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Payang is one of fishing gears that is used to catch some kinds of pelagic fish that live in the top layer of the water and tends to run into the bottom layer of the water when it has been covered by the net. The addition of top window on Payang cod end is used for selectivity in order that the fishes with the certain size outside the fishing target can get out through the window when the gear is being operated. The aim of this research was to identify and analyze the composition of fish caught from modified Payang, to find out the number of fish escaped from the square mesh cod end and to analyze the economic aspects (Revenue, Cost, Profit, and R/C Ratio) of common Payang fishing gear without window and modified Payang fishing gear with window. This research used experimental fishing method. The analysis method used were t-test analysis method, percentage breakouts of fish analysis and economic analysis method. The result showed that the fish caught by common Payang fishing gear (18 kg) was bigger than the fish caught by modified Payang fishing gear (15 kg). The catches was dominated by Trevally Fish. The result of Paired Sample t-test showed that Payang with window modification has no effect towards catch result, because it is more than α (0.396 > 0.05). The level of Trevally fish breakouts square mesh cod end was 48%. The revenue from modified Payang fishing gear was less than the revenue from common Payang fishing gear. The R/C ratio value from both of the fishing business was more than one so they were efficient to be operated continuously.

We used fish body depth to predict trap center-to-center mesh sizes that would optimize size selection of black sea bass Centropristis striata for both current and proposed minimum size limits for this species. We fished trap types of five different square mesh sizes/configurations: (1) 38.1 mm mesh, (2) 38.1 mm mesh on five sides and 50.8 mm mesh on one side (back panel trap), (3) 50.8 mm mesh, (4) 57.2 mm mesh, and (5) 63.5 mm mesh. The 38.1 mm mesh trap was the control trap type. Back panel traps are the minimally legal mesh configuration in this region while 50.8 mm mesh traps are commonly used in this fishery to further reduce culling of sub-legal black sea bass by fishers. Two previously untested mesh sizes, 57.2 and 63.5 mm, were evaluated because a previously published morphometric relationship between black sea bass body depth and total length (TL) predicted that the diagonal openings of these two respective mesh sizes would retain black sea bass close to the current (279 mm) and proposed minimum TL limits (305 mm). We estimated size selection of each experimental trap type by comparing catches of control and experimental traps. All but the back panel trap displayed relatively steep selection around the fish length at which 50% of individuals were selected ( l 50 ). Initial size at retention ( l 10 ) by the 57.2 and 63.5 mm trap types were nearly identical to current and proposed minimum fish sizes, respectively. Predictions from the body depth: TL relationship were very similar to estimates of l 10 and l 50 , based on uncompressed body depth and compression to 93%. The 57.2 mm mesh and 63.5 mm mesh trap types maintained catches of legal fish but reduced catches of sub-legal fish compared to the back panel and 50.8 mm mesh trap types. Relative to back panel and 50.8 mm mesh traps, use of 57.2 mm mesh traps would reduce rates of discard and discard mortality given current size limits in this fishery.

The blue crab Callinectes sapidus is a commercially important crustacean species fished along the Atlantic and Gulf of Mexico coastlines. Cull rings on traps are required to allow for egress of sublegal blue crabs in commercial and recreational fisheries in this region. We undertook a study to estimate contact selectivity (retention probability) of traps with different cull-ring sizes fished for male crabs. We estimated retention probability using logistic models and catch data from 38.1-mm square mesh traps, each affixed with one size of cull rings (58.7, 60.3, or 61.9 mm internal diameter), and fished along with control traps (no cull rings). Each experimental trap type displayed relatively steep retention around its l50, the carapace width at which 50% of individuals are selected. The l50 for traps with 58.7-mm cull rings was less than the minimum legal crab size in North Carolina (127 mm carapace width) while the l50 for traps with 60.3-mm or 61.9-mm cull rings was greater than the minimum leg...

Survival estimates were obtained for the Norway lobster, Nephrops norvegicus, retained and escaping from a standard 70 mm mesh size diamond and a modified 55 mm square mesh codend, on board a commercial vessel in fishing grounds off the Portuguese south coast. Ten hauls were carried out, five with each experimental codend, plus three creel sets for the capture of a control group in an adjacent non-trawled area. A total of 571 lobsters were sampled upon arrival on vessel deck, either captured in the codend or retained in the codend cover. In addition, a total of 25 individuals were caught with creels. They were assessed for physical damage and vitality and subsequently placed in cages which were deployed in the same adjacent area for 48 h. Average survival rates were 0.18 and 0.17 for retained individuals and 0.17 and 0.30, for individuals escaping through diamond and square meshes, respectively, and 0.84 for creeled individuals. A discussion is carried out stressing the difficulty in disentangling the influence of the different factors contributing to condition and mortality of individual lobsters.

The overall objective of this study was to evaluate the behavior of different codend designs to provide basic information that is relevant for implementing technical management measures, improving selectivity and catch quality, and reducing energy consumption. Six different codend designs were evaluated: a traditional diamond mesh codend; a T90 codend (meshes turned 90°); a Bacoma codend with diamond meshes in the lower panel and square meshes in the upper panel; a Bacoma codend with the square meshes orientated in the T0 direction; a two panel square mesh codend; and a four panel square mesh codend. The codends were tested in a flume tank with flow of 1.8 knots/h. A simulated catch of 500 kg was placed in the tested codend. A motion tracking system was used with four track markers placed on each of three successive cross-sections and a single marker at the end of the codend. This made it possible to assess and compare the movements of the codend and the netting in three dimensions. The drag of the codends also was measured and compared.

Unaccounted fishing mortality is recognized as an important determinant in the management of bycatch, and discard survival studies have been conducted in commercial and recreational fisheries around the world. A range of environmental, operational and biological factors affect survival of discarded fish and should be considered when presenting survival estimates. The present study compared discard survival of plaice in the bottom otter trawl mixed fisheries in Skagerrak between (a) seasons, (b) target species and (c) codend designs. In the latter, a horizontally divided codend designed to reduce interactions between spiny Norway lobsters ( Nephrops norvegicus ) and fish during the fishing process was investigated for its capacity to reduce catch damages and improve fish survival. (a) In winter, survival was significantly higher (75%, Confidence Interval (CI): 61–78%) than in summer (44%, CI: 34–61%). (b) When targeting plaice, survival was significantly higher (73%, CI: 63–83%) than when targeting Nephrops (40%, CI: 14–59%) in winter. (c) Using the divided codend, an improvement in discard survival of undersized plaice was possible when targeting Nephrops , but without a significant difference from the 90 mm diamond mesh standard codend (37%, CI: 14–54%) when fish were caught in the 60 mm square mesh lower compartment (61%, CI: 48–73%). In the 120 mm square mesh upper compartment, survival was significantly higher (94% with CI: 81–100%), but few undersized individuals were caught. When targeting plaice, survival rates did not differ between codends.

