Untitled

Dereli̇, Hakkı; Aydın, Celalettin

doi:10.4194/1303-2712-v16_4_25

Cited by 9 publications

(6 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Regarding the European hake, one of the most landed and overexploited demersal species in the whole region [48], the two codends were unable to avoid the catch of individuals either below the length of first maturity (more than 30 cm; [49, 50]) or below the MCRS of 20 cm. This is in line with several selectivity studies conducted on SM40 and DM50, where the predicted 50% retention length (L50) was always lower than 20 cm in different areas (Adriatic Sea [21,51,52]; Aegean Sea [53][54][55][56]; Alboran Sea [57]; Balearic Islands [58,59] Tyrrhenian Sea [60]). Accordingly, in the present study, a discard ratio of 9-23% of the total catch in number of hakes was estimated.…”

Section: Plos Onesupporting

confidence: 89%

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

et al. 2023

View full text Add to dashboard Cite

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.

show abstract

Section: Plos Onesupporting

confidence: 89%

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

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Given by the results MLS regulation will be implemented by the TFR for the sustainable fishery of the rose shrimp. (F, Fryer's; P, pooled); MSh, mesh shape (D, diamond-; S, square-; H,hexagonal-;T90, 90 o turned mesh); MS, mesh size; L50, mean value of retention length at 50%; SR, selection range To the best of our knowledge, there is only one study about T90 turned mesh codends for horse mackerel in the Aegean Sea (Dereli and Aydın, 2016). Among three different mesh configurations, the highest L50 value (17.1 cm) for horse mackerel was obtained from T90 codend by researchers.…”

Section: Discussionmentioning

confidence: 99%

“…Their results show that the use of larger diamond mesh codend increases the L50 values for M. merluccius. Furthermore, the analysis of selectivity presented that square mesh codend positively affected L50 of hake; this codend increased the size of escapement in the Mediterranean (Guijarro and Massuti, 2006;Ordines et al, 2006;Lucchetti, 2008;Aydın and Tosunoğulu, 2010;Özbilgin et al, 2012;Dereli and Aydın, 2016). But none of them mentioned T90 codends.…”

Section: Discussionmentioning

confidence: 99%

“…Deval et al (2016) estimated the selectivity of the same mesh size (50 mm) of T0 and T90 codends in deep water demersal trawl fisheries for P. longirostris, Plesionika martia, Aristaeomorpha foliacea and Aristeus antennatus. Dereli and Aydın (2016) gave selectivity results of four codends; two different mesh sizes of diamond mesh codends, square mesh codend and turned mesh codend for M. barbatus, Merluccius merluccius, Trachurus trachurus and Dentex moroccanus. İlkyaz et al (2017) studied the selectivity of 90 o turned meshes of three different mesh size codends for bogue (Boops boops) in the Eastern Mediterranean.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Selectivity of turned meshes codends for Deepwater Rose Shrimp (Parapenaeus longirostris), Horse Mackerel, (Trachurus trachurus) and European Hake (Merluccius merluccius) in the Aegean Sea

Genç¹,

Atamanalp

Aydın

2018

EgeJFAS

View full text Add to dashboard Cite

More than fifty published on demersal trawl codend selectivity studies have been carried out in the Mediterranean waters of Turkey since the mid-1980s. In this study, in an attempt to enhance the size selectivity of three species in the Aegean Sea trawl fisheries, three 90 o turned meshes codens were investigated. Experiments were carried out in the Kuşadası Bay of the Eastern Mediterranean, between 19 January and 29 March 2015 with commercial stern trawler. The meshes of tested codends were turned 90 o , two of them have 44 mm mesh size with 300 and 150 meshes around codend circumferences (44T300 and 44T150). The other has 40 mm mesh size with 165 meshes around codend circumferences (40T165). Individual hauls and mean selectivity parameters were estimated by using the CC2000 and EC-Modeller softwares, respectively. The mean L50 values of 44T300, 44T150 and 40T165 were 17.5 ± 0.2 mm, 18.6 ± 0.1 mm and 17.1 ± 0.2 mm carapace length for shrimp, 16.4 ± 0.4 cm, 17.1 ± 0.4 cm and 14.8 ± 0.2 cm total length for horse mackerel, respectively. The pooled L50 values of, 12.8 ± 0.5 cm, 13.2 ± 0.6 cm and 12.1 ± 0.1 cm total length for hake. While there are no differences between L50 values of 40T165 and 44T300 for deepwater rose shrimp (p>0.05), there are significant differences for horse mackerel (p<0.05). The likelihood ratio test results showed that there were no significant differences among all codends for European hake. In conclusion, any effort such as using square mesh, turned mesh codends or halved the number of meshes in the codend to release immatures of some species, is probably to cause the loss of marketable sizes of other species in the Mediterranean. This economical loss of revenues is the essential concern of fishermen that prevents them using alternative codend designs, though such designs are technically applicable. Consequently, the losses of income caused by using T90 mesh codend and halving the number of meshes around codend circumference should also be investigated in future studies.

