ABSTRACT The processes that lead to the capture of marine organisms in fishing gear are inherently complex, arising from interactions between the deployment of fishing effort, gear efficiency, and species‐specific demography and behaviour. A mechanistic understanding of these processes provides a principled basis for developing management approaches that explicitly account for how different gears interact with different species. Here, we present a general framework for fishing that decomposes capture into the sequential processes of encounter, contact, and retention. We demonstrate how these processes give rise to the emergent properties of catchability and selectivity under varying conditions. Using a set of examples drawn from fish farming, towed gears, and static gears, we show that a common conceptual framework can be applied across diverse fishing contexts, and that the resulting dynamics of catch are consistent with empirical observations. The framework provides a consistent interpretation of fishing effort across gear types and helps to relate existing definitions of fishing processes within a common structure. By synthesising concepts that have traditionally been treated separately in fishing gear technology and stock assessment, this framework provides a flexible basis for incorporating additional biological, technological, and behavioural processes. As such, it offers new insights into how management measures and fishery interactions influence the capture of fish and other marine organisms, with broader implications for fisheries management and ecosystem‐based approaches.
Natural capital accounting provides a framework for integrating ecological processes with economic valuation, but the mechanics of shadow price formation often remain opaque to resource managers and policymakers. Using the Clarks Fork elk herd in northwestern Wyoming as a case study, we decompose the shadow price of natural capital into its ecological, economic, and institutional components. Population dynamics are estimated using a linearized Ricker model and projected forward using a logistic projection, incorporating climate-driven reductions in intrinsic growth rates. These ecological scenarios are linked to a shadow pricing formulation that explicitly accounts for marginal benefits, harvest policy responses, discounting, and capital gains. Results show shadow prices are shaped by population size, nonlinear ecological feedbacks, and scarcity expectations. Climate-induced declines in intrinsic growth rates dampen both biological growth and capital gains, attenuating the steepness of shadow price declines relative to population losses. Isolating the effects of marginal benefits, discounting, and capital gains sheds light on how ecological change shapes scarcity-adjusted value, improving the interpretability of natural capital accounting.
Ecological and infection predator prey mathematical model is important tool for understanding complex systems and forecasting outcomes biologically. Incorporating saturation mass action incidence rates representing the rate of susceptible prey infection as a function of time along with time delay terms, makes more realistic and reflective of the inherent dynamics in the real-world systems. This study develops and analyzes delayed ecology model with disease where prey is infected by microparasites, and the predator consume both susceptible and diseased prey. The infection process is assumed to involve a constant time delay, referred to as the infection delay, while the predator reproduction following prey consumption introduces another delay, known as the gestation delay. Qualitative analysis of the model is verified. The consequence of delay terms in the model on the stability of the coexistence fixed point is investigated by treating the delay as a bifurcation parameter. The results indicate the existence of Hopf bifurcation and stability switching as delay cross a certain critical threshold values. Finally, we performed numerical simulations using ODE 45 and DDE 23 codes to support the theoretical and qualitative results in agreement with numerical findings.
As one of the international economic organizations, the G-7 countries are composed of the world's leading industrialized countries. In addition, the role of the G-7 countries in global warming is another issue that is constantly debated. Concerns have been raised about these very wealthy nations' capacity to manage their resources sustainably. Examining the factors that contribute to efficient resource management in these nations has grown in significance. The goal of this research is to look at how eco-friendly innovations, clean energy transition, economic development, and trade affect effective resource management in the G-7 nations. The material footprint is used as a gauge for efficient resource management. The Method of Moments Quantile Regression (MMQR) approach, which is a novel method, was used in this research to examine the G-7 nations' yearly data for the years 1990-2019. Eco-friendly technologies lower the material footprint in the G-7 nations, according to MMQR findings. Results are statistically significant for the majority of quantile levels (0.1-0.7). Clean energy transition also reduces the material footprint of the G-7 countries, with statistically significant results at all quantile levels. Economic development increases the material footprints of G-7 countries; findings are statistically significant at all quantile levels. The material footprint is consequently increased by trade, and the results are statistically significant at various quantile levels (0.5-0.9). Additionally, the research tests robustness using other panel estimators and achieves similar findings. Lastly, the paper offers policy suggestions for G-7 nations' efficient resource management.
