Shucks may sound like an innocuous word, but to a clam it’s deadly serious. And folks on the Cranberry Isles are deadly serious about their clamming. Commercial diggers have wiped out the island clam beds from time to time. So at town meeting in March the Cranberry Isles enacted an ordinance that bars commercial clamming.

Town Clerk Frances Bartlett has already issued a dozen licenses to island residents. For each 10, under a Maine statute, a community must offer one license to a non-resident. The Cranberry ordinance is more generous, offering two non-resident licenses for the first 10. But commercial digging is prohibited. A “recreational” license costs $16 for residents, $31 for nonresidents, gratis for persons over 60 or under 13. It permits a person to dig up to one peck a day for use of himself and his family. Up to 10 percent can be under the legal minimum size of two inches.

Commercial clamming is thriving elsewhere, however, and many coastal towns in Hancock and Washington counties issue commercial licenses to their residents. Landings have been increasing in recent years, from a low point five or six years ago. Hal Winters, shellfish program manager for the Department of Marine Resources, says the ups and downs have historically followed a 30-year cycle. Last year the harvest totaled about 11 million pounds.

Mr. Winters says a few other towns in the two counties prohibit commercial digging as a conservation measure. The pattern is common in southern Maine, where resort communities want to reserve their clams for summer visitors. Ogunquit, which has a fine, productive clam bed, rules out commercial diggers. Its clams are so big and plentiful that they crowd out seed clams that could provide for the future. Mr. Winters has tried unsuccessfully to persuade the town to allow some commercial digging to thin out the bed and let a new crop get started.

Cranberry Islanders can continue to dig for clams, as they have for generations, but now they needn’t fear commercial competition. The clams are coming back, and they see no immediate need for reseeding. They can take a tip from the commercial clammers, however: Face uphill, away from the water. It’s easier on the back.