Although laboratory studies have confirmed horizontal transmission of white spot syndrome virus (WSSV) among decapod crustaceans, its transmission dynamics in practical aquaculture remains poorly understood. This study investigated WSSV transmission from infected Procambarus clarkii to Eriocheir sinensis in a simulated polyculture environment. A 15-day outdoor pond experiment (120 m²) was conducted by co-culturing WSSV-infected crayfish with healthy crabs. Our results demonstrated successful cross-species transmission, with highest viral loads in gills and muscle tissues. Female crabs showed significantly higher susceptibility to infection than males. Physiological analysis revealed elevated oxidative stress markers in infected crabs, including increased superoxide dismutase activity and malondialdehyde levels. Molecular analysis showed upregulation of immune-related genes (anti-lipopolysaccharide factors, crustin, prophenoloxidase) in gills and muscle, indicating innate immune activation. We observed distinct tissue-specific responses: in male muscle, viral replication was associated with Nrf2 pathway activation and autophagy suppression, while gills tissues exhibited apoptosis potentially limiting viral spread. Plankton community shifts were also documented, with increased diatom and ciliate abundance but decreased green and golden algae in WSSV-infected waters. This study provides direct evidence of WSSV transmission between economically important crustacean species under practical aquaculture conditions, highlighting the disease risks in polyculture systems and the need for strict carrier screening.
Catch-and-release regulations in recreational fisheries have been implemented for decades with the intention of allowing fishing while reducing fishing mortality. In addition, voluntary catch-and-release behaviors are increasingly common. Social and scientific interest in fish handling practices in catch-and-release fisheries as they relate to stress, reflex impairment, reproductive success, and mortality has been expanding. The scientific literature is now replete with studies that examine these issues, and they have become a fixture in the public discourse on angling. Scientists and anglers are making fishing regulation proposals and suggestions for fish-handling practices. The proximal intent of these recommendations is to reduce excessive stress or mortality on a per capita basis with a belief that the reduction ultimately has a positive effect on the population. Whether the proximal intent achieves population goals depends on several factors, including effort, population dynamic rates, and stock-recruitment dynamics. This perspective reviews the state of the science relative to a hierarchical framework of fishery population dynamics, with a call for fishery scientists to consider their scope of inference and assumptions relative to conservation and population management.
Brown Trout Salmo trutta are commonly stocked in high-order rivers to create recreational fisheries and supplement naturalized populations. At temperate latitudes in New England, most larger rivers present climate-driven physiological challenges for Brown Trout. Understanding the movement and survival of Brown Trout poststocking in these systems can inform more effective stocking practices that maintain angling opportunities. We radio-tagged 80 Brown Trout total and stocked them in the Housatonic River, Connecticut, in fall 2021 and spring 2022. We quantified Brown Trout net movements and used a series of linear mixed-effects and Cormack–Jolly–Seber models to determine riverscape habitats and conditions influencing movement and survival during each season. After release, 67.5% and 42.5% of individuals were never relocated during fall and spring, respectively. Remaining fall-stocked fish exhibited higher mean net movements (3.25 km) than spring fish (0.75 km). Fall stocking results were influenced by a 100-year flood event. Linear mixed-effects models were constructed separately for fall and spring on data from relocated fish, and proximity to deep pools and thermal refuges emerged as covariates associated with Brown Trout net movements. Cormack–Jolly–Seber models estimated mean cumulative apparent survival of stocked Brown Trout as 0.11 (95% CI = 0.01–0.18) during fall and 0.33 (0.19–0.44) during spring. Discharge, water temperature, and time since stocking influenced both apparent survival and detection probabilities during both seasons. Our study documented substantial fish loss from the stocking area, particularly following a flood event shortly after stocking. Among fish that remained in the stocking area, movement patterns resembled those observed in lower-order rivers, though survival rates were comparatively lower. Consideration of stocking locations proximate to deep-pool and thermal refuge habitats merit more investigation, as increased variability in discharge and temperature are expected to continue to challenge stocking programs.
