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Dairy development provides substantial potential economic opportunities for smallholder farmers in East Africa, but productivity is constrained by the scarcity of quantity and quality feed. Ruminant livestock production is also associated with negative environmental impacts, including greenhouse gas (GHG) emissions, air pollution, high water consumption, land-use change, and loss of biodiversity. Improved livestock feeding and forages have been highlighted as key entry point to sustainable intensification, increasing food security, and decreasing environmental trade-offs including GHG emission intensities. In this perspective article, we argue that farming systems approaches are essential to understand the multiple roles and impacts of forages in smallholder livelihoods. First, we outline the unique position of forages in crop-livestock systems and systemic obstacles to adoption that call for multidisciplinary thinking. Second, we discuss the importance of matching forage technologies with agroecological and socioeconomic contexts and niches, and systems agronomy that is required. Third, we demonstrate the usefulness of farming systems modeling to estimate multidimensional impacts of forages and for reducing agro-environmental trade-offs. We conclude that improved forages in East Africa are at a crossroads: if adopted by farmers at scale, they can be a cornerstone of pathways toward sustainable livestock systems in East Africa.

Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery.

Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery.

Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also and emblematic species for recreational fishermen. The aim of this thesis is to simulate the response of the French fishing fleets to introduction of alternative management scenarios for the sea bass fishery. Simulation results emphasize the diversity of anticipated impacts of alternative management scenarios from both a short-term and a long-term perspective, and the associated heterogeneity of economic incentives for different fleets to support these management scenarios., