Genetic research has confirmed that the Arabian Sea humpback whale is a distinct subspecies, according to a study published in Frontiers in Marine Science. The findings, based on 25 years of research in Oman, reveal a population with unique culture, breeding patterns, and feeding routines.
Genetic evidence of a unique subspecies
The study compared genetic samples from Arabian Sea humpback whales with populations from across the world’s oceans, analyzing mitochondrial DNA from 2,285 humpback whales. Researchers found that the Arabian Sea population is genetically very different from North Atlantic, North Pacific, and Southern Hemisphere whales, and shows the lowest genetic diversity among the regions examined.
Lead author Dr. Rita Amaral 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.”
Unique behaviors and ancient lineage
The findings support potential recognition of the Arabian Sea population as Megaptera novaeangliae indica. Unlike other humpbacks, these whales do not make long seasonal migrations between feeding and breeding grounds. Instead, they stay in sub-tropical waters year-round, follow a Northern Hemisphere breeding cycle, and have a distinct song heard only in the Arabian Sea.
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 examined ancient DNA from the type specimen described as Megaptera indica in 1883—a whale collected near Basra, Iraq, held by the Muséum National d’Histoire naturelle in Paris—confirming it was closely related to contemporary Arabian Sea humpbacks.
Conservation urgency
The research was led by the Wildlife Conservation Society in collaboration with the Environment Society of Oman (ESO). Suaad Al Harthi, Executive Director of ESO and 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 population faces threats from entanglement in fishing gear, vessel strikes, underwater noise, and pollution, as well as natural stressors such as disease. Climate change also threatens the species, with monsoons and ocean upwelling affecting food availability like sardines. The small population is at risk of extinction without intervention.
Aida Al Jabri from the Environment Authority of Oman added: “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 distinct species and has recommended a Conservation Management Plan. The study states that coordinated conservation action and dedicated resources are urgently needed. As the only known humpback population where the entire group feeds and breeds in the same geographic area, their loss would mean the irreversible disappearance of a distinctive set of traits that could offer insight into how baleen whale populations adapt to environmental change.
Dr. Howard C. Rosenbaum, Executive Director of the WCS New York Bight Program, said: “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.”
