Oysters are big business. That might not be immediately apparent on a visit to Hog Island Oyster Company in Northern California’s bucolic Tomales Bay, where the place still has a seafood shack sensibility. The farm was started more than 30 years ago by two marine biologists who borrowed $500 from parents and a boat from neighbors and began cultivating briny bivalves in five-acres of intertidal waters.

As a small seafood business and sustainable farm, Hog Island has weathered its share of hardships, including significant oyster seed shortages and the threat of species extinction, courtesy of environmental challenges.

It has stayed afloat, though. In fact, three decades on, Hog Island has quite the cult following around the country and it has earned respect as a leader in the shellfish industry. These days, founders John Finger and Terry Sawyer preside over a $12 million operation that employs almost 200, farms 160 acres, and harvests over 3.5 million oysters, clams, and mussels every year.

In addition to the flagship farm, the company boasts an oyster bar in Napa (that survived the recent earthquake unscathed) and the recently expanded oyster bar in San Francisco’s Ferry Building, where prospective diners still wait an hour or more to snag a seat before they’re happily slurping salty, meaty morsels off the half shell. The beloved restaurant is now double its original size and features an updated, chef-driven menu and an au courant cocktail program. In the 10 years the oyster bar overlooking San Francisco Bay has been in business it’s shucked nearly 10 million oysters. At the current rate of demand, they expect to shuck 2 million oysters a year, says Finger.

The biggest threat to business? Not the new crop of oyster bars popping up around town and elsewhere in the nation. Nor is it keeping up with consumer demand—for now. No, Hog Island is dealing with a different kind of problem: A quandary known as ocean acidification or climate change’s caustic cousin. The company has been working with scientists to study the impact of this sea change in shellfish habitat that’s killing off billions of baby oysters in the Pacific Northwest and beyond. They’re also blazing a trail on the political outreach and public education front.

“We’re trying to quantify the problem in our collaborations with academics so that we can get policy makers to make the kinds of changes on the alternative energy front to address it,” says Sawyer, who believes America’s addiction to fossil fuels and their accompanying carbon dioxide emissions are at the root of the problem.

Ocean acidification is a big bummer for baby oysters. Here’s why: Much of the carbon dioxide released into the atmosphere is taken up by oceans, dramatically lowering pH levels in the process, and creating a chemical change that makes the ocean water more acidic. That increase in acidity creates a hostile habitat for oyster seeds (also called spat) and other marine life. Ocean acidification is especially harmful to oysters at their larval stage, when they’re building their protective coverings. Their fragile calcium carbonate shells don’t form well under increased acidic conditions, stunting their growth, making them more vulnerable to predators, and sometimes killing them outright. This sea shift can also stress small oysters, making them more susceptible to disease, says Sawyer.

The Hog Island team closely monitor changes in water temperature, salinity, oxygen, and pH at the farm and respond as needed. But that’s not enough. “It’s going to take a paradigm shift in behavior to address this,” says Sawyer. “We have no choice but to face it: We’re on the leading edge of what climate change and fossil fuels are doing to our waters.”

Oysters as Endangered Species?

Could the end of oysters be near? These veteran shellfish farmers aren’t prone to such histrionic proclamations. But they are concerned about supply and the farm is looking beyond science for solutions. It’s beginning to diversify, which as all farmers know, can be a saving grace during tough times.

Hog Island is expanding its aquaculture operation. It plans to open an oyster hatchery in Northern California’s Humboldt Bay that will provide seeds to grow in Tomales Bay; permits have been approved and baby bivalve cultivation is expected to start later this year. It’s a practical response to the Pacific Northwest’s spat shortage. Eventually, the site will harvest some of its own oysters as well and sell seeds to other oyster farmers.

“Running a hatchery is a tricky and expensive undertaking,” says Finger, who adds that the $1.5 million enterprise will take two years to complete. “We never thought we’d need to go into the hatchery business but the oyster seed shortage changed that.”

Hog island has also partnered with another shellfish farm in Discovery Bay, Washington, where it sources a popular Pacific oyster. The water at Discovery Bay offer a different marroir (think terroir, only the sea version) than Tomales Bay–it’s colder and more oceanic for starters. And, bonus, the oysters grown there, called Cliffsides, offer customers a more mineral-like taste than your typical Pacifics.

For geoduck clam farmers Peter and Robyn Downey of it’s a win-win. The Downeys were looking for a way to diversify their income and offer steadier work to their employees. And the Hog Island crew needed a reliable supplemental source of oysters. The nascent relationship has yielded around 400,000 oysters to date.

Hog Island does ship in oysters from Washington state and the East Coast to add variety, but it hasn’t had to import oysters in the past couple of years due to shortages, says Finger. Still, it has dramatically scaled back its wholesale business to high-end restaurants due to supply issues.

Hog Island is especially known for their extra-small Pacifics, dubbed Sweetwaters. Now, the oyster farm is working closely with conservation organizations to reestablish the Olympia, the only indigenous San Francisco oyster. A staple in the diet of coastal Native Americans, overharvesting, development, and pollution all but wiped out these tiny but mighty mollusks during and after the Gold Rush. Since then, these bivalves–known for their cucumber finish and slightly metallic taste–have been hard to find in local waters.

“Olympias offer a blast of copper on the palate but they’re difficult to grow and sensitive little guys,” says Sawyer. While it might be years before these gems are harvested for public consumption, the Hog Island farmers are committed to reestablishing a native species in a marine ecosystem.

A Big Hit on the Half Shell

Planned aquaculture farms like Hog Island have supplanted the wild oyster population for decades now and the tiny town of Marshall in Tomales Bay, home to Hog Island, is Northern California’s Oyster HQ, with five commercial oyster companies in the mix. Drakes Bay Oyster Company, which the company claims supplied around 40 percent of the state’s oysters, closed its retail operation and cannery in July following unsuccessful efforts to keep operating in the Point Reyes National Seashore after its 40-year lease with the National Park Service expired.

A major supplier to Bay Area restaurants, its unclear where chefs will source local oysters once the farm stops harvesting altogether. This summer, The Tomales Bay Oyster Company and several West Marin restaurants filed a lawsuit to prevent the closure. Just yesterday, a federal judge rejected their efforts.

John Finger would like to see new oyster farms established, but says the expense and bureaucracy is a major impediment in California. “It can take two years and $200,000 just to get the permits approved; it shouldn’t be that time-consuming or that expensive,” he says, noting that oyster farms in states such as Virginia, Maryland, and New Jersey have more streamlined approval processes in place for budding shellfish farmers.

On any given day some one million oysters are growing at Hog Island. The farm shoots for harvesting about four million per year but mortality rates are high–around 50 percent. It’s an industry hazard that oyster farmers plan for; a survival of the fittest situation and ocean acidification doesn’t help an oyster’s odds of making it to the juicy, plump size consumers have come to expect.

In recent years oysters have seen a pendulum swing in popularity. Readily available until the early 1900s in San Francisco, they were an everyday food enjoyed by people at every economic level. Their reputation as a luxury, boutique item came later. These days, farmed oysters are being touted as an ecologically-responsible, lean protein alternative. American Catch author Paul Greenberg, for example, includes Atlantic oysters and other filter feeders in his short list of locally raised sustainable seafood that get the thumbs up for regular eating by U.S. consumers.

Meanwhile, the shellfish farmers at Hog Island are doing all they can to protect both a sustainable food source and their own livelihoods. That’s welcome news to die-hard bivalve fans, who maintain there’s something special, even exciting, about slurping a raw, live oyster off its shell.