Selectivity of diamond (PA) and square (PE) mesh codends for commercially important fish species in the Antalya Bay, eastern Mediterranean

Ateş, Celal; Deval, Mehmet Cengiz; Bök, T.; Tosunoğlu, Zafer

doi:10.1111/j.1439-0426.2010.01462.x

Cited by 21 publications

(15 citation statements)

References 16 publications

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“…In this fishery, when selectivity is achieved in only some species, sufficient selectivity is not possible for many other species due to differences in body shape, size and behaviors (Ateş et al, 2010). Skates and rays of all sizes are widely caught in multi-species fisheries and because of their body morphology are not able to escape from the cod end (Enever et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

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Saygu¹,

Deval²

2014

Turk. J. Fish. Aquat. Sci.

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Knowing post-release survival rates of fish escaping or being thrown back into the sea as discards is important for effective stock assessment. The aim of this study was to estimate the short-term discard survival rates of the two most abundant by-catch skate species (thornback skate: Raja clavata and brown skate: Raja miraletus) in the bottom trawl fisheries in Antalya Bay and to determine the factors affecting discard survival of skates. For the thornback skate the mean health score, the percentage with a health score 2 and percentage dead at time zero were 2.3, 91% and 2%, respectively. For brown skate, these values were 1.2, 43% and 26.5%, respectively. Considering the health score of these species, the fish length (P=0.001) and the tow duration (P=0.006) were significant parameters for the thornback skate, and the tow duration (P=0.046), the total length (P=0.044) and the catch amount (P=0.008) were found to be significant for brown skate. The mean survival time and the survival rate after 48 hours in tanks were 41 hours and 81% for thornback skate, and 15 hours and 21% for brown skate. The health condition of the individuals transferred to the tanks is an important reference point for their survival rates. Thornback and brown skates entering the tanks with a health score of 1 had a 44% and 9% chance of survival, respectively. On the other hand, skates entering the tanks with a health score of 2 or 3 had a 92% chance of survival for thornback skate and 49% for brown skate.

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Section: Discussionmentioning

confidence: 99%

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Saygu¹,

Deval²

2014

Turk. J. Fish. Aquat. Sci.

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“…Estimated selectivity parameters of individual and mean hauls (according to Fryer, 1991) LFM. L50 values of bogue estimated in the present study for all codend are slightly lower from found by Ateş et al (2010) 44 mm PA codend with 300 meshes around the circumferences as 14.2 cm from Antalya Bay. Ateş et al (2010) also presented that changing mesh configuration from diamond to square, L50 values was increase even decrease mesh size from 44 to 40 mm.…”

Section: Discussionmentioning

confidence: 40%

“…On the other hand, Eryaşar et al (2014) estimated L50 values as 6.81 cm and 7.56 cm from hand-woven 300 mesh and 150 mesh in circumference narrow slack knotted codend, respectively. When SRs were compared, the values for 40T1(2.3 cm), 44T1(3.5 cm) and 44T2 (3.0 cm) are close to those determined by Ateş et al (2010) as 3.0 and 2.1 for 44 mm diamond and 40 mm square mesh codend, respectively and Eryaşar et al (2014) as 3.1 and 3.5 cm with standard and narrowed codend, respectively.…”

Section: Discussionmentioning

confidence: 93%

“…However, there is very little information for bogue selectivity. Ateş, Deval, Bök, and Tosunoğlu (2010) present the 44 mm polyamide (PA) diamond mesh codend and 40 mm polyethylene (PE) square mesh codend. Eryaşar et al (2014) gave L50 values for standard nominal 44 mm PE mesh codend (300 meshes on its circumference) and narrowed (150 mesh) codends for the species.…”

Section: Introductionmentioning

confidence: 99%

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Ilkyaz¹,

Sensurat²,

Dereli̇³

et al. 2017

Turk. J. Fish. Aquat. Sci.

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This study investigated the selectivity of 90° turned meshes of 40 mm mesh size with 165 meshes around codend circumferences (40T1), 44 mm meshes size with 300 meshes around codend circumferences (44T1) and 44 mm mesh sizes with 150 meshes around codend circumferences (44T2). Experiments were carried out in the Kuşadası Bay of the Eastern Mediterranean, between 19 January and 29 March 2015 with commercial stern trawler. Selectivity data were collected using the covered codend method and analysed by means of a logistic equation with the maximum likelihood method. Individual hauls and mean selectivity parameter were estimated by using the CC2000 and EC-Modeller software, respectively. The mean 50% retention total length values (L50) and selection range (SR) were 12.7 cm and 2.3 cm for 40T1, 13.2 cm and 3.5 cm for 44T1 and 13.8 cm and 3.0 for 44T2, respectively. Significant differences were determined among the L50 values of the codends (between 40T1 and 44T2) (P<0.05). However, there are no statistical difference between the 40T1 and 44T1, 44T1 and 44T2 (P>0.05). On the other hand, L50 values of 40T1 and 44T1 are very close considered to the 13 cm length at first maturity size of the species.

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“…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%

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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Selectivity of diamond (PA) and square (PE) mesh codends for commercially important fish species in the Antalya Bay, eastern Mediterranean

Cited by 21 publications

References 16 publications

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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

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