Oyster bed restoration project started in Tisbury Great Pond

Bags of scallop shells that will be used in the next phase of a one-acre oyster restoration project in Tisbury Great Pond.
Photo by Christy Aumer

Bags of scallop shells that will be used in the next phase of a one-acre oyster restoration project in Tisbury Great Pond.

The Nature Conservancy (TNC), along with several Island organizations, began work this month on a one-acre oyster bed restoration project in Tisbury Great Pond. The goal is to augment the existing oyster population and create a self-sustaining wild oyster reef that will provide a model for future shellfish restoration.

Shellfish experts said that although oysters are present and harvested seasonally in portions of the pond, which is shared by West Tisbury and Chilmark, the restoration will take place in an area where divers discovered oyster shell remnants of an oyster reef.

Jon Kachmar, TNC Southeast Massachusetts Program Director, said since there is a native oyster population in Tisbury Great Pond, it gives the project an advantage. “It gives you an upper hand,” he said. “We know oysters can survive there, you’re not starting from scratch.”

Mr. Kachmar, who focuses his work on restoring coastal resources, said juvenile oysters require a hard bottom to spawn, or release eggs and sperm into the water, so it’s important they are not placed on a muddy bottom.

On Saturday, a team from TNC, along with town shellfish wardens from Chilmark and West Tisbury, made several trips via barge from Sepiessa Point Reservation to a designated one-acre site in Town Cove to dump enough surf-clam shells to cover 60 cubic yards. The project will cover a total of around 100 cubic yards in the 736-acre Tisbury Great Pond.

Project members worked for several hours using an excavator to move surf-clam shells from a dump truck to a barge, and then traveling across Short Cove to Town Cove to unload the surf-clam shells in specific areas to create a hard surface foundation for juvenile oysters to attach, and hopefully spawn.

Nearby, TNC interns Benjamin Miller and Forrest Carroll stuffed scallop shells into nets in preparation for the next phase of the project. The bags of scallop shells would be transported to the MV Shellfish Group, where juvenile oysters, or spat, will hopefully attach to the scallop shells. Mr. Kachmar referred to this process as “spat on shell.”

Rick Karney, shellfish biologist and director of the Martha’s Vineyard Shellfish Group, said once the juvenile oysters have attached themselves to the scallop shells, they would most likely be hanged from floats for several weeks in July or August. Later, the bags will be opened and the contents dispersed over the surf-clam shells. The strategically placed piles of surf-clam shells on the bottom of Tisbury Great Pond, Mr. Karney said, will hopefully expand to join one another and create an environment similar to a coral reef.

“They’ll [oysters] build these nice reefs with nooks and crannies,” Mr. Karney said. “It provides all kinds of places for all kinds of animals to grow.”

Besides providing a habitat for other fish and critters, oyster beds can remove polluting nutrients, like nitrogen. Oysters are good, natural filters for water, Mr. Karney said. They can filter approximately 50 gallons of water a day, he added.

Mr. Karney said oysters are considered a “keystone” species. He said it’s important to preserve them since they are important to maintaining or even improving water quality as well as cycling nutrients and providing a coastal ecosystem.

Globally, Mr. Kachmar said, 85 percent of oyster beds are gone. “Unfortunately, we take the oyster shell out of the pond and in most cases it doesn’t go back,” Mr. Karney said. “And as we harvest the oysters, we’re destroying the habitat.”

Besides over harvesting, and the use of oyster shells for things like roads and driveways, Mr. Kachmar said, humans aren’t all to blame. “Disease plays a big role,” he said, adding that the surf-clam shells were cleaned prior to being unloaded into Tisbury Great Pond. “Ponds can be isolated from the rest of the ocean. It can be good because they can keep disease out. But, it can be bad because disease can wipe out a population.”

Restoring oyster beds for ecological purposes is fairly new in Massachusetts, according to Mr. Kachmar, but he said New England is catching on. “Our need is no less than anywhere else,” he said. “We’ve devastated these beds. Slowly, but surely.”

Specifically on Martha’s Vineyard, Mr. Karney said there are efforts to create a more sustainable environment for oysters. He talked about restoration work on Edgartown Great Pond, and progressive shellfish recycling programs.

“It’s good to save the shells that are being shucked in restaurants, and get in place a mechanism to save that resource,” Mr. Karney said. “They shouldn’t be thrown in the trash.”

“We hope to create sustainable levels of growing and harvesting so people can continue to enjoy good, local seafood and continue to commercially and recreationally fish,” Mr. Kachmar said. “But at our trajectory, we’re losing that.”

TNC will monitor the project for the next two years.