Using guarding net to reduce regularly discarded invertebrates in trammel net fisheries operating on seagrass meadows (Posidonia oceanica) in Izmir Bay (Eastern Aegean Sea)

Aydin, İlker; Gökçe, Gökhan; Metin, Cengiz

doi:10.12681/mms.425

Cited by 14 publications

(17 citation statements)

References 30 publications

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“…The significant reductions in discards observed in the present study when using a guarding net on the lead line are in general agreement with previous studies on reduction techniques for gill and trammel net fisheries in the Mediterranean (Gökçe, ; Metin et al., ; Aydin et al., ). Also the insignificant reduction of the catch of target species (green tiger prawn for this study) was similar to results reported by Metin et al.…”

Section: Discussionsupporting

confidence: 93%

Discard reduction of trammel nets in the Northeastern Mediterranean prawn fishery

et al. 2016

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In this study the effects on the discard reduction of guarding net rigged prawn trammel nets were examined with the focus on catch composition and income of fishermen for the Mersin Bay small-scale prawn fishery. A total of 15 fishing trips were carried out between September and December 2011, using the commercial net and the alternative experimental net for comparison. The results revealed that catches of the main target species, green tiger prawn (Penaeus semisulcatus), in the alternative nets were only 1.5% smaller than those of the commercial nets, and with a statistically insignificant difference (P > 0.05). However, the catch of the main discarded species, the invasive swimming crab (Charybdes longicollis), mantis shrimp (Rissoides desmaresti), and the blue crab (Portunus pelagicus) were captured 85%, 66%, 75% less often in the alternative nets, with statistically significant differences (P < 0.05). Also reduced was the labour needed to remove the catch from the alternative gear as well as a reduction in the number of tears in the net. An 8% loss of revenue from landings was estimated when using the alternative gear, however, this difference was statistically not significant (P < 0.05).

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Section: Discussionsupporting

confidence: 93%

Discard reduction of trammel nets in the Northeastern Mediterranean prawn fishery

et al. 2016

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“…Compared with previous studies such as those performed in Izmir Bay and Antalya in Turkey (Metin et al 2009, Olguner and Deval 2013, Aydin et al 2013, the modified trammel net used in the present study did not provide similar successful outcomes; although there was a reduction in by-catch, there was also a loss of earnings of target species and commercial by-catch. Vecchioni et al (2016) also reported decreased discard rates for modified trammel nets and decreased yield of commercial species in experimental trials with modified and standard trammel nets in the Egadi marine protected area in Italy, while Sartor et al (2007) found that trammel nets with a guarding net from the Livorno coast (Italy) had lower catches of more benthic commercial species than standard trammel nets.…”

Section: Guarding Net: a Successful Modification?contrasting

confidence: 92%

“…In another study performed in Izmir Bay on Mullus spp. fishery (Aydin et al 2013), discard rates decreased to about 55% to 63%, and the guarding net reduced the catches of the three main by-catch taxa (Hexaplex trunculus, Bolinus brandaris, Maja spp. ).…”

Section: Introductionmentioning

confidence: 99%

Reducción de la captura secundaria y los descartes en la pesquería costera de pequeña escala del Algarve utilizando una red de trasmallo de monofilamento equipada con una red de protección

et al. 2018

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Experimental fishing was conducted off the port of Quarteira (southern Portugal) from October 2016 to February 2017 using standard trammel nets and modified nets rigged with a guarding net. The commercial catches of trammel nets rigged with a guarding net were 46.1% and 38.0% less than those of the standard net in numbers and economic value. However, there were significantly fewer commercial discards in biomass in the modified trammel nets (68.2%) and by-catch abundance and biomass were also lower in the modified nets (41.8% and 17.3% less, respectively). For the two main fish by-catch species, the modified net caught 62.2% fewer longfin gurnards (C. obscurus) and 33.1% fewer greater weever (T. draco) than the standard nets. Timing the removal from the nets of the main by-catch and discards species revealed savings in time associated with the use of modified nets. However, net damage occurred twice as much as in the modified net, probably contributing to the reduced commercial catches. The results indicate that trammel nets with the guarding net reduce by-catch and discards and save time, but are unlikely to be adopted by fishers targeting soles due to the higher costs of the modified nets and losses in commercial catches and earnings.

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“…In this sense, damage reduction has been reported when greca was used in red mullet ( Mullus spp.) and shrimp ( Melicertus kerathurus ) fisheries at the Aegean Sea ( Metin et al, 2009 ; Aydin, Gökçe & Metin, 2013 ). In these cases, the reduction of net damage was attributed to a reduced bottom contact of the net with the seabed and the avoidance of capturing benthic invertebrates that appear to be selectively excluded by the greca .…”

Section: Discussionmentioning

confidence: 99%

Comparing the catch composition, profitability and discard survival from different trammel net designs targeting common spiny lobster (Palinurus elephas) in a Mediterranean fishery

Catanese

Hinz

Gil

et al. 2018

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In the Balearic Islands, different trammel net designs have been adopted to promote fisheries sustainability and reduce discards. Here, we compare the catch performance of three trammel net designs targeting the spiny lobster Palinurus elephas in terms of biomass, species composition and revenue from commercial catches and discards. Designs differ in the netting fiber type (standard polyfilament, PMF, or a new polyethylene multi-monofilament, MMF) and the use of a guarding net or greca, a mesh piece intended to reduce discards. Catches were surveyed by an on-board observer from 1,550 netting walls corresponding to 70 nets. The number of marketable species captured indicated that the lobster trammel net fishery has multiple targets, which contribute significantly to the total revenue. The discarded species ranged from habitat-forming species to elasmobranches, but the magnitude of gear-habitat interactions on the long term dynamics of benthos remains unclear. No relevant differences in revenue and weight of discards were detected after Bayesian analyses. However, the species composition of discards was different when using greca. Interestingly, high immediate survival was found for discarded undersized lobsters, while a seven day survival assessment, using captive observation, gave an asymptotic estimate of survival probability as 0.64 (95% CI [0.54–0.76]). Therefore, it is recommended that it would be beneficial for this stock if an exemption from the EU landing obligation regulation was sought for undersized lobsters in the Balearic trammel net fishery.

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Using guarding net to reduce regularly discarded invertebrates in trammel net fisheries operating on seagrass meadows (Posidonia oceanica) in Izmir Bay (Eastern Aegean Sea)

Cited by 14 publications

References 30 publications

Discard reduction of trammel nets in the Northeastern Mediterranean prawn fishery

Discard reduction of trammel nets in the Northeastern Mediterranean prawn fishery

Reducción de la captura secundaria y los descartes en la pesquería costera de pequeña escala del Algarve utilizando una red de trasmallo de monofilamento equipada con una red de protección

Comparing the catch composition, profitability and discard survival from different trammel net designs targeting common spiny lobster (Palinurus elephas) in a Mediterranean fishery

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