Plodding through Montsweag Bay mud last Friday, a group of 7th grade students from Woolwich Central School planted flower pots laced with clam seed in intertidal plots.

Brian Beal, a professor of marine ecology at the University of Maine in Machias and director of research at the Downeast Institute, organized the study at the request of the Woolwich Shellfish Conservation Committee.

“We’re buying some hatchery seed this fall,” said Tim LaRochelle, co-chairman of the committee. “This study will tell us where the best place is to put our seed.”

Clam seed, or hatchery seed, are juvenile clams about the size of a pinkie fingernail, said LaRochelle. Woolwich typically gets the seed from the town of West Bath in exchange for one third of the harvest.

The green crab invasion, however, has devastated harvests and nearly wiped out natural seed in the area, he added.

“We put the seed in here, but it was unprotected,” said LaRochelle. “We didn’t realize the green crabs were as prolific as they are, so a lot of that got fed on.

“The green crabs have eliminated most of our seed — we really haven’t had a good natural set in five or six years,” he continued.

Beal divided the students into two groups and directed them to place 12 clam seeds in each of 36 pots. The pots were then planted in six plots of six. In each plot, two pots — the control pots — are unprotected, two pots are covered with regular netting, and two pots are covered with extra heavy gauge netting.

“We also placed crab traps nearby yesterday,” said LaRochelle. “One of them had four crabs in it — last year, it would have been completely filled.”

The extreme cold temperatures of last winter appear to have taken a toll on the invasive green crab population, said LaRochelle, and the near empty crab trap is a promising sign for shellfish populations.

“Last year when we did a green crab study we hauled about 200 pounds of them,” said LaRochelle. “You’d pick the seaweed up and they’d be crawling everywhere.”

On the lookout all day, he said he had yet to see a single green crab outside of the traps.

“The extreme cold kills the crabs, like it did in the late 1960s, early 1970s when we had some cold winters,” said LaRochelle.

Having tried various conservation projects in the past, LaRochelle said having Beal — who has conducted research up and down the coast, including a recent study commissioned by the town of Freeport — is a boon to the committee and local economy.

The students who participated will return in the fall as 8th grade students to conclude the study, said LaRochelle, and the committee will then know the best places to plant their hatchery seed for a better harvest.

rgargiulo@timesrecord.com