show abstract

“…Because adopting a larger mesh size in the codend implies a strong reduction in the valuable fraction of catch, different technical solutions are being tested to modify the mesh shape to reduce the unwanted by-catch from trawling in the Mediterranean Sea. Considering the selectivity of the T90 (i.e., a diamond mesh turned 90°) codend, this solution was tested in the Adriatic Sea (Petetta et al, 2020) and the Aegean Sea (Dereli and Aydin, 2016;Deval et al, 2016;Gençet al, 2018), but not in the Strait of Sicily. The T90 codend, compared to other meshes currently used by trawlers, should remain more open during fishing operations, allowing undersized fishes and shrimps to escape.…”

Section: Introductionmentioning

confidence: 99%

Exploring the feasibility of technological transfers of two by-catch reduction devices in the crustacean bottom trawling of the central Mediterranean

et al. 2023

View full text Add to dashboard Cite

IntroductionMost Mediterranean fish stocks are overexploited owing to high fishing efforts and poor exploitation patterns. Demersal trawl fisheries are considered the most impactful fishery type because of the high quantities of unwanted catch that is then routinely discarded at sea.MethodsIn the present study, two types of by-catch reduction devices (BRDs), that is a sorting grid (Grid-T45 40 mm) and a T90 50 mm codend, were compared to a typical commercial bottom trawl net (control) in terms of size structures and catch per unit effort to assess the effect of gear modification on the selectivity of crustacean fisheries in the central Mediterranean Sea. In particular, three randomly selected trawlers were involved in a paired hauls experiment fishing at the same time in the same fishing ground. Each trawler carried out four hauls per day during a 3-day campaign for a total of 36 hauls. The target species of the fishery is Parapenaeus longirostris (herein DPS), and the main commercial by-catch is Merluccius merluccius (herein HKE).ResultsThe results showed that the landing per unit effort (LPUE) of DPS was higher for Grid-T45 40 mm net, although it did not differ significantly from that of the control net. Conversely, the discard per unit effort (DPUE) of the control net was significantly higher than of both BRD configurations. For HKE, a slightly higher LPUE was recorded using the T90 50 mm codend compared to that of the control, but this result was not statistically significant. The lowest DPUE was found for the T90 50 mm codend, with significant differences compared to that of the control and Grid-T45 40 mm net. The catch comparison of the size structures analysed through generalised linear mixed models highlighted that the Grid-T45 40 mm net was more effective in catching adult DPS, whereas the T90 50 mm codend was more selective for adult HKE.DiscussionIn conclusion, although further studies should be carried out in future to test the performance of the BRDs in different areas and seasons, the investigated gear seems to be promising for reducing the catch of undersized individuals and contributing to mitigating the current overfishing of DPS and HKE.

show abstract

Untitled

Cited by 9 publications

References 28 publications

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

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

Selectivity of turned meshes codends for Deepwater Rose Shrimp (Parapenaeus longirostris), Horse Mackerel, (Trachurus trachurus) and European Hake (Merluccius merluccius) in the Aegean Sea

Exploring the feasibility of technological transfers of two by-catch reduction devices in the crustacean bottom trawling of the central Mediterranean

Contact Info

Product

Resources

About