Black Sea Eastern Anatolian Coast IMMA

Criterion A – Species or Population Vulnerability

All three Black Sea subspecies, Black Sea Bottlenose Dolphin Tursiops truncatus ponticus, Black Sea Common Dolphin Delphinus delphis ponticus, and Black Sea Harbour Porpoise Phocoena phocoena relicta, are sighted in this IMMA, but their densities change according to the season and locations due to variations in prey abundance and environmental factors. Harbour porpoises and Bottlenose dolphin is currently listed as Endangered and Common dolphin as Vulnerable in IUCN RedList.

Criterion B: Distribution and Abundance

Sub-criterion B2: Aggregations

Survey data show that common dolphins (Delphinus delphis) are widely observed across the IMMA.The heat map generated from CeNoBS surveys conducted in 2019 shows aggregations of this species in the western part of the IMMA off Sinop to Samsun, but they are also widely distributed along the entire coast and extend to offshore areas. Harbour porpoise are present in the narrow coastal strip in waters less than 1000m deep. Bottlenose dolphins (Tursiops truncatus) are very rare compared to the above two species and there was no sighting in some surveys.

In a study conducted in the Southern Black Sea in 2022 (Özsandıkçı et al., 2022), a total of 849 cetacean groups were recorded, with 448 groups (1846 individuals) during winter and 401 groups (947 individuals) during summer. Encounter rates in the eastern and western regions of Sinop revealed noteworthy distinctions. In winter, encounter rates for bottlenose dolphins were 0.03 ind/km in the east and 0.14 ind/km in the west, for common dolphins, 0.92 ind/km in the east and 0.68 ind/km in the west, and for harbour porpoises, 0.79 ind/km in the east and 0.47 ind/km in the west. During the summer season, encounter rates were 0.14 in/km in the east and 0.07 ind/km in the west for bottlenose dolphins, 0.47 ind/km in the east and 0.26 ind/km in the west for common dolphins, and 0.35 ind/km in the east and 0.14 ind/km in the west for harbour porpoises. These findings demonstrate a more concentrated distribution of cetaceans, particularly common dolphins and harbour porpoises, in the eastern region of Sinop, emphasising the significance of this area for cetaceans.

Criterion C: Key Life Cycle Activities

Sub-criterion C2: Feeding Areas

Stomach content analyses show that all three species feed on wide range of fish species in the Black Sea. Therefore, their food items vary according to the available food resources. Main species for harbour porpoise are anchovy, sprat, whiting, gobies. Anchovy and sprat is also the main prey for common dolphins. Whiting, turbot and mullet species (Lisa spp., Mugil cephalus and M. so-iuy) are favourable for bottlenose dolphins (Birkun 2002)

The narrow strip of coastal water less than 200 m in depth is rich in many demersal and pelagic species (Daskalov et al. 2012). Demersal fish species (red mullet and whiting) are common in the area all year around. One of the main preys of Black Sea common dolphins and harbour porpoises, anchovy becomes and horse mackerel winter in the area. The decline of prey fish resources, resulting in reduced prey availability, has a strong influence mainly on common dolphins and harbour porpoises (Birkun 2002; Tonay et al. 2007; Birkun et al. 2014). The presence and movements of small cetaceans in the IMMA is due to prey availability or scarcity and their concentration in this IMMA is due to the rich habitat supporting anchovy, horse mackerel, blue fish and bonito, all littoral zone species that are cetacean prey (Bilgin et al. 2018).