Town of Nantucket: Shell Recycling 30 Miles Out at Sea

To: Bluedot Living 

From: Town of Nantucket, Natural Resources Department; Assistant Biologist, Griffin Harkins 

Subject: “Shuck it for Nantucket” Shell Recycling 30 Miles Out at Sea

Over the past several decades there has been a stark decline in prevalence of wild oyster reefs along the East Coast of the United States. This decline has been largely due to historically unsustainable wild harvest methods and habitat destruction that ultimately led to oyster shells being permanently removed from the water. Oyster shells are the foundation for oyster reefs, and when wild harvest on reefs occurs and shells aren’t returned, oyster larvae lose a preferred substrate to set and develop on. The disappearance of many coastal oyster reef systems has made it even more apparent that oyster reefs were instrumental in providing valuable ecosystem services. Many know of the incredible filtration ability of oysters, where one oyster can filter roughly 50 gallons of seawater a day; however, many overlook the plethora of other ecosystem services they provide, such as coastline protection from storm surges, increased habitat and biodiversity, food creation, sediment retention/seashore stabilization, carbon burial, and more. 

The island’s shell recycling journey started in 2014 to address this issue. While many existing oyster reef restoration projects aim to restore once existent oyster reef systems at a large scale, on Nantucket the goals are slightly different. 

Nantucket is unique in the sense that there were not plentiful, extensive oyster beds throughout our waterways like much of the East Coast, largely due to the sandy structure of the island. Wild oysters can still be found on Nantucket attached to certain hard structures, but there are no wild oyster reefs in existence today, nor were there any large-scale reefs throughout the island. So the goal of Nantucket Island’s Shell Recycling Program is to preserve a limited resource (the oyster shell) to leverage the ecosystem functions of an applied oyster reef to address a specific ecosystem concern within Nantucket’s waterways. Since 2014, the community has worked with the Town of Nantucket’s Natural Resources Department to recycle oyster shells. To date, over 500,000 pounds of oyster shells have been recycled from more than 20 Island restaurants and raw bars, keeping them from entering the landfill. Over a hundred thousand pounds of recycled shell was used from 2017 to 2020 to create Nantucket’s first oyster reef restoration project in Shimmo Creek (a saltwater creek connected to Nantucket Harbor), and it gave the Town of Nantucket’s Natural Resources Department valuable insight into what works and what does not work as far as implementing an oyster reef restoration project on-island. The Natural Resources Department operates a state-of-the-art shellfish hatchery located on Brant Point. Here they can produce millions of oyster larvae and rear them to the appropriate life stage to then set them directly on recycled oyster shells. Loose oyster shells from the Town’s shell recycling pile are bagged up in large diameter mesh “shell bags,” where they form a more rigid structure that aids in retaining the oyster reefs shape in the water. In the Town’s hatchery, oyster larvae have been set on loose shell and shell bags. This process is done to “kick start” an oyster restoration project by providing a stock of oysters already growing on the recycled shell, so when they start reproducing in the wild their larvae will then recruit and set on the abundance of recycled shell around them. The Town’s Natural Resources Department has also collaborated with other island organizations to implement an oyster reef, and to provide education to the community on the importance of shell recycling and oyster reef restoration. Currently, there is a large surplus of oyster shells curing at the Town’s shell pile. Shells must cure for at least a year prior to being reintroduced to Nantucket’s waterways. 

Being an island 30 miles out at sea, Nantucket must rely on its community to recycle and preserve oyster shells, as shipping barge loads of shell is not practical or sustainable for the long term. The Town of Nantucket’s Natural Resources Department continues to investigate ways to strategically implement restorative oyster reefs around the Island that will provide the highest potential for ecosystem services. In the meantime, Town shell recycling technicians will aim to recycle at least 50,000 pounds of shell a summer season to maintain a plentiful stock of oyster shells. 

For more information, visit Shell Recycling Program.