Hook Size Research Articles

Longline Hook Selectivity for Branchiostegus japonicus (Houttuyn, 1782) and Dentex tumifrons (Temminck & Schlegel, 1843) in the East China Sea

Bottom longline fishing of red tilefish (Branchiostegus japonicus) is one of the most important commercial of fishing in the East China Sea. The present study aimed to investigate hook selectivity in B. japonicus and D. tumifrons, by means of experiments using three hook sizes (“J”: #15, #13 and #11) and was conducted in the East China Sea from June to August 2018. Altogether 602 B. japonicus fish and 858 D. tumifrons fish were caught. With respect to the size of the hook used, the total length-frequency varied significantly for both B. japonicus and D. tumifrons that were caught. The total length and four mouth parameters (upper and lower jaw length as well as height and width of mouth opening) of the two species showed a positive linear relationship. A logistic model created using the maximum likelihood method was used for elucidating hook selectivity; the best fit model with the minimum Akaike’s Information Criterion value was selected as the final model. The 50% selection lengths were 224.827 and 233.179 mm for B. japonicus; 201.461 and 202.603 mm for D. tumifrons using “J” #13 and “J” #11 hooks, respectively. To preserve the reproductive potential of younger fish in the stocks, the size of the “J” #13 hook was selected as the minimum hook size that should be used for the sustainable development of bottom longline fishing for B. japonicus and D. tumifrons.

Effects of leader type and gear strength on catches of coastal sharks in a longline survey around Bimini, The Bahamas

Our study assessed the influence of leader type (monofilament vs stainless steel cable) and gear strength (i.e., hook size and leader thickness) on species composition, catch rates, and size distribution of sharks captured in a fisheries independent longline survey near Bimini, The Bahamas. A total of 28 surveys were conducted, resulting in 50,400 hook hours. Catches consisted of 167 sharks from eight species. Overall, catches were higher on monofilament leaders for light duty gear, but there was no difference for heavy duty gear. When bite-offs were combined with catches to form ‘total shark contacts’ the rates were not significantly different between the two leader types. Tiger sharks were the only species to show differences in mean pre-caudal lengths between light and heavy duty gear, likely due to the wide range of size classes encountered for this species. These results further highlight the importance of understanding selectivity of terminal gear (gear strength and leader material), especially for comparing catches across surveys conducted by multiple agencies or organizations.

Multispecies selectivity of line fishing towards sustainability

Understanding the selectivity of demersal fish towards different fishing methods is an important contribution to generate fisheries management plan. The purpose of this study is to examine the selectivity of line fishing on reef fishes based on multispecies approached. Coral fishes were caught by hand lines, longlines and trolled lines by fishers from Kotania bay, Maluku-Indonesia. The species and size of fish catch from January 2013 to December 2014 was filled in logbooks. Multispecies selectivity was estimated by the abundance size spectrum according to methods of fishing: handline, longline and trolled line. In total, 30886 reef fishes were collected, representing 147 species and 37 families. By grouping into genus, longline captured 55 genus which selective to genus Epinephelus, Handline caught 54 genus targeting on genus Lethrinus and trolled line caught 24 genus which selective to genus Plectropomus. Size distribution by hook sizes were not normally distributed (P < 0.001). Multispecies approach from multi-gear selectivity analysis resulted that trolled line was the high selective method especially for grouper family. Handline showed equal selectivity among species captured while the selectivity of longline was varied among fish. Fishing method, hook sizes and biodiversity are the important factors affecting multispecies selectivity. Knowledge of multispecies selectivity is important for fisheries management and fishing allocation in supporting balance fishery is recommended to maintain fisheries sustainability.

