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Trap‐and‐transport of migratory fish is commonly used to bypass in‐river obstructions. On the River Conon in Scotland, Atlantic salmon (Salmo salar) smolts are transported around two hydropower facilities. Smolt release occurs during daylight, when predation rates can be high. A novel automatic release cage (ARC) was designed to release smolts at night. Smolts were fitted with acoustic tags (n = 99) to compare survival. High post‐release mortality was identified in the day‐release group, with night‐release survival >40% higher. ARCs can provide fishery managers with a cost‐effective and reliable method of improving smolt survival. [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]

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]

Invasive sea lampreys ( Petromyzon marinus) in the Laurentian Great Lakes are the target of binational control. Trapping of adults could be used for control if trap success was higher. At a hydro-generating station on the St. Marys River, we tested whether the probability of trap entry is low (0.2-0.3) because ( i) lampreys spend insufficient time near traps to find and enter the trap, ( ii) high discharge at trap sites makes attractant flow from traps difficult to detect or trap openings difficult to reach, and ( iii) conspecifics impede trap entry. Discharge at the site was manipulated nightly, and the behaviour of lampreys at trap openings was video-recorded. Odds of a lamprey reaching a trap opening and entering the trap were 3.4 and 1.6 times higher, respectively, with every second spent at a trap. The probability of reaching a trap was not lower on nights when discharge was high or when conspecifics were present at the trap opening. Improved trap entry will require manipulation of stimuli other than discharge that affect the time spent at traps. [ABSTRACT FROM AUTHOR]

Fish traps are one of the most widespread and enduring features of the maritime landscape. Recent research in Ireland has identified a great number of traps, most of which date from the early to late medieval periods. This paper presents the findings of a recent survey of Lough Swilly in north-western Ireland where a series of fish traps offers new insights into the survival, diversity and role of these sites in the post-medieval period. [ABSTRACT FROM AUTHOR]

The catches of the traditional fish traps in the Kosi Bay estuarine lakes were monitored over a 30-year period from 1981 to 2010. Monitoring data were used to provide estimates of, and insights into, catch size and species composition as well as seasonal and annual cycles of catch abundance. Over 1.2 million fish, comprising 43 species and 23 families, were estimated to have been caught during the study period. Tag-and-release data were used to estimate the impact of trap fishing on fish stocks and comparisons were made with recreational fishing to indicate overall fishing pressure and the sustainability of the fishing. Trap numbers remained fairly similar from the first year of monitoring (1981) until 1994, but thereafter they more than trebled by 2001; although numbers decreased after this, they remained well above earlier levels. During this period, recreational angling was an important factor, and gillnetting — both legal and illegal — added to the fishing pressure. Information from the fish trap monitoring, together with results from fish mark and recapture studies, suggest a very high, and possibly unsustainable, catch rate that requires management intervention to return them back to historical and sustainable levels. [ABSTRACT FROM AUTHOR]

The effects of the putative hormonal pheromones 17α, 20β-dihydroxy-4-pregnene-3-one (17,20β-P), 17,20β-P-20-glucosiduronate, and prostaglandin F-2α (PGF-2α) injected into female channel catfish, Ictalurus punctatus, were investigated to determine whether male channel catfish and blue catfish, Ictalurus furcatus, could be attracted to the injected females. Females were distributed into traps placed in ponds containing either male channel catfish or blue catfish. Traps were checked six times in a 96-h period. Males were 17.9 times more likely to be captured with a PGF-2α-injected female than with an ethanol-only injected female, or a 17,20β-P-injected female, and 3.5 times more likely to be captured with a PGF-2α-injected female than with a 17,20β-P-glucosiduronate-injected female. Males were 6.0 times more likely to be caught between 48 and 96 h post-injection than between 12 and 24 h post-injection. These results suggest that the overall best pheromone to attract blue catfish and channel catfish males is PGF-2α at 48-96 h post-injection. [ABSTRACT FROM AUTHOR]

