Individual personality and lateralization differences in Port Jackson sharks (Heterodontus portusjacksoni)

Despite hundreds of studies on personality in fishes, there remains a striking lack of research on personality in the elasmobranchs. Given the heritability of personality and elasmobranchs’ extensive evolutionary history, it is unlikely that personality has been evolutionarily stagnant in elasmobranchs. Personality influences every day risk-reward decisions that cause variation in individual life history fitness traits, and is shown to link to various aspects of behaviour and cognition, such as cerebral lateralization. Studying personality and lateralization in elasmobranchs is crucial to understanding species flexibility in coping with a changing environment. Using boldness and stress reactivity assays we tested for individual personality differences in Port Jackson sharks (Heterodontus portusjacksoni). Additionally, we aimed to examine the expression of cerebral lateralization using swimming directionality and examined how inter-individual variation relates to personality in sharks. Our results show individual personality differences that are consistent through time, as well as large inter-individual variation in lateralization strength and direction. Little evidence was found that personality relates to lateralization, but stress reactivity was found to correlate with strength of lateralization. These results demonstrate individual personality and lateralization differences in sharks for the first time, suggesting ancient evolutionary origins of personality and lateralization in vertebrates.