A “mystery” pod of killer whales spotted off the coast of Scotland three years ago was rediscovered off the west coast of Norway.

Photographs of the killer whales in Børøyfjorden were brought to the Norwegian Orca Survey by citizen scientist Asmund Aasheim.

Six orcas were photographed on Norway’s west coast earlier this year (2021) but had a colouration on their backs unlike other animals in the area.

After consulting Scottish records, the Norwegian Orca Survey matched three of them to a Vatersay sighting by the Herbridean Whale and Dolphin Trust in 2018.

In response to the discovery, experts said a three-year “enigma” had been solved.

Photographs of the killer whales in Børøyfjorden were submitted to the Norwegian Orca Survey by citizen scientist Asmund Aasheim. Where Founder of the group, Dr Eve Jourdain, realised that the pod was not familiar from Norwegian records. The back colouration—known as a saddle patch—pointed her to records further afield.

The images revealed a match identified through distinctive coloration on the back of the whales (area known as the saddle patch).

On 10 July she found a match in the Scottish Killer Whale Catalogue—a key research document containing the best available images of all known living orcas seen in Scottish waters.

“It was incredible to find this first photographic match between Norway and Scotland,” remarked Jourdain.

Researchers at the Hebridean Whale and Dolphin Trust and the authors of the Scottish Killer Whale Catalogue subsequently confirmed that three of the killer whales in the Norwegian encounter were specific individuals known from the Scottish Catalogue.

The trust’s science officer Becky Dudley captured pictures of the whales in 2018 which made the Norwegian match possible.

“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,” she said.

Dr Lauren Hartny-Mills, the trust’s science and conservation manager, said the new sighting highlights the importance of citizen science to the monitoring of wide-ranging animals such as whales and dolphins.

In her words,”We still have so much to learn about whale movements, and it’s fascinating to be able to add another important piece to the puzzle. Through working with citizen scientists and by collaborating with colleagues from Scotland, Norway and beyond, we really hope to learn more about this group.”

Photo-identification is a widely used, non-intrusive research method which allows researchers to identify individual whales from natural markings or features on their bodies. Such images are catalogued and over time build an important long-term picture about whale movements—helping scientists to assess the movements and health of specific individuals. These insights are vital for informing suitable conservation measures.

The method was first introduced by late Dr Michael Bigg in the eastern North Pacific and has been used by scientists worldwide ever since. In Norway, photo-identification studies were initiated in 1984 and were carried out by colleagues until 2005. Norwegian Orca Survey took over the ID-project in 2013, ensuring the legacy of this work. The merging of historical and current ID-catalogues is underway, with the ultimate goal of building the longest dataset on Norwegian killer whales, from 1984 to present.  

The recently published Scottish Killer Whale Photo-Identification Catalogue 2021 has been compiled by five dedicated naturalists—Andrew Scullion (Orca Survey Scotland), Hugh Harrop (Shetland Wildlife), Karen Munro, Steve Truluck (Steve Truluck At Sea) and Dr Andy Foote (Norwegian University of Science and Technology). The authors are absolutely delighted that the Scotland-Norway match was made using the catalogue.

With marine mammals at risk from human activities including climate change, entanglement, pollution, underwater noise and habitat degradation, ongoing and long-term research is crucial to improve understanding of the impacts on whales, dolphins and porpoises—collectively known as cetaceans—and how to protect them. 

Anyone can get involved to help track the movements of individual animals and contribute to marine conservation efforts by sending in sightings and photographs of whales, dolphins, porpoises and basking sharks. For Norway report to Norwegian Orca Survey and for the west coast of Scotland to the Hebridean Whale and Dolphin Trust.

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