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Concern about bycatch of marine mammals by fishery research gear has led to the use of mammal excluder devices (MEDs) in some surveys. We measured the effect of a rigid-grate MED on trawl fishing effectiveness for juvenile Pacific salmon Oncorhynchus spp. and other upper-pelagic species in the northern California Current. Catches of 11 taxa were compared among sets of a pelagic rope trawl without an MED and with an MED in two orientations: angled upward or angled downward. We estimated differences in overall catch ratios and size selectivity for each MED orientation compared to the unmodified net. The MED orientation had a species-specific influence on both catch ratio and size selectivity, with median ratios ranging from 0.0 to 1.8 for the upward orientation and from 0.4 to 2.7 for the downward orientation. Video observations helped to explain performance differences and may help to improve MED design. Use of an MED in trawl surveys may substantially increase or decrease the catch of various taxa, contributing further uncertainty to the analysis of survey time series for either abundance or catch composition. [ABSTRACT FROM AUTHOR]

Diamondback terrapins ( Malaclemys terrapin) have experienced declines throughout their range, and accidental mortality in crab pots is a significant conservation concern. To minimize the risk of terrapins entering crab pots, researchers have suggested the use of bycatch reduction devices (BRDs) to reduce the size of crab pot openings and thereby exclude terrapins from entering crab pots. Despite these recommendations, few studies have observed terrapin interactions with BRDs and effectively evaluated the efficacy of these devices at preventing the entry of terrapins into pots., The objective of this study was to determine the effect of BRD presence and orientation on terrapin behaviour around crab pots and overall terrapin capture rates., In a controlled laboratory setting, terrapins investigated crab pots more frequently when crab pots were baited with fish versus chicken. Terrapins were captured more frequently when BRDs were not installed. The presence of the BRDs also increased the length of time necessary for a terrapin to enter a crab pot and decreased the proportion of entries relative to the number of investigations. Vertically-oriented BRDs were more effective than horizontally-oriented BRDs at reducing terrapin captures., To prevent the continued decline of terrapin populations due to crab fisheries, it is recommended that crabbers avoid the use of fish as bait in crab pots to reduce the attractiveness of pots to terrapins and fit all crab pots with vertically-oriented BRDs to reduce terrapin entrapment., Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article offers information on use of insects by-catch in expansion of knowledge in field of entomology. Topics discussed include important consequences of by-catch for non-target insect populations which may interfere with ecosystem services like pollination and natural pest control, data on discarded insect by-catch in a year, detection of new non-target species by examining insect by-catch, and value added collections through insect by-catch.

Various plastic strips and sheets (termed ‘simple anterior fish excluders’−SAFEs) were positioned across the openings of penaeid trawls in attempts at reducing the unwanted bycatches of small teleosts. Initially, three SAFEs (a single wire without, and with small and large plastic panels) were compared against a control (no SAFE) on paired beam trawls. All SAFEs maintained targeted Metapenaeus macleayi catches, while the largest plastic SAFE significantly reduced total bycatch by 51% and the numbers of Pomatomus saltatrix, Mugil cephalus and Herklotsichthys castelnaui by up to 58%. A redesigned SAFE (‘continuous plastic’) was subsequently tested (against a control) on paired otter trawls, significantly reducing total bycatch by 28% and P. saltatrix and H. castelnaui by up to 42%. The continuous-plastic SAFE also significantly reduced M. macleayi catches by ~7%, but this was explained by ~5% less wing-end spread, and could be simply negated through otter-board refinement. Further work is required to refine the tested SAFEs, and to quantify species-specific escape mechanisms. Nevertheless, the SAFE concept might represent an effective approach for improving penaeid-trawl selectivity. [ABSTRACT FROM AUTHOR]