Temperature is an important factor affecting daily life, and accurate multi-step temperature prediction can provide essential support for weather prediction, energy management, agricultural planning, and disaster mitigation. However, as the prediction horizon extends, the nonlinear nature of temperature data becomes more prominent, making it increasingly difficult to accurately model temporal variation patterns. Regarding this issue, this paper proposes a multi-step temperature prediction system which comprises a multi-frequency information extraction subsystem and a high-precision prediction subsystem. The multi-frequency information extraction subsystem employs a decomposition-clustering-reconstruction strategy to obtain high, medium, and low-frequency data from the original temperature data. In the high-precision prediction subsystem, we employ an encoders-decoder architecture with an adaptive weighting mechanism to extract features from multi-frequency data and produce prediction results. In addition, to further enhance prediction accuracy, time-frequency domain fusion is applied during training to capture differences between predictions and actual values from multiple angles. To evaluate the performance of the prediction system, three sets of comparative experiments are conducted on four datasets, demonstrating that the proposed system outperforms other benchmark models.
Tradable quotas support efficiency and value creation in fisheries. Quota values can provide useful information in several aspects, as they are related to the resource rent and may figure in estimates of natural capital. Further, willingness to pay for quota can shed light on management tradeoffs. Quotas in the Norwegian groundfish fishery are, however, not traded on an open market platform, and prices are not generally known. Based on a model for the spatiotemporal distribution of catch for Norwegian trawlers, providing an estimate for operational profits, I calculate marginal values of changes in the quota holding of a representative vessel. For example, willingness to pay for a metric ton of cod quota is roughly NOK 80,000. The inferred willingness to pay is dependent on existing quota levels, and is conditional on binding quotas for bycatch species. The dependence on existing quota levels is different when bycatch quotas are non-binding. The calculations presume that the quota is added to a vessel with available capacity such that no additional fixed or capital costs are necessary. The underlying model represents the planning problem of a fisher faced with quotas for several species, when prices vary over time and catch-per-unit-effort varies over time and between areas.
In this study, we introduce a mathematical ecology model that describes the interactions among forest biomass, the human population, various development activities, and seedlings. The study applies modified Leslie-Gower and Holling type II functional responses to capture these interactions. Quantitative analyses, such as the existence and stability of potential equilibrium points, are examined. These points represent the different dynamics that may occur within the model. The persistence of the system is established, indicating that the ecosystem can sustain itself over time despite interactions such as competition or disturbances. The presence of a Hopf bifurcation near an equilibrium point is also confirmed. Data for this study were collected from two forest areas in Wonsho Woreda, Sidama Regional State, Ethiopia. The data were fitted to the model, and the parameters were estimated using the least squares method. Based on the estimated parameters, the results were validated through numerical simulations performed using the MATLAB ODE solver ode45. The findings show that forest biomass declines as the human population increases and as development activities expand. Conversely, increasing seedling application and promoting alternative resources lead to a higher equilibrium level of forest resources.
This study investigates how natural resources, productive capacities, climate resilience, green innovations, and education influence ecological sustainability in China. Using annual data from 2001 to 2023, we apply the Fourier ADF and Fourier ARDL approaches to capture nonlinear dynamics and smooth structural breaks often missed by traditional time-series models. Robustness is confirmed through FMOLS, DOLS, and CCR estimators. The results indicate that green innovations exert the strongest positive influence on ecological sustainability, followed by climate resilience and productive capacities, while over-exploitation of natural resources significantly undermines environmental quality. Education also contributes positively, reinforcing the long-term role of human capital development in sustainable ecological transitions. These findings emphasize the need for policies that expand innovation capacity, enhance climate readiness, and strengthen resource governance. The study contributes new evidence on sustainability drivers using Fourier-based econometrics and offers actionable insights for designing education-centered, innovation-driven, and resource-efficient development strategies aligned with China's SDG commitments.
Land use conversion entails trade-offs across multiple ecosystem services of wildlife. Wildlife is often characterized by spatiotemporal dynamics that affect this trade-off. The aim of this paper is to examine the net benefits from changes in the land use composition, given the consequences for the benefits provided by a harvested migratory prey species. The study is applied to land use and roe deer hunting in Sweden. We examine the spatial dynamics of land use, predator populations, prey, and prey hunting, by developing a bioeconomic model that is estimated using a dynamic spatial-lag model (dynamic SAR). The results show that a conversion of coniferous and broadleaf forests into grazing land increases game harvests and could offset the negative impact of large carnivores on hunting outcomes. Yet, such conversion is likely to be associated with a net social cost. In contrast, there are both increased game harvests and net economic gains from conversion of coniferous forests into broadleaves. Our findings are informative for policymaking on land use and wildlife management.
