Explosion in dolphin population off west coast baffles experts
SCIENTISTS are baffled as to why dolphins are prospering in the seas off Scotland’s west coast with record numbers of three previously rare species.
Volunteers and professional experts sighted 2,303 individual common dolphins, 42 bottlenose dolphins and 94 Risso’s dolphins last year from a specially-equipped yacht.
The figures for all three species were the highest ever recorded in its annual survey seasons and compared with an average for each of the previous 14 years of 463 individual common dolphins, 14 bottlenose dolphins and 12 Risso’s dolphins.
In two earlier surveys, no common dolphins were spotted. The Hebridean Whale and Dolphin Trust, which produced the studies, is calling for more volunteers to come on board the vessel, the Silurian. The “citizen scientists” would work for stints of almost two weeks from April to September.
Dr Lauren Hartny-Mills, the conservation charity’s 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 on-going monitoring and research, to strengthen our understanding of what is taking place in Hebridean waters, and to ensure wellinformed conservation action.” It is all part of the trust’s unique long-term “citizen science project” monitoring whales, dolphins and porpoises, collectively known as cetaceans, as well as basking sharks in the Hebrides.
There were 71 paying volunteers on Silurian in 2016. They worked with marine scientists on visual surveys and acoustic monitoring with underwater microphones or hydrophones; and identifying individual cetaceans through photography. The Tobermory-based trust holds data from more than 59,000 miles of survey efforts and aims to pass 62,000 this year. Director Alison Lomax said: “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.”