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Economic efficiency is affected by several traits, and as the unit of selection is the individual, in artificial selection, to promote the maximization of economic genetic gain, the traits to be improved must be weighted by their respective economic values. In Brazil, breeding goals are defined empirically, and not based on an economic evaluation, therefore, the aim of this study was to estimate economic values for traits of economic importance in dairy farming systems based on the use of purebred and crossbred Guzerat animals. The economic values for 305-days milk yield (MY), fat yield (FY), protein yield (PY), and somatic cell count (SCC) were calculated for different production systems based on the feed management: System 1, based on pasture grazing with Brachiaria brizantha or Panicum maximum cv. Mombaça during rainy season, and corn-silage supplementation during the dry season; System 2, based on pasture grazing with Brachiaria brizantha or Panicum maximum cv. Mombaça during rainy season, and the mixture of sugarcane including urea supplementation during the dry season. Bioeconomic models were applied to estimate economic values, and a sensitivity analysis was performed. Four selection indexes were defined, each one with different goals: milk (I1), milk + protein yield (I2), I2 + fat yield (I3) and I3 + somatic cell count (I4). The economic values for MY and PY were positive for both production systems. However, for FY, the values were positive for System 2 but negative for System 1. The economic value for SCC was negative (-7.33 per SCS per lactation). The selection responses for I1 were higher than those for I2, I3 and I4, for both production systems. I4 presented the highest expected genetic gain for each trait, except for fat yield, whose expected genetic gain was greater with the use of I2, in both production systems. The results indicates that the inclusion of milk quality traits in the selection index provides better economic return, and due to the small differences in expected genetic superiority, I1 is still the most suitable for crossbred Guzerat herds whose main activity is milk production in Brazil. [ABSTRACT FROM AUTHOR] more...

Much uncertainty exists about the long-term effect of coral degradation on reef fishery yields. While previous studies have addressed this issue, empirical examinations of the fish-habitat linkage accounting for the stock dynamics are limited. We develop a bioeconomic model that integrates the fish population dynamics with coral reef habitat effects. We test the linkage between fish yield and live coral habitats and simulate the reductions in maximum sustainable yield (MSY) and maximum economic yield (MEY) due to live coral losses with data from the Great Barrier Reef (GBR). Results indicate dependency of fish yield on live coral cover for two GBR commercial fish species, to which substantial yield loss may occur because of live coral damage. Furthermore, results suggest a critical threshold of live coral coverage for these two species, below which maintaining equilibrium MEY becomes challenging. [ABSTRACT FROM AUTHOR] more...

ABSTRACT: Mastitis is one of the most common diseases of dairy cattle. It has a high impact on-farm economy, farmers' working time, and antimicrobial usage (AMU). Selective dry cow therapy (SDCT) is an effective means of reducing AMU without negatively affecting udder health. The objective of our study was to evaluate the impact of SDCT implementation on farmer income, working time, and AMU, using a bioeconomic model. A stochastic dairy simulation model (DairyHealthSim) based on a weekly model was used to simulate herd dynamics, reproduction, milk production, culling decisions, health outcomes, and the management of health events. A specific module was developed for the simulation of quarter-level IMI acquisition and elimination during the lactation and dry-off periods, and 25 different farm settings were defined to represent herds with various udder health situations. We then defined 20 scenarios of SDCT by combining both the use of different thresholds of SCC and milk bacteriology for treatment allocation and the use of internal teat sealant (ITS). All SDCT protocols had little effect on farmer income, and we identified some protocols with a positive farm gross margin (up to Can$15.83/dried cow; at time of writing, Can$1 = US$0.72). We also found that adding an ITS to all cows led to greater economic gain. The application of SDCT had little effect on farmers' working time, except when milk bacteriology was used for decision making. Antimicrobial treatment to all cows above 200,000 cells/mL at last control, with the use of ITS on all cows, seems a good choice in most dairy farms. These findings could be used to convince farmers to adopt this strategy at dry-off. more...

Rationing aquaculture farming feed is challenging for producers due to high feed costs, representing 30%–60% of the total operating costs. Therefore, optimal timing of feeding could lead to improved economic returns from an aquatic system. An optimal dynamic feeding model has been determined considering the von Bertalanffy growth model. A bioeconomic model of tilapia production in Mexico for specific markets was used for numerical illustration. The von Bertalanffy growth model was parameterized with experimental data from tilapia (Oreochromis niloticus) fed four ration sizes (50%, 80%, 100%, and satiety), in order to determine different optimal rationing for different fish sizes (200, 300, and 400 g), market prices (Monterrey, Cancún, Mexico City, and On site), and optimal harvesting times (OHT), considering the time value of money. The results of the modeled optimal feeding trajectories show a continuous decrease from stocking to reach a minimum value and then slightly approaching the harvest size. This result contrasts with the recommendations of the feed suppliers and with those found when a potential growth model was used. The results in the case study showed that the Monterrey market presented the highest present value of the benefits in the OHT and the different market sizes. The implications of the Bertalanffy model for optimal rationing trajectories are presented in the discussion. [ABSTRACT FROM AUTHOR] more...

Warming oceans affect the growth, reproduction and location of fish species. Using a bioeconomic framework, we estimate the relationship between sea surface temperature (SST) and the catch of de facto open‐access commercial fisheries of flatfish, trevally and jack mackerel in New Zealand. Assuming either a logarithmic or quadratic relationship between the SST and the carrying capacity of the fish stock, we consider three fishing methods (bottom trawl, set net and midwater trawl) and two measures of effort (count and duration). We show that ocean warming results in an increase in catch for all species if we assume a logarithmic relationship, with the highest marginal product of SST (MPSST) for jack mackerel caught using midwater trawl. The highest marginal revenue product (computed by the MPSST, current price and fished area) is found for flatfish caught by set net. However, when assuming a quadratic relationship, there is a threshold above which catch starts to decrease, with the maximum catch of species ranging between 10 and 12.2°C. These results also vary spatially, with higher values of MPSST observed in areas closer to the South Pole. Our findings are relevant for any review of fisheries management systems in response to ocean warming. [ABSTRACT FROM AUTHOR] more...

