Wild Oysters
The top shell of a wild oyster is no different than that of a cultured oyster, flat and smooth. The bottom shell of a wild oyster has a noticible scar at the narrow hinged end, where the oyster had been attached to a rock, stick, ledge, shell or other substrate.
A wild Oyster will often have a more fluted, wavy shell with more ridges than it's cultured cousin. This is due to more variability in daily and seasonal growth patterns. Wild oysters are subject to wider ranges and higher frequencies of temperature fluctuation, resulting in irregular growth and a shell with 'character'.
Cultured Oysters
Cultured oysters are held in conditions which limit extreme temperature fluctuations in order to maximize growth. The goal of an oyster aquaculturist is to produce oysters with similar growth rates, shell characteristics, and sizes, creating consistency in the marketplace and visual appeal, as well as operational efficiency. As a result of rapid, consistent growth rates, many of the ridges and wrinkles present in a wild oyster never have a chance to form in a cultured one.
Cultured oysters also lack the scar that marks the point of attachment of a wild oyster to it's cultch. When larval oysters are ready to metamorphose and become bottom-dwelling shelled creatures, they locate a substrate or 'cultch' to attach to, then proceed to grow a shell and transform into benthic organisms. Wild Oysters will 'set' on whatever substrate is available in the natural environment, usually rocks, shells or other oysters. When larval cultured oysters grown in the controlled environment of a shellfish hatchery are ready to set, the substrate available to them is usually very small pieces of ground up shell hash. The 'cultch' becomes indistinguishable from the oyster's own shell, producing a 'cultchless' oyster with no scar from the point of attachment. A cultchless shell is the primary distinguishing characteristic differentiating a cultured from a wild oyster.
In the state of Maine it is illegal for anyone to possess a cultchless oyster without a permit or receipt proving that the cultchless oysters were purchased from a permitted grower or legitimate source.
Damariscotta's Gone Wild!
A wild oyster population has been re-established in the Damariscotta River estuary! Every year local aquaculturists grow tens of millions of oysters in the Damariscotta. Over the past decade the cultured oysters on leased beds have spawned. The oyster larvae are carried by currents along the shore, often miles from the original aquaculture leases. The larvae then metamorphose and develop a shell, attaching themselves to rocks, ledge, or shell hash. The once extinguished wild oyster fishery of the Damariscotta River has returned. Pockets of wild oysters can be found by beachcombers and explorers at low tide in the upper estuary. If you are planning on collecting oysters be sure they are not from an aquaculture lease site, and check the status of Red Tide and Water Quality closures using the links provided before harvesting.
Click on the links below to access important information from the State of Maine Dept. of Marine Resources: