For the first time ever, scientists have spotted an individual humpback whale in both Brazil and Australia. To get from one breeding ground to the other, it swam for more than 15,000km (9,300 miles): a new record.
There’s a simple way to identify a humpback whale: by taking a photo of its tail fluke.
“The underside of a humpback whales’ tail has a unique black and white pigment pattern that doesn’t change (much) over the lifetime of that whale, akin to a human fingerprint,” says Stephanie Stack, a humpback whale researcher at Griffith University in Australia.
That means it can be used to tell one whale from another, along with the shape of the tail and other unique markings or scars. By uploading their fluke pics to a global database called Happywhale, scientists and tourists can help whale researchers study populations and learn more about where individuals go.
When researchers looked through 40 years of photographs (taken between 1984 and 2025) from eastern Australia and Latin America, they had a huge shock.
Among the 19,283 pictures they’d trawled through, something remarkable jumped out at them. Two of the whales were pictured in both Australia and the Americas.
“I had to check the photos multiple times for myself to believe it was true,” says Stack. “We know that humpback whales are capable of remarkable long-distance migrations, but finding photo-ID matches at this scale was something I never could have imagined.”
As impossible as it seemed, it was true. Both whales had crossed two oceans to move to another breeding ground on the other side of the world.
One whale was seen in Hervey Bay, Queensland, in 2007 and 2013 then popped up off the coast of São Paulo, Brazil in 2019 – roughly 14,200km (around 8,820 miles) as the crow flies (or, should we say, as the whale swims?).
The second whale was seen with a group of adults in humpback nursery grounds at Abrolhos Bank, Brazil, in 2003. More than 20 years later – in 2025 – photos showed it swimming alone in Australia’s Hervey Bay, around 15,100 km (more than 9,300 miles) away. The findings are published in the journal Royal Society Open Science.
Both whales break the previous record of the longest distance between sightings of an individual humpback. This was held by a whale that travelled 13,046km (more than 8,100 miles) from Chocó, Colombia – where it was seen in 2013 – to Zanzibar, Tanzania, where it appeared in 2022.
The new discovery is making scientists think twice. “Humpback whales are generally very loyal to their breeding grounds and return to the same region year after year,” explains Stack. “Finding not one but two individuals that have crossed between Australia and Brazil challenges what we thought we knew about how separate these populations really are.”
It’s incredibly rare for whales to move to a population on the other side of the world. According to the paper, “such events occurred in only 0.01 percent of identified whales.”
The few that do could help keep populations healthy by mixing up the gene pool. “Even rare crossings like these can help maintain genetic diversity and may help explain how humpback whale song spreads across ocean basins,” says Stack.
The researchers say the findings back up a theory called the Southern Ocean Exchange. “The Southern Ocean Hypothesis is the idea that humpback whales from different breeding populations all converge on the same Antarctic feeding grounds each summer,” explains Stack. “Occasionally an individual whale follows a different route rather than returning to where it came from.”
Anyone currently dipping their toe into the dating pool might understand this desire to see what prospective partners are like outside your hometown.
The experts stress that this amazing discovery wouldn’t have been possible without the collaboration of people all around the world – even people outside of the scientific community who wanted to help research efforts by sharing their photos with Happywhale.
“This kind of research highlights the value of citizen science,” says Cristina Castro, Pacific Whale Foundation, in a statement. “Every photo contributes to our understanding of whale biology and, in this case, helped uncover one of the most extreme movements ever recorded.”
Top image credit: Pacific Whale Foundation
