New Population of Blue Whales Discovered in the Western Indian Ocean
December 21, 2020
An international team of researchers has discovered what it believes to be a new population of blue whales in the western Indian Ocean. 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.
Dr. Salvatore Cerchio, Director of the African Aquatic Conservation Fund's Cetacean Program and Visiting Scientist at the New England Aquarium, first recorded the novel song in 2017, during research focused on Omura's whales in the Mozambique Channel off Madagascar, and he recognized it as a blue whale song that had never been described. Cerchio was also working with a team of scientists collecting acoustic recordings off the coast of Oman in the Arabian Sea. This is part of a research effort focused on the highly endangered Arabian Sea humpback whale, an ongoing collaboration between the Environment Society of Oman, Five Oceans Environmental Services LLC, Oman's Environment Authority, and Oman's Ministry of Agriculture, Fisheries and Water Resources. While analyzing the Oman acoustic data, the team recognized the same unusual song.
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 1960s, an activity that nearly eradicated what was 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.
Blue whales are threatened by a dozen factors, both natural factors and human activities. For instance, ship strikes have contributed to a significant decrease in the population of blue whales. Commercial fishing is also another threat to blue whales. The ocean is polluted with plastic and microplastic, which also suggests making blue whales susceptible. Other factors include climate change, ocean noise, oil leaks from industries, disease, toxins, bycatch, etc.
In the United States, blue whales are recognized as “endangered” under the Endangered Species Act and “depleted” and “strategic” under the Marine Mammal Protection Act. Whales are protected by the International Convention for the Regulation of Whaling on the international level, although a few countries are non-parties or withdrew from the convention. According to the International Union for Conservation of Nature, blue whales are listed under the category of Endangered. CITES and CMS Conventions list a blue whale in their Appendices I, which provides the strongest protection with regard to trade and use.