Hasil untuk "Aquaculture. Fisheries. Angling"

Xin Zhang, Xue Yang, Yuxuan Li et al.

Rotated object detection has made significant progress in the optical remote sensing. However, advancements in the Synthetic Aperture Radar (SAR) field are laggard behind, primarily due to the absence of a large-scale dataset. Annotating such a dataset is inefficient and costly. A promising solution is to employ a weakly supervised model (e.g., trained with available horizontal boxes only) to generate pseudo-rotated boxes for reference before manual calibration. Unfortunately, the existing weakly supervised models exhibit limited accuracy in predicting the object's angle. Previous works attempt to enhance angle prediction by using angle resolvers that decouple angles into cosine and sine encodings. In this work, we first reevaluate these resolvers from a unified perspective of dimension mapping and expose that they share the same shortcomings: these methods overlook the unit cycle constraint inherent in these encodings, easily leading to prediction biases. To address this issue, we propose the Unit Cycle Resolver, which incorporates a unit circle constraint loss to improve angle prediction accuracy. Our approach can effectively improve the performance of existing state-of-the-art weakly supervised methods and even surpasses fully supervised models on existing optical benchmarks (i.e., DOTA-v1.0 dataset). With the aid of UCR, we further annotate and introduce RSAR, the largest multi-class rotated SAR object detection dataset to date. Extensive experiments on both RSAR and optical datasets demonstrate that our UCR enhances angle prediction accuracy. Our dataset and code can be found at: https://github.com/zhasion/RSAR.

AK Yeoh, VH Hall-Chen, QT Pratt et al.

We introduce a new approach to measure the magnetic pitch angle profile in tokamak plasmas with Doppler backscattering (DBS), a technique traditionally used for measuring flows and density fluctuations. The DBS signal is maximised when its probe beam's wavevector is perpendicular to the magnetic field at the cutoff location, independent of the density fluctuations. Hence, if one could isolate this effect, DBS would then yield information about the magnetic pitch angle. By varying the toroidal launch angle, the DBS beam reaches cutoff with different angles with respect to the magnetic field, but with other properties remaining similar. Hence, the toroidal launch angle which gives maximum backscattered power is thus that which is matched to the pitch angle at the cutoff location, enabling inference of the magnetic pitch angle. We performed systematic scans of the DBS toroidal launch angle for repeated DIII-D tokamak discharges. Experimental DBS data from this scan were analysed and combined with Gaussian beam-tracing simulations using the Scotty code. The pitch-angle inferred from DBS is consistent with that from magnetics-only and motional-Stark-effect-constrained (MSE) equilibrium reconstruction in the edge. In the core, the pitch angles from DBS and magnetics-only reconstructions differ by one to two degrees, while simultaneous MSE measurements were not available. The uncertainty in these measurements was under a degree; we show that this uncertainty is primarily due to the error in toroidal steering, the number of toroidally separated measurements, and shot-to-shot repeatability. We find that the error of pitch-angle measurements can be reduced by optimising the poloidal launch angle and initial beam properties.

I. Buzevych, V. Gurbyk, О. Gurbyk

Purpose. To consider the environmental aspects of qualifying the degree of damage in some European Union countries and in Ukraine. To identify prospects for further development of Ukrainian methodological approaches to classifying offenses according to the basic principles of classifying damage, which require further development or improvement. Methodology. General scientific research methods were used to prepare the article, among which analysis, synthesis, generalization, induction, deduction, explanation should be noted. Findings. According to the results of the analysis of the legislation of some European Union countries, it was established that in the Federal Republic of Germany, the qualification of offenses is carried out in accordance with local legislation and is carried out according to the following criteria: catching fish without a license, during the spawning or wintering period, using prohibited fishing gears, preventing migration, transporting fishing gears outside the fishing grounds, and taking protected species. In the Kingdom of Spain, the qualification of offenses by the significance of the harm is carried out according to the following criteria: destruction of the distribution area, fishing during the spawning or migration period, harvesting of species whose fishing is prohibited, stocking (releasing) invasive fish species into natural water bodies, and violation of fishing rules. Ukraine provides for both criminal and administrative liability for poaching aquatic biological resources. Basic principles of qualification of damage caused to aquatic biological resources as a result of illegal fishing, animal or other aquatic exploitation, is qualified as significant according to the following criteria: taking fish or animals, the catching of which is prohibited, catching fish during the spawning period, taking a large number of fish, destroying rare species or those whose reproduction is difficult. Originality. Methodological aspects of qualifying the materiality of damage in Ukraine are highlighted for the first time. An analytical description of the legislation of some EU countries in the field of illegal fishing in their inland waters has been carried out. Practical Value. The basic principles of qualifying the materiality of damage are necessary to determine the type of liability resulting from illegal fishing of aquatic biological resources in the inland waters of Ukraine.

