Harvesting Strategies Research Articles

Ecological and economic predictors of métiers in a mixed fishery

Abstract Marine ecosystem-based management requires the understanding of species interactions and what species are harvested together. This study combines two major questions: the first regarding what drives the probability that a métier (species assemblages, with spatial distribution and seasonality) will be observed as catch, and the second regarding the level of control fishers have over this catch mix. To address these questions, we analysed highly resolved logbook records of an Arctic and sub-Arctic industrial demersal fishery operating in Icelandic waters. The study employs a multi-class random forest model to identify predictors of métier occurrence and consistency of predictions using a dataset of >100 000 hauls over 4 years (2016–2019). The overall accuracy of the random forest model is 69–70%, indicating moderate predictability of catch mix based on known environmental, vessel, and company characteristics. We find that habitat-related variables (depth and temperature) are most important to predict catch mix. Still, company, trip, and vessel characteristics are also very important (e.g. vessel and trip length, distance to port). Beyond these more traditional bio-economic variables, important predictors include variables related to harvesting strategies, such as quota diversity and a vessel’s mobility. These findings contribute to a fuller picture of fisher decision-making in mixed fisheries.

A Cost-Benefit Analysis of Alternative Management Strategies for Red Deer in Denmark

In this paper, we conduct a cost-benefit analysis (CBA) of five alternative management strategies for red deer in Denmark: free harvest, trophy hunting, maximum harvest and two cases for natural demographic population compositions. To capture the outcome under each strategy we use a biological sex- and age-structured population model. The net benefit function includes meat values, recreational values, browsing damage costs and traffic damage costs and these values and costs are assumed to differ for the various sex and age classes of red deer. We show that the maximum harvest strategy leads to a reasonably high positive total net benefit, while the free harvest strategy yields a small positive net benefit. On the other hand, the trophy hunting strategy generates a high negative net benefit, while small negative net benefits are obtained under the two strategies for natural demographic population compositions.

Alfalfa‐bermudagrass mixtures managed under contrasting harvest strategies in the southeastern US

AbstractThe incorporation of dual‐purpose alfalfa (Medicago sativa L.) cultivars into bermudagrass (Cynodon spp.) is a viable option to extend the grazing season in Southern forage systems. However, data are limited on which harvest management strategy (HMS) optimizes the use of alfalfa‐bermudagrass (ABG) mixtures in the Southern US. A two‐year study evaluated ABG mixtures under three HMS [cut only (CO), graze only (GO), or cut and graze (CG)].in Headland, AL and Tifton, GA. Alfalfa‐bermudagrass mixtures utilized in this evaluation were ‘Bulldog 805’ alfalfa that was interseeded into ‘Tifton 85’ bermudagrass. Treatments were evaluated for forage, animal, and total system performance. Herbage accumulation varied by year and location (p < .01), but the number of harvests ultimately determined the total forage produced. Forage allowance was never limiting but did differ among treatments at Tifton, GA (p = .02). The CG HMS allowed for similar daily (p > .06) and liveweight gains (p > .56) on fewer days of grazing as compared to the GO treatments. The greater alfalfa percentage in the CG HMS translated to greater total digestible nutrients (TDN) and crude protein (CP), though not always statistically different. The CO HMS maximized system performance when evaluated for total gain (actual gains + predicted gains). However, the CG management allowed for more production opportunities across the season, thereby reducing economic risk. Future research should focus on evaluating the economic implications of introducing each HMS into ABG systems.

Bioeconomic analysis of deterministic and stochastic partial harvesting in the production of spring genetics tilapia variety restricted to minimum market sizes

