Monitoring genetic diversity of yellowfin tuna (Thunnus albacares Bonnaterre, 1788) from the eastern waters of Indonesia and other countries

The Pacific and Indian Oceans account for approximately 50% and 30%, respectively, of the world's total yellowfin tuna ( Thunnus albacares ) catch. Indonesia, a nation bordered by the Pacific and Indian Oceans, urgently needs to monitor the genetic variability of its economically significant fish species to provide a foundation for policymakers in sustainable fisheries management. Therefore, in this study, we aimed to identify tuna species in the Ombai Strait and investigated the genetic population structure of yellowfin tuna across six Indo-Pacific localities: Ombai Strait, Ambon, North Maluku, Okinawa, Philippines 1, and Philippines 2. The results revealed that all primary samples from the Ombai Strait were identified as Thunnus albacares and no significant differentiation was detected among the eastern Indonesian populations (Ombai, Ambon, North Maluku) or among the western Pacific populations (Okinawa and Philippines), suggesting a high degree of connectivity within these regions. Conversely, significant differentiation was observed between the Indonesian and western Pacific populations (FST = 0.079–0.121, p < 0.05). These findings provide preliminary genetic evidence for partially differentiated regional groupings of T. albacares within the study area. Despite the species' extensive migratory behavior, reproductive connectivity may be regionally constrained. Together, these results provide preliminary mtDNA-based evidence of regional genetic differentiation, but further analyses using nuclear or genome-wide markers are required before management implications can be assessed.