Square mesh panels in North Sea demersal trawls: Separate estimates of panel and cod-end selectivity

O’Neill, Fiona; Kynoch, R.J.; Fryer, R. J.

doi:10.1016/j.fishres.2005.12.012

Cited by 44 publications

(39 citation statements)

References 13 publications

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“…Thus, the model applied by Zuur et al (2001), O'Neill et al (2006), and Alzorriz et al (2016) would probably not be sufficiently flexible to describe the size-dependent release efficiency in the square mesh section for all of our cases. Furthermore, we could not decide beforehand on a specific model structure for each of the individual cases.…”

Section: Collection Of Release Efficiency Data and Underwater Recordingsmentioning

confidence: 99%

“…For the fish contacting the meshes, the probability that they subsequently escape by passing or squeezing themselves through a mesh is quantified by a logistic size selection curve. Examples for using this modelling approach for studying size selection of square mesh panels in trawls include Zuur et al (2001), O'Neill et al (2006), and Alzorriz et al (2016). A limitation of this modelling approach is that it assumes the contact probability to be the same for all sizes of fish that would be able to pass or squeeze themselves through the meshes.…”

Section: Collection Of Release Efficiency Data and Underwater Recordingsmentioning

confidence: 99%

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Improving release efficiency of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery by stimulating escape behaviour

Grimaldo

Sistiaga

Herrmann

et al. 2018

Can. J. Fish. Aquat. Sci.

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Abstract:We tested the ability of stimulators to improve the release efficiency of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) through the meshes of a square mesh section installed in a trawl. The section was tested in three different configurations: without any stimulation device, with a mechanical stimulation device, and with LED light stimulation devices. We analysed and compared the behaviour of cod and haddock in all three configurations based on release results and underwater recordings. Parallel to the fishing trials, we carried out fall-through tests to determine the upper physical size limits for cod and haddock to be able to escape through the square meshes in the section. This enabled us to infer whether lack of release efficiency was due to fish behaviour or release potential of the square meshes in the section. The results showed that the escape behaviour of haddock can be triggered by mechanical stimulation. In contrast, cod did not react significantly to the presence of mechanical stimulators. LED light stimulation had some effect on the behaviour of haddock, but not on cod.Résumé : Nous avons vérifié la capacité de stimulateurs d'améliorer l'efficacité de la libération de morues (Gadus morhua) et d'aiglefins (Melanogrammus aeglefinus) par les mailles d'une section de mailles carrées installée dans un chalut. La section a été mise à l'essai selon trois configurations différentes, soit sans aucun instrument de stimulation, avec un instrument de stimulation mécanique et avec des instruments de stimulation à lumière DEL. Nous avons analysé et comparé le comportement des morues et des aiglefins dans les trois configurations à la lumière des résultats de libération et d'enregistrements sous l'eau. Parallèlement aux essais de pêche, nous avons mené des essais de passage par gravité afin de déterminer les limites supérieures des tailles auxquelles les morues et aiglefins peuvent s'évader par les mailles carrées dans la section. Cela nous a permis d'établir si l'absence d'une libération efficace était due au comportement des poissons ou au potentiel de libération des mailles carrées dans la section. Les résultats montrent que le comportement d'évasion des aiglefins peut être déclenché par une stimulation mécanique. Les morues, au contraire, n'ont pas présenté de réaction significative à la présence de stimulateurs mécaniques. La stimulation à la lumière DEL a eu un certain effet sur le comportement des aiglefins, mais pas sur celui des morues. [Traduit par la Rédaction]

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Section: Collection Of Release Efficiency Data and Underwater Recordingsmentioning

confidence: 99%

Section: Collection Of Release Efficiency Data and Underwater Recordingsmentioning

confidence: 99%

Improving release efficiency of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery by stimulating escape behaviour

Grimaldo

Sistiaga

Herrmann

et al. 2018

Can. J. Fish. Aquat. Sci.