A bioeconomic model was used for commercial tilapia culture to evaluate different partial harvest strategies. This study considered homogeneous and heterogeneous seeding sizes. The impact of one and two partial harvests was evaluated. In the first case 25% of the population was harvested (I), in the second 50% (II), in the third 25% and 25% (III), and in the fourth 50% and 25% (IV). Four minimum market sizes were considered: 350, 400, 450, and 500 g. The results indicated that a first partial harvest of 25% or 50% of the population as well as two partial harvests with a homogeneous seeding sizes generated the highest net benefits, with US$3954.32 and US$4303.52 at a minimum market sizes of 500 g. Mortality rate, mean water temperature, feed cost and product price were considered as sources of uncertainty and were simultaneously analyzed in the bioeconomic model using Monte Carlo analysis. An initial partial harvest of 25% of the population followed by two partial harvests with a homogeneous seeding sizes and a minimum market sizes of 500 g presented the lowest uncertainty and an expected loss of 32.84% and US$0.00, respectively. An initial partial harvest of 50% of the population as well as a partial harvest with a heterogeneous seeding sizes presented the lowest uncertainty (31.97%), while two partial harvests with a homogeneous seeding sizes presented the lowest expected loss of US$-2.09, in both cases with a minimum market sizes of 500 g. It provides relevant information to the producer for decision-making in the management of seeding and harvesting, to improve their economic, considering minimun market sizes.

The photothermal properties of hydrogel nanocomposite embedded with ZnO/CuO based on PVA/GA/activated carbon for solar-driven interfacial evaporation

Using the renewable energy, especially solar energy, is an environmental-friendly approach for seawater desalination. Solar evaporation is a promising freshwater harvesting strategy rich in energy, including solar and water energy. Herein, we propose a solar evaporation hybrid hydrogel including polyvinyl alcohol (PVA) and glutaraldehyde (GA) as a polymer network, semiconductor oxide nanoparticles (ZnO, CuO) and activated carbon as a photothermal material. Structural properties of hybrid hydrogel were characterized by X-ray diffraction (XRD) analysis, surface morphology by field emission scanning electron microscope (FE-SEM), chemical bonding by Fourier transform infrared spectroscopy (FTIR) and optical absorption and absorption coefficient (α) of components by UV–Vis spectroscopy. The result showed in visible region, PVA:ZnO:AC hydrogel nanocomposite has a strong absorption (55%) compare of the PVA:CuO:AC hydrogel nanocomposite (35%). In addition, by distillation measurements, the evaporator system demonstrated for PVA:CuO:AC and PVA:ZnO:AC Hydrogel an evaporation rate of 2.29 kg m−2 h−1 and 5.19 kg m−2 h−1 with the evaporation efficiency of 30.66% and 70.80%, respectively, under 0.1 sun irradiation. For PVA:CuO:AC hydrogel, the hardness of Caspian seawater decreased from 6648 to 115 ppm and ion conductance from 8641 (μS) to 244 (μS) and for the PVA:ZnO:AC Hydrogel decreased to 97 ppm and ion conductance to 206 (μS). Experiments showed that with changing type of the ZnO or CuO semiconductor oxide nanoparticles can effectively on regulate the optical properties of the evaporator. Eventually, this work begins a new point of synthesizing cost-effective photothermal absorbers based on metal oxides material and activated carbon nanocomposite.

Advancing Non-Line-of-Sight Communication: A Comprehensive Review of State-of-the-Art Technologies and the Role of Energy Harvesting.

Enhancing spectral efficiency in non-line-of-sight (NLoS) environments is essential as 5G networks evolve, surpassing 4G systems with high information rates and minimal interference. Instead of relying on traditional Orthogonal Multiple Access (OMA) systems to tackle issues caused by NLoS, advanced wireless networks adopt innovative models like Non-Orthogonal Multiple Access (NOMA), cooperative relaying, Multiple Input Multiple Output (MIMO), and intelligent reflective surfaces (IRSs). Therefore, this study comprehensively analyzes these techniques for their potential to improve communication reliability and spectral efficiency in NLoS scenarios. Specifically, it encompasses an analysis of cooperative relaying strategies for their potential to improve reliability and spectral efficiency in NLoS environments through user cooperation. It also examines various MIMO configurations to address NLoS challenges via spatial diversity. Additionally, it investigates IRS settings, which can alter signal paths to enhance coverage and reduce interference and analyze the role of Unmanned Aerial Vehicles (UAVs) in establishing flexible communication infrastructure in difficult environments. This paper also surveys effective energy harvesting (EH) strategies that can be integrated with NOMA for efficient and reliable energy-communication networks. Our findings show that incorporating these technologies with NOMA not only enhances connectivity and spectral efficiency but also promotes a stable and environmentally sustainable data communication system.

