QUEENSLAND — A study published Wednesday in Royal Society Open Science documented two humpback whales that traveled between the eastern shores of Australia and breeding grounds in Brazil, covering distances of approximately 8,823 and 9,383 miles. The journeys are the greatest ever recorded for the species.

One whale was photographed in Queensland in 2007 and then near Sao Paulo, Brazil, in 2019, a distance of about 8,823 miles. Another was sighted off the coast of Bahia, Brazil, and 22 years later in Hervey Bay, Australia, about 9,383 miles away. The photographs represent the longest distance ever observed between two images of the same humpback whale.

Researchers analyzed nearly 20,000 photographs collected between 1984 and 2025 from eastern Australia and Latin America, contributed by scientists and citizen scientists. The images were run through an automated image-recognition algorithm to identify the two whales photographed in both regions.

The findings lent further credence to the "Southern Ocean Exchange" hypothesis, which proposes that humpback whales sometimes travel to Antarctic feeding grounds and then take a different journey home, ending up in a new breeding area. Such journeys occur rarely.

"Despite their rarity, these exchanges matter for the long-term health of whale populations," said Stephanie Stack, a PhD researcher. "Occasional individuals moving between distant breeding grounds can help maintain genetic diversity across populations."

Dr. Cristina Castro, a researcher involved in the work, pointed to the contributions of nonprofessional observers. "This kind of research highlights the value of citizen science," Castro said. "Every photo contributes to our understanding of whale biology and, in this case, helped uncover one of the most extreme movements ever recorded."

Environmental conditions may be a factor in the long crossings. "Climate-driven changes to the Southern Ocean, including shifts in sea ice and the distribution of Antarctic krill (the whale's main prey), may be making such crossings more likely over time," Griffith University said.

Humpback whales can grow up to 55 feet long. According to NOAA, commercial whaling led to humpback whales being listed as endangered in the United States in the 1970s, and a final moratorium on commercial whaling was established in 1985. Under U.S. law, four of the fourteen distinct humpback whale population segments are still listed as endangered and one is listed as threatened.