Fisheries scientists and managers are increasingly engaging with fishers’ knowledge (FK) to provide novel information and improve the legitimacy of fisheries governance. Disputes between the perceptions of fishers and scientists can generate conflicts for governance, but can also be a source of new perspectives or understandings. This paper compares artisanal trap fishers’ reported current catch rates with landings data and underwater visual census (UVC). Fishers’ reports of contemporary ‘normal’ catch per day tended to be higher than recent median landings records. However, fishers’ reports of ‘normal’ catch per trap were not significantly different from the median CPUE calculated from landings data, and reports of ‘good’ and ‘poor’ catch rates were indicative of variability observed in landings data. FK, landings and UVC data all gave different perspectives of trends over a ten-year period. Fishers’ perceptions indicated greater declines than statistical models fitted to landings data, while UVC evidence for trends varied between sites and according to the fish assemblage considered. Divergence in trend perceptions may have resulted from differences in the spatial, temporal or taxonomic focus of each dataset. Fishers may have experienced and understood behavioural changes and increased fishing power, which may have obscured declines from landings data. Various psychological factors affect memory and recall, and may have affected these memory-based estimates of trends, while different assumptions underlying the analysis of both interview data and conventional scientific data could also have led to qualitatively different trend perceptions. Differing perspectives from these three data sources illustrate both the potential for ‘cognitive conflicts’ between stakeholders who do not rely on the same data sources, as well as the importance of multiple information sources to understand dynamics of fisheries. Collaborative investigation of such divergence may facilitate learning and improve fisheries governance. [ABSTRACT FROM PUBLISHER]

Abstract: Most population estimates of American lobster (Homarus americanus) rely on catch data from the commercial fishery. Therefore, it is important to understand the factors that affect the catchability of lobsters and their behavioural response to traps. Commercial fishermen claim that if lobster traps are fished in linked sets, or trawls, that the trap that is adjacent to the surface buoy generally has a lower catch, presumably because of increased trap movement due to more direct exposure to wind influence. For four consecutive weeks during May and June 2007, we recorded the catch of 944 trap hauls to determine if there are differences in lobster catch rates among the four linked traps on a line, and if these differences are related to wind speed. In addition, on the second and fourth week of the study, every second trawl received a gear modification designed to decrease the effect of the wind on catch rates. The study found that there were no significant differences in catch rate among the four traps in a trawl. Although wind and catch rate were expected to be somehow related, no meaningful linear relationship between these variables was found. These results indicate that common assumptions about the effects of gear design on lobster catch rate may not be supported when examined systematically, and that relationships between wind, temperature and catch rate are not always evident. [Copyright &y& Elsevier]

This paper examines the use of V-style fish traps on the western recessional shorelines of ancient Lake Cahuilla. We use multiple lines of evidence to examine the function of these traps, including ethnographic data, fish biology, excavations of fish traps, and experimental replication of fish trap designs. Our study indicates that biological characteristics of the fish were central to the effectiveness of the traps and dictated trap placement and design. [ABSTRACT FROM AUTHOR]

Derelict (abandoned or lost) traps targeting blue crab Callinectes sapidus have the potential to affect the blue crab fishery and other marine-oriented species. We used side-scan sonar to locate derelict traps and assess their extent and accumulation rate. Experimental traps were monitored at four locations to calculate catch rates of marine organisms and trap degradation rates. In 2006, 635-676 derelict traps were identified in a 33.5-km² area of the lower York River in Virginia's portion of the Chesapeake Bay. Trap loss rates are estimated at 30%, resulting in the potential addition of over 100,000 traps annually to the Chesapeake Bay derelict trap population in Virginia. The top four species captured in the experimental traps were blue crab, Atlantic croaker Micropogonias undulates, oyster toadfish Opsanus tau, and white perch Morone americana. Experimental derelict traps captured 50.6 blue crabs·trap-1. season-1 during April-November 2006 and 13.6 Atlantic croakers·trap-1·season-1 during May-August 2006. There was no difference in catch rates between traps of different ages. Baiting traps to simulate entrapped fish (self-baiting) doubled the catch rate. Experimental derelict traps continued to capture organisms for at least 1 year, which suggests that derelict traps could affect blue crab populations. [ABSTRACT FROM AUTHOR]

The article discusses a study on ghost fishing of lost octopus and fish traps in the northeastern Atlantic Ocean. It mentions that slates, video and still photography cameras were used by scuba divers to monitor the octopus traps that were located in shallow waters. It presents a comparison of the variety of species caught by the octopus traps and fish traps. It attributes the loss of traps to bad weather and interaction with commercial gear.