3D spacer fabric structured airflow channel for enhanced solar desalination with efficient multi-energy harvesting

Solar steam generation (SSG) is a sustainable way to drive seawater desalination and wastewater purification with green environmental energies including solar radiation, ambient heat, and airflow. Airflow is ubiquitous in outdoor environments, however, the utilization of airflow for accelerated evaporation through structure engineering remains unclear. Herein, environmental energies are efficiently utilized in an integrated way with the rational design of 3D spacer fabric. Carbon fiber bundles with broadband photothermal conversion ability and Tencel yarns with superior hydrophilicity are fabricated into the 3D spacer fabric. The stereoscopic airflow channel, wide evaporation surface area, and separated layers are constructed to optimize airflow pathways. Heat loss is reduced through the accelerated evaporation cooling effect. Extra ambient heat is harvested for cold evaporation by efficient airflow utilization. The evaporation rate of 3D spacer fabric reaches 5.15 kg·m−2·h−1 under a convective airflow of 3.5 m·s−1, which is twice the rate of traditional plain fabrics. The outstanding salt resistance is realized due to the separate design of photothermal and water supply layers as well as the continuous water circulation. The structural engineering of condenser devices is also investigated for enhanced airflow utilization. Overall, this work presents an effective and comprehensive multi-energy harvesting strategy to achieve rapid and durable SSG for practical clean water production.

Pacific tuna update: 20th Meeting of the Western and Central Pacific Fisheries Commission

The Western and Central Pacific Fisheries Commission (WCPFC), the governing body for the world’s largest tuna fishery, held its 20th annual Commission meeting in Rarotonga, Cook Islands, in December 2023. This commentary provides an overview of the meeting and its outcomes. Revisions to the tropical tuna measure were the main focus of member states’ attention, alongside the determination of an interim Target Reference Point for South Pacific albacore, compliance monitoring reporting, and updates to measures and harvest strategies for Northern Stocks. The members were able to comprehensively address the management of the tropical tuna species and made progress on harvest strategies. Harvest strategies are pre-determined management actions that would reduce the reliance on short-term management decisions and achieve a long-term management framework. However, other important issues, such as developing an allocation framework, remained unresolved despite the member's commitment to start developing such a framework at this year’s meeting. Emerging shifts in meeting dynamics were observed and may signal changes in how the WCPFC operates moving forward.

Effects of grass species and harvest date on cell wall components and feed efficiency of dairy cows

There is a balance between DM yield and feed value when choosing types of grasses on a farm depending on the acreages of farmland and types of ruminants to be fed. Therefore, optimisation of the harvest strategy for grass silage is important for profitable dairy farming. Tall fescue has high DM yield and can replace traditional grasses, such as timothy, in Northern Europe in a changing climate as it has been shown to be more drought tolerant. As differences in climate responses previously have been related to differences in cell wall structure between grass species and, consequently, in digestibility, it is highly relevant to compare these species at similar maturity stages and to investigate if a very early harvest date will diminish potential differences between the species. This study evaluated the effects of harvest date and forage species on the concentration of hydroxycinnamic acids in silages and its relationship to feed efficiency of dairy cows. Tall fescue and timothy were harvested at very early date on May 25 or at early date on May 31 in the spring growth cycle. Forty lactating dairy cows were used in a block design. Cows received 1 of 4 treatments: (1) tall fescue harvested at very early date, (2) timothy harvested at very early date, (3) tall fescue harvested at early date, and (4) timothy harvested at early date. Diets were formulated to have the same forage-to-concentrate ratio (49:51 on DM basis). Tall fescue silages showed greater concentrations of DM, ash, and CP than timothy silages. Grasses harvested at early date showed greater concentrations of NDF, ADL, and cell wall than grasses harvested at very early date. Tall fescue silages showed greater concentration of p-coumaric acid and lower in vitro organic matter digestibility (IVOMD) compared to timothy silages. Milk production and composition were not affected by treatments but cows fed tall fescue-based diets showed lower milk protein yield and greater milk urea nitrogen than when timothy-based diets were fed. Furthermore, cows receiving timothy-based diets showed greater feed efficiency compared to cows receiving tall fescue-based diets. Thus, the lower concentration of p-coumaric acid and the higher IVOMD was associated with greater feed efficiency of cows fed timothy-based diets compared to tall fescue-based diets.

