PORTLAND, Maine (AP) — A rare whale found dead off Massachusetts earlier this year died as a result of entanglement in Maine lobster fishing gear, federal authorities said.

The North Atlantic right whale was found dead off Martha’s Vineyard in January. The whales are declining in population and are at the center of efforts to more tightly regulate shipping and commercial fishing off the East Coast.

A necropsy determined that the whale died from “chronic entanglement” in gear that was earlier determined to be consistent with the kind of rope used in Maine’s lobster fishery, the National Oceanic and Atmospheric Administration said Wednesday. NOAA said a law enforcement investigation into the whale’s death remains open.

The right whales number less than 360 and they have experienced high mortality in recent years. The death of the whale reignited a longstanding debate between environmentalists and commercial fishermen about the need to more tightly regulate lobster fishing.

The right whales, which can weigh 150,000 pounds (68,000 kilograms), are vulnerable to lethal entanglement in the ropes commonly used in lobster fishing that connect lobster traps to surface buoys.

“Dying this way is a horrendous fate that no creature deserves, but it’ll happen again and again until we get these deadly fishing ropes out of the water,” said Kristen Monsell, oceans legal director for the Center for Biological Diversity.

Members of the industry said Thursday they have made strides to avoid the whales and have largely succeeded. The vast majority of America’s lobster catch comes to the docks in Maine, where the seafood is a cultural icon and a key component of the economy. The state’s lobster catch was worth more than $460 million at the docks last year.

“The fact is we know that entanglement in Maine gear is extremely rare. This is the first reported entanglement of a right whale in Maine lobster gear in 20 years and the first death attributed to the fishery,” the Maine Lobstermen’s Association said in a statement. “Maine lobstermen have made significant changes to how they fish over the last 25 years to avoid entanglement.”

The population of the whales fell by about 25% from 2010 to 2020. They were once abundant off the East Coast, but they were decimated during the commercial whaling era and have been slow to recover.

The whales’ migration has become dangerous in recent years because their food sources appear to be moving as waters warm, scientists have said. Scientists and environmentalists have said the whales stray from protected areas of ocean and become vulnerable to entanglements and collisions.