Northern Gulf and Confluence of the Tigris, Euphrates and Kuran IMMA

Size in Square Kilometres

4 220 km2

Qualifying Species and Criteria

Indian Ocean humpback dolphin – Sousa plumbea

Criterion A; B(1)

Marine Mammal Diversity 

Neophocaena phocaenoides, Sousa plumbea, Tursiops aduncus

Summary

This IMMA at the northernmost tip of the Arabian/Persian Gulf comprises the delta created by the confluence of the Euphrates, Tigris, and Kuran rivers extending to estuarine environments on the eastern side of Musa Bay (Ra’s-e Barkan). This transboundary area shared by Kuwait, Iraq and Iran is characterised by very shallow waters and a number of Islands. The area includes important habitat for Endangered Indian Ocean humpback dolphins (Sousa plumbea). Dedicated surveys have yielded encounter rates and abundance estimates for this species in two core areas surrounding Boubyan Island (Kuwait) and Musa Bay (Iran). Finless porpoises (Neophocaena phocaenoides)  are also likely to occur in this area.

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

Indian Ocean Humpback Dolphins are considered “Endangered” in the IUCN Red List (Braulik et al., 2017). This area has been defined of importance for humpback dolphins based on evidence from two dedicated surveys and a number of incidental sightings across an estuarine environment with similar habitat parameters (Bishop and Alsafar, 2008; Himami et al. 2018; Braulik et al, 2010). From Kuwait based surveys Bishop and Alsafar (2008) report the humpback dolphins encountered were morphologically closer to Sousa plumbea although the publication formally refers to them as Sousa chinensis (based on waiting for taxonomic resolution of the species). Humpback dolphins within this range are now classified as Sousa plumbea (Mendez et al., 2013; Braulik et al. 2015; Braulik et al 2017).

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations 

Sousa plumbea populations generally exhibit high grade of residency (Braulik et al., 2015). Surveys conducted in northern waters of Kuwait from circumnavigation of Boubyan Island between 2004 to 2005 resulted in a total count of 524 animals with the maximum number encountered in one day of 66 individuals resulting in a conservative estimate of at least 100 animals (Bishop and AlSafar, 2008). Surveys were often completed by circumnavigation of Boubyan Island in one day. Marine mammal observations were recorded within periods of dedicated observation periods (and recorded to nearest minuet). Dolphins were present through the year with a bimodal distribution of encounter rates, with peaks in April (3.3/h) and September (1.8/h). The maximum number of individuals encountered in a day along one continuous transect was 66 and extrapolations resulting in conservative estimate of at least 100 individuals in the area. Based on year-round observations they are considered to be resident. From Iranian waters of the IMMA Hemami (2018) details encounters from ‘distance’ based line transect surveys conducted between December 2014 and February 2016 in Mousa Bay, part of the Shadegan wildlife refuge. 1273km of line transect surveys resulted in encounters with 75 humpback dolphin groups, producing an encounter rate of 0.058 groups/km. Mean group size was 2.71 dolphins per group with a range from 1-15 animals. An abundance of 92 animals was calculated for this area (95% CI 64-131) and density of 0.123 (95% CI 0.086-0.176). In evaluation of explanatory environmental variables, the authors noted that the highest densities were found within 1-2km from the shore, water depth of 30m and highest densities of chlorophyll a. Overall, although preliminary, these data support the existence of a likely small population with a high peak of residency in the present area. In addition the data available for this area is limited, during their survey Bishop and Alsafar (2008) reported commonly observing adults with juveniles. Finally, Bishop and Alsafar (2008) reported behaviour of dolphins in the middle of the channel where dive times were long and indicated feeding. Cooperative feeding behaviour was also mentioned observed in shallow waters and on one occasion a group of 10 were observed working a shoal of Gulf Herring (Herklotsichthys lossei). Considering the likely residency of this species in the area, based on the available data and the behaviour observed it is plausible that the area is utilised also as feeding ground.

