Scale of shark and ray movements and its importance in spatial management success

Movements and dispersal capacities of sharks and rays can be characterised over a continuum between highly site attached species with very limited dispersal capacities to highly mobile roamers with a capacity to disperse over... [ view full abstract ]

Movements and dispersal capacities of sharks and rays can be characterised over a continuum between highly site attached species with very limited dispersal capacities to highly mobile roamers with a capacity to disperse over great distances. Understanding where species lie within this continuum can help assess the effectiveness of spatial management policy, like Marine Protected Areas (MPAs) and Shark Sanctuaries. Although larger spatial closures are known to be more effective in protecting species that disperse large distances, closing off large expanses of open ocean may not be practical or effective spatial management in many regions of the world. In these cases, designing a network of smaller, carefully spaced MPAs may provide just as much benefit as expansive closures. Here we characterise the scale and capacity of movements in sharks and rays which can be used to better inform the design of spatial management policies.

We conducted a global, multi-species meta-analysis of shark and ray home range size and dispersal capacity using movement data obtained from fisheries mark-recapture records, acoustic and satellite telemetry datasets. Dispersal capacities for 47 shark and 17 ray species were characterized using dispersal kernels. Dispersal capacities for species where tracking or mark-recapture data was not available were imputed using dispersal records, home range estimates, biological and phylogenetic attributes extracted from previous literature. Here we demonstrate that understanding species-specific dispersal capacities can be used to model the ideal number, size and spacing of spatial closures needed to maximize the success of MPA networks for sharks and rays.