The San Francisco Bay Once Teemed With Oysters. What Happened?

Oysters are a controversial food.

Some people slurp them down by the dozen, while others would rather go hungry for days than be forced to eat a single slimy specimen.

As one KQED staffer put it: “No matter how fresh they are, no matter where they come from, no matter what is put on them, it reminds me of being congested and having snot just slide down my throat.”

Bay Curious listener Joseph Fletcher falls into the first category: The San Francisco resident loves oysters and has been wondering if he’ll ever get the chance to eat one grown in San Francisco Bay.

“Will oysters ever make a comeback in the bay and return to the numbers they had back in the days before the Gold Rush?” Fletcher wanted to know.

Introducing the Bay’s Native Oyster

There’s one type of oyster that’s indigenous to the San Francisco Bay, and that’s the Olympia oyster (Ostrea lurida). It’s named after Olympia, Washington, though these small, tangy oysters can be found up and down the west coast from Alaska all the way down into central Mexico.

Olympias — or Olys for short — can still be found in the San Francisco Bay today. But scientists say pollution from agricultural runoff is too high for commercial fishing. So instead, Olys sold in local restaurants and markets around here likely come from places farther afield, like Washington state.

For thousands of years, Olys grew in the San Francisco Bay in vast numbers. The shellmounds that can still be found in the East Bay are a testament to the importance of oysters and other shellfish in the diets of local tribes.

“They would be eaten raw. They would also be cooked in earth ovens underneath the ground and eaten with sea lettuces and different types of seaweed, acorn soup,” said East Bay Ohlone chef and food activist Vincent Medina. Medina is the co-founder of mak-‘amham and Cafe Ohlone (temporarily closed), a local cultural organization and restaurant dedicated to preserving and promoting Native American culinary traditions.

“Three generations back our family last were gathering oysters from the bay shore,” Medina said.

Oyster-Guzzling Settlers

The settlers who came to the Bay Area hungry for gold in the 1800s were also hungry for oysters. They foraged aggressively for whatever the bay had to offer — oysters, crabs and clams.

There are differing opinions on just how plentiful the San Francisco Bay oyster population was when the Gold Rush began.  Environmental historian Matthew Booker, who has written a book all about the bay’s oyster-ful past, takes the more conservative view. He argues that by the 1840s, the Oly population had likely dwindled owing to thousands of years of slow sea level rise and melting Sierra glaciers that muddied the bay and destroyed the Olys native habitat.

“We know that native oysters existed in San Francisco Bay in the 1840s and they still exist today,” he said. “But I have not found evidence that they existed in large enough numbers to support any fishery at all.”

Booker said it didn’t take long for local native oyster supplies to run out. So the oyster-guzzling gold miners were forced to look farther afield.

“All of the estuaries of the west coast are essentially mined for their oysters to satisfy this endless demand from San Francisco,” said Booker. “The most famous is Willapa Bay (in Washington state), which shipped huge numbers of oysters to San Francisco Bay before collapsing from over-harvesting in the late 19th century.”

Importing East Coast Oysters

Booker said the trade was unsustainable and essentially mined the wild native population until it disappeared. So entrepreneurs took to importing non-native varieties from the east coast.

“You could capture baby oysters, barrel them up, put them on board schooners, and later on board unrefrigerated train cars, and ship them across the entire United States,” Booker said. “And then they would be placed into San Francisco Bay on privately owned tidelands and harvested as a crop.”

Demand for oysters at this point was so high, pirates frequently raided the oyster beds. Bay Area author and erstwhile oyster pirate Jack London glamorized the experience of stealing oysters from the San Francisco Bay by night and selling them in the Oakland markets the next morning in several of his literary works, including the autobiographical novel “John Barleycorn.”

“The winds of adventure blew the oyster pirate sloops up and down San Francisco Bay, from raided oyster-beds and fights at night on shoal and flat, to markets in the morning against city wharves, where peddlers and saloon-keepers came down to buy. Every raid on an oyster-bed was a felony. The penalty was State imprisonment, the stripes and the lockstep. And what of that? The men in stripes worked a shorter day than I at my machine. And there was vastly more romance in being an oyster pirate or a convict than in being a machine slave. And behind it all, behind all of me with youth abubble, whispered Romance, Adventure.”

But even the imported oysters didn’t survive in San Francisco Bay for long.

Hydraulic mining in the Sierra Nevada during the Gold Rush years churned up mud and sand that swept downriver to San Francisco Bay.

Booker said growers moved their Atlantic oysters to the South Bay where mud was less of a problem. But the pollution in the bay from industry and human sewage worsened as the population grew and established itself. A rash of deaths connected to eating contaminated oysters put an end to the San Francisco Bay oyster industry.

