PLYMOUTH — With their traps piled high on the docks and buoys loaded in their trucks, lobstermen from across the South Shore gathered Thursday morning at the town dock here to protest extended fishing closures to protect right whales.
But hours later, officials at the state Division of Marine Fisheries lifted the ban on lobster traps in Cape Cod Bay, reversing an earlier decision to extend the closures until May 14.
The decision means commercial and recreational lobstermen may resume setting their traps in waters north and east of Cape Cod.
In an effort to protect right whales, which are among the most endangered species on the planet, state officials in recent years have banned the region’s lobstermen from fishing in Cape Cod Bay between Feb. 1 and May 1, when the large mammals feed on plankton there.
State fisheries officials on Monday decided to prolong the closure, which they have also extended in previous years, after more whales were spotted in the bay, including one of seven calves born this year. Recent plankton counts indicated the whales are likely to continue feeding there for some time.
“By extending the seasonal closure and speed restriction, the Division of Marine Fisheries aims to protect the right whales still present in Cape Cod Bay from entanglement and ship strikes,” said Katie Gronendyke, a spokeswoman for the agency.
In lifting the ban, state officials said the most recent aerial survey demonstrated that “right whales have migrated out of those state-waters adjacent to Cape Cod.”
The decision was announced hours after several lawmakers and local officials stood at the dock, and addressed scores of lobstermen, many of whom said they hadn’t received a paycheck in months.
“Hopefully this sends a message not only to our state regulators but to our federal regulators that something has to be done,” said state Senator Patrick O’Connor, a Republican who represents Plymouth.
State Representative Mathew J. Muratore, also a Republican who represents Plymouth, reiterated what many local fishermen say: There’s no evidence of right whales dying in the area from fishing entanglements.
“So what are we doing?” he asked.
But scientists and regulators say fishing lines pose the chief threat, particularly those that extend from buoys on the surface to lobster traps on the seafloor.
In a federal survey of right whale deaths between 2010 and 2014, scientists found that 82 percent died as a result of entanglements, which can drown them instantly or kill them slowly by making it exhausting to swim and impairing their ability to feed. The rest died from ship strikes.
There are just over 400 right whales left, with only about 100 breeding females. Last year, there were zero calves born, which was unprecedented, and the year before a record 17 whales were found dead. At that rate, scientists say, the whales could go extinct within 20 years.
Last month, a government-appointed team of federal and state regulators, fishermen, scientists, and others agreed to take major steps that aim to reduce the number of whale deaths and serious injuries by 60 percent.
The members of the Atlantic Large Whale Take Reduction Team recommended that the National Oceanic and Atmospheric Administration take steps to reduce as much as half the lobster lines in large portions of the Gulf of Maine, which stretches from Cape Cod to Nova Scotia.
The delegation from Massachusetts agreed to reduce the amount of so-called end lines by as much as 30 percent, while pledging that fishermen would use weaker rope that is more likely to break in the event of a whale entanglement.
At the rally in Plymouth, lobstermen protested that they’ve had to bear the brunt of the regulations to protect right whales, given the prolonged closures.
“This is economically devastating,” said Beth Casoni, executive director of the Massachusetts Lobstermen’s Association. “This is causing economic hardships on the many families that depend on the lobster industry.”
The lobstermen noted that the three months of official closures on the bay are really more like five months, given that it takes about a month for lobstermen to remove their traps and another month to put them back.
At 34, Dean Philip Karoblis, who fishes out of Sandwich, is one of the younger lobstermen trying to make ends meet. He said he’s not sure how long he can remain at the only profession he’s ever known, one passed down from his father.
“These new whale regulations are just crippling our way of life,” he said. “We don’t want to hurt whales. We need to be able to coexist. I need to be able to make money, and the whales need to be able to survive. We just want common-sense rules.”
Danny McDonald of the Globe Staff contributed to this story. David Abel can be reached at email@example.com.