A record number of dolphins have been spotted off the west coast of Scotland.

Conservation charity Hebridean Whale and Dolphin Trust (HWDT) said a total of 2449 dolphins were catalogued during expeditions in 2016.

This figure included 2303 common dolphins, 42 bottlenose dolphins and 94 Risso's dolphins.

Dr Lauren Hartny-Mills, HWDT science officer, 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 ongoing monitoring and research to strengthen our understanding of what is taking place in Hebridean waters and to ensure well-informed conservation action."

HWDT has recorded just 463 common dolphins on average each year in the previous 14 years, along with 14 bottlenose dolphins and 12 Risso's dolphins.

Seventy-one volunteers worked with marine scientists during the latest survey which was carried out between May and October last year.

HWDT 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.

"Long-term scientific studies of this globally-important habitat and its inhabitants are crucial if we are to ensure a secure future for the Hebrides' spectacular cetaceans."