An individual humpback whale (Megaptera novaeangliae) can easily be recognized by its tail. The shape and pattern on its underside are as unique as a human fingerprint. It is also very fortunate that the whale often throws its tail into the air above water when it dives, an ideal moment for identification.
Whale researchers are gratefully using it to map the impressive migration patterns of these marine mammals. They mate in subtropical regions and then forage in the cooler icy seas around the poles. They travel up and down twice a year, over distances of thousands of kilometers. There are different populations, each with their own migration route.
For example, there is a population with a mating area along the coast of South America in the Atlantic Ocean (near São Paulo in Brazil) and a population with a mating area along the east coast of Australia in the Pacific Ocean (Hervey Bay, Queensland). In principle, these humpback whale populations never meet each other, but genetic research had already shown that there was sometimes an exchange.
A new study which used an archive of tail photographs of 19,283 individual humpback whales, taken between 1984 and 2025 in the breeding areas of both populations, has now ‘caught’ two adult humpback whales swimming from one population to the other.
One swam from Australia to Brazil, and the other made the reverse crossing. This means that these two animals must have swum record distances of at least 14,200 and 15,100 kilometers, the as the crow flies distance between the different photo locations. It is not possible to determine exactly which route the animals followed during their crossing, but the actual distance traveled is probably much greater. The gender of one whale is unknown, the second is probably a male, the researchers conclude from its behavior.
The time period within which the record swim must have taken place was six years for one whale and 22 years for the other. Combined with the rarity of these types of sightings, the researchers conclude that such a large crossing to another population in another ocean is likely a “once in a lifetime” event for a humpback whale.