Reducing flatfish bycatch in roundfish fisheries

Santos, Juan; Herrmann, Bent; Mieske, Bernd; Stepputtis, Daniel; Krumme, Uwe; Nilsson, Hans C.

doi:10.1016/j.fishres.2015.08.025

Cited by 55 publications

(29 citation statements)

References 28 publications

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“…The new selection system includes a guiding device to enhance fish contact with the SLEP. Mounting selective devices in the sides of the gear has been demonstrated to be efficient in releasing small roundfish (Swedish codend) (Madsen 2007) or flatfish species (FRESWIND) (Santos et al 2015). In the present study, the aim with this alternative positioning is to increase the probability that species such as hake are sizeselected by the SMP on their way to the codend.…”

Section: Introductionmentioning

confidence: 95%

“…1). The strategy of mounting a guiding device in the central path of the cross section of the gear to encourage fish contact with the escape windows is analogous to the strategy applied in the FRESWIND concept, which also includes a deflector mounted in front of the escape zone (Santos et al 2015).…”

Section: Slep Design and Experimental Gearmentioning

confidence: 99%

“…For SMPs to work efficiently in these fisheries, it is necessary that fish identify the potential escape zone (the section of the gear where the SMP is mounted), altering their swimming path towards the SMP to make contact with it. In this context, contact can be defined as the attempt made by the fish to use the selection device to escape (Sistiaga et al 2010;Santos et al 2015). Once such contact occurs, the size selection properties of the device will determine the possibilities of escapement for the fish.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Square mesh panels in demersal trawls: does lateral positioning enhance fish contact probability?

Santos

Herrmann

Otero³

et al. 2016

Aquat. Living Resour.

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Square mesh panels (SMPs) are often integrated into trawl sections ahead of diamond-mesh codends to improve release efficiency of undersized individuals of some species. Often, these release panels are integrated into the top panel of the trawl. This is particularly true for some mixed-trawl fisheries in western European Atlantic waters, where a diamond-mesh codend with a mesh size of only 70 mm can be applied, on the condition that an SMP with a mesh size of at least 100 mm is integrated into the upper panel of the trawl. The purpose of this SMP is to avoid catching undersized hake, for which the codend of 70 mm diamond mesh has been shown to have insufficient release potential. However, some studies have demonstrated this configuration to have poor release efficiency because most of the hake simply do not make contact with the SMP. Based on these poor results, we tested the release efficiency using 10 m long SMPs, integrated into the sides of the trawl in the last tapered section of the belly. The system is supplemented by a pentagon-shaped device, mounted in the belly to guide fish towards the SMPs. Based on the data collected we quantified the contact probability, i.e. the fraction of individuals that, during their travel towards the codend, came into contact with the SMPs to be size selected by them. Analysis revealed that 62% of hake (Merluccius merluccius), 44% of four-spotted megrim (Lepidorhombus boscii), 51% of Norway lobster (Nephrops norvegicus), and 41% of blackmouth catshark (Galeus melastomus) made contact with the SMPs. Therefore, the contact probability estimated for side long escape panels (SLEP) by far exceeded that of SMPs integrated into the top of the gear. Based on these promising results, SLEP might be a potential tool for improving species and size selection also in other trawl fisheries where the traditional use of SMP's is not effective.

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Section: Introductionmentioning

confidence: 95%

Section: Slep Design and Experimental Gearmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Square mesh panels in demersal trawls: does lateral positioning enhance fish contact probability?

Santos

Herrmann

Otero³

et al. 2016

Aquat. Living Resour.

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“…Bycatch reduction devices, such as grids (Fonseca et al 2005), horizontal separator panels (Ferro et al 2007) or topless trawls (Revill et al 2006) have already proven to significantly reduce discards in fisheries. However, the diversity of species caught in multispecies fisheries, their corresponding morphologies and behaviours, as well as the variability in their MCRS may impede the overall efficiency of a given selective device (Bullough et al 2007;Ryer 2008;Krag et al 2014;Santos et al 2015). Improvements of fishing gear selectivity in multispecies fisheries remain challenging and experimental testing of various selective techniques continues in Europe (e.g.…”

Section: Introductionmentioning

confidence: 99%

What can be expected of a T90 extension piece to improve selectivity in bottom trawl multispecific fisheries in the Bay of Biscay?

et al. 2018

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In the Bay of Biscay, the selective properties of otter trawls have mainly been studied with regard to single species. However, for bottom trawl multispecific fisheries targeting fish, it remains challenging to find a selective device capable of limiting catches of small individuals of several species without commercial losses. The present study focuses on an innovative technical solution to reduce catches of undersized individuals in a multispecies bottom trawl fishery in the Bay of Biscay. We tested a cylinder made of 100-mm diamond meshes turned at 90°, namely T90 inserted in the extension piece. We present the selectivity results obtained for six commercial species. This device allows the escape of small Solea solea, Trachurus trachurus and Spondyliosoma cantharus individuals. No commercial losses of Sepia officinalis were recorded. Patterns for Dicentrarchus labrax and Mullus surmuletus require further investigation due to limited fish size ranges in the dataset.

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“…The parameters SP, L50, and SR were estimated with equation 8, and the estimation in equation 9included the additional parameter C. If both equations (8) and (9) could describe the experimental data, then that with the lowest Akaike's information criterion (AIC) value (Akaike, 1974) was selected for modeling the buffer towing size selectivity. Also, both models are structural models, and are thus robust for extrapolations outside the range of the length classes that were measured (Santos et al, 2016). We estimated 95% confidence intervals (CIs) for the catch comparison curve and the resulting buffer towing size selection curve using double bootstrapping for unpaired catch comparison data (Sistiaga et al, 2016).…”

Section: Figmentioning

confidence: 99%

Escape rate for cod (Gadus morhua) from the codend during buffer towing

Brinkhof

Herrmann²,

Larsen

et al. 2017

ICES Journal of Marine Science

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The high abundances of Northeast Arctic cod (Gadus morhua) in the Barents Sea have led to the development of a new fishing tactic called buffer towing. On factory trawlers, the trawl is deployed immediately after taking the catch onboard, a tactic used to ensure a continuous supply of fish is being processed. If the desired amount of fish is caught before the catch from the previous haul has been fully processed, the trawl is lifted off the seabed and towed at a given depth at low speed. This is called buffer towing. Cod that escape from the codend when the trawl is shallower than the initial fishing depth are exposed to an increased likelihood of barotrauma-related injuries, increased disease susceptibility, and predation, which could be lethal, or affect growth and reproduction capability. Therefore, this study quantified the escape rate and size selectivity during buffer towing of cod. A new analytical method was applied that allows using the same trawl configuration as applied during commercial fishing and avoids potential bias in the assessment of buffer towing size selection. Our results demonstrated a significant size selection for cod during buffer towing where cod measuring up to at least 42 cm in length were proven to escape. In particular, at least 60% of cod measuring 20 cm were estimated to escape during buffer towing. For cod measuring 30 and 40 cm, at least 53 and 45% were estimated to escape during buffer towing, respectively.

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Reducing flatfish bycatch in roundfish fisheries

Cited by 55 publications

References 28 publications

Square mesh panels in demersal trawls: does lateral positioning enhance fish contact probability?

Square mesh panels in demersal trawls: does lateral positioning enhance fish contact probability?

What can be expected of a T90 extension piece to improve selectivity in bottom trawl multispecific fisheries in the Bay of Biscay?

Escape rate for cod (Gadus morhua) from the codend during buffer towing

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