Shark personality within the predator-prey context

Consistent behavioural variability between individual animals (‘personalities’) and behavioural correlations (‘syndromes’) are widespread across the animal kingdom, and are likely of major conservation and ecological importance. Although there has been growing interest in understanding how animal personalities influence fitness and are maintained over time, the effects of this phenomenon on complex ecological processes like predator-prey interactions are still poorly understood, especially for large marine vertebrates like sharks. The gap in our understanding is particularly concerning due to the worldwide decline in shark population numbers, threatened by fishing and environmental changes. In this thesis, I first describe the physiological response to capture in endemic Southern African catsharks, and observe how capture stress significantly lowered pH and K+ , while it severely increased lactate and pCO2 concentrations in their peripheral circulation. I then present novel evidence that a marine mesopredator, the dark shyshark, and a marine apex predator, the white shark, show consistent inter-individual variability in hunting and movement behaviour within the foraging landscape, that are not simply due to individual differences in hunger. Dark shysharks also showed individuality in coping styles, and repeatability in anti-predator responses. Their behaviour was further constrained by syndromes, although individuals appeared to maintain a certain level of behavioural plasticity in response to their social environment. Our results have important implications for public perception of sharks, and suggest that personality will directly affect shark fitness by mediating foraging behaviour and trophic interactions with other species. If personality is likely to have an effect on marine ecosystems as a whole, considering how sharks, through predation, have important roles in shaping prey populations, then its consequences on shark fitness should be included in conservation strategies for these species.