European Ocean Biodiversity Information System

Eighteen individuals were fitted with transponders and tracked from Réunion Island (21.2°S, 55.3°E) in order to investigate movements and diving patterns. Nine turtles swam north towards Oman (20.5°N, 58.8°E), where one of the world’s largest rookeries of loggerheads is located. Three individuals travelled south towards South-Africa and Madagascar, countries that also host loggerhead nesting grounds. Fourteen of the transmitters relayed diving profiles. A dichotomy between diurnal and nocturnal diving behavior was observed. A greater number of shorter dives occurred during the day. Diving behavior also differed according to movement behavior as individuals spent more time in subsurface waters (<10 m) during transit phases. The study provides an improved understanding of the oceanic movements and diving behavior of juvenile loggerheads. The results address a significant gap in the understanding of loggerhead oceanic movements and may help with the conservation of the species.