Insights into the Ecology and Movements of the Blacktip Reef Shark (<em>Carcharhinus melanopterus</em>)

A challenge in studying the natural behaviour of wild animals is the need for detailed observations spanning extended periods of time, which are particularly difficult to obtain in the case of sharks. As a result, tagging and remote sensing technologies are usually employed. In this study, 475 blacktip reef sharks (Carcharhinus melanopterus) were identified using direct underwater observation. Subsequent sightings of individual sharks were recorded at various locations along the north shore of Mo’orea Island over a period of 6.5 years. The key factors influencing their movements were the reproductive season and the lunar phase. In addition, tendencies to avoid turbulent regions and to leave the area after fishing mortality were observed. Significant variation existed between individuals. While some sharks left their ranges for only two weeks twice a year for mating and parturition, others were absent for months. Juveniles displayed high mobility prior to settling into a home range during the year before maturity, at the age of about 4 years. The understanding of such movements is important for the effective protection of sharks through the establishment of Marine Protected Areas and other conservation strategies.