Warm season escape to deep: habitat range and seasonal movement of sand tiger shark Carcharias taurus in Ogasawara Archipelago, Japan

Temperature-dependent seasonal migrations are well-known in the sand tiger shark Carcharias taurus in Australia and the USA; however, its behavioral ecology in Japan remains unclear due to limited data. To investigate its habitat use and seasonal movements, we conducted acoustic tracking (n = 5) and archival tagging (n = 3) of individuals around the Chichijima Islands in the Ogasawara Archipelago, Japan. Three acoustic receivers deployed in different coastal areas recorded over 120 d of detections for all sharks, with 3 individuals exceeding 260 d. Average (±SD) acoustic detections were significantly higher in the cool season (275 ± 260) than in the warm season (54 ± 143). Additionally, archival tag data showed that sharks occupied deeper waters during the warm season (78 ± 42 m) than the cool season (24 ± 19 m). The combination of continuous acoustic detections in the cool season and the deepest dives of up to 206 m during the warm season indicates year-round residency of sand tiger sharks in the Ogasawara Archipelago, which is characterized by a continental shelf ranging from 30 to 200 m in depth. Unlike populations in other regions that migrate horizontally over more than 1000 km to maintain suitable temperatures, the Ogasawara population adjusts vertically, exploiting temperature stratification in the water column without extensive horizontal movement. Furthermore, repeated surfacing behaviors from depths greater than 100 m were observed. This study reveals an alternative migratory strategy adapted to the insular and oceanic conditions of the Ogasawara Archipelago.