In this paper, we propose a host–parasitoid model with a Holling type-II functional response and incorporate harvest effort. The Holling type-II response leads to saturation in parasitized hosts, creating a potential economic harvesting opportunity. To address overexploitation risks, we integrate a harvest effort function, determining an optimal threshold to prevent depletion. We explore model dynamics and bifurcations, including co-dimension one behaviors such as flip and Neimark–Sacker bifurcations, we provide numerical examples for validation. Our suggested difference-algebraic model, compared to continuous-time models, exhibits rich dynamics within the Nicholson–Bailey host–parasitoid framework. [ABSTRACT FROM AUTHOR] more...

In the single‐species literature, it is widely acknowledged that conserving young fish for future harvesting is beneficial. This finding holds great significance in fisheries economics and has garnered substantial attention over the years. In this study, a full‐blown age‐structured predator–prey model is developed and used to demonstrate that multispecies considerations may shift the optimal selection of predators towards smaller individuals, providing valuable counteractive insights. These new results offer a fresh perspective highly relevant to regulation and choice of selectivity patterns. Recommendations for Resource Managers: Single‐species analyses often suggest that it is optimal to design gear restrictions to spare young fish for future harvest. However, this study reveals that the dynamics of predator–prey interactions may challenge this notion. Specifically, our findings demonstrate that targeting only large predators can result in disadvantages, including increased prey mortality, decreased utilization of growth potential, and lower catch per unit effort for the prey. As a result, managers should exercise caution when contemplating changes in gear restrictions for predator species that are integral to a predator–prey system involving high‐value prey. [ABSTRACT FROM AUTHOR] more...

This study presents a bioeconomic model of prey-predator interactions incorporating the presence of refuges for prey species to mitigate predation. The main objective is to assess the impact of prey refuges on prey biomass, predator biomass, catches, fishing effort, and profits for fishermen exploiting these marine species. The model analyzes system positivity and boundedness, examines equilibrium points and their stability, and conducts numerical simulations by varying the refuge availability parameter (m) to interpret the effects on fishing effort, catches, and profits across different scenarios. The findings shed light on the dynamics of the ecosystem and highlight the importance of refuge availability in sustainable fisheries management, supporting the conservation of marine resources and the well-being of fishermen. [ABSTRACT FROM AUTHOR] more...

Indoor agriculture is an innovative and environmentally sustainable approach to high-quality food production, utilizing advanced technology to reduce water usage by 95% and achieve a 100-fold increase in production per unit of land compared to conventional farming systems. These enclosed systems provide year-round production of pesticide-free fresh food, even in cities with less favourable climates, addressing food deserts and creating employment opportunities in urban areas. However, the industry faces significant challenges, primarily stemming from substantial investment and operating costs, exacerbated by a limited understanding of the input-output relationship within these systems. This study employs a bioeconomic framework to establish a foundational production function based on growth cycle duration (time) and required growing area (space). Through a partial budget analysis, a 19-day production schedule was identified to provide the highest contribution margin to profits. Results set the minimum size of this hypothetical lettuce indoor farm at 273 m2, rendering it suitable for installation in urban areas. The farm harvests 118 kg per day, within an 800 m2 growing area distributed across four vertically stacked shelves. Estimates of economic output sensitivity to exogenous factors in the US context are also presented, along with a comparison between cost-minimizing and revenue-maximizing strategies. [ABSTRACT FROM AUTHOR] more...

Plant disease control is often implemented at the private property level, and problems of cooperation and coordination between landowners can lead to social inefficiencies. Drawing on the private management problem of sharka on Prunus trees, we analyse an epidemic game and its outcomes according to initial infection levels. We show that, depending on the infection level in each farm, the nature of strategic interactions changes drastically, and a wide range of games can occur, including games with multiple or without pure strategy equilibria and games with coordination or anti-coordination patterns. We characterise the epidemic conditions for which private management produces social inefficiency and analyse the properties of uniform and differentiated subsidy schemes to solve it. We conclude with a discussion of the policy implications of the ongoing deregulation of sharka management in France. [ABSTRACT FROM AUTHOR] more...

This study evaluated the effects of antral follicle count (AFC) in female cattle on offspring characteristics. Recently calved multiparous Bos indicus cows (Nelore; n = 222) were evaluated using ultrasonography on random days of their estrous cycle to determine the AFC and were classified into "low" (≤15 follicles), "intermediate" (≥16 and ≤ 29 follicles), and "high" (≥30 follicles) AFC groups. Weight and scrotal circumference (SC) of male offspring from these cows (n = 127) were determined from 20 to 27 months, and the data were added to a genetic evaluation program (economic total genetic merit, MGTe and TOP value) that uses the kinship matrix to evaluate the genetic relationship between animals. The AFC of female offspring from these cows (n = 95) was evaluated to analyze the relationship between the AFC of mothers and daughters. The effects of maternal AFC on the genetic merit of male and female offspring were analyzed using GLIMMIX and GLM, respectively. Correlations were assessed using the Pearson's coefficient. Male offspring of cows with high AFC had superior MGTe (P = 0.005) and TOP values (P = 0.01) than those from cows with low AFC. Additionally, the AFC of mothers was positively correlated with MGTe (R = 0.33; P < 0.0001) and negatively correlated with TOP values (R = −0.32; P < 0.0001). The SC (P = 0.01), but not body weight of the offspring (P = 0.46) was affected by maternal AFC. The daughters' AFC were correlated (R = 0.29; P = 0.004) with mothers' AFC and were influenced by maternal (P = 0.05) but not paternal (P = 0.77) effect. In conclusion, cows with high AFC produced males with greater MGTe, superior TOP values and higher SC. Maternal AFC did not influence the weight of male offspring but was correlated with the AFC of daughters. • Cows with high AFC had male offspring with higher economic total genetic merit. • Cow with high AFC also had male offspring with superior TOP index. • Maternal AFC influence the scrotal circumference but did not offspring weight. • The number of antral follicles of daughters was affected by maternal AFC. • Maternal AFC was correlated with the AFC of their daughters. [ABSTRACT FROM AUTHOR] more...

