Marine biologists probe mystery illness after spike in whales washed up on French beaches

Creatures do not appear to have been hit by ship or caught in trawler's net

Experts at the Observatoire Pelagis examine the dead body of a fin whale which was found stranded on a beach in Saint-Hilaire-de-Riez (REUTERS)

Marine biologists fear a mystery viral disease could be to blame after at least six malnourished whales were found washed up along the western coastline of France.

Researchers used a mechanical digger and long knives to dissect a fin whale, the second largest species of whale after the blue whale, after a spike in deaths.

None of the creatures appears to have been hit by a ship or caught in a trawler's net, leading investigators to suspect a viral pathogen may be causing the deaths.

Willy Dabin, a researcher from the Pelagis Observatory, who was working on one corpse, said: ”We have what is almost an epidemic or, at any rate, an abnormal spike in deaths”.

The most recent fin whale corpse was found on Friday near Saint-Hilaire-de-Riez. It measured nearly 16 metres and weighed an estimated 10 tonnes.

The common fin whales have all died within the past six weeks. All have been malnourished and shown evidence of haemorrhaging in the cardiac and respiratory systems.

A seventh, non-native whale was also found washed up, but researchers said they believed that animal had died of natural causes.

"The question lurking in the background is: are humans a contributing factor in their capacity to upset the environment?" Mr Dabin said. "Either by impacting food availability or polluting the living environment, which could leave the whales more vulnerable to disease."

Officials put guards near the carcass at the weekend to keep intrigued locals at a distance.

Laurent Boudelier, a former mayor of Saint-Hilaire-de-Riez, shared photos of the latest dead whale on Facebook, writing that specialists had been sent to the area and urging the public to “absolutely not go near” the area.

Whale carcasses have been known to burst due to a buildup of gas during the decomposition process.

"It's disgusting," said one local man. "I don't know how they're going to remove it. Cut it up piece by piece?"