Zebra and Quagga Mussels

Identification & Biology
Latin Name : Dreissena spp.
Category : Other
Description :

Zebra and Quagga Mussels are small, freshwater mollusks. Distinguishing features of Zebra and Quagga Mussels:

  • Small, only up to 3 cm / 1 inch
  • Form dense clumps attached to hard surfaces
  • Propeller blade shaped
  • Zebra stripes often but not always present Native mussels and clams do not form clumps or attach to vertical surfaces. They are:
  • Far larger than zebra and quagga mussels; most adults are >3 cm/1 inch
  • Either oval or heart shaped
  • Buried, partially buried or on soft substrate or between cobbles

Mussel larvae swim in the water until three weeks of age. 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 several weeks without being immersed in water if they are left in a cool and moist environment, so mussels attached to boats or equipment can be transferred from one body of water to another.

Habitat

Invasive mussels are not known to occur in British Columbia. Zebra and quagga mussels live in freshwater lakes where they attach to a solid surface. Zebra mussels occur at lake depths of 1-30 m, but are rarely found below 15 m while quagga mussels occur at lake depths of 1-130 m, but are commonly found down to 30 m.

Impact & Risks

Quagga and zebra 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. To date, there has been no reported introduction of live quagga or zebra mussels into B.C. lakes or waterways. In 2013, Zebra Mussels were discovered in Lake Winnipeg, Manitoba and in 2016 they were found in Montana. Zebra and quagga mussels are not established in British Columbia, Alberta, Saskatchewan, Oregon, Idaho or Washington.

Prevention & Mitigation

The most effective way to ensure our lakes do not become infested with invasive mussels is prevention.

  • 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, live well 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).

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.