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Common octopus is a worldwide important cephalopod resource fished by both industrial and small-scale fleets which has gained market value in recent decades. In Galicia (NW Iberian Peninsula), common octopus ( Octopus vulgaris sensu stricto ) has been exploited since ancient times in intertidal and subtidal areas using multiple methods and fishing gears. A vast artisanal fleet using traps has been exclusively dedicated to catching this species since the 1970s. However, a comprehensive description of current fishery dynamics and production is lacking. A total of 1255 vessels had permission to deploy traps in 2016, though effective license usage was considerably lower and has steadily decreased since 2004. The fleet, in recent years, was largely composed of vessels of ∼4.5 t of average gross tonnage (GRT) although the proportion of vessels per GRT segment has changed showing a decrease in vessels of lower and greater segments of GRT, whereas intermediate and more polyvalent segments, mainly between 2.5 and 4.99 GRT, increased notably. On average, the fleet deploys ∼66 traps per haul usually set on a given day and hauled the next one yielding from 0.13 kg trap −1 in the south to 0.25 kg trap −1 in the north. Fishing operations (i.e. number of traps deployed, soak time, fishing depth, and trip length) varied seasonally and along the coast and depended on vessels’ size. Similarly, fishing strategies (i.e. alternation of traps with other gears) also differed along the coastline and during the year. Fishing effort estimated as the number of deployed traps has decreased slightly since mid 2000s and so has expected catches though more pronounced in the northern coast as compared to the south. Furthermore, estimated catches were notably higher than official reported values regardless of the zone. This article provides new insights into the current fishery dynamics of an important small-scale fishery that should be useful for the development and implementation of new assessment and management plans for common octopus in the north-west coast of Spain. [ABSTRACT FROM AUTHOR]

Abstract The United Arab Emirates fisheries consist of highly diverse fish communities, and the most popular equipment used by fishermen to harvest them is a traditional baited basket fishing trap known locally as "gargoor". Gargoors are dome-shaped traps made from galvanized steel; they have a circular supporting base and a funnel-like entrance. Unintended impacts of gargoors on marine fauna include bycatch of non-target species and, when lost, ghost fishing. However, there is very little information on sea turtle interaction with gargoors. In this paper we present two case reports from the eastern coast of the UAE of green sea turtle strandings associated with gargoor interactions. The first case report describes a turtle that was discovered trapped inside a lost or abandoned gargoor. The second case report describes another turtle that suffered from extensive perforation of the gastrointestinal tract resulting from the ingestion of 32 pieces of rusty gargoor fragments. Highlights • Gargoors are dome-shaped fishing traps that are used throughout the waters of the Arabian Peninsula. • We examined two green sea turtle mortalities in the United Arab Emirates that resulted from gargoor interactions. • One specimen drowned from entrapment inside a gargoor • The other specimen suffered from perforations in the gastrointestinal tract from ingesting rusty gargoor fragments. • Our study present two cases of green sea turtle interactions with a regionally popular fishing equipment. [ABSTRACT FROM AUTHOR]

As part of attempts to promote more selective recreational and commercial portunid trap fisheries in south-eastern Australia, the effects of single and multiple rectangular escape gaps (46 × 120 mm) on catches of the targeted giant mud crab, Scylla serrata and incidental species were investigated. Twenty-five collapsible netted round traps comprising five replicates of those with zero (controls), one, two, three or four escape gaps positioned at the base were simultaneously fished in two estuaries by three commercial fishers. Compared to the control, and irrespective of estuary, all traps with escape gaps similarly maintained catches of legal-sized S. serrata (≥85 mm carapace length–CL) while reducing undersize numbers by 85–93%. At one location, 21% of the portunid catch included the smaller blue swimmer crab, Portunus armatus (legal size of ≥60 mm CL); the numbers of which were also significantly lower by 73–96% (across all sizes) in escape-gap traps than the control and with greater escape from traps with multiple escape gaps. Catches of two abundant teleosts were not affected by either single or multiple escape gaps. The results were attributed to species-specific responses to catch densities and while the data reiterate the utility of escape gaps for improving trap selectivity, configurations might need to be fishery specific and/or spatially regulated according to distributions of the key target and incidental species. [ABSTRACT FROM AUTHOR]

Stone-walled intertidal fishtraps surround the Australian coastline and are among the largest structures built by Indigenous Australians. Globally, fishtraps are considered important elements in food production, domestication, territoriality and ceremonial landscapes, yet the level of detail in documentation is highly varied and scholarly fishtrap knowledge sparse. Comparative analysis is currently restricted by a lack of detail and reproducibility in recording, hindering analysis of morphology, function and chronology. In this study we employ high-resolution close-range Unmanned Aerial Vehicle (UAV) photogrammetry and a suite of spatial information analytical techniques to investigate the Kaiadilt Aboriginal stone-walled intertidal fishtraps of Sweers Island, southern Gulf of Carpentaria, Australia. Tidal inundation modelling is undertaken to assess (1) fishtrap working range, (2) individual and simultaneous trap function, (3) seasonal functionality and (4) chronology based on function relative to sea-level history. Thirteen fishtraps were identified in the study area, ranging from 38 m to 287 m in length. Flow accumulation indicates that shape and placement of fishtraps reflects underlying topography. Inundation modelling shows that all fishtraps operate most efficiently at present mean-sea level (PMSL), indicating construction in the last 3500 years. Quantitative recording techniques, analytical procedures and terminology developed in this study provide an opportunity to improve approaches to recording large-scale stone features and standardise documentation of stone-walled intertidal fishtrap sites. [ABSTRACT FROM AUTHOR]

