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

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.