ABSTRACT
Sharks (Selachii) occur in all oceans, from coastal habitats (including up through some freshwater habitats) to oceanic waters, from the surface to depths of more than 3,000 metres (Priede et al, 2006). Sharks also display an amazing diversity of body sizes at maturity — from 17–20 cm for dwarf lantern sharks (Etmopterus perryi) to 1,250–1,400 cm for whale sharks (Rhincodon typus), as well as feeding modes — from planktivorous whale and basking sharks (Cetorhinus maximus) to apex predators like white sharks (Carcharodon carcharias). Most elasmobranchs (sharks and rays) and the related chimaeras are characterized by relatively low fecundity and productivity, slow growth, late age at maturity, large size at birth, high natural survivorship and a long life. Such biological characteristics have serious implications for the sustainability of elasmobranch fisheries. Not surprisingly, these species generally have limited capacity to sustain and recover from heavy fishing pressure, including both direct exploitation and incidental catches (or by-catch) (e.g. Dulvy et al, 2008).