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“…However, others have obtained the opposite result (O'Neill & Kynoch, 1996;Dahm et al, 2002), while emphasising that selectivity tends to decrease when the catch size is very high. On the other hand, the studies of Madsen et al (1998), O'Neill et al (2006) and Grimaldo et al (2008) yielded inconclusive results or found only a weak effect of the catch variable.…”

Section: Discussionmentioning

confidence: 98%

The effects of subsampling and between haul variation on the size selectivity estimation of Chilean hake (Merluccius gayi gayi)

Queirolo

Ahumada

Hurtado

et al. 2012

lajar

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ABSTRACT. Using the data collected in a size selectivity experiment on Chilean hake (Merluccius gayi gayi) carried out in 2000, the selectivity parameters for four codend mesh sizes (100, 110, 130, and 140 mm of mesh size opening) were estimated and modelled by the SELECT model. These analyses included considerations of the sampling proportions of the catch in the codend and cover. Furthermore, the analyses took into account between-haul variation. The l 50 values were 30.8, 29.9, 30.0, and 41.2 cm of total length, respectively, values lower than the estimates obtained from previous studies. The contribution of explanatory variables to the selectivity model was also tested in order to determine the role of mesh size, catch size (in number), and towing speed. Increases in catch size and in towing speed were accompanied by decreases in the l 50 estimates. These results demonstrate how incorporation of subsampling effect and explanatory variables to model between-haul variation can improve selectivity estimates and management of a valuable resource. Keywords: size selectivity, mesh size, subsampling effect, between-haul variation, Merluccius gayi gayi, Chile.Los efectos de submuestreo y variación entre lances en la estimación de la selectividad a la talla de la merluza común (Merluccius gayi gayi)RESUMEN. Usando los datos recolectados en un experimento de selectividad a la talla de merluza común (Merluccius gayi gayi) realizado en el año 2000, se estimaron y modelaron los parámetros de selectividad para copos de cuatro tamaños de malla (100, 110, 130 y 140 mm de tamaño de malla interno) mediante el modelo SELECT. Los análisis incluyeron consideraciones de las proporciones de muestreo de la captura en el copo y en el cubrecopo. Además, los análisis tuvieron en cuenta la variación entre lances. Los valores de l 50 fueron 30,8; 29,9; 30,0 y 41,2 cm longitud total respectivamente, valores menores que los obtenidos en estudios previos. Se probó también la contribución de variables explicatorias al modelo de selectividad, para determinar el aporte del tamaño de malla, el volumen de captura (en número) y la velocidad de arrastre. Los incrementos en el volumen de captura y en la velocidad de arrastre produjeron una disminución en los estimados de l 50 . Estos resultados demuestran cómo, a partir de la incorporación del efecto de submuestreo y de variables explicatorias al modelo con variación entre lances, es posible mejorar los estimados de selectividad y manejar un valioso recurso. Palabras clave: selectividad a la talla, tamaño de malla, efecto de submuestreo, variación entre lances, Merluccius gayi gayi, Chile.

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“…The combination of contact selection and contact probability was termed the available selection model by Millar and Fryer [12]. This available selection model has been used to determine the separation of the grid separator [13,14], the square mesh bycatch reduction window [15,16], selectivity for the cod-end when the mesh of the cod-end is clogged by the catch [17], and the effect of the dredge tooth spacing on selectivity for bivalves [18,19].…”

Section: Introductionmentioning

confidence: 99%

Modeling of available size selectivity of the SURF-BRD for shrimp beam trawl

Kajikawa

Tokai

2013

Fish Sci

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The System of Unwants Ramp-way FilteredBycatch Reduction Device (SURF-BRD) was developed to reduce shrimp bycatch in a shrimp beam trawl. It consists of a pair of rectangular net panels, namely, the front panel (FP) and rear panel (RP), and two fish escape vents. In this study, numerical models for expressing available selection by the SURF-BRD were proposed and assessed in several fishing experiments conducted using two types of the BRD: a prototype and an improved type with the BRD attached at a higher point on the side-nets . Contact probability and selectivity parameters of the FP and the RP for four major species were estimated for each BRD type. The improved type with the higher BRD showed a larger contact probability for the FP. Size selectivity of the FP and RP for two species (cinnamon flounder and spotted swimming crab) was almost equivalent to the mesh selectivity of the net panel, but that for lizard fish seemed to depend not on mesh size of the FP but on the swimming behavior of the fish. These results suggest that the smaller mesh size of the RP would be helpful for releasing more fish of smaller size and to exclude more spotted swimming crab, which hinder ondeck sorting by fishermen.

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Square mesh panels in North Sea demersal trawls: Separate estimates of panel and cod-end selectivity

Cited by 44 publications

References 13 publications

Improving release efficiency of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery by stimulating escape behaviour

Improving release efficiency of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery by stimulating escape behaviour

The effects of subsampling and between haul variation on the size selectivity estimation of Chilean hake (Merluccius gayi gayi)

Modeling of available size selectivity of the SURF-BRD for shrimp beam trawl

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