Trap cropping is a pest management strategy where a grower plants an attractive "trap crop" alongside the primary crop to divert pests away from it. We propose a simple framework for optimizing the proportion of a grower's field or greenhouse allocated to a main crop and a trap crop to maximize agricultural yield. We implement this framework using a model of pest movement governed by trap crop attractiveness, the potential yield threatened by pests, and functional relationships between yield loss and pest density drawn from the literature. Focusing on a simple case, we consider highly mobile pests that move freely across a small field or greenhouse, or within a larger field arranged in a repetitive layout (e.g. rows of trap plants). These pests are assumed to choose plants based solely on their relative attractiveness. We find that allocating 5%-20% of the landscape to trap plants is typically required to maximize yield and achieve effective pest control in the absence of pesticides. For highly attractive trap plants, growers can devote less space because they are more effective; less attractive plants are ineffective even in large numbers. Intermediate attractiveness warrants the greatest investment in trap cropping. However, the results are illustrative rather than prescriptive and could be sensitive to ecological and economic factors not included here, such as pest mortality, reproduction, spatial layout of traps, and additional costs associated with trap cropping. Despite these important caveats, the framework offers a transparent and tractable approach for exploring trade-offs in pest management and can be extended to incorporate more complex pest behaviors, crop spatial configurations, and economic considerations.
There are many concepts of sustainability. Robert Solow argued that sustainability would consist of conserving human well-being over the “very long run”, through the interactions of the environment and other stocks in human decisions and activity. To appraise sustainability, he proposed the maximin criterion , the maximal well-being of the least well-off generation looking forward from the present. This essay interprets Solow's elucidation as extended by other economists. It explains the maximin criterion, compares it with some related concepts and then departs from the model's idealism to identify and discuss seven principles that are propitious to sustainability: The seven sisters of sustainability are balance, transacting, inequality, ignorance, unpredictability, productiveness and prudence.
The tank goby (Glossogobius giuris [G. giuris]), a vital indigenous freshwater species in Kaptai Lake, Bangladesh, supports local livelihoods and nutrition but faces escalating fishing pressure due to rising market demand. This study presents the first comprehensive length-based stock assessment of the species by applying a multimodel approach using TropFishR, Length-based Bayesian Biomass (LBB), and Length-Based Spawning Potential Ratio (LB-SPR) on an 8-month length-frequency data set. The LBB analysis estimated an asymptotic length (L-infinity) of 17.5 cm, with a length at first capture (L-c50) of 6.45 cm, significantly below the optimal capture length (L-c_opt = 9.7 cm) and length at maximum biological yield (L-opt = 12.0 cm), confirming high exploitation of juveniles and recruitment overfishing. Biomass indicators revealed a current-to-virgin biomass ratio (B/B-0) of 0.27 and a current-to-maximum sustainable yield biomass ratio (B/B-MSY) of 0.75, classifying the stock as grossly overfished (B/B-0 < 0.5). The fishing-to-natural mortality ratio (F/M = 1.07) exceeded unity, confirming intense fishing pressure. LB-SPR complemented these findings, estimating an L-c50 of 6.12 cm, well below the length at 50% maturity (L-50 = 11.85 cm), and a spawning potential ratio (SPR) of 8% (6%-10%), far below the target (40%) and limit (20%) reference points, signaling severe recruitment overfishing. Sensitivity analyses across +/- 5% parameter variations demonstrated the robustness of both models. These results underscore the urgent need for management actions, including enhanced gear selectivity (e.g., larger mesh sizes) and minimum size limits (9-10 cm), to protect immature fish and restore G. giuris stock sustainability in Kaptai Lake.
Faced with global resource constraints and environmental challenges, enhancing natural resources utilization efficiency (NRUE) has become a crucial global strategy. The swift advancement of digital economy (DE) offers a new opportunity to tackle these resource and environmental issues. Based on panel data from 47 countries along the Belt and Road Initiative (BRI) from 2013 to 2021, this paper explores the impact of DE on NRUE and its underlying mechanism. The results show that DE has a significant U-shaped nonlinear impact on NRUE, and this finding remains valid after various robustness tests. Additionally, mechanism analysis reveals that DE can exert a nonlinear impact on NRUE by fostering technological innovation and optimizing energy structure. Furthermore, this nonlinear impact effect exhibits distinct heterogeneous characteristics. Compared to digital technology, the sub-dimensions of DE-digital infrastructure, digital market, and digital governance-exert a more pronounced impact effect. Geographically, the nonlinear effects are particularly strong in Southeast Asia, West Asia/North Africa, and Central and Eastern Europe. Finally, extensive analysis indicates that DE has an inverted U-shaped spillover effect on NRUE of neighboring countries. Therefore, BRI countries should expedite the integration of DE with resource-based sectors to meet sustainable development objectives.