Green pepper fruits counting based on improved DeepSort and optimized Yolov5s.

Green pepper yield estimation is crucial for establishing harvest and storage strategies. This paper proposes an automatic counting method for green pepper fruits based on object detection and multi-object tracking algorithm. Green pepper fruits have colors similar to leaves and are often occluded by each other, posing challenges for detection. Based on the YOLOv5s, the CS_YOLOv5s model is specifically designed for green pepper fruit detection. In the CS_YOLOv5s model, a Slim-Nick combined with GSConv structure is utilized in the Neck to reduce model parameters while enhancing detection speed. Additionally, the CBAM attention mechanism is integrated into the Neck to enhance the feature perception of green peppers at various locations and enhance the feature extraction capabilities of the model. According to the test results, the CS_YOLOv5s model of mAP, Precision and Recall, and Detection time of a single image are 98.96%, 95%, 97.3%, and 6.3 ms respectively. Compared to the YOLOv5s model, the Detection time of a single image is reduced by 34.4%, while Recall and mAP values are improved. Additionally, for green pepper fruit tracking, this paper combines appearance matching algorithms and track optimization algorithms from SportsTrack to optimize the DeepSort algorithm. Considering three different scenarios of tracking, the MOTA and MOTP are stable, but the ID switch is reduced by 29.41%. Based on the CS_YOLOv5s model, the counting performance before and after DeepSort optimization is compared. For green pepper counting in videos, the optimized DeepSort algorithm achieves ACP (Average Counting Precision), MAE (Mean Absolute Error), and RMSE (Root Mean Squared Error) values of 95.33%, 3.33, and 3.74, respectively. Compared to the original algorithm, ACP increases by 7.2%, while MAE and RMSE decrease by 6.67 and 6.94, respectively. Additionally, Based on the optimized DeepSort, the fruit counting results using YOLOv5s model and CS_YOLOv5s model were compared, and the results show that using the better object detector CS_YOLOv5s has better counting accuracy and robustness.

Securing water for arid regions: Rainwater harvesting and sustainable groundwater management using remote sensing and GIS techniques

Arid regions experience climatic stress under climate change: increased drought frequency coupled with intensified storm events. This disruption and lack of precipitation patterns leads to water scarcity and hinders the achievement of sustainable development goals. Egypt drainage basin exhibiting the greatest suitability for the implementation of rainwater harvesting (RWH) strategies. To facilitate the development of sustainable water resource management practices in the region, this study uses a multi-criteria methodology to delineate optimal zones for RWH within the Wadi Safaga. Integration of radar and optical remote sensing data obtained from Sentinel-1&2, Landsat-8, ALOS/PALSAR, and Sentinel-1 Interferometric SAR with climatic Tropical Rainfall Measuring Mission (TRMM), hydrological, and geological datasets emphasizes the hydrologic characteristics of the catchments. Additionally, the analysis of rainfall intensity patterns within the basin was undertaken. Thirteen factors are used in the predicted model including elevation, slope, curvature, depression, lithology, radar, InSAR CCD, drainage density (Dd), distance to river (DR), vegetation, topographic wetness index (TWI), rainfall, and lineament density. A knowledge-driven Geographic Information System (GIS) methodology, including weighted factors based on the Analytical Hierarchy Process (AHP), was implemented to delineate plausible areas for RWH and groundwater potential zones (GWPZs). The resultant map categorized the basin into five GWPZ classes: very low (14%), low (28%), moderate (27%), high (21%), and very high (10%). Furthermore, the study identified optimal locations for constructing reservoirs to store harvested rainwater and provide protection for downstream mining, industrial, and tourism activities. In conclusion, the obtained information is crucial for planners and decision-makers to implement sustainable water resource management strategies within the Wadi Safaga basin.

A model-based approach for formal verification and performance evaluation of energy harvesting architectures in IoT systems: A case study of a long-term healthcare application

Energy harvesting plays a significant role in the Internet of Things (IoT). Indeed, although numerous approaches exist to limit the system’s power consumption, the energy provided by the battery remains constrained, thereby limiting the system’s lifetime. Energy harvesting represents an interesting technique that allows a set of devices in an IoT architecture to operate for a potentially infinite time without the need for battery replacement or recharge. This work presents a formal modeling framework for the performance evaluation of energy harvesting architectures and strategies in IoT systems. We present a model-based approach using UPPAAL to model and analyze IoT device lifetimes and capture the energy-related behavior of nodes and various energy harvesters. Furthermore, the model is calibrated using measurements acquired from real-life IoT applications to demonstrate the effectiveness of the proposed model and its ability to investigate various energy-related aspects.

