Interactions of Oceanic Whitetip Sharks with the Tuna Purse Seine Fishery in the Indian Ocean

The interaction between oceanic whitetip sharks (OCS) and the purse seine fishery in the western Indian Ocean was analyzed, in order to investigate the potential of using this fishery’s database to derive abundance indexes and determine population trends for the species.
Observer data from the French purse seine fleet combined with a historic database from the Soviet Union were used in the analyses. The combined time series spanned from 1986 to 2014. A well-¬‐marked change on the proportion of Fishing Aggregating Devices (FADs) with the presence of oceanic whitetip sharks was observed, fluctuating around 20% from mid 80’s to mid 90’s and dropping to less than 10% as from 2005. The changes on the OCS/FAD proportion along the years show a clear link between the two distinct databases. The results indicate that the proportion of FADs with OCS could be relevant when deriving abundance trends for the species form multiple data sources.