The growing seal populations of the Baltic have led to more frequent interactions with coastal fisheries. The motivation for seals to interact with fishing gear is high. It provides high densities of fish. A successful means of mitigating the conflict is the pontoon trap. Seal visits here have been frequent. Seals have access to most parts of the trap system including the middle chamber, which is an overhead environment. Concerns have been raised about seals possible entanglement in this specific part of the trap. As a means of keeping seals from entering the middle chamber, two different Seal Exclusion Devices (SEDs) were tested. A diamond mesh SED and a square mesh SED, which was rotated 45°. The aim was to compare the functionality of the different SEDs with respect to seal deterrent abilities and catch composition. The hypothesis tested were (i) that seals would not be able to enter the middle chamber, (ii) that the catch would increase and (iii) that the SED would deter larger fish from swimming into the middle chamber. Catch data and underwater film were collected. Larger salmons were caught in traps equipped with SEDs. The SEDs did not affect the number of caught fish or the total catch per soak day.

Accepted manuscript version, licensed CC BY-NC-ND 4.0. Published version available at https://doi.org/10.1016/j.fishres.2018.03.020. In the laboratory, we investigated which sizes of Nephrops (Nephrops norvegicus) could pass through the meshes of different size and shape to establish a predictive model for the creels size selectivity. Predictions agreed well with the results from experimental fishing, demonstrating the reliability of this simple method. Nephrops minimum target size is 20 mm carapace length in the Mediterranean creel fishery, with some areas having restrictions on the mesh size, minimum being 36 or 40 mm. The model predicts that Nephrops below 28 and 32 mm carapace length would escape from creels with respectively 36 and 40 mm mesh size, implying a suboptimal exploitation pattern. Our method provides easy and quick identification of optimal mesh size and shape without the exhaustive sea trials with various creel designs. It was predicted that a square mesh of 30 mm would better match the desired exploitation pattern. The method could easily be adopted to other species and different creel fisheries, helping to determine optimal mesh matching a prescribed exploitation pattern.

The square mesh topology is often used for interconnecting nodes in parallel computers. However, the large diameter of the basic mesh topology makes it suitable for solving problems where communication takes place mostly among neighboring nodes. The new 2-D mesh topology with optical interlinks reduces the diameter of the mesh topology, by interlinking nodes that are separated by half the number of nodes in each dimension. In this paper, parallel algorithms have been developed to demonstrate the effectiveness of this new variant over the basic topology. The presence of additional optical interlinks helps in designing faster solutions to various problems without increasing design complexity. The problems that have been addressed are data communication, matrix multiplication, and solving linear systems.

Akdeniz ekosistemi için önemli sorunlardan bir tanesi düşük torba seçiciliği ve yüksek ıskarta oranları ile karakterize olan dip trol balıkçılığıdır. Birçoğu trol torbasının göz açıklığı ve şekli ile ilgili olmak üzere, dip trol balıkçılığında torba seçiciliği üzerine çok sayıda araştırma mevcuttur. Bu çalışmalar çerçevesinde, Akdeniz Genel Balıkçılık Komisyonu (GFCM), Akdeniz'de 40 mm kare (S40) ya da 50 mm baklava (D50) şeklinde daha seçici trol torbalarının kullanımını tavsiye etmektedir. Ancak, artan seçiciliğin ekosistemin ekolojisi üzerine etkileri tam olarak bilinmemektedir. Bu çalışmanın amacı, artan trol torba seçiciliğinin ekosistem ve ana hedef türler üzerine potansiyel etkilerinin araştırılmasıdır. Bu çalışma, ticari trol torbası (44 mm baklava şeklinde el yapımı ve gevşek düğümlü trol torbası, CD44), 44 mm baklava şeklinde trol torbası ve alternatif torbalar (D50 ve S40) için türe özgü av ve seçicilik verisi temel alınarak kurgulanmıştır. Farklı trol torbalarının ekosistem üzerine etkilerini temsil eden 4 adet Ecopath modeli geliştirilmiştir. Bu modeller 48 adet fonksiyonel gruptan oluşmaktadır ve benzer topolojilere sahiptirler. Ekosistem temelli değerlendirmenin sonucunda, dip trol balıkçılığında daha seçici torbaların kullanımının ekosistemin ve çeşitli ana hedef türlerin yararına olduğu belirlenmiştir. Başta bölgenin hedef balık türü olan barbun (Mullus barbatus) olmak üzere çeşitli ekonomik türler ve ekosistem açısından en iyi alternatif trol torbası olarak S40 tanımlanmıştır. The Poor selectivity and high discard ratios of demersal trawls are of significant concern in the Mediterranean. A large number of studies exist on codend selectivity, most of which focus on mesh size and shape. In consideration of these studies, the General Fisheries Commission for the Mediterranean recommends the use of 40 mm square-mesh (S40) or 50 mm diamond-mesh (D50) codends.However, the effects of improving codend selectivity on the ecology of the ecosystem are not well known. The goal of this study is to evaluate the potential effects of improved codend selectivity on the ecosystem and main target species, Mullus barbatus, Saurida undosquamis, Pagellus erythrinus as case species.This study is based on well-described species-specific catch and selectivity data for commercial codend (44 mm diamond mesh handmade slack knotted net, CD44), 44 mm diamond mesh codend (D44) and alternative codends (D50 and S40) in demersal trawl fisheries from Gulf of Mersin in the eastern Mediterranean. Four Ecopath models, with 48 functional groups and similar topologies were developed to represent the effect of different codends on the ecosystem. Specifically, the impact on M. barbatus S. undosquamis, P. erythrinus were described by splitting the functional group into two components according to minimum landing size (MLS).The consequences of improved trawl selectivity were assessed in the context of ecological framework approved that selective fisheries would benefit for various commercial species and ecosystem. S40 was found as the best alternative for the impacts of trawl fisheries on the ecosystem and various commercial species, particularly red mullet which is the most important commercial species in the region.M. barbatus (MLS, adult) showed the lowest trophic levels among demersal fish groups. For CD44, D44, D50 and S40 codends, the catches were calculated as 0.013 t.km-2.y-1, 0.011 t.km-2.y-1, 0.006 t.km-2.y-1 and 0.003 t.km-2.y-1 for M. barbatus (MLS) respectively.Ecological network analysis highlighted that if trawlers switched from CD44 to D50 or S40 codends, metabolic activity of M. barbatus (

