Are wobbegongs social?: social networks of the spotted wobbegong shark (orectolobus maculatus) in a small marine protected area

Many shark species form groups, however the drivers of this behaviour are not well understood. Previously it was thought that aggregations may be a function of resource availability or phenological behaviours, but recent studies have suggested that sharks display preferences in their associations with conspecifics and that complex social networks may underpin their movement patterns, demographic distribution and fitness. This study used a network approach to investigate patterns of sociality of a demersal predator, the spotted wobbegong shark, in a small marine reserve. Spatial data obtained from fine-scale passive acoustic telemetry were used to show that some sharks display preferences in their associations, many of which persisted after sharks returned to the reserve from their seasonal migration. These relationships were not exclusive, with some sharks forming associations with multiple individuals. Patterns were evident at the dyadic level, but limited evidence was found of a stable community or network structure. It appears that the species is not primarily gregarious but that benefits may be gained by maintaining a level of familiarity with a limited number of conspecifics. The composition of groups in terms of individual attributes (sex, size and familiarity) suggested that non-social aggregative behaviour was not a strong influence on association patterns. Site fidelity and home range overlap were also found to only marginally influence these associations. This suggests that the observed relationships can be explained, at least in part, by genuine social affiliation and that anthropogenic influences on the population may have more complex impacts than previously thought.