Background/Aims: Efficient fish stock assessment provides critical data for the formulation of evidence-based fisheries management decisions. However, requisite tools for monitoring fish populations may be impeded by the high cost of research expeditions, with significant time demands, and spatially and temporally dependent logistical constraints. Consequently, remote sensing techniques are becoming increasingly integrated into marine fisheries for rapid, less costly, yet intensive data gathering on stock biomass, assemblages and distribution. Here, we extend the possibilities of remote sensing applications in fisheries by exploring the suitability of a consumer-grade unmanned aerial vehicle (UAV) for short-drift drone surveys of coastal pelagic fish assemblages in near-shore tropical coastal habitats.
Methods: We develop and test a rapid UAV-based methodology for coastal pelagic fish detection and species identification. Using a point-based suitability scoring, we make recommendations for camera angle and altitude optimisations for accurate in-situ fish detection and subsequent identification.
Results: For optimal fish detection, drone deployment at altitudes ranging from 4 m to 10m with camera angled at the nadir position (90°) produces the best accuracy in coastal pelagic fish surveys. A 60° camera angle will effectively mitigate sun glint during sunny days but not optimal. A test survey with the proposed method effectively revealed the most dominant fish species across selected coastal sites in Townsville, Queensland, demonstrating the assemblage patterns for Liza vaigiensis (diamondscale mullet), Crenumugil seheli (bluespot mullet), and Tylosurus sp. (crocodile longtom).
Conclusion: Our findings advocate that drone technology are effective in detecting coastal pelagic fish at lower flight altitudes. A deployment and implementation workflow are provided for adaptation in similar shallow habitats, offering a practical framework for integrating UAVs in coastal fish monitoring.