The management of internationally shared fish stocks is a major economic, environmental and political issue. According to international law, these resources should be managed cooperatively under international fisheries agreements (IFAs). This paper studies the formation and stability of IFAs through a coalition game that accounts for both direct consumptive values (harvesting profits) and non-consumptive values of the fish stock per se. The results show that accounting for non-consumptive values helps conserve the fish stock in that equilibrium fishing efforts are smaller and fish stock larger than without non-consumptive values under all possible coalition scenarios (full, partial and no cooperation). However, considering non-consumptive values does not affect the outcome of the game in terms of the prospects for cooperation: even with substantial non-consumptive benefits, the outcome is full non-cooperation. Hence, the trap of non-cooperation in international fisheries management cannot be overcome simply by explicitly accounting for non-consumptive values within IFAs. It is suggested that strengthening the role of IFAs and limiting the ability of non-member countries to free-ride be further investigated as measures fostering cooperation. [ABSTRACT FROM AUTHOR]

Bottom longline hook and trap fishing gear can potentially damage sensitive benthic areas (SBAs) in the ocean; however, the large-scale risks to these habitats are poorly understood because of the difficulties in mapping SBAs and in measuring the bottom-contact area of longline gear. In this paper, we describe a collaborative academic-industry-government approach to obtaining direct presence-absence data for SBAs and to measuring gear interactions with seafloor habitats via a novel deepwater trap camera and motion-sensing systems on commercial longline traps for sablefish ( Anoplopoma fimbria) within Saan inghlas - Bowie Seamount Marine Protected Area. We obtained direct presence-absence observations of cold-water corals (Alcyonacea, Antipatharia, Pennatulacea, Stylasteridae) and sponges (Hexactinellida, Demospongiae) at 92 locations over three commercial fishing trips. Video, accelerometer, and depth sensor data were used to estimate a mean bottom footprint of 53 m2 for a standard sablefish trap, which translates to 3200 m2 (95% CI = 2400-3900 m2) for a 60-trap commercial sablefish longline set. Our successful collaboration demonstrates how research partnerships with commercial fisheries have potential for massive improvements in the quantity and quality of data needed for conducting SBA risk assessments over large spatial and temporal scales. [ABSTRACT FROM AUTHOR]

Abstract: This reports on a project that combined evidence gleaned from aerial photographs, place‐names, interviews, topography, LIDAR data, and sonar bathymetry to locate stone tidal fish weirs in the Molène Archipelago. The results were verified by diver and pedestrian visual surveys. Models of Holocene sea‐level change allowed a group of possibly Late Mesolithic–Early Neolithic weirs to be recognized, with a second group broadly dated to the later Neolithic–Early Bronze Age. The construction of these long megalithic structures is compared to the funerary monuments for which the Molène Archipelago is well known, in terms of technique, cost, and societal organization. [ABSTRACT FROM AUTHOR]

The fishing effort of a Sinaloa crab fishery in the Gulf of California in 2014 was analysed based on fishermen’s interviews, official catches and permits, and information from a sample of fishing logbooks from five fishery cooperatives operating in four coastal lagoons that contained the daily catch from individual fishing trips. Unauthorized gear, a double-ring net (DR), was used most frequently (>70% of the fishers) for crab fishing, although authorized single-ring nets and Chesapeake traps (CT) were also used with low frequency. The estimated fishing effort was 641 boats/day in the four coastal lagoons, which was 34% more than authorized, and 818 boats/day were employed in all of Sinaloa. A total of 57 479 fishing gears were estimated for the study area, which was 49.9% greater than the maximum authorized number, and 80 822 nominal fishing gears were estimated for the entire Sinaloa crab fishery, 14.15% more than the total gear limit (70 800). The size of the mesh used in the gear was smaller than the authorized limit of 76 mm, and >50% of the catches included crabs of unlawful size. It is argued that the effort must be regulated in terms of the number of vessels, per unit time, and not the number of gears. The information from this study demonstrates a failure to monitor compliance with current regulations and thus means that other strategies for the sustainable management of the fishery, such as co-management, should be tested. [ABSTRACT FROM AUTHOR]

