Record numbers of common dolphins have been spotted off Scotland’s west coast in the past 12 months, according to the latest figures.
Surveys by the conservation charity Hebridean Whale and Dolphin Trust (HWDT) show sightings of common dolphins around the Hebrides rose by nearly a quarter in 2017 compared with the year before.
HWDT scientists and volunteers recorded 93 sightings of the species last year, up from 75 in 2016.
However, the total number of individual common dolphins seen – 1,340 – was considerably lower than the all-time high seen a year earlier.
In 2016, larger group sizes and a greater proportion of “super pods” resulted in a record-breaking 2,303 of the animals being counted.
Experts believe global warming may be behind the increasing presence of the species in Scottish waters.
“We have never documented so many sightings of common dolphins off Scotland’s west coast before,” said Dr Lauren Hartny-Mills, HWDT’s science and policy officer.
“Our findings highlight the importance of ongoing monitoring and research to strengthen our understanding of what is taking place in Hebridean waters.
“It is hard to say what is causing this increase, but a rise in sea surface temperatures linked to climate change could be playing a role.”
The charity has also recorded a higher than average number of sightings of white-beaked dolphins over the past two years, with 74 animals seen in 2017.
The harbour porpoise remained the most commonly seen species last year, with 621 individuals seen. A total of 80 minke whales and 58 Risso’s dolphins were also logged, which is similar to figures from previous years.
In all, more than 3,000 individual whales, dolphins, porpoises and sharks were recorded in a total of 1,100 sightings in 2017.
The latest findings come shortly after Sea Watch Foundation released the results from last year’s annual UK-wide National Whale and Dolphin Watch survey.
Harbour porpoises were also the most commonly seen cetacean species during the national poll, with bottlenose dolphins in second place.
Scottish waters are internationally important for whales, dolphins and porpoises, with more than 20 cetacean species found around the country.
Seven are relatively common close to our coasts: bottlenose dolphin, harbour porpoise, minke whale, white-beaked dolphin, Risso’s dolphin, common dolphin and orca, also known as the killer whale.
The Moray Firth is home to the world’s most northerly resident population of bottlenose dolphins, while the UK’s only resident pod of killer whales lives around the Hebrides.
HWDT has been monitoring marine megafauna in the Hebrides since 1994.
Its work is partly funded by a grant from government nature agency Scottish Natural Heritage (SNH).
Fiona Manson, a marine specialist at SNH, said: “Volunteer citizen scientists make an important contribution to marine conservation in Scotland. The exciting range of marine wildlife in Scottish waters is a huge draw for visitors to our coasts, and is a fantastic way of connecting people with nature.
“Scotland’s network of marine protected areas – including Europe’s second-largest protected area for harbour porpoise, in the Inner Hebrides and the Minch – aims to ensure that these amazing animals remain here for future generations to enjoy.”