The present study aimed to determine the relative catch efficiencies of two different fish traps in Ýskenderun Bay. Trap model A had an entrance supported by a hoop, whilst the entrance of model B was unsupported. Fieldwork was carried out in Pirinçlik-Madenli Bight (Ýskenderun Bay) between 15 July and 15 November 2001. Forty basket traps were set each day during the 124-day study period. Overall 1242 individuals, 16 species and 11 families of fish and commercial invertebrates were recorded. The total biomass was 317.73 kg. Fishing effort, irrespective of trap models was 0.25% and the highest catch weight was in August, September and October. The amount of by-catch (0.04 kg) and discards (0.07 kg) were quite low. [ABSTRACT FROM AUTHOR]

Arctic charr, Salvelinus alpinus, tend to form stunted populations presumably due to competition for limited resources. In this context a long-term intensive fishery programme aiming at reducing charr density, and thereby increasing growth and harvestable sizes, was initiated in the early 1980s in a Norwegian alpine lake. Here we present long-term data on catch statistics and changes in mean weights of charr caught with gill nets on spawning grounds, as well as changes in mean weight of juvenile charr caught with funnel traps during the 1990s. Furthermore, we present results from shorter-term studies on growth, size- and age-distribution, and size-related habitat and resource utilisation of Arctic charr and brown trout, Salmo trutta, in this lake. Mean weight (± SD) of charr caught on the spawning grounds increased significantly from 129.8 g (±11.9) in the years 1982–1990 to 213.1 g (±37.8) in the years 1996–1999, whereas catch per unit of effort decreased significantly. Mean weight of juveniles caught in funnel traps increased significantly from 21.2 g (±6.9) in 1993 to 41.9 g (±14.8) in 1999. Apparently the increase in weight of spawning charr coincided with the onset of trap fishing for juvenile charr. Compared to generally shallow dwelling trout, charr grew rapidly and were generally found in deeper areas of the lake. Charr went through a distinct size-related niche shift from mainly consuming small zooplankton in the pelagic to consuming large benthic prey in shallower waters. Resource and habitat utilisation in different size-groups of charr and trout are discussed with respect to possible competitive and predatory intra- and interspecific interactions, and with regard to management of charr populations. [ABSTRACT FROM AUTHOR]

We examined the effects of fishing with crustacean traps on benthic species in Great Britain by means of qualitative and quantitative experiments. Experimental sites were selected where fishing using pots or creels was practised regularly and where species perceived to be potentially sensitive to damage were present. The effect of Nephrops creels on different sea pen species was studied in Scottish sea lochs. Sea pens were observed to bend in response to the pressure wave before the creel made contact. After smothering and even uprooting, they re-established themselves when in contact with muddy substrate. Observations of lobster and crab pots being hauled from rocky substrates in southern England, revealed that the habitats and their communities appeared relatively unaffected by potting. The slow-growing, long-lived, pink sea fan Eunicella verrucosa were observed to flex under the weight of pots as they passed and then returned back to an upright position. Quantitative studies, undertaken in south England and west Wales, were based on surveys carried out along transect lines before and after a month of pot fishing for crabs and lobsters. The results suggest that four weeks of fairly intense fishing did not have immediate detrimental effects on the abundance of the species selected for study, although some individual ross coral colonies (Pentapora foliacea) were damaged. [ABSTRACT FROM PUBLISHER]

This paper proposes a production function for a trap fishery and develops its implications for the economic management of associated inputs. The field observations and anecdotes from fishermen are drawn from the American lobster fishery, but the approach may also be used for other trap fisheries. The development includes a spatial aspect of fixed gear fisheries and an intuitive rationale for a congestion externality in such fisheries. This effect does not involve population dynamics per se. However, the production function developed below could eventually be imbedded within a population dynamics model, although this is not done here. This eventual imbedding is necessary not only because of the biological issues explained by population dynamics but also because of the dependence of price on the age-class structure of the population. A principal finding is that there are plausible reasons to expect market failure associated with a trap congestion externality and a soak time too short for cost effectiveness. The numerical analysis is consistent with the theory, and if this finding is supported by further research, then operating costs could be reduced with no change in catch by using more traps and longer soak times. [ABSTRACT FROM PUBLISHER]

A combination of visual census and trap sampling in St. John, USVI indicated that traps performed better in gorgonian habitat than in adjacent coral reef habitat. Although most families were seen more commonly in coral habitat, they were caught more often in gorgonian areas. Traps probably fished more effectively in gorgonian habitats, especially for migrating species, because traps provided shelter in the relatively topographically uniform environment of gorgonian dominated habitats. Recently, trap fishermen on St. John have been moving effort away from traditionally fished nearshore coral reefs and into a variety of more homogeneous habitats such as gorgonian habitat. Consequently, exploitation rates of the already over-harvested reef fish resources may be increasing. Reef fish managers and marine reserve designers should consider limiting trap fishing in gorgonian habitats to slow the decline of reef fisheries. [ABSTRACT FROM AUTHOR]