Migratory connectivity of pelagic predators between tropical Atlantic islands and seamounts revealed through passive acoustic telemetry

BACKGROUNDOceanic islands and seamounts are recognised as hotspots of abundance and diversity for marine top predators, such as sharks and large teleosts, and are hypothesised to function as migratory stepping stones for mobile, pelagic species. However, while movements of pelagic predators between such features have been documented in some oceans, evidence from the tropical Atlantic remains limited. RESULTSHere, we report on long-distance migrations of three species of pelagic predator between oceanic islands and seamounts in the tropical south Atlantic recorded via independent passive acoustic telemetry arrays. These include the first recorded trans-Atlantic migration of a Galapagos shark (Carcharhinus galapagensis) from Ascension Island (UK) to the Sao Pedro and Sao Paul Archipelago (Brazil) (minimum distance 1,930 km); the longest documented oceanic migration of an Almaco jack (Seriola rivoliana) from St Helena (UK) to Ascension Island (minimum 1,300 km); and multiple movements of Galapagos and silky sharks (C. falciformis) between two Mid-Atlantic Ridge seamounts and Ascension Island (minimum 265-325 km). These detections are notable given the limited duration, sample sizes, and temporal overlap of acoustic tracking studies in the region, suggesting substantial connectivity across large spatial scales. CONCLUSIONSOur findings provide empirical support for the role of oceanic islands and seamounts as connectivity hubs for pelagic predators in the tropical Atlantic, underscoring their importance as key nodes in marine protected area networks. More broadly, this study demonstrates the value of collaborative regional tracking networks in resolving large-scale movement patterns and informing marine management at ecologically relevant scales.