A transnational citizen science database has documented two humpback whales traveling unprecedented distances between Australia and Brazil, directly challenging the long-held understanding that distinct humpback whale populations remain separate within their breeding grounds.
One whale was photographed in Hervey Bay on the Fraser Coast in 2013 before being photographed off the coast of São Paulo, Brazil, in 2019, covering a straight-line ocean distance of 14,200 kilometers. This journey was identified after 13 years and 7 years respectively since the initial sighting.
A second whale was first photographed in 2003 at the Abrolhos Bank, Brazil's main humpback whale nursery off the coast of Bahia, among a large group of nine adults. In September 2025, 23 years later, it was spotted alone in Hervey Bay, Australia, a travel distance of 15,100 kilometers, marking the longest distance ever documented between sightings of an individual whale.
The findings, published by Royal Society Open Science, were made possible by analyzing 20,000 photographs of whales across the Southern Hemisphere, collected since the 1980s, using the citizen science platform Happywhale. This global platform utilizes unique fluke markings, akin to human fingerprints, for individual identification.
Challenging Established Boundaries
Griffith University PhD candidate Stephanie Stack, a co-author of the paper, stated that it was generally understood that humpback whales would stay in distinct breeding ground populations. Ms. Stack confirmed that there had never been any photographic evidence linking these two populations before this study.
Ms. Stack further indicated that traveling to other whale populations would contribute to genetic diversity as the animals recover from the impacts of whaling. She also described this movement as part of cultural transmission, explaining how whales pass behaviors and knowledge to one another. Ms. Stack noted that humpback whales are known to spread song from one population to another across the hemisphere, suggesting other lines of evidence for mixing and movement, though never before seen with photographic identification.
Marine Scientist Wally Franklin of the Oceania Project described the finding as both surprising and extraordinary. Dr. Franklin highlighted that humpback whales from various regions, including east and west Africa, east and west Australia, and east and west Brazil, all migrate to the South Pole. He noted that the degree to which these whales are mixing down there has been an open question for some time.
The Globalist Mechanism
The study underscores the increasing reliance on transnational data collection and global collaboration. Ms. Stack explained that the opportunity for scientists to access photographic data submitted to these citizen science platforms is significant. She emphasized that using photographs, collated since the 1970s, represents a non-invasive way to learn about whale lives.
Ms. Stack detailed the global platform's functionality, stating that anyone who photographs a whale tail anywhere in the world can upload their image for comparison. She added that many researchers also contribute their catalogues to this unified system. Acknowledging the role of citizen scientists, Ms. Stack confirmed that a couple of the photographs used to identify the two traveling whales were taken by individuals participating in the platform.
Ms. Stack concluded that with this new methodology of global collaboration, researchers are uncovering many new things about whales previously unknown. While the start and end points of these journeys have been recorded, Ms. Stack stated that the whales' exact routes or their current status remain a complete mystery, indicating that much about humpback whales still needs to be uncovered.