There was concern that the incident could have been connected to naval exercise activity involving high powered sonar and the Irish government pressed the UK on the issue:
NATO exercise activity has been associated with substantial loss of marine mammals before not least the infamous event in Kyle of Durness in 2011 when the UK MOD were forced to admit that the disposal of exercise ordnance had caused the beaching of 19 pilot whales (link):
The concern with the Autumn 2018 Whale UME (Unusual Mortality Event) is that because it involved Cuvier whales most of the fatalities would not wash ashore. As Irish Whale and Dolphin Watch stated at the time:
“Between Ireland, Scotland and Iceland around 80 Cuvier’s beaked whale strandings have been reported. If we use the figure from French studies of the proportion of bycaught dolphins that make landfall and are recorded by stranding schemes (8%) then up to 1,000 individual whales may have died. Indeed the % recorded stranded of those dying could be much lower as Cuvier’s are distributed much further offshore than the dolphins bycaught in the French study and more whales may sink at sea and not make landfall. So if Cuvier’s only occur in their low thousands and hundreds may have died through this UME, then we have a serious conservation issue, as this would have major impacts at population level. Of course these figures are open to much criticism, but it does demonstrate the potential seriousness of this UME.” (http://www.iwdg.ie/news/?id=2758)
The journal ‘Scientific America’ outlined the impact of sonar and set out the decibels levels that occurs:
“Unfortunately for many whales, dolphins and other marine life, the use of underwater sonar (short for sound navigation and ranging) can lead to injury and even death. Sonar systems—first developed by the U.S. Navy to detect enemy submarines—generate slow-rolling sound waves topping out at around 235 decibels; the world’s loudest rock bands top out at only 130. These sound waves can travel for hundreds of miles under water, and can retain an intensity of 140 decibels as far as 300 miles from their source.
“These rolling walls of noise are no doubt too much for some marine wildlife. While little is known about any direct physiological effects of sonar waves on marine species, evidence shows that whales will swim hundreds of miles, rapidly change their depth (sometime leading to bleeding from the eyes and ears), and even beach themselves to get away from the sounds of sonar.”
The Royal Navy say their sonar used in exercise is not injurious to Whales and other marine mammals but the ‘Scientific America’ article would seem to make that claim fatuous.
It is to be hoped the Irish government will press the UK further and publish the conclusions of the promised report.
Assistant General Secretary