In the period 29 April - 4 May, a team of Green Balkans’ experts and volunteers executed a vessel survey on abundance, distribution and density of cetaceans’ population in Bulgarian territorial waters of the Black Sea. Territorial sea of Bulgaria includes strip with a width of 12 nautical miles adjacent to the coast and the internal waters measured from the baselines with total area of 6 358 sq. km.
The internationally proven and used technique of distance sampling along line transects was used. The survey plan used in previous years was used – developed by Distance 7.0 software and including 13 transects with total length of 458 km on effort ensuring coverage of 7% on study area. Main limiting factor for the successful execution of the survey was the meteorological conditions at sea as for the visual observations were needed good conditions – low wind and waves. During the week when the survey was made only one interruption of one day was enforced by bad weather. That was the fastest completed survey until now deploying the same survey plan as in previous years.
The survey team successfully covered 444 km on effort from the planned transects during favourable weather conditions within 5 days. During the survey, the observers recorded 168 sightings in total with 440 individuals. Most numerous were encounters of Black sea harbor porpoises (Phocoena phocoena relicta) – 137 followed by Black sea bottlenose dolphins (Tursiops truncatus ponticus) with 16 sightings, while Black sea common dolphins (Delphinus delphis ponticus) were encountered at 15 occasions.
The current survey is the fourth one organized by Green Balkans NGO deploying the same design in order to monitor trend in distribution, density and abundance of cetaceans in Bulgarian territorial waters. This year the coverage was bigger – 444 km of line transects compared to 441 km last year. Number of sightings this year was three times higher compared to June 2018 when only 55 sightings were recorded. Highest density was recorded in northern sector – waters adjacent to Dobrogea between Cape Kaliakra and Romanian border. Unlike previous years largest observed group this time was of migrating porpoises that were associated with Yelkouan shearwaters and were more than 20.
Collection of information on distribution and abundance of cetaceans is important for conservation of these enigmatic species. Data from the survey will be analyzed so to get an estimation of abundance for different species in the relevant period.
We would like to thank experts and volunteers Galina Meshkova, Polina Hristova, Antonia Miteva, Nikolay Davidkov and Petya Parikova who have proven as experience observers once again and allowed continuity of the study. Special thanks to captain Georgiev with “Kaliakria” yacht for the professional logistic support.
The survey was made possible thanks to the generous funding provided by OceanCare (www.oceancare.org).
Contacts:
Dimitar Popov - Green Balkans NGO
mob. number: +359885108712, e-mail: dpopov@greenbalkans.org
The internationally proven and used technique of distance sampling along line transects was used. The survey plan used in previous years was used – developed by Distance 7.0 software and including 13 transects with total length of 458 km on effort ensuring coverage of 7% on study area. Main limiting factor for the successful execution of the survey was the meteorological conditions at sea as for the visual observations were needed good conditions – low wind and waves. During the week when the survey was made only one interruption of one day was enforced by bad weather. That was the fastest completed survey until now deploying the same survey plan as in previous years.
The survey team successfully covered 444 km on effort from the planned transects during favourable weather conditions within 5 days. During the survey, the observers recorded 168 sightings in total with 440 individuals. Most numerous were encounters of Black sea harbor porpoises (Phocoena phocoena relicta) – 137 followed by Black sea bottlenose dolphins (Tursiops truncatus ponticus) with 16 sightings, while Black sea common dolphins (Delphinus delphis ponticus) were encountered at 15 occasions.
The current survey is the fourth one organized by Green Balkans NGO deploying the same design in order to monitor trend in distribution, density and abundance of cetaceans in Bulgarian territorial waters. This year the coverage was bigger – 444 km of line transects compared to 441 km last year. Number of sightings this year was three times higher compared to June 2018 when only 55 sightings were recorded. Highest density was recorded in northern sector – waters adjacent to Dobrogea between Cape Kaliakra and Romanian border. Unlike previous years largest observed group this time was of migrating porpoises that were associated with Yelkouan shearwaters and were more than 20.
Collection of information on distribution and abundance of cetaceans is important for conservation of these enigmatic species. Data from the survey will be analyzed so to get an estimation of abundance for different species in the relevant period.
We would like to thank experts and volunteers Galina Meshkova, Polina Hristova, Antonia Miteva, Nikolay Davidkov and Petya Parikova who have proven as experience observers once again and allowed continuity of the study. Special thanks to captain Georgiev with “Kaliakria” yacht for the professional logistic support.
The survey was made possible thanks to the generous funding provided by OceanCare (www.oceancare.org).
Contacts:
Dimitar Popov - Green Balkans NGO
mob. number: +359885108712, e-mail: dpopov@greenbalkans.org