Patrick Kawaye Chimseu, Samson Pilanazo Katengeza, Emmanuel Kaunda
et al.
ABSTRACT Use of digital tools is rapidly transforming the world, and Information and Communications Technology (ICT) integration in fisheries presents great opportunities for enhancing fishing‐dependent livelihoods. This article employed latent class analysis and a multinomial logistic regression to explore preferred digital tools for fish traders to address the problem of lack of access to market information. Results from a sample of 548 participants show heterogeneous preferences among fish traders who can be classified into three subgroups: digital‐wise (70%), phone‐wise (24%) and digital‐local (6%) across different platforms and prefer the use of all platforms (USSD, calls, apps, radio and television [TV] programmes). On the basis of platform ranking, traders prefer calls more, followed by app, USSD, radio and TV, respectively. Results further show that social demographic characteristics, including marital status, gender, age and trust among players, influence class membership in different subgroups. To address the diverse needs of traders, there is a need for a free, cross‐platform digital system, call centre/USSD service for convenience, data quality checks, endorsements, the provision of digital credit and stakeholder collaboration to exploit digital fish trade opportunities for Malawi to benefit from the African Continental Free Trade Agreement and not to be left behind in the fourth industrial revolution.
The precise assessment of the gonad status and gamete development level is an essential step in abalone breeding. However, traditional methods are damaging to the animals, causing the waste of a quality parent. Ultrasound imaging as a noninvasive technique is a candidate substitute. This study aimed to verify the application of ultrasonography to the assessment of abalone gonad condition. Pacific abalones (n = 20) were randomly selected for ultrasonography, another six abalones in different gonad maturation stages (mature, between mature and immature, and immature) were also subjected to the same detection and histological analysis. Abalones (n = 10) were induced to spawn, and the changes in the gonad index and the types of germ cells were determined before and after spawning. Thirty-six female abalones were selected and divided into a high-gonad index group (HGI) and a low-gonad index group (LGI) according to the gonad index determined by ultrasonography, and their reproductive performance was compared during the entire breeding process. There was no significant difference in gonad index or gonad relative average thickness (GRAT) obtained from ultrasonography and histological methods. The gonad index and GRAT measured by ultrasound images significantly decreased after spawning. After spawning, a minimal quantity of mature gametes remained in gonad tissue as reflected in histology images. In a reproductive trial, the HGI group showed comprehensive and overwhelming reproductive advantages compared to the LGI group in total fecundity, relative fecundity, fertilization rate, hatching rate, abnormality rate, and attachment rate. Ultrasonography was demonstrated to be useful as a noninvasive method to evaluate abalone gonad condition. The ultimate goal is to achieve tracing and monitoring the abalone reproductive cycle through the ultrasound technique.
Wettability quantifies the affinity of a liquid over a substrate, and determines whether the surface is repellent or not. When both the liquid and the solid phases are made of the same chemical substance and are at thermal equilibrium, complete wetting is expected in principle, as observed for instance with drops of molten metals spreading on their solid counterparts. However, this is not the case for water on ice. Although there is a growing consensus on the partial wetting of water on ice and several estimates available for the value of the associated contact angle, the question of whether these values correspond to the equilibrium angle without thermal effects is still open. In the present paper, we address this issue experimentally and demonstrate the existence of a macroscopic contact angle of water on ice using theoretical arguments. Indeed, when depositing water droplets on smooth ice layers with accurately controlled surface temperatures, we observe that spreading is unaffected by thermal effects and phase change close enough to the melting point. Whereas the short time \C{motion of the contact line} is driven by an inertial-capillary balance, the evolution towards equilibrium is described by a viscous-capillary dynamics and is therefore capillary - and not thermally - related. Moreover, we show that this contact angle remains constant for undercoolings below 1 K. This way, we show the existence of a non-zero equilibrium contact angle of water on ice, that it is very close to 12$^\circ$. We anticipate this key finding to significantly improve the understanding of capillary flows in the presence of phase change, which is especially useful in the context of ice morphogenesis and of glaciology, but also in the aim of developing numerical methods for resolving triple-line dynamics.