The incidental capture of non-target and undersized target species during commercial fishing operations has been identified as a major issue and ongoing challenge for fisheries management. In the Northern Zone rock lobster (Jasus edwardsii) fishery (NZRLF) of South Australia, escape gaps have been mandatory in all commercial fishing traps since 2002 to reduce non-target species (by-catch) catch rates and juvenile lobster mortality. This study usedin situvideo monitoring of by-catch species in traps with and without escape gaps to understand how by-catch species interact within commercial fishing traps. Twenty-two different by-catch species were observed entering commercial rock lobster traps, 20 of which were temperate reef finfish. Overall, on-board by-catch rates were significantly higher in hauled traps without escape gaps and were dominated by reef-dwelling finfish species, particularlyMeuschenia hippocrepisandNotolabrus tetricus. However,in situvideo monitoring within traps showed no difference in the maximum number of finfish by-catch (MaxN) in traps with or without escape gaps. We suggest that the difference in by-catch rates between hauled traps with and without escape gaps may be driven by species-specific behavioural interactions within traps prior to hauling. Overall, this study shows that the implementation of escape gaps in the NZRLF has considerably reduced fishery by-catch rates. Furthermore, the use ofin situvideo monitoring has provided a better understanding of by-catch behavioural interactions within traps, not previously identified in on-board sampling research, which may partly explain the mechanisms underpinning escape gap effectiveness. [ABSTRACT FROM AUTHOR]

The effectiveness of two different funnels such as traps fitted with Oval shaped rear end opening having two different perimeters such as funnels having 560 mm (O1) and 700 mm (O2) were tested. Two sets of traps of funnel each with three chambers were fabricated. The first set of trap was provided with funnels with Oval shaped rear end opening of 560 mm perimeter. The second set of traps had Oval shaped funnel however with the rear end opening perimeter of 700 mm. Fishing trials were conducted in a coastal fishing ground of Mandapam of Tamilnadu (Lat: 09° 14.141'N; Long: 079° 09.433' E). A total of 24 fishing operations were carried. Among two types of funnels, traps fitted with Oval funnel with 560 mm rear end opening perimeter caught more amount of fishes(121 No's/24 soaking days) than the Oval funnel with 700 mm rear end opening perimeter (89 No's/24 soaking days). The study revealed that funnel having oval shaped rear entrance with 560 mm perimeter was superior than the similar shaped funnel having 700 mm perimeter. [ABSTRACT FROM AUTHOR]

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The effects of physical factors on fish catch in the Serbian part of the Danube River were studied for period of six decades. The data on total catch for the Danube River from river kilometre 845 to river kilometre 1433 were collected from Statistical Office of the Republic of Serbia, while water level and water temperature data were collected from 16 water gauge stations along the investigated part of the Danube River for the period 1948–2009. Cross-correlation functions have been used to analyse the functional connection between Danube water level, water temperature and fish catch while ARMA model which combines cyclic (deterministic) and random (stochastic) components of the analysed sequences was used for the forecasts. The cross-correlation function showed negative correlation between water level and temperature as well as between water temperature and catch and positive correlation between water level and catch. The Danube water level and catch were coherent at the periods of 2.06, 4.13, 6.2, 10.33, 20.66 years, while the cross correlation function between these time series did not show phase lag. The results of reconstruction and forecast of water level, temperature, and catch of fish in the Danube River, obtained by summing the cyclic and stochastic components, was used for the forecast till 2029. In 2016, seven years after, the initial forecasts were made, validity of the model was checked by obtaining data for water temperature, water level and fish catch in the Danube River for the period 2010–2015. Model gave the best prediction for water temperature; average standard error was 1.6 times higher for predicted value than for model value while for fish catch and water level they were 1.96 and 4.97, respectively. Methods used in this work could be powerful tool for prediction of fish catch and serve as the basis for better fisheries management. [ABSTRACT FROM AUTHOR]

Crucial to the management of invasive species is understanding space use and the environmental features affecting space use. Improved understanding of space use by invasive sea lamprey ( Petromyzon marinus) could help researchers discern why trap success in large rivers is lower than needed for effective control. We tested whether manipulating discharge nightly could increase trap success at a hydroelectric generating station on the St. Marys River. We quantified numbers of acoustically tagged sea lampreys migrating up to, and their space use at, the hydroelectric generating station. In 2011 and 2012, 78% and 68%, respectively, of tagged sea lampreys reached the generating station. Sea lampreys were active along the face, but more likely to occur at the bottom and away from the traps near the surface, especially when discharge was high. Our findings suggest that a low probability of encountering traps was due to spatial (vertical) mismatch between space use by sea lamprey and trap locations and that increasing discharge did not alter space use in ways that increased trap encounter. Understanding space use by invasive species can help managers assess the efficacy of trapping and ways of improving trapping success. [ABSTRACT FROM AUTHOR]

We estimated the relations between total length (TL) and opercular (Gope) and maximum (Gmax) girths, for the eight most representative lagoon fish species in Mesolonghi-Etolikon lagoons within 2015-2017 (June through December). The following species were studied: Chelon saliens (Risso, 1810); Chelon auratus (Risso, 1810); Chelon ramada (Risso, 1827); Mugil cephalus Linnaeus, 1758; Diplodus puntazzo (Walbaum, 1792); Diplodus sargus (Linnaeus, 1758); Sparus aurata Linnaeus, 1758; Dicentrarchus labrax (Linnaeus, 1758). For five of these species (C. saliens, C. auratus, C. ramada, S. aurata, and D. labrax) LGR estimates were not available. Results showed that both Gope and Gmax increased significantly linearly with TL for all studied species with all r² values being higher than 0.862. When Gmax values were plotted against TL for all species combined, two significant (ANCOVA, P < 0.05) length-girth relations were identified corresponding to different body shapes. The implications of girth measurements for lagoon gear selectivity estimates are also discussed. [ABSTRACT FROM AUTHOR]

