Cultch needed

Recycle those Oyster Shells

by Amandine Surier

Recycle those Oyster Shells

Genevieve Jacobs

The lifecycle of an oyster is dependent upon a substrate on which larva can settle. Spent oyster shell is the perfect material for robust next generations.  

“I want to start a shell collection” said Jessica Kanozak, one February morning in my office. She had called the day before to ask if she could stop by to talk. I had been Jess’ supervisor for three years while she worked at the shellfish hatchery. She had been a good worker: efficient, quiet, and one of the few that took initiative. After leaving the Shellfish Group she had joined the staff of the Offshore Ale Company in Oak Bluffs, and was about to be promoted to floor manager. I looked at the familiar angelic blond curls and dark blue eyes, contrasting with the hard look of resolve she always had on her face, and I wondered for a full minute why on earth she needed me to collect sea shells. Then I caught up. “You mean a shell collection program, for restaurants?” “Yes,” she said calmly, “and I need you to help me.”

Oysters and other bivalves build their shell with a fleshy flap called the mantle, which envelops and protects all the other organs. Shell appears in the very early stages of development, when the oyster is only a few days old and still swimming among the plankton. Oysters produce shell slowly one layer at a time by extracting calcium from the water and transforming it into calcium carbonate.

When an oyster larva is ready to set (metamorphose from a swimming to a sedentary organism), it investigates the pond, looking for the best place to settle. The substrate the larva selects needs to serve as a shelter from predators like crabs and fish, but it also needs to protect its thin fragile shell from the ocean’s rising acidity levels that result from the dramatic increase in atmospheric carbon dioxide (CO2). Adult oyster shell is that perfect substrate. Its three-dimensional structure physically protects the seed when it is most vulnerable, and its chemical composition (CaCO3) neutralizes water, creating PH-friendly microclimates where the larva can cement and live safe and sound.

When adult oysters die of natural causes, their shell becomes cultch (points of attachment) for young oysters, but when the oysters are harvested, their shell is taken from the ponds and often doesn’t make it back. After more than a hundred years of humans’ using shell as construction material for roads and driveways and as chicken feed supplements, or simply disposing of it in landfills, pond bottoms have become barren, inhospitable mud pits without suitable substrate.

A few years ago, biologists demonstrated that oysters, beyond supporting traditional fisheries, clean estuaries and ponds by acting as bio filters. Since then, oyster restoration programs have become a popular means to help coastal waters with rising nitrogen levels and are being funded in almost every coastal state in the United States.

On a practical level, restoring oysters reefs requires oyster larvae and shell—a lot of it. This year, Martha’s Vineyard’s very own oyster restoration program in Edgartown Great Pond and Tisbury Great Pond found the truck loads of shell it needed from a sea clam processing plant in Rhode Island. But what about next year? With years of overfishing, pollution, and climate change, and oysters’ favorite habitat being taken away, shellfish populations on the East Coast are now reduced to 1% of their historical peak. So is their processing byproduct: shell. Shell is becoming rare, and demand is rising. This is definitely a good reason to think twice before tossing your oyster shells in the trash at a raw bar.

That is why Jessica had come to see me that morning. Although now a familiar face at Offshore Ale, she holds a degree in Aquaculture and Fishery Technologies from the University of Rhode Island. With one foot in the restaurant business and the other in the shellfish community, for years she has watched shells go in the trash while oysters populations struggle in the great ponds. Encouraged by the success of shell recycling programs in New Hampshire, North and South Carolina, Maryland, and Virginia, she decided it is time for Martha’s Vineyard to join the movement.

The project found the financial support it needed with the Edey Foundation, which granted the Martha’s Vineyard Shellfish Group enough money for a trailer, a trailer hitch, some barrels and some salary money for Jess to do her restaurant rounds three times a week. “Until we received this proposal, we were unaware of the importance of shell in the life cycle of oysters,” said Beatrice Phear, chair of the Edey Foundation. “We are delighted to support this project and very excited that restaurants will join in this venture.”

The Lookout Tavern, l’etoile, State Road, Nancy’s and Offshore Ale Company are already saving all their shellfish shell for Jess to pick up.

Because restaurants’ shells come from off-Island water bodies (Cape Cod, the West Coast, even Canada) and could carry foreign micro organism or parasites, it would be unsafe for our local ecosystem to put them back directly in our ponds. They have to be aged, washed by rain and bleached by the sun at the Edgartown old landfill for a whole year before they are returned to the ponds to serve as subtrate for a new generation of Martha’s Vineyard wild oysters.

The project is starting small, but Jess hopes it will expand with volunteers, more restaurants getting on board, and maybe, next year, some shell recycling drop boxes for home cooks. For more information, contact: (508) 560-2993.