Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area
(1) Background: To date, data concerning the population of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> from the marine waters of Bulgaria are rather scarce. In the range of a project for mapping the Bulgarian marine protected sites from the network NATURA 2000, we provid...
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2025-01-01
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| author | Desislava Rozdina Yana Stoyanova Georgi Terziyski Slavi Studenkov Boris Karakushev Venceslav Delov Konstantin Mihaylov Dimitar Kozhuharov Yordan Kutsarov Nikolay Kolev Nikolay Nedyalkov Nikolay Natchev |
| author_facet | Desislava Rozdina Yana Stoyanova Georgi Terziyski Slavi Studenkov Boris Karakushev Venceslav Delov Konstantin Mihaylov Dimitar Kozhuharov Yordan Kutsarov Nikolay Kolev Nikolay Nedyalkov Nikolay Natchev |
| author_sort | Desislava Rozdina |
| collection | DOAJ |
| description | (1) Background: To date, data concerning the population of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> from the marine waters of Bulgaria are rather scarce. In the range of a project for mapping the Bulgarian marine protected sites from the network NATURA 2000, we provide an intense investigation of the biology and distribution of both <i>Alosa</i> species. (2) Methods: A trawling survey was carried out within 102 predefined sampling plots of 10 × 10 km grid cells (93 cells on the continental shelf, up to 100 m depth, and 9 offshore cells). In some coastal regions, sampling was conducted with gill nets of different mesh sizes (28 mm to 36 mm). Analysis of the suitability of the occupied habitat of both species was carried out using the MAXENT v 3.4.0 software application. The status of the populations was studied based on the parameters abundance (ind./km<sup>−2</sup>), biomass (kg/km<sup>−2</sup>), size, sex structure, maturity, and food spectrum. (3) Results: Out of 102 transects studied, <i>A. immaculata</i> was found in 12 transects and <i>A. tanaica</i> in 13. A total of 408 fish specimens were captured, out of which 313 were <i>A. immaculata</i> and 95 were <i>A. tanaica</i>. Both species were distributed along Bulgaria’s entire Black Sea coast, with a numerical prevalence of the catches in the southern part. The population size of <i>A. immaculata</i> for the number of individuals on a biographical level in the Marine Black Sea Biographic Region (MBLS) was a minimum of 100,255 individuals and a maximum of 526,408 individuals (the average was 313,286). The population size for <i>A. tanaica</i> was a minimum of 28,183 individuals and a maximum of 449,549 individuals (an average of 238,866). The current population density of <i>A. immaculata</i> in the MBLS was 25.98 ind./km<sup>−2</sup>, and for <i>A. tanaica</i>, it was 19.00 ind./km<sup>−2</sup>. The current biomass of the population of <i>A. immaculata</i> in the MBLS was 3.44 kg/km<sup>−2</sup>, and the population of <i>A. tanaica</i> was 0.53 kg/km<sup>−2</sup>. The sex ratio for <i>A. immaculata</i> was 1 male:2.6 females, and for <i>A. tanaica</i>, 1 male:3.8 females. Both shad species were feeding with less intensity or not feeding during the winter. The diversity in the food spectrum of <i>A. tanaica</i> was more limited compared to that of <i>A. immaculata</i>. (4) Conclusions: Key parameters for the Bulgarian Black Sea Exclusive Economic Zone indicate current stability in the resources of <i>A. immaculata</i> and <i>A. tanaica</i> and more favorable conditions for the populations in the Natura 2000 sites compared to that outside the Natura 2000. The results of this study should be used to develop management plans for marine protected areas, and future monitoring projects should follow the sampling protocol. |
| format | Article |
| id | doaj-art-909c9e54114144fea96b54c9ad21ef1b |
| institution | Kabale University |
| issn | 1424-2818 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
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| spelling | doaj-art-909c9e54114144fea96b54c9ad21ef1b2025-01-24T13:29:27ZengMDPI AGDiversity1424-28182025-01-011713810.3390/d17010038Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea AreaDesislava Rozdina0Yana Stoyanova1Georgi Terziyski2Slavi Studenkov3Boris Karakushev4Venceslav Delov5Konstantin Mihaylov6Dimitar Kozhuharov7Yordan Kutsarov8Nikolay Kolev9Nikolay Nedyalkov10Nikolay Natchev11Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tsankov Str., 1164 Sofia, BulgariaFaculty of Industrial Technology, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1756 Sofia, BulgariaIndependent Researcher, 1680 Sofia, BulgariaIndependent Researcher, 1336 Sofia, BulgariaIndependent Researcher, 