Effect of ground gear modification on bycatch of rays in mediterranean bottom trawl fishery

Fakıoğlu, Y.E.; Özbilgin, Hüseyin; Gökçe, G.; Herrmann, Bent

doi:10.1016/j.ocecoaman.2022.106134

Cited by 10 publications

(10 citation statements)

References 40 publications

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“…The mitigating method in the ARCH is quite different, as it creates an escape zone for mobile benthic species between the netting panel and the seafloor; the escape apertures were sufficiently large to allow smaller batoids to pass beneath the trammel net without becoming entangled. A similar modification is reported for ground gear trawl by Fakıo glu et al [30]. In fact, Torpedo in the commercial survey had smaller bodies than the other two rays (figure 6), with a significant portion of the captured population below 300 mm total length, and 200 mm disc-width which is the utmost aperture width in the ARCH.…”

Section: Discussionsupporting

confidence: 79%

“…A similar modification is reported for ground gear trawl by Fakıoğlu et al . [30]. In fact, Torpedo in the commercial survey had smaller bodies than the other two rays (figure 6), with a significant portion of the captured population below 300 mm total length, and 200 mm disc-width which is the utmost aperture width in the ARCH.…”

Section: Discussionmentioning

confidence: 99%

“…The majority of these species inhabit coastal habitats [28,29] and have been observed to remain close to the seafloor. That falls within the operational range of SSF thus being impacted primarily by the bottom half of the nets [30]. Gear modification of this type is more related to the technical properties of the netting panel, so that animals would bounce off the net rather than becoming entangled.…”

Section: Introductionmentioning

confidence: 99%

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Mitigating bycatch in Mediterranean trammel net fisheries using species-specific gear modifications

Ganias,

Karatza,

Charitonidou

et al. 2023

R. Soc. open sci.

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Small-scale fisheries (SSF) use static gear which are thought to interact with marine ecosystems more benignly than towed gear. Despite this, trammel nets, one of the most extensively used type of fishing gear in the Mediterranean SSF, generate large amounts of discards, which can account for 25% or more of the captured biomass. Discarded organisms may include endangered or threatened species such as elasmobranchs, as well as non-commercial invertebrates that damage fishing gear or cause disentanglement delays. We evaluated various trammel-net gear modifications, including (i) the use of a guarding net attached to the footrope, (ii) increasing the length of the rigging twine between the footrope and the netting panel, and (iii) decreasing the mesh size of the outer panels. The last two modifications were successful in lowering captures of the marbled electric ray Torpedo marmorata , which is commonly discarded in the study area. Both sorts of modifications are relatively simple, their manufacturing does not represent an added cost to implement, and most importantly they do not negatively affect the catch of the target species. The current study shows that prior evaluation of the discard profile of distinct métiers is essential to accomplish species-specific gear modifications and underlines the importance of collaboration among scientists, fishers and gear manufacturers.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mitigating bycatch in Mediterranean trammel net fisheries using species-specific gear modifications

Ganias,

Karatza,

Charitonidou

et al. 2023

R. Soc. open sci.

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“…However, whether the bycatch species are swimming out of the nets after capture, or avoid initial capture in the trawl remains unknown. Although some studies have previously deployed cameras to assess the general behaviour of species within trawl scenarios (Abangan et al., 2023; Fakıoğlu et al., 2022), direct observations with cameras can be difficult to obtain due to low light availability and harsh conditions during trawling (Rose et al., 2005). For fishing with light trials, a video camera has previously been deployed in a trawl, where footage showed Chinook salmon exiting a net via an illuminated escape panel (Lomeli & Wakefield, 2012, 2019).…”

Section: Discussionmentioning

confidence: 99%

The use of vision modelling to design bycatch reduction devices using light

Somerville,

Blount,

Stevens

2024

Fish and Fisheries

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Artificial light can be used to deter unwanted non‐target catch (bycatch) from fishing gear, which is thought to be achieved by repelling bycatch, or highlighting escape routes on nets. To select for responses in bycatch species, light should (1) cause the bycatch species to avoid capture, and (2) not invoke the same reaction in target species. One way to maximise the chance of a bycatch species responding to light is to ensure the light colour used is more visible to bycatch species. Some studies have considered the visual sensitivity of certain species to address this. In particular, the wavebands of light that a species is sensitive to. However, using this measurement alone is incomplete as it does not consider other factors that affect visibility, such as the ambient light spectrum, and wavelength‐dependant light attenuation in different water types and depths. To account for these variables, and to more accurately predict how both target and bycatch species view light colours in a fishing context, we used a model of the vision of commercially relevant species in fisheries across the world. From this, we show whether a light colour is more visible to a bycatch species compared to a target species in a particular depth and water type, and how modelling can be used to make informed assessments of the selection of relevant light colours in fishing. We also discuss the limitations of using vision models alone and the need for corresponding behaviour and/or fishing trials with lights.

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“…Most of the scientific studies investigating the catch patterns, size and species selectivity of trawls usually focus on a few species. These are often the most economically important species [ 11 ] or most vulnerable species requiring urgent management measures [ 12 ]. On the contrary, the multispecies nature of Mediterranean bottom trawl fisheries is rarely addressed, despite the growing need for ecosystem-based fishery management for conserving biodiversity [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Every animal matters! Evaluating the selectivity of a Mediterranean bottom trawl fishery from a species community perspective

et al. 2023

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Bottom trawl fisheries often catch several species simultaneously. However, most studies addressing the catch performance and selectivity of a specific trawl focus on a few commercially important or most vulnerable species requiring management measures. By contrast, the present study considers the multispecies nature of Mediterranean bottom trawl fisheries through a holistic approach that accounts for the full species community in the catches. Specifically, we evaluated and compared the catch performance of the two codends allowed for this fishery, made of 40 mm square (SM40) and 50 mm diamond (DM50) meshes. Results showed that 50 and 80% of the catch in weight and count numbers, respectively, consisted of species without commercial value, demonstrating that large proportions of the catch are not considered when using the existing approach to evaluate the ecological impact of the fishing activity. Significant differences in catch profiles between the two codends were observed, especially for two commercial flatfish species, Arnoglossus laterna and Citharus linguatula, with larger contributions in the SM40. Further, the SM40 codend had a significantly higher retention, compared to DM50 codend, for specific sizes of Merluccius merluccius and Mullus barbatus. The outcomes of the study can be useful for the Mediterranean bottom trawl fisheries management.

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Effect of ground gear modification on bycatch of rays in mediterranean bottom trawl fishery

Cited by 10 publications

References 40 publications

Mitigating bycatch in Mediterranean trammel net fisheries using species-specific gear modifications

Mitigating bycatch in Mediterranean trammel net fisheries using species-specific gear modifications

The use of vision modelling to design bycatch reduction devices using light

Every animal matters! Evaluating the selectivity of a Mediterranean bottom trawl fishery from a species community perspective

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