Whales may have suffered from ‘the bends’ before dying off Irish coast

Five recorded strandings of the deep-diving species causes concern

A stranded Cuvier’s beaked whale on Gola Island, off Co Donegal. Photograph: Donegal Irish Whale and Dolphin Group/Facebook

The British or US navies could be responsible for the deaths of five Cuvier’s beaked whales off the north-west coast of Ireland in recent days, according to the Irish Whale and Dolphin Group (IWDG).

According to the group, there have been five recorded strandings of the whales between Friday, August 3rd and Tuesday, August 7th, which is “definitely cause for concern”.

Spokesman Dr Simon Berrow said the deep-diving species, normally found more than 50km offshore, were sensitive to acoustic disturbance such as naval sonar.

The Irish navy does not have sonar capabilities, but both the UK's Royal Navy and the US Navy have such equipment, he told RTÉ's Morning Ireland.


Dr Berrow explained that loud underwater man-made noise, such as sonar, would prompt Cuvier’s beaked whales to surface too quickly. They could then experience “the bends” [decompression sickness] and die.

The last time a similar instance occurred was in 2014, around the same time as military exercises were taking place, he said. “Both the British and US navies have active sonar that has been used in Irish waters,” Dr Berrow said.

It is a matter of conjecture how the whales died, he said, but he thought that the use of sonar was a likely cause of death.

The IWDG received reports of three dead whales on Saturday, August 4th in Donegal and Mayo. One was in Sheephaven Bay, Co Donegal one on Gola Island and one at Tirraun on the Mullet Peninsula, Co Mayo.

All three whales appeared to have been dead for several days and were in similarly poor condition, suggesting the possibility that all three had died around the same time.

Dr Berrow said that the poor condition of the dead whales meant that post mortems could not be carried out to determine the exact cause of death.