[Above photo: An Arabian Sea humpback whale breaches following interaction with another whale. Both whales had just been recorded singing before this shot. Along with the genetic evidence presented in this study, the unique structure of humpback whale song recorded in the Arabian Sea indicates that this population is isolated and distinct from other whale populations in the Indian Ocean. Hallaniyat Bay, Dhofar, Oman. Photo credit: ©️Darryl MacDonald.]
 

Muscat, Sultanate Of Oman & Bronx, NY (September 28, 2026)—New genetic research has provided compelling evidence that the Arabian Sea humpback whale represents a distinct evolutionary lineage, supporting its potential recognition as a fourth subspecies of humpback whale. Published in Frontiers in Marine Science, the study marks a significant milestone in more than 25 years of whale research in Oman.

Led by the Wildlife Conservation Society in close collaboration with the Environment Society of Oman (ESO),  the Environment Authority of Oman, and other key local and international partners, the study compared genetic samples from Arabian Sea humpback whales with populations from across the world’s oceans. Researchers analyzed mitochondrial DNA from 2,285 humpback whales sampled across the species’ relevant and global range.

Results revealed high levels of genetic differentiation between the Arabian Sea population and the three currently recognized humpback whale subspecies of the North Atlantic, North Pacific, and Southern Hemisphere, indicating very limited gene flow between them. The Arabian Sea population also showed the lowest genetic diversity among the ocean regions examined. The findings support potential recognition of the Arabian Sea population as Megaptera novaeangliae indica. (Formal recognition of a marine mammal sub-species rests with The Society for Marine Mammalogy’s Taxonomy Committee.)

Lead author Dr. Rita Amaral, who coordinated the genetic analysis working with WCS, said, “Arabian Sea humpback whales have long been an enigma to the scientific community. Their ecology is unlike that of any other known humpback whale population, and this new genetic work represents an important milestone in understanding how that uniqueness developed. The results clearly indicate the Arabian humpback whales have followed their own evolutionary trajectory for tens of thousands of years and support their recognition as a distinct subspecies.”

The findings add to earlier evidence that Arabian Sea humpback whales are unique among studied humpback whale populations. Unlike other populations, they do not make long seasonal migrations between high-latitude feeding grounds and tropical breeding grounds. Instead, they remain year-round in tropical and subtropical waters, follow a Northern Hemisphere breeding cycle, and have a distinct song that is only heard in the Arabian Sea.

The genetic analyses estimated that Arabian Sea whale lineages diverged tens of thousands of years ago, with different groups showing estimated divergence times ranging from about 43,000 to 113,000 years ago.

Researchers also analyzed ancient DNA from the type specimen described as Megaptera indica in 1883—a whale collected near Basra, Iraq, remnants of which are held by the Muséum National d’Histoire naturelle in Paris. Morphological and genetic analyses confirmed that the specimen was a humpback whale and that it was closely related to contemporary Arabian Sea humpback whales. The findings support the proposed subspecies name Megaptera novaeangliae indica. (Formal recognition of a marine mammal sub-species rests with The Society for Marine Mammalogy’s Taxonomy Committee.)

Suaad Al Harthi, Executive Director of the Environment Society of Oman and a co-author of the study, said: “These findings are built on more than 25 years of dedicated research in Oman. What began with small-boat surveys to photograph individual whales and collect tiny tissue samples has developed into a much broader programme using satellite tracking, acoustic monitoring, health assessments, and other techniques. It is enormously rewarding to see samples collected during those early years now contributing to findings of such international scientific importance.”

The study emphasizes that the population’s isolation also makes it especially vulnerable. Arabian Sea humpback whales face threats from entanglement in fishing gear, vessel strikes, underwater noise, and pollution, as well as natural stressors such as disease. Climate-driven changes to monsoons and ocean upwelling may also affect the availability of sardines and other prey. The paper notes that the population is small, with no evidence of an increase over the past two decades, and warns that they are at risk of extirpation without concerted efforts to manage known threats.

Added Aida Al Jabri from the Environment Authority of Oman, “The growing body of research on Arabian Sea humpback whales has given Oman an increasingly clear understanding of both the importance of this population and the pressures it faces. This evidence is now helping us move from scientific understanding towards practical conservation action, including regional cooperation through the International Whaling Commission and Oman’s work to explore greater protection for important marine habitats through international mechanisms such as the International Maritime Organisation’s special protection provided by Particularly Sensitive Sea Areas.”

The International Whaling Commission recognizes Arabian Sea humpback whales as a discrete breeding and feeding population and has recommended implementation of a Conservation Management Plan. The study concludes that regionally coordinated conservation action and dedicated resources are urgently needed to protect the population and mitigate major threats.

As the only known humpback whale population in which the entire population both feeds and breeds in the same geographic area, Arabian Sea humpback whales are genetically, demographically, ecologically, and culturally unique. Given their status as an Endangered species, the study warns that their disappearance would mean the irreversible loss of a distinctive set of traits that can provide insight into how baleen whale populations adapt to environmental change.

Through its New York Bight Ocean Giants team, the Wildlife Conservation Society has made extensive contributions to our understanding of population differences and genetic structure for whales and dolphins all around the world. Said Dr. Howard C. Rosenbaum, Executive Director of the WCS New York Bight Program, “Our collaborative efforts through the years, and especially with this most recent publication, further highlights how Arabian Sea humpback whales are genetically distinct from other humpback whales around the world. Generating the robust science about its unique evolutionary history, isolated nature, and small population size strengthens the case for protecting these humpback whales throughout their range.”

The work to carry out the analyses in the paper was funded by the International Whaling Commission, and the sampling of the Paris Museum sample was funded by the US Marine Mammal Commission and facilitated by the MNHN Mammalogy Department.

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Environment Society of Oman (ESO)
The Environment Society of Oman is a membership-based environmental charity founded in March 2004. The Society is the first of its kind in Oman and works by promoting conservation and environmental awareness in all sectors of society. ESO is a member of the International Union for the Conservation of Nature (IUCN) and is part of UNEP’s Major Groups and Stakeholders (MGS) for West Asia. ESO’s vision is to play a leading role in the conservation of Oman’s natural heritage, and its mission is to protect and conserve Oman’s natural environment and influence environmentally sustainable behaviour through education, awareness and conservation. Its 2025 Annual Report can be accessed here. 
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