BOSTON – The rubber bands that bind lobster claws in Massachusetts are now about more than protecting people from their dinner. They’re also about protecting whales.

Beginning this weekend, lobsters caught off the state’s coast will have green bands on their claws stamped with “Massachusetts” and an image of a whale tail. It’s part of a campaign to highlight how state lobstermen are trying to make the seas safer for whales.

Massachusetts is the first, and so far only, state to require lobstermen to connect traps with rope that sinks to the ocean floor instead of lines that float and pose a danger to whales.

“Other areas fight these mandates. We want the public to know not all fishermen are in that category,” said Bernie Feeney, a 60-year-old lobsterman in Boston. “We’re ahead of the game. We’re hoping it appeals to people.”

The green band campaign is being led by environmental groups, including Ocean Conservancy, and the state Division of Marine Fisheries.

Lobsters are caught in traps strung together by the dozens and attached to buoys on each end. Whale advocates say when floating lines are used to connect the traps, it creates arcs of rope between them that can entangle whales.

Marine line entanglement is the second-leading human cause of right whale deaths behind ship strikes. At least 75 endangered whales died due to fishing gear entanglements between 1997 and 2005, including at least 16 North Atlantic right whales, according to federal statistics. Each death is a blow to a right whale population that numbers only 350 to 400.

It’s tough to prove that using the sinking rope makes a difference. Entangled whales are difficult to track, and when a whale is found dead from entanglement, the gear often can’t be traced to its source.

But it’s common sense that removing the floating rope hazard reduces the risk, said Regina Asmutis-Silvia of the Whale and Dolphin Conservation Society. The green band campaign gives customers a way to support that choice, she said.

Massachusetts’ sinking rope mandate, in effect in state waters since January 2007, was costly for individual fishermen: Feeney said he spent about $11,000 on the new rope and other required gear changes.

The sinking rope soon will be required by federal regulators for many East Coast lobstermen and other fishermen who use traps, though Maine has resisted the rule. The state is by far New England’s lobster leader with $297 million in lobster revenues in 2006 compared with $52 million in second-place Massachusetts.

Maine lobstermen say the sinking rope doesn’t work on their rocky ocean bottom because it wears out more quickly and gets easily snagged. They also say the right whale, the focus of conservation efforts, is rarely seen in Maine coastal waters, unlike in Massachusetts.

Federal regulators have proposed a six-month delay – to April 2009 – in its sinking line requirement, and Patrice McCarron, executive director of the Maine Lobstermen’s Association, said she hoped that gives Maine time to get state waters exempted.

She said Massachusetts’ green band implies other lobstermen aren’t as concerned with conservation, even though Massachusetts’ solutions for the whales wouldn’t work in Maine.

“I don’t have a problem with Massachusetts saying, ‘We’re doing a great thing,’ because they are,” she said. “What I don’t like is the implication that other people are not.

“It would just be nice to see everybody saying, ‘We’re all in this together. We’re all trying to find our way through,'” she said.

Bill Adler, executive director of the Massachusetts Lobstermen’s Association, said the green bands were meant to promote Massachusetts’ efforts, not take a shot at other states.

But he added Maine is no stranger to pushing its product at the expense of competitors. Last summer, lobsters caught in the state were tagged as “Certified Maine Lobsters” so customers would know they weren’t buying “impostor lobsters” from other states.

The green bands should be appearing at seafood markets this weekend and will stay on Massachusetts lobsters after sinking lines are broadly required to highlight the state’s pioneering efforts, said Vicki Cornish of the Ocean Conservancy.

She added she’s hopeful green band success could prod other states to make waters whale-safer.

“It’s not the reason why we did it,” Cornish said. “But if it has that side benefit, then the whales are happy.”