LIVING AT THE LIMITS: Distribution of Small Cetaceans along Abu Dhabi Waters, Arabian Gulf, United Arab Emirates

Abstract

The Emirate of Abu Dhabi is strategically located within the Arabian Gulf in a combination of geographical, oceanographic and ecological conditions which enable the presence of a rich cetacean fauna. Although the preservation of suitable habitats is necessary, the persistence of cetacean species in Abu-Dhabi waters cannot occur without a better understanding of their distribution, demography and use of habitat. Here we report the distribution patterns and group dynamic of cetacean species as integral components of the information needed to manage human impacts on marine mammals in Abu Dhabi waters. Overall, 13 days were spent at sea in April 2017, totaling 107 hours and 1 145 km of boat-based observations. During this time there were 57 encounters with cetaceans (35 with Indo-pacific bottlenose dolphins, 14 with Indian Ocean humpback dolphins, and 8 with finless porpoises). During these encounters 268 Indo-pacific bottlenose dolphins, 92 Indian Ocean humpback dolphins, and 37 finless porpoises were observed. These surveys confirm Abu Dhabi waters as an important foraging habitat for all these cetacean species. Indeed, behavioural data confirm Abu Dhabi waters as a breeding/nursery zone for Indian Ocean humpback dolphins and Indo-pacific bottlenose dolphins. Although the Abu-Dhabi humpback dolphin population is considered one of the largest in the genus Sousa in the world, based on previous studies, the observed decline in presence of humpback dolphins could be cause of concern. A number of interacting factors may have played a role in this decline, ranging from natural fluctuations to the potential impact of human activities such as oil and gas exploration (including seismic surveying) in the Central region during the surveys period. Therefore, further surveys are needed to confirm if this decline is result of a short-term seasonal variation in presence or on the contrary, is due to a real decline in the occurrence of this endangered species.

Full text

LIVING AT THE LIMITS: Distribution of Small Cetaceans along
Abu Dhabi Waters, Arabian Gulf, United Arab Emirates
Ibrahim Bugla1, Bruno Díaz López2, Séverine Methion2, Himansu Das1, Maitha Al Hameli1, Amna Al Mansoori1, Hind Al Ameri1 and Ahmed Al Hashmi1
1Environment Agency – Abu Dhabi, P.O. Box 45553, Abu Dhabi, United Arab Emirates. 2The Bottlenose Dolphin Research Institute (BDRI), Av Beiramar 192, O Grove 36980, Pontevedra, Spain.
Corresponding author email: ibugla@ead.gov.ae
CONCLUSIONS
 Abu Dhabi waters are an important foraging habitat and a
breeding/nursery zone for all these cetacean species.
 The observed decline in presence of humpback dolphins
compared to previous EAD dolphin surveys (2014 - 2015)
could be cause of concern.
 A number of interacting factors may have played a role in
this decline, ranging from natural fluctuations to the poten-
tial impact of human activities
Figure1 Map of the study area showing the cetacean encounters (dolphins
and porpoises) and the different tracks surveyed across the Abu Dhabi coast-
line.
RESULTS
• 57 encounters with cetaceans (35 with Indo-pacific bottle-
nose dolphins, 14 with Indian Ocean humpback dolphins,
and 8 with finless porpoises).
• 268 Indo-pacific bottlenose dolphins, 92 Indian Ocean hump-
back dolphins, and 37 finless porpoises were observed.
(Fig.2).
• Indo-pacific bottlenose dolphin (Fig 3,5) was the most com-
monly seen cetacean species along Abu Dhabi waters
(Kruskal-Wallis test, p<0.05).
• The occurrence of the observed species showed spatial fluc-
tuations along the Abu-Dhabi waters (Figure 4). Indo-pacific
bottlenose dolphins showed preferences for the Western re-
gion, however the occurrence of both Indian Ocean hump-
back dolphins and finless porpoises was homogeneous
across the monitored regions.
INTRODUCTION
• The Emirate of Abu Dhabi is strategically located within the Arabian Gulf in a
combination of geographical, oceanographic and ecological conditions
which enable the presence of a rich cetacean fauna. Although the preserva-
tion of suitable habitats is necessary, the persistence of cetacean species in
Abu-Dhabi waters cannot occur without a better understanding of their dis-
tribution, demography and use of habitat.
• Here we report the distribution patterns and group dynamic of cetacean
species as integral components of the information needed to manage hu-
man impacts on marine mammals in Abu Dhabi waters.
Figure 2 Distribution of the
number of small cetaceans ob-
served during the study.
Figure 5 Indo-pacific bottlenose dolphins (Tursiops aduncus ) ob-
served during dolphin surveys in the southern Arabian Gulf.
Figure 6 Indian Ocean hump-
back dolphin (Sousa plumbea)
seen during the surveys
ACKNOWLDEDGEMENTS
We would like to thank H.E Dr. Shaikha Al Dhaheri and EAD management for supporting this work. The dolphin surveys were implemented by the Marine
Assessment & Conservation Section, Environment Agency-Abu Dhabi.
METHODS
• Overall, 13 days were spent at sea in April 2017, totaling 107 hours and
1145 km of boat-based observations.
• Photo-Identification Analysis
• Temporal and spatial distribution
• Group dynamics
Figure 4 Overall cetacean
encounter ratio (Sightings per
hour searching) across the
three monitored regions.
Figure 3 Encounter ratio for
all three cetacean species
across the three monitored re-
gions.
Figure 7 Indo-pacific fin-
less porpoise (Neophocoena
phocaenoides) seen during
the surveys