Lisong Chen, Syuhei Iguro, Yu Hamada

$μ$TRISTAN is a realistic high energy lepton collider based on the existing technology aiming at indirect and direct search for the physics beyond the standard model (SM). We propose a measurement to determine one of the most prominent parameters of the SM, weak mixing angle to test the SM and probe the new physics effect in Møller-like scattering with a wide range of interaction scales. We show that this experiment not only can determine the weak mixing angle with percent to milli-level accuracy but also scan over a wide range of interaction scales that have never been archived in a single experiment elsewhere.

Amarjit Soni

In the early 80's Sanda-san and collaborators wrote key papers on the direct and clean determination of the unitarity angle $φ_1$ ($β$). This motivated many of us for analogously coming up with ways for direct and clean determinations of the other two unitarity angles, $φ_2 (α)$ and $φ_3 (γ)$. Current status of these direct determinations as well as our expectations for when Belle-II has 50 $ab^{-1}$ of luminosity and LHCb with some upgrades, will be given. In particular, it is emphasized that for direct determination of $φ_3$, Belle-II should be able to handle final states in $D^0$ or $\bar D^0$ Dalitz decays, that contain one $π^0$ (which are difficult for LHCb) then they may make further inroads in improving the accuracy of $φ_3$ determination. Early lattice inputs for constraining the unitarity triangle (UT) are briefly recalled. Its crucial role in supporting the Kobayashi-Maskawa theory of CP violation is emphasized. Over the years lattice methods have made significant progress and latest constraints from these for the UT will be discussed as well as compatibility with current direct determinations and some comments on future outlook will be made.

Minh-Hoang Le, Minh-Hoang Le, Marit Espe et al.

IntroductionThis study explored the effects of increased water temperatures and limited feeding on the growth, feed utilization, and nutrient retention in juvenile cobia (Rachycentron canadum).MethodsJuvenile cobia, approximately 5.0 g in body weight, were distributed across two temperature conditions: 34°C, to mimic a global warming scenario, and 30°C, the current local summer average, as controls. The setup included eighteen 200-liter tanks, with 20 fish per tank. Within each temperature regime, triplicate tanks received one of three feeding levels (55%, 75%, and 95% of satiation as determined at 30°C) over a six-week period.ResultsThe findings indicated that cobia exhibited the poorest growth performance at the elevated temperature (34°C) and the lowest feeding level (55%). These conditions also correlated with the lowest protein efficiency ratio and feed intake. The feed conversion ratio worsened with increased temperature and feeding levels, while protein production values decreased at higher temperatures. A lower feeding level caused a lower total lipid retention but led to increased retention of whole body essential amino acids.DiscussionAfter six weeks, a 24-hour post-prandial analysis showed selective retention of some amino acids in muscle and plasma, but significantly higher retention in the liver at the higher temperature. Only a few amino acids' retention was influenced by feeding level. These results suggest that temperature and feeding levels alter the prioritization of amino acid metabolism and retention, as well as the utilization of energy and substrates across different organs of the cobia.

Nur Hidayah, Achmad Poernomo, Nadiah Ismi Rohadatul’aisy et al.

