Email
PrintShell Game
Building homes for oysters in San Francisco Bay
Biologist Rena Obernolte and education coordinator Andy LaBar of The Watershed Project use the half-shell remains of restaurant oysters to build reefs for native bay oysters.
Photograph by Ann Marie Brown
On a rainy day in January, a handful of volunteers gathered on the edge of San Francisco Bay to build homes for a remnant population of native oysters that thrive below the chilly water’s surface. Clad in Gore-Tex and boots, the group transferred large sacks of empty oyster shells, donated from a local restaurant, into sturdier mesh bags and stacked them on wood pallets. The pallets would later be submerged along the muddy shores just west of the Richmond-San Rafael Bridge.
“The empty shells serve as a nursery for young oysters,” says marine biologist Dr. Bud Abbott. “Oysters can only thrive if they can find suitable structures on which to attach. Most of the structures that were originally in the bay were removed because they were hazards to navigation. So our question became, how can we efficiently put structures in the bay that oysters can settle on?”
This San Rafael restoration site, on private land belonging to the Marin Rod and Gun Club, is one of several throughout the Bay Area, including sites in Mountain View and Redwood City, and soon, in the Berkeley Marina. They are part of a pilot project for the Oyster Habitat Stewardship and Restoration Program, a joint partnership of the East Bay nonprofit The Watershed Project and a handful of biologists who are restoring sub-tidal habitat in San Francisco Bay.
“San Francisco Bay was once filled with oysters,” says Dr. Juliana Gonzalez of The Watershed Project. “They were an important food source for the Native Americans and were plentiful in the bay right up until the Gold Rush. In the South Bay, there were so many oysters that the beaches were white from their crushed shells.”
Both Gonzalez and Abbott believe that a thriving oyster population is vital for the health of the bay.
“Oysters suck in water, and filter and clarify it. They keep the water clear of sediments, which allows sunlight to penetrate and species like native eelgrass to grow. Eelgrass is protective habitat for small fish. It’s where herring lay their eggs. Small fish encourage the presence of larger fish—salmon, sturgeon, steelhead, and striped bass among them—which will come to feed,” says Abbott.
“Oyster reefs create what we call keystone habitat, which helps a lot of different kinds of organisms, not just oysters. Oysters are at the start of a chain that ultimately leads to a healthy ecosystem.”
Unlike typical restaurant oysters, which have shells up to six inches long, the native bay oysters are smaller Olympias, which grow to about the size of a half-dollar. Olympia oysters were once plentiful in sub-tidal regions from Southern California to southeastern Alaska. Although other types are commercially farmed in places like Tomales Bay and Point Reyes in western Marin County, the Olympia is the only native California oyster.
On many days, the volunteers at the oyster restoration sites are schoolchildren from Marin and San Francisco counties. As part of the outdoor learning component of their curriculum, the students collect and analyze data from the oyster restoration sites. In the process, they learn about the biology and ecology of oysters, salmon, herring, and eelgrass.
“We’re interested in having students understand the connection between healthy watersheds, a healthy bay, and healthy oceans,” says Linda Hunter, executive director of The Watershed Project.
To volunteer to help with oyster restoration in San Francisco Bay, contact The Watershed Project at 510.665.3430 or thewatershedproject.org.
