Harpswell selectmen unanimously approved a grant-funded project aimed at restoring eelgrass in three coves by replacing boat moorings.
Harbormaster Paul Plummer said 20 privately-owned boat moorings that use traditional block-and-chain moorings, which can tear and uproot eelgrass when the moorings are dragged along the ocean floor, will be replaced with conservation moorings.
Conservation moorings, screw into the ocean floor and use an elastic line, minimizing contact with the ocean floor, which does less damage to underwater vegetation like eelgrass.
That swap could restore nearly 9,000 square feet of subtidal eelgrass in Curtis Cove, Dipper Cove and Stover’s Cove.
“The idea behind this project is to study the effectiveness of helical moorings on eelgrass beds and see if the eelgrass grows back in and fix what the traditional moorings do by scarring the ocean bottom,” said Plummer.
Plummer said the three coves were chosen because they have both eelgrass beds a high number of moorings.
“We were worried that if we chose an area that only had four moorings, maybe only one would agree to change their moorings and we’d have to go to another cove,” said Plummer.
Boat owners in the selected coves aren’t required to change their moorings, but Plummer said it would benefit those who volunteer because “I would call it a free upgrade, and the grant even covers replacement parts over the next five years.”
Harpswell has 2,344 registered moorings scattered across the town’s 216 miles of coastline – the most of any Maine community – but fewer than 15 of those moorings are conservation moorings, said Plummer.
“With over 200 miles of coastline, there’s a lot that needs to be managed in that area,” said Town Administrator Kristi Eiane. “We think this is a worthy program to be a part of.”
The effort will be funded by a $234,000 grant awarded through the Maine Natural Resources Conservation Program, administered by The Nature Conservancy on behalf of the Maine Department of Environmental Protection and the U.S. Army Corps of Engineers. The grant requires no match from the town.
Plummer said the town will replace the boat moorings in June and July and study how changing the moorings impacts eelgrass through 2027.
Underwater meadows of eelgrass provide a habitat for shellfish to spawn, stabilize shorelines, mitigate erosion and combats climate change by absorbing greenhouse gasses, according to the Maine Department of Marine Resources.
Plummer said it takes years to properly study eelgrass because “the eelgrass will come and go.”
“In places that it has been historically, you may not see it for three or four years and then that fifth year, it’ll come in out of nowhere,” said Plummer. “We need to give it enough time to study the effectiveness.”
It’s also in shellfish harvesters’ best interest to restore eelgrass beds in their area because the health of plant directly impacts the strength of future shellfish harvests, said Plummer.
“Eelgrass provides a habitat to our young invertebrates like lobsters and clams to hide from predators,” said Plummer. “If the eelgrass is unhealthy, these animals don’t have anywhere to hide and grow, and that can play a big role in future harvests of those species.”
Plummer said Harpswell’s eelgrass beds seem to be bouncing back nearly a decade after green crabs wreaked havoc on the plants. Green crabs are an invasive species that eat baby lobster and soft-shelled clams and destroys eelgrass as it hunts for food.
“Back in 2013 and 2014 when the green crabs came in heavily, they took a toll on our eelgrass beds,” said Plummer. “Now that the number of green crabs has reduced, our eelgrass seems to be coming back.”
Green crabs are native to Western Europe and first came to the U.S. as stowaways in the ballasts of ships. According to a 2015 report from the Governor’s Task Force on the Invasive European Green Crab, the species was first seen on the Maine coast in 1905.
The green crab population grew exponentially in the 1950s, subsided, then reappeared with a vengeance in 2012 and have been an issue for fishermen ever since. During its three-year life cycle, a single green crab can leave behind 370,000 offspring.
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