Ikan merupakan sumber protein yang dapat digunakan untuk fortifikasi dalam berbagai produk pangan. Untuk mempermudah proses, protein ikan dapat disediakan dalam bentuk hidrolisat bubuk atau hidrolisat protein ikan (HPI). Penelitian dilakukan untuk mengetahui jumlah  terbaik HPI dalam pembuatan cookies serta pendugaan daya awetnya. Cookies dibuat dengan variasi penambahan HPI 0% (kontrol), 5%, 10% dan 15%, dan konsentrasi terbaik ditentukan dengan uji hedonik oleh 30 panelis. Cookies dengan formula terbaik selanjutnya diuji mutunya (proksimat dan mikrobiologi) dan dilakukan pendugaan umur simpan menggunakan pendekatan kadar air kritis. Cookies dengan formula terbaik adalah dengan penambahan HPI 5%, dan memiliki nilai proksimat berupa kadar protein 7,38%, kadar lemak 14,19%, kadar air 4,09%, kadar abu 1,56% dan kadar karbohidrat 72,77% serta nilai ALT 2,56x103 kol/g; dengan perkiraan umur simpan 957 hari atau 2,62 tahun.

Luigi Piazzi, Lorenzo Pacciardi, Marco Pertusati et al.

Coralligenous reefs are calcareous structures edified mostly by coralline algae that characterize the circalittoral zone of the Mediterranean Sea. However, in some cases coralline algae can constitute peculiar infralittoral biogenic reefs which have been studied less than the circalittoral ones. This study aims to contribute to the knowledge of infralittoral coralligenous reefs by describing their macroalgal assemblages on a large rocky platform off the Tuscany coasts, northwestern Mediterranean Sea. To this end, a multifactorial sampling design was used to describe the structure of the assemblages and to evaluate the variability of the system at multiple spatial scales. A total of 71 macroalgal taxa were found on the coralline algae. Macroalgal assemblages were well structured, with high biodiversity values. The dominant taxa included both photophilous and sciaphilous species, guaranteeing peculiar characteristics in these assemblages, above all if compared with the typical infralittoral and circalittoral macroalgal communities of the same geographic area. The assemblages showed greater variability at a small and intermediate spatial scale than at a large scale. Although infralittoral coralligenous outcrops constitute a peculiar system, they are still poorly understood and should not only be the object of specific studies but also be included in monitoring programmes.

M. Gammanpila

The growth of marine bivalves is affected by the interactions of several environmental variables, particularly water salinity, temperature, and food supply. Influences of environmental parameters on daily weight gain (DWG), survival and heavy metal accumulation in 225 numbers of oysters, Crassostrea madrasensis (Preston, 1916), placed at five locations in the Negombo estuary, Sri Lanka, were investigated. One-way ANOVA indicated significantly higher (P < 0.05) DWGs (0.22 ± 0.01 and 0.16 ± 0.01 g.day-1) in Pitipana and Munnakaraya, where highest mean salinity (20.9 ± 0.34 ppt) and chlorophyll-a (5.41 ± 1.49 µg.L-1) were observed. Significantly lower growth rate (0.04 ± 0.02 g.day-1) recorded in Thaladuwa, where lowest salinity (13.29 ± 1.13 ppt), highest turbidity (19.26 ± 0.99 NTU) and ammoniacal nitrogen (0.368 ± 0.078 mg.L-1) were recorded. DWG showed a significant second-order polynomial relationships with chlorophyll-a (R² = 0.44, P < 0.05) and salinity (R² = 0.28, P < 0.05). Negative exponential relationships of DWG were evident with higher level of ammoniacal nitrogen (R² = 0.24, P < 0.05) and phosphate (R² = 0.25, P < 0.05). The high concentration of lead (1.883 mg.kg-1) exceeded the EU permissible limit of 1.5 mg.kg-1 (wet weight) in oysters’ tissue where urban wastewater is released to the lagoon. There appeared to be health concerns due to heavy metal accumulation in oyster tissues in polluted areas of the estuary. The findings of this study are useful for understanding the potential impacts of environmental changes on oyster resources and the long-term sustainability of oyster fisheries and aquaculture.

William M. Guimarães, Cristiano M. B. Cordeiro, Marcos A. R. Franco et al.

We propose and theoretically study a new hollow-core fiber-based curvature sensor with the capability of detecting both bending magnitude and angle (direction). The new sensor relies on a tubular-lattice fiber that encompasses, in its microstructure, tubes with three different thicknesses. By adequately choosing the placement of the tubes within the fiber cross-section, and by exploring the spectral shifts of the fiber transmitted spectrum due to the curvature-induced mode field distributions' displacements, we demonstrate a multi-axis bending sensor. In the proposed sensor, curvature radii and angles are retrieved via a suitable calibration routine, which is based on conveniently adjusting empirical functions to the sensor response. Evaluation of the sensor performance for selected cases allowed to determine the curvature radii and angles with percentual errors of less than 7%. The approach proposed herein provides a promising path for the accomplishment of new curvature sensors able to resolve both the curvature magnitude and angle.

