A comparison of size selection of haddock and whiting by square and diamond mesh codends

Robertson, Julie; Stewart, Peter A.

doi:10.1093/icesjms/44.2.148

Cited by 104 publications

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“…Veličina i oblik oka na saki su glavni faktori koji utiču na selektivnost ribarskog alata jer npr. oka u obliku romba (diamond-shaped mesh) se tokom povlačenja mreže rastegnu i zatvore kad se saka puni ulovom, što smanjuje selektivnost u poređenju sa okom u obliku kvadrata (square mesh), koja za vrijeme vučenja mreže ostaju otvorena (Robertson & Stewart, 1988). Iz tog razloga su Generalna Komisija za Ribarstvo Mediterana (GFCM)…”

Section: Relativni Odnos Prinosa Po Prinoviunclassified

Biology of the deep water pink shrimp Parapenaeus longirostris (Lucas, 1846) (Crustacea, Decapoda) on the Montenegrin shelf

Marković¹

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Section: Relativni Odnos Prinosa Po Prinoviunclassified

Biology of the deep water pink shrimp Parapenaeus longirostris (Lucas, 1846) (Crustacea, Decapoda) on the Montenegrin shelf

Marković¹

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“…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. Fonteyne and Polet (2002) showed that square-mesh windows inserted in the belly just in front of the codend significantly reduced the by-catch amount of the majority of benthic species in the flatfish beam trawl fisheries.…”

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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“…In fact, through the regulation of size at first capture, improvements in gear selectivity are expected to reduce the capture of juveniles and increase the yield per recruit of targeted species, while reducing the total amount of discards (Armstrong et al 1990, MacLennan 1992 In bottom trawl fisheries, the main factors influencing gear selectivity are the codend mesh size and shape (Robertson andStewart 1988, Reeves et al 1992). In particular, a diamond-shaped mesh displays a tendency to stretch and close under tension, reducing its effective selectivity as the codend fills with the catch.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, a diamond-shaped mesh displays a tendency to stretch and close under tension, reducing its effective selectivity as the codend fills with the catch. Conversely, a square-shaped mesh tends to stay open during a tow, displaying an overall higher selectivity for most species than a diamond-shaped mesh of the same nominal size (Robertson andStewart 1988, Sala et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Improving codend selectivity in the fishery of the deep-sea red shrimp <em>Aristeus antennatus</em> in the northwestern Mediterranean Sea

2017

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Summary:The deep-sea red shrimp Aristeus antennatus is one of the most valuable demersal resources in Catalonia (northeast Spain), and Palamós is the most important harbour for this fishery in the area. Here, a management plan published in 2013 established the use of a 40-mm square-mesh codend (40s), replacing the previously used 50-mm diamond mesh codend (50d). The objective was to decrease the amount of juveniles in the catches, but the regulation did not bring the expected results. In this study, we measured and compared the selectivity of the 40s and the 50d in this fishery. In addition, we experimented with the use of a 50-mm square-mesh codend (50s). According to our results, the 40s had a lower 50% selection length (L 50 ) than the 50d, while the 50s had a substantially higher L 50 than the other two. A transition analysis showed an increase in yield per recruit after the second year from a hypothetical implementation of the 50s. Our conclusion is that the 40s does not have a higher selectivity than the 50d, which (at least partially) explains the failure to reach the management objective in Palamós. Conversely, the use of a 50s would significantly benefit the fishery, increasing gear selectivity and yield per recruit.Keywords: codend selectivity; Aristeus antennatus; mesh configuration; yield per recruit; transition analysis; bottom trawling; NW Mediterranean Sea.Mejora de la selectividad del copo en la pesquería de arrastre de la gamba roja, Aristeus antennatus, en el Mediterrá-neo noroccidental Resumen: La gamba roja, Aristeus antennatus, es uno de los recursos demersales más valorados en Cataluña (noreste de España). Palamós es el puerto pesquero más importante para esta pesquería en la región. Una orden ministerial regulatoria y específica para este puerto, publicada en 2013, estableció la utilización de un copo de malla cuadrada con abertura mínima de 40 mm (40s), reemplazando el copo de malla romboidal de 50 mm (50d) utilizado hasta la fecha. El objetivo era disminuir la cantidad de juveniles en la captura, pero la regulación no consiguió los resultados esperados. En el presente estudio, se midió y comparó la selectividad del copo de 50d y 40s en esta pesquería. Además, se experimentó el uso de una malla cuadrada de 50 mm (50s). Los resultados mostraron que el copo de 40s presentaba una talla de retención del 50% (L 50 ) menor comparado con el copo de 50d, mientras que el de 50s tenía una L 50 considerablemente mayor que los demás copos. El análisis de transición mostró un aumento del rendimiento por recluta (Y/R) después del segundo año desde la hipotética implementación del copo de 50s. Nuestra conclusión es que el copo de 40s no tiene una selectividad mayor que el copo de 50d, explicando (por lo menos en parte) la falta de consecución de los objetivos de gestión en la pesquería de gamba de Palamós. En cambio, el copo de 50s mejoraría significativamente a la pesquería, aumentando la selectividad del arte y el Y/R.Palabras clave: selectividad del copo; Aristeus antennatus; configuración de la mall...

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A comparison of size selection of haddock and whiting by square and diamond mesh codends

Cited by 104 publications

References 0 publications

Biology of the deep water pink shrimp Parapenaeus longirostris (Lucas, 1846) (Crustacea, Decapoda) on the Montenegrin shelf

Biology of the deep water pink shrimp Parapenaeus longirostris (Lucas, 1846) (Crustacea, Decapoda) on the Montenegrin shelf

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

Improving codend selectivity in the fishery of the deep-sea red shrimp <em>Aristeus antennatus</em> in the northwestern Mediterranean Sea

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