This work seeks to demonstrate how light pollution impacts fishing activities, including catch rates and the profits of fishermen. Our goal is to examine how light pollution affects the fishing dynamics of sardines and anchovies in the Casablanca-Rabat region of Morocco, within a bioeconomic framework involving these two marine populations. In this article, we show that our model is well posed by studying the positivity and the boundedness of our system, and then we show the local stability of the interior equilibrium point. Then, we move on to calculating the fishing effort that maximizes fishermen’s profits and catches under two main constraints: The influence of light pollution on the sustained viability of the sardine and anchovy populations. Using data reported by the National Fisheries Research Institute (INRH), we obtain detailed results in numerical simulations. [ABSTRACT FROM AUTHOR] more...

BACKGROUND: Drosophila suzukii is a significant invasive pest that has caused high management costs and economic losses for blueberry growers in the United States. The status quo control strategy commonly used by growers is to apply pesticides proactively and frequently to reduce infestation. Recent studies have shown that the calendar‐based spraying strategy might be unsustainable in the long term, making the reduction of pesticide reliance a top priority for the berry industry. Incorporating pest monitoring into the control strategy could be an option to improve efficiency while reducing pesticide usage. This study assesses the economic implications of monitoring‐based control strategies compared to calendar‐based spraying control strategies for organic blueberry production in Oregon. We combine a D. suzukii population model into the economic simulation framework, evaluate two monitoring methods (adult trapping and fruit sampling), and identify the profit‐maximizing control strategy under different scenarios. RESULTS: In the baseline scenario, control strategies that incorporate fruit sampling exhibit the highest average profits. Although the status quo control strategy (spraying every 3 days) generates higher average revenue than monitoring‐based strategies, the cost from the higher number of pesticide application offsets the returns. CONCLUSION: This study uses a novel bioeconomic simulation framework to show that incorporating fruit sampling can be a promising tool to reduce pesticide reliance while controlling D. suzukii infestation. These findings provide clearer information on the economic viability of using monitoring‐based pest control strategies in organic berry production, and the assessment framework sheds light on the economics of pest management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR] more...

Phalaris brachystachys (short-spiked canary grass) is considered to be among the most troublesome cereal weeds in Mediterranean areas. A bioeconomic model, based on population dynamics, competition and economic sub-models, was developed to simulate the long-term economic consequence of using herbicide-based strategies: no herbicide application, full herbicide dose (standard rate) and two reduced dose rates (75 and 50% of the standard rate) to control P. brachystachys in a biennial wheat–sunflower rotation. Simulation results indicated that only herbicide application at a full dose (90% control) and 3/4 dose (80% control) produced positive economic results, with the full dose being the best strategy (EUR 98.65 ha−1 year−1). A sensitivity analysis showed that the economic outcome, in terms of annualized net return, was strongly influenced by changes in yield, price, and fixed costs. In addition, the annualized net return was more sensitive to parameter changes at reduced herbicide doses than at full rate. In the wheat–sunflower rotation system, the application of the full dose of herbicide was the most economical and stable strategy in the long-term. Reduced doses are not a recommended option from an economic point of view. Bioeconomic models provide practical insight into different management approaches for effective weed control. [ABSTRACT FROM AUTHOR] more...

The primary aim of this research is to investigate how the presence of toxicity, stemming from phytoplankton, impacts fishing activities, catch levels, and financial returns. It is hypothesized that this toxicity arises when zooplankton accumulates harmful substances while consuming phytoplankton. To achieve this objective, we analyze a model resembling a prey-predator relationship involving phytoplankton. We examine the stable conditions in our model by utilizing eigenvalue analysis and calculate the optimal fishing effort that maximizes profitability for fishermen, employing the concept of generalized Nash equilibrium. Additionally, we explore the most effective harvesting strategy by applying Pontryagin's maximum principle. In our numerical simulations, we identify the key variables that influence all economic aspects of the model, including fishing effort, catch levels, and benefits. Furthermore, we compare our results with findings from previous research. [ABSTRACT FROM AUTHOR] more...

Baalbeck El Hermel Governorate, particularly the semi-arid region is increasingly threatened by climate change. These disturbances, more specifically, concerning the limit in water resources generate problems for the agricultural systems constituting the principle source of families’ subsistence in this zone. This study was established to evaluate, via a bioeconomic modeling approach, the resilience of agricultural systems in Baalbeck El Hermel and perceive their adaptation techniques under conditions of water scarcity. In this context, we have selected three typical farms representative of the driest northern zone receiving the least precipitation. Several behaviors and levels of resilience of these farms were showed after analysis of the results: 1) farms specializing in market gardening or perennial crops are very sensitive to drought conditions and are not resilient in the face of water limit conditions; 2) the diversified farm with olive tree dominance is less sensitive and more resilient. The analysis of the water pricing scenario showed an improvement in water management but a limit in the adaptive capacity of farmers, hence the necessity to adapt resilience-building strategies for the targeted zone. [ABSTRACT FROM AUTHOR] more...