Efficacy of dehooking tools for the removal of hooks from the jaw region of angled fish

There are a variety of tools that have been developed to aid in hook removal of angled fish that are intended for release. The premise of these tools is that they enable rapid hook removal while causing negligible injury to fish. Here we scientifically assessed the efficacy of dehooking tools for the removal of single barbed J-hooks from the jaw region (i.e., shallowly hooked) of smallmouth bass (Micropterus dolomieu). Specifically, we compared dehooking time and physical injuries caused by using bare hands, hemostats, pliers, a push-pull device, and a mechanical dehooking device. Bare hands yielded the most rapid dehooking time and the least injury. Dehooking times were the longest for push-pull and mechanical dehooking tools. Moreover, those two purpose-built tools caused the most injury, including tissue tears and bleeding. Dehooking times were intermediate for hemostats and pliers, and they yielded injury similar to use of bare hands. Overall, there was no evidence of conservation benefit arising from use of dehooking tools with smallmouth bass caught on single barbed J-hooks. However, there are other contexts where they may be use useful, such as dehooking sharp-toothed fishes, and if fish are hooked in areas other than the jaw. This research suggests that dehooking tools are not universally useful to achieve optimal catch-and-release outcomes and their utility likely depends on context. Given the wide diversity of fish caught by recreational anglers, as well as the diversity and sizes of hooks, more research on hook removal tools is needed.

Three new species of 'tetraphyllidean' cestodes from an undescribed bamboo shark (Orectolobiformes: Hemiscylliidae) in Sri Lanka.

Examination of seven specimens of an undescribed species of bamboo shark (Orectolobiformes: Hemiscylliidae), currently referred to as Chiloscyllium sp. 1, from Sri Lanka yielded three new species of 'tetraphyllidean' cestodes, one each in the genera Carpobothrium Shipley et Hornell, 1906, Spiniloculus Southwell, 1925, and Yorkeria Southwell, 1927. Carpobothrium marjorieae Caira, Otto et Jensen sp. n. differs from its three valid congeners in total length, number of testes, and size of the apical sucker of its anterior bothridial flap. Like Carpobothrium eleanorae Koontz et Caira, 2016 it possesses spherical eggs with highly elongate bipolar filaments, but its eggs are conspicuously larger than those of the latter species. Spiniloculus akshayi Caira, Otto et Jensen sp. n. can be distinguished from its five congeners in total length and number of proglottids. Yorkeria sachiniae Caira, Otto et Jensen sp. n. differs from its 16 congeners in number of proglottids and testes, total length, terminal proglottid, cirrus sac, and cephalic peduncle length, hook size, genital pore position, and bothridial shape. The eggs of Y. sachiniae Caira, Otto et Jensen sp. n. are spindle-shaped and bear a single long, polar filament. All three species were found to exhibit microthrix patterns on their scolices like those of the majority of their congeners that have been examined to date with scanning electron microscopy. Microtriches on the distal surfaces of the bothridial pouches of a species of Carpobothrium were characterised for the first time; C. marjorieae Caira, Otto et Jensen sp. n. was found to possess a modified form of gladiate spinithrix on this surface. Among the seven members of the genus, this is the first species of Chiloscyllium Müller et Henle that has been found to host representatives of all three of these 'tetraphyllidean' genera. However, unlike most of its congeners, a representative of the non-hooked genus Scyphophyllidium Woodland, 1927 was not found infecting Chiloscyllium sp. 1.

Investigation of the Effects of Hook Size and Bait Type on the Catch of Whiting, Merlangius merlangus (Linnaeus, 1758) (Gadidae) in Bottom Longline Fisheries of the Black Sea

This study was carried out along the Ünye coasts of the South-eastern Black Sea (Turkey), in order to investigate the effects of hook size and bait type on the catch of whiting, Merlangius merlangus (Linnaeus, 1758) (Gadidae) in the bottom longline fisheries. For this, a set of bottom longline with a total of a hundred hooks, including 20 from each hook number 2, 4, 6, 8 and 10, was tested in a total of 24 trials twice a month between March 2017 and February 2018. Each hook type was baited with squid, horse mackerel, chicken breast and whiting. During the study, a total of 373 whiting were caught. Most of the whiting catch was obtained with the hook no 2. With the reduction in hook size, both the amount of catch and the size of the fish caught decreased. Most whiting werecaught by the hooks baited with squid. This was followed by the hooks baited with horse mackerel, chicken breast and whiting, respectively. This result shows that hook size no 2 or larger should be used for catching whiting when using bottom longline in the Ünye coasts of the South-eastern Black Sea. Howev-er, considering the bait types used in this study, it is recommended to use squid as bait. If squid is thought to increase the cost of fishing, alternatively horse mackerel or chicken breast can also be used as bait.

