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Abu Dhabi leads world in humpback dolphin numbers

Abu Dhabi - The Environment Agency (EAD) - Abu Dhabi's 'Dolphin Survey', estimated that 701 Indian Ocean humpback dolphins inhabit Abu Dhabi's coastal waters.

A first of its kind survey has revealed that Abu Dhabi is home to the world's largest population of Indian Ocean humpback dolphins.
The Environment Agency (EAD) - Abu Dhabi's 'Dolphin Survey', estimated that 701 Indian Ocean humpback dolphins inhabit Abu Dhabi's coastal waters.
It is the largest-ever reported population of these species in the world with South Africa marking a population of 466, Mozambique 105, Kenya 104 and Tanzania 63.
As per the findings, 1,834 Indo-Pacific bottlenose dolphins are estimated to live in Abu Dhabi's coastal waters.
Razan Khalifa Al Mubarak, EAD secretary-general, said: "Dolphins are apex predators that bio-accumulate marine toxins, consequently, they are good indicators of marine environmental quality. As very little was known about the ecology and conservation status of dolphin species in Abu Dhabi waters, EAD started a dolphin survey in 2014. This has provided population size estimates and information on the main threats, which is required as a basis for the assessment, monitoring and conservation of these charismatic species." 
To date, 64 days of vessel-based surveys have been completed covering 5,592 kilometres of survey track. In addition to the Indian Ocean humpback dolphins (Sousa plumbea), 693 Indo-Pacific bottlenose dolphins (Tursiops aduncus), and 52 finless porpoises (Neophocaena phocaenoides) were recorded.
Edwin Grandcourt, manager, marine assessment and conservation section, EAD, told Khaleej Times that the survey was conducted on a customised 45-foot research boat with elevated platforms.
"We conduct surveys during the spring and winter months, and there are five people aboard the vessel at any given time. Each survey lasts for three weeks, and they are conducted during daylight hours. We conduct systematic search for dolphins. When we encounter them, we take environmental readings, and also photograph the dorsal fins at the back of the dolphins."
According to him, each dolphin has distinctive cuts, notches and scars at the trail end of the dorsal fins that help researchers distinguish them individually, much like a human face. 
"The dolphins may come two to three metres close to the vessel or sometimes are spotted 50 or 60 metres away. But we have zoom lenses with which we can photograph them. Once we comeback from the survey, the photographs are analysed and the individual fins are digitised to create a database of all the animals we have seen. That is used to compile a photo ID catalogue," said Grandcourt.
And using a 'Mark Recapture' method, the population size is estimated based on re-sighting of dolphins. He said though the number of Indian Ocean humpback dolphins look significantly high, it is still small and the species remain vulnerable especially as they inhabit shallow water where human activities coincide.
"The survey is crucial as the research findings will be put into a conservative management plan that will help us formulate policies and guidelines for dolphin conservation in Abu Dhabi."
anjana@khaleejtimes.com