National parks have a great role in ecosystems. They provide many natural benefits for different types of animal species. The research underscores the importance of understanding urbanization's effects on protected areas to inform conservation efforts. To predict land use changes in Bamou National Park, data from the TM, ETM+, and OLI sensors for the years 1986, 1996, 2006, and 2016 were classified using the Random Forest method. After validating the model's accuracy, land use simulations were carried out for the year 2050. Mathematical formulation of the CA-Markov model was developed, including transition probability matrices and cellular automata rules. The CA-Markov model indicated an expected increase in construction and agricultural areas by 2050. A significant reduction in the area of pastures was also observed, which could lead to the disappearance of water resources. The transition probability matrix showed robust calibration with historical data, validated through sensitivity analysis. This study highlights the importance of using predictive models like CA-Markov for better management of urban development and ecosystem conservation. Based on the findings, specific policy recommendations are proposed for protected area management, including zoning regulations, buffer zone establishment, and sustainable urban planning measures. The findings of this research can assist policymakers in making more informed decisions to mitigate the negative impacts of urbanization on the environment.
This study develops a deterministic finite-horizon bioeconomic control model linking forest biomass, biodiversity, cumulative harvesting pressure, and disturbance-motivated expected biodiversity losses. Biodiversity is modeled as a productive state variable that feeds back into biomass growth, while cumulative harvesting pressure records the ecological memory of past extraction. Disturbance risk is introduced through a compound Poisson motivation but enters the solved control systems only through a deterministic expected-loss term, so the analysis should be interpreted as an expected-drift benchmark rather than a full stochastic-control treatment. The model compares three governance regimes: a noncooperative open-loop Nash benchmark with free terminal states, a cooperative regulator with fixed terminal ecological targets, and a cooperative regulator with free terminal states. Numerical solutions show that the noncooperative benchmark generates stronger biomass decline and higher cumulative harvesting pressure because private harvesters do not internalize biodiversity's contribution to future productivity. Cooperative regimes generate more favorable ecological trajectories and objective-value outcomes in the calibrated benchmark, with endpoint design shaping terminal adjustments. Local sensitivity analysis, based on regime-consistent perturbations of the boundary-value problems, indicates that the noncooperative benchmark is more responsive to cumulative-pressure damage and expected disturbance losses, while cooperative regimes display smoother or more endpoint-specific responses. Overall, the results highlight the importance of treating biodiversity as productive ecological capital and of accounting for governance structure and endpoint design in dynamic forest-management models.
The objective of this article is to study the heterogeneous effect of the natural resources, the human capital, economic growth and the CO 2 emissions on the ecological footprint and the bio-capacity in the Maghreb countries. For this purpose, the multiple linear regression models was used to present the country's specific results, which indicated that economic growth increases the ecological footprint and biocapacity in Mauritania and decreases the ecological footprint in Tunisia. In addition, the depletion of natural resources decreases the ecological footprint and increases biocapacity in Tunisia while in Morocco; the human capital reduces it which contributes to the environmental degradation. On the other hand, the population growth in Libya and Morocco increased biocapacity. The results of this study also revealed the presence of the environmental Kuznets curve (EKC) in Tunisia but not in the other Maghreb countries. Therefore, some measures and policies should be taken by the governments.
This study explores existence of hydra effect and sustainable harvesting strategies in three species food chain system with all-purpose Holling type response functions (HT-I, II, III, and IV). The hydra effect (as mentioned in Sieber and Hilker 2012) is superficially ecological paradox which refers to an increase of a species population size in response to an increase in its mortality rate. Assuming the interior equilibrium point of the model exists under certain conditions and its stability, the stock-level variation of species biomass under choosy harvesting efforts of the model is measured in terms of hydra effect, maximum sustainable total yield (MSTY), the bionomic equilibrium point, and optimum level of harvesting. In this food chain model, we verified: prey species harvesting demonstrate hydra effect but not the MSY whenever the intermediate predator response function increases. However, the MSY is conditionally attained for the rest Holling type response functions; a top-predator harvesting produce hydra effect but not MSY for Holling type combinations HT-I-HT-III and HT-II-HT-III; the global MSTY is reached due to combined and integrated harvesting policy for certain preconditions and an optimal stock level maximizes the net revenue whenever an optimal effort is applied. The analytical and qualitative results are also supported and verified by numerical simulations.