Investigations on the material flow and the role of the resulting hooks on the mechanical behaviour of dissimilar friction stir welded Al2024-T3 to Ti-6Al-4V overlap joints

During friction stir lap joint welding, hooks are systematically formed at the interface of dissimilar Al2024/Ti-6Al-4V plates. Various hooks dimensions and shapes are observed according to the welding parameters (welding speed, rotational speed and double-pass). Based on digital image correlation (DIC) during tensile shear tests, it is found that hooks features govern the fracture behaviours and, hence, the mechanical properties of the overall welds. In particular, three fracture behaviours are obtained: at the interface, in the Al2024 and across the Ti-6Al-4V plate, which was never reported in dissimilar Al/Ti studies. The aims of this work are (i) to study the influence of FSW parameters on the mechanisms of hooks formation and (ii) to understand the role of both AS and RS hooks on the mechanical behaviour of the welds, by the means of two new approaches. First, hooks are investigated by X-ray tomography which provided some innovative insight into the material flow (3D viewing). Based on these qualitative and quantitative results, hooks are used as tracers and two new scenarios of AS and RS generation are proposed. Then, the contribution of both hooks on the stress distribution is clearly revealed by some calculations of the stresses reached around AS and RS hooks. Contrary to RS hook, AS hook is sharp and, hence, the stress reached at the top of AS hook is characterized by a stress concentration. The results showed that the fracture behaviours are greatly influenced by hooks size and the formation of microstructural defects inside the Ti-6Al-4V, which depend on the welding parameters. In conclusions, this work revealed the relationship between the achievable parameters, the resulting hooks dimensions and the fracture behaviours. In addition, based on the understanding of the material flow, another FSW parameters are proposed to optimize the mechanical properties.

Redescription and molecular analysis of Pallisentis (Pallisentis) nandai Sarkar, 1953 (Acanthocephala: Quadrigyridae) in India.

Pallisentis (Pallisentis) nandai Sarkar, 1953 is a freshwater fish parasite restricted to the Indian subcontinent in the Ganga River and its tributaries. It was described from the leaffish, Nandus nandus (Hamilton) from the Ganga River delta at Calcutta. We recovered variant specimens from the same host species from the Ganga near its headwaters at Bijnor about 1500 km away. Our specimens were clearly identifiable as P. nandai but varied considerably from those in the original description, especially in the size of proboscis hooks, receptacle and lemnisci. The original description was incomplete (missing line drawings of female trunk and reproductive system, male trunk, complete proboscis, hooks and hook roots) and inaccurate (proboscis, hooks, receptacle wall), and some measurements were lumped together for both sexes. We provide a complete description and include new morphological information including the first description of para-receptacle structure in the genus Pallisentis Van Cleave, 1928, scanning electron microscopy and microscope images, molecular analysis, and energy dispersive X-ray analysis (EDXA) of hooks and spines of our specimens for the first time. Additional details of proboscis hook roots, trunk spines, micropores and micropore distribution are described. The unique metal composition of hooks (EDXA) demonstrated a considerably high but variable level of sulphur and negligible level of calcium in collar and trunk spines and hook tips, but a higher level of sulphur and calcium at the hook basal arch than at the hook tip and edge. A comparison with the EDXA pattern of another species of Pallisentis, P. İndica Mital & Lal, 1976, were considerably different. The phylogenetic position of P. nandai within Eoacanthocephala was generated to assess the molecular characterization based on 18S and ITS1-5.8S-ITS2 ribosomal DNA sequences. Maximum likelihood and Bayesian inference analyses placed P. nandai in a clade with other Pallisentis species under the family Quadrigyridae. This is the first report based on molecular evidence for P. nandai.