In this study, we delve into the complex interplay between the Allee effect and a tri-trophic marine ecosystem of zooplankton, sardines, and sharks in Moroccan waters, aiming to contribute to the field of coastal conservation, planning, and management. Our investigation focuses on understanding the impact of the Allee effect on catches, profits, and fishing efforts within the context of bioeconomic models. By analyzing the positive aspects, boundaries, and equilibrium points, we examine how the Allee effect influences the fishing efforts and overall performance of fishermen, providing valuable insights for sustainable fishing practices. The research outcomes shed light on the intricate interplay among the Allee effect, economic variables, and the abundance of diverse species, thereby offering crucial guidance for effective coastal conservation, planning, and management strategies. [ABSTRACT FROM AUTHOR] more...

The regeneration system of Borassus aethiopum in Burkina Faso is the subject of several hypotheses. However, it is challenging to implement appropriate conservation strategies due to the lack of usage of bioeconomic approaches to support this or that perspective. The objective of this study is to settle this debate by assessing the status of palm tree stands using a bioeconomic model based on a dynamic equilibrium price. The data used in the study was gathered from thirty farming households in the study area in 2010, 2015, and 2020, as well as from monitoring thirty farm sites. The results show that, on average, there is an equilibrium between the rate of harvesting and the rate of regeneration of the palmyra palm. Nonetheless, market prices do not reflect the species' value, as they are between 28% and 166% below their implicit level. To ensure a proportionality coefficient between the equilibrium price and the resource constraint, a dynamic Pigouvian tax should be applied, taking into account the gap, the rate of exploitation, and regeneration. [ABSTRACT FROM AUTHOR] more...

Sustainable development (SD) policies targeting marine economic sectors, designed to alleviate poverty and conserve marine ecosystems, have proliferated in recent years. Many developing countries are providing poor fishing households with new fishing boats (fishing capital) that can be used further offshore as a means to improve incomes and relieve fishing pressure on nearshore fish stocks. These kinds of policies are a marine variant of traditional SD policies focused on agriculture. Here, we evaluate ex ante economic and environmental impacts of provisions of fishing and agricultural capital, with and without enforcement of fishing regulations that prohibit the use of larger vessels in nearshore habitats. Combining methods from development economics, natural resource economics, and marine ecology, we use a unique dataset and modeling framework to account for linkages between households, business sectors, markets, and local fish stocks. We show that the policies investing capital in local marine fisheries or agricultural sectors achieve income gains for targeted households, but knock-on effects lead to increased harvest of nearshore fish, making them unlikely to achieve conservation objectives in rural coastal economies. However, pairing an agriculture stimulus with increasing enforcement of existing fisheries' regulations may lead to a win-win situation. While marine-based policies could be an important tool to achieve two of the United Nations Sustainable Development Goals (alleviate poverty and protect vulnerable marine resources), their success is by no means assured and requires consideration of land and marine socioeconomic linkages inherent in rural economies. more...

ABSTRACT: Foot disorders are costly health disorders in dairy farms, and their prevalence is related to several factors such as breed, nutrition, and farmer's management strategy. Very few modeling approaches have considered the dynamics of foot disorders and their interaction with farm management strategies within a holistic farm simulation model. The aim of this study was to estimate the cost of foot disorders in dairy herds by simulating strategies for managing lameness. A dynamic and stochastic simulation model (DairyHealthSim) was used to simulate the herd dynamics, reproduction management, and health events. A specific module was built for lameness and related herd-level management strategies. Foot disorder occurrences were simulated with a base risk for each etiology [digital dermatitis (DD), interdigital dermatitis, interdigital phlegmon, sole ulcer (SU), white line disease (WLD)]. Two state machines were implemented in the model: the first was related to the disease-induced lameness score (from 1 to 5), and the second concerned DD-state transitions. A total of 880 simulations were run to represent the combination of the following 5 scenarios: (1) housing (concrete vs. textured), (2) hygiene (2 different scraping frequencies), (3) the existence of preventive trimming, (4) different thresholds of DD prevalence detected and from which a collective footbath is applied to treat DD, and (5) farmer's ability to detect lameness (detection rate). Housing, hygiene, and trimming scenarios were associated with risk factors applied for each foot disorder etiologies. The footbath and lameness detection scenarios both determined the treatment setup and the policy of herd observance. The economic evaluation outcome was the gross margin per year. A linear regression model was run to estimate the cost per lame cow (lameness score ≥3), per case of DD and per week of a cow's medium lameness duration. The bioeconomic model reproduced a lameness prevalence varying from 26 to 98% depending on the management scenario, demonstrating a high capacity of the model to represent the diversity of the field situations. Digital dermatitis represented half of the total lameness cases, followed by interdigital dermatitis (28%), SU (19%), WLD (13%), and interdigital phlegmon (4%). The housing scenarios dramatically influenced the prevalence of SU and WLD, whereas scraping frequency and threshold for footbath application mainly determined the presence of DD. Interestingly, the results showed that preventive trimming allowed a better reduction in lameness prevalence than spending time on early detection. Scraping frequency was highly associated with DD occurrence, especially with a textured floor. The regression showed that costs were homogeneous (i.e., did not change with lameness prevalence; marginal cost equals average cost). A lame cow and a DD-affected cow cost €307.50 ± 8.40 (SD) and €391.80 ± 10.0 per year on average, respectively. The results also showed a cost of €12.10 ± 0.36 per week-cow lameness. The present estimation is the first to account for interactions between etiologies and for the complex DD dynamics with all the M-stage transitions, bringing a high level of accuracy to the results. more...