Delia Rodríguez-Olague, Jesús T. Ponce-Palafox, Sergio G. Castillo-Vargasmachuca et al.

Indoor nursery systems are becoming increasingly popular for high-quality whiteleg shrimp production. These systems allow for a significant degree of control and management in a biosecure manner. However, it is still unclear as to what type of production system is best suited for indoor whiteleg shrimp nurseries. This study evaluated and compared clean-water recirculating aquaculture system (CW-RAS), photo-heterotrophic (PT), and biofloc technology (BFT) systems in terms of water quality, growth performance, and production costs of whiteleg shrimp Litopenaeus vannamei at three stocking densities (500, 1000 and 1500 org/m3) for 35 d in the nursery phase. In this study, twenty-seven, 100-L circular plastic tanks (microcosm) were randomly assigned to one of the treatments and stored with postlarvae shrimps (0.016 g). Throughout the experiment, water quality parameters remained within acceptable ranges for whiteleg shrimp growth. High concentrations of total ammonia-nitrogen (TAN) were determined in the CW-RAS system and nitrates and nitrites in the BFT system. Furthermore, the growth parameters showed significant differences (P < 0.05) between the treatments; higher values in PT and BFT systems at 500 org/m3 and lower survival in the CW-RAS system. These results suggest that a dense-dependent effect was observed from 1000 org/m3 onwards. In general, postlarvae, feed, labor and energy accounted for higher costs. The study findings further indicate that CW-RAS had the highest production costs for 1000 juveniles.

Li-Chao Zhuo, Dayang Nur Jazlyn binti Abang Zamhari, Annita Seok Kian Yong et al.

The main purpose of the agriculture circular economy is waste recycling with the intended goal of economic efficiency and environmental protection. In this study, the potential use of lemon peel, an agricultural waste, as a functional feed additive in aquafeed was evaluated by estimating the effects of fermented lemon peel (FLP) supplementation in diet on the growth, immune responses, and intestinal morphology of Asian sea bass, Lates calcarifer. Lemon peel was fermented by Lactobacillus plantarum. Basal diet was supplemented with 0%, 1%, 3%, and 5% FLP. Four experimental diets were each fed in triplicate to juvenile Asian sea bass (initial weight: 11.42 ± 0.39 g) in a recirculation rearing system for 8 weeks. Final weight, weight gain, feed intake, and survival were similar (p > 0.05) among all dietary treatments. Plasma lysozyme activity was higher in fish fed the diet with 3% FLP than that in fish fed the diet with 5% FLP. Hepatic thiobarbituric acid-reactive substance values were lower in fish fed diets with ≤3% FLP than that in fish fed the diet with 5% FLP. Fish fed diets with 1% and 3% FLP showed a tight lamina propria (LP) in microvilli compared with fish fed diets with 0% and 5% FLP. The microvilli area/height ratio was higher in fish fed diets with 0% and 5% FLP than that in fish fed diets with 1% and 3% FLP. The minimum level obtained from the second-order polynomial regression model were 0.26 % for microvilli area and area/height ratio. Results indicate that diets supplemented with 1 %–3 % fermented lemon peel can improve intestinal health for Asian sea bass. However, 5% FLP supplementation may lead to low immune response and high oxidative stress.

