Scientists seeking to discover whether the seas around the Hebrides seas are a mating ground for basking sharks have gathered new footage showing the sharks being sociable, including a first look at groups forming on the seabed.
Data has been gathered by Scottish Natural Heritage (SNH) and the University of Exeter as part of a new camera tagging project.
Basking sharks are the second largest fish in the world, reaching lengths up to 10m.
Despite their size and prevalence in Scotland’s seas, little is understood about their social behaviours.
Dr Suzanne Henderson, policy officer at SNH, said: “A large number of sharks appear each year just off the western coast of Scotland in the Sea of the Hebrides.
“However, there’s been limited research to show exactly what they’re doing here: do they come solely to feed on plankton, or are they courting each other and using our coast as a mating ground?”
Researchers from SNH and the University of Exeter have attached camera tags to three basking sharks. The video footage collected by the tags will give scientists a new understanding of basking shark group behaviour.
Dr Henderson continued, “There’s 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.
Dr Matthew Witt of Exeter University said: “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. 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.”
A satellite tagging project two years ago showed for the first time that individual sharks return to the same areas off Scotland’s coasts each summer.
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