Technical interactions (multiple fleets fishing multiple species with various gears, as either target or bycatch), bycatch regulations through a landing obligation, and biological and economic effects of climate change, affecting fisheries yield and profits, provide a challenge for demersal mixed fisheries of the North Sea. A multi‐stock, multi‐fleet, bioeconomic model was used to understand management options under these combined influences. Scenarios considered climate change effects on recruitment of three main gadoid stocks (cod – Gadus morhua, saithe – Pollachius virens, whiting – Merlangius merlangus), possible future developments of fuel and fish prices, and strict implementation of a landing obligation. The latter leads to decreased yield and profits in the short term due to increased choke effects, mainly of North Sea cod, being influenced by climate‐induced productivity changes. Allowing fishing above FMSY, but within sustainable limits, or limiting year‐to‐year quota changes, could help buffer initial losses at the expense of decreased profits in the mid‐ to long‐term. Economic performance of individual fleets was linked to their main target's stock status, cost structure, and fuel and fish prices. The results highlight a need to consider both biological and economic consequences of climate change in the management of mixed fisheries. [ABSTRACT FROM AUTHOR] more...

Standard dynamic resource optimization approaches, such as value function iteration, are challenged by problems involving complex uncertainty and a large state space. We extend a solution technique to address these limitations called approximate dynamic programming (ADP). ADP recently emerged in the macroeco-nomics literature and is novel to bioeconomics. We demonstrate ADP in solving a simple fishery management model under uncertainty to show: the mechanics of ADP in simplest form; the accuracy of ADP; the value of a nonparametric extension; and readily adaptable, non-specialized code. We then demonstrate ADP’s capacity to handle rich bioeconomic problems by solving the fishery management problem subject to four autocorrelated shock processes (governing economic returns and biological dynamics) which entails four sources of stochasticity and five continuous state variables. We find that accounting for multiple autocorrelation has important impacts on harvest policy and generates gains that depend crucially on the structure of harvest cost. more...

Backyard aquaculture is gaining importance as a source of food and economic input for rural families in Mexico. The profitability of this system needs to be determined. Bioeconomic tools allow for making profit projections of any production system. A bioeconomic model composed of biological, production, and economic sub-models was developed to evaluate a low-cost backyard aquaculture system (BAS) appropriate for rural communities, considering theoretical productive parameters at certain environmental conditions. The BAS consisted of a 2800 L water reservoir stocked with 168 masculinized 1 g fingerlings of tilapia (Oreochromis niloticus) at 60 ind m-3 density and aerated with two ventury-type submerged pumps of 0.046 hp at a rate of 1400 L h-1 each. Two culture cycles of 25 weeks each were analysed. The initial investment was USD 1200 (USD 775 equipment + USD 425 operation cost yr-1). Results from the model indicate the production of 303 fishes of 614 g, equivalent to 186 kg yr-1, considering 10% mortality. Selling at USD 3.62 kg-1, net profits varied from USD 184 to 16 at 0 and 25% self-consumption. The payback period was three and four years at 0 and 10% self-consumption but was longer than five years at 25%. A response surface plot of profitability indicators (costbenefit, net present value, and internal rate of return) was constructed at different self-consumption percentages, sale prices, and temperatures. In conclusion, BAS is a viable self-sustainable alternative for tilapia production at a low scale in rural areas of Mexico and other Latin American countries. [ABSTRACT FROM AUTHOR] more...

Taxation policy for fishing received global consent to protect fisheries from drastic harvesting. Still, it should be applied sustainably for a greater ecological and economic benefit because over-taxation may impair fishers' earnings and reduce the overall societal revenue. The fish disease may alter the system dynamics and reduce the revenue generation from the fishery. This paper proposes a nonlinear bioeconomic harvesting model of a single-species fishery with infection, variable market price, and nonlinear demand to explore taxation's ecological and economic effects. We provide the stability results of the system's different ecological and economic equilibrium points. The analytical conditions for the existence of transcritical bifurcation are also established. The computational results show that the system exhibits three dynamical regimes depending on the fishing tax. Taxation might control intensive harvesting but augment disease spreading and price hiking. Higher regulatory tax may even cause a regime shift, where the system enters into a non-harvesting regime from the harvesting one, causing an ecological and economic imbalance. Using Pontryagin's maximum principle, we decipher that some optimal fishing tax exists for the maximum societal benefit in a disease-induced fishery. [ABSTRACT FROM AUTHOR] more...

This research focuses on the economic component of a bioeconomic model for spotted seatrout in the recreational fisheries on Florida's west coast. A survey was designed to assess how anglers, who caught or targeted spotted seatrout on Florida's west coast, valued combined changes in the existing bag limit and size limit. The biological component of the stated preference model deemed such change necessary to ensure a sustainable stock. The biological model provides an economic constraint and results in the treatment of the bag and size limits as a composite good in which separate utilities cannot be measured for each component of the composite good. The stated preference choice method (SPCM) was used to estimate the change in economic value by boat mode of access (e.g., charter boat and private boat). The models also controlled for length of trip (full day versus half-day) for charter boat trips and for type of day (weekend or weekday) for both boat modes of access. Since those who accessed the fishery by private boat had a lower probability of achieving the bag limit/size limit, a model was run to predict the probability of achieving the bag limit/size limit and the probability was interacted with the bag limit/size limit choice. This yielded a positive willingness to pay for the bag limit/size limit combination that was sustainable. Estimated values per person per day for changing the bag limit/size limits to a sustainable level were USD 20.24 for the charter boat mode and USD 32.54 for the private boat mode. Aggregating this to a total value change using a five-year annual average (2012–2016) of total days of fishing for spotted seatrout on Florida's West Coast yielded an estimate of USD 147.9 million per year for charter boat anglers. The total annual value was about USD 3.4 million, while for private boat anglers the annual value was about USD 144.5 million. [ABSTRACT FROM AUTHOR] more...