Lossless Image Compression Using Wavelet and Vector Quantization.(Dept.E)

In this paper, we propose a new low bit rate scheme that combines the Discrete Wavelet transform (IWT) and Vector Quantization (VQ) for image compression with high Compression Ratio (CR) in order to achieve acceptable quality of output images, Image compression using the combination of DWT willy VQ has been considered in many recent works; here in our paper the DWT was performed on several gray scale standard images, each of (256X256) byte. We used 4 images as the training images of the train VO using LBG algorithm and got the final optimal codebook. Then we used another two images to compare our output image with JPEG 2000 standard winch based on Wavelet and Scalar quantization. Our proposed system used a VO codebook with Variable cod hook size and dimensions were used to compress wavelet Transform) coefficients resulting using Danny wavelet types. Our pro system is slowed so that the best Wavelet types that you can use for compression is COIF 2. Our proposed system gave better PSNR than G2000 standard at high (CR), above than (5L), and this achieved a VQ codebook size (1024 -512) with dimension equal to 256. In the paper a typical system for the application of image compression system and new scientific results are present.

Hook selectivity and catch efficiency in two sport fishing sectors in the Strait of Istanbul, Turkey: Classic handline fishing and Light Rock Fishing (LRF)

In this study, the efficiency of two fishing methods (a) traditional handline commonly used in the Strait of Istanbul and (b) light rock fishing (LRF), which is beginning to spread in recent years, were investigated by monthly sampling between September 2014 and September 2015. One classic handline fishing tackle and one LRF fishing tackle were used in the test fishing exercise. In addition, the effects of the hook sizes (numbers 6, 8 and 10) used in the handline fishery on the size selectivity for horse mackerels were also studied. Catches using both types of fishing gear were mainly composed of Trachurus mediterraneus (89.60%), Scorpeana porcus (5.12%), Sardina pilchardus (1.98%), Atherina boyeri (0.99%), Liza aurata (0.66%), Scorpaena scrofa (0.50%), Pomatomus saltatrix (0.33%), Sprattus sprattus (0.33%) and a few other species. The frequency distributions of horse mackerel caught using handlines and LRF were slightly different and ranged between 6.1–19.0 cm and 9.0–16.0 cm, respectively. Of all the handlines, LRF yielded the highest catch per unit effort (CPUE), 1.295 kg/10 hooks/hour. The log normal model selectivity curve gave the best fit for the T. mediterraneus by using the SELECT method. The modal lengths of horse mackerel caught by handline hook sizes no.10 and no. 8 hook were calculated as 13.4 cm and 17.7 cm, respectively. In addition, the spread values were determined with 3.58 and 4.74, respectively.

Deconstructing size selectivity to evaluate the influence of fishery management

Fisheries are managed through various means to regulate harvest and maintain the sustainability of the stock. These regulations also influence which size fishes are removed from the population: A minimum mesh or hook size directly affects the size of fish retained by the fishing gear. A minimum fish size leads to discards, and any survival of released fish decreases the selectivity for sub-legal size classes. Closed areas and seasons indirectly influence size selectivity by altering the relative availability of each size class. Collectively, these regulations control the population-level size selectivity of the fishery, which is the product of gear selection (modulated by discard mortality) and spatiotemporal availability. Stock assessment models are particularly vulnerable to incorrectly specified selectivity, yet it is difficult to independently validate the structure of this variable because it is influenced by several processes. We analyzed the Gulf of Maine fishery for Atlantic cod (Gadus morhua), which has been intensively regulated through a complex management system for several decades, and deconstruct the mechanisms through which regulations have influenced fishery selectivity. Gear selection-at-size was estimated for four fleets under two regulatory regimes by comparing the size distribution of survey and fishery catches, sampled from the same time and area. Availability-at-size was estimated by weighting predictions from a random forest model of fish density-at-size by the spatiotemporal pattern of fishing effort. Several regulations caused fishery selectivity to be distinctly dome-shaped, and regulatory changes altered the shape of this curve over time. The approach of deconstructing selectivity into its gear and availability components can be adapted to other stocks to elucidate the underlying mechanisms, inform assessment models, and evaluate alternate regulation scenarios.

