February 28, 2020
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Harpswell seeks funding to study clam decline

Friends of Casco Bay | BDN
Friends of Casco Bay | BDN
A hatchery-reared soft-shell clam, before being exposed to acidic mud flat.

HARPSWELL, Maine — The town is looking for state assistance to study how to protect a resource embedded in Harpswell’s heritage.

Harpswell’s 4,000 acres of intertidal mud flats have long supported the soft-shell clam industry, which has consistently reported some of the highest landings in Maine.

Recent environmental shifts, however, have reduced an industry that used to support more than 50 full-time harvesters to a handful of 10 to 15 people who supplement their income with other part-time jobs.

Statewide, landings of soft-shell clams have declined from 40 million pounds in 1977 to just about 10 million pounds in 2014, according to data from the state Department of Marine Resources.

“The heritage of clamming in Harpswell is dying right before our eyes,” says a new project proposal, titled “Habitat Planning in a Changing World.”

The town is asking the Maine Coastal Program for a $44,000 grant to help support projects studying how local ocean acidification and a disease called neoplasia affect clam populations.

Preliminary survey work by Resource Access International, the town’s marine consultant, showed that while some of Harpswell’s clam flats have healthy levels of acidity, others read “well below optimal levels” for larval clam survival.

More acidic seawater means less calcium carbonate, the raw building material for shells, hindering a young clam’s ability to grow.

A recent report from the environmental group Friends of Casco Bay found that increasing global carbon dioxide concentrations and local nitrogen pollution are contributing to the acidification of mudflats in the region. That report finds a significant correlation between acidic flats and declining shellfish populations.

To find out just what that means for the town, “Harpswell requires a complete [acidity] survey of all traditionally productive soft-shell clam habitat,” the proposal says.

The proposed project would follow the same sampling methodology as the Friends of Casco Bay study.

The town also hopes to identify “hot spots” where neoplasia exists in clam populations, to create strategies to remove diseased clusters to try to limit the spread of infection.

Darcie Couture, lead scientist at Resource Access International, said according to some initial reports, “the epicenter of the neoplasia issue seems to be Harpswell.”

The town is already conducting projects to study the control of two other environmental factors: predation by invasive European green crabs and the loss of eelgrass meadows.

Possibly affected by two colder-than-usual winters, “green crabs are not looking to be a huge issue this year,” Couture said. “That gives us time to look at other issues impacting shellfish health.”

The grant proposal stresses that even as Resource Access International carries out data sampling and analysis, staff will collaborate with local shellfish harvesters on a monthly basis to review proposed study areas and discuss findings.

“These priorities were actually identified by harvesters in Harpswell,” Couture said. She added that local knowledge helps her to identify flats that are currently productive or used to be productive, an important comparison for identifying what is causing the population decline.

Couture said studying this issue is vital for the future of the industry and its management.

“This region of Maine lands about a quarter of all soft-shell clams in the state, which is worth millions of dollars amongst the towns that share this region,” she said.

If funded, the two projects would be carried out between August 2015 and December 2016.

Couture said the town should hear back from the Maine Coastal Program about selected projects sometime in June.


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