New Zealand sea lions are incidentally killed in the Auckland Islands squid trawl fishery. Sea lion exclusion devices (SLEDs) that allow animals to escape from the trawl net have received considerable development and assessment attention. Nonetheless, there are claims that some animals could suffer head trauma when colliding with the hard grid that forms part of the SLED and this may compromise post-escape survival. We reviewed published and unpublished research that assessed the effectiveness of SLEDs in reducing the incidental capture (i.e. bycatch) of sea lions, including assessments on the likelihood of post-SLED survival. The available evidence shows that SLEDs are effective in reducing sea lion bycatch in trawl nets and contribute to reduced rates of observed sea lion mortality in the Auckland Islands squid fishery. Efforts to test SLED efficacy have shown that most sea lions are likely to survive following their escape via a SLED, despite the shortage of verifying video evidence due to poor visibility at fishing depths. Laboratory necropsies of incidentally caught sea lions have been unable to reliably evaluate post-SLED survivability of sea lions due to the effects of on-board handling of carcasses, including the logistical necessity of freezing them. Some lesions initially considered to be evidence of trauma were subsequently deemed to be artefacts of freezing. Nonetheless, there was no clear difference in the trauma assessments between sea lions caught in nets with and without SLEDs. Biomechanical modelling suggested it was unlikely that impact with a SLED would cause fatal brain trauma and the probability of concussion that could result in post-SLED drowning was probably less than 10%. As fisheries bycatch has been reduced to levels that are unlikely to be driving continued decline of New Zealand sea lions at the Auckland Islands, future work may be better focussed on alternative research and management areas that may be more effective in addressing and reversing New Zealand sea lion population decline. [ABSTRACT FROM AUTHOR]

Bycatch can harm marine ecosystems, reduce biodiversity, lead to injury or mortality of protected species, and have severe economic implications for fisheries. On 12 January 2007, President George W. Bush signed the Magnuson-Stevens Fishery Conservation and Management Reauthorization Act of 2006 (MSRA). The MSRA required the U.S. Secretary of Commerce (Secretary) to establish a Bycatch Reduction Engineering Program (BREP) to develop technological devices and other conservation engineering changes designed to minimize bycatch, seabird interactions, bycatch mortality, and post-release mortality in Federally managed fisheries. The MSRA also required the Secretary to identify nations whose vessels are engaged in the bycatch of protected living marine resources (PLMR's) under specified circumstances and to certify that these nations have 1) adopted regulatory programs for PLMR 's that are comparable to U.S. programs, taking into account different conditions, and 2) established management plans for PLMR's that assist in the collection of data to support assessments and conservation of these resources. If a nation fails to take sufficient corrective action and does not receive a positive certification, fishing products from that country may be subject to import prohibitions into the United States. The BREP has made significant progress to develop technological devices and other conservation engineering designed to minimize bycatch, including improvements to bycatch reduction devices and turtle excluder devices in Atlantic and Gulf of Mexico trawl fisheries, gillnets in Northeast fisheries, and trawls in Alaska and Pacific Northwest fisheries. In addition, the international provisions of the MSRA have provided an innovative tool through which the United States can address bycatch by foreign nations. However, the inability of the National Marine Fisheries Service to identify nations whose vessels are engaged in the bycatch of PLMR's to date will require the development of additional approaches to meet this mandate. [ABSTRACT FROM AUTHOR]

Recently, the increasing population of giant jellyfish Nemopilema nomurai has negatively affected coastal fisheries in Korea. As a result, the fishing industry has begun developing devices to prevent jellyfish capture. In this study, we assessed the performance of a conical jellyfish exclusion device in the coastal areas of Yokji Island in southern Korea during 2009. After hauling, we measured the length, diameter, and weight of the jellyfish and fish that were captured by the cod end and cover net. We found that the captured species included N. nomurai, silver croakers Pennahia argentata, yellow croakers Larimichthys polyactics, shotted halibut Eopsetta grigorjewi, largehead hairtails Trichiurus lepturus, and melon seeds Psenopsis anomala. The catch ratios of the giant jellyfish that entered the cod end in terms of weight ranged from 0.005 to 0.027. In contrast, the catch ratios of total fish in terms of weight and number were 0.793 and 0.835, respectively. On selectivity analysis of a conical separator for individual fish species, their exclusion ratios were independent of their length, and were similar to their observed exclusion ratios in terms of number. These results indicated that the conical jellyfish exclusion device performs well; however, some improvements are needed to minimize the escape of fish from the net. [ABSTRACT FROM AUTHOR]