Do angler experience and fishing lure characteristics influence welfare outcomes for largemouth bass?

Catch-and-release (C&R) angling is common with anglers releasing a portion of their catch to comply with harvest regulations or because of their conservation ethic. The basis of C&R lies in the assumption that a large proportion of the fish survive and experience limited fitness consequences – that is, the welfare status of individual fish is maintained. However, the level of experience of an angler, as well as use of different gear and lure types, can greatly influence the rate of hooking injury and mortality. These relationships have been documented for a variety of fish species, but few studies have considered the influence of both angler experience and gear or lure type simultaneously. The aim of this study was to evaluate the relationships between angler experience, lure characteristics, landing time, hooking injury, and handling time in the Largemouth Bass (Micropterus salmoides). Largemouth Bass were captured by hook and line between July and September 2018 by anglers with a wide range of experience (novice to professional). During and after these events, measurements were taken on fish characteristics, angler experience, lure characteristics, and welfare outcomes. Generalized linear models indicated that lure characteristics (lure type, size, and number of hooks) had a significant influence on fish injury and handling time, whereas angler experience did not. Specifically, lures with more hook points resulted in shallower hooking depths but longer dehooking times. These results indicate that lure choice is an important aspect of managing C&R fisheries. When choosing a lure, there may be a tradeoff between minimizing the physiological stress associated with handling and air exposure, and reducing the chances of injury and deep hooking. Additional research is needed to better understand such trade-offs across a range of environmental conditions and species.

Trotline hook selectivity for the Atlantic Bonito (Sarda sarda Bloch, 1793) fishery in the Çanakkale Strait (northern Aegean Sea, Turkey)

Abstract This study was conducted to determine the selectivity of hooks (galvanized, tin, carbon, nickel) used for Atlantic bonito (Sarda sarda Bloch, 1793) in the Gallipoli Peninsula and the Dardanelles during the 2015 and 2018 fishing seasons (spring and autumn). The Atlantic bonito was fished with hooks of size 1/0, 2/0, 3/0, and 4/0. A total of 604 bonitos were caught, including 201 individuals using a galvanized hook, 194 individuals using a tin hook, 158 individuals using a nickel hook and 51 individuals using a carbon hook. A lower catch was obtained with hooks of size 4/0 (42 in total). The highest catch (100 total) was obtained with hooks of size 1/0 and a lower catch (19 in total) was obtained with hooks of size 4/0 in the case of tin hooks. In the case of nickel hooks, the highest catch (63 in total) was obtained with hooks of size 1/0 and a lower catch (eight in total) was obtained with hooks of size 4/0. The optimum catch length and curve width were calculated in relation to the size of hooks. It was determined that all hooks used in the experiments catch below the length allowed for fishing. It was therefore concluded that the use of the largest hooks would be preferable, with size 4/0 being the most suitable for maintaining the continuity of the species.

Assessing the Relative Selectivity of Multiple Sampling Gears for Managed Reef Fishes in the Eastern Gulf of Mexico

