Abstract:In this study, structural characteristics of towed fishing gears (bottom and beam trawls) used on the coasts of Samsun were investigated as part of EU-FP7 BENTHIS project. Data for bottom and beam trawl (net, otter board, beam etc.) were obtained in situ investigations and survey studies with fishermen face to face. The numbers of total and active trawl vessel in this area were determined after that these vessels were classified according to size categories. Stratified subsampling for representing the main fleet is taken from that worked during 2011/12 and 2012/13 fishing season. General characteristics of the bottom trawl nets are in two configurations and cutting shape, whereas the otter boards are rectangular shaped. In these nets the number of meshes in fishing circle is changed between 450 and 975, 650 and 750 meshes are the most preferred (%38). All of the bottom trawls (40-80 m depths) are towed with a stern trawler, the engine powers of these vessels are changed between 99 and 1067 kW and 57% of these vessels are between 200 and 500 kW. Rapa whelk (Rapana venosa) fishery is also heavily done with beam trawls on the coasts of Samsun (5-30 m). Some technical differences were observed between the functional designs of the beam trawls used in different locations. While 77% of the beam trawls with engine power between 9.6 and 285 kW were used pair gears on deck, the rest was performed with a single gear. The length and weight of the beam trawls changed 2-3.2 m and 22-61 kg, respectively. As a result, a number of modifications for both fishing gears have been made for more catch so far. There is a need to reveal the changes, monitoring and known to the structural characteristics of these gears for ecosystem approach fisheries. Keywords: Black Sea, Samsun, bottom trawl, beam trawl, Rapa whelk.Özet Bu çalışmada Samsun kıyılarında kullanılan sürükleme av araçlarının (dip trolü ve algarna) yapısal özellikleri EU-FP7 BENTHIS adlı proje kapsamında araştırılmıştır. Dip trolü ve algarnaya (ağlar, kapılar, kiriş vs.) ait veriler balıkçılar ile yapılan yüz yüze görüşmelerde ve yerinde incelemelerde elde edilmiştir. Samsun kıyılarında kullanılan toplam ve aktif trol tekne sayısı belirlendikten sonra bu gemiler boy gruplarına göre sınıflandırılmıştır. Ana kitleyi temsil eden tabakalı alt örnekleme 2011/12 ve 2012/2013 balıkçılık sezonu süresince çalışan ana filodan seçilmiştir. Dip trol ağları yapısal olarak iki görünümlü ve kesimli, kapılar ise dikdörtgen şeklindedir. 450 ve 975 göz büyüklüğünde değişen bu ağlardan 650 ve 750 gözler en fazla (%38) tercih edilenlerdir. Dip trollerinin tamamı (40-80 m derinlik) tek tekne ile çekilmekte, tekne motor güçleri 99 ile 1067 kW arasında değişmekte olup %57'si 200 ile 500 kW arasındadır. Samsun kıyılarında (5-30 m) ayrıca algarnalar ile yoğun olarak deniz salyangozu (Rapana venosa) avcılığı da yapılmaktadır. Farklı alanlarda kullanılan algarnaların tasarımları arasında bazı teknik farklılıklar gözlemlenmiştir. 9,6 ve 285 kW arasındaki motor gücüne sahip alagarna tekneleri...
M ore than half of the landing (70%) of Red mullet (Mullus barbatus) in Turkey is provided from the Black Sea, which is almost all (96%) with bottom trawls. The effect of demersal trawl codend mesh shape and size on the s electivity of Red mullet in the Black Sea was investigated. Selectivity trials were conducted in August 2014 on a commercial trawl boat with conventional (40D), 36 and 40 mm square mesh (36S and 40S) and turned mesh codends (40T90). Data were collected using the covered codend method with a total of 21 valid hauls and selection parameters were obtained by fitting a logistic equation using maximum likelihood method. The L 50 value was found to be very low at 9.79 cm in the 40D trawl codend, while the L 50 value of 40S (11.89 cm) and 36S (10.59 cm) codends was obtained 21.5% and 8.2% better compared to the 40D, respectively. According to the traditional trawl codend, a L 50 value increase of 5.1% was observed in 40T90 (10.29 cm). Although all these values are below the M inimum Landing Size of the species, changes to the traditional mesh, especially in the shape of the mesh, can lead to significant improvements in size selectivity.
A large part of the total whiting (Merlangius merlangus euxinus) fishing in the Black Sea is carried out with the traditional bottom trawl nets along the coast of Turkey. Diamond mesh shape with 40 mm mesh size (40D) has been used in the codends of these trawls. In this study, the traditional trawl codend (40D) and square-mesh codend with different size (36S and 40S) were compared for whiting size selectivity in August 2014. Selectivity data were collected by using a covered codend method and analysed taking between haul variations in to account. The selectivity parameters were estimated by using CC2000 software. Results showed that commercially used 40D trawl codend is not selective enough to release immature of whiting. However, the net change in square mesh (36S and 40S) instead of a diamond-shaped (40D) mesh significantly improved the mesh selectivity for whiting. The 40S trawl codend is even higher than the first maturity size (LM50) with a length at fifty percent retention (L50) of 15.74 cm. In conclusion all square mesh codends with different mesh size tested here supplied appropriate selection considering minimum landing size (MLS) of whiting.
In this study, construction and efficiency of artisanal fishing gears used in Karina and Akköy (Arapça, Karaca, Bölme and Kabahayıt) coastal lagoons were investigated. Data were gathered with face to face interviews in the years of 2013-2014 field surveys. According to results, the vast majority of fish in Karina and Akköy coastal lagoons were caught by artisanal fishing gears (trammel net, fyke net and longline). 90% and 50% of the total production are obtained with these gears in Karina and Akköy lagoons, respectively. While Karina lagoon is being managed by 240 members of S.S. Doğanbey-Tuzburgazı Fisheries Cooperative, Akköy is administrated by a private company. Five boats are working with income portion in Akköy lagoon, as about 100 members with 60 boats sustains fishing operations in Karina. To determine of structures and effectiveness of artisanal fishing gears used in both lagoons, contribute to size selectivity and maximum sustainable yields for species based on fisheries.
European pilchard Sardina pilchardus (Walbaum, 1792) is one of the most dominant small pelagic landed by purse seine in Turkey as well as Mediterranean. In this study, we aimed to identify relationships between the seasonally adjusted CPUE and changes of the sea surface temperature (SST), fishing area, moon phase, and light used in the purse seine fishery to understand the impact of changes on the CPUE of pelagic fishes, especially S. pilchardus, by a total of 214 operations in Izmir Bay, Aegean Sea. The effect of the parameters on the Sardine CPUE, expressed in terms of kg (haul day)–1, was examined by means of the Generalized Additive Modelling (GAMs) techniques. The CPUE values for S. pilchardus were between 0 – 16 800 kg (haul day)–1 and the mean CPUE was 1 844.3±176.6 kg (haul day)–1 . The smallest median was 441 kg (haul day)–1 for full moon and the differences between the CPUE values of lunar phases were statistically significant (p<0.05). Furthermore, there is a linear relationship between CPUE and SST. In conclusion, the CPUE varied under hydrographic variables mostly SST for sardine purse seine fishery in the Aegean Sea.
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