Only 450 of the baleen whales are now estimated to remain, and 17 of these are said to have died in the past year alone, mostly in Canadian and US waters.

Boat-strikes and entanglement in fishing-gear are blamed at least in part for the deaths among the right whale (Eubalaena glacialis) population.

The scale of the fatalities has been severe enough for the US National Oceanic & Atmospheric Administration (NOAA) to declare them an “unusual mortality event”.

Autopsies have been conducted on 11 of the dead whales found this year, though the final results have yet to be published.

With females dying off faster than males, and only around 100 breeding females left, 2017 was reported to be a poor reproductive year for North Atlantic right whales, reducing the chances of rebuilding the population. A right-whale pregnancy takes a full year, and the weaning of calves another.

NOAA believes that the whales may be coming to harm after being forced out of protected areas in search of food, and says there is evidence that trauma caused to individuals that survive entanglements could be affecting their reproductive ability.

NOAA has asked members of the public to help by reporting any sightings of dead whales or live ones stranded or otherwise in distress.

Meanwhile, an independent team of scientists is being assembled to review the existing data, sample whales found stranded in future and come up with effective means of protecting the species.

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