A couple of weeks ago, on a sunny March Sunday, a group of scientists, shellfish harvesters and town employees headed out on the mudflats to set up a mud-bound experiment — all in an effort to learn more about soft-shell clams, one of the state’s most valuable resources, ranking third behind lobsters and elvers. And Brunswick ranks at the top of all Maine towns for its number of harvesters and pounds harvested each year. Brunswick currently has 63 commercially licensed harvesters and 17 student harvesters, and the resource is valued in the millions of dollars.
Soft-shell clams (Mya arenaria) are the ones that you see harvesters out digging for in the intertidal. While Brunswick may seem like it doesn’t have much coastline, there are actually over 61 miles of coast and 1,600 acres of intertidal in our town. The soft-shell clams live underneath the mud and use their siphons to pull in water from above, from which they filter out tiny bits of food. Clam harvesters have to wait for the tide to go out to make their way out onto the flats, look for their tell-tale siphon holes and dig them up using a clam rake. Then they are enjoyed by many Mainers and others further afield, often as steamers or as fried clams.
In recent years, however, several factors have caused a decline in the soft-shell clam population. Since 1975, the population has declined by 75%. The warming of waters and changes in water chemistry are thought to be one of those factors, as clams depend on the right components in the water to build their shells as they grow. And the growth in the population of the invasive green crab, Carcinus maenus, which loves to crunch through the soft shells of soft-shell clams, has also caused a significant decline.
This has all led to an interest in finding out more about the reasons for their decline and identifying potential solutions to protect the remaining population and rebuild the resource. If you want to increase the number of an animal, you of course have to focus on its reproduction, and there is currently a surprising lack of knowledge about the fecundity (the reproductive capacity of an individual or population) of soft-shell clams.
To answer some of those questions, the Downeast Institute — a marine-research laboratory and education center based in Beals, Maine, but that does research and education work throughout the state — applied for and received funding from a Saltonstall-Kennedy Grant, one of many projects funded this year to study various aspects of to U.S. fisheries. DEI is studying soft-shell clam fecundity in three regions (Downeast, Midcoast and southwest) along the coast, working with the towns in those regions to do the work over two spawning seasons, April through August 2023 and 2024.
Brunswick’s shellfish harvesters were offered conservation points, something they are required to earn a certain number of each year as part of maintaining their municipal shellfish license in Brunswick. Other options to earn points include participating in coastal clean-ups and attending meetings of the Marine Resource Committee. Opportunities like this one are unique and offer a way for harvesters to directly impact the resource and participate in the research regarding the shellfish populations in town. Five harvesters from Brunswick joined town staff and a team of scientists from the Downeast Institute to set up the experiment off Pennellville Road in Barnes Cove in Middle Bay.
The group set up a series of holding boxes in the intertidal from which they will take a sample of an assortment of sizes every week. Then, those samples will be taken to DEI’s lab where they will be subjected to high temperatures designed to induce spawning. The results will provide valuable information to managers about when and where clams spawn, how long into their lives they spawn and what size clams’ eggs have the best survivability. This will help managers as they consider options to restore the populations, including the possibility of increasing the minimum size of harvestable clams, having a maximum size limit and creating closed areas for spawning clams.
So, next time you’re out in Pennellville, take a look out on the flats and see if you see a series of boxes. Those are the ones being tested to see what we can learn about the reproductive lives of soft-shell clams and how that might positively impact the town’s resource.
Susan Olcott is the director of operations at Maine Coast Fishermen’s Association.
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