Swimming Behaviour and Energetics of Free-ranging Sharks: New Directions in Movement Analysis

There is now a general agreement that sharks, and pelagic sharks in particular, are facing widespread declines in population level due to fishing activity (Pauly et al., 2003). Recent studies suggest dramatic reductions in relative abundance of up to 80% have occurred in as little as 15 years for some species (Baum et al., 2003; Myers et al., 2006), trends most likely linked to greater target catch and bycatch rates fuelled by increased demand for shark fins and meat for human consumption. Although some fisheries assessments indicate less pronounced declines for large pelagic (Sibert et al., 2006) and coastal sharks (Burgess et al., 2006), undoubtedly they are particularly susceptible to over-harvesting on account of slow growth rates, late age at maturity and relatively low fecundity. Many pelagic sharks are now red-listed by the World 13