Abstract:
Previous work on white sharks indicate the species show seasonally limited
movement patters, at certain aggregation sites small areas may play vital roles in the
life history of a large amount of the population. Acoustic telemetry was used to
estimate habitat use of white sharks, Carcharodon carcharias, while aggregating at
Mossel Bay, South Africa. Total range of all shark tracks combined accumulated 782
hrs and covered an area of 93.5 km2 however, within this range, sharks were found to
highly utilise a core habitat (50% Kernel, K50) of just 1.05 km2 over a reef system
adjacent to a river mouth. Individual tracks revealed additional core habitats, some of
which were previously undocumented and one adjacent to a commercial harbor. Much
was found to be dependent on the size of the shark, with larger sharks (>400cm)
occupying smaller activity areas than sub-adult (300-399 cm) and juvenile (<300 cm)
conspecifics, while Index of Reuse (IOR) and Index of Shared Space (IOSS) were
both found to increase with shark size. Such results provide evidence that larger white
sharks are more selective in habitat use, which indicates they have greater experience
within aggregation sites. Furthermore, the focused nature of foraging means spatially
restricted management strategies would offer a powerful tool to aid enforcement of
current protective legislation for the white shark in similar environments of limited
resources and capacity.
