Due to its shallow nature, most native small cetaceans in the Persian Gulf are nearshore species. There are three species of nearshore cetaceans distributed through the area:
- Indo-Pacific bottlenose dolphin (Tursiops aduncus): these dolphins are known as one of the most numerous small cetaceans inside the Gulf. The species is widespread along the Strait of Hormuz at the entrance of the Persian Gulf.
Two Indo-Pacific bottlenose dolphins in the waters of Dolphin’s Bay Natural Heritage at the south of Qeshm Island, eastern Persian Gulf. The right individual shows a behavior known as “rolling belly-up” that usually happens when a female wants to secure its genital slit from unwanted mating by the males. Indo-Pacific bottlenose dolphins are slightly smaller and slender than common bottlenose dolphins (T. truncatus), a cosmopolitan species. Nonetheless, Indo-Pacific bottlenose dolphins can grow up to 2.5 meters in length, and are therefore larger than Indian Ocean humpback dolphins and Indo-Pacific finless porpoises, two other species of the near-shore cetaceans living in the Persian Gulf. Bottlenose dolphins everywhere are attracted to vessels and also in Qeshm they typically fearlessly swim with small boats. Conservation assessment of the species is still impossible due to lack of information and the species is therefore categorized as Data Deficient (DD) by the IUCN Red List of Threatened Species.
- Indian Ocean humpback dolphin (Sousa plumbea): this species is abundant through the entire Persian Gulf. An Indian Ocean humpback dolphin community of about 700 individuals have been recorded from coastal waters of Abu Dhabi in the southeastern Persian Gulf, which was reported as the world’s largest documented population of the species (ref).
An Indian Ocean humpback dolphin in coastal waters of Qeshm Island (Photo: Koen Van Waerebeek). There are four known species of humpback dolphins in the genus Sousa, all of them categorized as threatened species in the IUCN Red List. The Indian Ocean humpback dolphin (Sousa plumbea), the only species of the genus living in the western Indian Ocean, including the Persian Gulf, is categorized as Endangered (EN) in the list. Anthropogenic activities, i.e. fisheries and habitat destruction, are the main threats for cetaceans living in shallow near-shore waters.
- Indo-Pacific finless porpoise (Neophocaena phocaenoides): available data suggest a discontinuous distribution in the northwestern Indian Ocean. The species observed along southern Iranian waters, mostly in the Persian Gulf, but also in the Gulf of Oman. The Gulf is known as the westernmost distribution extent of this small and threatened cetacean.
An Indo-Pacific finless porpoise in the Hara Biosphere Reserve, northern Qeshm Island. A dark back rolling at the surface is the typical recorded view of finless porpoises in their natural habitats. Jefferson et al. (2015) hinted that researchers should be careful as finless porpoises may resemble car tires bobbing in the water. The length of this charismatic small cetacean rarely exceeds 1.5 meters. Therefore, it is among the smallest living cetaceans in the world, and is the smallest cetacean in the Persian Gulf. Because of their small size, finless porpoises are shy animals that usually avoid swimming near boats. There are two species in the genus Neophocaena, both of which occur in the Indo-Pacific region, and both are categorized as threatened in the IUCN Red List. The Indo-Pacific finless porpoise (N. phocaenoides) is categorized as vulnerable (VU) in the list.
Our conservation projects for nearshore small cetaceans in the Persian Gulf:
- Estimating abundance, home-range and threats to Indo-Pacific bottlenose dolphins in Dolphin’s Bay National Monument (Read more)