Résumé
The objective of this project was to obtain scientific advice for the purpose of implementing the EUPOA on sharks as regards the facilitation of monitoring fisheries and shark stock assessment on a species-specific level in the high seas. The study was focused on major elasmobranch species caught by both artisanal and industrial large pelagic fisheries on the High Seas of the Atlantic, Indian and Pacific area, which are currently monitored and potentially managed by respective Tuna RFMOs. Estimated “potential” shark species catch in the Indian Ocean is around 160,000 t for 22,000 t. presently declared (7 times higher than declared). Considering all sharks that are not reported at species level, the total amount of shark declared was around 100,000 tons and, thus, the underreporting reduced to 1.6 times higher. 19 fisheries among the 195 fisheries found in IOTC database generate 86 % of potential investigated shark catches. In the Indian Ocean, Gillnet (GN) and a composition of Gillnet and Longline (GN-LL) are the most impacting one with 61 % of the total estimated studied shark species catches (97,000 t). It is followed by longline (LL and LL-swo) with 18 % and other métiers (OTH) with 12 %, which precise gear composition is unknown. The blue shark is estimated to be the major shark catch in the Indian Ocean followed by silky shark, threshers, Oceanic whitetip, shortfin mako and hammerheads sharks. The research framework to be proposed is organized in three steps: (i) estimation of shark catches by species using the method proposed here which allows identifying the most impacted shark species and the métier most affecting those species; (ii) a preliminary Ecological Risk Assessment (or other preliminary assessment based on fishery indicators) by fleets which allows to identify the most vulnerable species to focus the efforts in conjunction with point (i); and (iii) specific recommendations of how to apply possible management measures, to improve data collection and assessment of those fleets/species identified as priorities based on points (ii) and (iii). The implementation of the three steps is highly related.