Through the camera lens: a window into the underwater behaviour of white sharks (Carcharodon carcharias)

Context Observations of terrestrial animals in their natural ecosystems have formed the foundation for many hypothesis-driven studies. Aims Observing animals in the marine environment is logistically more challenging and comparatively scarce. Underwater camera technologies provide new opportunities to document animal behaviour, particularly for large marine predators. Methods We deployed animal-borne cameras on 42 white sharks, Carcharodon carcharias (35 at Seal Island, South Africa, and seven at the Neptune Islands, Australia), recording 112 h of usable footage, complemented by opportunistic observations from diver-operated cameras, to gain insights into the subsurface behaviour of this high-order predator. Our large number of deployments identified new behaviours and provided further insights into the behavioural ecology of white sharks at two aggregation sites near pinniped colonies. Key results Gaping was the most frequently observed behaviour, but its purpose remains speculative. From 75.6 h of footage in South Africa, predatory events were recorded on 46 occasions (0.61 events h−1), consisting of 26 chases, 11 predation attempts and 9 successful predations. By contrast, only 1 predation event was observed in South Australia across 36.5 h of footage (0.03 events h−1). We documented a range of behaviours, including seal mobbing and interactions with jellyfish, fish, rays and seabirds. Footage from diver-operated cameras also captured, for the first time, mobbing behaviour by southern bluefin tuna (Thunnus maccoyii) and the intestinal eversion of a white shark. White sharks also exhibited inquisitive behaviour towards various objects, including kelp and a metal can on the seafloor. Only two intraspecific interactions (away from cage-diving operators) were recorded, supporting the perception that white sharks are largely solitary. Conclusions Our observations demonstrated that white sharks exhibit a diverse range of behaviours, including hunting tactics and exploratory behaviour not previously reported. The investigatory behaviour of white sharks highlighted their curiosity and exploratory tendencies, including toward non-food objects, suggesting that interactions may not always be driven by predatory intent. Implications With advances in camera technologies such as drones, remote underwater vehicles, and animal-borne cameras with biologgers, future studies can combine camera-based methods to improve behavioural recording and further open a window into the lives of large sharks and their interactions with the environment.