Britain’s basking sharks
Basking sharks were heavily fished in the past. Now these gentle and elusive giants are protected in Europe, but we still have a lot to learn about them. Using a collaborative photo-ID database, Cat wants to understand their life history and movements.
Cat Gordon
My keen interest in nature and the environment developed when I was young, although living in central England, well away from the coast, meant that my curiosity about the underwater world took longer to emerge. It was learning to scuba-dive at the age of 14 that led me to fall in love with the ocean and appreciate its inhabitants. Faced with choosing a career, I jumped at the opportunity to study for a BSc in marine biology and coastal ecology and then an MSc in conservation biology with a view to working in the marine conservation sector. I had a...
Basking shark community project
The key aim of this project is to build a comprehensive photographic database of basking sharks observed in the UK, while simultaneously using satellite tracking to observe and investigate their migratory movements into international waters.
At up to 10 to 11 metres in length and five to seven tonnes in weight, the basking shark Cetorhinus maximus is the second largest fish in world. However, as a result of fishing pressure, its global existence is now seriously threatened, with the species’ total population thought to have diminished to around only 8,200 individuals.
The basking shark, the world’s second largest shark, is a planktivore – like the whale shark – but confined to temperate waters. It has long been exploited in the Atlantic for its liver oil, and more recently, it has largely disappeared from the Pacific as a result of the Asian demand for shark fin. The work led by Dr Mauvis Gore for the SOSF-funded project has both provided additional insights into this charismatic species and collected data suggesting that following protection in the UK, numbers may be recovering.
The 2009 Basking Shark Conference, which the SOSF sponsored, concluded that the best way to basking shark monitor numbers would be to implement a photo-identification scheme that can generate population estimates through mark-recapture modelling. Consequently in April 2010 a community photo-ID project was launched involving four separate research teams – in Scotland, the Isle of Man, England and Ireland – and a joint database established at the Shark Trust in Plymouth.
Currently work is underway to catalogue the sharks sighted and check for matches with those individuals photographed in previous years. In addition, teams have been collecting tissue samples from which an independent assessment of population structure and size can be derived.
The aims of the project are:
- Derive reliable estimates of population levels and trends for basking sharks in north-west Europe through boat-based surveys, photography for identification and collection of tissue samples for DNA analyses.
- Promote public awareness of basking sharks as a means of securing their protection and conservation through an environment exhibition at Breachacha Castle (Isle of Coll).