Underwater footage has revealed the secret social lives of basking sharks in Scottish waters for the first time.
Researchers from Scottish Natural Heritage (SNH) and Exeter University were investigating whether the sharks mate off Scotland’s coast.
Despite their size and prevalence in Scotland’s seas, little is understood about their social behaviours leading the researchers to spend a week off the coast of Tobermory.
There, in a world first, they tagged three basking sharks using towed camera tags that trail slightly behind the point of attachment on the main dorsal fin.
It is believed to be the first time this type of tag has been used on basking sharks and the resulting video footage will give scientists a new understanding of their group behaviour.
The footage they gathered of the sharks – the second largest fish in the world, growing to around 33 feet long – gives a first glimpse of them congregating in groups on the seabed.
Additionally, the data collected will inform future consultations on a Marine Protected Area by identifying why the area is important to the sharks.
Dr Suzanne Henderson, policy and advice officer at SNH said: “There is very little information about social and mating behaviours in basking sharks, or indeed sharks in general.
“We’ve been unsure whether the surface behaviours we see in the Sea of the Hebrides – such as parallel swimming, following nose to tail, or swimming in tight circles – are courtship activities.”
She added: “The footage we’ve collected gives a fantastic shark’s eye view of the environment and new insight into behaviours.
“We can see sharks very closely aggregating near the seabed, potentially forming social groups.”
Dr Matthew Witt, senior lecturer in natural environment at Exeter University said: “Three sharks are seen very close together, fins touching but hardly swimming.
“We haven’t seen basking sharks exhibit this behaviour at depth, and early in the morning, before.”
Minister for Rural Affairs and the Natural Environment, Mairi Gougeon, said: “The study being undertaken by Scottish Natural Heritage and Exeter University is an exciting opportunity to build our knowledge of how basking sharks use our seas.
“In addition to being a world first for the use of these towed camera tags on this species, this work will enhance the evidence base for a basking shark Marine Protected Area proposal which will be consulted on later this year.”