Predictability of ecological and evolutionary dynamics in a changing world.

Ecological and evolutionary predictions are being increasingly employed to inform decision-makers confronted with intensifying pressures on biodiversity. For these efforts to effectively guide conservation actions, knowing the limit of predictability is pivotal. In this study, we provide realistic expectations for the enterprise of predicting changes in ecological and evolutionary observations through time. We begin with an intuitive explanation of predictability (the extent to which predictions are possible) employing an easy-to-use metric, predictive power PP(t). To illustrate the challenge of forecasting, we then show that among insects, birds, fishes and mammals, (i) 50% of the populations are predictable at most 1 year in advance and (ii) the median 1-year-ahead predictive power corresponds to a prediction R 2 of only 20%. Predictability is not an immutable property of ecological systems. For example, different harvesting strategies can impact the predictability of exploited populations to varying degrees. Moreover, incorporating explanatory variables, accounting for time trends and considering multivariate time series can enhance predictability. To effectively address the challenge of biodiversity loss, researchers and practitioners must be aware of the information within the available data that can be used for prediction and explore efficient ways to leverage this knowledge for environmental stewardship.

Optimal Harvesting Strategies for Timber and Non-Timber Forest Products with Nonlinear Harvesting Terms

Optimal Harvesting Strategies for Timber and Non-Timber Forest Products with Nonlinear Harvesting Terms

First steps in restoring Río de la Plata grasslands: the importance of harvest method and season

Current trends in agricultural intensification lead to degraded grasslands, requiring their restoration through native species reintroduction. Various techniques are available for harvesting seeds from donor sites. However, little is known about their performance in South American C3/C4 mixed grasslands, where studies are scarce. Their particular species composition and phenology, with different flowering periods, require specific harvest strategies. We evaluated mechanical seed harvest in a northern Uruguay grassland, part of Río de la Plata grasslands. Performance of two mechanical harvest methods (seed‐stripper and dry hay) was compared in two harvest seasons (late‐spring and mid‐summer). The evaluation considered the quantity and identity of harvested seeds, and their germination in a greenhouse. Hand collections were made to assess standing seed yield. For each seed mixture, efficiency of mechanical harvests (number of seeds and seedlings compared to hand collection), proportion of germinated seeds, species transfer relative to donor site, and composition were calculated. Results revealed trade‐offs between harvests: seed‐stripper in late‐spring presented low seed collection efficiency (2% for seeds, 5% for seedlings) and species richness (43% transfer), but high seed germination (64%), showing selectivity toward winter species; seed‐stripper in mid‐summer and dry hay in both seasons showed high seed collection efficiency (42–154% for seeds, 26–50% for seedlings) and species richness (65–80% transfer), resembling donor site, albeit lower seed germination (9–20%). Seed‐stripper performance varied between seasons, while dry hay remained consistently effective. These results are pioneering for grassland restoration in Uruguay, encouraging future studies to focus on establishment in the field.

Clean water harvesting and power generation by solar-absorbing Germanium@k-carrageenan evaporator demonstrating superior energy conversion

The deterioration of climate exacerbates the freshwater crisis. Solar-thermal interfacial evaporation, using sunlight as a driving energy source, is a promising approach to provide an effective solution to freshwater shortages. However, the low energy conversion efficiency and expensive evaporator manufacturing are still to be resolved. Herein, a strategy of clean water harvesting by solar-absorbing germanium@k-carrageenan (Ge@CA) evaporator demonstrating superior energy conversion is proposed. The Ge nanoparticles exhibit a significant solar absorption of 92.33% to achieve efficient solar-thermal conversion. The CA hydrogel provides three-dimensional water transmission channels to the evaporating surface. Meanwhile, the Ge nanoparticles can be fabricated by a facile ball-milling method. The CA as a cheap biomass can be easily interacted with KCl to obtain the porous hydrogel. Taking the advantages of Ge nanoparticles and CA hydrogel, the Janus-type Ge@CA hydrogel evaporator can achieve an evaporation rate of 2.88 kg m−2·h−1 and a solar-vapor conversion efficiency of 82.65% under 1 sun irradiation. Furthermore, the evaporator can produce thermoelectricity with the output voltage of 140.95 mV and the short-circuit current of 13.32 mA, yielding a power of 1.17 W m−2. This reported solar device has huge potential for cutting-edge solar harvesting and usage.