Nature tourism based on the observation of sea turtles is a socioeconomic activity that promotes the conservation of endangered species. However, tourism can affect the nesting sites, drastically affecting the ecosystem function. In this study, we propose a socio-ecological model to describe the interplay between tourists and a turtle population with temperature-dependent sex determination and an arribada strategy. In the modeling process, we consider that tourists visiting an arribada nesting beach have different behaviors, depending on the region in which they are distributed. The analysis of the model shows that scenarios of sustainable tourism exist when some conditions over the parameters of the model are satisfied. Using numerical simulations of the solutions of the model, we show different scenarios of coexistence of tourists and turtles. However, when the parameters of the model are varied, the solutions of the model might show scenarios of unsustainable tourism. Finally, we discuss the overall results in terms of sustainable or catastrophic scenarios that can occur in the socio-ecological system.
As human development progresses, the conventional energy systems predominantly reliant on coal and oil have not only facilitated socioeconomic advancement but also imposed substantial ecological pressures on natural ecosystems. The over exploitation and utilization of conventional fossil fuels have exacerbated threats to biodiversity, thereby triggering global environmental issues such as escalated greenhouse gas emissions, deteriorating air quality, and water pollution, which severely disrupt ecological equilibrium. To tackle these challenges, the promotion of a sustainable energy transition has become a worldwide consensus. This study capitalizes on the widespread promotion of clean energy sources such as photovoltaics and wind power to investigate the ramifications of energy transformation on regional human societies and migratory bird systems, employing an analytical framework titled Energy Structure Transformation-Clean Energy Utilization-Habitat Modification. Utilizing Geographic Information System (GIS) tools for data collection and analysis, this study evaluates the comprehensive niche width, relative niche width, and niche overlap of migratory bird habitats within the context of energy use transformation using an ecological niche model. Additionally, this study delves into the driving factors behind the impact of energy use transformation on the biodiversity of migratory bird sanctuaries, unveiling the potential implications of adjusting energy use structure for biodiversity conservation. The research findings consist of two main aspects. First, the implementation of a green energy transformation can effectively contribute to carbon reduction and enhance carbon sinks. Second, the utilization of clean energy has positive ecological implications that can facilitate improvements in migratory bird habitats, thereby supporting their nesting and reproductive activities. Based on these findings, the following policy recommendations are proposed. (1) Expand clean energy production capacity to facilitate carbon reduction initiatives. (2) Strengthen education and outreach programs on clean energy utilization to enhance public comprehension of carbon reduction strategies and promote the establishment of additional carbon sinks. (3) Enhance monitoring mechanisms for green electricity carbon sinks, providing incentives such as subsidies to farmers and consumers to advance biodiversity conservation efforts.
As a consequence of climate change, the encroachment of the native species Empetrum nigrum (crowberry) is exerting multifaceted effects on the Arctic socio-ecological system in Norway. The native invader detrimentally affects the quality of the reindeer grazing land, yet is beneficial for carbon sequestration, that is, providing both ecosystem services and disservices. Though the Norwegian reindeer husbandry acknowledges the importance of pasture quality, the government has not adopted any quantitative indicator to evaluate the current situation. Employing optimal control in a bioeconomic model of three species-reindeer, vegetation, and crowberry-we explore the effectiveness of three controls: slaughter and feeding of reindeer, and burning crowberry, in the short run (5 years) and long run (30 years). Our study seeks to determine the optimal crowberry burning effort and assess whether incorporating carbon sequestration alters the preferred burning strategy. Our results emphasize the critical role of crowberry burning in rejuvenating vegetation, a key indicator of pasture quality, especially in the long run. Burning crowberry remains optimal when carbon sequestration is included, yet at a lower level than when this value is excluded. We also highlight the incorporation of a salvage value for the palatable pasture, advocating for a balanced approach to burning that optimizes economic net benefit while sustaining pasture quality. Incorporating salvage values into the social welfare function emphasizes both the potential future use and the preservation of the grazing pasture for future generations. Our results suggest that the decision-maker should continue burning crowberry in the long run while taking into account the plant's carbon sequestration, to maximize social welfare.
