When oysters or mussels are being cultured, they hang around or stay put on the bottom. They can be found where a grower leaves them. But razor clams (Ensis directus) pose a different challenge. They like to travel. They can dig, swim or jump, skills they have honed to escape predators or to relocate to a more luxurious sediment. They are finicky about that sediment. Not too silty, not too sharp, they prefer fine to medium sand in a low intertidal or a subtidal location with moderate, possibly dynamic water flow.
So if razor clams are such prima donnas, why would a shellfish grower like Jesse Leach, who has a thriving oyster farm on the Bagaduce River, want to try to develop technology to keep them happy and raise them to market size?
One reason is diversification. Because they are relatively easy to culture and can grow to market size in about two years, they are considered a good candidate for promoting diversity in New England shellfish aquaculture, an important consideration for the survival and growth of the industry. As Paul Rawson, professor at University of Maine School of Marine Sciences, pointed out at a workshop on razor clam culture, a catastrophic loss or environmental change could wipe out a farm that depends on a single species.
Razor clams are also appealing as an alternative because they can bring about 25 to 40 cents apiece on the live market and are becoming increasingly popular. They’ve been recently featured in a Food Network show; “The New York Times” has featured recipes for razor clams; and the Trattoria Athena in Brunswick, Maine serves them roasted whole in their shell.
To further understand why Leach and other growers attended the workshop on razor clam culture organized in May by Dana Morse of Maine Sea Grant, one needs to consider that they are the artists, tinkerers, architects and engineers of aquaculture—the folks who will use chewing gum and baling wire, household and industrial containers, kids’ toys and swimming pools—any useful gizmo they can find to keep the costs down while developing the technology that works. Would they want to take up the challenge of razor clams? No doubt about it.
You could almost hear the wheels turning as Leach listened to presentations by Rawson and Dale Leavitt of Roger Williams University on their research with razor clam culture and their goals in a new project funded by the Northeast Regional Aquaculture Center (NRAC). Leach was not only considering the technology discussed and its possible modifications, but also various methods he has observed while visiting the “boneyards” of shellfish growers up and down the East Coast. (“Boneyards,” he explained, are those heaps of failed equipment behind a grower’s garage. He emphasized that even though they failed in one place, it didn’t mean they might not be useful in another.)
In 2001, Dale Leavitt and three other researchers were awarded a grant by the NRAC as part of an initiative to help the Northeast shellfish industry diversify with the culture of additional species. For three years, they explored methods of raising seed and encouraged nine growers from different areas to develop a growout technology that would contain the razor clams and provide protection from predators.
Leavitt says the hatchery phase of the research went well during the first year and they were able to give each grower between 10,000 and 15,000 seed. These were planted in low intertidal and subtidal containers, including bottom netted raceways, bottom cages, bottom tents, floating trays and bottom nursery trays and boarded raceways. The latter two were the most successful.
The second year and third years, they lost almost all of the seed due to problems in the early, post-set stage in the hatcheries, but seed from their first year was still out in the field, “growing like weeds.” Leavitt now believes one of their mistakes was not using sand for post-larval set.
Some of the juvenile clams were lost in growout. If too much silt built up in a wire cage holding the clams, the clams swam out through the holes in the top of the cage. On Cape Cod, clams did well at first, but died in August of the second year, most likely victims of high temperatures. In Rhode Island and Barnstable, Mass, the clams disappeared. “My guess is the sediment type wasn’t right for them and they got up and left,” says Leavitt, but at Martha’s Vineyard, clams in bottom trays had grown up to three and a half inches. “There’s no question they can be raised to market size (generally 3 to 4 inches) in two years,” Leavitt says.
Rawson, Morse, Leavitt and Diane Murphy of Woods Hole Sea Grant have won a $93,616 grant from NRAC to solve the problems encountered in the hatchery early post set. In Maine, Rawson will work with Mick Devin, shellfish hatchery manager at Darling Marine Center, to determine optimal hatchery and culture technology. They and the other researchers aim to produce one million juvenile razor clams in 2012.
These will be made available for growout trials in Northeastern states. A second workshop will review previously successful techniques, discuss other possibilities and help growers get started.
“Will the seed be ready by September?” Leach wanted to know. Rawson hopes so, but meanwhile, besides using their Yankee ingenuity to come up with growout techniques, growers will need to find suitable locations and figure out the permitting/leasing requirements. The latter is complicated because presently, the streamlined Limited Purpose Aquaculture license (one-year, no more than 400 square feet) does not include razor clams as an approved species and cannot be in the areas razor clams prefer.
“There’s a lot of work to be done to make razor clam culture a reality,” Morse says, but despite the challenges, people who have worked with razor clams believe they are a strong candidate for diversification. Leavitt says he talked with buyers who told him they could move over 1,000 pounds of razor clams a day if they could be guaranteed a consistent supply.
Muriel Hendrix is a freelance contributor living in Bath.