Surveys of forensically important insects usually rely on sampling adults on baits – which may not represent the colonizing assemblage on a carcass or cadaver. We investigated the diversity of dipterans (Calliphoridae, Sarcophagidae, Muscidae, Fanniidae) in the Brazilian dry forest, an area exposed to high rates of homicide, under an integrated approach of ecology and forensic entomology. Specifically, we compared the species' ability to colonize different substrates, related to their potential as early carrion colonizers. We used suspended traps baited with fish, feces and bovine spleen to collect adults (visitors) and eggs/larvae on baits (colonizers) and reared immatures in the laboratory until the emergence of adults. Over 30,000 adult flies belonging to at least 30 species were collected on baits, but only 10 species successfully colonized the substrates. Our data corroborate the high diversity of species in the area, especially those with previous record as cadaver colonizers – such as Chrysomya albiceps , Synthesiomyia nudiseta and Tricharaea (Sarcophagula) occidua. Minimum developmental time of the species varied from 9 to 23 days post bait colonization in the field. Blaesoxipha (Gigantotheca) stallengi (Sarcophagidae) was the most efficient colonizer of ephemeral resources in dry forests, and we discuss its potential in forensic entomology. • Brazilian dry forests harbor a high diversity of forensically-relevant Calliphoridae, Sarcophagidae and Muscidae species. • A simplification in the assemblage of dipterans occurs when the diversity of visitors and colonizers is compared. • Blaesoxipha (Gigantotheca) stallengi (Sarcophagidae) is the most efficient colonizer of ephemeral resources in dry forests. • Minimum developmental time of the species varied from 9 to 23 days post bait colonization in the field. • Blaesoxipha (Gigantotheca) stallengi can be a species of potential medico-legal relevance in arid environments. [ABSTRACT FROM AUTHOR]

In this paper, we describe the socioeconomic conditions of the small-scale trap fishery in the Commonwealth of Puerto Rico and examine the determinants affecting the technical performance of the fleet. The socioeconomic data used in the analysis were derived from random, in-person interviews with 50 trap fishers, which accounted for about one-third of the active trap fishers. The study found that the fishery is composed of middle-aged, small-scale commodity producers who use traditional, capital-intensive technologies to target Caribbean spiny lobstersPanulirus argusand various reef fishes. Fishers reported that fishing made up 74% of their household income. We also explored the factors influencing the technical efficiency of the fleet by using a stochastic production frontier model. The analysis suggested that trap operations could increase their gross revenues per trip by 36%, on average, by using current input levels and technology more efficiently. The fleet exhibited decreasing returns to scale. The study also found that a 10% increase in the number of traps tended would raise gross revenues by 0.9% and that baiting traps would raise gross revenues by 1.4%. The analysis suggested that fishing experience and kinship ties were the key determinants of technical efficiency. We also explored the policy implications stemming from these results. Received September 22, 2016; accepted April 6, 2017 Published online June 23, 2017 [ABSTRACT FROM PUBLISHER]

Understanding changes in biodiversity requires the implementation of monitoring programs encompassing different dimensions of biodiversity through varying sampling techniques. In this work, fish assemblages associated with the 'outer' and 'inner' sides of four marinas, two at the Canary Islands and two at southern Portugal, were investigated using three complementary sampling techniques: underwater visual censuses ( UVCs), baited cameras ( BCs), and fish traps ( FTs). We firstly investigated the complementarity of these sampling methods to describe species composition. Then, we investigated differences in taxonomic ( TD), phylogenetic ( PD) and functional diversity ( FD) between sides of the marinas according to each sampling method. Finally, we explored the applicability/reproducibility of each sampling technique to characterize fish assemblages according to these metrics of diversity. UVCs and BCs provided complementary information, in terms of the number and abundances of species, while FTs sampled a particular assemblage. Patterns of TD, PD, and FD between sides of the marinas varied depending on the sampling method. UVC was the most cost-efficient technique, in terms of personnel hours, and it is recommended for local studies. However, for large-scale studies, BCs are recommended, as it covers greater spatio-temporal scales by a lower cost. Our study highlights the need to implement complementary sampling techniques to monitor ecological change, at various dimensions of biodiversity. The results presented here will be useful for optimizing future monitoring programs. [ABSTRACT FROM AUTHOR]

The efficacy of various sampling gears for age-0 Mountain WhitefishProsopium williamsoniis largely unknown, which makes it difficult to investigate recruitment and early life history dynamics for the species. We compared four gears: seine, backpack electrofisher, minnow trap, and lighted minnow trap. Gears were tested in backwaters, large channels, and small channels in the Madison River, Montana. No age-0 Mountain Whitefish were captured in minnow traps or lighted minnow traps. Mean CPUE of age-0 Mountain Whitefish was higher for seining (0.18 fish/m2; SD, 0.39) than for electrofishing (0.01 fish/m2; SD, 0.03), and the CV was lower for seining. A broader length distribution was sampled by seining (17–41 mm) than with electrofishing (21–36 mm). Age-0 Mountain Whitefish CPUE in seines was highest in backwaters. In channel sites, Mountain Whitefish presence was associated with areas of still or slow water ≥2 m2. Relative to the other sampling gears we evaluated, seining was the most efficient gear for sampling age-0 Mountain Whitefish in a lotic ecosystem. Received June 19, 2016; accepted October 20, 2016 Published online January 12, 2017 [ABSTRACT FROM AUTHOR]

