Questioning the effectiveness of technical measures implemented by the Basque bottom otter trawl fleet: Implications under the EU landing obligation

Alzorriz, Nekane; Arregi, Luis; Herrmann, Bent; Sistiaga, Manu Berrondo; Casey, John; Poos, Jan Jaap

doi:10.1016/j.fishres.2015.11.023

Cited by 38 publications

(38 citation statements)

References 41 publications

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“…However, increasing the selectivity of the gear is not straightforward. For example, in the same fishing area, the inclusion of a top square mesh panel has not produced significant changes in the size composition of the catches (Alzorriz et al 2016). Furthermore, the results from the simulation show no capital-based incentives to increase the MMS.…”

Section: Consultation With Skippersmentioning

confidence: 90%

Bioeconomic assessment of a change in fishing gear selectivity: the case of a single-species fleet affected by the landing obligation

et al. 2017

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Summary:The European Union Common Fisheries Policy has established a discard ban, which states that fish below a reference size cannot be sold directly for human consumption. In a fishing effort-regulated fishery, the discard ban can result in extra handling, storing and landing costs. In an output-regulated fishery, this policy might also limit the effort levels as all the catches count against the quota. In both cases, this regulation can reduce the economic performance of the companies, even in single-species fisheries. A possible solution is to increase the mesh size, thus retaining fewer small individuals. To study this option, a bioeconomic simulation of a change in the gear selectivity from 100-to 120-mm minimum mesh size (MMS) was performed. The results show that the private perspective (profits) does not change. Furthermore, due to the lower retention of 120 mm MMS, the efficiency of a fishing day was reduced by 5% and 2.5%, from the point of view of capital and labour productivity, respectively. In contrast, gross revenues increased by 1.5% and crew compensation by 2%. Given a societal benefit of this change in the mesh size, this gain could be re-distributed to provide an incentive for selectivity improvements.Keywords: minimum mesh size; landing obligation; minimum conservation reference size; simulation model; selectivity; hake.Evaluación bioeconómica del cambio en la selectividad de un arte de pesca: el caso de una flota mono-específica afectada por la obligación de desembarque Resumen: La Política Pesquera Común de la Unión Europa ha introducido la prohibición de descartar, estableciendo que todo pescado por debajo de una talla de referencia no puede ser vendido para consumo humano directo. En una pesquería regulada a través de limitaciones del esfuerzo de pesca, la prohibición de descartar puede generar sobrecostes de manipulación, almacenamiento y desembarque adicionales. En una pesquería regulada a través de límites en las capturas, esta política podría incluso limitar los niveles de esfuerzo ya que todas las capturas deben ser deducidas de la cuota. En ambos casos, esta regulación puede reducir el resultado económico de las empresas, incluso en el caso de una pesquería mono-específica. Una posible solución sería aumentar el tamaño mínimo de la malla, y así reducir la retención de los individuos más pequeños. Con el fin de estudiar esta opción, se ha realizado una simulación bioeconómica de un cambio en el tamaño mínimo de la malla de 100 a 120-mm. Los resultados muestran cómo la perspectiva económica privada (beneficios) no varía. Más aun, debido a la menor retención de la malla de 120 mm, la eficiencia de un día de pesca se ve reducida en un 5% y en un 2.5%, desde el punto de vista de la productividad del capital y del trabajo, respectivamente. Por el contrario, los beneficios brutos aumentan un 1.5% y la remuneración al trabajo en un 2%. Debido a la existencia de un beneficio social, la ganancia podría ser redistribuida para así ofrecer un incentivo a esta mejora de la selectividad.Palabras ...

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Section: Consultation With Skippersmentioning

confidence: 90%

Bioeconomic assessment of a change in fishing gear selectivity: the case of a single-species fleet affected by the landing obligation

et al. 2017

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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%

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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“…According to the regulations specified by the European Commission (EC 2006), the vessels participating in this fishery usually use a trawl net with a 70 mm diamond mesh codend combined with a 100 mm square mesh panel (SMP) (2 m long, 1 m wide) inserted in the upper panel of the extension piece of the trawl. However, recent studies have shown that most undersized individuals that escape the gear do so through the codend rather than through the panel (Nikolic et al 2015, Alzorriz et al 2016.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, SMPs can be an alternative measure to increase the escape of some species without excessively affecting profitability (Brčić et al 2016). Several studies have investigated the functioning and release efficiency potential of SMPs, but the release efficiency of SMPs has often been estimated to be low due to the low probability of contact of the fish with the panel (Herrmann et al 2014, Alzorriz et al 2016, Brčić et al 2018. There have been attempts to improve the fishpanel contact probability by inserting stimulating devices in the gear.…”

Section: Introductionmentioning

confidence: 99%

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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Questioning the effectiveness of technical measures implemented by the Basque bottom otter trawl fleet: Implications under the EU landing obligation

Cited by 38 publications

References 41 publications

Bioeconomic assessment of a change in fishing gear selectivity: the case of a single-species fleet affected by the landing obligation

Bioeconomic assessment of a change in fishing gear selectivity: the case of a single-species fleet affected by the landing obligation

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

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

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