Accepted manuscript version. Published version available at https://doi.org/10.1139/cjfas-2017-0461. Copyright NRC Research Press. Size selectivity of a new sorting section combining a sorting grid and a square mesh panel was tested for haddock (Melanogrammus aeglefinus) in the Barents Sea demersal trawl fishery. Sampling data for a wide size range enabled investigating the selection process for this species in detail, both for the grid and the square mesh panel. Contrary to earlier studies modelling size selectivity for grids and square mesh panels, which assume that the escape behaviour of all sizes of fish is equal, we applied a model that accounted for that haddock of different sizes can show different escape behaviour. Our results demonstrated that this model could describe the experimental data collected better than existing models. Specifically, our results showed that the likelihood for smaller haddock to seek escape through the grid and the square mesh panel was higher than for bigger haddock that still would manage to escape through the devices if they attempted. The new modelling approach presented in this study may be applicable to other species, selection devices and fisheries.

This work dealt with an essential problem of fragmentation of rocks with expansive cement. The redistribution and magnitude of stresses and displacement generated around holes were done by using Ansys Inc. Code which is based on finite element code. Blocks of rock with one hole, two holes, and nine holes drilled in square mesh and staggered mesh have been considered. Numerical results reveal that many factors can influence the mechanism of fragmentation of a rock by using expansive cement: hole diameter, hole spacing, panel mesh, expansive pressure applied, and the elastic properties of the massif. Stresses and displacements generated globally decrease when spacing holes increase. Normal stresses allow a better stress interaction between holes in the case of square mesh disposition. Staggered mesh disposition generates higher stresses than the square mesh disposition. But the square mesh disposition can be useful for controlled fragmentation in order to obtain block of rock with square geometry. For each expansive cement and rock, there exist suitable range of diameter and spacing hole which can generate high stresses for breaking the rock.

WOS: 000452121100005, The striped red mullet (Mullus surmuletus) is a commercially important demersal species caught by mixed trawl fishing in the Mediterranean Sea. Although it is not among the target species of bottom trawl operations, the striped red mullet is an important species due to its high commercial value in trawl catch composition. The primary target is to catch adult individuals while allowing the immature and juvenile fish to escape for sustainable fisheries using selective fishing gears. Various selectivity studies regarding trawl codends aimed at improving selectivity have been carried out in the past two decades. However, the selectivity sea trials generally require a great deal of work, time, and labor on the deck and are also expensive. Therefore, instead of experimental-based selectivity studies, simulation-based studies (i.e., the FISHSELECT methodology) were recently started to predict the size selectivity of species in bottom trawl fisheries. In this study, sampled individuals of the striped red mullet were used in morphological measurements, fall-through experiments, and simulation phases. Diamond mesh sizes of 40, 44, and 50 mm and a square mesh size of 40 mm of bottom trawl codends were simulated, and the L50 values were calculated as 9.87, 10.75, 12.19, and 12.3 cm for the aforementioned mesh sizes, respectively. Design guides were then created for various mesh sizes and opening angles. The study results were compared with those of previous studies on the red mullet (M. barbatus) that were conducted using the FISHSELECT methodology, and the selectivity results of these two species were found to be similar., Scientific Research Commission of Ege University [16-SUF-008], The research documented in this paper was conducted as part of the Ege University Scientific Research Project No: 16-SUF-008 supported by the The Scientific Research Commission of Ege University and it is also part of MSc thesis of Enis Noyan Kostak. This study was awarded 'Best oral presentation' in the 19th National Fisheries Symposium of Turkey which was organized by Sinop University between 12-15 September 2017.

Many fishing methods result in significant catches of non-target species or individuals that are too small to be retained for economic values or within quota regulations. In the Baltic Sea trap fishery, the major problem is the bycatch of juvenile and non-marketable whitefish (Coregonus maraena) which constitutes a threat to the sustainability of the fishery and a time-consuming problem for the fishers. This study evaluates the effectiveness of a modified fish trap in reducing such bycatch. An encircling selection panel consisting of 50 × 50 mm square mesh netting was installed in a pontoon fish chamber of a salmon/whitefish trap. Comparative fishing was conducted against a control trap without selection panel in the inshore waters of the Bothnian Sea. Comparisons of catch compositions between the traps showed that there was a 72% reduction in juvenile whitefish catch in the experimental trap. The length at 50% retention (30.1 cm) corresponded well to the minimum market size (>30 cm) of whitefish that are desired for the local market. Fishers are advised to use a netting panel of 50 × 50 mm square mesh for their traps to reduce undersized whitefish. The results are important for the sustainability of whitefish stocks in the Baltic Sea.

Many jurisdictions have introduced management regimes prohibiting or limiting discarding, and a key objective of the European Union Common Fisheries Policy is the gradual elimination of discards. One way of reducing the catch of unwanted fish is to use more size-selective gears. Gear-based management options can best be explored using models that predict size selection across a wide range of variables related to gear design. Such a model is developed for haddock (Melanogrammus aeglefinus) through a meta-analysis of 21 trials of codend selection and 19 trials of the combined selection of the codend and a square mesh panel. Individual-haul estimates of the 50% retention length (l50) and the selection range (SR) are related to a set of explanatory variables through a structural model that describes the dual process of panel and codend selection. Codend l50 and SR are positively related to codend mesh size and negatively related to the codend twine diameter. Codend l50 is also negatively related to the number of open meshes around the codend circumference. Panel l50 increases with panel mesh size. The panel contributes more to gear selection as it is moved closer to the codline. The panel is most effective between November and January and least between May and July, periods which broadly coincide with peak and poor haddock condition. The results are illustrated for a typical trawler targeting haddock in the Scottish whitefish sector, and the utility of the model for gear design and legislation is discussed.