Fish traps were soaked for long (d) and short (min) intervals to examine the relationship between the catch of Black Sea BassCentropristis striataand soak time for traps used in the Middle Atlantic Bight commercial fishery. First, we soaked traps over a 14-d period to examine how catch changes over time and modeled catch as a function of soak time using two three-parameter models from the literature. Maximum catches were obtained after 11 soak days before declining. Models applied to catch and soak time data fit reasonably well and may be used to correct for changes in soak time to develop abundance estimates. Second, we used a modified trap equipped with video cameras to observe fish interactions, including entry and escapement dynamics with traps over short (~60 min) soak times. Out of all the fish that were observed entering the trap, 48 (84.2%) exited while 9 (15.8%) were caught. Patterns for cumulative distributions of entries and exits indicated that entry and escapement behaviors may lead to saturation in Black Sea Bass traps used in the Middle Atlantic Bight. Additional study is needed to examine the dynamics of the saturation process and to elucidate how well trap catches reflect true abundance. Received February 2, 2016; accepted September 7, 2016 Published online December 20, 2016 [ABSTRACT FROM AUTHOR]

At depths smaller than those of the daytime bathypelagic layers, the vertically migrating perch Perca fluviatilis fry form a benthic community. Modified Breder traps were used for sampling these deep benthic perch fry during their daylight stay in the benthic habitat of Římov Reservoir, Czech Republic, in spring 2007 and 2009. The size and condition of perch caught in the traps (the catch was removed in late afternoon) was compared to that of fish caught by trawl in the bathypelagic habitat at midday and by electrofishing in the littoral habitat at midday. Perch from the traps were in significantly worse condition compared to those from the trawl and electrofishing. All fish left in the traps overnight were dead. It is likely that the evening migration to the epilimnion is essential for perch fry performing diel vertical migrations in stratified canyon-shaped reservoirs. The sampling efficiency of traps is strongly affected by the abundance of targeted fish and their swimming activity in a cold and dark benthic habitat. [ABSTRACT FROM AUTHOR]

Traps are used by artisanal fishers as fishing gear in places where other fishing modalities are impeded or limited. The advantage of this type of fishing modality is the possibility of keeping fish alive and in the case of capturing species of low commercial value or size below the permitted minimum this fishing gear allows the release of such specimens back to nature, resulting in a sustainability aspect to the use of this fishing gear. This study aims to evaluate the effects of different attractors and times of submersion on the efficiency of the traps used. Sardines, shrimps and trash fish were employed as attractors. To evaluate the soak time, two periods were tested: 24 and 96 hours. The sardines, used as the attractor, resulted in a production of 1,296.4 ± 397.4g, significantly superior (p

Se realizó un estudio orientado a evaluar tres tipos de trampas (eficiencia de captura, estructura de tallas, selectividad y composición de especies) para la captura de peces marinos en el Golfo de California. La recolecta de muestras se efectuó con trampas de 90 cm de ancho, 120 cm de largo y 50 cm de alto, con malla galvanizada cuadrangular en tres tamaños: una trampa completamente construida con abertura de malla de 5 x 5 cm (trampa 1); otra con malla de 5 x 5 cm, pero con el panel trasero de 5 x 10 cm (trampa 2) y la tercera con malla de 5 x 10 cm (trampa 3). Los experimentos se llevaron a cabo entre octubre del 2005 y agosto del 2006. Las especies que presentaron mayor incidencia de captura en cuanto a proporción del volumen total fueron el extranjero (Paralabrax auroguttatus), pierna (Caulolatilus princeps), cabrilla arenera (P. maculatofaciatus) y conejo (C. affinis) y prácticamente todas las capturas tuvieron valor comercial. El número de organismos por trampa por lance decreció al aumentar el tamaño de malla, mientras que la talla media se incrementó con el tamaño de malla de las trampas. Además las tallas son más grandes en cualquiera de las trampas que las obtenidas con piola de mano con anzuelos (el arte de pesca autorizado). Los resultados de la selectividad de tallas indicaron que las trampas de malla grande fueron más selectivas que las de malla más pequeña. En consecuencia, la captura con tram-pas es mejor que con los anzuelos y línea de mano, por lo que las trampas serían una muy útil adición al conjunto de artes de pesca usados en la pesca artesanal de la costa de Sonora, México.Size structure, selectivity and specific composition of the catch in traps for marine fish in the Gulf of California. We analyzed the performance of three traps for marine fish between October 2005 and August 2006 in the Gulf of California, Mexico. The performance was measured as difference in selectivity, fish diversity, size structure and yield. The samples were collected with quadrangular traps 90 cm wide, 120 cm long and 50 cm high. Trap type 1 had a 5 x 5 cm mesh (type 2: 5 x 5 cm including a rear panel of 5 x 10 cm; trap 3: 5 x 10 cm). Most abundant in our traps were: Goldspotted sand bass (Paralabrax auroguttatus), Ocean whitefish (Caulolatilus princeps), Spotted sand bass (P. maculatofaciatus) and Bighead tilefish (C. affinis); there was no bycatch. The number of fish per trap per haul decreased when mesh size was increased. We also observed a direct relationship between mesh size and average fish length. By comparing our traps with the authorized fishing gear (hooks-and-line) we found that the size structure is larger in traps. Traps with larger mesh size were more selective. Consequently, we recommend adding traps to hooks-and-line as authorized fishing gear in the small scale fisheries of the Sonora coast, Mexico. Rev. Biol. Trop. 56 (3): 1403-1417. Epub 2008 September 30.

