Saltwater Farming: Oysters

by: Elizabeth Clemente

photography by: Nicole Harnishfeger

At first glance, the white building at the edge of Brant Point looks like any other harborfront structure. But inside, more than 50 million new lives are brewing.

For shellfish biologist Tara Reilly and assistant biologist Leah Cabral, the Brant Point shellfish hatchery is home base for projects aimed at supplementing the shellfish population on Nantucket, particularly bay scallops and oysters. The facility is equipped with specially-controlled tanks that mimic ideal conditions for shellfish propagation and the algae necessary to feed the shellfish, and was renovated last year.

Leah Cabral empties shells onto the reef.

The laboratory’s recent renovation has allowed the biologists’ long-term projects to go the extra mile, and Reilly said this year, armed with new equipment, they are hopeful to accomplish as much progress as was made in the past five years at the old hatchery. Both scientists’ projects, while designed to be proactive solutions to the decrease in island shellfish, are also intimately tied to water-quality issues in Nantucket Harbor.


Currently in its eighth year, Reilly’s bay-scallop larval-release program strives to fortify the species that has been directly affected by long-term degradation of eelgrass.

“The idea is to produce as many bay-scallop larvae as possible and release them during the spring and summer months, and allow them to grow naturally and feed off of the natural food in the harbor,” Reilly said.

The shellfish biologist said the program’s best year yielded 170 million bay scallop larvae, and so far this year she and her team have released 130 million, with roughly a month left of hatchery production for the fish this season.

Eelgrass is essential to the scallops’ life cycle because they attach to the plant when they are small, and it gives them protection from natural predators in the harbor until they grow bigger. The grass also holds the scallops in one spot so they can thrive naturally.

“In the winter time, particularly in Nantucket, we have a lot of heavy winds and scallops are really vulnerable to stranding on the shore,” Reilly said.

If the eelgrass is not as robust due to poor water quality and other factors, it cannot act as an adequate habitat for the bay scallops. Reilly said she and her team conduct surveys to determine what kind of plants and animals might be already living in areas where they release the larvae, and consult island fishermen with knowledge of the harbor bottom to get more information.


Cabral’s work with oysters, which are also cultivated at the Brant Point facility, is directed at restoring their numbers on-island, providing a place for research and improving water quality at the same time. The assistant biologist has been spearheading a pilot shell-recycling program for the past three years, working in conjunction with 30 island restaurants and raw bars and the Nantucket Department of Public Works.

The goal of the recycling project is to create a one-acre oyster reef, which Cabral successfully installed this spring in Shimmo Creek. After the shells were collected from restaurants, they were left to dry out for at least a year at the Madaket landfill in order to be guaranteed free of any meat. If the shells were placed back into the water with meat still on them, they could potentially infect the next generation of oysters and surrounding sea life with foreign diseases.

“Oyster larvae is chemically attracted to oyster shell, so they need that suitable substrate to attach to in order to metamorphasize into adults,” Cabral said. “That’s why our shell-recycling programs are so important, because we’re collecting a limited resource and then putting it back in the water for the larvae to attach to.”

While the shells were curing, Cabral spent a year securing permits to install the reef, as well as scouting potential sites around the island, doing oyster-growth studies and water-quality sampling. Though the degradation of eelgrass is ultimately a detriment to the underwater ecosystem, Cabral said it was helpful in choosing Shimmo Creek as the location for the reef, because the state Division of Marine Fisheries requires reefs to be installed in areas that are void of habitat.

“This is perfect for a restoration project, and it’s away from harbor users so there’s not a lot of boat traffic in there,” Cabral said.

Worldwide, oysters have declined by 85 percent, with the northeastern United States only having about 6 percent of its historic population remaining, due to a variety of factors including poor water quality and disease. Another contributor to oyster decline is people neglecting to put

suitable substrate for larvae to attach to back in the water, which Cabral said she thinks is especially an issue on Nantucket.

