Since June 7, six North Atlantic right whales have been found dead, floating in the Gulf of St. Lawrence, in a loss that amounts to more than one per cent of the population of the endangered species.

The whales were all found in the area between New Brunswick's Miscou Island, Quebec's Magdalen Islands and northern P.E.I.

While there have been sightings of dead right whales in the area before, Tonya Wimmer, a marine biologist and the director of Marine Animal Response Society, said it's on a different scale this time around. The charitable organization is dedicated to rescue and study of marine animals.

"It's a bit of an unprecedented event in that we've never had an incident like this involving right whales where so many animals have been turning up dead just over the last few weeks," said Wimmer.

Department of Fisheries and Oceans Canada (DFO) estimates the global population of the right whale is approximately 500. This means the dead whales account for a little over one per cent of the species. To put that into context, if one per cent of humans were to die, that would be over 75 million people.

"The loss of even one animal is huge with animals with a population this small. Basically, every animal counts," said Wimmer.

​At least two of the whales were females, which is even more devastating to the species.

A red triangle represents the approximate area where all the whales were found. (Google Maps)

"We're not just losing her, you're losing every baby she could have [throughout] her lifespan," said Wimmer.

"That could be five, 10 animals."

There is no known cause of death for the right whales and no obvious possibilities.

"There's nothing on them. There doesn't seem to be anything apparent from the outside," said Wimmer.

There is no indication yet of the cause of death for the whales. (Marine Animal Response Society)

Cathy Merriman, a species-at-risk biologist at DFO said no conclusions can be drawn from the deaths until a necropsy is performed, which is essentially an autopsy for animals.

"The only way to determine that for sure, or even to rule out certain causes of death, that can only be done by a close forensic examination," said Merriman.

"It's an incredibly messy and unpleasant thing to do."

Necropsy challenges

Merriman said since the right whale is an endangered species, performing a necropsy is "a very high priority."

However, there is no timetable for the necropsy because it is a mammoth undertaking. One of the whales would have to be towed to shore and the weather has been too bad to do that.

There are also other possible complications.

Researchers from the Marine Animal Response Society examine one of the dead right whales. (Marine Animal Response Society)

"Towing for more than 30 kilometres, the whale could simply disintegrate. The tail could fall off and the whale could sink," said Marc LeCouffe, the director of resources for DFO.

He said the number of dead whales could grow, noting there have been other sighting reports, but they may be the same whale.

DFO is asking that if anyone sees a dead, injured or entangled marine mammal to call the Marine Animal Response Society at 1-866-567-6277.