G. Turchini, Pin Nie

It is December 2020, the year is almost at its end with the world is still facing the effects of COVID-19 and its resulting disruption. Simultaneously, a series of interesting scientific debates concerning the possible unexpected side-effects of pandemic management on climate change are now proliferating. Wishes and hopes have been expressed about the possible temporary benefits of a partial reduction in greenhouse gas emissions. The possibility to use the anticipated recovery phase as a platform to transform the current challenges into opportunities to transit towards a more sustainable world is now a new prospective priority. Whilst we have no reason not to be optimistic when it comes to the current pandemic, we have to note that climate change, with its resulting effects on ocean warming, ocean acidification, extreme and unpredictable weather conditions, rising sea levels and salinity variations, is still happening. We should not be distracted from maintaining a focus on these phenomena which are directly impacting the aquaculture sector. In addition to the immediate and logical effects that such changes could have on aquaculture activities and practices, there are two, somewhat unexpected, effects that have been put forward in recent publications. The first one pertains to the alarming association between antimicrobial resistance in aquaculture-related bacteria and warmer temperatures that has been recently reported by Reverter et al. (2020). Whilst the authors of this study clearly outline that the causes and effects of this association are still numerous, unclear and complex, it can be argued that the existing changing environmental conditions on farms are increasing the occurrence of conditions favouring disease outbreaks and therefore favouring an increased application of antimicrobial agents. This observation is a somewhat unpredicted consequence of how climate change can further affect aquaculture, and – with a cascade effect – generating a series of possible secondary effects on environmental and societal health. This observation is prompting further impetus towards the R&D efforts of the aquaculture sector in the development and refinement of possible solutions and climate change adaptation remedies. When the relocation of a farm to an area with more suitable environmental conditions, or the adoption of new cultured species better equipped to cope to the new conditions is not possible, other remedial strategies must be identified. These can span from improved – and more cost-effective – vaccination strategies, to the implementation of targeted selective breeding, the use of adaptive nutrition strategies, the identification and effective use of bioactive compounds, probiotics and other immune stimulants, which can all contribute in reducing the occurrence of diseases outbreaks, and therefore minimising the use of antimicrobial agents. What is evident is that increased knowledge, targeted research activities and solutions are needed, as the climate is still changing, and aquaculture needs to adapt. The second recent observation of another unexpected effect of climate change, which could directly affect aquaculture, arises from a study by Colombo et al (2020), who hypothesised that global warming could significantly reduce the availability of the health-promoting omega-3 long-chain polyunsaturated fatty acid and docosahexaenoic acid (DHA). This is because the de novo synthesis of DHA in algae, which sit at the base of aquatic food chains, could reduce when temperature increases. DHA is an extremely important nutrient, with a plethora of physiological roles and health-promoting effects in animals and in humans. Currently, considering the constantly increasing share of aquaculture over wild fisheries on the total fish and seafood availability, aquaculture is possibly the largest source of edible DHA for humanity. However, aquaculture is also a user of this precious nutrient, which is already in relatively short supply. Several strategies have been developed and are at different stages of implementation and commercialisation to reduce the dependence of aquaculture on wild-derived DHA, traditionally coming from fish meal and fish oil from wild fisheries. These comprise of improved aquafeed formulations and feed management strategies, new raw materials containing omega-3 long-chain polyunsaturated fatty acids, such as single cell oils and the oil extracted from GM oilseed crops, nutritional programming and selective breeding, shifts to aquaculture species with more efficient in vivo DHA biosynthetic capabilities and other approaches in earlier stages of development. Nevertheless, the impact of climate change on global DHA availability will further exacerbate this problem, and aquaculture must face the challenge of delivering this health-promoting nutrient to humans, whilst significantly reducing its utilisation from wild-derived sources. Again, what is evident is that increased knowledge, targeted research activities and

A. Sylvia, Brandon Maahs, M. Weber

Tournament anglers typically possess extensive knowledge of the habitat and seasonal movement of their targeted species. While fish‐angler behavioral relationships are critical to understand fish catchability, few studies have assessed how fish behavior influences their vulnerability to capture by tournament anglers. Our objectives were to determine if Largemouth Bass Micropterus salmoides behavior, angler behavior, and environmental conditions affect tournament angler catch rate (CPUE) and bass capture probability at fishing tournaments. Forty‐nine bass were tracked weekly using radio telemetry during a four‐month period. Five tournament anglers were also selected at weekly tournament events and tracked continuously using a handheld GPS unit. We quantified individual bass behaviors (home range, weekly movement rate, depth use, and spatial overlap with anglers), angler behaviors (depth use, angler movement rate), and environmental conditions (air and water temperature) and used these estimates as covariates in a multiple regression model to assess their effects on tournament CPUE and then used a multistate mark‐recapture model to estimate bass capture probability at tournaments. Our results indicate that bass movement rate, angler fishing depth, and air temperature were highly correlated to tournament angler CPUE. Mark‐recapture models also indicated air temperature and angler‐bass overlap were positively associated with bass capture probability while bass total length, home range, movement rate, and depth use were not successful in characterizing individual variation in capture probability. Our results indicate that bass that are encountered by anglers are more likely to be captured. Whereas, mismatches between angler and bass behavioral factors including depth use and movement rates may result in decreased tournament capture rates. Consideration and continued evaluation of the relationships between bass and angler behaviors and environmental variables is critical to fisheries management as tournament pressure paired with high capture probabilities and selective angling can have large‐scale population level impacts.

