Update from the Field

HUMPBACK DOLPHINS, HUMPBACK DOLPHINS… WHERE ART THOU?

FEATURE BRYANA COPE & ADA NATOLI – UAE DOLPHIN PROJECT INITIATIVE & ZAYED UNIVERSITY

COVER PHOTO: Indian Ocean humpback dolphins are named for their characteristic “hump” in front of the small dorsal fin.

The Indian Ocean humpback dolphin (Sousa plumbea) inhabits the coastal waters of eastern Africa, the Red Sea, the Arabian Gulf, Pakistan, all the way down to Sri Lanka along the Indian west coast. It has been recognised as a new species only recently in 2014 after morphologic and genetic studies proved its identity was different from the closely related easternmost form, Sousa chinensis. This new species is listed as Endangered by the IUCN Red List (Braulik et al, 2017).

Indian Ocean humpback dolphins are frequently observed socialising, interacting with other peers or young, often performing quite elaborated displays of activities.

Indian Ocean humpback dolphins prefer very coastal, shallow water, and this make their habitat highly impacted by anthropogenic pressures, especially as large cities expand toward the ocean. They are generally resident species, meaning that groups do not travel long distances and prefer to stick together in the same location.

Indian Ocean humpback dolphins are frequently observed socialising, interacting with other peers or young, often performing quite elaborated displays of activities.

Globally, there is very little information on the status of local populations and the specific threats they face as there is no dedicated research in place in many countries across the species’ range. This is especially true in the Gulf. Here, humpback dolphins are known to occur in some part of the Iranian coastline (Mohsenian et al., 2022), in Kuwait, in the Gulf of Salwa, bordering Saudi Arabia, Qatar and Bahrain (Preen 2004). Interestingly, this species frequents the Musandam area, then disappears along the UAE and Omani Indian Ocean coastline until Sur (Oman).

Indian Ocean humpback dolphins are frequently observed socialising, interacting with other peers or young, often performing quite elaborated displays of activities.

Recent surveys conducted in the Abu Dhabi Emirate in 2014-2015, estimated a population of Indian Ocean humpback dolphins between 473-845 individuals (Lopez et al., 2017). The authors identified 220 different individuals overall, but only 2% of those were re-sighted in different areas of their original one, confirming the high site fidelity of this species, extending no more than 100km.

Indian Ocean humpback dolphins are frequently observed socialising, interacting with other peers or young, often performing quite elaborated displays of activities.

The UAE Dolphin Project Initiative and Zayed University have been in the field surveying Dubai waters since February 2021 with the research still ongoing, thanks to the support of our sponsors Atlantis the Palm, Dubai and F3 Marine. Sightings of Indo-Pacific bottlenose dolphins have been frequent and sightings of Indo-Pacific finless porpoises, while less, have also been relatively common. However, in the first year of the surveys there were no sightings of Indian Ocean humpback dolphins. This data is in sharp contrast with the results obtained during the previous survey conducted in Dubai waters in 2013-2014. During that period, humpback dolphin sightings were the most frequent, with 8 sightings recorded. A total of 23 individuals were identified, of which about 40% were resighted more than once during the survey period.

The project has also been collecting citizen science data since 2012, and the sightings reported by the public were analysed up until April 2019. During that period, there were 484 reported sightings in the Arabian Gulf and the Sea of Oman. Of those 103 were reported in Dubai waters, indicating an average of 16 sightings a month of this species in its waters (Natoli et al., 2021). Citizen science data from May 2019 has only reported 5 sightings of humpback dolphins until now. While population estimates have not yet been calculated in Dubai waters, the drastic change in occurrence is a sign of concern.

A group of four Indian Ocean humpback dolphins getting ready for a longer dive. Humpback dolphins generally perform a “tail up” before a descent.

But there is hope! A sighting of humpback dolphins was reported by the public in early 2022 and while the survey continued, the team kept surveying coastal waters in hope of sighting humpback dolphins for themselves. Knowing their preferred coastal habitat, the team designed a specific survey along the coast specifically to intensify the coverage in their preferred habitat. Finally, in late March 2022, the team had a sighting! A tail fluke was spotted and the characteristic hump in front of the small dorsal fin was seen. The animals were, as always, very close to shore, less than 500m from a rocky wave break, in a group of less than 10 individuals. The team stayed with the animals for over 2 hours taking photos for photo ID analysis and observing their behaviour. The animals were travelling very slow, socialising with each other and performing tail slaps, backflips, and scouting the boat with inverted swimming and chuffing.

The team is in the process of analysing the photo IDs, but at least one individual was recognised from the previous years. This individual was also recognised in the sighting reported by the public in early 2022 as well. This shows promise that humpback dolphins still occur in Dubai waters, while less frequent, they are still present.

We don’t exactly know what causes this drastic decline in occurrence of this species in Dubai waters, and continuous monitoring is crucial to pinpoint the more compelling threats. The results from the recent publication of citizen science data in the Gulf concluded that a large proportion of suitable habitat for humpback dolphins is impacted by the anthropogenic presence in Dubai and Abu Dhabi, therefore developing and implementing dedicated mitigation measures to protect this species is crucial (Natoli et al., 2021).

This sighting highlights the need for continued monitoring of Dubai waters and the importance of public involvement. Citizen science has been a crucial component to the UAE Dolphin Project, showing how impactful the public can be in aiding scientific studies. If you are lucky enough to spot dolphins, no matter the species, please report them to sighting@uaedolphinproject.org!

Photos help to confirm the presence and species, and approximate location helps in analysing habitat preference and occurrence.

Keep your eyes peeled when at sea and Keep Reporting!

Despite their considerable sturdy body size and capabability to swim long distances, they do not like offshore waters and are usually found very close to the coastline.

REPORT YOUR SIGHTINGS!

WHAT TO DO TO HELP: If you encounter a whale or a dolphin, collecting information is extremely useful to us.

1) Take videos or photos (if you can). You are there in that moment so you are the scientist. Only you can make a difference. Every image of any quality is better than nothing and will help experts to confirm the species. If you can take photographs and videos when you are on the side of a whale or dolphins so the fins are clearly visible, it can help scientists track the individuals, but please keep a safe distance!

2) CALL as soon as possible if you are witnessing a special sighting or you encounter a dead animal so experts can hopefully reach the site and gather more information.

3) Take note of the date, time, and approximate location – if GPS is not available, a dot on google maps works great! Also report how many individuals you see.

4) Share your data with us: www.uaedolphinproject.org

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