Carcass of blue whale, an endangered species, found drifting in St. Lawrence Estuary

Marine biologists in Quebec are hoping to learn more about what caused the recent death of a blue whale, an increasingly rare and endangered species.

The whale's carcass was spotted several times by a crew fishing near Mont-Louis in the Gaspé region at the end of October.

At first, it was believed to be a Minke whale, a smaller, more common variety of rorqual whale.

But when marine biologists saw a photo of the animal about a month later, they realized it was a blue whale — probably a very young one.

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'Any loss is … a bad loss'

Robert Michaud, a marine biologist and co-ordinator of the Marine Mammal Emergency Network in Tadoussac, explained that only small portion of a blue whale carcass shows when it floats in water.

They usually drift belly up, making them difficult to identify, he said, adding that a full-grown Minke whale is about the same size as a baby blue whale.

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The World Wildlife Fund estimates there are between 10,000 and 25,000 blue whales left on the planet.

Marine biologist Richard Sears said when it comes to blue whale deaths, it's hard to say definitively whether losing a baby is worse than losing an adult.

"We've seen so few calves in the last 38 years — only 23, in fact, on this side of the Atlantic — that to lose a young animal that is part of replenishing the population would not be good," Sears said.

"Any loss from the population of blue whales is a bad loss."

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How did whale die?

The calf's carcass was found in a shipping lane, which could mean it was hit by a large vessel.

"The problem is there are no overt, evident marks on the carcass, but that doesn't mean anything because when a whale is struck, sometimes you see very little marks on them and most of the damage is done inside," Sears said.

Michaud said the marine industry is collaborating with biologists in Quebec to reduce the risk of collisions, such as having vessels lower their speed when travelling through areas where whales are known to congregate. 

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He said the whale carcass is probably still drifting. Because it took so long to identify it as a blue whale, they missed the opportunity to use data to predict its path.

Biologists will have to wait to see if the carcass washes ashore in order to conduct a necropsy and learn more about how the whale calf died.