SCIENTISTS have set sail to investigate the impact that one of Europe’s biggest war games has on whales and dolphins.

The Hebridean Whale and Dolphin Trust (HWDT) research vessel Silurian will track the Joint Warrior exercise off the west coast of Scotland using hydrophones and other equipment.

It is the second of the military exercises which are held each year in and around The Minch – and comes with continued concern over the threat to whales and dolphins.

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More than 5,000 military personnel from armed forces around the world are involved in the war games, alongside 31 ships and submarines, as well as 67 aircraft.

Military sonar used during the exercise emits intense noise that can disturb whales and dolphins, which rely on sound for navigation, foraging and communication.

Naval sonar, more commonly linked to mass stranding events of deep diving whales, has also been associated with minke whale strandings in the Bahamas and in North Carolina.

Lauren Hartny-Mills, HWDT science officer, said: “During previous surveys which have coincided with the Joint Warrior exercises, HWDT has observed minke whales moving at high speed and leaping clear of the water, at the same time as military sonar was detected on the hydrophone.

“This behaviour is unusual here and is rarely seen in undisturbed whales. The long term impact of such disturbances or exposure to sonar are largely unknown.”

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During the exercise, which runs until Thursday, HWDT is asking people to report any sightings of marine mammals in the area.

A pod of pilot whales were stranded at the Kyle of Durness in July 2011, in what is believed to have been Scotland’s largest ever such event.

Four large bombs exploded underwater by the Royal Navy were later blamed for the mass stranding.

A report by the Department for Environment, Food and Rural Affairs concluded that the explosions could have damaged the navigational abilities of the whales, causing them to beach and die.