Size selective performance of two flexible sorting grid designs in the Northeast Arctic cod ( Gadus morhua ) and haddock ( Melanogrammus aeglefinus ) fishery

Sistiaga, Manu Berrondo; Brinkhof, Jesse; Herrmann, Bent; Grimaldo, Eduardo; Langård, Lise; Lilleng, Dagfinn

doi:10.1016/j.fishres.2016.06.022

Cited by 39 publications

(36 citation statements)

References 18 publications

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“…No significant differences were found for cod, whereas the results for haddock only indicated an effect for the smaller individuals. Despite cod and haddock having different behavioural patterns in the aft part of a trawl (Engås et al 1998, Ferro et al 2007, Sistiaga et al 2016, somewhat like hake and blue whiting, the results in the present study showed no difference in the behavioural response of hake and blue whiting to LED lights.…”

Section: Discussioncontrasting

confidence: 77%

Release efficiency and selectivity of four different square mesh panel configurations in the Basque mixed bottom trawl fishery

et al. 2020

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Reduction of discards from the Basque mixed bottom trawl fishery is a challenge. To improve the selective properties of the gear used by the fleet and supplement codend size selection, a square mesh panel (SMP) installed in the upper panel of the trawl was introduced in 2006. However, recent studies have shown that the release efficiency of this SMP is low due to lack of contact between the fish and the SMP. In this study, we tested the release efficiency of the SMP for four different gear configurations. We tested the effect of adding LED lights at two different positions and altering panel size and panel position in the trawl. The analyses were focused on two species: hake (Merluccius merluccius) and blue whiting (Micromesistius poutassou). The results showed that the position of LED lights did not significantly affect the SMP's release efficiency for any species. However, increasing panel size had a significant positive effect on the release efficiency of blue whiting, and placing the SMP in the lower panel improved the release efficiency of hake. These results highlight the challenge of simultaneously improving the selective properties of gear for species with different behaviour, especially in mixed demersal fisheries. Eficiencia de escape y selectividad de cuatro configuraciones diferentes aplicadas a un panel de malla cuadrada en la pesquería multiespecífica de arrastre del País VascoResumen: La reducción de descartes en la pesquería de arrastre del País Vasco supone un problema importante. En 2006, se introdujo en la reglamentación la posibilidad de usar un Panel de Malla Cuadrada (SMP) en la zona anterior al copo para mejorar la selectividad de la red. Sin embargo, estudios recientes manifiestan que la eficiencia de escape de los peces es baja debido a la falta de contacto selectivo entre el pez y el panel. En este estudio, analizamos la eficiencia de diferentes configuraciones del SMP. Se analizó el efecto de luces LED colocadas en distintas posiciones, el efecto del tamaño del SMP y su localización. Estudiamos la merluza (Merluccius merluccius) y la bacaladilla (Micromesistius poutassou). La posición de las LED demostró no tener ningún efecto significativo sobre la eficiencia de escape del SMP para ninguna de las dos especies. Sin embargo, aumentar el área del panel tuvo un efecto significativo en la eficiencia de escape de la bacaladilla, mientras que el cambio de posición del SMP incrementó la eficiencia de escape de la merluza a través del SMP. Estos resultados muestran el reto que supone mejorar la selectividad de un arte de pesca simultáneamente para especies demersales con comportamientos diferentes.Palabras clave: panel de malla cuadrada; luces LED; pesca de arrastre; eficiencia de escape; merluza; bacaladilla. Citation/Como citar este artículo: Cuende E., Arregi L., Herrmann B., Sistiaga M., Basterretxea M. 2020. Release efficiency and selectivity of four different square mesh panel configurations in the Basque mixed bottom trawl fishery. Sci. Mar. 84(1): 39-47. https://doi.org/10.3989/scimar.0...

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confidence: 77%

Release efficiency and selectivity of four different square mesh panel configurations in the Basque mixed bottom trawl fishery

et al. 2020

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“…However, placing LEDs around the escape exit was ineffective at stimulating fish escape through the grid escape exit. Based on the results obtained, it appears that LEDs discourage fish from getting close to the area where they are placed, which agrees with the results of Parsons et al (2012) and seems to apply especially to species such as Haddock, whose escape behavior is known to be directed upwards (Winger et al 2010;Sistiaga et al 2016). Therefore, placing the LEDs at the lower part of the Nordmøre grid could be a better option, as it can direct the fish toward the escape exit without contacting the grid first.…”

