Inter-nesting habitat use by green turtles Chelonia mydas in the Great Barrier Reef

ABSTRACT: Understanding green turtle habitat use during the nesting season is important for informing management decisions relating to green turtles and ecosystems that support them. Despite patterns such as migration being described, few studies investigate behaviour during the inter-nesting period. This research aims to describe and quantify the spatial distribution patterns of green turtles during 2 nesting seasons on Raine Island in the northern Great Barrier Reef. Satellite telemetry data were used to analyse the inter-nesting movements and patterns of green turtles in 2017 (n = 19) and 2018 (n = 20). The inter-nesting period ranged from 51 to 100 d (76.33 ± 15.98 d) across both seasons. The average inter-nesting area of individual turtles did not differ between nesting seasons (2017: 12.31 ± 13.22 km², 2018: 12.01 ± 21.92 km²). In addition, it was established that 39 individuals are a sufficient sample size to describe the spatial distribution. Approximately half of the tracked individuals remained at the same reef for their entire inter-nesting season (n = 19), and half used habitat on nearby reefs (n = 20). Most turtles showed fidelity to Raine Island as a nesting site (n = 37), laying all their clutches on the island. However, 2 individuals travelled 479 and 337 km during the inter-nesting period. This study thus highlights where the habitats used by green turtles during the inter-nesting season are and how they are used. Therefore, management strategies and conservation decisions can be informed to maintain the viability of these essential habitats.