Grey seals to blame for deaths of porpoises washed up on coastlines

They are seen as the country’s friendliest sea creatures, with countless people flocking to the coast to glimpse them up close.

But, according to researchers, grey seals are responsible for the “traumatic” deaths of harbour porpoises washed up along the north and north-east coast after being bitten.

Scottish and Dutch scientists analysed the deaths of the creatures, two of which were found in the north-east. In a study led by researchers at Scotland’s Rural College, microbiologists, pathologists and ecologists worked to identify bacteria found in wounds on harbour porpoises stranded in Scotland, England, the Netherlands and Belgium.

They identified it as Neisseria animaloris (N. animaloris), which was previously linked to human infections following dog bites.

Killer whales were ruled out due to their lack of prevalence in the North Sea, as were species known in the area to act aggressively toward harbour porpoises, such as white-beaked dolphins, bottlenose dolphins and harbour seals.

Their findings show the marine animals were attacked by grey seals and died a slow and “traumatic” death. Lead researcher, Inverness-based microbiologist Geoff Foster, said: “We looked at the first four porpoises and wanted to pinpoint what exactly had happened.

“N. animaloris is commonly found in dogs’ mouths but we knew a dog couldn’t possibly catch a porpoise in the water.

“I had an initial theory that a grey seal was responsible – and this is what we proved with this research. The porpoises appear to have survived the initial assaults, only to die later of infections introduced from the mouths of seals during the attacks.”

This new study, published by Scientific Reports, has shown that porpoises which survive the initial attack may still die as a result of being bitten.