By-catch is a serious conservation threat to populations of numerous marine species, including the diamondback terrapin. Terrapins are top level predators in their estuarine environments and can play an important role in maintaining salt marsh integrity. Unfortunately, numerous populations have declined due to drowning in submerged commercial and recreational crab pots. By-catch reduction devices (BRDs) were developed to prevent terrapin by-catch without affecting crab capture, and they have been shown in previous studies to be effective. The current study examined the efficacy of BRDs in reducing terrapin by-catch in a depleted population of terrapins along the Gulf Coast of Alabama. The BRDs significantly decreased terrapin by-catch (an approximate 90% reduction). There was no significant reduction in the overall capture of crabs in BRD-equipped pots; however, capture of marketable-sized crabs was significantly lower in pots modified with BRDs. This latter finding was in contrast to several large scale studies that had much larger sample sizes and found no significant reduction in the capture of marketable-sized crabs with the use of BRDs. The results indicate that BRDs represent an effective and practical management tool in reducing terrapin by-catch in commercial and recreational crab pots in Alabama. [ABSTRACT FROM AUTHOR]

Quantifying sessile marine invertebrate recruitment often requires destructive sampling or extrapolation from artificial substrata, the latter introducing the danger of artifacts. We measured intertidal mussel recruitment into mussel beds and into brushes at three-month intervals for five years across 3,200 km of southern Africa and determined substrata effects on recruitment rate. Recruitment into mussel beds showed a strong, coast-wide gradient, with high recruitment on the West coast, diminishing on the South coast, and increasing slightly on the East coast. At scales of 10 s of km, brushes reflected natural temporal recruitment variability, with a strong significant linear correlation between recruitment into brushes and into mussel beds. However, the relationship became semi-logarithmic when comparing among locations at a scale of 100 s of km. Artificial substrata thus reflect local natural settlement well but may be a poor indicator of it when spatial scales are large, particularly when mussel bed topography is complex, or localities have very different recruitment densities. [ABSTRACT FROM AUTHOR]

The article presents a study on a bycatch reduction device (BRD) that can be used as a tool to conserve diamondback terrapin without affecting the catch of blue crab. The study conducted in Chesapeake Bay involves testing a mechanism for reducing bycatch of diamondback terrapin Malaclemys terrapin in blue-crab straps without impacting the blue crab catch. Terrapin captures at two shallow-water sites are compared using 10 paired sets of a trap fitted with BRD and a trap without BRD. The number, size, and condition of the captured crabs are recorded. The findings of the study show that crab catch was equivalent between traps with and without BRDs, however, traps with BRDs are effective in excluding all but the smallest terrapins from entering crab traps and had no effect on crab catch.

This paper explores the evolution of a trading zone by organizing the case study of turtle excluder devices within the model proposed by . The case study offers evidence that trading zones do evolve and that the concepts of enforced and fractionated trading zones hold practical utility for describing and defining the complexities of actual exchanges. In this case a trading zone evolved from enforced to fractionated and ultimately diverged into two trading zones. For each step of the evolution I describe the forces that drove these transitions. Finally, I present an adapted trading zone model that is conceptually a better fit for the turtle excluder device case study. [Copyright &y& Elsevier]

Plasticised membranes using 2-[{(2-hydroxyphenyl)imino}methyl]-phenol (L1) and 2-[{(3-hydroxyphenyl)imino}methyl]-phenol (L2), have been prepared and investigated as Cu2+ ion-selective sensors. Effect of various plasticisers, namely, dibutyl phthalate (DBP), dibutyl sebacate (DBS), benzyl acetate (BA), o-nitrophenyloctylether (o-NPOE) and anion excluders, oleic acid (OA) and sodium tetraphenylborate (NaTPB) was studied and improved performance was observed in several instances. Optimum performance was observed with membranes of (L1) having composition L1 : DBS : OA : PVC in the ratio of 6 : 54 : 10 : 30 (w/w, %). The sensor works satisfactorily in the concentration range 3.2 × 10-8-1.0 × 10-1 mol L-1 with a Nernstian slope of 29.5 ± 0.5 mV decade-1 of acu2+. The detection limit of the proposed sensor is 2.0 × 10-8 mol L-1 (1.27 ng mL-1). Wide pH range (3.0-8.5), fast response time (7 s), sufficient (up to 25% v/v) non-aqueous tolerance and adequate shelf life (3 months) indicate the utility of the proposed sensor. The potentiometric selectivity coefficients as determined by matched potential method indicate selective response for Cu2+ ions over various interfering ions, and therefore could be successfully used for the determination of copper in edible oils, tomato plant material and river water. [ABSTRACT FROM AUTHOR]

