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Earth Island Reports

Saving Oysters to Save Ourselves

The Wild Oyster Project

Oysters were once ubiquitous in San Francisco Bay. They were a dietary mainstay for locals, from members of the Indigenous Ohlone Tribe, who left copious middens of shells around the Bay, to the gold miners, who raved about the native Olympia oysters (Ostrea lurida/conchaphila) or “Olys.”

As a 1909 San Francisco Sun article put it: “The oyster of San Francisco is famous. Its celebrity has gone forth to the ends of the earth, carried by the eloquent tongues of the gourmand, native or visitor, who has tasted, smacked his lips, tasted again, and instantly has become the willing slave to the appetite for the delicious bivalve that thrives upon the oyster beds of San Francisco Bay.”

photo of a hand, holding an oyster Native Olympia oyster habitat is in short supply in California.

It is estimated that native oyster beds once covered 100,000 acres of the Bay. During the California Gold Rush, unsustainable harvests devastated the population. Hydraulic gold mining compounded the harm, sending vast amounts of sediment from the Sierra into foothill watersheds that flooded the San Francisco Bay, smothering much of the subtidal ecosystem. Billions of oysters were buried alive, along with the substrate they need to survive. Almost overnight, water quality was ravaged by suspended sediment. Later industrial activities – filling, dredging, and channelization, to name a few – also left their mark on the native bivalves. Most of the oysters you find in California now are Pacific oysters (Crassostrea gigas), first introduced in the US from Japan in the early 1900s for commercial harvesting.

Small remnants of our native Oly population still exist, but suitable habitat is in short supply. When oysters spawn, their larvae, swim around for a bit. They have tiny hair-like appendages, called cilia, that they flutter about, and a leg they use to attach to their future home, preferably another oyster shell. Unfortunately, there is almost no place for these young oysters to “hang their hat” in the Bay. A personal ad for SF oysters might read “Oysters, Desperately Seeking Other Oysters.”

People around the world are beginning to understand what invaluable creatures these bivalves are, as well as the huge contribution they make to healthy estuaries. Oysters are adept ecosystem engineers. Attaching their body to the backs of their ancestors, they build reefs that provide habitat for many other species and help protect the land from the worst impacts of storm surges. Not to mention that oysters help improve water quality: A single oyster can filter 50 gallons of water a day!

Learn more about this Earth Island Institute project at: wildoysters.org

Water quality, though not perfect, has improved since the Gold Rush years. And over the last two decades, researchers have been experimenting with ways to reintroduce substrate into the Bay to see if, where, how, and how well native oysters would take to it. Now the results are in: Their research has demonstrated beyond a doubt that if suitable substrate is provided, oysters will self-recruit and settle on it. Better still, the chances of restoration success are now increased because, as sediment continues to clear out of the Bay, hard substrate – required for Olympia oysters – will be “cleaner,” meaning there will be more attachment sites.

That’s where The Wild Oyster Project comes in, engaging communities in the movement to give struggling Olys a hand and paving the way for an Olympia oyster comeback.

Every oyster restoration project requires oyster shell as its building blocks. Our Save Your Shucks! program encourages volunteers to collect discarded shell from restaurants and cure them for up to a year. With these cured shells, volunteers then help deploy oyster recruitment tools like oyster reefs and gardens at sites around the Bay. They also act as citizen scientists, monitoring how many baby oysters are enticed by the new substrate.

Native oyster restoration in the Bay is on the cusp of moving from the hands of restoration scientists to the larger community. Our program is a bridge between the two. When we share the reasons for “why” we work to restore native oysters, many people have an “a-ha” moment and the bigger picture comes into focus: Native oyster restoration not only benefits the Bay ecosystem, but also the people who call the Bay Area home.

   

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