Transoceanic migration of a female tiger shark (Galeocerdo cuvier) demonstrates connectivity in the southern Atlantic

The tiger shark is a highly migratory apex predator with distinct populations in the Atlantic and Indo-Pacific regions. Regional analyses in the western Atlantic Ocean have revealed additional genetic differentiation between northern (Caribbean) and southern (Brazilian) populations, particularly in maternally inherited mitochondrial DNA. The eastern Atlantic Ocean, however, remains understudied, leaving connectivity between American and African populations unresolved. Using a fin-mounted satellite transmitter, we document the complete eastward transatlantic movement of a female tiger shark (2.9 m total length), tracked from Fernando de Noronha Archipelago, Brazil, to the coastal waters of Sierra Leone, West Africa. Following an initial prolonged residency of around Fernando de Noronha, the individual undertook a 6,764 km migration across the Atlantic over 116 days (mean ~58 km day -1 ). Surfacing behavior differed significantly between the residency and migration phases, shifting from predominantly nocturnal to predominantly diurnal detections. This movement corroborates previous findings that female tiger sharks can disperse across basin scales and suggests that equatorial migration may facilitate genetic connectivity between the western and eastern Atlantic. In the absence of genetic data from West Africa, the demographic and genetic consequences of such movements remain undetermined, underscoring the need to integrate telemetry with expanded population genetic sampling to better understand connectivity in highly mobile marine predators.