Sightings of young minke whales and dolphins off the west coast of Scotland have grown to their highest-ever recorded level this year.

More than 720 dolphins were spotted at 63 locations - more than double from when records began 12 years ago - during marine research expeditions carried out by Hebridean Whale and Dolphin Trust.

There was also a three-fold increase in the number of young minke whales seen with 28 juvenile whales and 30 adults spotted during the survey between March and October this year.

Experts said it was an unusually high proportion of young compared to adults, with an encounter rate of one juvenile minke per 286km (177 miles) travelled by the Silurian, the trust's dedicated research yacht.

Officials described the increase as "encouraging" but said serious conservation issues remain around minke whales, with the species hunted in waters around Iceland and Norway.

The Silurian, used in filming of the BBC's Blue Planet series, covered more than 4,000 nautical miles as part of the survey between March and October, with the crew of volunteers and scientists documenting more than 1,200 encounters with cetaceans and basking sharks, and recording almost 625 hours of underwater detections of cetaceans using specialist listening equipment.

The trust said the annual surveys depend on volunteers, with a group of 69 working 760 hours with marine scientists to conduct visual surveys, monitor underwater microphones and identify individual cetaceans through photography of dorsal fins.

Kerry Froud, Hebridean Whale and Dolphin Trust biodiversity officer, said: "These intriguing changes in Scotland's marine life highlight the importance of long-term monitoring of cetaceans - so that we can better understand what is happening in our waters, and then make management recommendations to better protect this world-class area of marine biodiversity."

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