Compilation of information on blue shark (Prionace glauca), silky shark (Carcharhinus falciformis), oceanic whitetip shark (Carcharhinus longimanus), scalloped hammerhead (Sphyrna lewini) and shortfin mako (Isurus oxyrinchus) in the Indian Ocean

At the Ninth Session of the Indian Ocean Tuna Commission in 2005, the commission adopted the resolution 05/05 , arising from the work of the Compliance Committee, concerning the conservation of sharks caught in association with fisheries managed by IOTC. It is stipulated that Contracting Parties and Cooperating non-Contracting Parties (CPCs) shall annually report their data for shark catches, require that their fishermen use their entire catches of shark (fin-body ratio less than 5%), encourage the release of sharks incidentally caught, promote research on sharks; the Commission requires the working party on By-catch (WPBy) to provide preliminary advice on the stock status of key shark species and provide a research plan and timeline for a comprehensive assessment of these stocks. The purpose of this document is to present some basic biological data needed for assessment of characteristics of the following pelagic sharks species under the management mandate of IOTC. Blue shark (Prionace glauca), silky shark (Carcharhinus falciformis), oceanic whitetip shark (Carcharhinus longimanus), Scalloped hammerhead shark (Sphyrna lewini) and Shortfin mako sharks (Isurus oxyrinchus) are , in the Indian Ocean, the species most commonly taken by semiindustrial and artisanal fisheries in many countries and also taken as bycatch, by the pelagic longline fisheries and in a less extent by the purse-seine fishery. This document is based primarily on information from literature and studies carried out in Indian Ocean, but when the literature available is scarce we will mention studies available from other oceans. The information pertaining to each species is arranged by paragraphs. Nevertheless, accurate information is sometimes difficult to find. General descriptive characters, illustrations of diagnostic features for each species are given in appendix.