As the oceans acidify, these oyster farmers are fighting back

When visitors to Hog Island Oyster Co. shuck Pacific oysters at picnic tables overlooking Tomales Bay, it’s the final stage in a story that founding partner Terry Sawyer likes to tell about the shellfish, the bay, and all the steps that went into bringing the briny delicacies to the plate just a few hundred meters from where they were harvested.

It’s a story that now also touches on the carbon cycle, climate change, and the ways in which the very chemistry of the ocean is shifting and how small businesses like Hog Island – along with the entire ocean ecosystem – are struggling to adapt. 

The oyster farm helps make abstract issues like ocean acidification and climate change concrete, says Tessa Hill, a marine scientist at the University of California in Davis who studies acidification and has developed a partnership with Mr. Sawyer and Hog Island. “It feels incredibly tangible,” she says. “It’s about the food on our plate; it’s about family businesses; it’s about people’s livelihood along the coast. Ocean acidification and climate change will fundamentally change our relationship with the ocean.”   

‘A giant sponge’

Ocean acidification is a direct result of increased carbon dioxide emissions. The oceans – “a giant sponge,” as Professor Hill likes to explain it – absorb about 30% of the carbon dioxide humanity emits. As those levels rise, the chemistry of the ocean fundamentally changes, measurably lowering the pH and making it more acidic. For sea life, one of the biggest risks is to creatures – like shellfish, corals, and sea urchins – that need carbonate ions to build their shells or other structures. The shifting chemistry of the ocean makes those key building blocks scarcer.

The problem has only begun to get significant attention in recent decades. At this point, the average pH of the surface ocean has dropped by 0.1 pH units since preindustrial times, amounting to about a 28% increase in the acidity of the oceans overall, says Richard Feely, a senior scientist at the Pacific Marine Environmental Laboratory at the National Oceanic and Atmospheric Administration (NOAA).

But he notes that that change is distributed unevenly geographically, with more of the pH changes seen farther away from the equator. On the Pacific coast of the United States, meanwhile, the changes are most acute because the decreasing of the pH at the surface is combined with upwelling of carbon dioxide-rich waters from below. 

“We’re seeing pH values here that you might see at the end of the century elsewhere,” says Dr. Feely. “We’re seeing it first here, and we’re also seeing the biological impacts of acidification first here.” Pteropods, for instance – tiny sea snails which play a critical role in ocean food chains – have been dissolving in some of those acidic waters.

Mr. Sawyer and his partners at Hog Island Oyster Co. first started seeing indicators of problems with acidification more than a decade ago, though they didn’t yet know that was the problem. 

At the time, they were buying all their oysters as “seeds,” at about a quarter-inch size. For the first time, they started having trouble with oyster seeds not being available. He and others in the industry started realizing the oyster crashes were coinciding with upwelling and high acidification events, and acidification became a hot topic for the industry.

For Hog Island, it’s meant some changes, including investing in a hatchery of its own and even starting to experiment with different brood stock to find a strain more resistant to acidification. The farm is also looking to natural buffering solutions, like growing edible seaweed along with the oysters.

And it's led to a partnership between Hog Island and Professor Hill and the Bodega Marine Laboratory where she works. Together, they started monitoring the waters of Tomales Bay, first with rudimentary equipment that was checked monthly and now with monitors provided by NOAA that give real-time data on temperature, salinity, carbon dioxide, and other metrics.

That data, says Mr. Sawyer, translates to “how hard an organism is working to build a shell.” 

“We need resiliency,” says Mr. Sawyer. “We’ve done diversification vertically and horizontally. … What you need to do from a resiliency point of view, for any farming, is have the ability to try new methods, new gear, different zones within the tidal range, or different species.”

‘Corrosive water’

Some of the ongoing research is also helping with projections and with mapping out the changes along the West coast – data that could help Hog Island and other oyster companies make decisions about where to place future farms or hatcheries and can help state agencies making decisions about various native species.

From Professor Hill’s perspective, the partnership has given her and other researchers more data and monitoring – a critical piece of understanding how ocean acidification is playing out – as well as a concrete way to talk to people about ocean acidification and how climate change is impacting them. She and Mr. Sawyer have talked to key policymakers, legislators, and regulators in both Sacramento and Washington about the issues.

Earlier this month, the U.S. House of Representatives for the first time passed several bipartisan ocean acidification bills. The four bills, which now move to the Senate, authorize more coastal and ocean monitoring, research on the impacts of acidification on coastal communities and estuaries, prizes for scientists who come up with innovative approaches to ocean acidification, and the creation of a new ocean acidification advisory board.

It’s a good first step, says Professor Hill, noting that that monitoring, along with investment in trying to understand adaptation and mitigation, is really important. “But what we’ll need is large scale government action,” she says.

Mr. Sawyer, sitting next to her outside the oyster company by the salt marshes and mudflats of Tomales Bay, is more blunt: “We need a paradigm shift,” he says. “What’s really striking is the difference between the rate of change [in the ocean] and the rate of the ability to change and the resiliency on the policy side. It’s diametrically opposed.”

While Hog Island is finding ways to adapt to current and future ocean acidification, there are tougher questions on the horizon for native shellfish and pteropods. Currently, intense acidification events have been limited to a few weeks of the year and haven’t been a major threat for the Olympia oysters that are native to Tomales Bay, a 12-mile-long narrow estuary that stretches southeast from the Pacific along the San Andreas Fault. Low salinity, stemming from big winter rain events, and invasive snails that prey on the oysters have been bigger problems for those oysters.

“But lab experiments we have done show that every year that goes on, [ocean acidification] will be a bigger and bigger issue for native oysters,” says Professor Hill. Ecologists active in restoring native species – oysters, abalone, coral reefs – need to start looking ahead as they do restoration work, she says. “The way that things have been for the past 10 years is not that relevant. We have to think of the ocean that we have to face in 50 years. We have to be restoring species to survive that condition.”

“Right now during the spring, you have pockets along the coast that are corrosive enough that it’s very hard for anything with a shell to make a shell,” she says. “By 2050, half of the year will be those conditions everywhere along the coast. It will be a blanket of corrosive water.”

One of the public faces of Hog Island, Mr. Sawyer is bearded and loquacious, a former aquarium keeper at the Monterey Bay Aquarium who loves surfing, diving, and paddleboarding and relishes his current lifestyle, living just nine miles from the oyster company in what he calls “paradise.”

“We’re not a huge company, but we’re known for activism,” says Mr. Sawyer of his business that has grown from three partners to almost 300 employees and includes restaurants in Napa and San Francisco.

“You can have somebody come here, whatever level of connection they have to the issue … and you can connect them to the food and you get the full sensory – the visual, the smells, the taste, everything. Then they can tie that to the issues,” he says. “You can get through to people through their stomachs.”