“By the early 20th century, there are plenty of oysters in the bay,” Booker said. “But the people eating them are no longer so sure if this is the right food.”

In the 1930s, oyster farming resumed in the cleaner waters of Drakes Bay and Tomales Bay north of San Francisco. But the focus, especially after World War II, was on Pacific oyster varieties from Japan — like the Miyagis and Kumamotos that are still popular here to this day. Interest in cultivating the native Olympia oyster as a food source dwindled.

It still hasn’t really come back.

Bringing Olys Back

It’s hard to find Olympia oysters in restaurants and seafood markets in the Bay Area. The Hog Island Oyster Company at the San Francisco Ferry Building is one of few Bay Area retailers that sells them to the public.

Hog Island started cultivating small amounts of the native Olys at the company’s facility in Tomales Bay. But the process is far from easy.

“Olympias are very slow growing,” said Hog Island Oyster Company founder and CEO John Finger. “They only seem to have a really good bigger spawn every three to four years. That’s problematic, because if you have a bad year and you’re not going to have another spawn for three or four years, it really makes it hard to get the population to some sort of critical mass.”

On top of this, Finger said the Olys’ small size means they’re difficult to shuck. And their intense, coppery flavor makes them a bit of an acquired taste. “But certain people know them and appreciate them,” he said.

In other words, Olys are definitely not a big seller. But reviving these indigenous oysters as a source of food isn’t a major priority for Finger. He’s among a growing number of Bay Area producers, scientists and community activists interested in bringing them back to the bay in large numbers for an entirely different reason — environmental conservation.

“Can we improve the overall habitat quality for all creatures in San Francisco Bay?” Finger said. “And one of the ways that people think they can do that is by creating more oyster reefs.”

One local nonprofit community group that’s working towards this goal is the Wild Oyster Project.

“Oysters have superpowers!” said Linda Hunter, founder and director of the Wild Oyster Project. “They have so many wonderful benefits.”

Oysters help maintain the balance of a marine ecosystem by reducing excess algae and sediment that can contribute to low oxygen levels, causing other marine life to die.

“One grown oyster can filter 50 gallons of water a day,” Hunter said.

Oysters cluster on discarded shells, rocks, piers and other hard, submerged surfaces. They fuse together as they grow, forming rock-like reefs that make ideal homes for other marine animals and plants. “Oysters provide habitat for other critters,” Hunter said.

Oyster reefs also protect coastal lands by reducing the impact of storm waves. “It’s been proven that oyster reefs attenuate the effects of rising tides caused by climate change,” Hunter said.

Building Oyster Reefs

Bay Natives is one of several local businesses the Wild Oyster Project partners with around the Bay Area. The nonprofit collects discarded oyster shells from local restaurants and piles them up at partner sites to dry out over several years.

Hunter said eventually the shells will be built into oyster reefs and placed in the bay. The idea is for these reefs to attract native oysters, and, as a result, other wildlife — like eelgrass, salmon, crabs and egrets.

Hunter said her group has installed — or is working on installing — reefs at several locations including Alameda and Point Pinole in Richmond. She said even skeptics are starting to see the benefits of restoring oyster populations.

“The first oyster reef we built at Point Pinole, I got a phone call from a fisherman who was complaining that his fishing line had been snagged on one of our reef balls,” said Hunter. “And I said, ‘Hmm, have you noticed more fish?’ And he said, ‘Yes, I have! Thank you very much.’ ”

The Future of Oysters in the San Francisco Bay

Even though scientific research teams, oyster farms and community groups are working hard to reinvigorate the bay, it’s an uphill struggle.

“We’re so far below where we were historically,” said Ted Grosholz, an ecologist at UC Davis who studies marine biodiversity. “As long as we sort of just increase the populations, we’re moving in the right direction.”

The issue is climate change.

Grosholz said rising air temperatures, especially in the warmer months, can be fatal to oysters exposed on reefs for hours at a time. He’s also worried about the heavy rainfalls we’ve been getting on and off in recent years. Rain increases the runoff from rivers into the bay and lowers the salinity to levels that kill oysters.

“We lost basically every oyster in the place two years ago to that big, huge rain and the atmospheric rivers that came along with it,” Grosholz said.

But he said it’s important to continue the work of restoring oyster populations, even if it’s slow-going. It could be several decades before the natural filtering system that comes with a healthy bay ecosystem has sufficiently cleaned out lingering pollutants. He estimates it will be at least 50 years before people can eat oysters out of the San Francisco Bay safely again.

“Just remember that this oyster restoration is part of a living shoreline,” he said. “It’s not just restoring one species. It’s restoring all the species that oysters support.”