All over the shores of California, Olympia Oysters are the current only native oyster. Decades ago, they were found in abundance in bays and played critical roles in maintaining healthy aquatic ecosystems. However, a shift began in the 20th century as bays began to rapidly develop, there began to be less substrate for the Olys to colonize and thrive. Having a decreasing trend, Oly's work of filtering and cleaning water as well as protecting shorelines diminished.
Locally, the San Diego Bay Native Shoreline Project is actively fighting the historical loss of the 84% of local intertidal mudflats by installing artificial “reef balls” and “oyster castles.” Currently, their project is right on San Diego Bay, covering 10 acres; their pilot project is only covering 0.2 acres but efforts in the area are expected to enhance habitat beyond the area. The Bay was once dominated by shallow waters, intertidal mudflats, and the native Olumpia oyster reefs, but dredging, channelization, and shoreline armonning have eliminated much of this habitat, significantly reducing natural shoreline protection. Native Olympia oyster populations began to decline in the early 1900s because of overharvesting, wetland loss, and degradation of hard surfaces that are critical for reef growth.
The San Diego Bay Native Oyster Living Shoreline Project is actively seeking to restore a biologically rich native oyster reef that functions as an invisible part of the environment, ensuring a rich ecosystem in the marsh area.
Working on restoring these, the Coastal Conservancy and parents are taking active efforts along different Bays to obtain the positive impacts of Olys populations. “Innovative projects are installing and monitoring reef elements made of cement and oyster shell to test different siting, elevations, materials, oyster reef types, and different combinations of habitat elements to foster Oly population growth,” according to the California State Coastal Conservancy.
Works Cited
“San Diego Bay Native Oyster Living Shoreline.” Southern California Wetlands Recovery Project, https://scwrp.org/projects/san-diego-bay-native-oyster-living-shoreline/. Accessed 22 July 2026.
“Oly.” California State Coastal Conservancy, https://scc.ca.gov/oly/. Accessed 22 July 2026.