When sampling wild animals, the collection methods used can impact the number, sex, size, and behaviour of individuals captured and it is important to understand these impacts when making inferences about populations. While biases between different types of sampling gear are well recognized, biases that arise from using different models of the same gear type are often not considered. To test if different models of the same gear type influence the number and type of individuals collected, we first used two different models of the same gear type (silver and black minnow traps) to collect an invasive fish species, the round goby (Neogobius melanostomus). Next, we tested if any observed differences in capture rates between the different trap models could be explained by differences in: (a) colour, by painting silver traps black and deploying them in the field; and/or (b) retention, by quantifying fish exit rates from the different trap models in the laboratory. We found that silver traps captured approximately twice as many fish as black traps, and that the fish captured in silver traps were smaller on average. Next, we found when silver traps were painted black these now black traps still had catch rates comparable to regular silver traps. Lastly, we found that fish were 13 times more likely to exit from black traps compared to silver traps. Our results suggest that different models of the same gear type can differ substantially in terms of the number and type of individuals they capture. Being aware of these slight dimensional differences between models within a gear type and understanding how even small shape differences can impact the samples collected is important when assessing populations of wild animals and when comparing results and data across studies. To explore this issue further, we conducted a literature survey and identified that of the 275 studies identified that employed minnow traps, 37% provided no description of the traps employed. We advocate that researchers provide detailed information related to the sampling gear used when collecting wild animals to inform appropriate inferences and improve comparative analyses across studies. [ABSTRACT FROM AUTHOR]

Fishways can restore functional connectivity within rivers for migratory fish where barriers compromise connectivity. Providing fish passage is particularly important for semelparous, anadromous species that require access to upriver habitats to successfully reproduce. From 2017 to 2020, we used a combination of acoustic and radio telemetry to investigate the passage success of Chinook salmon (Oncorhynchus tshawytscha) in the upper Yukon River through the wooden Whitehorse Rapids Fishway and compared this to the migration of salmon in the nearby free-flowing Takhini River. The upper Yukon River population of Chinook salmon studied here is highly unique, completing a 2800 km inland migration to Whitehorse, YT, before attempting to pass the Whitehorse Hydro Plant (WHP) to reach spawning sites upstream. We found that upstream passage success was variable across four years of study (0%–66%), was low overall at 31%, and was considerably lower for female salmon. In contrast, salmon migrating up the free-flowing Takhini River had high migration success to spawning grounds and had many times faster migration rates. Attraction (86%), entrance (77%), and passage efficiency (36%) were less than that reported for Chinook salmon at other fishways. Within the fishway, a disproportionately high number of salmon returned downstream upon reaching a daytime-operated viewing chamber (fish trap) located ∼115 m up the fishway. Upon passing the fishway, salmon had high migration success to spawning grounds, though 12% of salmon returned downstream of the WHP, typically after multiple days and after traveling dozens of kilometres upstream of the facility. Findings from this study reveal opportunities to improve fishway performance and thus connectivity for one of the world's most impressive animal migrations. [ABSTRACT FROM AUTHOR]

Commercial fish traps were recently implemented at a limited scale in the lower Columbia River in efforts to selectively harvest hatchery-origin fishes with minimal mortality of wild-origin salmonids listed under the U.S. Endangered Species Act. Prior studies of a modified passive trapping technique demonstrated nearly 100 % survival among adult salmonids released as bycatch. Building upon this research, additional survival studies for adult coho salmon, spring-run Chinook salmon, and summer-run Chinook salmon were conducted between 2019 and 2021 at two separate fish trap sites in the lower Columbia River. Over three years of study, we used mark-recapture and net pen holding methodologies to estimate post-release survival of Chinook salmon and coho salmon, respectively. Evaluating detections of Chinook salmon tagged and released from a passively operated fish trap in 2019, detection at Bonneville Dam over a mean 6.5 d upriver migration (167 km) was 1.000 (95 % CI: S ≥ 0.970) for the sample genetically assigned to populations originating upriver of Bonneville Dam. Through two separate net pen holding studies, post-release survival of coho salmon was estimated at 1.000 (95 % CI: S ≥ 0.975) over 4 d in 2020 and 0.965 (95 % CI: 0.948 ≤ S ≤ 0.969) over 6 d in 2021. Given that these analyses lacked control groups to adjust survival estimates for confounding mortality effects, study results are inherently conservative. Ultimately, the findings of our research support the conclusions of prior studies and further suggest that passively operated fish traps may allow for selective harvesting of targeted fish stocks with little to no mortality of adult salmonid bycatch. • Modifications to salmon trap operations have improved bycatch survival. • Release survival of adult salmonids from passively operated fish traps neared 100 %. • Survival results validated the findings of prior studies for salmon traps. • Salmon traps allow for selective harvesting and bycatch mortality reduction. [ABSTRACT FROM AUTHOR]

