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    Distribution and composition of seafloor marine litter in the southeastern Black Sea
    (Turkish Marine Research Foundation-Tudav, 2020) Kasapoglu, Nazli; Dagtekin, Murat; Ilhan, Salih; Erik, Gokhan; Ozsandikci, Ugur; Buyukdeveci, Ferhat
    This study was conducted to investigate seafloor marine litter abundance between Samsun (Yakakent) and Hopa within the scope of Integrated Marine Pollution Monitoring Project (CSB/CEDIDGM-TUBITAK/MAM) in summer 2019. Totally, the trawl hauling operations were successfully performed in 30 stations. The works were done according to the MEDITS protocol: sampling was done at 3 different depths (0-20 m, 20-50 m and 50-100 m), marine litter was classified in 9 categories. At all sampling stations marine litter was assessed by weight and amount. The most common marine litter group was L2 tire/rubber by weight (53%) and amount (67%) when L1 plastic group - 25% by weight and L5 fabric and natural fibres - 12% by amount. Especially in the L2 group, the car and truck tires were dominated in weight of CB5 (Trabzon- Surmene) and CB3 (Trabzon) stations.
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    Effect of a fishing closure on Chamelea gallina stocks along the Turkish coast
    (Cambridge Univ Press, 2023) Dagtekin, Murat; Dalgic, Goktug; Erbay, Murat; Akpinar, Ilkay Ozcan; Aydin, Mehmet; Ozdemir, Süleyman; Karayucel, Sedat
    The striped venus clam Chamelea gallina (SVE), plays an important role as an infaunal filter-feeder in the ecosystem, besides an important economic role in the Black Sea coasts of Turkey. It is caught using hydraulic dredge boats, then processed, and the final product (frozen meat) is exported to EU countries. SVE fishing requires a special licence and regulations. Also, SVE beds were closed to fisheries for the recovery of stocks for 2 years. In the study, SVE beds were investigated during the closed season over two years to assess stock density. Additionally, the number of macrobenthic species that share the same habitat as the SVE was determined. The sampling area was divided into five sub-areas and four strata by depth and then stratified random sampling was applied to collect data. In 2011, SVE stock sizes in the sub-areas were 11,723.58 +/- 5167.262 tons (Cide), 35,082.94 +/- 27,510.95 tons (Inebolu), 10,077.05 +/- 4970.68 tons (Turkeli), 3304.36 +/- 3215.1 tons (Ayancik) and 1431.3 +/- 1703.5 tons (Sarikum). In 2012, these estimated stocks were 13,820.41 +/- 6977.86 tons, 34,841.94 +/- 14,623.71 tons, 8148.27 +/- 5006.74 tons, 3420.72 +/- 3093.67 tons and 2023.74 +/- 2832.63 tons, respectively. However, the estimated SVE total biomass did not change significantly during the period when the fields were closed (P > 0.05). The results indicate that length-weight relationship parameters varied of b from 2.9011-2.9072 in two years. Shell damage during fishing, environmental factors, food competition and consumption by the main predator all have a significant impact on stock densities, and changes occurring in these conditions should be considered in fisheries management.
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    Length-weight relationships of 28 fish species caught from demersal trawl survey in the Middle Black Sea, Turkey
    (Tubitak Scientific & Technological Research Council Turkey, 2022) Dagtekin, Murat; Genc, Yasar; Kasapoglu, Nazli; Erik, Gokhan; Misir, Devrim Selim; Ilhan, Salih; Ok, Meltem
    This study provides updated the length-weight relationships and Fulton's condition factor of 28 fish species belonging to 23 families from the Black Sea. Samples were collected along the depths between 0-100 meters by demersal trawl surveys conducted seasonally from May 2017 to September 2019. A total of 83,885 specimens were collected. The length-weight relationships and Fulton's condition factor, minimum, maximum and mean lengths, total weights, descriptive statistics, and growth type were provided for all the species. The results indicate that LWR parameters of b varied from 2.2039 to 3.737 and Fulton's condition factor varied between 0.004 and 1.18. These findings could be useful for monitoring and management of sustainable fisheries and habitat health.
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    Population abundance and growth parameters of an exotic bivalve species, Anadara kagoshimensis, in the Southwestern Black Sea
    (Tubitak Scientific & Technological Research Council Turkey, 2023) Dagtekin, Murat; Dalgic, Goktug; Erbay, Murat; Akpinar, Ilkay Ozcan; Aydin, Mehmet; Ozdemir, Suleyman; Cebeci, Ayse
    Blood cockle (Anadara kagoshimensis ) is an Indo-Pacific species that later entered the Black Sea. The abundance of A. kagoshimensis, which is not subjected to commercial fishing, is important in terms of food competition with other bivalvia species. Baby clam (Chamelea gallina) together with the A. kagoshimensis are dominant bivalve species found in the sandy and muddy areas off the coastal waters of the Black Sea. In this study, specimens of A. kagoshimensis have been recognized by morphological analysis and also confirmed by molecular characterization. Furthermore, the abundance and growth parameters of A. kagoshimensis were investigated in the Southwestern Black Sea. Blood cockles were sampled between February 2011 and December 2012, seasonally. According to the Von Bertalanffy Growth Parameters (VBGP) the results were L infinity = 81.96 mm, K = 0.32 year-1, t0 = -0.22 year, and nonseasonal L infinity = 84.32 mm, K = 0.31 year-1, t0 = -0.21, WP = 0.65, ts = 0.15. The growth pattern showed the slope [b] = 2.96-3.01 in 2011 and 2012. The stock size was estimated according to two different years in 5 different subareas (Cide, Inebolu, Turkeli, Ayancik, and Sarikum) and by 4 different strata (0-5 m, 5-10 m, 10-15 m, and 15-20 m). Considering subareas, the A. kagoshimensis population in all subareas increased significantly in a single year. Compared to other regions, Inebolu was the main highly distributed area of the A. kagoshimensis, and also the estimated stock size was the highest in the region. Due to food competition with other commercial species (mainly Chamelea gallina) A. kagoshimensis is an ecology important species for the Southern Black Sea habitats. It is aimed to make contributions to Good Environmental Status (GES) and fisheries management in the region.