Selectivity of commercial compared to larger mesh and square mesh trawl codends for four fish species in the Aegean Sea

Özbilgin, Hüseyin; Tokaç, Adnan; Kaykaç, Hakan

doi:10.1111/j.1439-0426.2011.01916.x

Cited by 20 publications

(23 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Considering the body form of flatfishes caught in this study, it is understood that square-mesh codends are not proper for flatfish species to escape. Similar findings for square-mesh codends had been reported in the studies that were carried out in the Mediterranean Sea about bottom trawl net selectivity (Özbilgin et al 2012(Özbilgin et al , Eryaşar 2017. Özbilgin et al (2012) reported that square-mesh codend is not a definitive solution to the poor bottom trawl net selection, especially for many flat and high-bodied fish species.…”

Section: Discussionsupporting

confidence: 76%

Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Eryaşar¹

2018

Acta Ichthyol. Piscat.

View full text Add to dashboard Cite

Eryaşar A.R. 2018. Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa. Acta Ichthyol. Piscat. 48 (2): 173-181.Background. The beam trawl fisheries of veined rapa whelk, Rapana venosa (Valenciennes, 1846), cause small benthic organisms to be captured and also damage the other species living on the seafloor. To solve this problem, a proper modification that minimise the by-catch should be designed and put into practice. This study aims to compare 72 mm commercial diamond-mesh codend with 72 mm square-mesh codend to reduce the benthic bycatch in this fishery. Materials and methods. Totally 15 hauls were carried out in south-eastern Black Sea Region within 10-14 August 2017. A commercial diamond-mesh and square-mesh beam trawls were towed simultaneously behind a commercial fishing vessel to compare the by-catch compositions. Paired t-test was used to compare the catch amount of two codends based on species. GLMM (Generalised Linear Mixed Models) was used to compare the length of captured veined rapa whelk, mussel, and crab species.Results. There was a 77-percentage-point reduction in the mean number of the captured individuals as by-catch in square-mesh codend when compared with commercial diamond-mesh codend and this difference was found statistically significant (P < 0.05). A total of 17 species was captured as by-catch in both codends. Comparing to diamond-mesh codend, the catch amount of the 13 by-catch species had decreased in square-mesh codend.Conclusions. In conclusion, the square-mesh codend was found successful in decreasing the by-catch amount of many benthic species except for flatfish species and large crabs. In addition to this, the veined rapa whelk amount fell by half and this means a 25-percentage-point profit decrease for fishermen.

show abstract

Section: Discussionsupporting

confidence: 76%

Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Eryaşar¹

2018

Acta Ichthyol. Piscat.

View full text Add to dashboard Cite

show abstract

“…Previous studies from the Mediterranean have shown that increasing mesh size in the trawl codends improves the L50 values (Özbilgin et al, 2012;Tokaç et al, 2014). In this study, It was determined that increasing mesh size (from 44 to 50 mm) would lead to in the range of 7 to 17% increase in L50 values for three species except Atlantic horse mackerel.…”

Section: Discussionmentioning

confidence: 82%

Untitled

Dereli̇¹,

Aydın²

2016

Turk. J. Fish. Aquat. Sci.

View full text Add to dashboard Cite

This paper compares the selectivity of 44 mm diamond mesh codend used in commercial fisheries (D44) and alternative codends 50 mm diamond (D50), a 40 mm square (S40) and a 40 mm 90° turned mesh (T40) for red mullet Mullus barbatus, European hake Merluccius merluccius, Morocco dentex Dentex maroccanus, Atlantic horse mackerel Trachurus trachurus in the Eastern Mediterranean demersal trawl fishery. Sea trials were carried out in the international waters between Turkey and Greece (Aegean Sea), with commercial trawler. Selectivity data were collected using the covered codend method and analysed by means of a logistic equation with the maximum likelihood method. Mean selection curves were estimated and compared using the between-haul variations model. The mean 50% retention total length values (L50) of D44, D50, S40 and T40 codends are 11.1, 12.9, 12.9 and 13.6 cm for red mullet, 12.3, 14.4 and 14.3 cm for hake, 10.0, 10.7, 10.3 and 8.4 cm for Morocco dentex and 16.2, 14.2, 15.3 and 17.1 cm for mackerel, respectively. The results show that there are statistically differences between L50 values of four codends for only red mullet. S40 and T40 codends improve the selectivity of red mullet when considering commercially D44 codend.Keywords: Codend selectivity, mesh shape, Eastern Mediterranean, demersal trawl. Doğu Akdeniz Dip Trol Balıkçılığında Dört Tür İçin Ticari ve Alternatif Torbaların Seçiciliği ÖzetBu çalışmada Doğu Akdeniz demersal trol balıkçılığında ticari olarak kullanılan 44 mm baklava gözlü torba (D44) ile 50 mm baklava gözlü (50D), 40 mm kare gözlü (S40) ve 40 mm 90° döndürülmüş (T40) alternatif torbaların barbunya Mullus barbatus, bakalyaro Merluccius merluccius, Fas mercanı Dentex maroccanus ve istavrit Trachurus trachurus için seçicilikleri karşılaştırılmıştır. Denemeler ticari trol teknesi ile Türkiye ile Yunanistan arasında kalan uluslararası sularda (Ege Denizi) yürütülmüştür. Seçicilik verisi çemberli örtü torba tekniği ile toplanmış ve lojistik eşitliğin maksimum olabilirlik yöntemi ile analiz edilmiştir. Ortalama seçicilik eğrileri, çekimler arası varyasyon modeli kullanılarak tahmin edilmiş ve karşılaştırılmıştır. D44, D50, S40 ve T40 torbalarındaki ortalama % 50 yakalama boyları (L50) barbunya için sırasıyla 11,1; 12,9; 12,9 ve 13,6 cm, bakalyaro için 12,3; 14,4 ve 14,3 cm, Fas mercanı için 10,0; 10,7; 10,3 ve 8,4 cm ve istavrit için 16,2; 14,2; 15,3 ve 17,1 cm olarak tespit edilmiştir. Bulgular, dört torbanın L50 değerleri arasında istatistiksel farkın sadece barbunya için bulunduğunu göstermektedir. S40 ve T40 torbalar, ticari olarak kullanılan D44 torbaya göre barbunyanın seçiciliğini geliştirmiştir.Anahtar Kelimeler: Torba seçiciliği, göz şekli, Doğu Akdeniz, demersal trol.

