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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13572

Oceanographic conditions associated with white shark (Carcharodon carcharias) habitat use along eastern Australia

K. A. Lee*, P. A. Butcher, R. G. Harcourt, T. A. Patterson, V. M. Peddemors, M. Roughan, D. Harasti, A. F. Smoothey, R. W. Bradford

*Corresponding author:

ABSTRACT: Management of species with wide-ranging migrations is a complex issue; made more challenging when the species is both protected and poses a risk to humans. Understanding the oceanic conditions associated with shark habitat use can help develop mitigation strategies or warning systems that meet both conservation and human safety objectives. Using satellite tracks from 77 juvenile and sub-adult white sharks tagged over 10 years, we modelled individual movement patterns using Hidden Markov Models, and applied Generalised Additive Mixed Models to explore correlations between movement patterns (presence/absence, habitat selection and behavioural state) and oceanographic and bathymetric variables. White sharks used the whole of the continental shelf, down to depths of 350 m on the continental slope. Sharks were present over a wide range of sea surface temperatures (SST; 10-27°C) with highest probability of occurring ~20°C. However, the number of average daily tag positions was greatest when SST was between 14 and 18°C, and sharks were more likely to exhibit area restricted movement when SST was between ~19 and 23°C. Sharks were more likely to be present and selected habitats in productive areas with moderate to high surface chlorophyll-a concentrations, as well as thermal and productivity fronts. Although mesoscale eddies did not influence the likelihood of individuals being present in an area, there was a higher density of sharks in cold-core eddies compared to warm-core eddies. This study indicates that white shark presence and dispersal may be linked, perhaps via prey distribution, to oceanic conditions potentially assisting development of suitable shark bite mitigation strategies.