Eayrs, S., Hai, N. P., and Ley, J. 2007. Assessment of a juvenile and trash excluder device in a Vietnamese shrimp trawl fishery. – ICES Journal of Marine Science, 64: 1598–1602.In this study, we (i) identified why Vietnamese shrimp fishers land juvenile fish illegally; (ii) identified groups of fishers that would use a bycatch reduction device (BRD) to exclude these fish; (iii) studied the hydrodynamic performance of a juvenile and trash excluder device (JTED) in a flume tank; and (iv) assessed the performance of this device under commercial fishing conditions. Based on the responses of 65 fishers to a questionnaire, we found that juvenile fish are now an important economic component of the total catch, and that fishers operating larger boats were more willing to use a JTED to exclude these fish than fishers operating smaller boats. The hydrodynamic study of a JTED identified the location of low-velocity regions around the device and codend, and this information can be used to identify the location of a secondary BRD to allow more fish to escape. The at-sea assessment of this device found that 73% of juvenile fish, 16% of valuable fish, and 8% of shrimp were excluded by the JTED, although most valuable fish and shrimp were smaller than the minimum legal landing size. Overall, this loss represents a 9% reduction in revenue. Yield-per-recruit analysis indicated that this could be offset by not catching fish less than the minimum legal landing size. [ABSTRACT FROM PUBLISHER]

Fishers, scientists, and resource managers have made substantial progress in reducing bycatch of sea turtles, seabirds, and marine mammals through physical modifications to fishing gear. Many bycatch-avoidance measures have been developed and tested successfully in controlled experiments, which have led to regulated implementation of modified or new fishing gear. Nevertheless, successful bycatch experiments may not translate to effective mitigation in commercial fisheries because experimental conditions are relaxed in commercial fishing operations. Such a difference between experimental results and real-world results with fishing fleets may have serious consequences for management and conservation of protected species taken as bycatch. We evaluated preimplementation experimental measures and postimplementation efficacy from primary and gray literature for three case studies: acoustic pingers that warn marine mammals of the presence of gill nets, turtle excluder devices that reduce bycatch of turtles in trawls, and various measures to reduce seabird bycatch in longlines. Three common themes to successful implementation of bycatch reduction measures are long-standing collaborations among the fishing industry, scientists, and resource managers; pre- and postimplementation monitoring; and compliance via enforcement and incentives. [ABSTRACT FROM AUTHOR]

The alien mussel Mytilus galloprovincialis invaded sand banks in Langebaan Lagoon on the west coast of South Africa in the mid-1990s. However, by 2001 these beds had completely died off, with only empty shells and anoxic sand remaining. In an effort to prevent the re-settlement of this aggressive invader, all dead mussel shells were then cleared. This study considered the impacts of the invasion and subsequent die-off on natural benthic communities. Community composition differed significantly between non-invaded and invaded areas (ANOSIM, R = 0.685 and P < 0.01) as the physical presence of mussel beds created a new habitat that promoted invasion by indigenous rocky-shore species. This dramatically increased faunal biomass from 1,132.9 g m−2 ± 3,454.7 SD to 53,262.4 g m−2 ± 23,052.6 SD and species richness from 38 to 49 species. Following the die-off of the mussel beds, communities remained significantly different between non-invaded areas and those in which mussel shells remained (ANOSIM, R = 0.663 and P < 0.01). Species richness was significantly greater in non-invaded areas (18 species) than in uncleared areas with remnant shells (four species) (Kruskal–Wallis ANOVA H 2,36 = 10.8964 and P = 0.032), as the previously dominant rocky-shore species became smothered by sediment and the compacted shells formed an impermeable layer excluding sandy-shore burrowing organisms. After the shells were cleared, 50% of the sandy-shore species associated with non-invaded areas returned within 5 months, but community structure still remained significantly different to non-invaded areas (ANOSIM, R = 0.235 and P > 0.05). Invasion thus dramatically altered natural communities and although the subsequent removal of the dead mussel shells appears to have aided recovery, community composition remained different from the pre-invasion state after 5 months. [ABSTRACT FROM AUTHOR]

