Oysters

Crassostrea gigas, Crassostrea sikamea, Crassostrea virginica, Ostrea edulis

Illustration of oysters growing on mudflat, by Tom Crestodina

Farmed

Gear

Suspended Longline Culture

Broadcast Bottom Culture

Off-Bottom Bag and Stake Culture

Location(s)

With the decline of the native Olympia oyster (Ostrea lurida) in the late 1800s and a growing demand for oysters for food, non-native species of oysters were introduced to the West Coast. First came the Eastern oyster (Crassostrea virginica) from the East Coast of the U.S. in the 1890s. Soon after, the Pacific oyster (Crassostrea gigas) was introduced from Japan and gained a strong foothold in Washington during the 1920s. Other species have since been introduced and grown, including the Japanese Kumamoto oyster (Crassostrea sikamea) and the European flat oyster (Ostrea edulis).

Oysters are bivalves, meaning that they have two shells connected by a hinged joint. Their whitish-gray shells are highly calcified and irregular in shape. Oysters secrete a type of natural "glue" in order to attach to surfaces. They generally settle in areas where there are already large aggregations of both living and dead oysters, creating large "reefs" of accumulated shells. Like coral skeletons, oyster shells are made up of calcium carbonate, which is why both create “reef-like” structures. Oysters feed by filtering microscopic plankton and small floating material from seawater.

Overall availability

While Washington is the largest producer of cultivated (native and non-native) oysters in the U.S., oysters are also produced in Oregon and California. Commercially grown oysters are available year-round in a variety of product forms including live, fresh, frozen, canned or smoked. They can be purchased at fish markets, grocery stores, or directly from oyster farms.

activity wheel for oysters that depicts monthly activity levels (peak, low, closed)

Management

Oysters are farmed using a variety of off-bottom methods: bag (basket) culture (flip bags, tumble cages, and rack and bags) and longline, or simply grown in the ground in a method known as broadcast on bottom culture.

Commercial shellfish aquaculture is managed by a variety of agencies such as the state Departments of Fish and Wildlife or Natural Resources (CA, OR, WA), the Army Corp of Engineers, the Food and Drug Administration, and local and state Departments of Public Health. In Washington, shellfish aquaculture is also co-managed with Treaty Tribes. Learn more about commercial shellfish aquaculture.