New groundbreaking findings in research led by BCSS’s very own Ekaterina Kalashnikova reveal extraordinary humpback whale (Megaptera novaeangliae) migratory behavior and have made major news coverage in international journalistic outlets, including the BBC, the Guardian, CBC, the Independent, and NBC, as well as science news platforms, journals, and magazines.
The study, published in Royal Society Open Science, documents the longest recorded migration of a humpback whale between breeding grounds in two distinct ocean basins. The adult male whale undertook an extraordinary journey of at least 13,046 kilometers, potentially covering up to 18,000 kilometers, connecting populations in the East Pacific and the Southwest Indian Ocean, making this the longest recorded great circle distance between breeding grounds for a humpback whale. Underscoring the scientific mystery surrounding the motivations behind interoceanic journeys of humpback whales, the study serves as a testament to the need for additional transboundary research.
Researchers were able to determine that the journey began in the Gulf of Tribugá, Colombia, where the whale was first observed in a “competitive group” of seven individuals, accompanied by bottlenose dolphins. Competitive groups describe whale group structure in which typically a female is closely guarded by an adult male, while several additional males follow the pair competing for the right to mate with the female. Subsequent sightings in 2017 in Bahía Solano, Colombia, and 2022 in Zanzibar confirmed its identity through detailed photographic analysis using AI algorithms of the Happywhale platform, which employs automated image recognition to track cetaceans globally.
“Individual photo-identification of whales allows researchers to link sightings split by years and thousands of kilometers, providing opportunity for assessment of movement patterns, sub population structure, estimate abundance, site fidelity and residency time,” Kalashnikova said. “Nonetheless, calculating the actual distance traveled by an individual whale is challenging, as exact migratory routes are speculative. To estimate the scale of this migration, we used great circle distances between sightings, which describes the distances between points on a sphere, measured along the great circle arc between them. While the precise route of this whale remains unknown we calculated one-way distances for key legs of the journey. This calculation brought the minimum cumulative distance traveled by the whale to 18,397–19,107 km, though the actual distance was likely even greater. Such an extensive journey is unusual.”
Humpback whale match on Happywhale. (Ekaterina Kalashnikova/BCSS)
This whale’s consistent association with competitive groups across its travels and photographic evidence of a genital slit suggest it is a mature male. The implications of its long-distance migration are profound, albeit unclear.
Humpback whales are renowned for their incredible migrations, often demonstrating strong loyalty to specific feeding and breeding areas. However, this individual defied expectations, providing new insight into the flexibility of their movements. Potential drivers of such movements could include environmental changes, mating strategies, or increased competition in traditional breeding grounds.
“Food availability on these feeding grounds is determined by many factors, one of which is coverage of sea ice which will directly impact the abundance of Antarctic krill in the case of southern hemisphere humpbacks. Reduction of sea ice coverage of approximately 30 percent over the past 40 years due to warming oceans will have an impact on krill reproduction and thus also affect humpback (and other) whales. An area that has previously been a good source of food for humpbacks might no longer sustain their needs which will inevitably lead to them seeking out other areas to forage which consequently can lead to an extension of their migratory track and possibly a different breeding ground after the feeding season,” said Happywhale’s Alex Vogel, a co-author of the study.
It is uncertain if a humpback whale that has moved out of its native feeding area is more prone to change its wintering destination.
“But it makes sense that as winter approaches, due to time restraints and given the high energetic cost of returning to its previous migratory path, such an individual could choose to travel to a different breeding destination. This energetic cost would be even more relevant under the influence of the Antarctic Circumpolar Current (ACC), which would favour eastern movements and raise the energetic cost of westward movements given its eastward flow in the bottom of the planet,” said Jardín Botánico del Pacífico Mecana’s Esteban Duque Mesa who also co-authored the study.
More global and transboundary reseach is necessary to confirm any potential scientific assumptions about the reasons for this humpback whale’s particularly long migratory journey. Long-term monitoring and genetic studies will be crucial in unraveling the complexities of these wide-ranging marine mammals and their responses to a changing world.
Meanwhile, DMAD’s main Tanzanian research supervisor and one of the leading authors of this study, Dr. Aylin Akkaya is fascinated by the way this whale is “mixing the culture,” as she describes:
“Different populations of humpbacks have their own unique whale songs and dialects, which vary between regions. So, in Colombia, they speak more Latino. And in Tanzania, they have … fragments of African languages. What we are curious about now, this male, does it [have] a Colombian song or does it [have] an African song?”
The Zanzibar sighting also reinforces the Western Indian Ocean (WIO) region’s critical role in connecting breeding populations across the region and beyond. This highlights the importance of global photo-ID databases and collaborative, long-term monitoring efforts in advancing our understanding of humpback whale behavior and migration ecology.
“Publications such as this one are proof that data sharing and collaboration are the way forward,” said Alex Vogel.
Study lead-author Ekaterina Kalashnikova agrees.
“Most inspiring about this match is that it brought together scientists from Tanzania, Russia, Colombia, the U.S., Turkey, South Africa, and Ireland, facilitating new collaboration opportunities and uniting researchers allowing to join forces in unlocking new knowledge by working together.”
Situated in Mozambique’s Bazaruto Archipelago along the humpback whales’ migration route, BCSS is uniquely positioned to contribute to this important collaborative work. From July to October, humpback whales pass through these waters, making BCSS an ideal base for further research into their behaviors, migration patterns, and ecological roles.
If you are a student or early career scientist interested in marine mammal research and would like to work alongside Ekaterina Kalashnikova researching humback whale bahavior, contact us to apply for our 2025 Scientific Training Program. Katya will be collecting data in Mozambique in September and October.
The authors would like to express gratitude and cordial appreciation to everyone who contributed to this research, but especially to the Government of Tanzania and Zanzibar, to DMAD for the tremendous effort setting the research off the ground and overall supervision, Alexander Vogel who’s been instrumental in the photo ID component of the study, and Dr Tim Davenport of Re:Wild for over a decade of inspiration and support.
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For questions about this article, please contact:
Ekaterina Kalashnikova, Bazaruto Archipelago – Ocean Observatory Bazaruto Center for Scientific Studies ekaterina.kalashnikova@bcssmz.org
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