HALIFAX -- An endangered North Atlantic right whale has been freed after getting entangled in fishing gear near the area where six other whales were found dead.

Tonya Wimmer of the Marine Animal Response Society said the large whale was cut free of the fishing line in its mouth after it was spotted by an aerial surveillance plane in the Gulf of St. Lawrence on Wednesday afternoon.

"It's a good news story ... thank goodness," said Kim Davies of Dalhousie University's Department of Oceanography. "It was disentangled pretty readily -- they didn't have to chase it over multiple days."

The whale didn't appear to have been snarled in the mess of gear for very long, and appeared to not have suffered serious injuries, Davies said.

A research ship was nearby and marine mammal experts were able to free the whale within six hours of it being spotted.

The discovery comes after six of the massive animals were found floating in the gulf, with two suffering injuries consistent with ship strikes and a third dying from an entanglement in fishing gear.

One of the six dead whales has now drifted close to shore on the Magdalen Islands. Wimmer said they are discussing sending a team to do an animal autopsy to determine its cause of death, as had been done in three others.

"It seems very clear that there definitely are a lot of right whales that are using that habitat ... they're definitely encountering the gear that obviously is in that area," Wimmer said.

Researchers have identified 90 individual whales this year in the Gulf of St. Lawrence, Davies said, and they appear to be crossing shipping lanes.

"We have fairly good evidence ... that there's probably more whales in the gulf now than there has been, and these entanglements and ship strikes are not isolated events," she said. "There's been a few different events now."

Three right whales were found dead in the southern gulf in 2015, although none were necropsied, she said.

There are no conservation management initiatives for right whales in the Gulf of St. Lawrence "because we've only known they've been there for three years," Davies said.

Measures have been taken elsewhere in the Maritimes to minimize contact between shipping traffic and whales, and Davies said she expects similar measures will be discussed in the gulf.

"There are speed restriction options, there's re-routing options, there's adaptive management options, so I think we're going to see all that put on the table now," she said.

Among the possibilities: Acoustic monitoring for whales, so ships can be alerted in real time that they are present, as currently happens in the Boston area.