Spatio-temporal interactions between whale sharks, cetaceans and the European tropical tuna purse seine fishery in the Atlantic and Indian Oceans

The results presented in this newsletter are extracted from my PhD, which was completed at the French Institut de Recherche pour le Développement in Sète, France between 2013 and 2016.2 The aims were to investigate the spatio-temporal interactions (fishing nets set in the vicinity of these species and potentially lead to encirclement) and/or co-occurrences (presence in the purse seine fishing grounds) between whale sharks, cetaceans and the tuna purse seine fishery in the eastern Atlantic and western Indian Oceans, and to assess the potential impacts on the species that are involved. To address these objectives, I have mainly used fishery data from European fleets (France and Spain): i) logbook records systematically filled out by vessel captains since 1980; and, ii) data from scientific observers onboard fishing vessels since 1995 (continuous data collection programmes since 2003). Observers tend to record more detailed and complementary information than captains. However, the number of purse seiners that carried an observer onboard was historically low (<10%), but has increased to 100% in the Atlantic Ocean and ~40% in the Indian Ocean since 2014.