Bringing Oysters Back to the Bay

Sean Greene

Christopher Lim, right, shows Ashlee Johnson a rock covered in San Francisco Bay’s only native oyster, the Olympia. Both work for the Richmond-based environmental nonprofit, The Watershed Project, which is working to restore Olympia habitat along the Point Pinole Regional Shoreline.

During the Gold Rush, the San Francisco Bay’s native oyster habitat was all but wiped out due to overharvesting and hydraulic mining washing sediment onto the bay floor. But a Richmond-based nonprofit has plans to restore the shellfish’s lost habitat along the Point Pinole shoreline.

Point Pinole has been a hotspot for oysters over the past couple summers, said Christopher Lim, Living Shoreline Program manager at The Watershed Project, making it an ideal target for restoration.
“Oysters, I think, definitely have that connection to people whether it’s through food … (or) the history of oysters in San Francisco Bay,” Lim said. “Part of the reason we would like to restore oysters is because we know of their ecosystem benefits in the Bay, and they were probably here in much greater numbers in the past.”
But how will the native Olympia oyster will respond to the stressors caused by climate change? Several environmental groups, including The Watershed Project, are working with scientists at the National Estuarine Research Reserve System to answer this question.
On Tuesday, Lim was out at Point Pinole Regional Shoreline, counting young oysters on tiles placed in the water and along a transect running parallel to the water line. Lim, with a staff member and a volunteer, recorded the  temperature and kinds of rocks around the oysters, took photographs of the tiles and boxed up others – all data they'll send back to NERR.
The study looks at factors such as salinity, dissolved oxygen, water and air temperature and sedimentation – all factors expected to change with climate change – and their effect on oysters. The conclusions from their field monitoring and lab experiments will inform current and future habitat restoration efforts.
“It’s a real good team that they’re able to do (the really hardcore science) … but then we’re able to as the nonprofit as The Watershed Project talk to the community and tell them about how climate change and how it’s going to affect the wildlife in the Bay and eventually the people too.”
NERR is monitoring Olympia populations in sites around the Bay and Elkhorn Slough with the help of groups like The Watershed Project, Richardson Bay Audubon and the Living Shorelines Project.
“Those groups are the people who will use our tools in the end,” said Anna Deck of San Francisco NERR. “So part of working with them … is to keep in close touch with the people that will use our end results.”
In the meantime, The Watershed Project’s restoration effort is moving forward.
This week the group plans to start building 100 concrete oyster reefballs to sink in the Bay. The group’s data shows plenty of oyster “recruitment,” or spawning, at Point Pinole, so the nonprofit expects baby oysters to latch to their artificial reefs, made from dredged bay sand, concrete and oyster shells.
Oysters benefit the ecosystem in a number of ways.
The filter feeders protect water quality and could promote underwater plant life. The reefballs themselves should also become habitat for worms, crabs and fish. And that becomes food for bigger fish and birds.
Olympias, the only oyster species native to the Bay, are smaller – around two inches long – than the larger and more fast-growing Pacific you probably ordered at a restaurant. Lim said he enjoys the taste of Olympia oysters, but he makes one thing clear.
“The oysters that we’re researching here … we’re not meaning for them to be eaten,” he said. “We’re doing it for the ecosystem benefits that oysters bring to the shoreline and to the subtidal habitat.”
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