From Passive Drift to Olfactory Detection? A Late‐Stage Oceanic Juvenile Hawksbill's 9000‐km Journey Across the Western Indian Ocean

ABSTRACT

The mechanisms underlying the transition of juvenile sea turtles from oceanic to neritic habitats remain poorly understood, as the oceanic stage is rarely observed directly. Here, we report a 201‐day satellite track of a juvenile hawksbill turtle ( Eretmochelys imbricata , curved carapace length of 38 cm) that traveled 9129 km from the Mozambique Channel to Huvadhu Atoll, Maldives. Current reanalysis data indicate that 74% of this distance resulted from passive transport by regional ocean currents. However, upon approaching within 50 km of the atoll, the turtle showed a marked, active course correction, swimming against weak currents while positioned downwind and downstream of the atoll, a low‐lying landform (~1 m above sea level) that would have been invisible by eye at such a distance. This pattern raises the possibility of olfactory detection of the atoll and provides, to our knowledge, a first indication of olfactory‐based island detection guiding habitat recruitment in a juvenile turtle, a mechanism previously documented only in breeding females. This track suggests a potential two‐scale process of oceanic‐to‐neritic habitat transition: a broadly stochastic oceanic phase shaped by passive dispersal, followed by fine‐scale, sensory‐guided settlement once the turtle nears a suitable habitat.