New Blue Whale Subspecies Discovered

Blue whales are the largest animals that have ever lived on our planet, and they are found around the globe in all oceans. All blue whales sing very low-pitched and recognizable songs, and conveniently for researchers, every population has its own unique song. In a recent study, the researchers describe a new blue whale song that is heard from the Arabian Sea coast of Oman across to the Chagos Archipelago in the central Indian Ocean and as far south as Madagascar in the southwest Indian Ocean.  While analyzing the Oman acoustic data, the team recognized the same unusual song. This novel blue whale song was recorded even more prevalently off Oman than Madagascar, and it became clear to the researchers that they had found what was likely a previously unrecognized population of blue whales in the western Indian Ocean.

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Backstory

Blue whales were hunted to near extinction around the globe during the 20th century, and populations have only started to recover very slowly over the past several decades following the global moratorium on commercial whaling. The Arabian Sea was targeted by illegal Soviet whaling in the 1960’s, an activity that nearly eradicated what were already likely to be small populations of humpback whales, blue whales, sperm whales, and Bryde’s whales.

Some researchers consider both the northern Indian Ocean blue whales and Arabian Sea humpback whales to comprise unique subspecies, not simply populations, making them particularly special and important to biodiversity.

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“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. Now, we are just beginning to learn more about another equally special, and likely equally endangered, population of blue whale.”

-Suaad Al Harthi, Executive Director of the Environment Society of Oman

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Journal Reference:  S Cerchio, A Willson, EC Leroy, C Muirhead, S Al Harthi, R Baldwin, D Cholewiak, T Collins, G Minton, T Rasoloarijao, TL Rogers, M Sarrouf Willson. A new blue whale song-type described for the Arabian Sea and Western Indian Ocean. Endangered Species Research, 2020; 43: 495.

Synopsis/   DOI: 10.3354/esr01096