PORTLAND — A new minimum legal size for lobsters has taken effect in federal waters, but Maine, Massachusetts and New Hampshire aren’t enforcing the measure, heeding the objections of lobstermen and dealers.

U.S. officials said Thursday that the minimum legal size for lobsters had been increased, as scheduled, from 3 1/4 inches to 3 9/32 inches from the base of the crustacean’s eye socket to the end of its body where the tail begins.

The new minimum size covers lobsters caught in so-called federal waters, from three miles off the coast to 200 miles out. When the new rule took effect Tuesday, it became illegal to ship any lobsters larger than the federally mandated size from one state to another.

But officials in Maine, Massachusetts and New Hampshire said Thursday they’re not going along with the increase in state waters, which run from the coast to three miles out, because of objections from the lobster industry.

“It’s verging on a mess right now,” said Dick Roe, regional director for the National Marine Fisheries Service. “It should be resolved one way or another.”

Many lobstermen and lobster dealers in New England have opposed increasing the minimum size any further because they contend it puts them at a competitive disadvantage against their Canadian counterparts. Canadian lobstermen are allowed to keep and sell smaller lobsters.

“We’re losing our foreign trade markets to the Canadians right now,” said Herb Hodgkins, president of the Maine Lobster Pound Owners Association. “We’re passing it to them on a platter. The foreign markets, Europe and Japan, want the smaller lobsters, but we can’t supply them.”

The New England Fishery Management Council, a quasi-government agency that oversees the region’s fishing industry, has refused to back off on its plan for increasing the minimum lobster size in increments as a conservation measure.

Under that plan, the minimum legal size of lobsters increased in 1988, 1989 and again on Jan. 1 of this year. The legal size is scheduled to be increased one more time, on Jan. 1, 1992, to 3 5/16 inches.

Many biologists contend the increases are needed to prevent New England’s lobster population from being decimated by overfishing.

Patricia Fiorelli, a spokeswoman for the fisheries council, said the group seemed to be standing firm in its decision to stick with the scheduled increases.

“They’ve voted on it two or three times in the last year and they’ve always voted to stay with the increase,” she said. “They’ve always felt the lobster fishery is heavily exploited and these gauge increases were needed to protect the lobster resource.”

But lobstermen have enjoyed record-high harvests over the past two years and many argue there is an abundance of lobsters, making such conservation measures unnecessary.

Maine’s congressional delegation had appealed to U.S. Commerce Secretary Robert Mosbacher to delay the latest increase, but he declined to use his power to do so, said Roddy Mocoso, a spokesman for the National Marine Fisheries Service in Washington.

Officials in Massachusetts and New Hampshire said Thursday, however, that their states are going to keep the minimum size at the existing level of 3 1/4 inches in state waters.

In Maine, the federal limit automatically took effect in state waters. But Marine Resources Commissioner William Brennan said he expects the state Legislature will adopt a bill proposed by the lobster industry to keep the minimum size at 3 1/4 inches.

In the meantime, Brennan said, state officials are giving Maine lobstermen and dealers a grace period — meaning they aren’t enforcing the new minimum size — until the Legislature addresses the issue.

Brennan said he expects the fisheries council’s lobster oversight committee to vote Friday on recommending that the full council agree to postpone the latest increase for one year.

“Because Maine and Massachusetts together produce 80 percent of the lobsters in the United States, I feel quite confident that ultimately the feds will go along with that,” Brennan said.

Ed Blackmore, president of the Maine Lobstermen’s Association, agreed, saying, “I’m sure it’s going to be changed.”

Until then, Blackmore predicted the discrepancy between federal and state laws wouldn’t cause many problems for fishermen or dealers. “They can’t come out and say they’re not going to enforce the law, but I think it’ll be a ho-hum enforcement.”