A humpback whale completed a migration of over 13,000 kilometers, while some southern right whales have a « natural » lifespan of over 130 years.
They had been relatively quiet in 2024. No major discoveries, no striking achievements to savor. A quiet season for the whales. But this plunge into anonymous waters was only a prelude to two spectacular leaps. On December 11, 2024, an international team announced in the journal Royal Society Open Science that a humpback whale had completed a migration of over 13,000 kilometers, smashing the previous record of 10,000 kilometers. On December 20, 2024, three ecologists estimated in Science Advances, supported by data, that extreme longevity in southern right whales was « the rule, not the exception, » with 10% of individuals surpassing 131 years. The figures are impressive, but with these sea giants, we are accustomed to it. Moreover, these records bring a new perspective on these iconic yet poorly understood animals.
Let’s consider the humpback whale. For centuries, scientists have observed its north-south migrations around the globe. For example, an individual may spend the winter in Colombia, reproduce there, and then head to Antarctica in the summer to gather krill. A journey of about 6,000 kilometers. The same occurs in the Northern Hemisphere between Hawaii and the Arctic Ocean. Well-marked routes. But could some individuals stray off course? In 2010, researchers identified a female off the coast of Madagascar who had been photographed two years earlier in Brazilian waters. The whale had gone south, then navigated eastward to cross the other side of Africa. A total of 10,000 kilometers.
This time, it was in the Zanzibar Channel that Ekaterina Kalashnikova (from the Tanzania Cetaceans Program, also the first author of the article in Royal Society Open Science) and her colleagues spotted a male already known to them. The animal had been observed twice before, in 2010 and 2013, off the coast of Colombia. Photos of its tail had been entered into the Happywhale.com database. The site, created 15 years ago, houses 900,000 photos of flukes taken by both amateurs and professionals. The cetacean equivalent of human fingerprints. The software did the work, revealing a new record: 13,046 kilometers. The whale had to travel the entire South American coast, cross Cape Horn, continue eastward, pass Cape of Good Hope, before turning north toward its new destination on the eastern coast of Africa.
« Behavioral plasticity »
Such a journey suggests that the animal had changed its « pod, » the social group that structures whale life and follows the same route each year. The reason? Possibly the search for a mate, the authors of the article suggest. However, « global climate change and an altered environment may also explain this unusual exploration of a new habitat, » they add. A variety of hypotheses that cetologist Fabienne Delfour, a researcher at ILCB, Aix-Marseille University, appreciates. « The study reveals the behavioral plasticity of these animals, » she adds, « and that’s good news considering the challenges ahead: climate change, pollution, maritime traffic… »
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The other performance set by the whales in 2024 is also based on image databases. Greg Breed (University of Alaska, USA) and his colleagues analyzed all the « recapture » data of right whales gathered over more than forty years. In other words, individuals that were seen again. They then used new demographic models that allow for better estimation of population structures. The result: southern right whales (Eubalaena australis) have a median lifespan of 74 years, with 10% of individuals exceeding 131 years.
A big surprise in the world of large cetaceans. Until now, the bowhead whale (Balaena mysticetus) had been seen as an exception, regularly exceeding 150 years. Even more surprising, North Atlantic right whales (Eubalaena glacialis) have a median lifespan of only 22 years, with only the 10% oldest individuals reaching 47 years. « Biologically, they are practically identical, » Greg Breed recalls. « The difference comes from human-induced mortality. » Collisions with ships, accidental entanglements in fishing nets: while whale populations have generally increased over the past 30 years, the North Atlantic right whale population has declined. There were 20,000 at the beginning of the 20th century, and only 373 remained in 2023. Another record, but a sad one.
