Researchers spot humpback whales off Australia and Brazil — longest lifetime journey on record
Researchers have observed two humpback whales swimming between Australia and Brazil. It's the longest travel distance humans have ever recorded for the species. Two humpback
Researchers have observed two humpback whales swimming between Australia and Brazil. It's the longest travel distance humans have ever recorded for the species. Two humpback whales have been sighted in separate breeding grounds off Australia and Brazil, the first time scientists have seen the species travel such vast distances across the Southern Ocean during their lifetimes. An article published in the Royal Society Open Science journal on Wednesday is the upshot of using tens of thousands of images of the sea-dwelling mammals' unique tails (or flukes) to identify the creatures and their movement habits. Somewhat like human fingerprints, the markings on humpback whales' flukes or tails are unique, making it possible to identify individuals from photo records Image: Joseph Prezioso/Anadolu/picture alliance Where were the two whales seen, and when? One whale was spotted in Queensland, off Australia's eastern coast, in 2007 and then again in 2013. It subsequently appeared near Sao Paulo, Brazil, in 2019 — two points separated by roughly 14,200 kilometers (8,823 miles).
The other whale was first observed off the coast of Bahia in Brazil in 2003, and then 22 years later off Hervey Bay in Queensland, 15,100 kilometers away. The study said that it was not possible to record how much distance the whales had actually covered on their journeys, because their figures "reflect the separation between sighting locations rather than actual distances traveled, as photo-identification records only the endpoints of each individual's travel." Climate change's effects on ocean sea ice and prey locations could be altering or influencing whales' movement patterns Image: Joseph Prezioso/Anadolu/picture alliance The researchers said that the findings extended the known spatial limits of inter-basin connectivity for southern hemisphere humpbacks, supporting the "Southern Ocean Exchange hypothesis" — that the species could meet on shared Antarctic feeding grounds and then in exceptional cases follow a different route back to a breeding ground. The whales feed on krill and small fish in colder waters during the warmer summer months, and then move to more clement tropical waters — like those off Brazil and Australia — to breed during the winters.
"Resighting intervals of 6 and 22 years suggest that these are rare, possibly single-lifetime events rather than regular migratory shifts," the authors wrote. Whale 'Timmy' found dead near Danish island To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Preliminary data suggests such journeys are very rare Of the thousands of identified whales studied, only 0.01% of the sample was found to have completed such a journey. But researchers called for continued global collaboration on photo-ID platforms to try to get a better sense of how common it might be. "Despite their rarity, these exchanges matter for the long-term health of whale populations," Griffith University PhD researcher and report co-author Stephanie Stack said. "Occasional individuals moving between distant breeding grounds can help maintain genetic diversity across populations," she said, adding that they also might bring new songs to new pods in the process. Scientists suspect that climate change and warming oceans could make this phenomenon more common.
The BriefWire