Royal Navy bomb explosions ‘deafened and killed pilot whales’ according to a new report.
Scientists have concluded that four bombs detonated underwater by the Royal Navy were responsible for the deaths of 19 pilot whales that became stranded off the coast of northern of Scotland in 2011.
The report, published on Wednesday by the Department for Environment, Food and Rural Affairs (DEFRA) said the noise from the explosions was likely to have interfered with the whales hearing and navigation abilities, causing them to drift onto the beach and die.
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The Guardian reports:
On 22 July 2011, 70 long-finned pilot whales swam into the Kyle of Durness, a shallow tidal inlet east of Cape Wrath, Europe’s largest live bombing range. Despite attempts to herd them back out to sea, 39 were left stranded by the tide.
Concerted efforts by expert teams and local people managed to refloat 20, but 19 ended up dead. It was one of the largest mass strandings in recent years, and it prompted a government-funded investigation by 12 scientists from laboratories across the UK.
Their report reveals that three 1,000-pound bombs were detonated in the sea nearby by the Royal Navy’s Northern Diving Group in the 24 hours before the whales were stranded. A fourth 250-pound bomb was exploded after stranding began.
The bombs were left over from military exercises in which planes target Garvie Island, a small rocky outcrop 4.5km from the Kyle of Durness. Some bombs miss the island, fail to detonate and sink to the seabed, where they have to be located and disposed of for safety reasons.
“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 stranding, were plausible sources of significant disturbance to any neighbouring marine mammals,” the report says.
The three initial explosions could have had a “significant detrimental effect on the hearing and therefore navigational competence of any cetaceans in proximity,” it adds. The fourth bomb “might have served to drive the animals further inland”.
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.”
It 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.
“Given the potential damage to marine life from the high-order explosions of conventional disposal techniques, it is questionable why this method has not been used routinely in the past,” the report says.
The lead author of the report, Andrew Brownlow from Scottish Marine Animal Stranding Scheme at Scotland’s Rural College (SRUC) in Inverness, was pleased that it had “finally” been published. It was hard to be definitive about the causes of mass strandings, he said.
“However we have suggested mitigation strategies which will hopefully reduce the plausible risk from these types of high-energy detonations on marine life. It is hoped they will be taken on board.”
According to Sarah Dolman, Northeast Atlantic programme manager for Whale and Dolphin Conservation, it was “no coincidence” that the whales were stranded hours after the bombs were exploded.
She said: “Why has it taken four years to publish the report and what measures have the Ministry of Defence (MoD) put in place to evaluate and minimise the impacts of detonations around Garvie Island, to ensure that it adequately protects whales and dolphins since then?”
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.
In the US, Marine researchers have been speculating that man made noise pollution in the Pacific is responsible for driving whales to their deaths along Californian shores.