Consideration of economic outcomes is commonplace in most fisheries management systems globally, although only a few jurisdictions have adopted an economic objective as the primary target for fisheries management. Such an objective has been adopted for Australia's federally managed fisheries, with maximum economic yield (MEY) identified as the primary management objective. Correspondingly, target reference points defined in terms of biomass (i.e., BMEY) are used in harvest control rules. In the absence of explicit BMEY estimates, proxy estimates based on maximum sustainable yield (i.e., BMSY) are used. Identifying BMEY in multi-species fisheries is complicated as most stock assessments are undertaken at the individual species level, but economic activity occurs across species. This is further complicated when different fishing activities using different fishing gears and targeting practices (i.e., métiers) are present in a fishery. We employ an age-structured bioeconomic model to estimate BMEY for key species in a multi-species, multi-métier fishery. We find that optimal biomass levels are substantially higher than those assumed under the current proxy-based system, and that the economic targets are sensitive to prices and fishing costs, both of which change over time. [ABSTRACT FROM AUTHOR] more...

Recycling is emerging as both a viable alternative to extraction in many industries and a cornerstone of the circular economy. In this paper, we assess the role of paper and cardboard recycling on the forest sector, from both an economic and carbon perspective. For this purpose, we add the recycling industry to an existing forest-sector model in an attempt to capture its effects on other wood products and the overall forest resource. As the forest sector has an important potential for climate change mitigation, this model allows us to assess the effects of increased paper and cardboard recycling on the availability of the natural resource and the carbon balance of the forest sector. We show that these results are strongly linked to the hypotheses of substitutability and/or complementarity of recycled pulp and virgin pulpwood. Although we find increased emissions at the pulp sector level, the effects on emissions in other wood products are small. When pulp products are considered substitutes, we find the impact on total net sequestration to be positive. In the case where pulp products are considered complements, we find the impact on total net sequestration to be negative. [ABSTRACT FROM AUTHOR] more...

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. • Homogeneous and heterogeneous variation of initial stocking size in tilapia culture was evaluated. • Sizes of 350, 400, 450 and 500 g were considered as minimum market sizes. • Homogeneous seeding size generated less uncertainty in the model. • In the initial seeding of homogeneous sizes, the strategy of two partial harvest showed a profit 11.29% higher than that of one partial harvest. • In the initial seeding of heterogeneous sizes, the strategy of one partial harvest showed a profit 1.31% higher than that of two partial harvests. [ABSTRACT FROM AUTHOR] more...

Phalaris brachystachys (short-spiked canary grass) is considered to be among the most troublesome cereal weeds in Mediterranean areas. A bioeconomic model, based on population dynamics, competition and economic sub-models, was developed to simulate the long-term economic consequence of using herbicide-based strategies: no herbicide application, full herbicide dose (standard rate) and two reduced dose rates (75 and 50% of the standard rate) to control P. brachystachys in a biennial wheat–sunflower rotation. Simulation results indicated that only herbicide application at a full dose (90% control) and 3/4 dose (80% control) produced positive economic results, with the full dose being the best strategy (EUR 98.65 ha−1 year−1). A sensitivity analysis showed that the economic outcome, in terms of annualized net return, was strongly influenced by changes in yield, price, and fixed costs. In addition, the annualized net return was more sensitive to parameter changes at reduced herbicide doses than at full rate. In the wheat–sunflower rotation system, the application of the full dose of herbicide was the most economical and stable strategy in the long-term. Reduced doses are not a recommended option from an economic point of view. Bioeconomic models provide practical insight into different management approaches for effective weed control. more...

The study of Purple-spotted bigeye resources management especially in Batang waters is still minimal, therefore intensive attention and proper management is needed. The objective of this study is to determine the utilization of Purple-spotted bigeye resources in Batang waters. The research was conducted in March – July 2020. Bioeconomic analysis was carried out using the Gordon-Schaefer formula to analyze the fishery production trends in the form of time series. The result shows that the sustainable yield (EMSY) of Purple-spotted bigeye is 2473.16 tons year-1 with optimum effort (FMSY) 2075 trips year-1. The maximum production at maximum economic yield (EMEY) level is 2225.94 tons year-1 with effort (FMEY) 1366 trips year-1. Open access condition of Purple-spotted bigeye will be achieved when the number of fishing effort (EOA) reaches 2732 units with production (EOA) of 2184.03 tons year-1. The production and fishing effort in actual condition showed that the utilization of Purple-spotted bigeye can still be optimized, but it should be done carefully and wisely without exceeding the optimum catch limit to prevent overfishing. more...

Mixed farming systems are gaining interest both as a risk management strategy and to apply agroecological principles. This study set out to assess the sustainability of mixed systems compared to their specialized counterparts. The Orfee bioeconomic farm model was used to simulate three mixed farms: beef and dairy, beef and sheep, and cash crop and beef, under 1990–2017 prices and policies in France. Several sustainability criteria were computed at two scales (i) aggregated farm level, to assess whether mixed farms with several integrated enterprises performed better than if these enterprises were managed in specialized farms, and (ii) unit of product or labour to assess whether a product was produced more sustainably and a worker obtained higher and more stable income in a mixed farm. We found that mixed farms had less work peaks, lower global warming potentials and nitrogen balances, lower total production costs, higher and more stable net incomes than if their enterprises were managed in two specialized farms. However, profitability and income variability of the mixed farms were not better than the best performing specialized farm. The consumption of concentrate feed decreased in the mixed livestock farms but increased in the beef-crop farm that degraded feed-food competition. more...

Recovering endangered species populations when confronted with the threat of invasive species is an ongoing natural resource management challenge. While eradication of the invasive species is often the optimal economic solution, it may not be a feasible nor desirable management action in other cases. For example, when invasive species are desired in one area, but disperse into areas managed for endangered species, managers may be interested in persistent, but cost-effective means of managing dispersers rather than eradicating the source. In the Colorado River, a nonnative rainbow trout (Oncorhynchus mykiss) sport fishery is desired within Glen Canyon National Recreation Area, however, dispersal downriver into the Grand Canyon National Park is not desired as rainbow trout negatively affect endangered humpback chub (Gila cypha). Here, we developed a bioeconomic model incorporating population abundance goals and cost-effectiveness analyses to approximate the optimal control strategies for invasive rainbow trout conditional on achieving endangered humpback chub adult population abundance goals. Model results indicated that the most cost-effective approach to achieve target adult humpback chub abundance was a high level of rainbow trout control over moderately high rainbow trout population abundance. Adult humpback chub abundance goals were achieved at relatively low rainbow trout abundance and control measures were not cost-effective at relatively high rainbow trout abundance. Our model considered population level dynamics, species interaction and economic costs in a multi-objective decision framework to provide a preferred solution to long-run management of invasive and native species. more...