show abstract

“…On the other hand, Ragonese and Bianchini (2006) suggested that the range of 50.2-70.3 mm is a "biologically-sound mesh size" referring to the size at 50% maturity ranges of 20-22 mm for rose shrimp for Italian waters. Guijarro and Massutí (2006) (Aydın et al 2010); and 16.9 cm (42.9 mm) (Ozbilgin et al 2012). On the other hand, a T90 L 50 value determined in the course of the presently reported study (12.2 cm) is comparable to the previously reported value of 12.5 cm (Tokac et al 2010, Ozbilgin et al 2012, determined for diamond-mesh codend of 42.4 and 42.2 mm, respectively.…”

Section: Discussionmentioning

confidence: 97%

Selectivity of 40 mm square- and 90º turned-mesh codend for the deepwater rose shrimp, Parapenaeus longirostris (Crustacea), and greater forkbeard, Phycis blennoides (Actinopterygii: Gadiformes: Phycidae), in the eastern Mediterranean

Aydın¹

2015

Acta Ichthyol. Piscat.

View full text Add to dashboard Cite

Aydın C., Tokaç A. 2015. Selectivity of 40 mm square-and 90º turned-mesh codend for the deepwater rose shrimp, Parapenaeus longirostris (Crustacea), and greater forkbeard, Phycis blennoides (Actinopterygii: Gadiformes: Phycidae), in the eastern Mediterranean. Acta Ichthyol. Piscat. 45 (4): 353-362.Background. Bottom trawling is an important fi shing technique for catching demersal fi sh, and selectivity is one of the most important tools for fi shery management. This study aimed to determine the selectivity of 40 mm square-(40S) and 90º turned-mesh (40T90) codend for the deepwater rose shrimp, Parapenaeus longirostris, and greater forkbeard, Phycis blennoides (Brünnich, 1768). Material and methods.Fishing experiments were conducted on the international waters of the Aegean Sea by using a commercial vessel between 24 August and 13 September 2012. The hooped covered codend technique was employed for the estimated codend selectivity. The selectivity parameters were estimated by using CC 2000 software.Results. Nineteen successful hauls, 11 with 40S, and 8 with 40T90 codends, were performed. The mean L 50 values (50% retention length) of 40S and 40T90 were found to be a 15.5 ± 0.1 mm and 14.8 ± 0.1 mm carapace lengths for the rose shrimp, and 15.3 ± 0.1 cm and 12.2 ± 0.1 cm total lengths for the greater forkbeard, respectively. Conclusion. In conclusion, 165 square meshes in a codend circumference with 40 mm mesh sizes provided higher L 50 values than the 40 mm turned meshes, and 330 meshes around the codend circumference. Halving the number of meshes in the codend with larger turned mesh and different modifi cations should be investigated for further studies in order to appropriate the L 50 values.

show abstract

Selectivity of commercial compared to larger mesh and square mesh trawl codends for four fish species in the Aegean Sea

Cited by 20 publications

References 35 publications

Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Effects of square-mesh codend on the benthic by-catch for the beam trawl fisheries of veined rapa whelk, Rapana venosa

Untitled

Selectivity of 40 mm square- and 90º turned-mesh codend for the deepwater rose shrimp, Parapenaeus longirostris (Crustacea), and greater forkbeard, Phycis blennoides (Actinopterygii: Gadiformes: Phycidae), in the eastern Mediterranean

Contact Info

Product

Resources

About