There is a frustrating gap between what oyster menus tell you and what you need to know to order well. Menus give the name, the origin, sometimes the species, and the price. They rarely give the salinity of the growing water, the current condition of the batch, whether the oysters have just spawned, or what they will taste like. A guest who wants a very briny oyster and one who wants a gentle, sweet one are asking for different things, and the menu gives them both the same information.
The Brine Spectrum
Brine is the most useful single guide to what you are about to eat, and geography predicts it well. Oysters are osmoconformers, meaning their body fluids follow the salinity of the water they live in,1 so the growing water largely sets how salty the flesh and liquor taste. An oyster from 32 ppt seawater is noticeably brinier than one from 22 ppt estuary water, and you taste the difference at once. Three rough bands cover most menus.
High brine (open coast, full-strength seawater, little fresh water). Wellfleet, Chincoteague ("salt, salt, and more salt," in the distributor Pangea's words), Aunt Dotty and Cancale sit here. The salt arrives before anything else, and newcomers can find it a lot. Ask for oysters from open or ocean-fed water, and drink something with sharp acid, like Muscadet, Chablis or Blanc de Blancs Champagne.
Medium brine (sheltered bays and inlets with some fresh water). Malpeque ("moderate brine", says the distributor Pangea), Beausoleil, Mystic and Fanny Bay sit here: enough salt to taste of the sea, with sweetness close behind. They are the easiest to pair and the safest order if you are unsure.
Low brine (estuaries with a lot of river water). Little Skookum, James River, Rappahannock and Choptank Sweet lead with sweetness and body instead of salt. Order them if briny oysters put you off, or if you plan to pile on a strong mignonette.
The Questions to Ask
At a raw bar or oyster restaurant, these questions, asked straight to the server or shucker, get you what you need.
Which is the brinier option, and which is the sweeter? Anyone who has opened a few of each can answer it, no special vocabulary needed.
Are these in good condition right now — have they spawned recently? In summer and early autumn, some of the oysters on any given raw bar will have recently spawned and be thin and watery compared with their winter and spring best. A server who knows the oysters can tell you.
Where in the [growing area] is this from? Names like Malpeque, Hood Canal or Long Island Sound cover a lot of water, and flavor changes within them. Salinity, food and current can change within a few miles in a long inlet or a big bay; the Malpeque Bay oyster proper differs from the broader range of Prince Edward Island oysters sold under the name. When the name on the menu is broad, ask for the bay or the farm.
Is there a European flat on the menu? If the answer is yes and you have never eaten one, order it. Tasting a Pacific or Eastern oyster beside a Belon, a Loch Ryan native or a Galway native shows how much species matters to flavor. It tastes like a different food.
Species as the Deepest Predictor
Beneath the geography of brine, species is the deepest predictor of how an oyster tastes, and menus ignore it most often. Pacific oysters (Crassostrea gigas) tend to be sweeter, with the cucumber-to-melon aromas that come from a compound Eastern oysters largely lack,2 and their brine runs from medium to high depending on the site. Eastern oysters (Crassostrea virginica) range widely with geography, from very briny and mineral in Maine and New Brunswick to sweet and gentle in the Gulf of Mexico and the lower Chesapeake tributaries. European flat oysters (Ostrea edulis) are in a different category from both: iodine, mineral and savory, with a metallic finish that some eaters find the most interesting flavor in oysters and others find too much.
Species and water together let you guess well before the first oyster. The guesses still miss sometimes, because batches and seasons vary.
The Most Useful Single Piece of Advice
Above all, ask the shucker what they would eat right now from what is on the ice. Skip what is generally best or most popular and ask what they would eat, given what they know about each oyster's condition this week. They have been opening and tasting these oysters all day, and nobody else in the room knows more.
- Zhao, X. et al. (2017). Identification and expression of cysteine sulfinate decarboxylase, possible regulation of taurine biosynthesis in Crassostrea gigas in response to low salinity. Scientific Reports, 7, 5505. doi.org/10.1038/s41598-017-05852-6
- Josephson, D.B., Lindsay, R.C. & Stuiber, D.A. (1985). Volatile compounds characterizing the aroma of fresh Atlantic and Pacific oysters. Journal of Food Science, 50(1), 5–9. doi.org/10.1111/j.1365-2621.1985.tb13265.x