Shark leaders or followers? Recent Study Reveals Hidden Coordinated Shark Behaviours

A new study from the Sequeira Lab just published in Movement Ecology has revealed that some sharks follow leaders — thanks to a collaboration between our lab leader  Ana Sequeira with Spanish physicists Víctor M. Eguíluz and Juan Fernández-Gracia from the Instituto de Física Interdisciplinar y Sistemas Complejos (IFISC), whose background in complex systems and network theory played a pivotal role in shaping the analytical framework.

The research was led by Nils Kreuter a PhD student at the Australian National University and used acoustic telemetry data to design a novel method to detect leader-follower dynamics. This approach builds on earlier theoretical work by Fernández-Gracia and Eguíluz, which was adapted and refined to suit the challenges of analysing data from acoustically tracked grey reef, blacktip reef, and tiger sharks. By analyzing lag-time patterns between detections of tagged sharks at underwater receivers, the study found that grey reef sharks formed leader-follower networks at eight locations, with larger females more likely to lead. Blacktip reef sharks showed similar behaviours at three locations, with larger males taking the lead. And tiger sharks showed no evidence of leader-follower dynamics.

Understanding shark coordinated (or social) behaviour has important implications for conservation. If certain individuals play key roles in group dynamics, their removal could disrupt networks and affect population stability. The method, rooted in complex systems theory, demonstrates how interdisciplinary partnerships can unlock new insights from existing data. The study also demonstrates how existing telemetry data can be repurposed to uncover hidden social patterns, offering a powerful tool for marine ecologists.

Thanks to Victor and Juan for their continued support and long-standing collaboration with the Sequeira Lab Group, and well done to Nils for completing this work.