Recovering endangered species populations when confronted with the threat of invasive species is an ongoing natural resource management challenge. While eradication of the invasive species is often the optimal economic solution, it may not be a feasible nor desirable management action in other cases. For example, when invasive species are desired in one area, but disperse into areas managed for endangered species, managers may be interested in persistent, but cost-effective means of managing dispersers rather than eradicating the source. In the Colorado River, a nonnative rainbow trout (Oncorhynchus mykiss) sport fishery is desired within Glen Canyon National Recreation Area, however, dispersal downriver into the Grand Canyon National Park is not desired as rainbow trout negatively affect endangered humpback chub (Gila cypha). Here, we developed a bioeconomic model incorporating population abundance goals and cost-effectiveness analyses to approximate the optimal control strategies for invasive rainbow trout conditional on achieving endangered humpback chub adult population abundance goals. Model results indicated that the most cost-effective approach to achieve target adult humpback chub abundance was a high level of rainbow trout control over moderately high rainbow trout population abundance. Adult humpback chub abundance goals were achieved at relatively low rainbow trout abundance and control measures were not cost-effective at relatively high rainbow trout abundance. Our model considered population level dynamics, species interaction and economic costs in a multi-objective decision framework to provide a preferred solution to long-run management of invasive and native species. more...

In this paper, we propose a host‐parasitoid model with harvest effort. The existence and stability of a positive fixed point are analyzed. The period‐doubling and Neimark–Sacker bifurcations are studied. These analyses are achieved by applying the normal form of the difference‐algebraic system, bifurcation theory, and center manifold theorem. Furthermore, we apply a state‐delayed feedback control strategy to control the complex dynamics of the proposed model. Numerical examples and simulations are given to verify our findings. Owing to the framework of Nicholson–Bailey host‐parasitoid system, the proposed difference‐algebraic model shows rich dynamics compared with the continuous‐time models. [ABSTRACT FROM AUTHOR] more...

The species extinction is caused sometimes by environmental forces such as habitat fragmentation, climate change, natural disaster, evolutionary changes etc, and sometimes by over-exploitation by humans, and pollution, to preserve the biodiversity in order to protect the ecosystem and the environmental life cycle, it is essential to predict the probabilities of the future in the way to interfere to save and protect the species from potential extinction. As the temperature factor is an important element for marine species, in this paper, we aim to estimate the temperature factor by discrete time Markov Chain, and then estimate the profit of two fishermen exploiting three species with some numerical simulations at the end. [ABSTRACT FROM AUTHOR] more...

Organic matter is a key element of soil fertility. However, in-soil stocks of organic matter are in decline in specialized crop farms. Reintroducing organic fertilizers could be a way to increase or at least maintain organic matter stocks in these soils. Straw/manure exchanges between crop farms and livestock farms could improve overall land fertility and thus the long-term income of farmers. Here we used a bioeconomic model to estimate the agronomic and economic benefits of straw/manure exchanges as part of a strategy to improve soil fertility. Iterative simulations were run with prices of farmyard manure varying from €0 to €20 ton-1 to identify the price at which a crop farm can buy manure and sell straw without degrading its net income (manure ceiling price) compared to purchasing mineral fertilizer only and ploughing back straw. Parallel simulations were run to identify the price at which a livestock farmer can sell manure and buy straw without degrading its net income (manure floor price) compared to keeping all manure on the farm and buying straw on the market. The key new contributions of this study are that it (i) considers the characteristics of manure beyond its shortterm fertilizing value, i.e., better mineralization of humus and a 10% increase in crop yields, (ii) estimates both the economic and agronomic benefits of manure and (iii) assesses the impacts of uncertainties on manure effects and prices. The results show that it is profitable for a French farmer in a conventional field crop system to buy manure at a price between €10 ton-1 in the short term and €18 ton-1 in the long term. The results also show that it is still economically advantageous for a livestock farmer to sell part of their manure, even at a very low price. This study shows that it is possible to better distribute manure resources over a territory in a way that enriches the soils of crop farms without degrading the soils of livestock farms. [ABSTRACT FROM AUTHOR] more...

We develop a novel spatial-dynamic model of landowners managing a disease in a perennial crop. We use the model to investigate the dynamic gains from cooperation to address the spatial externality resulting from disease vector dispersal. We find that solving for the complete time path of control decisions is important; cooperation leads to each landowner investing more in treatment in early years than in cases where one agent free rides on the other's control. Our model is based on Pierce's Disease of grapevines in California's Napa Valley but is applicable to a range of diseases in perennial crops. more...

The study aims at reconciling contrasting productive and environmental goals of agricultural policies at a given budget in the context of climate change. Based on a quantitative bioeconomic model integrating interdependencies between agricultural systems and agroecosystems, we compare the impacts of 4 contrasted public policy scenarios based either on productive (food or energy) or environmental goals (pollution reduction or ecosystem state) on a set of 18 bioeconomic indicators. We run the policy scenarios under two contrasted climate change scenarios to investigate their robustness. We confirm that it is possible to achieve productive and environmental goals with the on-going budget of European agricultural policy. Synergies between productive and environmental performances exist even if they are not trivial nor systematic. More precisely, an agricultural public policy which focuses on energy production might offer a good compromise regarding the different facets of agricultural landscapes. The Pollution scenario constitutes a credible environmentally oriented alternative even if it remains slightly less competitive regarding both ecological and economic sides than an energy-oriented policy. Eventually, our analysis shows that our conclusions are robust to climate change, suggesting that adequate agricultural public policies might attenuate climate change effects when considering intermediary climate change scenarios. more...

