Fine scale movements and activity areas of white sharks (Carcharodon carcharias) in Mossel Bay, South Africa

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Authors

Jewell, Oliver Joseph David
Johnson, Ryan Lloyd
Gennari, Enrico
Bester, Marthan Nieuwoudt

Journal Title

Journal ISSN

Volume Title

Publisher

Springer

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.

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Keywords

Acoustic telemetry, Manual tracking, Home range, Kernel analysis, Habitat use, White sharks

Sustainable Development Goals

Citation

Jewell, OJD, Johnson, RL, Gennari, E & Bester, MN 2013, 'Fine scale movements and activity areas of white sharks (Carcharodon carcharias) in Mossel Bay, South Africa', Environmental Biology of Fishes, vol. 96, no. 7, pp. 881-894.