, 1984). This heterogeneity of distribution by tuna species is exploited by the use of ABT-199 cost man-made fish aggregation

devices which apply further pressure on populations by extracting immature individuals (Cayre, 1991 and Itano and Holland, 2000). Shoaling behaviour is also common in other ocean predators such as pelagic sharks (Au, 1991) and assemblages of these species have been observed at seamounts and offshore islands in the eastern tropical Pacific (Hearn et al., 2010). This natural heterogeneity in distribution could potentially enhance preservation of migratory species using strategically located pelagic marine reserves. Studies have already demonstrated that marine reserves can benefit pelagic species that exhibit highly mobile behaviours, albeit to a lesser extent than sedentary species (reviewed in Game et al., 2009). In addition, it has been shown that (1) in fisheries high throughput screening management, the phrase ’highly migratory’ often has little biological meaning, with studies of tuna mobility demonstrating they would benefit from national-level closures (Sibert and Hampton, 2003); (2) persistence and, thus, predictability of some habitat features within the pelagic realm does occur (Alpine, 2005, Baum et al., 2003, Etnoyer et al., 2004, Hyrenbach et al., 2000 and Worm et al., 2003); (3) positive, measurable reserve effects on pelagic

populations exist (Baum et al., 2003, Hyrenbach et al., 2002, Jensen et al., 2010, Roberts and Sargant, 2002, Worm et al., 2003 and Worm et al., 2005; and (4) migratory species can benefit from no-take marine reserves (Beare et al., 2010, Jensen et al., 2010, Palumbi, 2004 and Polunin and Roberts, 1993). In fact, it is now believed that pelagic MPAs are an important tool in the planet’s last frontier of conservation management (Game et al.,

2009) and are rapidly becoming a reality (Pala, 2009), although some of the challenges relating to their implementation may be both costly and difficult (Kaplan et al., 2010). Large MPAs are considered necessary to protect migratory species such as large pelagic fish and marine mammals (Wood et al., 2008) as well as offsetting the concentration of fishing effort outside them (Walters, 2000) and maintaining ecological value (Nelson and Bradner, 2010). Partial protection for migratory species can not be considered futile, Carnitine palmitoyltransferase II although a more coordinated approach for protection is preferable as no-take marine reserves should be combined with areas of limited fishing effort (Pauly et al., 2002). Optimisation models have suggested that tuna fisheries could even gain some economic efficiencies by closing large areas, provided overall effort is reduced and shifted into high value geographic areas (Ahrens, 2010). In addition, the presence of pelagic MPAs has also been shown to leverage improved marine management in adjacent areas (Notarbatolo di Sciara et al., 2008).