Summary Three bycatch reduction devices (BRDs), i.e. the Turtle Excluder Device (TED), Square Mesh Codend (SMC) and Fisheye (FE), were tested to evaluate their feasibility in the Kuwait shrimp-trawl fishery. All three BRDs could be fitted to a shrimp trawl and normal fishing activities could be conducted both on an industrial trawler and an artisanal dhow boat. The comparisons of the catch from a net equipped with a BRD on one side and a standard net (exact same net configuration but without a BRD device) on the other side of a double-rigged shrimp trawler (steel boat) showed different results in the three BRD types. The net fitted with a TED performed well without capturing any turtles or large animals, and did not significantly reduce shrimp catch or fish bycatch (124.4: 117.0 and 852.0: 905.8, both P > 0.05). Although the SMC reduced both shrimp catch and bycatch in general, the Wilcoxon's signed rank test showed a significant difference only among bycatch (1034.2: 1147.3, P

WOS: 000413432700005, This study was done on the use of 40 mm square mesh codend in otter trawl, the minimum measure in Mediterranean deep trout fishing in Eastern Mediterranean in accordance with European Union (EU) regulations. Brushtooth lizardfish Saurida undosquamis (Richardson, 1848) is an important catch component in this region. The lumen of the square mesh being always open, makes it easy for the fish to escape. However, the fish can sometimes get stuck in the mesh while trying to escape, which can lead to economical loss in commercial fishing. Effect of shortening the length of codend on the rate of entangling of brushtooth lizardfish was assessed. The 8 m long and 40 mm square mesh codend was shortened to a length of 4 m. It was observed that shortening the net had no negative impact on the selectivity of the gear and in both cases there was an equal amount of loss and dissatisfaction for the fishermen due to the damage caused while taking out the fish that got entangled in the codend meshes., BAP Foundation of Mustafa Kemal University, Authors thank BAP Foundation of Mustafa Kemal University for their financial support.

In the English Channel and Southern Bight, French demersal trawlers target a mix of demersal species including whiting (Merlangius merlangus). The discard ban to be implemented in January 2016 motivated fishermen to look for technical measures to reduce unwanted catches of undersized individuals (

Modifications of a traditional fyke net design were trialled in 42 hauls over 5 months at 42 locations in the Thames estuary, London. These trials were to determine whether the modified nets could be used to catch invasive mitten crabs while at the same time releasing endangered eels, back into the river. The modifications included rings of different diameters fixed into the netting to provide escape apertures and also a variation in mesh size. A standard, unmodified net was included as a control. Captured mitten crabs, eels and other fish by-catch were measured and recorded for all deployed nets. Mitten crabs and eels were caught in all nets except those of the largest mesh size (70 mm) which caught no eels. This may have been the combined effect of the mesh size and it being set on the square, versus the normal diagonal netting which may become increasingly constricted in one axis, under tension. Such a square mesh net could be used to trap crabs of carapace width > 65 mm, while releasing all eels. The smallest rings, 22 mm internal diameter, inserted into the mesh may have allowed the escape of eels < 35 cm length, but retained larger, market legal, individuals. This suggests that a slightly smaller escape ring could potentially be used to release eels of ≤ 30 cm in length, in line with current regulations.

The Council Regulation (EC) no. 1967/2006 introduced the adoption of the 40 mm square-mesh or alternatively a 50 mm diamond-mesh codend for trawlers of EU Member States. In this context, the main aim of the current study was to compare the catch composition of Lampedusa’s shallow-water trawl fishery, in terms of retained and discarded fraction, using the 24 mm square-mesh codend (illegal and supposed unselective) and the 50 mm current diamond-mesh codend (legal and supposed selective). During 2012, 21 hauls were performed, under commercial conditions, with the 24 mm square mesh codend and 27 with the 50 mm diamond mesh codend in an area of the Strait of Sicily at depths from 40 to 80 m. The introduction of a 50 mm diamond-mesh, although not significantly, reduced the CPUEs of retained and discarded fraction compared with the 24 mm mesh. Moreover, for most target species and their size classes (especially immature individuals), the legal mesh recorded a lower mean number of specimens than the banned mesh size. All these advantages aside, the discard of the shallow-water trawl fishery, in Lampedusa, represented a very important part of the total catch (more than three-quarters) by both mesh sizes and a large amount of this was represented by species and habitat of conservation concern. Our results suggest that spatial restrictions, such as no-take zones, could be a more effective management tool to protect this sensitive ecosystem in the area than the technical measures (e.g. reduction of mesh size) imposed today by the EU.

This is a pre-copyedited, author-produced version of an article accepted for publication in ICES Journal of Marine Science following peer review. The version of record Sistiaga, M.B., Herrmann, B., Grimaldo, E., Larsen, R.B., Olsen, L., Brinkhof, J. & Tatone, I. (2017). Combination of a sorting grid and a square mesh panel to optimize size selection in the North-East Arctic cod (Gadus morhua) and redfish (Sebastes spp.) trawl fisheries. ICES Journal of Marine Science. 75(3), 1105-1116 is available online at: https://doi.org/10.1093/icesjms/fsx231 Sorting grids and square mesh panels are the two most-applied technical devices to supplement codend size- and species-selection in demer- sal trawls. In the Barents Sea gadoid fishery, the compulsory size-selectivity system comprises a mesh section with a sorting grid followed by a diamond mesh codend. We tested the size-selective performance of a new sorting section that comprised a sorting grid combined with a square mesh panel as a potential alternative for the grid sections currently in use. The new sorting section was shorter and therefore more maneuverable than the existing sorting grid sections. The investigation was carried out on cod and the bycatch species redfish. The grid was found to contribute to the largest proportion of fish release, and the release through the square mesh panel was low. But, the results showed that the grid was successful at guiding fish not escaping through the grid to a second selection process in the panel. However, the square mesh panel did not result on the intended release efficiency except for the smallest sizes of fish, most likely because the guiding angle of the grid and the square meshes in the panel used did not provide a suitable escape path for the desired size range of fish. Therefore, optimizing the mesh size/shape in the panel and/or the guiding angle for the grid potentially could lead to the desired selectivity pattern in the new sort- ing section.

