Environmental campaigns have maintained for years that sonar systems used by shipping leads to the stranding of whales.
But now international research has confirmed their concerns for the first time that whales strand themselves on beaches when they are lost and disorientated by high-frequency underwater noise.
An independent scientific review panel found the systems, mainly used for underwater mapping, were responsible for the mass stranding of 100 melon-headed whales in Madagascar in 2008.
Teams from the Wildlife Conservation Society (WCS) and International Fund for Animal Welfare (IFAW) were able to rescue some of the whales, but it was too late for many of them.
While aspects of the stranding in Madagascar remain unknown, the panel concluded that a multi-beam echosounder system, operated intermittently by a survey vessel moving down the shelf-break the day before the event was the most ‘plausible and likely behavioral trigger for the animals initially entering the lagoon system.’
There are now concerns about the impact of noise on marine mammals as the systems are commonly used by many industries.
A report commissioned by the panel said: ‘The potential for behavioural responses and indirect injury or mortality from the use of similar MBES [multi-beam echosounder systems] should be considered in future environmental assessments, operational planning and regulatory decisions.’
The noise from the high-frequency sonar systems, used by the military, shipping and research vessels, can cause the animals to swim into the wrong areas, and it is thought that use of the system leads to beachings in the UK too.
Every year 800 whales, dolphins and porpoises to be stranded on British beaches, although it is not known whether sonar systems are to blame.
Dr Howard Rosenbaum, director of the Ocean Giants Program for WCS, welcomed the report and said: ‘These conclusions add to a mounting body of evidence of the potential impacts of anthropogenic noise on marine mammals.
‘Implications go well beyond industry, as these sonar systems are widely used aboard military and research vessels for generating more precise bathymetry (underwater mapping).
‘We now hope that these results will be used by industry, regulatory authorities and others to minimise risks and to better protect marine life, especially marine mammal species that are particularly sensitive to increasing ocean noise from human activities.
Katie Moore, director of animal rescue at IFAW said: ‘Mass stranding response is challenging under the best of circumstances.
‘Together with local individuals and the government of Madagascar, we provided the expertise to rescue as many animals as possible and medical care to those that stranded alive.
‘Equally important was to gather as much data as possible from the animals to address the root cause of the stranding. We are pleased to see the ISRP report and its conclusions, which will hopefully be used in shaping future conservation policies.’
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