Distribution of three cetacean species along the Bulgarian Black Sea coast in 2006-2013
Marina Panayotova, Valentina Todorova
Institute of Oceanology-BAS, “Parvi may”40 Str., P.O.Box 152, 9000 Varna, BULGARIA
Opportunistic observations of small cetacean species were made on board of fishing vessels and the 55-m research vessel “Akademik” during 20 surveys, carried out between April and November over the period 2006-2013 in the Bulgarian Black Sea territorial waters and exclusive economic zone. Over 10733 nautical miles and 1643 hours of survey effort, 289 sightings were recorded. Three cetacean species – bottlenose dolphin (Tursiops truncatus), common dolphin (Delphinus delphis) and harbour porpoise (Phocoena phocoena) were observed. The most abundant species was the bottlenose dolphin – 618 individuals recorded in 120 sightings, followed by the common dolphin – 554 individuals in 101 sightings and 251 harbour porpoises in 68 sightings. The overall encounter rate was 3.18 sightings/100 nm. The distribution of cetaceans in the Bulgarian Black Sea area was associated with the ecological conditions such as prey dynamics, hydrology, ecosystem productivity, and also with some anthropogenic activities. Due to the absence of specialized surveys on cetaceans, the available sighting data help to elucidate the distribution of cetaceans, thus provide the scientific base for the designation of marine NATURA 2000 sites in the Bulgarian Black Sea for the conservation of marine mammals listed in Annex II of the Habitats Directive.
Keywords: Bulgarian Black Sea area, cetaceans, sightings, distribution