Another right whale that had been entangled in fishing gear in the Gulf of St. Lawrence — where six of them died last month — has been freed.

Officers with Fisheries and Oceans Canada were able to disentangle the whale, which had been caught up in fishing gear north of Prince Edward Island, east of the Magdalen Islands, on Wednesday.

Kim Davies, a researcher in Dalhousie University's oceanography department, told CBC News the whale had recently become entangled.

"They were able to free the animal and there was also an aerial survey in the area and the aerial survey located that whale, gear-free. So a happy ending to that particular story," said Davies. 

Last month, six whales died in the gulf. With only 525 North Atlantic right whales remaining, according to the Marine Animal Response Society, the recent "unprecedented die-off" represents more than one per cent of the population.

Whales killed in separate events

One of the three whales examined last week was tangled in fishing gear. Two others showed signs of trauma from ship collisions, but it's not clear whether those collisions happened before or after the animals died. Necropsies are unlikely to be performed on the three remaining dead whales.

"Those animals are in an advanced state of decomposition and they're far from shore so there are no firm plans right now to bring any of those animals to shore to do any more necropsies at this time," Davies said.

Right whale necropsy in Norway, P.E.I., June 29, 2017

The necropsy of a right whale requires not just a large crew, but also heavy equipment. (Marine Animal Response Society)

The whales died at different times and were found in various stages of decomposition.

"[That] suggests there was more than one event, that they were not all kind of in a group that was struck by a ship at once but there were several different mortality events," Davies said.

Right whales changing feeding areas

Right whales have changed their feeding areas in recent years.

There have been fewer sightings in traditional feeding grounds in the Bay of Fundy and southwest Nova Scotia, Davies said.

"In 2010, scientists in the Gulf of Maine as well as in Canada started to see significantly fewer sightings in those areas and a decline in the number of calves which suggests there is a food shortage," she said.

"That was when we started looking elsewhere."

Right whale freed in Gulf of St. Lawrence

The Campobello Whale Rescue Team cut the fishing lines away from the entangled right whale on Wednesday. With only 525 North Atlantic right whales remaining, according to the Marine Animal Response Society, the recent 'unprecedented die-off' represents more than one per cent of the population. (Canadian Whale Institute/Anderson Cabot Center for Ocean Life)

In 2015, observers started noticing more right whales in the Gulf of St. Lawrence between the Magdalen Islands and the Gaspé Peninsula.

Davies said that is a problem because unlike the Bay of Fundy, high-traffic shipping areas in the Gulf of St. Lawrence don't have precautions in place to protect the critically endangered creatures.   

There is also a lot of fishing gear in the Gulf of St. Lawrence, she added. 

Right whales, alive and dead, are tracked from research ships as well as by planes with the help of the National Oceanic and Atmospheric Administration. Whales are also tracked using a listening device attached to an autonomous underwater glider that listens for the distinct call of right whales, Davies said. 

Part of her research involves a drone which surfaces every few hours to transmit right whale sounds to her lab. 

"That helps to fill gaps when the ships and the aerial surveys, which need good weather and daylight, when they can't monitor," she said.

With files from CBC's Information Morning