Research on the stock status and exploitation of the blue swimming crab Portunus pelagicus (Linnaeus 1758) in Lasongko Bay was conducted from April 2013 to March 2014. Blue swimming crabs were sampled monthly using gillnets and traps. Data on the number of fishermen and crab fishing gear were obtained via census and from secondary data and were analysed descriptively for every sampling period. Total catches of crabs were analysed using one-way ANOVA and t-test at p= 0.05. The status of crab stock was analysed using a Beverton--Holt model. The results showed that the number of fishing gear increased rapidly from 2006 to 2014, but was not proportional to the increases in crab catches, while the number of fishermen declined. The number of fishing gear and catch in 2006 and 2014 were 2,670 and 15,355 units and 44,194.56 kg and 66,926.6 kg, respectively. Daily crab catch were significantly different between the months. Crab stocks have been overfished and are currently considered critical, and thus the implementation of effective management is necessary. [ABSTRACT FROM AUTHOR]

Hatch time of American lobster ( Homarus americanus) varies between years and regions, which affects temperature experienced by the developing larvae and hence the time and distance these drift before settling. Hatch time can be assessed by working with fishermen and inspecting the brood of gravid females caught in their traps. However, this would require frequent sampling as the hatch period is protracted (≈7-12 weeks) and would require dedicated sampling in many regions where hatching occurs outside of the fishing season. To address these limitations, we tested the accuracy with which hatch time can be predicted by taking egg samples during the fishing season and estimating embryo development using embryonic eye size (Perkins eye index) and lab-derived, temperature-dependent development functions. Using a linear development function and observed variability in Perkins eye index at hatch, we successfully predicted 100% of the observed 50-day hatch period, and 96% of predicted hatch dates fell within this period. Our results suggest that samples can be obtained in collaboration with fishermen to predict the timing and progression of hatch of American lobster. [ABSTRACT FROM AUTHOR]

Fishing traps are perhaps one of the least studied categories of archaeological remains in Sweden. Since at least the Mesolithic (10 000-5 000 BP), use of systematic fishing structures to harvest the sea of its resources is evidenced in the archaeological record. Such structures are often found in lakes, rivers and estuaries. Relatively often, Bohusläns Museum has, during underwater archaeological surveys, discovered previously unrecorded fishing traps that often fall within the time frame of Middle Ages (11th to 16th centuries) to the modern day (19th to 20th centuries). Such structures, therefore, are not just a peculiarity but more a regularity - in that they have had a widespread use in Swedish culture and livelihood. One such example of this is from Lake Gärdsken, Alingsås. Alingsås is mentioned in the written record from at least the 1300s although it not implausible to assume that the area had been settled previous to this. In Sweden, fishing has not only constituted a pastime or a profession, but has served as a complement to the household. Farmers for example, would often fish to support their meagre income or diet. Although fishing traps have a widespread use, form and geography, all have the same function - to catch fish. This article includes the case study of Lake Gärdsken, Alingsås. Bohusläns Museum (the provincial museum of the county of Bohuslän) has undertaken several archaeological investigations in the lake since 2009. [ABSTRACT FROM AUTHOR]

Cod pots are considered seal-safe fishing gear and are proposed as a solution to mitigate the ongoing seal-fisheries conflict in the Baltic Sea. This study examined various factors which could affect the entry and exit behaviour of cod in relation to cod pots. Statistical modelling was used to determine which of these factors most affected the pots' catch per unit effort (CPUE). Two fishing trials were conducted off the coast of Bornholm, Denmark, using six pot types with different design features, equipped with underwater camera systems to record the behaviour of the cod in relation to the pots. Four pot types were floating pots with one entrance and two were bottom standing with three entrances. Different pot types showed significantly different CPUEs and the pot type was an explanatory factor for entry and exit rates for both trials. In trial 1 artificial light was used for filming and results showed an increase in entry rates during the night time, suggesting that lights attract fish to the pot when the dark surroundings make the effect of the light more noticeable. Exit rates in trial 1 increased with an increasing number of fish in the pot while they decreased with soak time. In trial 2, when no artificial light was used, a saturation effect was found in that the probability of cod entering the pot lessened as the number of cod already in the pot increased. However, the exit rates in trial 2 also decreased with increasing number of fish in the pot. The study offers greater depth to the understanding of CPUE results by examining fish behaviour around the pots and not just the raw catch data. This in turn contributes to the ongoing search for the most favourable pot designs. [ABSTRACT FROM AUTHOR]

An interview with Philip Walsh, fisheries technologist with the Centre for Sustainable Aquatic Resources, Fisheries and Marine Institute at the Memorial University in Canada, is presented, about their work on baited pots.

