cause ecological and economic damage, displace native aquatic plants and wildlife, degrade the environment and affect drinking water quality. 
  • The economic impact of these invasive mussels to hydropower, agricultural irrigation, municipal water supplies, recreational boating, fisheries and tourism has been estimated to be $45 million per year in the Okanagan. 
Prevention & Mitigation
  • CLEAN off any visible mussels, plants, mud or other debris from all equipment that enters the water (e.g. boats, trailers, waders, scuba gear) 
  • DRAIN all water from your bilge, ballast, livewells and bait buckets onto dry land 
  • DRY all equipment for 5 days in the sun before entering another water body. If this is not an option, then pressure wash all equipment with hot water (60 C) and towel dry. 
  • Report possible sightings of Zebra and Quagga Mussels to the B.C. Conservation Officer Service’s “Report All Poachers and Polluters” (RAPP) hotline: 1 877 952-7277 (toll-free). 
Treatment & Disposal


Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.