A multi-method approach across ocean basins challenges fin whale classic migratory assumptions off South America

Baleen whale classical pattern of summering in high latitude and wintering in low latitude has been framed within a continuum of migratory schemes. Here, we aim to understand fin whale distribution and migratory patterns off South America by summarizing dedicated visual surveys, passive acoustic monitoring, and telemetry data from Chile, Argentina, and Brazil. Our results agree with findings from other fin whale populations and whaling records from South America, supporting the existence of multiple migratory schemes including year-round residency and classic migration. An unprecedented case of a “seasonally inverted migration”, with an individual summering in low-mid latitudes and wintering in high latitudes is presented as the first description of a fin whale round trip migratory route in the Southern Hemisphere. Our results reinforce the notion that baleen whale migratory movements are more diverse than previously thought and highlight the relevance of international cooperation for the study and conservation of migratory species.