Broadband antireflection coatings for passive terahertz (THz) components are extremely important in the application of THz technology. Metallic nano-films are commonly used for this purpose. Here a new approach to realize polarization independent broadband antireflection in THz range, based on a meta-surface design is experimentally demonstrated. The internal reflection of a broadband THz pulse (spectral bandwidth of 0.06 – 4 THz) at a Si/air interface can be fully suppressed with a Cr square mesh with deep-subwavelength dimensions. Small nonuniformity of the meta-surface structure can enhance the tolerance on structural parameters for achieving the AR condition. The design concept is applicable to other metals and frequency ranges as well, which opens a new window for future AR coatings.

This paper quantifies the effects of a square mesh codend bycatch reduction device (BRD) and turtle excluder device (TED) in the deepwater eastern king prawn (Melicertus plebejus) fishery on the southeast Queensland coast, based upon on a 10-day research charter. The bycatch comprised 224 taxa, mainly gurnards, flatheads, sandpaper fish, hermit and charybdid crabs, mantis shrimps, sand dollars (i.e. sea urchins), dragonets, snipefish, carids and lizardfish. The total mean bycatch rate was comparatively low (1114.0 g ha−1 from the standard diamond mesh codend), mainly because of the relatively deep waters associated with the fishery. When the TED and square mesh codend BRD were used together the total mean bycatch rate was significantly reduced by 29% (796.0 g ha−1) compared to the standard codend, with no significant effect on the prawn catch rate or size frequency distribution. Several bycatch species experienced very large reductions in mean catch rate, due to the square mesh codend, including Graham's conger Gnathophis grahamii (98.2% reduction), dumpling squid Euprymna tasmanica (95.9%), shortsnout threadsail Aulopus curtirostris (90.6%) and sandpaper fish Aulotrachichthys sp. (90.0%). Multidimensional scaling indicated that bycatch assemblages were more affected by latitude and depth than codend type. Based on the results, we recommend that the 47.6 mm square mesh codend be made mandatory in the deepwater eastern king prawn fishery as a highly effective BRD.

Based on size selectivity data for more than 25 000 cod (Gadus morhua) collected during experimental trawl fishing with six different codends, all of which included a square mesh panel, we investigated the effect on cod-release efficiency based on the size of the square mesh panel area, position of the square mesh panel, and stimulation of the escape response. Based on the results, we were able to explain why the BACOMA codend, applied in the Baltic Sea cod directed trawl fishery, releases juvenile cod efficiently, whereas other designs, including a square mesh panel with similar mesh size, are less efficient. Our main findings reveal that the release efficiency of the square mesh panel in the BACOMA codend depends largely on the overlap of the square mesh panel and the catch-accumulation zone in the codend, where cod do not have the option of just drifting further back in the trawl when proximate to the panel. On the contrary, the reduction in panel size by 50% did not significantly affect the release efficiency when the panel overlapped with the catch-accumulation zone. It was possible to stimulate an escape response for cod to achieve a release through a square mesh panel positioned away from the catch-accumulation zone. Our findings demonstrated that this release was as efficient as for a panel mounted in the catch-accumulation zone of the codend. Devices that stimulate behaviour may improve the release efficiency of cod through square mesh panels in other fisheries where this is a problem.

Five modified trawl codends were assessed for their utility in simultaneously improving the size selectivity of cod ( Gadus morhua ) and plaice ( Pleuronectes platessa ) in the Baltic Sea. The modifications included refining the selective performance of the current Bacoma codend by increasing the mesh size of the lower panel from 109 mm double twine to 129 mm single twine and increasing the mesh size in the upper square mesh panel from 132 to 147 mm, and also making the lower panel the same design as the upper panel; i.e. a full square mesh codend. These three experimental designs were tested in conjunction with the currently legislated codends; Bacoma and T90. The most favourable selective properties with regard to simultaneously improving the selectivity for round and flatfish, considering the current minimum landing sizes (MLS) for cod (38 cm) and plaice (25 cm) in the Baltic Sea and the fish population size structures during the sea trials, were found to be the T90 codend and the Bacoma codend with a modified lower panel. For the T90 codend, the selection parameters (L50 and SR) were 43.4 and 6.7 cm for cod, and 24.7 and 2.1 cm for plaice. The selection parameters for the most effective modified Bacoma codend were 41.1 and 8.3 cm for cod and 25.2 and 3.9 cm for plaice

Karadeniz'de toplam mezgit (Merlangius merlangus euxinus) balığı avcılığının büyük bir kısmı, Türkiye kıyılarındaki geleneksel dip trol ağları ile gerçekleştirilmektedir. 40 mm ağ göz büyüklüğünde (40D) baklava gözlü ağlar bu trollerin torbalarında kullanılmaktadır. Bu çalışmada, geleneksel dip trol torbası (40D) ve farklı ağ göz büyüklüğündeki kare gözlü (36S ve 40S) trol torbaları mezgit balığının boy seçiciliği için mukayese edildi. Seçicilik verileri bir örtü torba yöntemi kullanılarak toplandı ve çekimler arası varyasyonlar hesaba katılarak analiz edildi. Seçicilik parametreleri CC2000 programı kullanılarak hesaplandı. Sonuçlar ticari olarak kullanılan 40D trol torbasının mezgit balığının olgunlaşmamış bireyleri için seçici olmadığını göstermiştir. Oysa baklava gözlü (40D) trol torbası yerine kare gözlü torba (36S ve 40D) değişikliği mezgit balığı için ağ göz seçiciliğini önemli ölçüde artırmıştır. 40S trol torbası 15,74 cm yüzde elli yakalanma oranı (L50) ile ilk üreme boyundan daha yüksektir (LM50). Sonuç olarak çalışmada denemeye alınan farklı ağ göz boyundaki tüm kare gözlü torbalar, mezgit balığının karaya çıkarılma büyüklüğü (MLS) göz önünde bulundurulduğunda uygun seçicilik sağlamıştır.