AbstractFishery‐independent data are important for the effective management of reef fishes in the eastern Gulf of Mexico. Proper characterization of selectivity, or the effectiveness of each type of sampling gear in capturing a species or a size‐class, is essential to ensure that assessment models treat various sources of data appropriately. In this study, we analyzed fishery‐independent data that was collected using stereo‐baited remote underwater video (S‐BRUV) arrays, chevron traps (TRAP), and two types of hooked gear (repetitive timed‐drop [RTD] and vertical longline [VLL]) to assess gear‐related differences of species composition and size selectivity of managed reef fishes in the eastern Gulf of Mexico. Significant differences were detected in the assemblage structures of reef fishes in relation to region, gear type, and depth. Overall, eight managed species were identified as contributing to the top 70% of the assemblage structure for each gear type. Stereo‐baited remote underwater video had the highest abundances for most of the species and the highest number of species captured, while VLL had the lowest. Two economically and ecologically important species (Red GrouperEpinephelus morioand Red SnapperLutjanus campechanus) were common to all four gear types, and the size selectivity of these two species generally overlapped. However, significant differences among gear types were detected. Unimodal selection curves for hooked gears indicated that size of Red Snapper and Red Grouper increased as hook size increased. These data provide insight on species and size selectivity of multiple gears, which will contribute to future survey design and aid in the management of reef‐fish populations.

Length-weight relationships and condition factor of five marine fish species from Bushehr Province, Persian Gulf, Iran

Length-weight relationships (LWRs) and condition factor were estimated for five economical marine fish species collected monthly using a hand line (hook sizes: 3, 5, 7, 9, and 11) and gillnet (stretched mesh sizes: 13, 14 and 15 cm) in the artisanal vessels from the fishing grounds of Bushehr province located in the Persian Gulf, Iran during October 2018 to June 2019. The LWRs for the fish species were W = 0.0144L3.071 (R2 = 0.99) for S. persicus, W = 0.0329L2.962 (R2 = 0.985) for P. maculosus, W = 0.0275L2.873 (R2 = 0.976) for U. helvola, W = 0.0296L2.867 (R2 = 0.968) for C. chrysophrys and W = 0.0387L2.859 (R2 = 0.982) for P. orbicularis. The estimated range for a was between 0.0144 and 0.0389, and for b was between 2.859 and 3.071. Length and weight ranges for S. persicus (L = 16.2–36.3 cm, W = 84.8-838.5 g), P. maculosus (L = 12.2–48.3 cm, W = 63.7–2648 g), U. helvola (L = 18.9–44.6 cm, W = 124.5-1558.8 g), C. chrysophrys (L = 11.4–67.5 cm, W = 28.5-4935.2 g), and P. orbicularis (L = 17.6–56.2 cm, W = 121.7-3352.4 g) are wider than reported in previous studies. Also, K values were 1.82 ± 0.12 for S. persicus, 2.35 ± 0.11 for P. maculosus, 1.87 ± 0.16 for U. helvola, 1.94 ± 0.23 for C. chrysophrys and 2.29 ± 0.31 for P. orbicularis. The information about LWRs of Scarus persicus and Uraspis helvola are reported for the first time in the Persian Gulf. The results obtained can be beneficial as basic information for fisheries management and improvement of the technical performance of biologists in future studies.

Effect of interfacial characteristics on magnesium to steel joint obtained using FAST

Friction-stir Assisted Scribe Technique (FAST) was used to join AZ31 magnesium alloy to Zn-coated steels including hot-dipped galvanized 590 and electroplated 270 steel with and without coating. The mechanical properties and performance of a FAST joint are governed by its underlying interfacial and microstructural characteristics, which in turn are determined by the FAST tool and process parameters. The FAST tool was utilized to create a different scribe engagement depth that can vary the extent of chemical intermixing and size of mechanical hooks. Microstructure and chemistry investigations on the weld interface were assessed using scanning electron microscopy and electron dispersive spectroscopy. Mechanical properties including lap shear tensile strength and micro and nano hardness at different interfacial regions were correlated to the local microstructures. A finite element-based modeling approach was developed to identify optimal interfacial characteristics that lead to a desired mechanical performance. The results of the computational model were compared to the experimental observations. A sensitivity analysis was conducted to study the variation in the mechanical response and failure modes of the joint with respect to the interfacial characteristics. Results indicate that interfacial characteristics including hook shape can have a significant impact on the joint strength and failure modes.