North Carolina fishery managers are considering methods to offer greater protection to the blue crab, Callinectes sapidus, spawning stock while maintaining a viable commercial fishery for female blue crabs in high salinity estuaries. We tested how effectively wire rectangles, or excluders, of two internal sizes, 45×80 mm and 45×90 mm, would prevent entry of ovigerous female (sponge) crabs into pots relative to control pots (without excluders) while maintaining sizes and catch rates of male and nonsponged female hard crabs. Field sampling among three pot designs (two excluder sizes and control pots) was conducted in Core Sound, N.C., during 2004-06. Median sizes (carapace widths) of mature female crabs were not different among the three pot types. However, median sizes of male crabs and sponge crabs were greater in control pots than pots with either size of excluder. Catch rates of mature female crabs from control pots were greater than from pots with 45×85 mm excluders. Catch rates of legal male and sponge crabs from control pots were greater than from pots with either size of excluder. Results indicate that using excluders involves a tradeoff between reducing catches and sizes of sponge crabs while also reducing sizes and catches of legally harvestable nonsponge crabs; moreover, the reduction in total catch and sizes would be greater for legal male crabs than for legal nonsponged female crabs. In high salinity waters close to North Carolina's existing no-harvest blue crab sanctuaries, where females typically dominate catches of hard crabs, the benefit of using excluders to prevent entry of sponge crabs may outweigh a potentially modest decrease in landings of nonsponged females. [ABSTRACT FROM AUTHOR]

The elutriation of fine particles (Group C or A particles in Geldart''s classification) from a fluid bed of mixed fine and coarse particles is investigated in a steady state. Al(OH)3 and alumina and TiO2 powder of 0.5–32 μm were used as fines. FCC, alumina, Al(OH)3, limestone, silica sand, SiC particles of 44–97 μm were used as coarse particles. The paper investigates the effect on the elutriation rate constant of both fine powders and coarse particles (i) of the weight fraction of Geldart C powders in the bed, (ii) of the superficial gas velocity, and (iii) of the size of C powder and size of coarse particles in the bed.The elutriation rate constant of group C or group A particles is not only affected by the properties of the elutriated powders or particles and gas velocity, but also by both the weight fraction and size of C powder in the bed. This finding differs from the elutriation result of A or B particles from a fluidized bed. [Copyright &y& Elsevier]

A dimensional analysis of the momentum balance in circulating fluidized beds reveals that their fluid dynamics is governed by five dimensionless groups. However, it is not possible to match the hydrodynamics of a range of industrial circulating fluidized beds using a single laboratory facility operated at ambient temperature and pressure.To address this difficulty, Glicksman et al. (Powder Technology 77 (1993) 177) proposed a “reduced set” involving only four dimensionless parameters. They showed that it is sufficient when the drag on solid particles conforms either to the viscous or to the inertial limit. They assumed that it would also succeed in the intermediate regime, where many industrial beds operate.We verify this assumption by comparing two series of experimental data obtained in the same facility with different combinations of gases and solids that preserve the “reduced set” but exhibit a mismatch of the complete five-parameter set of dimensionless numbers. We find that the dimensionless profiles of pressure along the flow and solid volume fraction in the radial direction are nearly identical in the two series of experiments. These observations validate the reduced scaling proposed by Glicksman et al. (1993) for the intermediate regime, at least for the simulated pressurized conditions of our experiments. [Copyright &y& Elsevier]

