Drone monitoring of endangered scalloped hammerhead shark Sphyrna lewini movements and habitat use on a dynamic urbanised coastline in Australia

Maddison Cross; Bonnie Holmes; Matthew N. McMillan; Johan Gustafson; Tracey Scott-Holland; Jonathan D Mitchell

doi:10.21203/rs.3.rs-8769949/v1

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Drone monitoring of endangered scalloped hammerhead shark Sphyrna lewini movements and habitat use on a dynamic urbanised coastline in Australia

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Drone monitoring of endangered scalloped hammerhead shark Sphyrna lewini movements and habitat use on a dynamic urbanised coastline in Australia

Maddison Cross, Bonnie Holmes, Matthew N. McMillan, Johan Gustafson, Tracey Scott-Holland and Jonathan D Mitchell

Research Square, Vol.10 February 2026

Research Square Group

2026

DOI: https://doi.org/10.21203/rs.3.rs-8769949/v1

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Abstract

aerial surveys

spatial ecology

critical habitat

juvenile sharks

elasmobranchs

Many elasmobranch species face increasing pressures from overfishing, habitat degradation, and coastal development, yet their movement ecology remains poorly understood. Unmanned Aerial Vehicles or drones offer a non-invasive method to study the distribution and habitat use of species frequenting inshore areas. Scalloped hammerhead sharks (Sphyrna lewini), listed as Critically Endangered on the International Union for the Conservation of Nature (IUCN) Red List, have experienced global population declines prompting the need for research that identifies key habitats, including nursery and aggregation sites. This study analysed archived footage from the Queensland SharkSmart drone program at nine beaches in southeast Queensland between September 2020 and December 2024. The frequency of scalloped hammerhead sightings was quantified, along with the influence of environmental, biotic, and operational variables on sightability. Ninety sightings were recorded, primarily between April and June. Sightings were significantly influenced by turbidity, presence of other fauna, time of day, month, and location. Aggregations of up to 80 juvenile sharks (estimated mean total length 109 cm ± 25 cm) were observed at Burleigh Beach, with additional sightings at Noosa Main Beach. These findings provide new insights into the species’ spatial ecology in southeast Queensland, Australia and demonstrate the value of drone monitoring for conservation and spatial management.

Details

Title: Drone monitoring of endangered scalloped hammerhead shark Sphyrna lewini movements and habitat use on a dynamic urbanised coastline in Australia
Authors: Maddison Cross - University of the Sunshine Coast
Bonnie Holmes - University of the Sunshine Coast
Matthew N. McMillan - Queensland Department of Primary Industries and Fisheries
Johan Gustafson - University of the Sunshine Coast
Tracey Scott-Holland - Department of Primary Industries
Jonathan D Mitchell - Department of Primary Industries
Publication details: Research Square, Vol.10 February 2026
Publisher: Research Square Group
Date published: 2026
DOI: 10.21203/rs.3.rs-8769949/v1
ISSN: 2693-5015
Copyright note: This work is licensed under a CC BY 4.0 License
Data Availability: Corres. author can provide the datasets used in this study upon reasonable request, although footage which contains images of people is considered confidential and cannot be made publicly available.
Grant note: Although this research did not receive external funding, the SharkSmart drone program is funded by the Queensland Government.
Organisation Unit: School of Science, Technology and Engineering
Language: English
Record Identifier: 991214551602621
Output Type: Preprint

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