After a series of shark attacks along the northern NSW coast, the state government committed $16 million over 5 years to research shark detection and mitigation measures, as well as to understand their movements and what oceanographic processes correlate with areas of high shark abundance.
Part of this funding, together with a Research Attraction and Acceleration Program (RAAP) grant awarded to the Sydney Institute of Marine Science (SIMS), was dedicated to a postdoc position to determine the main oceanographic drivers of the movement of ‘potentially dangerous’ sharks (bull, white and tiger sharks) and to subsequently build predictive models to help shark mitigation measures.
Dr Kate Lee, based at SIMS, has been analysing both long-term datasets of shark catches from the NSW shark meshing program (more information at https://www.dpi.nsw.gov.au/fishing/sharks/management/shark-meshing-bather-protection-program) and shorter-term tracking datasets (of bull and white sharks) and aerial surveys conducted by NSW DPI.
Using satellite data from the Australian Ocean Data Network (AODN) Portal, along with physical datasets from NSW-IMOS partners, this research has identified species-specific drivers highlighting the complexity of mitigating risks from multiple shark species.
Bull sharks are only present along the NSW coast in the summer and early autumn, when the coastal waters are warmest, and annually return to where they were tagged. In contrast, white sharks are most abundant during the spring and early summer when water temperatures are around 17-18°C. Surprisingly, neither of these species are associated with mesoscale eddies that dominate this region of the East Australian Current. However, further analyses still need to be conducted.
IMOS has been invaluable to conduct this work. The ready availability of satellite and physical datasets on the AODN Portal have made integrating the animal and oceanographic data seamless. Furthermore, the number of researchers contributing to the IMOS Animal Tracking Facility database has allowed the movements of tagged sharks to be monitored along the entire NSW coast.
The results from this project, along with the data available from the AODN Portal, will be integrated into future shark mitigation measures and help identify periods of high shark abundance along this populated coastline.
This article was written by Kate Lee.