Zebra Mussels

Zebra Mussels
Sea Grant Michigan Photo

Zebra mussels were found in San Justo Reservoir, in San Benito County, in January of 2008. This is the first population of this invasive species to be found in California waters.

Zebra Mussels (Dreissena polymorpha) are a small freshwater mollusk originating from the Balkans, Poland and the former Soviet Union (National Atlas). It was first detected in the U.S.in 1988 in the Great Lakes. They were probably picked up from freshwater European ports in the ballast water of ships. Zebra mussels get their name from the striped pattern on their shells. They are a threat to the environment because the mussels can colonize over other species shells which prevents the shells from opening and not allowing feeding of the infested organism. Similar to the quagga mussels, zebra mussels are also pose concerns for municipal water facilities. They can potentially colonize water intake pipes and restrict water flow (U.S.G.S. Nonindigenous Aquatic Species).

The mussels can grow to a length of about 2 inches. There life span is recorded at 4 to 5 years and they reside in fresh water at depths from 6 to 24 feet. Adult female mussels can produce between 30,000 to 40,000 eggs per year (USGS). However, only two percent of zebra mussels live to adulthood (Sea Grant Michigan).

Zebra mussels are native to the Black, Caspian, and Azov Seas.

Zebra Mussel Links

California Department of Fish and Game News Releases:

Zebra Mussels Found in California Reservoir (Jan. 16, 2008)

U.S. Army Corps of Engineers Zebra Mussel Research Program

U.S. Army Corps of Engineers Zebra Mussel Information System

U.S. Geological Survey Zebra Mussel Program

National Atlas

U.S.G.S. Nonindigenous Aquatic Species

Sea Grant Michigan Quagga Mussel