When it comes to clams, does size really matter? One Maine scientist is on a quest to find out.
Concerned for the future of the state’s second most valuable fishery, Brian Beal, a marine ecology professor at the University of Maine at Machias and the director of research at Downeast Institute, is embarking on a study to determine if large soft shell clams produce more eggs than their smaller counterparts.
If, like lobsters, jumbo clams do spawn exponentially more eggs, it could justify taking another look at statewide conservation measures to preserve the dwindling number of clams along Maine’s coast.
“The clam fishery is in trouble in Maine,” said Dianne Tilton, the head of the Downeast Institute, which learned earlier this month that the federal government would fund the study. “[This work] could encourage the industry to put an upper size limit to help productivity on the flats.”
The technical term for what Beal is exploring is fecundity, or the ability to produce offspring. Little is known about the fecundity of clams, but Beal suspects that the bigger the clam, the larger the number of eggs.
He also plans to look into whether egg production is influenced by where clams are in the tidal flats and where they are along the Maine coast.
“No one’s really addressed the question of fecundity in terms of size, in terms of tidal height, in terms of region of the coast,” Beal said.
For some animals, getting older and larger can eventually hinder reproduction. Take humans, for instance.
“Not many 80-year olds are having babies,” Beal said.
For other species, the bigger the better. Lobsters and sea urchins both produce exponentially more eggs the larger they get and have legal protections that force fishermen to throw them back if they’re caught above a certain size.
There have been attempts to implement something similar for clams, but they never had solid scientific backing. In 2017, a bill proposed a 4-inch maximum size limit on clams, as well as dropping the existing 2-inch minimum size to 1.5 inches.
The measure failed after coming up against opposition from clammers, seafood dealers and the Department of Marine Resources, largely for the lower minimum. In 2019, the state passed a bill that allowed local municipalities to enact stricter regulations on minimum and maximum clam size.
Gouldsboro was the first – and remains one of the few – in Maine to enact a 4-inch maximum size and has had buy-in from its local clammers, said Mike Pinkham, the town’s shellfish warden.
“It seemed logical that larger clams would produce more spat,” he said.
Clammers didn’t seem to mind because there isn’t as much of a demand for larger clams.
Beal’s study will involve taking clams from Brunswick, Bremen and Jonesport next spring and inducing them to spawn in a lab. He’ll then compare the number of eggs released by different sizes.
The research is happening as the clam fishery is shrinking. Maine’s clammers have landed less than 1.6 million pounds of clam meat annually for the last six years, something that only happened three times before between 1950 and 2015.
The species is threatened by predators that have come to New England with warming waters, chiefly green crabs and milky ribbon worms.
If the science proves that bigger clams produce more eggs, it could provide managers with more data to make decisions for the future of the fishery.
“It will be a valuable piece of information for the state of Maine and other states that have soft shell clams,” Beal said.