PORTLAND – The sense of frustration could be seen on their faces, heard in their voices and read on their T-shirts.

Commercial fishermen who have been stewing for months over proposed North Atlantic conservation measures had a public forum for their grievances at a meeting held by the New England Fishery Management Council on Thursday.

The council presented data showing that the total number of cod, flounder, haddock and other groundfish species have increased threefold since 1994. But some species have shown little growth, and the overall rate of increase has not been fast enough to satisfy the requirements of federal law.

Those details are hard to swallow for fishermen who feel their livelihoods are threatened. Estimates are that up to 3,000 jobs could be lost along the Northeast coast because of the new rules.

“Why not let it keep working the way it is?” asked Richie Walker, who owns two fishing boats on Vinalhaven. “It’s not failing now.”

Demaree DiBiase, who has a small lobster boat on Cousins Island in Yarmouth, wore a T-shirt in support of groundfishermen that read “Change the law.”

That hope is remote, as there appears to be little support for a change in the law outside the Northeast. So the fishery council faces a November deadline to recommend one of four proposals on the table to federal regulators.

The alternatives, contained inside a 1,600-page draft document known as Amendment 13, include cutting fishing days at sea by as much as 65 percent and imposing strict quotas on protected species.

That last option has received the coldest reception at a series of public meetings around the Northeast, said Frank Blount, a council member.

By May, the National Marine Fisheries Service must implement measures that satisfy a federal law mandating the restoration of each species within 10 years.

The Portland meeting drew an overflow crowd of about 150 people, including fishermen, workers at seafood processors, city officials and a variety of curious onlookers.

Blount subtly reminded the worried fishermen not to kill the messenger. But the irritation they were feeling was clear even before the public comment period began.

Terry Alexander of Cundys Harbor said he had 262 fishing days at sea when he started in 1995, and now that number is down to 104.

“And they want to take 65 percent of them,” he said. “They’ve taken all of our options away.”

Blount seemed to understand that emotions run high when the inheritors of a 400-year-old way of life feel besieged.