Olympia Oyster
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Scientific Name Ostreola conchaphila
Conservation Status Threatened
Family Bivalve
Habitat West Coast shores
Food Plankton and small particles

The Olympia oyster, Ostreola conchaphila, is the native oyster of the Pacific coast of North America from Alaska to Mexico. The name is derived from the important 19th century oyster industry near Olympia, Washington, in Puget Sound.

Native American peoples consumed O. conchaphila everywhere it was found, with consumption in San Francisco Bay so intense that enormous middens of oyster shells were piled over thousands of years. One of the largest such mounds, the Emeryville Shellmound, near the mouth of Temescal Creek and the eastern end of the San Francisco – Oakland Bay Bridge, is now buried under the Bay Street shopping center.

O. conchaphila nearly disappeared from San Francisco Bay following overharvest during the California Gold Rush (1848-50s) and massive silting from hydraulic mining in California's Sierra Nevada (1850s-1880s). California's most valuable fishery from the 1880s-1910s was based on imported Atlantic oysters, not the absent native. But in the 1990s, O. conchaphila once again appeared in San Francisco Bay, surprisingly in some of the most polluted waters of the bay near the Chevron Richmond Refinery in Richmond, California.

Species restoration projects for the Olympia oyster funded by the U.S. Government are active in Puget Sound and San Francisco Bay. An active restoration project is taking place in Liberty Bay, Washington. This Puget Sound location is the home of an old and new Olympia oyster population. The re-establishment of the population is currently threatened by the invasive Japanese oyster drill Ocinabrina inorata. This species preys on the oysters by drilling a hole between the two valves and digesting the oyster's tissues. O. inornata is a threat to the oyster especially in areas with low populations of the mussel Mytilis.

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