An international team of researchers has discovered what it believes to be a new population of blue whales in the western Indian Ocean, including the Arabian Sea and the coast of Oman.

This came as part of a research effort initially focused on the highly endangered Arabian Sea humpback whale. Blue whales are the largest animals that have ever lived on the planet, and they are found around the globe in all oceans. All blue whales sing very low-pitched and recognisable songs, and conveniently for researchers, every population has its own unique song. 

In a recently published paper in the journal Endangered Species Research, 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.

The research was conducted with ongoing collaboration between the Environment Society of Oman, New England Aquarium, African Aquatic Conservation Fund, Five Oceans Environmental Services LLC, Oman’s Environment Authority and Oman’s Ministry of Agriculture, Fisheries and Water Resources. The work was funded by Shell Development Oman (SDO), with support from the International Whaling Commission, Renaissance Services, and NOAA Fisheries.

Dr Salvatore Cerchio, director of the African Aquatic Conservation Fund’s Cetacean Programme, and visiting scientist at the New England Aquarium, led the analysis of recordings of the whale from three locations in the western Indian Ocean. 

Dr Cerchio first recorded the novel song in 2017, during research focused on Omura’s whales in the Mozambique Channel off Madagascar, and he recognised it as a blue whale song that had never been described while working with a team of scientists collecting acoustic recordings off the coast of Oman in the Arabian Sea. While analysing the Oman acoustic data, the team recognised the same unusual song. This novel blue whale song likely belonged to a previously unrecognised population of blue whales in the western Indian Ocean. 

“It was quite remarkable,” said Dr Cerchio, “to find a whale song in your data that was completely unique, never before reported, and recognise it as a blue whale.” 

Blue whale songs have been extensively studied globally, and several blue whale populations have been identified based on their distinct songs throughout the Indian Ocean. 

In 2018, the research team reported their findings to the Scientific Committee of the International Whaling Commission (IWC), which was in the process of evaluating the status of blue whale populations in the Indian Ocean. The finding created quite a bit of excitement at the meeting, and raised many new questions about blue whale population movements and structure in the Indian Ocean. 

Dr Thuraya al Sariri, deputy director general of Nature Conservation, Oman’s Environment Authority, said, “The finding of blue whales across Oman’s coast is quite extraordinary. We look forward to continue collaborating with all partners to boost research showing evidence on how these endangered species can be conserved in the Arabian Sea.”