Every year at the Boston Seafood Expo, we put out our huge display of live oysters and shellfish. And every year, we get surprised looks from people who are shocked that so many oyster varieties exist, let alone in one place. Most of them approach us and ask, "How are there so many varieties of oysters?" It's a question we get pretty often, so we thought it was worth sharing with everyone. To answer this complex question, we have to revisit the oyster basics.
There are three fundamental factors that make an oyster "unique": its species, its environment, and its growout method. The word unique is in quotes because many in the food industry consider two oysters, which may be exactly the same, but with different brands, to be their own varieties. Brand differentiation due to increased marketing has definitely changed the product landscape. Therefore, to account for this trend, there are really FOUR factors that make an oyster unique: its species, environment, growout method, and branding.
If you can remember your high school math class, you probably learned something about combinations and permutations (who would have thought math would be relevant to oysters). In essence, the number of varieties in the world are equal to the unique combinations of those four factors. For example, a Crassostrea virginica beach-grown in Puget Sound, WA, aka the Totten Virginica Oyster, is different from a Crassostrea gigas beach-grown in Puget Sound, WA, aka the Totten Inlet Oyster. The primary difference between those two oysters is their species, but it makes them taste and look insanely different. Understanding these factors will help explain why so many oyster varieties exist.
There are many species within the oyster family, Ostreidae, however, not all of them are edible. The family is made up of over 10 genera, but most common edible oyster species stem from the Crassostrea, Ostrea, and Saccostrea genera. The following are the most familiar species that are commercially consumed or cultivated today:
There are other edible oysters like Mangrove Oysters (Crassostrea gasar), but they are typically not available commercially. It goes without saying that an oyster's species is important because it plays a huge role in determining its general flavor and shell shape.
If you're in to oysters, you've probably heard the word "merroir." Adapted from the word "terroir" for wine, merroir describes the flavor an oyster takes on from its environment. Oysters are filter feeders, so the make up of its immediate waters influences the flavor of the oyster. An oyster grown in an estuary where freshwater and seawater meet will be less briny than an oyster filtering ocean water all its life. An oyster grown in a bed of seaweed will have more seaweed notes and green accents than an oyster grown out in open water. Every location has its unique characteristics, so oysters grown in different places will have separate looks and flavors.
The Shigoku Oyster is one of my favorite examples to demonstrate how growout method affects an oyster.
Shigokus are a Crassostrea gigas species, and typically gigas oysters have fluted and ridged shells as shown on the right. However, Shigokus are grown in hanging bags that never touch the ocean bottom, and they are constantly being tumbled by the height of the tide. This growout method produces a smooth mussel-like shell, firm meats, and deep cups, making the Shigokus distinct from its brethren. A farm may grow only one species in one location, but by using different growing techniques, the grower can create multiple oyster varieties.
One of our brands at Pangea Shellfish are the Mayflower Point Oysters grown by the Big Rock Oyster Company in Dennis, MA, who also sell their oysters as Big Rock Oysters now. In a side-by-side taste test, we had someone tell us that the Mayflower Points tasted better than the Big Rocks, but little did the person know that they were the same oyster.
Brand differentiation allows more oysters to have a niche in the market and generate consumer loyalty, but it also changes the definition of what an oyster variety is today. In our bay of Duxbury, there are multiple oyster brands. Just to name a few, there's our Standish Shore, Island Creek/Row 34, Merry Oysters, Hungry Pilgrim, Blue Yonder, and Powder Point. All of them are the same species, grown in the same bay, and have similar growout methods, but there are those who assume that they are different varieties. Branding oysters is an interesting debate (read the different opinions here), but since it's not going away, it's a factor we should consider.
Because there are so many locations to grow oysters and infinite potential brands, the answer to the question is that there will always be infinite varieties of oysters... or infinity factorial. In other words, there will always be new oyster varieties because a grower may discover a new technique or someone may decide to cultivate oysters in a new area. The list of varieties expands every day, and that's what makes oysters interesting! There will always be new oysters to discover and eat!