Record numbers of dolphins have been spotted off Scotland’s west coast during the latest ocean research surveys.
Sightings of three dolphin species in waters around the Hebrides in 2016 were the highest recorded in the past 14 years. Volunteers and scientists recorded 2,303 individual common dolphins, 42 bottlenose dolphins and 94 Risso’s dolphins last year.
In studies going back to 2002, an average of 463 common dolphins, 14 bottlenose dolphins and 12 Risso’s dolphins were seen during annual counts.
Sightings of common dolphins have shown particularly dramatic changes over the years. None were encountered in some of the early seasons, compared to 1,862 in 2007.
With a long, complex coastline, strong ocean currents and a diverse range of marine features, the seas around western Scotland are among the UK’s most biologically productive areas.
They provide some of Europe’s most important habitats for dolphins and whales, known as cetaceans
To date 24 of the 92 cetacean species known to exist globally have been recorded in the region – many of them listed internationally as priorities for conservation.
Marine scientists have welcomed the results but say they are unsure what is driving the increase in dolphins.
It is thought that ongoing rises in sea temperature, as a result of climate change, could be a major factor.
Dr Lauren Hartny-Mills, science officer at the Hebridean Whale and Dolphin Trust, said: “The reasons for the high number of sightings of these charismatic dolphin species, and the broader effects on the marine environment and other species, remain unclear.
“But the intriguing findings highlight the importance of on-going monitoring and research – to strengthen our understanding of what is taking place in Hebridean waters and to ensure well-informed conservation action.”
Charity director Alison Lomax added: “The impressive range of species documented in our at-sea surveys last year is a powerful reminder that Scotland’s west coast ocean environment is home to remarkable marine life.”
Despite their name, common dolphins were only occasionally seen in the Hebrides in days gone by – preferring warmer waters to the south.
Climate change is causing the sea surface in the Hebrides to rise by 0.5C per decade.