The whale traveled more than 8,000 miles, the longest recorded migration for its species.
The world is changing, and the oceans are changing with it. For some species, these changes are troubling. Finding food or a mate is becoming increasingly difficult. While the ocean’s vastness can benefit species adept at navigating it, these challenges often outweigh the advantages.
Across three oceans. Marine biologists have documented an extreme case of marine migration: a humpback whale (Megaptera novaeangliae) sighted at distant points across three oceans. The whale was first observed in the western Pacific and later in the Indian Ocean near Africa’s coast.
From Colombia to Tanzania. The whale was initially sighted off Colombia’s Pacific coast in 2013, and it was seen there again in August 2017. Five years later, in August 2022, the same whale was spotted near the Zanzibar archipelago in Tanzania.
While previous records of humpback whale migrations spanned around 5,000 miles, this individual’s journey covered at least 8,000 miles.
The exact route taken by the whale over five years remains unknown. One possibility is that it traveled south through the western Pacific, crossed part of the Antarctic Ocean—home to critical feeding areas—and then traversed the Indian Ocean.
An unusual journey. Humpback whales commonly migrate. In the Southern Hemisphere, they move between feeding areas in high-latitude oceans, such as the Antarctic and parts of the western Pacific, Atlantic, and eastern Indian Oceans, and breeding grounds in tropical waters.
Known breeding areas include regions off Colombia, Brazil, the Gulf of Guinea, and Africa’s west coast, including Madagascar. Notably, one population of humpbacks migrates between two of the most distant breeding areas.
How are whales identified? Whales can be identified through various methods. DNA tests are one option, but collecting samples is often impractical. Researchers also use vocalizations, identifying whales by the unique sounds they produce.
For this particular whale, researchers relied on photographs. They matched images of the whale’s tail, focusing on its unique color patterns, using the platform Happywhale.com, which employs AI algorithms to assist in identification.
Details of the study have been published in the journal Royal Society Open Science.
A sobering record. The researchers behind the study have expressed concern over the whale’s extraordinary journey. While the exact reasons for this record-breaking migration remain unclear, they’ve proposed two main hypotheses: food scarcity and mating challenges.
The first hypothesis suggests that climate change may have reduced the availability of krill, tiny crustaceans essential to humpback whales’ diets. This scarcity might force whales to travel farther to find food, potentially altering their breeding grounds.
The second hypothesis, which could complement the first, points to the reduced whale population due to overfishing and other human activities. With fewer potential mates, whales may have to travel greater distances to reproduce. The phrase “there are plenty of fish in the sea” might not apply so easily to marine mammals anymore.
Image | Mike Doherty (Unsplash)
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