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confidence: 73%

“…In addition, turning the grid section upside down, with the escape exit facing downwards and LEDs placed at the top of the grid, could increase escape without contacting the grid for species known to seek an escape route downwards, such as Atlantic Cod and various species of flatfish (Rose and Hammond 2014;Sistiaga et al 2016). The use of a long guiding funnel similar to the one used in the Norwegian shrimp trawl fishery tended to allow a lower fraction of small bycatch fish species to escape through the escape exit than was the case with a short guiding funnel.…”

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Performance of the Nordmøre Grid in Shrimp Trawling and Potential Effects of Guiding Funnel Length and Light Stimulation

et al. 2017

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The introduction of the Nordmøre grid to shrimp trawls has reduced the issue of bycatch to that of smallsized species and juveniles that are able to pass through the grid and enter the small-meshed cod end together with the targeted shrimp. This study estimated the size-and species-selective performance of the Nordmøre grid in the configuration most often applied by fishermen and made a preliminary exploration of the effects of reducing the length of the guiding funnel in front of the grid and mounting light-emitting diodes (LEDs) around the escape exit. Experimental fishing trials were conducted in the Barents Sea to assess the size-selective properties of a 19-mm bar spacing Nordmøre grid, mandatory in this Norwegian trawl fishery targeting deepwater shrimp Pandalus borealis (also known as northern shrimp), and its potential improvement. Results were obtained for the target species and four bycatch species: redfish Sebastes spp., Haddock Melanogrammus aeglefinus, Atlantic Cod Gadus morhua, and American Plaice Hippoglossoides platessoides. In general, very few deepwater shrimp were found to escape through the escape exit, although the quantity increased slightly at larger sizes. Between 80% and 100% of the bycatch species up to a species-specific size passed through the grid and entered the cod end. A short guiding funnel decreased this for Haddock significantly by increasing the fraction of small Haddock seeking the escape exit. Further, adding LEDs around the escape exit significantly negated this effect. For the other bycatch species, the results indicated similar trends but were not statistically significant. However, considering that

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“…The causing mechanism is that fish often seem to stop just in front of the 45 grid and keep a somewhat stationary position up to several minutes before being size sorted in the 46 section and pass it in the direction of the codend. This phenomena leads to fish accumulation at the 47 entrance of the grid section, which combined with high entrance rates can result in that the grid section 48 gets blocked (or clogged) by fish, loses its sorting ability and finally breaks in some cases (Grimaldo 49 et al, 2015;Sistiaga et al, 2016). Therefore, a key to eliminate or at least significantly reduce this risk 50 for grid clogging is to ensure that the fish does not stop and accumulate in front of the grid section 51 before being size sorted by it.…”

Section: Fig 1 39mentioning

confidence: 99%

Size selection of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Northeast Atlantic bottom trawl fishery with a newly developed double steel grid system

et al. 2018

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11In recent years, Norwegian fishermen have reported problems with fish accumulation in front 12 of the mandatory sorting grids (Sort-X, Sort-V, and Flexigrid). These problems are associated with 13 high fish entry rates and low water flow through the grid sections. In this study, we replaced the lifting 14 panel in the original design of a sorting grid section (Sort-V) by another steel grid ("lower grid") in 15 order to improve water flow and increase sorting area. Two different inclination angles of this new 16 additional "lower grid" were tested. The results demonstrated that both the lower grid and the main 17 grid contributed to the release of cod and haddock. However, the release efficiency of the lower grid 18 was low compared to that of the main grid. A larger proportion of fish contacted at least one of the 19 grids with the lower grid set at 40 o compared to at 35 o . The new double grid was found to release 20 significantly more haddock between 38 and 50 cm long than the mandatory Flexigrid. For cod, the 21 sorting system was at least as good as the Flexigrid at releasing undersized fish. Thus, the new double 22 grid system represents a potential alternative to the Flexigrid. Although the Sort-V single grid releases 23 significantly more undersized cod and haddock than the new double grid system, it also releases a 24 significantly higher proportion of the targeted commercial sizes. 25

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Size selective performance of two flexible sorting grid designs in the Northeast Arctic cod ( Gadus morhua ) and haddock ( Melanogrammus aeglefinus ) fishery

Cited by 39 publications

References 18 publications

Release efficiency and selectivity of four different square mesh panel configurations in the Basque mixed bottom trawl fishery

Release efficiency and selectivity of four different square mesh panel configurations in the Basque mixed bottom trawl fishery

Performance of the Nordmøre Grid in Shrimp Trawling and Potential Effects of Guiding Funnel Length and Light Stimulation

Size selection of cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) in the Northeast Atlantic bottom trawl fishery with a newly developed double steel grid system

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