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The design of ecological networks of marine protected areas (MPAs) is generally based on the identification of areas of high abundance for species of conservation concern or focal biodiversity targets. We discuss the applicability of this approach to marine top predators and contend that the design of comprehensive and effective MPA networks requires the following 7 principles: (1) the use of wildlife-habitat modelling and spatial mapping approaches to develop testable model predictions of species distribution and abundance; (2) the incorporation of life-history and behavioural data into the development of these predictive habitat models; (3) the explicit assessment of threats in the design and monitoring process for single-or multi-species MPAs; (4) the serious consideration of dynamic MPA designs to encompass species which use well-defined but spatially dynamic ocean features; (5) the integration of demographic assessment in MPA planning, allowing provision of advice to policy makers, ranging from no to full protection; (6) the clear articulation of management and monitoring plans allowing retrospective evaluation of MPA effectiveness; and (7) the adoption of an adaptive management approach, essential in the light of ongoing and anticipated ecosystem changes and species range shifts in response to climate change.

Many fishes make frequent ascents to surface waters and often show prolonged surface swimming following descents to deep water. This affinity for the surface is thought to be related to the recovery of body heat lost at depth. We tested this hypothesis using data from time-depth recorders deployed on four whale sharks (Rhincodon typus). We summarized vertical movements into bouts of dives and classified these into three main types, using cluster analysis. In addition to day and night 'bounce' dives where sharks rapidly descended and ascended, we found a third type: single deep (mean: 340 m), long (mean: 169 min) dives, occurring in daytime with extremely long post-dive surface durations (mean: 146 min). Only sharks that were not constrained by shallow bathymetry performed these dives. We found a negative relationship between the mean surface duration of dives in the bout and the mean minimum temperature of dives in the bout that is consistent with the hypothesis that thermoregulation was a major factor driving use of the surface. The relationship broke down when sharks were diving in mean minimum temperatures around 258C, suggesting that warmer waters did not incur a large metabolic cost for diving and that other factors may also influence surface use.

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