Interbreeding area movement of an adult humpback whale between the East Pacific Ocean and Southwest Indian Ocean

Humpback whales undertake one of the longest known migrations of any mammal. While their migration route generally extends between latitudes, the breeding stocks are longitudinally separated and display high site fidelity to their feeding grounds. While there is an indication of certain breeding stocks overlapping with each other, the current information on the migration routes of humpback whales within the Southern Hemisphere limits our understanding on the extent of this exchange. Here, we present the longest documented great-circle distance between sightings on wintering grounds of two different Ocean basins of an adult male humpback whale between two breeding stocks in the eastern Pacific (stock G) and Southwest Indian Ocean (stock C). These two stocks were separated by a minimum of 120° longitude, and 13,046 km of a great-circle distance. These extreme distances movements demonstrate behavioural plasticity, which may play an important role in adaptation strategies to global environmental changes and might be an evolved response to various pressures and underline the importance of consolidation of the global datasets on wide ranging marine mammals.

Methods
The data have been collected on the dedicated vessel-based surveys in Colombia and Tanzania. Location, behaviour, group type, group size, spatial distribution, and photo-identification images were collected in all locations. Fluke images were uploaded to Happywhale.com a web-based cetacean photo-ID platform.