Quagga mussel (Dreissena bugensis)

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AIS Aquatic invasive species

Classification: Prohibited
Invasive species family: Dreissenidae
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Category: Molluscs
Family: Dreissenidae

September 2023: Invasive quagga mussels detected in Idaho; monitoring and prevention efforts ramp up in Washington

Potential risks

Where introduced to a water body, Quagga mussels threaten native fish and wildlife by consuming available food and smothering native species. They clog power plant and other water intakes, costing taxpayers millions of dollars.

Invasive species information

Invasive species additional information

Management strategy

WDFW has initiated volunteer monitoring programs in several lakes and along the Columbia and Snake rivers, and requires that out of state participants in fishing contests undergo boat inspections. Washington State Patrol Commercial Vehicle Inspectors check some of the boats that are commercially hauled into the state at the ports of entry, but not all haulers are required to stop. WDFW is increasing boater education efforts, and inspections of privately hauled recreational boats being transported from out of state.

Description and Range

Physical description

The Quagga mussel is usually light tan to almost white, with narrow strips. It is fan-shaped and rounded. Quagga mussels feed year around. This species can tolerate a wide range of temperatures and water depths as well as survive in brackish water.

Because the mussels can live out of water for up to a month if they are not subjected to heat or extreme drying conditions they may be easily transported on recreational boats. They can be on aquatic plants attached to boats or trailers, or as microscopic larvae in bilges, live wells, motor cooling systems and other water systems, or attached to the hulls, especially around trim tabs, transducers, keels or propellers.

Geographic range

Quagga mussels are native to the Caspian Sea and were introduced into the Great Lakes in the mid 1980’s in ships ballast water. Quagga mussels have since spread to more than 15 states.

For many years, the quagga mussel was not found in any inland lakes, possibly because they tend to inhabit deeper waters. However, the quagga mussel has found it’s way to Lake Mead, near Boulder City, Nevada, and in Lake Havasu and Lake Mohave on the California/Arizona border.