Types of Oysters (Species)
In the US, more than 90% of commercial oysters fall into one of two species: Pacifics and Virginicas. Beyond that there are a few “speciality” species: Belons (a French species), Kumamotos, and Olympias. If the oyster was grown on the West Coast then odds are it is a Pacific. On the East Coast and in the Gulf they tend to grow Virginicas.
For those of you that happen to remember your high school biology it goes like this: Mullusca (phylum), Bivalvia (class), Pteriomorphia (subclass), Ostreoida (order) and finally Ostreidae (family), Crassostrea (genus) and finally Virginica (species). To put it all together a Virginica is a mullusc, that is a b-valve, that has two shells, lives in salt water, and are a true oyster .
Here is a quick overview of the main oyster types:
Virginicas: These are the oyster of the gulf and east coast. Go to New Orleans or Boston and this is what you will eat. They comprise more than 98% of the east coast and gulf oyster production. They are native to the Chesapeake and the rest of the east coast.
Pacifics: unlike the Virginicas, Pacifics are not indigenous to the West Coast of the US, where they are the predominant species. Originally, they are a Japanese species that was introduced to the West Coast as a commercial alternative to the native Olympia. The primary commercial advantage was the speed at which they grow to a viable size. In normal conditions a Pacific takes about a year to become “saleable” while an Olympia takes almost three. Thus, it was seen as a profitable alternative. They have thrived on the West Coast and largely supplanted the native oyster of Washington.
Olympias: these are the native oyster of the West Coast. They are smaller and slower growing. You can find them in the wild, on rare occassions, but they are not commercially produced.
Kumamotos: these are the second most common species commercially produced on the West Coast. They are smaller and slower growing, like the Olympias, than the Pacific. They have a loyal and dedicated following. In generally, their longer growing cycle makes them a premium oyster both in consumer preference and price. An additional challenge of the Kumamoto is that like the Pacific they are originally a Japanese Oyster. However, unlike the Pacific, they are a warm water oyster that does not natually spawn in the cool waters of the Pacific Northwest. Thus, they must be commercially spawned and then planted on the beds where they will grow.
Belons: these are the most desired oyster in France. In Paris they will sell for up to $15.00 each. They originated on the Belon River in France and are now produced in Maine. However, like sparkling wines, which can only be called Champagne when grown in that region, only oysters grown in Belon are allowed to be called Belons. Technically, they are a member of the European Flat Oyster Species.
Like Grapes, there is no single more significant influence on an oyster then the place in which it is grown. Because they are bivalves that filter water to eat, the more organisms in the water, the faster and fuller they grow. Oysters have been farmed for thousands of years. The Romans cultivated them in Italy. They thrive in brackish estuarine waters. This is why they grow so well in the Puget Sound, Louisiana (Mississippi River Estuary), the Chesapeake and our own Willapa. The higher the tidal flow the more they are submerged and then exposed to air the happier they are. They tend to prefer mud flats with lots of river silt. They need salt water to be really happy.
The major growing regions of the West Coast are the Southeaster portion of Maine (Lincoln County), Cape Cod area of Massachusetts, Long Island, Chesapeake, outside Charleston, the Florida Panhandle, Mobile Bay, Lousiana, Galveston Area, Tomales Bay (San Francisco Area), Puget Sound and the Willapa. For the most part all of them are estuaries with a large tidal flow (the Gulf States are the one exception).
Obviously, each species taste differently. A Virginica has a very briny (salty flavor) with a soft meat and a lettuce like flavor. A Pacific has a briny flavor with a cucumber and melon finish. Finally, Kumamotos are less briny with a honeydew melon finish.
While that may be the base flavor profile of each oyster; the actual flavor of a specific oyster on your plate will vary based on the temperature range, the salinity level and the brackishness of the water. For instance, there are three specific growing regions on the Chesapeake Bay: outside the bay on the peninsula (very salty and firmer), the inside of the peninsula (medium salinity and more liquid meat) and finally on the shore/river side of the bay (very little salinity and n even softer meat).
From our experience there is one factor that is not often recognized in an oyster flavor profile. That is growing methodology. There are a few most common methods: on bottom and off bottom (either on lines or in bags). On bottom oysters are grown in their natural method by simply lying on the bottom in piles or “hummocks”. The oysters grown in this method generally have an earthier flavor that produces a perfect bbq’ing oyster. We use them for baked, BBQ’d and Broiled oyster recipes. The earthiness of the “on-bottom” oyster tends to pair better with the butter, garlic, bacon and vegetables we pair with them.
Off-bottom have a less earthy flavor that is much better for eating raw on the half shell. The purity of the flavor tends to disappear when cooked. Producing off-bottom oysters is a much more expensive and time-consuming process. Off-bottom farming in large estuaries tends to look like the vines in a vineyard. To create an off-bottom production process the farmer will plant stakes about 3-4 feet tall in the bottom. They will then string lines between the stakes in straight lines about 150-300 feet long. Hanging from those lines will either be shorter strings on to which they attach the oysters of about 2 feet long or larger 2foot wide by 4 foot long plastic mesh bags into which they place the small oysters to grow.
So in sum, when you order an oyster, contemplate the species, the actual place with in the region and the type of production method used to grow them. It’s that simple. Because just like every rose has a fantastic flavor, each oyster done well tastes wonderful. And I have found learning about them is as much fun as learning about the nuances of wine…without the potential for a hang-over.