Implementing gear-based solutions to reduce bycatch in trawl fisheries can be difficult owing to fishers’ concerns over the fleet-wide applicability of results from discrete, highly controlled experiments associated with the development of such innovations. In New South Wales, Australia, a codend comprising a posterior section made from 35-mm square-shaped mesh (i.e. hung on the bar) was developed and subsequently recommended for partial implementation in a multi-species demersal trawl fishery (i.e. for use when eastern king prawn – Melicertus plebejus – is the primary target species). However, industry concerns over this design have to date prevented its implementation. Here, using direct twin-tow comparisons onboard a subset of the fleet, we quantitatively assessed the performance of the square-mesh codend, relative to the range of diamond-mesh codend designs currently being used, in terms of reductions in bycatch rates and shortfalls in catch rates of retained animals. Generalised linear mixed-effects modelling across all vessels showed that when eastern king prawn was the target species, the square-mesh codend significantly reduced bycatch rates (by ∼48%), but with an accompanying significant shortfall in catch rates of eastern king prawn (∼7%) and a substantial (though not statistically significant) shortfall in catch rates of an important component of the retained byproduct (whiting, Sillago spp., ∼36%). Partitioning of data by vessel revealed that such shortfalls in retained catch were evident for only some vessels, while the square-mesh codend performed as intended for the others. When school prawn (Metapenaeus macleayi) was the target species, substantial shortfalls in catches of school prawn (∼54%) in the 35-mm square-mesh codend confirmed that a codend of a smaller square mesh might be a more appropriate design under those circumstances. Potential strategies to address intra-vessel inconsistencies in performance of the square-mesh codend and thereby facilitate implementation of square-mesh codends in the fishery are discussed.

We introduce the concept of universal microwave photonic processor as opposed to the current application specific paradigm. We then explore the use of the hexagonal and square mesh topologies for the implementation of versatile and programmable optical cores for MWP processors.

Link to publishers version: 10.1371/journal.pone.0160354 It is well established that increasing mesh number in the circumference of a diamond-mesh trawl codend can reduce size selection for round fish, whereas selection for flat fish species is unaffected. This effect has also been documented in Mediterranean trawl fisheries. In contrast, no information is available with regard to the effect of increasing mesh number in the circumference of square-mesh codends on the size selection of round fish and flat fish species. A field study was devised to bridge this gap and formulate proposals aimed at improving trawl fishery management. Size selection data were collected for a round fish species, red mullet (Mullus barbatus), and two flat fish species, Mediterranean scaldfish (Arnoglossus laterna) and solenette (Buglossidium luteum). Fishing trials were conducted in the Adriatic Sea (Central Mediterranean) using three square-mesh codends that differed only in mesh number around the circumference. Results demonstrated that increasing the number of meshes from 107 to 213 reduced the 50% retention length (L50) for red mullet by 2.5 cm but did not affect size selection for the two flat fish species. In some fisheries, regulatory provisions regarding the number of meshes in the circumference should therefore be carefully considered both for diamond- and square-mesh codends.

The study was conducted among the large mechanised wooden trawl boat operators involved in marine fishing in three selected major fishing harbours of the country viz ., Visakhapatnam in Andhra Pradesh, Thoothukudi in Tamil Nadu and Veraval in Gujarat. The socio-economic and psychological characteristics of fishermen were assessed. The overall innovation decision efficiency index (IDEI) score was 55.25%. The findings on centre-wise and technology-wise IDEI scores are also discussed. The respondents from the three fishing centres differed significantly (p

[EN] We propose and analyse two novel mesh design geometries for the implementation of tunable optical cores in programmable photonic processors. These geometries are the hexagonal and the triangular lattice. They are compared here to a previously proposed square mesh topology in terms of a series of figures of merit that account for metrics that are relevant to on-chip integration of the mesh. We find that that the hexagonal mesh is the most suitable option of the three considered for the implementation of the reconfigurable optical core in the programmable processor., The authors wish to acknowledge the financial support given by the Research Excellency Award Program GVA PROMETEO II/2013/012, Spanish MINECO projects TEC2013-42332-P PIF4ESP, TEC2015-69787-REDT PIC4TB and TEC2014-60378-C2-1-R MEMES, as well as the projects FEDER UPVOV 10-3E-492 and FEDER UPVOV 08-3E-008. The work of D. Perez was supported by the FPI-UPV Grant Program from the Universitat Politecnica de Valencia and the work of I. Gasulla was supported by the Spanish MINECO through the Ramon y Cajal Program. R. Soref is supported by the Air Force Office of Scientific Research.

Summary The size selectivity of alternative codends for nylon shrimp and yellow squat lobster was studied off the Chilean coast using the covered codend technique. Various mesh sizes (47 and 63 mm mesh opening) and shapes (diamond and square) in the codends were used. For both species, substituting the DM47 codend with the DM63 codend significantly increased 50% retention length (l50). The change of diamond (DM47) to square mesh (SM47) had a positive effect in size selectivity for nylon shrimp. For yellow squat lobster, no significant effect was observed when changing the diamond (DM63) to square mesh (SM63). Selectivity data were modeled by considering explanatory variables such as ‘codend catch weight’ and ‘vessel’. Increases in the catch significantly reduced the l50 for both species whereas the vessel factor was not significant. Finally, using the length at first maturity as a reference value, the authors concluded that the DM47 codend failed to protect the immature portion of either stock, thus the DM63 codend is recommended.

Türkiye trol balıkçığında 44 mm baklava gözlü torbaya bir alternatif olarak 40 mm kare gözlü torbanın kullanımı Eylül 2008’de kabul edilmiştir. Buna ilaveten, Avrupa Birliği tüm Akdeniz için bu göz açıklığı ve şeklinin kullanımını teklif etmiştir. Bu nedenle çalışma Ege Denizi’nde çok türün avcılığının yer aldığı demersal trol balıkçılığında farklı iki göz şekli ve açıklığındaki torbanın ıskarta özelliklerini karşılaştırmayı amaçlamıştır. Denemeler, Ege Denizi’nin Sığacık ve Kuşadası Körfezlerinde 30 Eylül - 25 Ekim 2007 tarihleri arasında ticari bir trol teknesi ile yürütülmüştür. Hedeflenmeyen türlerin miktarı, ıskarta av artı tesadüfi av ve ıskarta oranı ise yakalanan miktarın ıskartaya oranlanması ile tanımlanmış ve hesaplanmıştır. Çalışma süresince 21 geçerli trol operasyonu gerçekleşmiş, 53 tür yakalamış ve bunlardan 11’i güverte üzerinde alıkonulmuştur. Iskarta oranı baklava gözlü torba (44 mm) için 0,42:1 ve kare gözlü torba (40 mm) için 0,25:1 olarak hesaplanmıştır. Baklava ve kare gözlü bu torbalar için toplam avın sırasıyla %30’u ve %20’si pazar değeri olmadığı için ıskarta edilmiştir. Bu çalışmanın sonucunda, demersal trol torbasında kare gözlü ağların kullanımının ıskarta miktarını düşürdüğünü açığa çıkarmıştır. Akdeniz balıkçılığının kendine has özelliklerini de göz önünde bulundurarak, balıkçılık kaynaklarının sürdürülebilir işletimini sağlamak için ağ göz şekli gibi ilave teknik düzenlemelerin uygulamaya alınması faydalı olacaktır

