Assessing White Shark (Carcharodon carcharias) Behavior Along Coastal Beaches for Conservation-Focused Shark Mitigation

Operational Protocols for the Use of Drones in Marine Animal Research

“…Published research on sharks using drone-based methods has become commonplace in the scientific literature over the last five years. These studies have largely focused on detection and abundance estimates [19,29], and tracking and behavioural observations [25,[30][31][32][33][34][35]. Drones typically survey comparatively smaller spatial scales compared to manned aircraft [36,37], and while sharks may be rare in abundance [38], they are often easy to detect from drones if conditions are ideal [39,40].…”

“…This allows drone sampling to be highly useful for providing quantifiable aerial observations of sharks from relatively low altitudes without significant disturbance effects [29,31]. Drones have also proven useful for behavioural observations and fine-scale tracking of various shark species [30,31,42,47]. Typically, obtaining data on shark movement and behaviour has largely been conducted using boat-based observations [33,48,49], underwater video [50], or more commonly, satellite and/or acoustic tracking methods [51,52].…”

“…In addition, it is difficult to differentiate individual sharks from the air, so once a shark is lost from view, it is difficult to ascertain whether a subsequent sighting is the same individual or not, which can complicate analysis [48]. Due to the limitations of drone-based tracking, sharks are generally followed for up to tens of minutes [30,47]. In contrast, satellite tagging can track known individuals for long periods of time (up to years).…”

“…In common off-the-shelf multirotor drones, the combination of the inertia management unit, barometer and GPS/GLONASS positioning system, allows vertical and horizontal positioning precision of ±0.5 m and ±1.5 m, respectively [12]. Therefore, with the gimbal orientated in nadir (pointed directly down) and the drone positioned directly above, the position of the shark can be obtained as well as photogrammetric measurements [30]. Regular calibrations of the inertia management unit and the gimbal are highly recommended to maintain the highest achievable measurement precision.…”

“…The lower the drone, the greater the potential relative error margin of the recorded altitude of the drone (since the error is constant), but the higher the resolution for pinpointing the extremities of the shark. For example, Raoult, et al [47] tracked <1.25 m (total length) Epaulette sharks (Hemiscyllium ocellatum) and >1.25 m reef sharks (Carcharhinus melanopterus, Negaprion acutidens) in a shallow reef lagoon using a <2 kg drone with a 94 • field-of-view camera at 2-5 m altitude; whereas Colefax, et al [30] tracked 2-4 m white sharks (Carcharodon carcharias) along coastal exposed beaches using a similar a <2 kg drone with a 94 • field-of-view camera, but tracked at 20-25 m to better observe behavioural interactions and record length estimates.…”