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Shellfish Aquaculture in Massachusetts
September 2000

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Shellfish aquaculture in Massachusetts is thriving! Though centuries old, the practice of farming shellfish is a fairly recent undertaking in the United States -- within the last 150 years.

In Massachusetts, shellfish aquaculture can be divided into two categories: public and private. Public aquaculture, also known as community or municipal aquaculture, focuses on local restocking and/or restoration efforts in areas that are or once were productive shellfishing areas. Such programs generally fall under the auspices of town shellfish constables. Municipal aquaculture programs raise clams, oysters, and/or scallops to a size that they can be released into the wild with a reduced risk of mortality from predation. At the appropriate size threshold, the shellfish are seeded into productive fishing areas to support local wild harvests, both commercial and recreational.

Private aquaculture involves licensing tracts of marine intertidal and subtidal areas for private use to grow a variety of commercial shellfish species, including quahogs and oysters. Local shellfish hatchery and nursery businesses often support public and private aquaculture operations and municipal restoration programs.

Nursery trays are commonly used during the early stages of shellfish culture. Shown here, trays holding seed quahogs in Blackfish Creek, Wellfleet. Photo by Dale Leavitt.

Current Production

Production of farmed shellfish in Massachusetts has been expanding steadily over the past 10 years as the number of towns, farmers, and areas licensed for culture have increased. Of the $4.6 million total value for cultured shellfish production in Massachusetts in 1996, quahogs account for the vast majority, at $3.8 million, while oysters make up the difference, at $0.8 million. Since 1996, the number of private aquaculture permits for shellfish culture has increased from about 250 to over 300, while the areas privately licensed for culture has increased from 600 acres to over 1,000 acres. Greater than 95 percent of this culture area is located on intertidal and subtidal flats within two counties of southeastern Massachusetts: Barnstable (Cape Cod), and Dukes (Martha’s Vineyard).

While shellfish aquaculture is experiencing significant growth, commercial harvest of wild quahogs and oysters in Massachusetts has remained fairly flat, hovering at the $5.5 million mark for the past ten years. Of this, Cape Cod harvests account for approximately $3.1 million, while Martha’s Vineyard harvests provide an additional $0.55 million, together accounting for nearly two-thirds of the total harvest in Massachusetts. In terms of the recreational fishery for quahogs and oysters, figures are more difficult to come by, mostly because recreational harvesters do not have to report their catch -- other than an estimate -- when renewing their licenses. Despite the lack of harvest data, recreational quahog and oyster fisheries are a very important component to the way of life in southeastern Massachusetts.

Town shellfish departments on Cape Cod and Martha’s Vineyard are committed to public aquaculture of hard clams and other shellfish species for the purpose of stocking shellfish for wild harvest. In 1999, with funding from the Massachusetts Division of Marine Fisheries, distributed by Barnstable County, all fifteen towns on Cape Cod collectively purchased 20 million juvenile quahog seed from commercial hatcheries as part of their municipal restocking programs.

On Martha’s Vineyard, the Martha’s Vineyard Shellfish Group (MVSG), a consortium
of Island towns dedicated to producing shellfish seed in a hatchery, provided 11 million quahog seed, four million oyster seed, and six million juvenile bay scallops to the six island towns in the program. These juvenile bivalves will be released into the wild fishery after nursery culture within each town’s municipal shellfish nursery program. In addition, the MVSG provided one million seed oysters to private growers on the Island that are participating in a fishermen’s retraining program administered by the MVSG.

Current Culture Practices

Massachusetts has two shellfish hatcheries that pro-duce a wide variety of seed shellfish, including American oysters, quahogs, bay scallops, soft shell clams, and surf clams. One hatchery is a commercial enterprise, Aquaculture Research Corporation (ARC), located in Dennis, MA. ARC has been at the forefront of shellfish hatchery technology and production for over thirty years. MVSG is the second Massachusetts hatchery and has been operational since 1978. Unlike a commercial hatchery, the goal of MVSG is to supply the public shellfish propagation programs on the island with quahogs, oysters, and bay scallops. Both hatcheries are proven success stories.

The nursery stage of both quahog and oyster farming involves the use of trays: a bottom tray system on Cape Cod, and a raft-based tray system on Martha’s Vineyard. In both methods, growers purchase small seed (1-3mm) and plant it into shallow trays (4–8 inches deep and usually 32-square feet in size) in late spring (June). Private quahog growers harvest the seed stock in October, or once quahogs reach approximately 15mm in size. They are then planted under netting for the final grow-out stage. Town shellfish restocking programs take a different approach: seed remains in nursery trays throughout the winter until it reaches approximately 25mm in size. This generally occurs by spring, at which point the seed is planted directly into the wild.

A recent WHOI Sea Grant Extension Program/Cape Cod Cooperative Extension effort involves assisting with the development of upwelling nurseries in Massachusetts. Upweller technology allows growers to purchase smaller, less expensive seed and grow it in a protected environment (the upweller) until it is ready for the field nursery (late summer) or direct grow-out planting (fall). For the final grow-out stage, most growers plant on the bottom and cover the crop with a fine mesh net to exclude surface predators.