THEY may be, scientists fear, the biggest victims of the new Cold War ... an “unprecedented” number of whales washed up on Scotland’s shores in 2018.

Experts have long warned

underwater military activity might

cause such deaths.

Such concerns heightened late last summer as a reported upsurge in war games between Nato and Russian submarines in the north-east Atlantic coincided with record beachings of Cuvier’s beaked whales, a deep-diving species.

Now new research has ruled out an alternative theory: that a virus might have killed scores of Atlantic whales

this year.

The finding has strengthened suspicions that submarine sonars were responsible for harming the whales, leading to their deaths.

Marine researchers previously confirmed an unprecedented number of beaked whale fatalities occurring off the west coast of Scotland. And they have described it as the “largest mortality event of this species anywhere, ever”.

British and Nato commanders are understood to be playing cat-and-mouse with their Russian rivals in scenes reminiscent of Cold War movies such as

The Hunt For Red October.

Since August, 66 whales, mostly Cuviers, have washed up in various stages of decomposition on beaches and coastlines from Orkney to Kintyre.

The last animal linked to the event was on November 6 – when a northern bottlenose whale was found at Borve on Lewis – but the vast bulk of the tragic finds were in August and September.

Some of the cetaceans have also been discovered on the west coast of Ireland, and Northern Ireland, bringing the total to moe than 90.

The Scottish Marine Animal Stranding Scheme (SMASS) said the wave of fatalities is a mystery.

The vast majority of the washed-up whales have been too decayed for necropsies to positively identify how

or why they died.

But Nick Davison, strandings coordinator at SMASS, said that tissue tests on 26 animals had revealed they had not died from a virus – ruling out such a natural cause.

“We looked particularly for the morbillivirus, which is associated with measles in humans, distemper in dogs and has caused mass mortality in seals previously,” he said.

“But the tests all proved negative. We are also carrying out genetic testing to see if they are from the same group and population that would add weight to

an event happening in one geographic location.

“We are also pushing the MoD for more information. “

Mariel Ten Doeschate, a data analyst with SMASS, has said that sonar signals from submarines or seismic surveys could be among the contributory factors.

It is thought that the sonar waves

can frighten deep-diving whales, forcing them to surface too quickly and leading to symptoms similar to decompression sickness, also known as the bends,

in humans.

In May. Gavin Williamson, the UK Defence Secretary, said that Russian submarine activity in the north Atlantic had increased tenfold.

He said that in 2010 a Royal Navy ship was called on just once to respond to Russian navy vessels, whereas last

year the UK had to react 33 times.

Nato officials have said that Russian submarine activity is at the highest

levels since the Cold War.

Mr Davison also said a number of dead northern bottlenose whales

had also been found on the east

coast of Iceland. It is not known if

this is connected.

He added: “Like Cuviers, they are deep diving and mainly feed on squid. They are badly decomposed and in many cases partial animals – so it is going to be difficult to establish the cause of their deaths.”

As with other beaked whales species, the northern bottlenose whale is believed to be susceptible to the effects of loud man made noise. Cuvier’s beaked whales are also some of the deepest-diving mammals on the planet, and rely on sonar and echo location

to navigate the pitch-black depths

of the Atlantic Ocean, more than

a mile deep.

As a result, they are highly susceptible to loud underwater sounds such as sonar, which some marine biologists worry could be causing them to surface too quickly in distress.

Mr Davidson added: “Our average stranding numbers for these animals is around two and a half per year.

“So the number we’ve had over the past months is pretty much unprecedented – anywhere.”

But a spokesman for the MoD has

said the Navy does all it can to ensure sonar is not damaging marine life.

He added: “There is no evidence that the deaths of these marine mammals have been attributed to any sonar operations, trials or exercises.

“The Royal Navy takes its responsibilities in safeguarding the environment very seriously and, when

at all possible, operators take avoidance actions should animals be detected before or during sonar operations.”

Both UK and Scottish governments have ordered investigations into the whale deaths.

In 2011, 19 pilot whales died after becoming stranded on the north coast

of Scotland. A report concluded that four large bombs detonated underwater by the Royal Navy were to blame.