The Mediterranean spearfish (Tetrapturus belone) is a highly migratory predator, exploited by commercial and recreational fisheries. Fragmentary catch, landing and poorly reported data, are the main reasons of the unknown fishing pressure on this species. Further ecological information, including migratory movement, is also needed before management measures can be set, and the population status still awaits examination by ICCAT. Indeed, species' migratory behaviour is crucial for addressing conservation challenges and supporting management decisions. In this study, we investigated the migratory movements, seasonal patterns, vertical behaviour, and thermal preference of T. belone, to improve information on its ecology and behaviour.
Overall, six pop-up satellite tags were deployed in the Strait of Messina and Tyrrhenian Sea and the animal movements were mainly restricted to the central Mediterranean. Spatial analysis using geolocation data revealed that the Tyrrhenian Sea and Strait of Sicily are key habitats for Mediterranean spearfish, both generally and seasonally, although winter habitat use showed variability. While the species primarily occupies the near-surface layer (≤ 10 m depth), occasional deep dives below 200 m were recorded. Consistent with other billfishes, T. belone exhibited a diel vertical migration pattern, utilizing shallower, warmer waters during the night and deeper, cooler waters during the day. This study provides valuable insights into the migration ecology and habitat preferences of T. belone, contributing essential information for the management of this relatively understudied species.