Confirmation from the Ministry of Defence that military sonar was being used prior to a mass stranding of dolphins in Cornwall this year has renewed concerns that the intense noise emitted could have been the cause of the animals death. 
 
Responding to a Freedom of Information Request from WDCS, the Whale and Dolphin Conservation Society and other groups the Ministry of Defence has confirmed that military sonar was being used during the South Coast Naval Exercises until the day of the stranding. Up to 31 military vessels were involved in the exercises on the 4th and 5th of June. 

Sarah Dolman, WDCS noise campaigner said “Despite reports that the Navy had originally denied their ships were in the area, this information from the Government confirms that there was extensive activity in the days leading up to this terrible stranding.  Both dipping sonar and mid frequency sonar as well as other noise sources have been confirmed as in use during this exercise. We are still waiting for a full and timely investigation to be completed by the Government and we will continue to pursue this investigation until we get to the bottom of the tragedy”

Common dolphins are regularly seen off the South West coast of England, and the English Channel is known to be an important habitat for them.

The 26 common dolphins stranded on 9th June in what is the largest mass stranding of dolphins ever recorded in the UK. The majority were found near St Anthony, spread over almost 1km of the River Percuil, whilst single stranded animals were also found at Trelissick on the River Fal and at St Mawes. Initial results from post mortems found the animals had not fed in the period directly before their death, but were in a healthy condition. The results of a number of detailed necropsies being carried out on the stranded animals are yet to be released and could be crucial in determining the cause of the stranding and deaths.

Military sonar has been linked to whale strandings in other parts of the world.  Impacts may include disorientation and flight from the noise source leading to strandings, as well as decompression sickness similar to “the bends” in humans.

Current measures taken by the military to mitigate the harmful effects of sonar concentrate on preventing the loss of hearing in whales and dolphins.  However, WDCS argues these measures do not go far enough.

Sarah Dolman continued, “All whales and dolphins are vulnerable to the possible impacts of intense noise pollution. If we hope for these animals to survive for any time into the future we need to manage all threats, including naval sonar.”

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