میلاد زعفرانی تبریزی, سید مهدی اجاق, معظمه کردجزی
et al.
در این طرح نخست به مقدار لازم (150 کیلوگرم) انواع پسماند (ماهی ساردین کامل، باله سفره ماهی، سر ماهی شیر، سر ماهی هوور، سر ماهی گیدر، سر ماهی خاویاری، پوست ماهی خاویاری) از مراکز فرآوری ماهی جمعآوری شدند و به آزمایشگاه منتقل گردیدند. در مرحله بعد با آب آشامیدنی شسته شده، در محلول سود با نسبت 1 به 10 به مدت 2 ساعت قرار گرفته، سپس از محلول خارج شده و با آب آشامیدنی بصورت کامل شستشو داده شدند. برای قرار گرفتن در محلول اسید استیک با نسبت 1 به 10 به مدت سه ساعت آماده گردیدند. بعد از پایان شستشو پسماند کاملا با آب آشامیدنی شسته شده، به نسبت 1 به 10 با آب مقطر در ظرف استیل ادغام و درون آون با دمای 60 درجه سلسیوس قرار گرفتند. بعد از 8 ساعت ظرف خارج شده و پسماندها از داخل آن با استفاده از فیلتر و پنبه جدا سازی گردیدند. محلولهای ژلاتینی با استفاده از حرارت به حجم نصف رسانده شدند و تغلیظ صورت گرفت، سپس محلول تغلیظ شده درون سینی های استیل ریخته و درون خشک کن با دمای 50 درجه سلسیوس قرار گرفتند. در پایان پولکهای خشک شده ژلاتین به آسیاب منتقل شده و پودر گردیدند. در مرحله نهایی برای آنالیزهای استاندارد به آزمایشگاه استاندارد فرستاده شدند. نتایج بدست آمده بیانگر این بود که ژلاتین-های پوست ماهی خاویاری، سر ماهی خاویاری و سر ماهی گیدر دارای کیفت فیزیکو شیمیایی، و حسی و استاندارد مناسب-تری نسبت به دیگر پسماندها بوده و قابلیت تولید در مقیاسهای بزرگتری را دارند.
Mysids have become the preferred diet for Sepia and Hippocampus breeding due to their nutritional content and size. Despite their potential as a high-quality feed, limited literature exists on the specific nutritional needs of N. orientalis and how diet influences their reproduction. This study investigated the effects of various diets—Corethron sp., Chlorella sp., mixed algae, and flakes—on the survival, total reproductive output, and whole tissue nutritional composition of N. orientalis. The main results were as follows: 1) N. orientalis fed with Corethron sp. exhibited the highest survival (90.11 ± 5.09% at 14 d; 57.78 ± 5.09% at 21 d); 2) Significant differences in total reproductive output were observed among the dietary groups, with the mixed diet group showing the highest output (121.67 ± 5.03 ind), followed by the Corethron sp. group (102.67 ± 3.51 ind); 3) Principal component analysis revealed that the nutritional composition of mysids predominantly comprises C18:2n-6, C22:6n-3, Σn-3 PUFA, Asp, Glu, Val, Phe, and TAA; 4) Correlation analysis indicated a strong positive correlation between the dietary C18:2n-6 and Σn-3 PUFA and the survival and total reproductive output of N. orientalis. Additionally, the dietary C20:4n-6 and C20:5n-3 showed a strong positive correlation with the C22:5n-3 and Σn-3 PUFA in N. orientalis. A similar strong positive correlation was observed between dietary amino acids and those in mysids. In conclusion, the study demonstrates that different diets directly influence the nutritional composition of mysids, affecting their survival and total reproductive output during the breeding period. Consequently, Corethron sp. emerges as a suitable diet for N. orientalis, enriching C20:5n-3 and Σn-3 PUFA, which fulfills the nutritional requirements of N. orientalis during their reproductive period, thereby enhancing individual survival and reproduction.
