Shark aggregations underpin conservation but where are they and when do they occur?
Naima Andrea López | March 2021
Fieldwork
This week, PhD candidate Naima Andrea López, concluded the final fieldwork campaign within the Shoalwater Islands Marine Park where she is studying shark aggregations using both drones and baited remote underwater video systems (BRUVS). Over the last two austral summers, Naima has been conducting weekly aerial surveys within the Shoalwater Islands MP and included monthly BRUVS surveys during this last summer 2020-2021. Naima’s PhD fieldwork comes to an end after 4 intense months of surveys supported by an incredible group of volunteers.
Aerial surveys took place over shallow waters of the marine park at a constant speed and altitude under appropriate visual conditions to ensure optimal detection of the sharks. Each survey comprised several standardised transects across different management zones of the marine park which will allow her to obtain distribution, diversity, and estimations of body size parameters (through photogrammetry analysis), and to investigate the correlation with seasonality (time of the year), bathymetry, and remote sensing environmental parameters to model and predict the occurrence of such aggregations on a regional scale. In total, over 190 flights were completed during the two seasons. The high-resolution video footage obtained will also contribute to the study of movement behaviour of the aggregating sharks.
Over December 2020, January and March 2021, the team conducted daily trips to the Shoalwater Islands MP onboard the research vessel Ecklonia, were they deployed seabed BRUVS to document the diversity, abundance, size, biomass and behaviour of marine wildlife across all management zones of the marine park. In total, they conducted 3 BRUVS expeditions obtaining over 240 hours of video footage. Data obtained from BRUVS analysis will inform on the fish communities associated with the aggregations and will be used to interpret drone footage, which will be the base to model potential aggregation locations within the coast of Western Australia.
This research aims to inform strategies for the protection of the critically endangered scalloped hammerhead at their aggregation sites in Western Australia.
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Shoalwater
Aerial view of the Shoalwater Islands Marine Park, area of study
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Drones
Aerial-drone image of the aggregating hammerhead sharks (Sphyrna lewini)
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BRUVS
Deploying seabed BRUVS from Ecklonia with enthusiastic volunteers (Tamara Waddell)
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Tiger shark
Underwater BRUVS image showcasing a tiger shark (Galeocerdo cuvier)
FUNDING & ACKNOWLEDGEMENTS
The BRUVS expedition was undertaken aboard the UWA vessel Ecklonia. This research was supported by the Australian Government RTP Scholarship, The Jock Clough Marine Foundation through the Oceans Institute Robson and Robertson Award, and The Holsworth Wildlife Research Endowment & The Ecological Society of Australia.