HARPSWELL — Harpswell’s Quahog Bay may be closed to quahog harvesting until June 20 to allow the bay’s mudflats to stiffen and the quahog population to recover.

The town’s Marine Resources Committee requested the closure after harvesters reported a drop in the bay’s quahog population and that the mud had become too soft to dig effectively, according to Paul Plummer, Harpswell harbormaster and marine resource administrator.

“Members of the Marine Resource Committee evaluated the flats in Quahog Bay from late fall to now and had made a determination that the resource has declined within these areas. However, the biggest concern is the anoxic appearance of the mud,” Plummer said. “This is when the mudflats are harvested heavily, not giving the mud a chance to heal, killing the nutrients within it.”

David Wilson, chairman of the Harpswell marine resources committee, said about 80% of the mudflats in Quahog Bay appear anoxic — or lacking oxygen.

“We’re trying to give this mud a chance to stiffen back up,” said Wilson. “This closure is negatively going to impact everyone’s income, even mine … but it has to be done. The most important thing about this closure is it’ll allow the shell stock to spawn without being interrupted.”

“All the shells have dropped down into the mud because it has been turned so many times it has been turned into pudding,” said Scott Monroe, a quahog harvester and member of the marine resources committee. “We’re trying to slow it down at the least impactful time of the year. We don’t want to impact our summer harvest.”

There are 55 people with commercial shellfish licenses in Harpswell. Plummer said the closure only applies to quahog harvesting. Softshell clams, razor clams and oysters can still be harvested in Quahog Bay. Quahogs can still be harvested in other parts of Harpswell.

Barry Catlin, a commercial shellfish harvester, spoke in opposition to the closure Thursday, asking to see data showing how a closure would help quahog populations, especially when Quahog Bay is still open to softshell clam harvesting.

Dr. Marissa McMahan, a senior fisheries scientist at Manomet, an environmental research organization, said the state and municipalities have relatively little data on quahog populations, making it difficult to discern how quahog populations have changed in recent years.

“We know that quahog landings are increasing, but landings don’t tell you about ecological abundance, just the harvesting pressure,” said McMahan. “Towns like Harpswell are tasked with managing their shellfish resources without the data or tools necessary for that. Moving forward, we want to develop survey methodologies that would get a better handle on clam populations.”

According to a 2019 commercial landings report from the Maine Department of Marine Resources, quahogs account for less than 1% percent of Maine’s nearly $674 million seafood industry.

Regardless of the lack of population data, McMahan said any species will benefit from an untouched ecosystem.

“If people are going out onto the mud flats in the winter, any quahogs that are left behind are exposed to cold air temperatures, which could lead to a higher winter mortality,” said McMahan. “Anything that is allowing a resource lay undisturbed is only going to help.”

McMahan said ensuring winter mortality stays relatively low betters the quahog population’s chances of having a strong spawning season, which usually happens in the late summer when water temperatures are highest.

Harpswell selectmen unanimously approved the closure Thursday. During the closure, the marine resources committee will evaluate Quahog Bay every 60 days for signs of improvement. The town’s request will be reviewed for approval by the Maine Department of Marine Resources within 20 days.