Butter Clams: A New Species Diversifies the Aquaculture Roster on Cape Cod
A butter clam is just a juvenile surf clam.
Surf clams are the big, wide clams Cape Cod cooks chop up and use for chowder or clam strips. In Asia people use the tongues for sushi, and lots of beachcombers collect the shells to use as soap dishes or ashtrays. But those are full-grown surf clams and they all come from a wild fishery.
M: Wild surf clams you’ll find in deeper waters off shore, the wild fishery dredges for them, and they have to be 5 inches long at that point. When we grow them in an aquaculture environment, butter clams at this 1 and 1/2-2 inch size, are a new opportunity in Massachusetts. In 2016, the Massachusetts Division of marine Fisheries made it legal to grow and harvest aquaculture butter clams.
That’s when Melissa and Jen saw an opportunity.
M: We are collaborating with the Aquacultural Research Corporation, the Cape Cod Cooperative Extension, and Roger Williams University to look at how we can create alternative species here on the Cape for aquaculture growers. And this really came out of demand from the industry for something else to grow. 99% of the shellfish that we grow in MA are oysters and quahogs and that leaves them open to really catastrophic losses. If there’s disease or warming waters or a harmful algal bloom, something that impacts their business they could lose an entire season. So working with surf clams gives an opportunity to diversify what they’re growing.
Historically, Atlantic surf clams have done best in the warmer waters off of New Jersey. Growth rates depend on temperature—surf clams south and north of this mid-Atlantic sweet spot have traditionally grow significantly slower—in some places taking up to four years to reach full size where the New Jersey clams took only three months.
M: Researchers have been seeing the entire population start to shift northwards as the waters have been warming, so this clam creates an opportunity to proactively adjust for warming waters.
Right now on the Cape, surf clam seed grows to butter clam size in a year or two. Melissa and Jen and their students are testing different grow out methods—growing them in deep water in bags on racks, burying them on the flats and covering them with mesh, or laying them on the bottom in fine mesh bags. They hope that in the next year or so butter clam cultivation will catch on. In the meantime, they’ve been bringing them to chefs to try out.
J: For the most part it’s been very positive. They’re really easy to work with, they’re very uniform when they’re cooked, and their taste is a little less like low tide, which seems to be for the most part pretty positive for everyone.
E: And so what are people doing with them?
J: There’s your traditional dish like linguine with white clam sauce, some people have done an incredible riff with a fermented black bean sauce, and avocado poured over these clams—
M: We had a chef that just steamed them up put them with some tomatoes and red pepper flakes. I took some home and just cooked them up like steamers, put them with some butter and beer in a pot and I cooked them up and they were fantastic.
Traditional aquaculture clams—littlenecks and cherrystones—aren’t growing as fast here on the Cape as they used to. Researchers aren’t sure why—it could be warming waters or poor genetic breeding or even a lack of food in the water. Whatever the reason, there’s much more demand for local clams than there is supply.
J: And that’s part of this project as well is to find out whether chefs and restaurants would pay the same price for this product as they would for other products that fishermen have access to.
In the meantime the Cape Cod Cooperative Extension and other researchers like Jen Bender and Melissa Sanderson are continuing to explore new species as our waters change.
This piece first aired in August, 2017.