New whale group sings hello
A new population of blue whales has been found in the Indian Ocean after marine researchers stumbled upon their unique song.
Blue whales are the largest creatures ever to have lived, with hearts the size of cars and stomachs that can hold at least a tonne of krill.
Little is known about how the species is faring. The new group was found thanks to the whales’ low-pitched calls, which can travel underwater for nearly 1000 kilometres.
Only the males sing, but their drone is as loud as the noise made by a large ship. It is unclear if this extraordinary communication, at the farthest reach of human hearing, is intended to repel rivals, attract a mate or achieve something else.
Each region’s whales have a unique style, meaning that the discovery of a new song signalled the presence of an unknown cohort.
Its particular tune has been heard in the northernmost reaches of the Arabian Sea, as far south as the Chagos Islands and in the Mozambique Channel, west of Madagascar. It has been added to the list of a dozen or so blue whale songs.
Dr Salvatore Cerchio, a marine mammal biologist who works for the African Aquatic Conservation Fund, was the first scientist to hear it. His team was recording off Oman as part of research into the Arabian humpback whale.
‘‘It was quite remarkable to find a whale song in your data that was completely unique, never before reported, and to recognise it as a blue whale,’’ Cerchio said.
The team notified the Scientific Committee of the International Whaling Commission. Its report was read by researchers at the University of New South Wales, who realised that they had heard the same song off the Chagos Islands.
It had previously been assumed that the blue whales of the Arabian Sea belonged to a population that had been studied off Sri Lanka, but the music told a different story.
‘‘Before our recording off Oman, there were no acoustic data from the Arabian Sea, and so the identity of that population of blue whales was initially just a guess,’’ said Andrew Willson, a member of the research team. ‘‘Our work shows that there is a lot more to learn.’’
Blue whales were hunted to the brink of extinction in the early 1900s. Numbers have slowly increased after a global moratorium on commercial whaling.