In the context of increasing global environmental challenges associated with anthropogenic destructive impact on the environment, the bioeconomic direction of sustainable development in combination with a closed production cycle becomes relevant, the development of which would help to overcome the imbalance of the ecological and economic system and minimise the burden on the environment. Therefore, the purpose of this study is to comprehensively consider the prerequisites for the establishment of a framework of categories for combining green concepts of sustainable development, in particular, to substantiate the theoretical and methodological foundations for interpreting the fundamental features of circular bioeconomy to form a specific vision of the issue. The methodological basis of the study is general scientific and special theoretical and empirical methods, in particular inductive and deductive, heuristic method, graphic, analysis and synthesis, etc. At the empirical level, descriptive, comparative, and observational approaches are used. The theoretical level covers the historical, abstract-logical, hypothetical, formalisation method as a manifestation of logical thinking and theoretical generalisation for formulating the results of the study. This study systematises the ideas of leading scientists on the positioning of circular economy and bioeconomy, highlights similarities and differences in the process of combining concepts, identifies fundamental generic and specific features, establishes complementary relationships to generate the author's position and formulate a fundamental vision of the problems of circular bioeconomy. The practical significance of the study is conditioned by scientific substantiation of the terminological platform of the problems of circular bioeconomy. Further research is aimed at developing criteria for regulating the bioeconomic system with subsequent evaluation of results more...

Data from 4,713 fisheries worldwide, representing 78% of global reported fish catch, are analyzed to estimate the status, trends, and benefits of alternative approaches to recovering depleted fisheries. For each fishery, we estimate current biological status and forecast the impacts of contrasting management regimes on catch, profit, and biomass of fish in the sea. We estimate unique recovery targets and trajectories for each fishery, calculate the year-by-year effects of alternative recovery approaches, and model how alternative institutional reforms affect recovery outcomes. Current status is highly heterogeneous-the median fishery is in poor health (overfished, with further overfishing occurring), although 32% of fisheries are in good biological, although not necessarily economic, condition. Our business-as-usual scenario projects further divergence and continued collapse for many of the world's fisheries. Applying sound management reforms to global fisheries in our dataset could generate annual increases exceeding 16 million metric tons (MMT) in catch, $53 billion in profit, and 619 MMT in biomass relative to business as usual. We also find that, with appropriate reforms, recovery can happen quickly, with the median fishery taking under 10 y to reach recovery targets. Our results show that commonsense reforms to fishery management would dramatically improve overall fish abundance while increasing food security and profits. more...

The ocean's mesopelagic zone (200–1000 m) remains one of the most understudied parts of the ocean despite knowledge that mesopelagic fishes are highly abundant. Apex predators from the surface waters are known to consume these fishes, constituting an important ecological interaction. Some countries have begun exploring the potential harvest of mesopelagic fishes to supply fishmeal and fish oil markets due to the high fish abundance in the mesopelagic zone compared with overfished surface waters. This study explored the economic and ecological implications of a moratorium on the harvest of mesopelagic fishes such as lanternfish off the US West Coast, one of the few areas where such resources are managed. We adapted a bioeconomic decision model to examine the tradeoffs between the values gained from a hypothetical mesopelagic fishery with the potential values lost from declines in predators of mesopelagic fishes facing a reduced prey resource. The economic rationale for a moratorium on harvesting mesopelagics was sensitive both to ecological relationships and the scale of the nonmarket values attributed to noncommercial predators. Using a California Current‐based ecological simulation model, we found that most modeled predators of mesopelagic fishes increased in biomass even under high mesopelagic harvest rates, but the changes (either increases or decreases) were small, with relatively few predators responding with more than a 10% change in their biomass. While the ecological simulations implied that a commercial mesopelagic fishery might not have large biomass impacts for many species in the California Current system, there is still a need to further explore the various roles of the mesopelagic zone in the ocean. [ABSTRACT FROM AUTHOR] more...

Mixed farming systems are gaining interest both as a risk management strategy and to apply agroecological principles. This study set out to assess the sustainability of mixed systems compared to their specialized counterparts. The Orfee bioeconomic farm model was used to simulate three mixed farms: beef and dairy, beef and sheep, and cash crop and beef, under 1990–2017 prices and policies in France. Several sustainability criteria were computed at two scales (i) aggregated farm level, to assess whether mixed farms with several integrated enterprises performed better than if these enterprises were managed in specialized farms, and (ii) unit of product or labour to assess whether a product was produced more sustainably and a worker obtained higher and more stable income in a mixed farm. We found that mixed farms had less work peaks, lower global warming potentials and nitrogen balances, lower total production costs, higher and more stable net incomes than if their enterprises were managed in two specialized farms. However, profitability and income variability of the mixed farms were not better than the best performing specialized farm. The consumption of concentrate feed decreased in the mixed livestock farms but increased in the beef-crop farm that degraded feed-food competition. [ABSTRACT FROM AUTHOR] more...

This paper develops a bioeconomic model to investigate the effects of wildlife damage compensation programs, and income taxes, on both wildlife population and social welfare. Wildlife damage compensation programs generally compensate local people after wildlife damage occurred. In our model, the compensation program is financed by government tax revenue. We clarify how the production and consumption behaviors of local people change after introducing income taxes for the compensation program. Based on the steady-state analysis and numerical simulation, we conclude that with appropriate taxation policy under certain conditions, a self-financing wildlife damage compensation programs can both increase wildlife population and improve local social welfare, even under the circumstance where compensation programs financed by external resources lower them, which is obtained in the previous studies. [ABSTRACT FROM AUTHOR] more...