The death of a sixth North Atlantic right whale has members of the whale community feeling overwhelmed, according to a leading researcher.

Philip Hamilton, a research scientist with the Anderson Cabot Centre at the New England Aquarium, said the news of another dead whale was difficult to take.

"It's really devastating for me and the rest of the right whale community to hear of yet another one," said Hamilton.

Hamilton said he hasn't seen the photo of the latest dead whale, so the aquarium hasn't been able to identify it.

The latest dead right whale was found floating off Quebec's Gaspé Peninsula. It was the fourth dead whale found in 48 hours.

It has been a deadly year for right whales. Hamilton said he fears it could be worse than it looks.

The whale researcher said it's possible that more whales have died, but haven't been discovered yet.

"We know historically we only discover a portion of the dead whales," he said.

"We know that by whales that are sick or entangled or even healthy whales that just disappear and we don't see them for 20 years … I am concerned that we probably haven't seen them all."

'Clearly ... not enough'

On Thursday, Transport Canada implemented interim, precautionary speed restrictions in two shipping lanes in the western Gulf of St. Lawrence.

Ships 20 metres or more in length will now have to travel no more than 10 knots in the area.

The department had already established that speed limit in a larger portion of the gulf in April.

Philip Hamilton, a research scientist at the New England Aquarium, fears that more whales have died, but haven't been discovered. (Matthew Bingley/CBC)

While Hamilton applauds the quick action from the Canadian government, he said the restrictions that have been imposed don't go far enough.

"It clearly is not enough," said Hamilton.

"We need to start having a bolder, more aggressive approach to management that will actually protect these animals."

Necropsy on 3rd whale

A necropsy on the third dead right whale will start Friday in Norway, P.E.I.

The whale was found on Tuesday, drifting off the coast of the Acadian Peninsula.

The date, location and cause of the whale's death are unknown.

There are believed to be approximately 413 North Atlantic right whales left in the world.

No right whales were recorded dying in Canadian waters last year, but 12 were found dead in the Gulf of St. Lawrence in 2017.