Results of a Combined Instrumental and Visual Aerial Survey of Cetaceans in the Northeastern Black Sea in 2019

The results of the first combined instrumental and visual aerial cetacean survey in the northeastern Black Sea conducted in July 2019 are presented. The study area of 11 244 km² included the water area within the 12-mile zone of the Black Sea (territorial sea of the Russian Federation) from Sochi to Anapa. The total estimated abundance of cetaceans was 17 505 ± 2678 individuals (CL90% 13 484–22 206). Approximately, the common dolphins made up 69% of this number, the bottlenose dolphins—22%, the harbor porpoises—9%. The maximum density of common dolphins reached 8.13 individuals/km², the bottlenose dolphins—1.87 individuals/km², the harbor porpoises—0.62 individuals/km². All three species have a zone of high density in the northern part of the surveyed area and a zone of low density in its middle part. The data obtained were compared with the results of other Black Sea cetacean surveys. A comparative assessment of instrumental and visual data collection methods was made as part of the aerial survey.