Effect of PA and PE material on codend selectivity in Turkish bottom trawl

Tokaç, Adnan; Özbilgin, Hüseyin; Tosunoğlu, Zafer

doi:10.1016/j.fishres.2003.10.001

Cited by 56 publications

(63 citation statements)

References 6 publications

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“…It was determined that various factors can affect the selectivity, such as, twine material (Tokaç et al, 2004) and thickness (Lowry and Robertson, 1996;Herrmann and O'Neill, 2006;Sala et al, 2007), codend circumference (Reeves et al, 1992;Broadhurst and Millar, 2009;Hermann et al, 2007;Graham et al, 2009;Wienbeck et al, 2011), towing speed (Dahm et al, 2002). Apart from these, total and codend catch, and species catch and haul durations which were evaluated in the present study affected L50 and SR values (Table 6).…”

Section: Discussionmentioning

confidence: 73%

“…Finally, T90 codend has been introduced as an alternative with EU Regulation no 2187/2005 for the Baltic Sea trawl fishery when targeting cod since 2006 (EC, 2005;Wienbeck and Dahm, 2006). Few studies conducted on selectivity properties with T90 codends not only in Turkish waters (Tokaç et al, 2004;Kaykaç et al, 2005;Deval and Özgen, 2012;Aydın and Tokaç, 2015) but also in Mediterranean Basin.…”

Section: Introductionmentioning

confidence: 99%

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Dereli̇¹,

Aydın²

2016

Turk. J. Fish. Aquat. Sci.

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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.

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Section: Discussionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Untitled

Dereli̇¹,

Aydın²

2016

Turk. J. Fish. Aquat. Sci.

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“…double 5 mm), the mesh size corresponding to the L 50 of the grid system would therefore likely be somewhat di erent. However, of the limited published data available, there is no evidence that SR is a ected by material and twine thickness (Kynoch et al, 1999;Tokaç et al, 2004). The conclusion (no evidence of sharper selection of grids than diamond mesh codend) should therefore also be valid for the comparison of the grid system with the 155 mm mesh codend, despite the di erences in material and twine thickness.…”

Section: Discussionmentioning

confidence: 95%

Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

et al. 2006

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Size selective grids were introduced into the Barents Sea demersal trawl shery in 1997. It was believed at the time that in comparison to standard diamond mesh codends, grids had better selective properties, i.e. narrower selection range. Few studies have directly compared the selective properties of the combined grid and codend with that of the codend only. In this study we describe two experiments carried out in 2002 and 2003, where we directly compared the properties of codend selectivity for cod (Gadus morhua ) with the combined selectivity of a Sort-V grid and a codend. In 2002 we used small-meshed covers, whereas the twin trawl method was used in 2003. In both experiments we compared the selectivity of a 135 mm codend only with that of a trawl tted with a 135 mm codend and a 55 mm grid, which is the mandatory con guration. In 2003 we also estimated the selectivity of a 155 mm diamond mesh codend, having an L 50 similar to that of the grid and 135 mm codend combination. The results presented no evidence that the grid and mesh combination had sharper size selection than codend meshes. The introduction of the mandatory use of grid in the shery in 1997 therefore only increased L 50 , and corresponded to a mesh size increase of around 20 mm. Mean selection length of the grid was inversely related to catch rates in the 2002 experiment when large catches were taken. Grid selection appeared less a ected by seasonal variations in degree of stomach fullness or condition than mesh selectivity. Other situations where grid selection might perform better than mesh selection are discussed.

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“…Minimum legal sizes are the most common tools used worldwide to manage recreational fisheries (Alós et al, 2009). While the size-selective nature of gear, such as trawls (Wileman et al, 1996;Tokaç et al, 2004) and gill nets (Kalaycı and Yeşilçiçek, 2012), are well known, there is still no clear consensus on the form of the size-selection curve for hooks on longlines (Czerwinski et al, 2010;Campbell et al, 2014). Especially in Turkey, there are few studies on hook selectivity and efficiency with respect to recreational fisheries.…”

Section: Introductionmentioning

confidence: 99%

Untitled

Ateşşahin¹,

Duman²,

Cılbız³

2015

Turk. J. Fish. Aquat. Sci.

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The aim of this study was to determine the relationship between spinner hook sizes (2, 3 and 4) and hook selectivity for Oncorhynchus mykiss (rainbow trout), a species important to recreational fisheries in Karakaya Dam Lake in Eastern Turkey.A total of 24 sampling trips were carried out twice per month by the same three anglers from May 2013 to April 2014. The SELECT method was used to determine the selectivity parameters. An analysis to determine the differences in the catch per unit effort (CPUE), yield per unit effort (YPUE) and condition factor values based on different hook sizes was conducted using one-way ANOVA. During the spinner hook-size experiments, we captured 202 Oncorhynchus mykiss, which ranged from 14.5 cm to 46.0 cm TL in length and weight 30.2 g to 1320.2 g. The mean lengths (±SE) of Oncorhynchus mykiss captured on the three spinner hook sizes were determined. The optimum lengths calculated by log-normal model were found to be 18.28, 27.41 and 36.55 cm for No 2, No 3 and No 4 hook sizes, respectively.

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Effect of PA and PE material on codend selectivity in Turkish bottom trawl

Cited by 56 publications

References 6 publications

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Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

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