Simulating effects of hook-size regulations on recreational harvest efficiency in the northern Gulf of Mexico red snapper fishery

Recreational fishers discard millions of red snapper (Lutjanus campechanus) annually in the northern Gulf of Mexico (nGOM), resulting in significant foregone yield. We conducted simulation modeling to evaluate the potential for hook-size regulations to improve efficiency in the recreational red snapper fishery. First, we imposed a suite of candidate parameter sets, informed by recent empirical studies, within the 2015 red snapper assessment model to estimate contact-selectivity of recreational fleets in the northeastern or northwestern GOM. We then evaluated potential hook-size regulations by imposing a suite of candidate parameter sets on future contact-selectivity of each recreational fleet, conditional on likelihood-based estimates from the first simulation exercise. In the assessment model, maximum likelihood values improved when strongly domed contact-selectivity curves with peak size approximating the current minimum length limit were imposed in either the eastern or western recreational fleet. Simulation results indicate mandating large hook sizes could modestly increase retained catch for the eastern recreational fleet while dramatically reducing the number of red snapper discarded by either fleet. Realized benefits of hook-size regulations will depend upon future fisher retention behavior, such as the intensity of live high-grading, discard mortality reduction practices, such as venting and the use of descender devices, and changes to current management regulations.

Maximum Size Record of Sharpsnout Seabream (Diplodus puntazzo Walbaum, 1792) for Saros Bay, Northern Aegean Sea

A single specimen of Diplodus puntazzo with 34.6 cm in total length and 550.00 g in total weight was caught off İbrice Bight (Saros Bay) with handline (hook (Mustad 496) size 1 and 0.40 mm monofilament line-diameter) by fisherman on May 25, 2016. Its total length and weight were the maximum observed values for the species in the Saros Bay, Northern Aegean Sea.

Hook size selectivity in the artisanal handline fishery of Shimoni fishing area, south coast, Kenya

Selectivity of five handline fishing hook sizes was determined following Holt’s 1963 model using data that was collected during January to June, 2016. A total of 966 fish specimens comprising of 65 species belonging to 23 families were sampled. Fish abundance was low for large sized hooks while catch rate was higher. Species diversity was higher during the northeast monsoon season and at the study sites of Mpunguti and Nyuli. However, species diversity decreased with increase in hook size. All hook sizes had a higher selection for mature Lethrinus borbonicus while hook size No. 8 selected immature Lethrinus lentjan. Hook sizes No. 9 and 10 selected mature L. lentjan and Lethrinus rubrioperculatus, hook size No. 15 selected immature L. lentjan, L. rubrioperculatus and Aprion virescens, while hook size No. 16 selected immature A. virescens and L. rubrioperculatus. Species similarity was higher for fish caught by hook sizes No. 16 and 15, and No. 8 and 9, while those captured by hook size No. 10 differed from those caught by other hook sizes. The larger hook size No. 8 is recommended for the sustainable exploitation species in the artisanal handline fishery in Shimoni fishing area. Future work needs to consider the effects of bait type and size and the stock status of the fish under exploitation.

Small-scale fishers’ perception of the implementation of the EU Landing Obligation regulation in the outermost region of the Azores

The archipelago of the Azores (mid-north Atlantic Ocean) is an outermost region of the European Union (EU) in which small-scale fisheries are a strong component of the local economy. Bottom longlining and handlining are the most important Azorean fisheries in landing values, fishing vessels and fishers. Despite their high selectivity and low discards, these fisheries can be highly impacted by the implementation of the Landing Obligation (LO). Semi-structured interviews were conducted with Azorean small-scale fishers to document their perceptions about discards and the LO, and to ascertain the mitigation measures they already implement or could further implement to avoid unwanted catch. Results suggest that most fishers strongly oppose the LO, perceiving it as inadequate to their fisheries. Several discard avoidance measures are already commonly used by most fishers, of which hook size and changing areas where there are too many undersized or over-quota individuals, are believed to be the most efficient. Additional measures to further improve selectivity and avoid unwanted catch appear limited. The recent conversion of many bottom longliners to handlining and the exemptions foreseen as part of the LO for the region might help Azorean fishers to mitigate the potential impacts of the LO.