Fishermen spotted a minke whale carcass Thursday morning floating in the St. Lawrence River near Contrecoeur, Que., about 40 kilometres east of Montreal's Old Port.
It could be one of the two whales spotted swimming off the shores of Montreal earlier this month, but the Group for Research and Education on Marine Mammals (GREMM) must first examine the carcass to confirm, according to its director, Robert Michaud.
On May 9, Michaud confirmed that, for the second time in two years, a whale had been seen near Jean-Drapeau Park in Montreal, 450 kilometres upstream from its usual habitat.
Then, on May 11, a second minke whale was spotted in the St. Lawrence River and the two whales remained on either side of Île Sainte-Hélène for at least two days.
"These events are relatively rare but not exceptional. It does happen. Some animals, whales included, get lost," Michaud told CBC Montreal's Daybreak a couple of weeks ago as he discussed the high degree of risk the whales faced swimming in the river's fresh water.
For starters, they did not have access to their usual food found in the Gulf of St. Lawrence or the estuary — food not found in fresh water.
In addition, in fresh water, these cetaceans are exposed to pathogens that are not present in their natural habitat and against which they may not be able to defend themselves.
They are at risk of physiological disorders that can develop from long-term exposure to fresh water, he explained, and they can be invaded by algae as happened to the humpback whale two years ago. So the shorter the stay, the better the chance for survival.
There is also a risk of collision because there's quite a lot of traffic and the river is narrow, Michaud said. That is what experts suspect ultimately killed the humpback whale.
In the case of this dead whale, he said researchers will be able to better determine what happened once they examine the carcass.