A new method of digital image analysis has been developed to study the hydrodynamics of two-dimensional bubbling fluidized beds with a digital video camera. The method comprises simultaneous of the size and velocity of gas bubbles, and the axial and radial distribution of bubble voidage. It provides a better estimation of the visible bubble flow than from local probe methods. Also a good estimation of the throughflow can be gotten, which is of great importance for combustor applications.Parallel to the approach of Darton et al. (Transactions of the Institution Chemical Engineering 55 (1977) 274) for three-dimensional fluidized beds, an equation for the bubble diameter of two-dimensional beds is developed,where h is the bed height above air distributor; t is the thickness of the two-dimensional bed. For Group B particle and a given gas velocity U0, if the bed height is sufficient, bubble diameter Db could be able to reach a maximum value at a certain height. The height is defined as the maximum bubble height h*, beyond which bubbles do not grow further and become unstable and break up. The height h* is a particle-size dependency, and can be expressed aswhere A=0.45 and Dt is the bed diameter. The bubble rising velocity Ub can be described bywithin the height h*. Also, the bubble velocity is kept constant beyond the height h*. The bubble density δb is not uniform over the bed cross-section. It increases with particle size, and increases quite slowly for high fluidization velocities. The gas throughflow decreases much slowly along with the bed height. Beyond the height h*, the gas throughflow is almost kept constant. Also, the throughflow is a significant part of the total gas flow, especially for high fluidization velocity, and increases almost linearly with the fluidization velocity. [Copyright &y& Elsevier]

Rhodoliths provide a stable and three-dimensional habitat to which other seaweeds and invertebrates can attach. Although ecological factors affecting rhodolith beds have been studied, little is known about the effect of rhodolith species and growth-form on associated fauna. Experiments were conducted at three rhodolith beds in the central-west Gulf of California. Faunal abundance differed significantly in relation to rhodolith-forming species, but no significant differences were observed between different growth-forms. Rhodolith structure differs between the species Lithophyllum margaritae and Neogoniolithon trichotomum, and the combination of structure differences and rhodolith abundances may be responsible of the significant differences in faunal abundance and richness. Crustaceans, polychaetes and molluscs were the most important taxa in all three rhodolith beds. The amphipod species Pontogeneia nasa and the cnidarian Aiptasia sp. were dominant in both rhodolith beds, El Requesón and Isla Coyote, in Bahía Concepción. The Isla Coronados rhodolith bed was dominated by an unidentified harpacticoid copepod (Copepoda sp.1). Rhodolith species is more important than growth-form in determining abundance and richness of the associated fauna. Nevertheless, factors such as wave motion, depth, bioturbation and others should be considered when studying organisms associated with rhodolith beds. [ABSTRACT FROM AUTHOR]

During the years of 1989 and 1990, the yield of the commercial fishery for the catarina scallop, Argopecten circularis (Sowerby, 1835), in Magdalena Bay, was 750 million organisms (5186t of muscles), which were gathered by diving at 12-30m depth. This production is the largest registered to date and accounted for 53% of the total Mexican scallop production since 1981. The formation of large beds in that area is a sporadic phenomenon which needs to be studied. In the present paper, a model to explain the formation of such beds is drawn, in which the bentho-pelagic red crab, Pleuroncodes planipes (Stimpson, 1860), plays a role as primary substrate for the recruitment of the spat and simultaneously is the active transporter of juveniles into the Bay during the winter months of cold years. Apparently exploitable beds are formed only when temperatures of 16°C or lower, are registered deep inside the Bay for at least 2 months. Relating these findings with short and long-term temperature fluctuations, it seems possible to predict future exploitable stocks in the area. [ABSTRACT FROM AUTHOR]

Experimental clearings, in macroalgal (Ascophyllum nodosum) stands were established in 1996 to determine if mussel beds and macroalgal stands on protected intertidal shores of New England represent alternative community states. Circular clearings 1, 2, 4, and 8 m in diameter were made in Ascophyllum stands at 12 sites on Swan's Island, Maine, USA. Each site also had an uncleared control. The sites are nested within four bays. The purpose of this data set is to provide access to data on densities and percent cover in the 60 experimental plots from 1996 to 2002. Data include densities of mussels (Mytilus edulis and Modiolus modiolus), an herbivorous limpet (Tectura testudinalis), herbivorous snails (Littorina littorea, Littorina obtusata), a predatory snail (Nucella lapillus), a barnacle (Semibalanus balanoides), and fucoid algae (Ascophyllum nodosum and Fucus vesiculosus), and percent cover by mussels, barnacles, and fucoids. Published analyses of the data set show that succession depends on clearing size and not on site-specific differences. [ABSTRACT FROM AUTHOR]