People have enjoyed eating shellfish for centuries, and possibly even millennia. Historical records point to the establishment of oyster beds as far back as 100 B.C. Ancient Chinese and Roman cultures developed methods for growing and harvesting oysters.
In the United States the Eastern oyster, Crassostrea virginica, played an important role in the Native American diet, and served as a food staple for European settlers. By the mid-19th century, Americans had become enamored with oysters, shipping them inland on so-called “oyster expresses” and “oyster caravans.” Almost every large city in the eastern United States had an “oyster parlor,” a precursor to modern-day oyster bars.
Today, the Southern tradition of oyster roasts — large gatherings where people enjoy oysters cooked over an open fire — is still popular. There also is a growing demand in restaurants for oysters served raw on the half shell.
Wild shellfish such as oysters have been harvested from North Carolina coastal waters for hundreds of years. But shellfish also can be cultivated. Since 1858, North Carolina has allowed the use of public waters to commercially grow shellfish, provided that producers apply for and obtain a lease.
The N.C. Division of Marine Fisheries oversees the state’s Shellfish Lease Program. The leasing process ensures that shellfish are sustainably grown in high-quality coastal waters, without affecting public access or recreational activities.
To cultivate oysters, in North Carolina growers traditionally planted oyster shells on lease bottoms, creating a place for free-swimming oyster larvae to attach and become oyster “spat.” Growers also planted oyster shells to which oyster larvae have already attached, known as “spat on shell.” After planting, the spat feed on phytoplankton as they grow.
With this production method, oysters are normally harvested once they reach a market size of approximately three inches, which takes two to three years. Because each planted oyster shell typically contains several seed oysters, the oysters grow in clumps that are mainly suitable for oyster roasts or shucking.
In recent years, an increasing number of North Carolina oyster producers have been growing their oysters in the water column. This method entails placing oyster seed into cages that are floated or are suspended off the water bottom. As the oysters grow, they are periodically sorted according to size and are transferred to other cages to reduce crowding.
Growers using this process must also regularly repair, inspect, and clean cages and bags to remove predators such as crabs and to ensure that water flows freely through the oysters so they can feed and grow.
While water-column cultivation is more labor intensive, the technique produces consistently sized, single oysters with deep cups that typically have more meat in them than wild oysters or those planted on the bottom. Because the oysters are not in contact with the water bottom, they are generally free of grit. These attributes are prized by high-end restaurants that serve oysters on the half shell.
Cultivated Shellfish are a Sustainable, Environmentally Friendly Seafood Choice
Shellfish cultivation is a highly sustainable way of producing seafood. Cultivated shellfish get nutrition from their surroundings, so they don’t require added food, chemicals, or antibiotics to grow. They also can’t be over-harvested, and they relieve pressures on wild shellfish populations. When growers harvest cultivated oysters or clams, they remove no more shellfish from the water than they originally put into it.
The coastal environment also benefits from shellfish production. When oysters and clams feed, they filter water, thereby improving its clarity and quality. In fact, a single oyster can filter up to 50 gallons of water a day. Clearer water fosters the growth of marine vegetation, which in turn provides habitat for sea life, such as juvenile crabs and finfish.
SOURCE: Content on this page was sourced from the NC Sea Grant. https://ncseagrant.ncsu.edu/aquaculture/north-carolina-cultured-shellfish/