In order to allow cod pots to be an alternative to gillnet fisheries, catch has to be increased. In this study we evaluate pot entrance modifications as a means to increase pot catch efficiency. We connect entrance modifications to in-situ cod behavioural events in relation to pot entrances. Pots with entrances lacking funnels allow for a higher proportion of entering cod but also to a larger extent allow cod to exit pots. We show how pots equipped with funnel entrances generate increased catch by preventing escape and, through that, serve as an important factor in regulating cod pot catches. Importantly, we show how entrances equipped with funnels, although inducing a higher proportion of turn behaviour along with increased time in entering, result in a higher net effect in catch than the positive effect in entry if not using funnels. With target species behaviour being a strong regulator of gear catch efficiency, we stress the importance of in-situ observations of specific behavioural components in the fishing gear development process. [ABSTRACT FROM AUTHOR]

The article discusses the use of baited traps in the Newfoundland and Labrador fishery for snow crab and the "Sustainable Fisheries Framework" published by the Fisheries and Oceans Canada.

Lake Condah (Tae Rak) in south-western Victoria, Australia, is one of the world's most ancient examples of traditional aquaculture, consisting of complex systems of traps and ponds used by Gunditjmara (Indigenous people) over millennia to collect short-finned eel ( Anguilla australis) for consumption and trade. Artificial draining of the lake during the nineteenth century reduced surface water retention in the landscape and rendered most of the eel traps inoperable. In this paper, we describe the traditional eel fishery at Lake Condah and its historical and cultural significance to the Gunditjmara people. We document the impacts of European settlement on the traditional eel fishery, and describe the processes and events leading to eventual restoration of the lake and subsequent reactivation of major parts of the traditional aquaculture system. In addition to restoring an important ecological asset to the region, the restoration project provided significant benefits to the Gunditjmara people, including enhanced connection to country and culture, opportunities for economic development and employment, and increased capacity for traditional owners to progress and negotiate outcomes within regulatory and administrative frameworks. Aspects identified as critical to the ultimate success of the Lake Condah restoration project include: open and transparent lines of communication with stakeholders; building of trust and confidence with key individuals over sustained periods; use of strategic and business planning documents to guide activities; commissioning of high quality technical information to support and justify activities; representative leadership structures, and effective use of 'two-way learning' across western scientific and indigenous knowledge systems. [ABSTRACT FROM AUTHOR]

We investigated food preferences of Atlantic Hagfish ( Myxine glutinosa) in Bigelow Bight in the Gulf of Maine by deploying traps at three moderate depths (ranging from 61 m to 132 m) using different types of bait (fish, crabs, and clams) singly and in mixtures. We counted the numbers of specimens caught in each trap, recorded their individual weights and lengths, and noted the presence of eggs. Bait containing fish consistently attracted the greatest number of hagfish, while invertebrate-based baits were less effective: there was a nine-fold increase in catch rate for traps containing fish bait compared to traps containing only clam bait, and no hagfish were caught using only crab bait. Atlantic Hagfish appear to be adept at detecting even small quantities of fish because baits consisting of 10% fish and 100% fish were equally effective. Even at the relatively shallow and closely adjacent depths sampled we found longer and heavier hagfish at the deepest sampling sites, and individuals from those sites had larger eggs than those from shallower depths. [ABSTRACT FROM AUTHOR]

Cabrera National Park is a Marine Protected Area (MPA) located in the South of Mallorca, Balearic Islands, Spain. It has a valuable ground fishery that includes several species of crustaceans of commercial interest, such as the European spiny lobster Palinurus elephas . Lobster traps, although permitted and even promoted by the park's authorities, have been abandoned due to the higher efficiency and catch per unit effort of the trammel nets. This study evaluates traditional and modern lobster trap designs to determine the most suitable one as an alternative to trammel nets. The gear was first tested in an aquarium and consisted of a reed trap, a plastic trap and a metal trap, all three historically used in Mallorca, and a modern Japanese collapsible trap. By conducting behavioral observations and exposing 40 lobsters to the traps it was found that the collapsible trap captured 20% of the lobster exposed to the trap, while the plastic trap only 10% and the reed and metal trap only 2.5% and 0%, respectively. In addition, experimental trials were conducted in a fishing ground of Cabrera National Park using two 450 m long strings of traps. Each string was composed of 30 collapsible traps or 30 plastic traps, with traps spaced at 15 m intervals along the line. Lobster catches were 24 (0.8 lobster/450 m) in the plastic traps, but only 9 (0.3 lobster/450 m) in the collapsible ones. When considering that the minimum legal size for lobsters is larger than 9 cm carapace length (CL), only 9 lobster (0.3 lobster/450 m) could be landed after deploying 1800 traps, and all of them coming from plastic ones. To compare the effectiveness of traps with lobster trammel nets, 14 fishing operations were carried out with a total of 5950 m of net deployed. Thirty-three lobsters were captured (2.37 lobster/450 m) in the nets, of which only 17 reached commercial size (1.22 lobster/450 m). Although the collapsible trap has caught more lobsters in the aquarium compared to the plastic trap, the plastic trap performed better in the field. This appears to be due to the effects of bycatch species, particularly octopus. Our results stressed the necessity of implementing an evaluation of the lobster population dynamics to design more efficient management measures. The fishers themselves recognize the need to an agreement for changing the paradigm from maximizing catches to maximizing profit. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]