A killer whale died after being caught in fishing gear, it is believed.
The body of the female orca -
She was one of a small pod which are resident in the Minch.
It is thought only eight whales now remain in the group.
No fishing gear was found on the body but vets at the Scottish Marine Animal Strandings Scheme carried out a post mortem.
They reported: "We found convincing evidence that she had become chronically entangled and this was the most likely cause of her death.
"There were deep, granulating wounds around the tailstock and tell-
"These are consistent with a rope wrapping around the tail and trailing behind the animal, probably still attached to something at the other end. This would have made normal swimming very difficult, and we suspect the animal had been entangled for several days.
"She hadn’t fed recently but had swallowed a large amount of seawater, most likely as she eventually succumbed to the entanglement and drowned."
No ropes or fishing equipment was found on the carcase. Scientists made their assumptions from the lesions on her body.
They said: "We don’t know if this was due to active fishing gear, abandoned or ‘ghost’ gear, or other marine debris. The lesions are very similar however to those we see from creel rope entanglement in baleen whales.
"This is the first killer whale we have seen which has been entangled, although we have had an increase in entanglement incidence in other large cetaceans over the past year."
The Hebridean Whale and Dolphin Trust fears their survival as a community is at grave risk.
The charity believes that the group is likely to become extinct, as no calves have been spotted with them since research began 20 years ago.
Killer whale died after fishing gear entanglement
10 January 2016