Habitat preferences of the sicklefin lemon shark (Negaprion acutidens) in the Dongsha Atoll National Park: a preliminary assessment

Habitat preferences of the sicklefin lemon shark (Negaprion acutidens) in the Dongsha Atoll National Park: a preliminary assessment

Collecting basic biological information of a species is crucial for developing effective conservation strategies and ensuring its sustainable management. Dongsha Atoll is considered a vital, possibly the primary, nursery ground for the endangered sicklefin lemon shark (Negaprion acutidens) in the South China Sea. In this study, we employed acoustic telemetry to investigate the habitat utilization and preferences of N. acutidens at different life stages in Dongsha Atoll. A total of 44 sharks, including 16 juveniles, 14 small sharks, 11 sub-adults, and three adults, were tagged and tracked for 1–848 days. Results of this preliminary assessment revealed that: (1) juvenile and small sharks commonly utilize the shallow seagrass flats around Dongsha Island, with juveniles spending a significant amount of time in the embedded lagoon; (2) sharks of all sizes utilize the lagoon mouth area, especially small and sub-adult sharks; (3) adult sharks exhibit a broader activity range within the atoll and are unlikely to enter the embedded lagoon. We hypothesize that the embedded shallow lagoon of Dongsha Island serves as a shelter area for newborns and juveniles, while the lagoon mouth may function as an important hunting ground for small and sub-adult sharks. Adult sharks may have the broadest home range around the atoll and close to Dongsha Island during the breeding season. This study underscores the importance of considering habitat shifts and changes in home range size throughout the ontogeny of N. acutidens when planning effective spatial management strategies.