Supporting Information

Al – Robaae, K. 1970. First record of the speckled dolphin, Sotalia lentiginosa Gray, 1866, in the Arabian Gulf. Saügetierk Mit.,18: 227 – 228.

Al – Robaae, K. 1974. Tursiops aduncus, bottlenose dolphin: A new record for the Arabian Gulf, with notes on cetacean of the region. Bull. Basrah. Nat. Hist. Mus., p. 7 -16.

Baldwin, R., Van Waerebeek, K. and Gallagher, M., 1998. A review of small cetaceans from waters off the Arabian Peninsula. IWC SC/50/SM6, pp.1-24.

Bishop, J. M. & Alsaffar, A. H. 2008. Quantitative observations on marine mammals and reptiles of Kuwait’s Boubyan Island, Zoology in the Middle East, 43:1, 3-12, DOI: 10.1080/09397140.2008.10638263

Braulik, G.T., Ranjbar, S., Owfi, F., Aminrad, T., Dakhteh, S.M.H., Kamrani, E. and Mohsenizadeh, F., 2010. Marine mammal records from Iran. Journal of Cetacean Research and Management, 11:1, pp.49-63.

Braulik, G.T., Findlay, K., Cerchio, S. and Baldwin, R., 2015. Assessment of the conservation status of the Indian Ocean humpback dolphin (Sousa plumbea) using the IUCN Red List criteria. In Advances in marine biology (Vol. 72, pp. 119-141). Academic Press.

Braulik, G.T., Findlay, K., Cerchio, S., Baldwin, R. and Preen, W., 2017. Sousa plumbea. The IUCN Red List of Threatened Species 2017: e. T82031633A82031644.

Collins, T., Preen, A., Willson, A., Braulik, G. and Baldwin, R.M., 2005. Finless porpoise (Neophocaena phocaenoides) in waters of Arabia, Iran and Pakistan. International Whaling Commission, Scientific Committee Document SC/57/SM6. Cambridge, UK.

Jefferson, T.A. and Hung, S.K., 2004. A review of the status of the Indo-Pacific humpback dolphin (Sousa chinensis) in Chinese waters. Aquatic Mammals, 30:1, 149-158.

Hemami, M.R., Ahmadi, M., Sadegh-Saba, M. and Moosavi, S.M.H., 2018. Population estimate and distribution pattern of Indian Ocean humpback dolphin (Sousa plumbea) in an industrialised bay, northwestern Persian Gulf. Ecological indicators, 89: 631-638.

Henningsen, T. and Constantine, R., 1992. Cetaceans in the Persian Gulf: after the war. European Research on Cetaceans, 6: 108-113.

Mendez, M., Jefferson, T.A., Kolokotronis, S.O., Krützen, M., Parra, G.J., Collins, T., Minton, G., Baldwin, R., Berggren, P., Särnblad, A. and Amir, O.A., 2013. Integrating multiple lines of evidence to better understand the evolutionary divergence of humpback dolphins along their entire distribution range: a new dolphin species in Australian waters?.Molecular ecology, 22:23, 5936-5948.

Mohamed, A.R.M & Hussain, N.A. (1998) Observations On the Occurrence of Bottlenose Dolphins Tursiops truncates in Iraqi waters. Marine Mesopotamica 13:2, 409-415

Nithyanandan, M., 2010. Opportunistic sightings of Indo-Pacific humpback dolphin, Sousa chinensis from Kuwait waters with notes on their behaviour. J. of the Marine Biological Association of India, 52:1, 19-23.

Preen, A., 2004. Distribution, abundance and conservation status of dugongs and dolphins in the southern and western Arabian Gulf. Biological Conservation, 118(2), pp.205-218.

Reeves, R.R., Wang, J.W., Leatherwood, S. (1997). The Finless Porpoise, Neophocaena phocaenoides (G. Cuvier, 1829): A Summary of Current Knowledge and Recommendations for Conservation Action. Asian Marine Biology 14: 111-143.

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