The Color of Oyster Envy

Green oysters are real, delicious and may be coming to a restaurant near you
Photo: Dave Katz/Tasting Table

Not long ago, I was giving a talk in Raleigh on North Carolina's potential to become the Napa Valley of oysters. (I wrote a guidebook about oysters a few years ago and have kept tabs on the industry ever since.) If you glance at a map of the state's fractal coastline, you'll see my point: North Carolina has an abundance of the temperate, well-sheltered, mid-salinity estuaries where oysters thrive. It's always had decent wild populations, but to truly reach Napa Valley status, it needs to adopt the hands-on cultivation methods that produce premium oysters. Look at France, I argued, PowerPoint clicking away, where dozens of different techniques are used to produce oysters with unique shell shapes, flavors and looks.

For my pièce de résistance, I showed some slides of fines de claires oysters from France's Marennes-Oléron region, which are finished in rectangular clay ponds (claires) in water that turns jade due to the abundance of a blue diatom (a type of microalga) called Haslea ostrearia that is the world's best producer of blue pigment. The oysters feed on the diatom, which stains their gills the most extraordinary shade of olive. For centuries, the French have celebrated these fines de claires. An 1892 book explains that "the green color is said by the connoisseur to give the oyster an inimitable and exquisite flavor, as if savored with mushroom or truffle, an idea which the culturist, however skeptical, is not apt to refute." Certainly not—the growers get twice as much for their green oysters as for their regular stock. Not surprisingly, they go to great lengths to nurture the populations of blue diatoms in their ponds.

In Raleigh, I had mentioned the green oysters just to show an extreme case of the possibilities of oyster aquaculture. And after my talk, a large man with a mustache, long reddish hair and myriad piercings approached me. He could have been a Viking or a biker. "My name is David Cessna," he said. "People call me Clammerhead. I've been harvesting oysters for five full decades. I see those green gills on my beds every winter. They taste great. But I can't sell the damn things."

Green gills? Here in America? Growing naturally? I'd never heard of such a thing.

After chatting with Clammerhead and digging into some old oyster books, I learned that green gills have been around forever. They turn up as far north as Long Island, but the southeast is their main stomping ground. Ernest Ingersoll noted the phenomenon in his 1881 bible, The Oyster Industry, pointing out that "the existence of it does not impair the quality of the oysters, but it does materially affect the sale, because people generally are ignorantly afraid of it."

Yes, they are. Green is not a color we like to see in our meat. An 1879 issue of Forest and Stream Magazine relates the story of a company of sportsmen who dined in an oyster saloon in Richmond, Virginia, and to their horror were served a plate of green oysters. Downplaying rumors that the oysters derived their color by dining on "copperous banks" created by the festering remains of Civil War soldiers, the waiter assured the sportsmen that "Dey's de best oyster comes here. Dey gets green from eatin' seaweed." To no avail; the sportsmen rejected the oysters, and Virginia failed to become America's Marennes-Oléron.

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But now North Carolina just might. Its estuaries seem to have ideal conditions for green gills. Clammerhead harvests his in the North River marshes, near Beaufort, which seems to have the most robust natural populations of blue diatoms to be found. The oysters look normal for most of the year, then, in late fall, as the water cools, they turn jade green and the oysters' gills go turquoise. By Christmas, they are in their full olive glory. By March, it's all over till next year.

The flavor is even more remarkable. After cajoling Clammerhead into shipping me a box of green gills, I admired their stunning white-and-green shells and then got down to business. Inside, they had beautiful ivory flesh contrasting with those crazy gills. I slid one into my mouth. Wow. Sweet, salty and the French aren't kidding about the truffle thing. There's also a hint of spinach soufflé. Whatever you call it, they're amazing and unique and quite possibly incredibly good for you—the blue pigment, which is known as marennine, has been found to have powerful antioxidant, antibacterial and antiviral properties. Research into its medical use is underway. In the meantime, one thing you can be sure of is that you are very unlikely to get sick from eating green gills.

If you can find them, that is. Short of hopping a charter flight to Marennes-Oléron, it ain't easy to taste a green gill. Dealers don't want to have anything to do with them, so harvesters have traditionally sold them to a few locals who were in on the secret. But that's about to change. Clammerhead has teamed up with Dr. Niels Lindquist of the University of North Carolina's Institute of Marine Sciences to form the Sandbar Oyster Company, which has developed a new technique (patent pending) for raising native green gills that have the strong shells and deep cups of the best cultivated oysters. They've trademarked the name Atlantic Emeralds and are working with restaurants and distributors to introduce Emeralds to the world in the fall of 2016. I'm hoping to get down to Beaufort myself for the launch party.

I know, I know, you don't want to wait. Green gills, after all, are at their peak right now. What to do? Well, Clammerhead says he can try to fill a few orders. But if you're anywhere near the mid-Atlantic coast, you might want to scout around. No one has figured out why Haslea ostrearia turns up in the places it does, but wherever it does, it tends to come back every year. So if you find a nice pocket of green gills, you might want to keep the secret to yourself.

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