Background/Aims
Scalloped hammerhead sharks (Sphyrna lewini) are listed as ‘Critically Endangered’ by the International Union for the Conservation of Nature (IUCN), with observed declines caused by overfishing and habitat degradation. Because of this, there is a pressing need to identify movement patterns and key habitats for the species, including breeding, nursery, and aggregation sites. While Unmanned Aerial Vehicles (UAVs) or drones, have been successfully used to monitor shark populations elsewhere, limited data exists on the seasonal movements of scalloped hammerhead sharks in southeastern Australia. This study aimed to investigate the frequency and factors influencing scalloped hammerhead sightings off southeast Queensland (SEQ) beaches, particularly focusing on the identification of important habitats.
Methods
The study reviewed footage from the Queensland SharkSmart drone trial (September 2020 to December 2024). Over 20,000 drone flights were logged, capturing sightings of scalloped hammerhead sharks across nine SEQ beaches. Environmental data, including month, visibility, time of day, and weather conditions, were collected to assess their impact on shark sightability using drones. Sightings were categorised by location and season to determine patterns of scalloped hammerhead shark movement and habitat use.
Results
This research identified key habitats used by scalloped hammerhead sharks, including aggregation sites and juvenile nursery areas along SEQ's coastline. Environmental factors, such as month and turbidity, were found to significantly influence the frequency of shark sightings. Scalloped hammerhead sharks were most commonly sighted during April and May in 2023 and 2024 at Burleigh Beach, suggesting the presence of seasonal aggregation patterns. The results indicate that specific areas of SEQ’s beaches are critical for the species' lifecycle and should be prioritised for conservation efforts.
Conclusion
The findings of this study significantly enhance our understanding of scalloped hammerhead shark habitat use in southeast Queensland. This research provides crucial data to inform coastal zone management and marine park planning, ensuring the protection of key habitats for this critically endangered species. Further monitoring and targeted conservation actions are essential to safeguard these areas for the long-term survival of the species.