Scientists have identified two humpback whales that made separate, record-breaking crossings between Australia and Brazil, covering distances of over 9,000 miles (14,500 kilometers). The whales were distinguished by their unique tail markings at both locations, traveling in opposite directions and surpassing any known humpback migration.
Rare and Remarkable Journeys
According to Phillip Clapham, former head of a NOAA whale research program who was not involved in the study, such events are extremely rare but demonstrate the remarkable range of these animals. Humpback whales are known for long migrations across oceans, typically following routes learned from their mothers. They feed on krill and small fish in warmer months and breed in tropical waters during winter.
Tracking these marine creatures is challenging due to their underwater lifestyle. In the new study, researchers analyzed over 19,000 whale images collected over four decades by research groups and citizen scientists. Recognition software identified whales based on tail color patterns and jagged edges. Two distinct whales were spotted at breeding sites in eastern Australia and Brazil over the years, indicating they had crossed from one region to the other. One whale traveled just over 9,300 miles (15,000 kilometers), breaking previous records, including a humpback that swam from Colombia to Zanzibar.
Implications for Whale Migration Knowledge
The findings, published in the journal Royal Society Open Science, do not reveal the exact routes taken since photos only capture the whales at the start and end of their journeys. Whales typically do not travel between mating sites, so it is unclear why these two embarked on their odysseys. They may have encountered other whales on shared feeding grounds and diverged instead of returning to their origin, suggested study co-author Stephanie Stack of the Pacific Whale Foundation.
Stack noted, "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." Such journeys are more difficult for whales in the Northern Hemisphere due to large continents. The record highlights the extensive range of humpback whales and the importance of tracking methods as climate change warms oceans, potentially altering krill habitats and whale feeding and breeding patterns.