Does Soil Acidification Matter? Nutrient Sustainability of Timber Harvesting in Forests on Selected Soils Developed in Sediments of the Early vs. Late Pleistocene

With this study, our aim was to estimate the nutrient fluxes relevant for assessing nutrient sustainability as accurately as possible and to calculate nutrient balances for alternative forest management scenarios. Furthermore, we tested whether mapping units from existing geologic maps can serve as a basis for forest practitioners to estimate nutrient sustainability or whether more detailed data are needed. Positive fluxes include deposition and weathering, while negative fluxes include losses due to leaching and nutrient removal through timber harvesting in the balance. Weathering and leachate losses were modeled with a geochemical model. The SwissStandSim model was used to simulate the biomass growth under different harvesting and silvicultural strategies, allowing for sustainability to be assessed for each nutrient at a given intensity of use. This assessment was made per rotation period based on two criteria: (i) nutrient supply and (ii) total stocking volume. As a result, it can be noted that the accurate estimation of individual fluxes is essential for assessing the sustainability of forestry practices and that it needs detailed site-specific data. Various influencing factors turned out to be important, particularly the assumed depth of the root zone.

First development of transparent wood-based triboelectric nanogenerator (TW-TENG): Cooperative incorporation of transparency, aesthetic of wood, and superior triboelectric properties

The combination of triboelectric nanogenerator (TENG) and wood-based materials offers a sustainable strategy for energy harvesting. The main challenge in realizing wood-based TENG is to increase the polarizabilities of wood. Herein, we introduce the first instance of a transparent wood-based triboelectric nanogenerator (TW-TENG), which synergistically incorporates superior triboelectric properties, optical properties, and aesthetic of wood. Addressing the challenges of weak polarizability and opacity inherent in natural wood, we propose a functionalized modification approach involving delignification and impregnation with UV-curable resin. In this study, leveraging delignification and the strong electron-donating groups within the UV-curable resin, the electrical output performance of TW-TENG is improved by 6.5 times compared to that of natural wood, and maintains stability over 10,000 operational cycles. Moreover, the matching refractive index between the UV-curable resin and the wood substrate offers TW-TENG with high transparency, achieving an optical transmittance of up to 88.8 %, exhibiting the unique aesthetic value of transparent wood. Furthermore, we demonstrate the potential applications of TW-TENG in energy harvesting, sensor technologies, smart decorative materials, smart home systems, and beyond, exemplified through its utilization in electrical output generation by pressing, capacitor charging and discharging, and self-powered multiplexed sensing smart target shooter.

The impact of pollution reduction on the optimal harvesting strategy in a seasonally changing and polluted environment

The impact of pollution reduction on the optimal harvesting strategy in a seasonally changing and polluted environment

High-Entropy Ceramics Enhanced Droplet Electricity Generator for Energy Harvesting and Bacterial Detection.

The droplet electricity generator (DEG) is a solid-liquid triboelectric nanogenerator with transistor-inspired bulk effect, which is regarded as an effective strategy for raindrop energy harvesting. However, further enhancement of DEG output voltage is necessary to enable its widespread applications. Here, high-entropy ceramics are integrated into the design of DEG intermediate layer for the first time, achieving a high output voltage of 525 V. High-entropy ceramics have colossal dielectric constant, which can help to reduce the triboelectric charge decay for DEG. Furthermore, the effect of factors on DEG output performance when employing high-entropy ceramics as the intermediate layer is extensively analyzed, and the underlying mechanisms and mathematical models are explored. Finally, the enhanced output voltage of DEG not only facilitates faster energy harvesting but also develops a novel method for rapid bacterial detection. This work successfully integrates high-entropy ceramics into DEG design, significantly enhances the output voltage, and offers a novel direction for DEG development.