A "mystery" pod of killer whales last seen in Scotland three years ago have been spotted again off the coast of Norway.
The last known sighting of the six orcas was previously off Vatersay in the Western Isles in June 2018.
Now after three years of going under the radar, three of them have been spotted again on Norway's west coast.
The reason they stand out from the rest of the killer whales is due to a colouration on their backs.
Experts have said that a three-year "enigma" has now been solved, with three of the killer whales matched to the ones on the Scottish record.
The breakthrough came on July 10, after citizen scientist Asmund Aasheim photographed a pod of six orcas in Børøyfjorden and sent his pictures to the Norwegian Orca Survey, where Dr Eve Jourdain found that the killer whales were not familiar from Norwegian records.
The back colouration - known as a saddle patch- looked different to that of killer whales normally seen around Norway.
She found a match instead in the Scottish Killer Whale catalogue.
Dr Jourdain said: “From the moment I first took a look at Asmud’s photos, I knew these killer whales were “different” from our Norwegian killer whales.
"Following our routine protocols, I tried to identify them from our Norwegian Catalogue anyway, but as expected, I found no match.
"When it came to mind that I should browse through the Scottish Catalogue, I had a strong feeling that I would find them there. And, bingo!
"It was incredible to find this first photographic match between Norway and Scotland!"
The only previous confirmed sighting of this killer whale pod had been made by the Hebridean Whale and Dolphin Trust (HWDT) on 23 June 2018.
Photo identification and citizen science is widely used to track and identify marine life and is said to be the best way to inform conservation measures.
It is when members of the public send in pictures of marine life to groups such as the HWDT so they can add them to their large database.
HWDT's science officer Becky Dudley captured the photos of this pod of killer whales that made the Norwegian match possible.
She said: “The encounter with this group of killer whales back in 2018 was one of the most amazing experiences I’ve had on Scotland’s west coast.
"It was made even more exciting when – despite much investigation and collaboration with other organisations – the identity of this pod remained a mystery.
"I am thrilled that the group has been matched to the group seen in Norway over three years later. It highlights how much there is to learn about the marine life in our oceans.”
