skip to main content

Basking shark tagging project

The final results of the basking shark tagging project have just been published in our final report. This exciting joint project between Scottish Natural Heritage and theUniversity of Exeter external site has, over the course of three years, deployed a total of 61 satellite tags. Using some of the newest tracking technology available, this project has been able to provide answers to the questions we posed:

  • How long do basking sharks remain feeding in certain areas in Scottish waters?
  • How are the sharks using these areas which are important to them for feeding and potentially breeding?
  • Where do basking sharks go after their summer feeding in Scotland's seas?
  • Do the sharks remain in deeper waters off Scotland over winter?

Key Findings

  • Tagged sharks demonstrated high levels of fidelity to waters around Coll, Tiree, Hyskeir in the Sea of the Hebrides during summer months (July to September).
  • The first evidence is presented to show that individual sharks returned to the same areas in consecutive summers, after migrating south in winter.
  • During summer months sharks displayed a variety of vertical depth use; diel vertical migration (DVM), reverse DVM and yo-yo diving behaviour - presumably adapting to local environmental conditions.
  • Sharks spent a greater proportion of their time near the surface of water during the daytime compared to nigh-time during summer months, and occupy depths of between 25 and 50m most frequently overall.
  • 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.
  • Many sharks migrated south to the Bay of Biscay, Portugal and three travelled as far as Madeira and the Canary Islands.
  • Some sharks undertook deep diving events in March and April - down to depths of over 1000m.

The University of Exeter is continuing further analysis on our results and these will be published in peer review journals in due course.

Special thanks must go to Colin Speedie, Louise Johnson, Jackie and Graham Hall, James Fairbairns and Iain Malcolm who have all contributed to the project's success. Recognition must also go to colleagues and members of the public who have located and returned an unprecedented number of detached tags that washed ashore, thereby adding to the wealth of data collected.

How can you help? Return any tags you find!

You can still help the project by returning any detached tags you come across washed-up onto the beach. The tags have provided us with a lot of information from satellite transmissions but if we can retrieve them after they fall off we can learn even more. If you return a tag you can also claim a reward  PDF document !

Please keep an eye open when you are on the shore for tags (see photo). If you do find a tag, please contact the Scottish Natural Heritage Oban Office on 0300 244 9360, or email -

Last updated on Thursday 21st January 2016 at 10:56 AM. Click here to comment on this page