Emona IMMA

Criterion A – Species or Population Vulnerability

Populations of the three cetacean’s species in the Black Sea were assessed in 2008 and listed on the IUCN Red List as: Vulnerable A2cde for the Black Sea common dolphin, EN A2cde for Black Sea bottlenose dolphin and EN A1d+4cde for Black Sea harbour porpoise. Currently, the IUCN conservation status of all three subspecies is being re-assessed based on updated information including two aerial surveys conducted in the past 10 years and evaluation of bycatch levels.

Criterion B: Distribution and Abundance

Sub-criterion B2: Aggregations

Combined visual and acoustic line transect surveys of cetacean abundance were carried out in the IMMA in 2015 and 2017 (Panayotova et.al, 2017, 2020).

In 2015, two of the marine cetacean species were observed – P. p.relicta and T. t. truncatus (Fig.1). The estimated values for density of T. t. ponticus groups and for single animals were 0.108 groups.km-2 and 0.322 ind.km-2. Absolute abundance was estimated as 819 individuals (CV = 25.54%) in the study area and the encounter rate – as 0.066 ind.km-1. Harbour porpoises were observed in the shelf area, mostly in offshore areas at depths of more than 40m (Fig. 1). Density of P. p. relicta groups and single animals was 0.057 groups.km-2 and 0.15 ind.km-2. Absolute abundance was estimated as 380 individuals (CV = 43.46%) in the surveyed area, and encounter rate – as 0.057 ind.km-1. A total of 27 detections of harbour porpoise and 16 of bottlenose dolphin were also made (Fig.1).

In 2017, during a line transect survey covering the whole Bulgarian Black Sea shelf, all three Black Sea cetacean species were observed (Panayotova et.al, 2020). Estimated abundance for common bottlenose dolphin was 1365 individuals (CV = 35.62%, 95% CI: 684 – 2722), densities of groups and single animals were, respectively, 0.0475 groups.km-2 and 0.113 ind.km-2 and the encounter rate – 0.0351 ind.km-1 (Panayotova et.al, 2020). Common dolphins – the estimated values for density of groups and for single animals were 0.0414 groups.km-2 and 0.0796 ind.km-2. Abundance was calculated at 963 individuals (CV = 32.79%, 95% CI: 507 – 1827) in the study area and the encounter rate – as 0.0263 ind.km-1 (Panayotova et.al, 2020). In 2017 Harbour porpoises were the most abundant species with calculated abundance of 6474 individuals (CV = 21.81%, 95% CI: 4227 – 9916), encounter rate of 0.118 ind.km-1 and estimated values for density of groups and for single animals of 0.186 groups.km-2 and 0.536 ind.km-2, respectively.

All three species were observed in 2013 and 2019 in the area during the regional aerial surveys (Paiu et al., 2021, Birkun et.al, 2014).

Historical data on opportunistic sightings during surveys for fish stock assessments in 2006 – 2013 (Panayotova and Todorova, 2015a; Panayotova and Todorova, 2015b) prove the presence of all three species in the area and the use of the area as a feeding ground. During ten vessel transect surveys of Bulgarian territorial waters in the period 2017-2021, mean encounter rate for Black Sea bottlenose dolphin in the proposed area was above average for the entire territorial waters (Popov, 2017-2020).

Criterion C: Key Life Cycle Activities

Sub-criterion C2: Feeding Areas

The bottlenose dolphins feed on both benthic and pelagic fishes, which are abundant in the Emona IMMA. Diversity of substrate and related habitats including mussel beds, reefs and sandbanks combined with permanent currents along Cape Emine define diversity and abundance of fish stocks. The area is among the main fishing grounds along the Bulgarian coast, and there is a  large biomass of the main prey species for dolphins – whiting, anchovy, sprat and red mullet (Panayotova and Todorova, 2015c). Analysis of T. t. ponticus observations in relation to the intensity of fishing activities along the Bulgarian coast indicated the dolphins show a clear preference for the areas with moderate and intensive fishing activities (Panayotova and Todorova, 2015a).