There is a procedure, due to Dani and Levcovitz, for taking a finite simplicial graph (Γ) and a subgraph (Λ) of its complement, checking some conditions, and, if satisfied, producing a graph (Δ) such that the right-angled Artin group with presentation graph (Δ) is a finite index subgroup of the right-angled Coxeter group with presentation graph (Γ). They do not tell us how to find (Λ), given (Γ). We show, in the 2--dimensional case, that the existence of such a (Λ) is connected to the graph property of satellite-dismantlabilty of (Γ), and we use this to give an algorithm for producing a suitable (Λ) or deciding that one does not exist.
We outline a practical scheme for converting between three commonly used sets of phases to describe the trajectories of extreme mass ratio inspirals; quasi-Keplerian angles, Mino time action-angles, and Boyer-Lindquist time action-angles (as utilised by the FastEMRIWaveform package). Conversion between Boyer-Lindquist time action angles and quasi-Keplerian angles is essential for the construction of a source frame for adiabatic inspirals that can be related to the source frames used by other gravitational wave source modelling techniques. While converting from quasi-Keplerian angles to Boyer-Lindquist time action angles via Mino time action-angles can be done analytically, the same does not hold for the converse, and so we make use of an efficient numerical root-finding method. We demonstrate the efficacy of our scheme by comparing two calculations for an eccentric and inclined geodesic orbit in Kerr spacetime using two different sets of orbital angles. We have made our implementations available in Mathematica, C, and Python.
Fisheries and fish supply are undergoing a fundamental structural transition, as indicated by a ten country analysis. Aquaculture now provides around half the fish for direct human consumption and is set to grow further, but capture fisheries continue to make essential contributions to food and nutrition security throughout the global South. Capture fisheries provide diverse, nutritionally valuable fish and fish products which are often culturally preferred and easily accessed by the poor. Technological changes in aquaculture have dramatically increased fish supply, lowered relative fish prices, and reigned in price volatility. Policies that recognize and safeguard the diversity and complementarity of roles played by capture fisheries and aquaculture are needed to ensure that the transition in fisheries sustainably improves food and nutrition security in the global South.
Bibek S. Dhami, Vasudevan Iyer, Aniket Pant
et al.
Coupling between light and matter strongly depends on the polarization of the electromagnetic field and the nature of the excitations in the material. As hybrid perovskites emerge as a promising class of materials for light-based technologies like LEDs, lasers, and photodetectors, understanding the microscopic details of how photons couple to matter is critical. While most optical studies have focused on the spectral content and quantum efficiency of emitted photons in various hybrid perovskite thin-film and nanoscale structures, few studies have explored other properties of the emitted photons such as polarization and emission angle. Here, we use angle-resolved cathodoluminescence microscopy to access the full polarization state of photons emitted from large-grain hybrid perovskite films with spatial resolution well below the optical diffraction limit. Mapping the Stokes parameters as a function of the emission angle in a thin film, we reveal the effect of a grain boundary on the degree of polarization and angle at which the photons are emitted. This exploration of angle- and polarization-resolved emission near grain boundaries provides an improved understanding of the emission properties of hybrid perovskites in thin film geometries -- a necessary investigation for subsequent engineering of subwavelength nanophotonic structures using the hybrid perovskite class of materials.
Poul H. Damgaard, Jitze Hoogeveen, Andres Luna
et al.
Scattering angles for probes in Kerr metrics are derived for scattering in the equatorial plane of the black hole. We use a method that naturally resums all orders in the spin of the Kerr black hole, thus facilitating comparisons with scattering-angle computations based on the Post-Minkowskian expansion from scattering amplitudes or worldline calculations. We extend these results to spinning black-hole probes up to and including second order in the probe spin and any order in the Post- Minkowskian expansion, for probe spins aligned with the Kerr spin. When truncating to third Post-Minkowskian order, our results agree with those obtained by amplitude and worldline methods.
Casper Gundelund, R. Arlinghaus, H. Baktoft
et al.