Summary Differences in size selectivity of commercial (40 mm diamond mesh, 40D), larger mesh (48 mm diamond mesh, 48D), and square mesh codends (40 mm square mesh, 40S) for hake (Merluccius merluccius), greater forkbeard (Phycis blennoides), blackbelly rosefish (Helicolenus dactylopterus dactylopterus) and four-spot megrim (Lepidorhombus boscii) were investigated in the Aegean Sea. The study was conducted using the covered codend method. Data were analysed taking between-haul variations into account. Results showed that changing from a 40D to 48D codend significantly improved mean L50 values, with increases of about 22% for hake, 8% for greater forkbeard, 20% for blackbelly rosefish, and 11% for four-spot megrim (P = 0.000). A change from diamond to square mesh configuration with the same 40 mm netting also significantly increased the mean L50 values, with 45% for hake, 36% for greater forkbeard, and 25% for blackbelly rosefish (P = 0.000). For four-spot megrim the mean L50 value was about 10% lower, but this difference was statistically insignificant (P > 0.05). Despite the increases in L50 values, this study concludes that the selectivity of the 48D and 40S codends is still not sufficient to release fish smaller than length at first maturity for these four species.

In the past, experimental fishing with square mesh codends was conducted with the expectation that this would lead to a better defined size selection indicated by a smaller selection range (SR) of haddock ( Melanogrammus aeglefinus ) and other gadoid species compared to that provided by traditional diamond mesh codends. However, experimental results demonstrated considerable between-haul variations in the selection parameters (L50 and SR). It was speculated that these results could be linked to differences in morphology of individual haddock of the same length. In the present study we assessed which measures of haddock morphology are important for size selection through meshes. We quantified between-individual variation in morphology and used simulation techniques to estimate that this variation can account for less than 28% (range 15–28%) of the SR values found during experimental fishing. By including a realistic range of mesh openings when simulating the fishing process of a square mesh codend, we were able to explain most of the experimental results. Additionally, we used our method to better understand the seasonal variation in size selectivity reported in the literature and to predict the basic selective properties for haddock for other mesh shapes. Finally, we found that the conditions of our model, which describes mesh penetration for haddock based on assessment of morphology, is very similar to the conditions previously applied in the literature to study size selection of haddock in diamond mesh codends.

Codend selectivity for the jack mackerel Trachurus japonicus and the whitefin jack Kaiwarinus equula were evaluated based on data from trouser trawl experiments carried out in the East China Sea, using a test codend of 60 mm diamond mesh and a control codend made of minnow net with a square mesh of 9 mm bar length. Between-haul variations in parameters and the mean selection curves were tested with the catch data in the SELECT approach, and then the model of between-haul variation in the split parameter with the mean selection curve was chosen as the best fit using Akaike’s information criterion model selection. The 50% retention lengths and the selection ranges were 11.4 and 3.36 cm for jack mackerel and 8.83 and 0.93 cm for whitefin jack, respectively. The selection curve for whitefin jack was sharp, whereas that for jack mackerel was relatively wide. As the estimated split parameters indicated, about 80% of the whitefin jack entered the control codend, but 85 and 90% of the jack mackerel entered the control codend in the second and third hauls, respectively. The inequality in the split parameter is discussed from the viewpoint of the animal’s swimming behavior and water movement based on underwater video observations.

The selectivity characteristics of 4 juvenile fish escape panel designs and their utility for the regulation of a multi-species demersal trap fishery were evaluated using a suite of objective socio-economic and biological criteria. The panel designs consisted of a control (type A) which had a hexagonal mesh size which was the same as that of the body of the trap (3.5 cm), a rectangular mesh (type B) which was representative of the current regulation (5.0 x 7.6 cm) and 2 escape panels with square meshes of 7.5 x 7.5 cm (type C) and 10.0 x 10.0 cm (type D). The results demonstrated that there was only a limited reduction in the proportion of juvenile fish and by-catch retained for the existing juvenile escape panel design (type B). Furthermore, as the selectivity characteristics for the key species (Epinephelus coioides and Diagramma pictum) were similar to the control type, the predicted increases in yields, revenues and spawning stock biomass were small by comparison. The escape panel with the largest mesh size (type D) retained the least un-utilized and discarded by-catch. Whilst simulations predicted the highest spawner biomass per recruit, long term yields and revenues for the key species, its use was associated with a dramatic short-term decline in revenues which were 23.3% of the value of the control type. Traps fitted with the type C which had a square mesh of 7.5 x 7.5 cm had the lowest juvenile retention and the highest overall score for all the assessment criteria combined. The study provides an empirical basis for gear regulations for the demersal trap fishery of the Emirate of Abu Dhabi and the wider Arabian Gulf region.

Two sets of trials were conducted, on the west and east coasts of Scotland, to estimate the selectivity of an 80 mm diamond mesh codend fitted with (i) a 35 mm Swedish grid, (ii) a 120 mm square mesh panel (SMP) at 6–9 m from the codline and (iii) a 120 mm SMP at 12–15 m from the codline. The main results can be summarised as follows: • the Swedish grid gear retained all Nephrops • the SMP gears retained between 70 and 88% of Nephrops below about 37 mm and all Nephrops ≥ 40 mm; • the grid gear retained fewer whitefish than the SMP gears. No cod > 34 cm, haddock > 35 cm, whiting > 38 cm and hake > 41 cm were retained by the grid gear; • and the position of the SMP had no significant effect on the retention of Nephrops, cod, haddock, or whiting.

The relationship between the amount of square mesh in codends and selectivity was investigated for an Australian penaeid stow-net fishery. Three lengths (3, 2 and 1 m) of square-mesh codend made from 27-mm mesh hung on the bar were alternately tested with a conventional 34-mm diamond-mesh design during two covered-codend experiments. Compared with the conventional codend, the square-mesh configurations incrementally selected school prawns, Metapenaeus macleayi (Haswell) across narrower selection ranges (SR) and mostly at greater sizes at 50% retention (L), while retaining fewer fish. Irrespective of the mesh configuration or square-mesh codend length, there were significant differences between experiments (attributed to water flow) and impacts of catch weight on the selectivity of school prawns. Both variables had a negative relationship with L, while water flow similarly affected SR. This study reaffirms the utility of square-mesh codends as a key input control for managing the selectivity of penaeid-catching gears.

