The Basking Shark (An Liamhán Gréine - "Sun or Sail Fish", Cetorhinus maximus) is the largest fish in the Northern Atlantic and the second largest in the world. It is characterised by its large dorsal fin and docile surface swimming behaviour. There is limited biological knowledge available regarding this mega-fauna species and substantially less behavioural knowledge has been published. The majority of historical records are from basking shark fisheries established for the profitable commerce of its valuable liver oil and fins.
The basking shark was until recent years a target fishery of International importance in the North-east Atlantic, particularly for Norwegian, Scottish and Irish based fisheries. Characterised by a well-recorded localised boom and bust fishery cycle its current population trend is unknown. In recent year’s conservation led studies have provided data and supported theories on the behavioural patterns of the species. Numerous methods have been used to estimate local basking shark populations but none stand up to robust scrutiny. The reason for this failure is the use of assumed data and un-established patterns to form key pillars within the survey results.
Today based on the precautionary principle the Basking shark is listed by the ICUN as endangered in the North-east Atlantic.