A single oyster has the ability to filter between 30 and 50 gallons of water a day, removing nitrogen from the water and eating algae, which clears the environment to allow light to filter through and promote eelgrass growth. A shellfish reef like the one Cabral is building can also protect against erosion, acting as a barrier for waves to break on before hitting land, and change the sediment in the area to allow for the proliferation of other organisms such as hard clams. Cabral’s reef is designed to be 10 rows of shells and nine rows of bare bottom, with the bare bottom leaving room for eelgrass and other fauna growth.

“There’s just tons of benefits of oysters, and restoration projects have been happening all over the coastal United States as well as worldwide, because their populations are so low and they have such important benefits to the water,” Cabral said.

Cabral’s reef is relatively small compared to some other projects around the world, which span hundreds of acres. As time goes on and Cabral installs the other half of the reef, she said she has plans to do dive surveys to measure oyster growth and understand how many oysters are growing there independently, as the eventual goal is for the reef to be self-sustaining.

An additional step in the coming years will be to decide if the area should be designated as a sanctuary, meaning it would be closed to shellfishing and protected as an area for scientists and students to conduct research. To close the area to fishing permanently, Cabral would need to petition the Division of Marine Fisheries and bring the issue before the town’s Board of Selectmen.


On the other end of the oyster-growing spectrum are island oyster farmers like Chuckie Connors, founder of Great Harbor Oysters, who currently has an aquaculture lease to grow oysters in up to 10 acres of the harbor. Currently, Connors said roughly six acres of the area is producing oysters, bringing his grand total to about a million shellfish. Even with the high numbers of seed deposited, oysters have a high mortality rate. Last season Connors lost between 500,000 and 600,000 oysters.

For farmers like Connors, the biggest waterquality-related issue is blooms of brown algae, also known as red tide, which can contaminate the shellfish and shut down the farms for extended periods of time. Connors said this season he has not had any significant problems with the invasive algae, but he has also not had any explicit discussions about his crops’ water-cleaning abilities.

“I haven’t spoken to anyone about it (but) with 5 million oysters I guess I can say I’m one of the people that helps the harbor the most,” he said.

“I think they do good things for the water in

Nantucket Harbor, generate some income on the island, (and) employ some people, so it’s all around good.”

At Topper’s restaurant at the Wauwinet inn, chef Kyle Zachary exclusively serves oysters harvested by Retsyo Oysters, another oyster farm operating in island waters. Zachary said he was curious when farmer Andy Roberts approached him about selling the shellfish three years ago, and wanted to try them for himself before making any promises.

Roberts launched Retsyo (oyster spelled backwards) in July 2011 after more than 25 years of harvesting Nantucket bay scallops in the winter months and fishing for conch during the summer.

“I was really surprised by them,” Zachary said. “I feel like they’re one of the best oysters I’ve ever had.”

The Retsyo oyster farm is located approximately 300 yards from the Wauwinet dock, and Zachary said the restaurant is proud to be able to support the island’s local fisheries.

“Oysters are a lot like grapes. Like when we start talking about wine, the oysters take on the environment in which they’re grown,” he said. “(Retsyo oysters) are super-clean, not too briny. A lot of the oysters that are grown on the bottom tend to be a little more briny (and) salty, (but) these are very, very clean.”

Cabral’s oyster reef is also supported by local businesses on-island, through her collaboration with a wine company called Proud Pour, which supports oyster reefs and bee habitats across the country depending on where patrons buy it. Multiple stores on Nantucket carry the company’s Sauvignon Blanc called “The Oyster,” which restores 100 oysters to Cabral’s reef for every bottle sold.

“Their slogan is ‘cheers to change,’ so you’re drinking to help the environment basically, which is pretty cool,” Cabral said. “So that’s nice, people are helping the reef. They’re eating oysters here, and that shell is then being put back in the water, and then if they’re drinking wine that is also putting oysters back.”

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