This study was predicated by a recent management proposal to mandate square-mesh codends in an Australian estuarine squid trawl fishery, based on their improvements to the selectivity of penaeid trawls deployed across comparable temporal and spatial scales. The assumption of no impacts of a codend cover on the performance of a squid trawl was validated before it was used to quantify the size and species selection of a conventional codend made from 41-mm diamond-shaped mesh and two new designs made from 29- and 32-mm mesh hung on the bar (i.e. square shaped). Compared to the 41-diamond codend, both square-mesh designs incrementally and significantly reduced the catches of a small legally retained teleost (whitebait Hyperlophus vittatus), but had no significant effect on discarded catches (termed ‘bycatch’). The 32-square codend also significantly increased the sizes at 50% probability of retention for the targeted squid (Luminous Bay squid Loliolus noctiluca and broad squid Photololigo etheridgei), across narrow selection ranges and, because all sizes are retained, consequently reduced their total landed catches. The results support the utility of square-mesh for consistently improving and maintaining lateral openings in codends, but the management of this fishery means that such configurations would result in economic loss, and for the 29- and 32-square codends, no concomitant reduction in bycatch. This study reiterates the need for bycatch issues to be clearly identified and defined on a fishery-specific basis, and prior to the implementation of mitigation measures.

The survival of fish discarded after being caught can be improved by simple gear-based technical measures aimed at reducing discards. We look at the effects of three different codends on the initial health and short-term survival of trawl-caught skate (Rajidae), using a control codend (80 mm diamond mesh used as standard in the fishery) and two experimental codends (100 mm diamond mesh and 100 mm diamond mesh turned on the square). Both experimental nets reduced discarded numbers of fish by ~70%, with no commercial loss. This reduction in discards had an effect in reducing the total weight of the experimental codends by as much as 80%. We also placed 278 skate in onboard holding tanks for 48 h and evaluated the survival rates of fish caught in the different codends. Visual inspection of "health" at time zero was a good indicator of survival, because 86% of skate with a good health score survived (p < 0.01). From a further 1539 skate assessed for health, we show that fish caught in the control codend have the lowest proportional good health score (25%), followed by the 100 mm diamond mesh codend (34%) and the 100 mm square mesh codend (47%). The health of the fish caught is related to codend weight (p = 0.01). We conclude that technical measures aimed at reducing discards have an additional benefit; they indirectly increase discard survival, and the benefits of mitigating discards through by-catch reduction devices may be a more powerful tool in fisheries management than previously thought.

日本海西部海域の沖合底曳網で，現在の菱目網（目合内径 33 mm）コッドエンドと，その前半部の両脇部か天井部あるいは両方に角目網（目合内径 72 あるいは 81 mm）を装着した選別式コッドエンド，菱目網（目合内径 79 mm）コッドエンドを用いて，カバーネット操業実験を行った。標本抽出率を考慮した SELECT 解析によりアカムツとマアナゴに対する選択性曲線を推定した。選択性曲線における曳網間の変動は大きいが，平均的な選択性曲線を比較すると，アカムツは天井部から，またマアナゴは両脇部から抜け出やすい傾向がある。

This study illuminates a range of technological options relevant to present legislation for regulating fish by-catch in a small-meshed Nephrops fishery. The selection of cod, haddock, hake, lemon sole, Nephrops , plaice, saithe, witch, and whiting were evaluated using the twin-trawl technique for: (i) a 90 mm diamond mesh codend (standard codend); (ii) a standard codend with a 120 mm square mesh panel (SMP); and (iii) a standard codend with a 35/80 mm grid mounted in the extension piece to hinder access to the codend for large individuals. We used selection models to estimate selection parameters by species and confidence bands to compare the selective properties of different gear types. For cod, haddock, hake, Nephrops , plaice, and whiting we obtained estimates for all three gear variants, whereas we obtained estimates for lemon sole and witch only with the standard and the SMP codends and for saithe only for the SMP codend. The SMP significantly ( p Nephrops .

We describe how discarding can be significantly reduced by incorporating some simple gear modifications to a beam trawl. These modifications were developed by the fishing industry in response to public concerns on the relatively high levels of discards in their fishery (ca. 70% discard rate). A national competition specifically created to facilitate the engagement of industry successfully resulted in the development of these gear-based discard solutions. The modifications produced discard reductions of around 60% (by number) and have been used on a continuous commercial basis for more than a year by the competition winner. All beam trawls used in the UK beam trawl fleet are similar in design, but we demonstrate that the modifications outlined here may not be universally acceptable across the whole beam trawl fleet, primarily because of the diversity in species targeted. This supports the idea that vessel-based discard mitigation targets might be a more effective tool than prescriptive gear technology legislation in the management of discard reduction.

Broadhurst, M. K., and Millar, R. B. 2009. Square-mesh codend circumference and selectivity. – ICES Journal of Marine Science, 66: 566–572. Despite the wide-scale assessment and the use of square-mesh codends in demersal trawls, relatively few studies have tested the effects of configurations other than mesh size on their selectivity. We investigated the consequences of increasing the circumference of square-mesh codends used in an Australian penaeid fishery from the expected optimal configuration of ∼33% of maximum diamond-mesh extension to ∼56 and 75%. Three square-mesh designs comprised 27-mm polyamide mesh throughout and had the same length (100 bars, B), but different circumferences (90, 150, and 200 B, respectively). Paired simultaneous comparisons (using twin trawls) of each treatment codend against a small-meshed control revealed significant effects of circumference on the efficiency of the trawl for a small teleost (pink-breasted siphonfish, Siphamia roseigaster) and commercial size classes of school prawns (Metapenaeus macleayi). Compared with the 90 codend, pink-breasted siphonfish catches and prawn count (numbers per 500 g) were both significantly greater in the codends of larger circumference, and these effects are attributed to concomitant (i) convoluted or reduced lateral openings of meshes and (ii) lesser probabilities of organisms encountering meshes in the posterior section. These differences would not preclude the use of codends of larger circumference in the fishery, but they do highlight the need to select appropriate configurations in future studies to reduce the potential for including the confounding effects of different geometries.