Size selection by diamond- and square-mesh codends in multi-species Mediterranean demersal trawl fisheries

Sala, Antonello; Lucchetti, Alessandro; Piccinetti, Corrado; Ferretti, Mário

doi:10.1016/j.fishres.2008.02.003

Cited by 93 publications

(111 citation statements)

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“…The studies carried out to increase the selectivity of bottom trawl net in the Mediterranean Sea showed that comparing to diamond-mesh codend, square-mesh codend, or panels give more chance individuals that have round shaped body to escape (Sala et al 2008. The same situation has been observed in Atlantic stargazer species that has round-shaped body form for this study and this codend was found successful for Atlantic stargazer species to escape.…”

Section: Discussionsupporting

confidence: 77%

“…The studies carried out to increase the selectivity of bottom trawl net in the Mediterranean Sea showed that square-mesh codend or panels give more chance to juveniles of most species to escape when compared with diamond-mesh codends (Sala et al 2008, Ateş et al 2010, Tokaç et al 2010. Underwater observations carried out by Robertson and Stewart (1988) for bottom trawl codends showed that the mesh has a tendency to close, depending upon increasing catch amount in diamond-mesh codend but in squaremesh codend, the mesh stayed open during the tow.…”

Section: Introductionmentioning

confidence: 99%

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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.

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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.

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Section: Discussionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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.

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“…Liggins et al, 1996;Kennelly et al, 1998;Sala et al, 2008) fish that comprise bycatches are usually quite small (< 20 cm long) and often juveniles. Seabob shrimp is a smaller species of penaeid (usually < 10 cm long) and, as bycatch fish species have a similar size it may be possible to reduce more effectively bycatches by a behavioural separating mechanism.…”

Section: Discussionmentioning

confidence: 99%

Relative efficiency of square mesh codends in an artisanal

Silva¹,

Dias²,

Cattani³

et al. 2012

lajar

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ABSTRACT. The relative efficiency of two square-mesh codend designs with the same circumference (~2 m) but different mesh sizes and materials (32 mm polyethylene-PE and 30 mm polyamide-PA) was tested in an artisanal shrimp trawl fishery in Paraná, southern Brazil. The two square-mesh codends were hauled alternately with a 26 mm diamond-shaped mesh codend (control) in a twin gear configuration. Although not significant, the mean numbers of total bycatch were reduced by 16.6 and 10.0% with the 32 and 30 mm square-mesh codends, respectively. The results indicate significant improvement in size selectivity for some species (Xiphopenaeus kroyeri and Stellifer rastrifer). The operational changes tested can be a suitable technical solution for reducing the capture of immature organisms in the shrimp trawl fishery in Paraná, Brazil.

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“…Studies have proved that the conventional diamond mesh codend selectivity is rather poor for many commercially important species in the Mediterranean (Özbilgin and Tosunoğlu, 2003;Tokac et al, 2004Tokac et al, , 2010Özbilgin et al, 2005, 2012, 2015Guijarro and Massuti 2006;Ordines et al, 2006;Bahamon et al, 2006;Luchetti, 2008;Sala et al, 2008;Aydın and Tosunoğlu, 2010;Sala and Luchetti, 2010;Aydın et al, 2011). Thus, researchers have suggested for improving selectivity using larger mesh size in the codend for reducing discards of the Mediterranean demersal trawl fleet (GFCM, 2007).…”

Section: Introductionmentioning

confidence: 99%

Untitled

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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Size selection by diamond- and square-mesh codends in multi-species Mediterranean demersal trawl fisheries

Cited by 93 publications

References 17 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

Relative efficiency of square mesh codends in an artisanal

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