A blue whale. Photo: Christopher Michel/Flickr, CC BY 2.0
New Delhi: Scientists have found evidence of a previously unknown population of blue whales living in the western Indian Ocean based on an analysis of sound recordings from the region, reported The New York Times.
According to a recently published study in the journal Endangered Species Research, this group of whales has its own distinct song, different from any other whale song. So far, only about a dozen blue whale songs – each of which is a distinct identifier of a unique population – have been documented. Several blue whale populations have previously been recognised based on their distinct songs.
Asha de Vos, a marine biologist, said that the discovery was “a great reminder that our oceans are still this very unexplored place”.
The scientists involved in the study first recorded the song while undertaking research focused on a pod of Omura’s whales off the coast of Madagascar. It soon became apparent to the researchers that they had found a previously unidentified population of blue whales.
“It was quite remarkable to find a whale song in your data that was completely unique, never before reported, and recognize it as a blue whale,” said Dr Salvatore Cerchio, who led the analysis of recordings of the whales. “With all that work on blue whale songs, to think there was a population out there that no one knew about until 2017, well, it kind of blows your mind,” Cerchio said.
Researchers said that they had initially assumed that the whales in question belonged to the same population of blue whales near Sri Lanka that had already been studied.
“Before our recording effort 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 study co-author Andrew Willson from Five Oceans Environmental Services LLC. “Our work shows that there is a lot more to learn about these animals, and this is an urgent requirement in light of the wide range of threats to large whales related to expanding maritime industries in the region.”
Hunted to near extinction, the number of blue whales shrank from 250,000 to around 1,000 by 1950s and started to recover from their dwindling numbers only recently following a global moratorium on commercial whaling.
“For 20 years we have focused work on the highly endangered Arabian Sea humpback whale, for which we believe only about 100 animals remain off the coast of Oman,” said Suaad Al Harthi of the Environment Society of Oman. “Now, we are just beginning to learn more about another equally special, and likely equally endangered, population of blue whale.”
Earlier this year, the outbreak of COVID-19 triggered an economic slowdown and reduced shipping traffic. Soon after scientists with the International Quiet Ocean Experiment put together an array of underwater hydrophone listening stations around the world which would give scientists recordings of a glimpse of the ocean with little human interference