Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Network-based analyses of elasmobranch behaviour (#19)

Robert J Y Perryman 1 , Culum Brown 1 , Johann Mourier 2 , Chris Rohner 3
  1. Macquarie University, Sydney, New South Wales, Australia
  2. Plateforme Marine Stella Mare, Universite de Corse Pasquale Paoli, Biguglia, France
  3. Marine Megafauna Foundation, Truckee, California

Knowledge of spatial ecology is vital for the conservation of wide-ranging marine species. Network-based analyses of movements and social interactions are increasingly used to provide biologically realistic, quantitative descriptions of the behaviour of individuals, groups and populations. In the marine environment, the most practical and economical method for simultaneous tracking of large numbers of individuals is passive acoustic telemetry (PAT), which records the presence of individuals at aggregation sites. We discuss different methods for network-based analysis of PAT data, and demonstrate application of these to a range of phylogenetically and behaviourally distinct elasmobranch species.

We compare the prevalence and longevity of interactions, and dynamics of co-occurrence patterns in whale sharks (Rhincodon typus) and white sharks (Carcharodon carcharias). We test the extent to which the structure of associations between sharks depends on passive aggregation (due to environmental factors), versus active social grouping, by randomization of movement tracks within individuals at a range of temporal scales.

We employ a different method using Bayesian inference to study the social dynamics of reef manta rays (Mobula alfredi). Here we found that social affiliations were assorted into spatially-defined communities that remained stable over time periods of weeks to months. Inter-individual variability in detection profiles was correlated with social network metrics, suggesting that certain individuals, groups and locations are likely to be important to the integrity of social networks.