SOREL (AFP) - A young humpback whale found dead in waters near Montreal only days after delighting Canadians likely died this week in a "boat strike", the examining vet said on Wednesday (June 10).

"The preliminary diagnosis is a suspected boat strike," said Dr Stephane Lair, a University of Montreal veterinarian leading a post-mortem examination of the two- to three-year-old female that weighed 17 tonnes and was 10m long.

The ocean giant's breaches against the backdrop of Montreal drew hundreds to the Old Port neighbourhood of Canada's second-largest city for a glimpse of the first of this species to swim so far up a Canadian river.

But its carcass was spotted early on Tuesday by a passing commercial ship, two days after it was last seen alive.

It was dragged to the shores of the Saint Lawrence river near the town of Sainte-Anne-de-Sorel, about 80km east of Montreal, and lifted onto shore with the help of a crane.

"The whale shows signs of trauma, that is to say there were hematomas and hemorrhages which strongly suggest that the animal was struck by a boat," said Dr Lair.

A full report is expected to be made public in a month or two.

The analysis, notably of internal organs, will be "fairly limited", however, due to the body's "fairly advanced state of decomposition", Dr Lair said.

"We don't know what happened," said Mr Robert Michaud, of the Quebec Emergency Network for Marine Mammals, an association mandated by the Canadian government to protect cetaceans in the Saint Lawrence seaway.Humpback whale found dead in River Thames east of London

"We knew it was a healthy animal with no chronic disease problems," he said.

He added that it was not unusual for young whales to explore beyond their usual habitat.

The Montreal visitor was likely led astray while chasing prey, or made a navigation error when it swam 400km inland.

Dr Lair said he hoped the magnificent animal's visit would be fondly remembered and give rise to more ocean conservation.

He noted that humpback whales were no longer an "endangered" species and that "the population has experienced a fairly significant rebound in recent decades".

"The more humpback whales there are in the wild, the more likely they are to have negative interactions," he said.

"But that may be proof that the population is increasing."