BOSTON – An environmental group hoping to strengthen protections for rare right whales has asked the federal government to expand the whale’s breeding and living areas that are shielded by the Endangered Species Act.

The National Marine Fisheries Service last week said it would consider a petition by the Ocean Conservancy to expand so-called “critical habitats” in New England waters and off the southeastern coast, where North Atlantic right whales live.

The critical habitat designation recognizes an area as vital to an endangered species. It doesn’t guarantee tighter restrictions for fishermen, shippers or others who share the waters with whales, though some fear that would result.

“They’re going to bleed this for all it’s worth,” said Gary Ostrom, vice president of the Massachusetts Lobstermen’s Association.

NMFS spokesman George Liles said if the petition is approved, the fisheries service will review existing rules, and could make changes.

The petition is open to public comment. NMFS must make a final decision by next July.

There are only 300 to 350 North Atlantic right whales remaining, and five died this year. Ship strikes and fishing gear entanglements are frequent causes of whale deaths. Restrictions to protect whales include closed fishing areas when the whales are nearby, reduced ship speeds and the use of special fishing gear that breaks if a whale is caught.

Under the Ocean Conservancy petition, the water between existing critical habitat areas in Cape Cod Bay and the Great South Channel would also be labeled a critical habitat, as would additional areas running about 10 miles north and 110 miles east of Provincetown.

Off the coast of Georgia and Florida, where the whales breed, the plan would add roughly 2,700 square nautical miles to the whale habitat.

Much of the proposed new critical habitat areas already have restrictions to protect the whales under the Marine Mammal Protection Act.

But those restrictions can be abandoned relatively easily, while rules adopted under the Endangered Species Act are tougher because they must remain in place until the whales are out of danger, said Nina Young of the Ocean Conservancy.

Expanding the habitat designation also recognizes new science that shows the whales move in a much broader area than first thought, she said.

“It’s not a case of an evil environmental group coming down and looking for more regulations,” Young said.

Young said the Ocean Conservancy would continue to work with the Atlantic Large Whale Take Reduction Team, a groups of scientists, fisherman and conservationists that recommends measures to prevent whale deaths.

Ostrom, a member of the take-reduction team, said naming certain areas critical habitats is folly because whales live all over the ocean. Expanding the designating areas is just a way to expand the reach of regulation, he said, adding he doubted environment groups intend to negotiate changes.