1415 Sofia, BulgariaFaculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tsankov Str., 1164 Sofia, BulgariaInstitute of Fisheries—Varna, 4 Primorski Blvd., 9000 Varna, BulgariaFaculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tsankov Str., 1164 Sofia, BulgariaDepartment of Biological Science, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, BulgariaDepartment of Biology, Shumen University, 115 Universitetska Str., 9700 Shumen, BulgariaDepartment of Biology, Shumen University, 115 Universitetska Str., 9700 Shumen, BulgariaDepartment of Biology, Shumen University, 115 Universitetska Str., 9700 Shumen, Bulgaria(1) Background: To date, data concerning the population of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> from the marine waters of Bulgaria are rather scarce. In the range of a project for mapping the Bulgarian marine protected sites from the network NATURA 2000, we provide an intense investigation of the biology and distribution of both <i>Alosa</i> species. (2) Methods: A trawling survey was carried out within 102 predefined sampling plots of 10 × 10 km grid cells (93 cells on the continental shelf, up to 100 m depth, and 9 offshore cells). In some coastal regions, sampling was conducted with gill nets of different mesh sizes (28 mm to 36 mm). Analysis of the suitability of the occupied habitat of both species was carried out using the MAXENT v 3.4.0 software application. The status of the populations was studied based on the parameters abundance (ind./km<sup>−2</sup>), biomass (kg/km<sup>−2</sup>), size, sex structure, maturity, and food spectrum. (3) Results: Out of 102 transects studied, <i>A. immaculata</i> was found in 12 transects and <i>A. tanaica</i> in 13. A total of 408 fish specimens were captured, out of which 313 were <i>A. immaculata</i> and 95 were <i>A. tanaica</i>. Both species were distributed along Bulgaria’s entire Black Sea coast, with a numerical prevalence of the catches in the southern part. The population size of <i>A. immaculata</i> for the number of individuals on a biographical level in the Marine Black Sea Biographic Region (MBLS) was a minimum of 100,255 individuals and a maximum of 526,408 individuals (the average was 313,286). The population size for <i>A. tanaica</i> was a minimum of 28,183 individuals and a maximum of 449,549 individuals (an average of 238,866). The current population density of <i>A. immaculata</i> in the MBLS was 25.98 ind./km<sup>−2</sup>, and for <i>A. tanaica</i>, it was 19.00 ind./km<sup>−2</sup>. The current biomass of the population of <i>A. immaculata</i> in the MBLS was 3.44 kg/km<sup>−2</sup>, and the population of <i>A. tanaica</i> was 0.53 kg/km<sup>−2</sup>. The sex ratio for <i>A. immaculata</i> was 1 male:2.6 females, and for <i>A. tanaica</i>, 1 male:3.8 females. Both shad species were feeding with less intensity or not feeding during the winter. The diversity in the food spectrum of <i>A. tanaica</i> was more limited compared to that of <i>A. immaculata</i>. (4) Conclusions: Key parameters for the Bulgarian Black Sea Exclusive Economic Zone indicate current stability in the resources of <i>A. immaculata</i> and <i>A. tanaica</i> and more favorable conditions for the populations in the Natura 2000 sites compared to that outside the Natura 2000. The results of this study should be used to develop management plans for marine protected areas, and future monitoring projects should follow the sampling protocol.https://www.mdpi.com/1424-2818/17/1/38ecologyfishconservationbio-resourcesreproductionsustainability |
| spellingShingle | Desislava Rozdina Yana Stoyanova Georgi Terziyski Slavi Studenkov Boris Karakushev Venceslav Delov Konstantin Mihaylov Dimitar Kozhuharov Yordan Kutsarov Nikolay Kolev Nikolay Nedyalkov Nikolay Natchev Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area Diversity ecology fish conservation bio-resources reproduction sustainability |
| title | Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area |
| title_full | Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area |
| title_fullStr | Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area |
| title_full_unstemmed | Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area |
| title_short | Mapping the Distribution and Population Status of <i>Alosa immaculata</i> and <i>Alosa tanaica</i> (Teleostei, Clupeidae) in the Bulgarian Black Sea Area |
| title_sort | mapping the distribution and population status of i alosa immaculata i and i alosa tanaica i teleostei clupeidae in the bulgarian black sea area |
| topic | ecology fish conservation bio-resources reproduction sustainability |
| url | https://www.mdpi.com/1424-2818/17/1/38 |
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