Cape Cod Communities Gather Oyster Seed Grown in Dennis

DENNIS – A three-week project to grow oyster seed that will be used in coastal resiliency projects across Cape Cod came to a conclusion Friday as communities picked up their product.

The Aquaculture Research Corporation at Chapin Beach in Dennis grew the oysters on 3,500 bags of recycled shell that will be used by seven Cape Cod towns as oyster reefs.

The reefs will help provide water filtering capability, assist with erosion and protect low-lying areas.

Many public and not-for-profit groups have dedicated resources to expanding oyster reef building in their towns.

“We are setting 10,000 oysters per bag and then the towns will put them out in their restoration areas to reestablish oyster reefs around the region,” said Rob Doane, the Aquaculture Research Corporation CEO.

The process involves loading the bags into two large tanks, filling the tanks with seawater and then introducing oyster larvae into the tanks.

Over the course of three weeks, the larvae attach themselves to the shell in the bags.

That’s when towns pick them up and take them to their coastal waters.

The towns of Mashpee, Bourne, Wareham and Barnstable are among the towns taking part.

Historic wild populations of shellfish and oysters are at one percent of normal levels.

“That has a lot to do with over harvesting going back to the 19th century and before as well as the degradation of our water quality in the more recent history,” Doane said.

Water quality in the region is poor due to excess nitrogen from law fertilizer or lack of functioning septic systems. The nitrogen is getting into coastal embayments and creating nutrients for algae to thrive.

The high algae levels gather at the surface of the water which prevents sunlight from penetrating to help eel grass grow.

The project will add oysters into the system to consume microalgae.

“By simply existing an oyster is taking away that excess algae from the water,” Doane said.

“And a single oyster can filter 40 gallons of water per day.”

Through the ARC project, 36 million oysters will be added to local waters this year.

“All those oysters will help mitigate the problems of excess algae or nitrogen in the water,” Doane said.

The project compliments other efforts being taken across Cape Cod communities, such as sewer systems, to stop nitrogen from getting into the water.

The ARC has been conducting this project for the last 14 years. They also provide towns in the region with clam, quahog and oyster seed used for commercial and recreational shellfishing beds.

The oysters are spawned in-house. They are brought up to the point of metamorphosis and then they are placed into the tanks with the bags of recycled shells and they spend the next few weeks growing to a size where they are viable to be put out into the marine environments.

Individual oysters can expect to survive up to five years or longer in the wild.

“As they get older, unfortunately, they are more susceptible to environmental conditions such as shellfish disease and water quality issues,” Doane said.

When the oysters go through metamorphosis they produce an adhesive, comparable to a drop of cement.

“They take that drop of cement and stick to some kind of substrate, and in the case of an oyster reef it’s another oyster that has been there for a previous generation,” Doane said. “They keep building on top of each other year after year and that is how the oyster reef grows.”

The ARC is using recycled shells from processing plants or restaurants that have been cleaned of any old bacteria or protein.

“We’ve really created an ideal environment for them to attach to these shells,” Doane said. “And they are permanently there for their entire life.”


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