The population abundance and density of basking sharks in any sea area of the world is not known. Monitoring of the UK population of basking sharks has largely been based on sightings of sharks feeding on plankton near the sea surface during spring and summer. Three public sighting recording schemes are presently under way in the UK (The Marine Conservation Society Basking Shark Watch; Seaquest South-West and Solway Shark Watch). The MCS scheme has been running for 20 years and it has observed over 24,000 animals.
Current research (by the Marine Biological Association/Cefas) on basking sharks is using modern satellite telemetry to provide valuable information on movements and behaviour of basking sharks in the north-east Atlantic. Information uncovered to date on the geographical movement of individual sharks suggests that despite making long-distance movements they remain in the vicinity of the continental shelf around the UK, Ireland and northern France. These findings have been consolidated with sightings data from UK charities (MCS, IFAW, Shark Trust, Wildlife Trusts, Hebridean Whale and Dolphin Trust) as part of a three-year Esmee Fairbairn Foundation-funded grant to MBA. The project is bringing together in a single database all recent data on basking shark distribution and this means that it is now possible to undertake comprehensive analyses of trends.
Nevertheless, there is no current reliable population estimate for basking sharks in UK (or European) waters. This is due to the difficulties in relating surface sightings to actual population size. While the broad distribution patterns of basking sharks in UK waters are being uncovered by sightings data, new research using telemetry data suggests there are considerable differences in the density distributions of the animal, with animals 60 times more likely to be at the surface (and thus sighted) in mixed water fronts than stratified water fronts. Genetic research is also under way to determine whether populations of basking sharks are discrete or if there is population mixing between the north-east Atlantic region and elsewhere.
Basking sharks are protected in British territorial waters under Schedule 5 of the Wildlife and Countryside Act 1981. This gives the shark protection out to 12 nautical miles.
It is difficult to designate specific areas for basking sharks given their mobility in UK waters. This would be more appropriate if we are able to identify areas which are key to these animals’ life cycle, such as, important feeding grounds or breeding grounds, or known mating areas that the animals consistently return to. At present, we do not know enough about these animals. A provision is currently being considered as part of the marine Bill to designate marine protected areas. This means that, as our scientific knowledge improves we will be able to adapt our approach to the conservation of this species, which may include the designation of marine protected areas if deemed appropriate.
The Department is in regular contact with the Scottish Executive on a wide range of nature conservation issues, including discussions on basking sharks.