“I just visited a raw bar for the first time. I had some good oysters but was stunned and a little intimidated by all the varieties there are! How do you choose? And is it true you can only eat oysters in the r months?”
My colleague Sarah McColl recently wrote about the charms of eating oysters at home, which is how I grew up eating them—but indulging at an oyster bar like that at Grand Central Terminal, where there are usually 30 or more different options available on the half shell at any given time, can be a bit overwhelming.
What makes oysters so alluring, of course, is that their flavor characteristics—briny, sweet, creamy, metallic, even a faint touch of melon or cucumber—come in large part from the waters in which they grow and the microalgae on which they feed. That’s one reason each “variety” is named for the place it’s harvested.
Another reason is that producers are trying to create their own signature oysters by growing them differently—and in some cases, their evocative names have nothing to do with where they’re actually cultivated. Meaty, briny Blue Points, for instance, used to be from Long Island’s Great South Bay. They were brought there from the Chesapeake by one Joseph Avery around 1812. But as Robb Walsh explains in Sex, Death & Oysters: A Half-Shell Lover’s World Tour, Blue Points became so popular that from 1817 on, the term was used to describe all the large oysters produced in the Great South Bay. “Legend has it that when sewage pollution ended oystering in the Great South Bay,” Walsh writes, “the Blue Points were dredged up and replanted all over Long Island Sound so their strain could continue.” These days, Blue Points may come from Connecticut, New Jersey, or Virginia.
In any event, the hundreds of specifically named oysters in the United States and Canada all come from just five species that are cultivated commercially. To help figure out your oyster eater profile, you can turn to a guide like that of Rowan Jacobsen, author of Geography of Oysters: The Connoisseurs’ Guide to Oyster Eating in North America.
Or, if you have the wherewithal, settle in at a top-drawer oyster bar and educate yourself by ordering oysters in flights, like wines. Robb Walsh has the right idea. First, order two each of all the Canadian oysters available, then two each of all the varieties from New England, followed by Long Island and Chesapeake oysters. Then turn your attention to the Pacific oysters of Washington, Oregon, and California. Prejudice because of the risks associated with Vibrio (more about that in a sec) means that Gulf oysters are a rarity at oyster bars outside Louisiana, Texas, and elsewhere on the Gulf Coast. These days, you could say they’re a rarity, period; four years after the Deepwater Horizon oil spill, stocks have (surprise!) declined precipitously.
By the way, if you talk to enough oyster lovers, you’ll discover that the Latin species names have become part of the vernacular, so it helps to have a passing familiarity with them.
Eastern (Crassostrea virginica): Indigenous to the East and Gulf coasts of North America, virginica is the quintessential American oyster—uncomplicated, with a great oceanic tang. That said, there’s a big difference between a clean-tasting Wellfleet from Massachusetts and a sweet, creamy Apalachicola from the Florida Panhandle. Virginicas are cultivated on the West Coast as well. One of the most popular is the Totten Inlet virginica, raised by Taylor Shellfish Farms in a bay off Puget Sound. A passion of seafood authority and genius promoter Jon Rowley, it is exceptionally sweet and plump, with a lovely mineral finish. If you’re leery of large oysters, I beg you to try a Totten Inlet virginica—and don’t be afraid to chew to extract every molecule of flavor.
Pacific (Crassostrea gigas): This species was brought to the U.S. from Japan in the 1920s, because the Olympia (see below) had become almost extinct. It’s a hardy oyster, very disease resistant, and today the most common oyster cultivated on the West Coast and in Europe. In general, these oysters are sweet, mild, and rich. One relatively new trade name you’ll see at oyster bars is Kusshi, which are gigas oysters that look like the wildly popular Kumamoto (see below). They’ve been “tumbled”—continuously rotated in a contraption that looks a bit like a compost tumbler (or a bingo machine) so that they develop a deep cup of a shell instead of a ruffly pointed end.
Olympia (Ostrea lurida): This oyster, the only species indigenous to the West Coast, may be tiny, but the meat is well developed and boasts a deep, coppery flavor. It was so sought after in California restaurants during the gold rush that it was virtually harvested to extinction. Local oystermen fought to preserve it, but in the 1920s and ’30s, pollution took its toll. These days, supplies aren’t exactly abundant, but Oly populations are being reestablished by the Puget Sound Restoration Fund. Its partners include local and state governments, commercial shellfish producers, and Native American tribes.
Kumamoto (Crassostrea sikamea): This small, deep-cupped oyster is originally from Kumamoto Prefecture in Japan. It’s now cultivated successfully in Washington, Oregon, California, and even the chilly offshore waters of Mexico. Its petite size and balance of sweetness and brininess make it a raw-bar favorite, especially of novice oyster consumers.
European Flat (Ostrea edulis): This round, flat-shelled oyster, native to Europe, is the most robustly flavored oyster on the planet, with a strong mineral aftertaste that you either love or hate. Known by such legendary place names as Belon, Marennes, and Colchester, it was esteemed by Roman emperors and Louis XIV, the Sun King. After hundreds of years of overfishing, the parasite Bonamia, and an increasing preference for smaller, milder oysters, edulis has almost disappeared in Europe. In North America, it’s cultivated on both the East and West coasts, with place names that include the word flat. Westcott flat (from northern Puget Sound) and Maine flat (Boothbay Harbor) are two examples.
Oysters and the R Months
As to the business about eating oysters only in the r months (September through April), one of the clearest explanations is in Walsh’s Sex, Death & Oysters. “When water temperatures get colder at the end of the summer, oysters begin storing a carbohydrate compound called glycogen,” he writes. “To humans, glycogen tastes like sugar. As the water gets colder, more glycogen accumulates, and the oysters get plumper and taste sweeter.”
But why not slurp in the warmer months? Quite simply, the oysters might not taste as good. “With the onset of warmer water temperatures in April, oysters begin to convert glycogen to gonad (reproductive material),” he continues. “As the summer approaches and temperature rises, the oyster progressively loses its sweetness, becoming more and more ‘fishy’ tasting. It’s not an unpleasant flavor—in fact, many oyster lovers like it—but it isn’t sweet. In early summer, when the oyster is spawning, it becomes slimy and produces a white milky substance that almost no one wants to eat.” In late summer, after they spawn, oysters lose their plumpness and most of their flavor. In the words of Jon Rowley, they deserve their privacy.
Winter is also when oysters are safest to eat. The warmer waters of summer encourage the growth of bacteria, such as Vibrio vulnificus, found in Gulf oysters. Its presence has nothing to do with pollution. “It’s a naturally occurring bacteria that multiplies in warm seawater,” Walsh explains. “So in the hottest part of the summer, the amount of Vibrio in the water is extremely high. And if oysters harvested in the summer aren’t properly refrigerated, the bacteria level in them can climb even higher.” When in doubt, do as Walsh does and check the exact water temperature in the marine section of the weather report. When it’s below 65 degrees at the point of harvest, then little to no Vibrio vulnificus is detectable.
Walsh used to make an exception for triploids, sterile oysters from northern waters, which are fat and sweet in July and August. “But thanks to global warming,” he writes, “another harmful bacteria, Vibrio parahaemolyticus, appears to be moving farther northward. Raw shellfish consumed in the warm summer months have sickened people in Washington state and even as far north as Alaska.” To me, oysters, like tomatoes and yellow squash, are a seasonal delicacy. I don’t eat tomatoes and crooknecks in the winter, and I lose my taste for oysters in the summer. Hooray for September! My local Peconic Bay virginicas are fattening up for the winter and taste absolutely wonderful.