Basking shark | European Tracking Network

Basking shark

Cetorhinus maximus

Species description and status: The basking shark is the second largest fish in the world, reaching 12.27 m in length (Carwardine, 1995), with a broad distribution in temperate waters (e.g. Francis & Duffy, 2002; Natanson et al., 2008; Witt et al., 2012). The species is wide ranging with individuals noted diving to >1 km deep (Sims et al., 2003; Gore et al., 2008; Ebert et al., 2013) and undertaking trans-Atlantic movements (Gore et al., 2008; Johnston et al., 2019). However, due to historical fisheries pressure and persecution, the species is now listed as Endangered by the IUCN (Rigby et al., 2020) and further research is highly recommended to understand population connectivity and aid protective measures.

Knowledge gaps: While there has been a significant effort in recent years to better understand basking shark spatial movements using telemetry studies (e.g. Doherty et al., 2017, 2019; Dolton et al., 2019), further information on their long-term distribution over broader scales is required for effective European-wide conservation management plans. Overall, more detailed information into population abundance and connectivity would be highly valuable for management teams. As basking sharks are known to travel long distances, protective measures are required to cover international jurisdictions in order to be effective. Satellite tagging studies have provided incredible insight into individual movements for 9-12 month periods (satellite tag battery time limits), and this provides an excellent basis for longer-term studies using acoustic tags (battery life of up to 10 years) to assess inter-annual movement patterns and population connectivity over a broader scale.

Regions of interest: The North Atlantic Ocean, and Mediterranean Sea

Telemetry tools: Satellite tracking has been used extensively on this species to great affect and now longer-term data storage tags and acoustic transmitters offer the ability to collect inter-annual movement data. This would be particularly valuable to assess shark movement patterns in coastal waters where interactions with boat traffic and fisheries gear is more likely. Such work would be further complimented by continued use of satellite archival tags to assess fine scale movement patterns and assess spatial use.

Benefits: Using the ETN to provide new insight into basking shark movements and long-term spatial use patterns would significantly increase our ability to build conservation management plans for this endangered species. As basking sharks are known to be wide ranging and able to cross multiple EEZs, the ability to combine research efforts and share data is hugely valuable to help assist population recovery and long-term protection.

Contacts: Natasha Phillips (nphillips01@qub.ac.uk)

References

Carwardine, M. (1995) The Guinness book of animal records. Guinness Publishing, Middlesex, UK.

Doherty, P.D., Baxter, J.M., Gell, F.R., Godley, B.J., Graham, R.T., Hall, G., & Hall, J. (2017) Long-term satellite tracking reveals variable seasonal migration strategies of basking sharks in the north-east Atlantic. Scientific reports, 7, 1–10.

Doherty, P.D., Godley, J.M.B.B.J., Hall, R.T.G.G., & Hawkes, J.H.L.A. (2019) Seasonal changes in basking shark vertical space use in the north ‑ east Atlantic. Marine Biology, 1–12.

Dolton, H.R., Gell, F.R., Hall, J., Hall, G., Hawkes, L.A., & Witt, M.J. (2019) Assessing the importance of Isle of Man waters for the basking shark Cetorhinus maximus. Endangere, 41, 209–223.

Ebert, D., Fowler, S., & Compagno, L. (2013) Sharks ofthe world: a fully illustrated guide. Wild Nature Press, Plymouth, UK.

Francis, M. & Duffy, C. (2002) Distribution, seasonal abundance and bycatch of basking sharks (Cetorhinus maximus) in New Zealand , with observations on their winter habitat. Marine Biology, 140, 831–842.

Gore, M.A., Rowat, D., Hall, J., Gell, F.R., & Ormond, R.F. (2008) Transatlantic migration and deep mid-ocean diving by basking shark. Biology Letters, 4, 395–398.

Johnston, E.M., Mayo, P.A., Mensink, P.J., Savetsky, E., & Houghton, J.D.R. (2019) Serendipitous re-sighting of a basking shark Cetorhinus maximus reveals inter-annual connectivity between American and European coastal hotspots. Journal of Fish Biology, 95, 1530–1534.

Natanson, L.J., Wintner, S.P., Johansson, F., Piercy, A., Campbell, P., Maddalena, A. De, Gulak, S.J.B., Human, B., Fulgosi, F.C., Ebert, D.A., Hemida, F., Mollen, F.H., Vanni, S., Burgess, G.H., & Compagno, L.J. V (2008) Ontogenetic vertebral growth patterns in the basking shark Cetorhinus maximus. Marine Ecology Progess Series, 361, 267–278.

Rigby, C. et al (2020) Cetorhinus maximus, Basking Shark IUCN listing. 8235, .

Sims, D.W., Southall, E.J., Richardson, A.J., Reid, P.C., & Metcalfe, J.D. (2003) Seasonal movements and behaviour of basking sharks from archival tagging: no evidence of winter hibernation. Marine Ecology progess Series, 248, 187–196.

Witt, M.J., Hardy, T., Johnson, L., McClellan, C.M., Pikesley, S.K., Ranger, S., Richardson, P.B., Solandt, J.L., Speedie, C., Williams, R., & Godley, B.J. (2012) Basking sharks in the northeast Atlantic: Spatio-temporal trends from sightings in UK waters. Marine Ecology Progress Series, 459, 121–134.