Variability in the burst behaviour of the white shark (Carcharodon carcharias)

Context Predators and prey alike have evolved to maximise their chances of survival by adapting their behaviour and movement over time and across situations. Large marine predators such as white sharks (Carcharodon carcharias) exhibit variability in foraging strategies based on prey and surrounding habitat. White shark predation on fast, mobile prey like pinnipeds is often characterised by strong acceleration that can end in a breach. Aims We aim to build our understanding of white shark foraging behaviour at aggregations around pinniped colonies and highlight behavioural variability in a top marine predator. Methods We deployed animal-borne cameras and accelerometers on 19 white sharks at the Neptune Islands and Liguanea Island, South Australia, and compared two methods for identifying burst events: random forest machine learning model trained using varying numbers of predictor variables, where eight predictors was the most parsimonious, and a threshold method using two acceleration metrics. Burst events were characterised (i.e. starting depth, speed, acceleration, and time of day) and compared across three contexts: (1) cage-diving operating and (2) not operating around a pinniped colony, and (3) when sharks were away from the pinniped colony. Key results The frequency of burst events was nine-fold higher during cage-diving operations. However, these events were characterised by slower swim speeds and lower acceleration than other burst events, with primarily horizontal or near-horizontal approaches compared to other periods. Only three burst events culminated at the surface or resulted in a breach when cage-diving was not operating or when sharks were away from the islands, compared to 11 when surface cage-diving was occurring. The frequency of burst events when sharks were away from the cage-diving site was highest at dawn with no events at dusk. Conclusion White shark foraging behaviour likely reflects prey fields and highlights the diversity in strategies used by white sharks globally. Implications Our study enhances our understanding of white sharks’ behaviour and variability in foraging strategies both at and away from pinniped colonies.