Movement behaviour of clinically treated olive ridleys released from Maldives

Olive ridley turtles Lepidochelys olivacea in the Indian Ocean face significant anthropogenic threats, particularly from entanglement in ghost nets. As olive ridley turtles are a pelagic species, there is an opportunity to understand the movement behaviour and utilisation distribution (UD) of olive ridleys after being clinically treated for injuries related to entanglement. We documented the movement patterns and UDs of 5 rehabilitated olive ridley turtles post-release from the Maldives. Olive ridleys were rescued from ghost nets, clinically treated, and released from Dhuni Kolhu, Baa Atoll, Maldives, after being fitted with SeaTrkr-4375-4 (Telonics). Data were analysed using a movement persistence model to calculate movement persistence (γ) to determine possible behaviours along their tracks. In addition, satellite tracks were put through a dynamic Brownian bridge movement model (dBBMM) to identify 50% UDs within the Indian Ocean. Olive ridleys were tracked for 28-230 d and showed variation in both movement patterns and UDs between individuals. Most individuals displayed transitory behaviour (γ > 0.6) rather than behaviour that could be interpreted as area-restricted movement, though areas where γ was low were spatially aligned where 50% UDs were found. All olive ridley turtles moved in different directions, which could indicate that their points of entanglement prior to drifting into the Maldives were from distant regions. This wide-spread dispersal of olive ridleys within the northern Indian Ocean highlights that exposure to ghost gear (and associated impacts) may be widely distributed within this ocean basin.