Basking shark satellite tagging project - Scottish Natural Heritage

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Scottish Natural Heritage Commissioned Report No. 908

Basking shark satellite tagging project: insights into basking shark (Cetorhinus maximus) movement, distribution and behaviour using satellite telemetry

COMMISSIONED REPORT

Commissioned Report No. 908

Basking shark satellite tagging project: insights into basking shark (Cetorhinus maximus) movement, distribution and behaviour using satellite telemetry Final Report For further information on this report please contact: Dr Suzanne Henderson Scottish Natural Heritage Great Glen House INVERNESS IV3 8NW Telephone: 01463 725238 E-mail: [email protected] This report should be quoted as: Witt, M.J., Doherty, P.D., Godley, B.J. Graham, R.T. Hawkes, L.A. & Henderson, S.M. 2016. Basking shark satellite tagging project: insights into basking shark (Cetorhinus maximus) movement, distribution and behaviour using satellite telemetry. Final Report. Scottish Natural Heritage Commissioned Report No. 908. This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage. This permission will not be withheld unreasonably. The views expressed by the author(s) of this report should not be taken as the views and policies of Scottish Natural Heritage. © Scottish Natural Heritage 2016.

COMMISSIONED REPORT

Summary Basking shark satellite tagging project: insights into basking shark (Cetorhinus maximus) movement, distribution and behaviour using satellite telemetry Final Report Commissioned Report No: 908 Project No: 15078 Contractor: University of Exeter Year of publication: 2016 Keywords Basking shark; satellite tagging; seasonal fidelity; Sea of the Hebrides. Background The areas around Hyskeir, Coll and Tiree have been identified as “hotspots” for basking sharks from 20 years of public sightings record. The area from Skye to Mull, on the west coast of Scotland, has also been recently identified as a Marine Protected Area (MPA) search location as part of the Scottish MPA Project. Large numbers of basking sharks are seasonally sighted foraging and engaging in putative social behaviours, such as breaching and in courtship-like aggregations in this area. These observations highlights that the area may be important for key elements of basking shark life history ecology. To gain detailed insights in to the distribution, habitat-use, movements and behaviours in these areas, Scottish Natural Heritage (SNH) and the University of Exeter (UoE) initiated a research project to attach satellite tags to basking sharks in the summer months of 2012, 2013 and 2014. This report provides analyses, interpretation and comment on data resulting from three years of tag deployments, with particular focus upon basking shark movements and depth use within the Sea of the Hebrides MPA proposal. Main findings 

Satellite tagged basking sharks demonstrated high levels of intra- and inter-annual site fidelity to waters around Coll, Tiree and Hyskeir during summer (July to September).



Basking sharks occupy shallow coastal waters during summer months, predominantly using surface waters, but move to deeper waters from autumn onwards.



The Irish and Celtic Seas represent an important migration corridor for basking sharks moving between the Sea of the Hebrides, the Isle of Man and southwest England.



Tagged basking sharks disperse widely in the autumn, moving to the west of Ireland, the Bay of Biscay, Iberian Peninsula and North Africa. Some sharks however remain relatively close to Scotland throughout the winter.

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Evidence of diel vertical migration (DVM), reverse DVM and yo-yo diving behaviour, suggest basking sharks exhibit a high degree of plasticity when adapting to local conditions.

For further information on this project contact: Dr Suzanne Henderson, Scottish Natural Heritage, Great Glen House, Leachkin Road, Inverness IV3 8NW. Tel: 01463 725