A POD of pilot whales that stranded on the Fife coast last week may have been led to their deaths by a sick elderly female, the initial findings of their post mortem examinations has revealed.

The female is thought to have been a matriarchal figure in the pod of five animals first spotted struggling in shallow water near Culross last Tuesday.

At the time, the largest male – a two-ton adult –seemed to be trying to keep one of the females afloat.

The following day, three of the whales live stranded at nearly Torryburn and on Thursday the female was one of two that washed up dead nearby and at North Queensferry, while two males had to be put down on vets’ advice.

Tests have now shown that the adult female – which measured 4.56m and weighed almost one ton – had bacterial infections and abscesses throughout its body that may have been present for months and caused her death.

The other whales are thought to have been trying to help their matriarch when they too became stranded in mud and consequently suffered fatal internal injuries.

The fifth member of the pod has not been seen and it is hoped it was able to return safely to the sea.

Dr Andrew Brownlow, veterinary pathologist for the Scottish Marine Animal Stranding Scheme (SMASS), who carried out the post mortem examinations, said: “Pilot whales have a very matriarchal structure – they tend to follow a lead female in the pod – and it is possible that one of these lead females was poorly and got into trouble.

“Because she wasn’t behaving normally, as she was so sick, she’s ended up stranding on the mudflats in North Fife. In that process of stranding, the other animals came to help and they too got in to trouble as they all went in to the shallow water.”

“When you are an animal that weighs over two tons -- as one of the males did -- when you are left high and dry and the water has receded, that brings about a cascade of pathological processes that will kill the animal no matter how healthy it was.

“The process of stranding for an animal that size is invariably fatal and the two males stranded possibly three times. As a result the only thing we could do for them was to euthanise them. So much damage had been done to them that there was no way they would survive.”

The whales’ native habitat is around 100 miles off the west coast of Scotland, on the edge of the continental shelf, where the deep diving animals feed on squid.

It is thought the matriarchal female, due to sickness, may have become unable to navigate, become lost or sought shelter and the others followed.

Further test results could take several weeks., examinations of the carcasses suggested the worst affected female had produced up to five calves in her life and may have been over 30 years old when she died.

None of the animals had eaten for several days. However, there was no evidence of acoustic trauma, that noise played a part; no evidence of entanglement, toxicity or trauma from boats; and none of the whales had ingested any plastics.

Dr Brownlow said: “They all showed signs of pathology but what until I’ve got the results from the tests I’m running at the moment what I can’t be clear on is whether or not that pathology was preexisting or whether it was caused by the stranding process.

“The one I’m absolutely certain of is this female, which was very poorly. She had enough bacterial infections and abscesses through her body that had been there for weeks, months and possibly even years in some cases, and she had just run out of energy.

“This animal had enough bacterial disease to account for the reason why it was stranding, and from what we saw from the behaviour of the others, they seemed to be trying to help it and they did not seem to be exhibiting much pathology.
“You put all of that together and what you get is a sick animal and others trying to help it.”

Dr Brownlow said the attempted rescue and the retrieval of the whale carcasses for post mortems had been “an astonishingly difficult logistical and emotionally draining process”. He also praised the work of the British Divers Marine Life Rescue (BDMLR), who spent three days trying to save the mammals.

He added: “Humans can have profound and wide ranging impacts on cetacean populations but, by having the ability to do these post mortems, in this case we can say that it just seems to be animals that were poorly.

“These are not dumb animals -- the brain of the smallest pilot whale that I saw was two and a half times the size of a human brain, and that’s higher brain function, the cortex, to do with language, communication, social bonds. They are clever, highly complex, social animals.