Sandeep Joy, Saad Khalid, Brian Skinner

When light is incident on a medium with spatially disordered index of refraction, interference effects lead to near-perfect reflection when the number of dielectric interfaces is large, so that the medium becomes a "transparent mirror." We investigate the analog of this effect for electrons in twisted bilayer graphene (TBG), for which local fluctuations of the twist angle give rise to a spatially random Fermi velocity. In a description that includes only spatial variation of Fermi velocity, we derive the incident-angle-dependent localization length for the case of quasi-one-dimensional disorder by mapping this problem onto one dimensional Anderson localization. The localization length diverges at normal incidence as a consequence of Klein tunneling, leading to a power-law decay of the transmission when averaged over incidence angle. In a minimal model of TBG, the modulation of twist angle also shifts the location of the Dirac cones in momentum space in a way that can be described by a random gauge field, and thus Klein tunneling is inexact. However, when the Dirac electron's incident momentum is large compared to these shifts, the primary effect of twist disorder is only to shift the incident angle associated with perfect transmission away from zero. These results suggest a mechanism for disorder-induced collimation, valley filtration, and energy filtration of Dirac electron beams, so that TBG offers a promising new platform for Dirac fermion optics.

Matías Schwartz, Silvana Campodónico

Se procedió a describir el desarrollo larval temprano de la vieira patagónica (Zygochlamys patagonica) que se obtuvo de los desoves de las temporadas de verano 2015 y 2017. Los desoves se obtuvieron por inducción con las técnicas de limpieza valvar y shock térmicos (7 y 13 °C) en 16 vieiras adultas de entre 55 y 72 mm de alto de valva, sexualmente maduras y en igual proporción de sexos. El agua de los recipientes de inducción se filtró con tamiz de 35 mm para retener los ovocitos fecundados que se colocaron en recipientes de 2 l con agua oceánica a 7 ± 0,5 °C y sin aireación. Se observaron y midieron los estadios de desarrollo temprano hasta larva trocófora y se registró la duración de cada fase y el tipo de movimiento. El desarrollo embrionario se completó con el estadio de gástrula 30-40 h posteriores a la fecundación. La fase de larva trocófora comenzó a las 80-84 h, estadio en que se produjo la mortalidad total de las larvas. Si bien no se completó el ciclo de vida de Z. patagonica, el presente trabajo constituye el primer registro de desarrollo larval temprano de la especie, necesario para conocer el tiempo que la larva pasa en la columna de agua y, por lo tanto, su capacidad de dispersión.

Mei‐Jie Yang, Hao Song, Zheng‐Lin Yu et al.

The veined rapa whelk, Rapana venosa (Valenciennes, 1846), is an important and valuable fishery species; however, it has not been routinely artificially cultured on a large scale. Here, we studied the effect of temperature (6, 16, 22 and 28°C) on the digestive enzymes in R. venosa of different sizes (Juvenile (small, S: 1.2–1.8 cm) and adult (medium, M: 4.1–5.2 cm; large, L: 7.6–8.9 cm)) by detected the enzyme activity in different digestive glands (the salivary gland, Leiblein's gland (oesophageal gland) and liver) using spectrophotometric method, to determine the optimal temperature for artificial cultivation and to explore the feeding habits of this whelk. The optimal temperature was determined to be approximately 22°C. The food intake was significantly higher at 22°C than at other temperatures, and the activity of the digestive enzyme, trypsin, was at the highest in the main digestive gland of R. venosa, the liver, at 22°C. In addition, the observed presence of cellulase and α‐amylase may suggest that carbohydrates are necessary during R. venosa development. The results of this study will help in the formulation of technical procedures for R. venosa aquaculture and in preventing its overexploitation, and explained its invasion mechanism to some extent.