Abstract Citizen science platforms, including smartphone applications, that allow anglers to report information about fishing trips and catches may be a low-cost source of data that can feed into the science and management of recreational fisheries. However, information about potential biases in these data, such as the representativeness of user characteristics and retention patterns is largely lacking. Here, we examine the characteristics and retention patterns of the users of a Danish citizen science smartphone application and website that allow anglers to report data from fishing trips. Using data from a roving creel survey of sea trout (Salmo trutta) anglers as an independent source for calibration, we found that users of the citizen science platform were younger, more specialized, and had higher catch rates than non-users. On the citizen science platform, 21% of the users were active (i.e., contributed data at least once, three months after creating an account), with an additional 22% using the platform as a source of information (e.g., catch statistics or regulations) for at least three months. These sustained users were older and ascribed a higher importance to angling as a hobby compared to those who stopped using the platform within three months. Data from similar platforms are unlikely to be representative of all anglers and, as a result, research is required to determine what issues this will bring for population extrapolations.
Responsible aquaculture, the farming of aquatic organisms, is a sustainable strategic sector for land and coastal communities. It significantly contributes to food security and enhancement of economic development; it provides employment opportunities and often contributes to the ecological services provided by the environment. According to the Food and Agriculture Organization of the United Nations (FAO), the contribution of aquaculture to the global food security is widely demonstrated by an astounding industry growth of 7.5% per year since 1970. In 2018, aquaculture reached the all-time highest production of 114.5 million tonnes in live weight with a total farm gate sale value of USD 263.6 billion. This makes aquaculture a key player within the Blue Growth concept and a strong contributor to some of its key Sustainable Development Goals (SDG). This is particularly true in geographical areas where dependence of local economies on fishery products is high, and yet access to sustainable landings is hampered by ecological barriers. One such area is represented by the Black Sea basin. Whilst the Black Sea annual capture fishery production has varied considerably since 1990 and its current landings are significant, growing attention is currently given to boost aquaculture development along the Black Sea bordering countries, with marine aquaculture being considered as an important contributor to the total fisheries production. Nonetheless, aquaculture development in this region is not homogenous and its development has, so far, been limited by environmental, economic, social, and more generally governance issues. This paper, for the first time, attempts to provide a comprehensive fresh outlook of the aquaculture sector in the Black Sea, stressing the importance of regional cooperation as an essential pillar to support the sustainable development of the industry. The paper addresses aquaculture in the Black Sea from different perspectives: it outlines the key characteristics of the Black Sea environment; it discusses the most common farmed aquatic species and the potential for new ones; it frames the national approaches to aquaculture development, sharing information about success stories, while shedding light on the main challenges and priorities ahead. This collective endeavour will represent a helpful contribution to Black Sea riparian countries to answer the many questions they have, and expectations they hold from the aquaculture sector.
Worldwide bivalve aquaculture is expanding rapidly. Simultaneously, there has been a loss of natural bivalve reefs due to anthropogenic activities. As bivalve reefs support several ecosystem functions disproportionate to the area they cover, there is interest in their restoration. The Firth of Thames (FoT) in northern New Zealand once supported dense populations of green lipped musselsPerna canaliculus, which were extirpated by a dredge fishery in the mid-20thcentury. Efforts to restore these biogenic habitats are underway. The largest standing populations of this species in the area currently exist in aquaculture. This study aimed to determine if larval spill-over from aquaculture can provide a larval subsidy to bivalve reef restoration efforts in the FoT. We used a combination of trace elemental fingerprinting and biophysical modelling techniques to determine patterns of larval dispersal in the area. Results of both approaches indicated that the larval pool in the area is well mixed with larvae produced at aquaculture locations capable of settling throughout the study area. Overall this shows, for the first time, that larval spill-over from aquaculture may provide a subsidy to restoration efforts and assist with establishing sustainable populations. When determining restoration locations, the potential for aquaculture populations to act as a larval source should be explicitly considered. Conversely, when considering the location of new aquaculture sites, the consequences of larval spill-over to surrounding wild populations should be assessed. We recommend that restoration efforts and aquaculture be carefully integrated in a network approach which could provide both ecological and economic benefits.