Ethological Insights into the Ecology and Movements of the Blacktip Reef Shark (<i>Carcharhinus melanopterus</i>) in an Undisturbed Reef Community<b></b>

A challenge in the ethological study of wild animals is the need for detailed, long-term observations, which work is particularly difficult in the case of sharks. Consequently, most research relies on tagging and remote sensing technologies to provide presence-absence data in which the behavioural and social context is lacking. In contrast, this study employed direct underwater observation to document the movements of 475 identified blacktip reef sharks (Carcharhinus melanopterus) along the north shore of Mo’orea Island, French Polynesia. Over 6.5 years, repeated sightings across multiple locations revealed movement as a defining feature of C. melanopterus behaviour; juveniles demonstrated substantial mobility even at an early age. The principal drivers were the reproductive season and the lunar phase. A tendency to avoid turbulent regions and absences linked to fishing mortality were also evident. Individual variation was pronounced, reflecting behavioural flexibility and complex spatial ecology. By linking observed movements to behavioural context, this ethological approach complements telemetry-based studies and highlights the need for integrative research strategies. These findings also underline the importance of integrating both site fidelity and wide-ranging roaming behaviour into conservation strategies. Effective protection—including through the design of Marine Protected Areas—must account for the breadth of their movements to ensure the persistence of populations and the resilience of coral reef ecosystems. Ultimately, given the continuing threats from the shark fin trade and illegal, unreported, and unregulated fishing, a total ban on the international trade in sharks, rays, chimaeras and their parts remains urgently needed.