Three 1,000lb bombs detonated underwater by the Royal Navy were to blame for the mass stranding and deaths of a pod of pilot whales on the north coast of Scotland in 2011, it has emerged.
A report released by the Department for Environment Food and Rural Affairs on Wednesday cited the explosions as a significant factor in the whales' deaths.
The resulting noise damaged their sensitive hearing and navigational ability, causing confusion amongst the pod, and resulting in them accidentally travelling towards the beach where they ultimately died.
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The report relates to events which took place on 22nd July 2011, when 70 long-finned pilot whales in the Garvie Island Bombing Range, Cape Wrath, were exposed to the effects of bomb detonations in the sea near the Royal Navy's Northern Diving Group.
Despite attempts by experts to save the 39 whales left stranded, 19 ended up dead.
Cape Wrath is owned by the Ministry of Defence and large parts are used as a military bombardment range.
"The magnitude, frequency and proximity of the multiple detonations in the day prior to the stranding, and the single high order detonation shortly after the beginning of the mass standing were plausible sources of significant disturbance to any neighbouring marine mammals."
Loud noises can damage the hair cells in the ears of whales vital for detecting pressure changes, leaving them “functionally deaf”, the report points out.
“Long-finned pilot whales are known to follow other members of the pod and appear to spook relatively easily.”
The report criticises the Royal Navy’s visual checks for whales before bombs are exploded as “insufficient”, and recommends improved monitoring. It also highlights the routine use of devices elsewhere in the world that burn out rather than detonate bombs.
The MoD said that it accepted the findings of the report. “It identified a number of possible factors that may have influenced events, one of which was the detonation of underwater explosives,” said a spokesman.
“The recommendations will be considered by the MoD and implemented where appropriate. Additional mitigation has already been put in place during munitions disposal activities conducted since 2011.”