Are some sharks more social than others? Short- and long-term consistencies in the social behavior of juvenile lemon sharks

Abstract

Abstract: Despite substantial research interest in understanding individual-level consistency in behavioral attributes, significant knowledge gaps remain across traits and taxa. For example, relatively few studies have looked at social personality in large marine species such as elasmobranchs and whether or not individual differences in behavior are maintained in unstable social groups (i.e., fission-fusion dynamics). However, it is important to investigate this topic in other model species than the usually small species with short generation times typically investigated in these areas of behavioral ecology. Indeed, studies on ecologically diverse taxa could provide mechanistic insights into the emergence and maintenance of animal personality and dynamics of social groups in animals. In addition, understanding social behavior at the group- and individual-level could improve conservation management of these large animals with long generation times (e.g., removal of particular behavioral types by fisheries practices). Here, we investigated consistent individual differences in sociability in wild juvenile lemon sharks (Negaprion brevirostris) over both short- (4 to 18 days) and long-term (4 months) sampling periods. Individual sharks were observed in social groups and scored according to the number of social interactions performed during observations. Despite variable individual group compositions between repeated trials, sharks showed consistent individual differences in their social behavior over both time scales. These results suggest reduced plasticity and highlight individuality as an important explanatory variable for the social dynamics of juvenile lemon sharks. In addition, long-term stability observed in this wild population demonstrates the importance of personality in the daily behavioral repertoire of juvenile lemon sharks. Our results are discussed in the context of other shark studies and taxonomic groups and potential avenues for future research are proposed. Significance statement: This study investigated the social personality axis in a wild population of juvenile lemon sharks. First, we demonstrated consistent individual differences in their tendency to socialize. Second, we showed that individuals maintained their differences over a four-month period in the wild. Finally, we found that individual social behaviors were maintained despite being tested in variable group compositions. These results highlight the importance of individuality in the social dynamic of a poorly investigated animal and suggest personality as an important aspect of juvenile lemon sharks’ everyday life over a relatively long-term period.