Sumit Kumar, Pawan Kumar, Sunando DasGupta et al.

The pinning of the contact line adversely influences the electrowetting performance of sessile liquid droplets. In this paper, we report the electrowetting hysteresis characteristics of 100 mM aq. KCl sessile liquid droplet placed on a hydrophobic PDMS surface. The effect of nanoparticles on the contact angle hysteresis under the imposed electric potential is further investigated. This study reveals that the contact angle hysteresis decreases beyond a certain threshold value of nanoparticles concentration. Therefore, nanoparticle suspension in the liquid droplet can be used to enhance or suppress the electrowetting hysteresis and consequentially rate of heat transfer during hot spot cooling.

William M. Goldsmith, A. Scheld, J. Graves

The Atlantic Bluefin Tuna Thunnus thynnus is the target of a recreational fishery along the U.S. East Coast that is thought to be of considerable economic value. In some years, recreational landings have exceeded the sector’s annual subquota due to changes in fish availability, limited predictability of angler effort, and difficulties in real-time monitoring of catch. Understanding the drivers of angler behavior is critical for predicting how effort and harvest may vary as a function of changing fish availability, regulations, or costs. To investigate angler decision making, preferences, and values, we surveyed private recreational anglers from Maine to North Carolina and employed discrete choice experiments to determine how regulatory and nonregulatory trip-specific variables influence trip-taking behavior. A latent class-ranked logit model identified two distinct classes of anglers who exhibited differing preferences in regard to the importance of nonconsumptive aspects of Bluefin Tuna fishing (e.g., catch and release). Income and recent Bluefin Tuna targeting were the primary determinants of class membership, and higher-income anglers who had targeted Bluefin Tuna in the past 5 years were significantly more likely to be in the class that derives substantive benefits from nonconsumptive angling activities. An annual consumer surplus exceeding US$14 million was estimated for the 2015 fishery. We considered potential angler welfare impacts of possible management changes (compensating surplus) and identified a large amount of latent effort currently present in the fishery in the form of consumptiveoriented anglers. As a result, liberalization of harvest regulations could potentially lead to a large influx of effort into the fishery, which could impede the ability of managers to maintain harvest levels within prescribed limits. Over the past several decades, resource management scholars have advocated for better integration of the social sciences into fisheries management (Voiland and Duttweiler 1984; Fenichel et al. 2013). Understanding the human component of fisheries is important for predicting how management actions will affect the well-being of fishery participants, as well as for informing the allocation of fishery resources among competing user groups (Orbach 1980). In addition, without properly understanding the preferences and motivations of anglers, predicting behavioral responses (e.g., effort and harvest) is difficult and can potentially undermine management’s effectiveness and threaten a fishery’s sustainability (Fulton et al. 2011; Fenichel et al. 2013; Hunt et al. 2013). Fishing behavior may, for example, change as stock status or management strategies change, and simply extrapolating past behavior under different conditions could lead to inaccurate predictions (Fulton et al. 2011). Furthermore, while determining the preferences and motivations of recreational anglers is challenging (compared with commercial fishers, who are often thought to be largely motivated by profit), understanding drivers of angler behavior for a given fishery is critical for *Corresponding author: william.m.goldsmith@gmail.com Received December 3, 2017; accepted March 14, 2018 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. North American Journal of Fisheries Management 38:680–697, 2018

S. Kiyama, S. Yamazaki

Understanding behavioral responses of resource users to environmental changes and incentives created by management systems is imperative to implement effective resource management and development policies. A small-scale mixed fishery in the Maizuru Bay, Japan, provides a natural experiment to evaluate changes in small-scale fishers’ harvesting and targeting behavior over the years that one of the key species in the fishery experienced a collapse of the stock. Using data on individual fishers across the pre- and postcollapse periods, we find that inefficient fishers were forced to shut down or stay idle along with the collapse of the stock, and this behavior led to an increase in the overall efficiency in the production of clams (Venerupis philippinarum). The depletion of the stock, however, imposed a natural constraint on the operation, resulting in a substantial decline in the maximum production achievable by the remaining fishers. We further show that the collapse of the stock not only affected the harvesting behavior against the declining species but also led to the expansion of the fishing capacity and effort to catch other species and the development of aquaculture as an alternative form of fish production in the region.