Pelagic or insular? Genetic differentiation of rough-toothed dolphins in the Society Islands, French Polynesia

► We investigated population dynamics of a pelagic dolphin in the Society Islands. ► Photographic and genetic recaptures of Steno bredanensis suggest island site fidelity. ► Strong genetic structure was found between two neighbour islands. ► This species forms small insular communities pointing out conservation issues. ► Other pelagic species of dolphins may follow this pattern near oceanic islands.