More than $350,000 worth of lobster gear has been damaged and lost since early summer in a bitter Down East trap war that’s being fought in the waters between Deer Isle and Mount Desert Island, prompting state marine patrol officials to offer a $15,000 reward for information that will help in their investigation.

“This trap war is without a doubt the most costly loss of gear I have witnessed in my 32-year career with the Maine Marine Patrol,” said Col. Jon Cornish of the Department of Marine Resources.

The vandalism began in early summer off Newbury Neck in Surry and has escalated in recent weeks, according to the agency’s commissioner, Patrick Keliher. As many as 15 lobstermen who haul traps along the line between two of the state’s lobster management zones are believed to be involved in the conflict, in which lobstermen cut the surface buoys marking a competitor’s traps. Keliher said he has approved overtime and additional vessels to work on the investigation.

Closing a lobster fishing zone because of a turf war would be unprecedented, but Keliher said he was prepared to take that step if necessary.

“I don’t want to take an action that could potentially penalize law-abiding harvesters,” he said, “but I am committed to preventing this from escalating even further.”

Three lobstermen already have been charged with “trap molesting” this year in other cases, said Jeff Nichols, director of communications for the marine resources agency. Two have had their licenses suspended, and one suspension is pending, he said. Trap molesting is a civil violation that may come with a fine ranging from $100 to $500.

The $15,000 reward is being put up by Operation Game Thief, a privately funded nonprofit that raises money for rewards offered in cooperation with state agencies. Last February, Operation Game Thief offered an $11,000 reward in a case where someone was raising traps near Jeffrey’s Ledge, in the western Gulf of Maine, that belonged to someone else. No charges have been filed in that case.

The territorial dispute is occurring along the line that separates Maine lobster zones B and C. Zone B extends from Schoodic Point to Newbury Neck, and Zone C stretches from Newbury Neck to Cape Rosier.

Patrice McCarron, executive director of the Maine Lobstermen’s Association, called the trap line cutting “an extremely significant enforcement issue.”

She said the group is glad that lobstermen can use the Operation Game Thief anonymous tip line to assist the investigation without jeopardizing the loss of any of their own gear.

“These are really tough issues for people to talk about because if they’re not involved, they don’t want to get their gear cut,” she said.

John Williams, a longtime lobsterman from Stonington, said he has fished the disputed area before, but doesn’t any longer. He wasn’t aware of the current escalation of troubles, but said trap wars have been going on there for probably 100 years. There are about 50 residents of Stonington who fish that area, he said, and about the same number from towns east of Stonington.

Williams, who had his trap lines cut about three decades ago, said the $15,000 reward is “a great idea.”

“It’s not a good feeling when you go out to haul your gear and it’s not there,” Williams said. “You may have a suspicion (about who did it), but what do you do?”

Williams said lobster traps cost about $100 each, so for a lobsterman who fishes a typical 800 traps, losing 200 of them is “a big deal.”

He said the lines that demarcate lobster management zones are supposed to be used for voting purposes – for example, how many traps can you fish in your zone? But over the years those voting lines have become “fishing lines.” He said he hopes the younger generation can be taught that “the person on the other side of the line is not your enemy.”

“It doesn’t solve any problems,” Williams said of the rampant trap line cutting. “I don’t understand the mentality of it, I really don’t.”

Anyone with information can call the Operation Game Thief Hotline at (800) 253-7887; out-of-state callers should dial 287-6057. Information also can be provided through an online tip reporting form.

CORRECTION: This story was updated at 7:49 a.m. on Nov. 1, 2016 to clarify trap molesting charges in other cases this year.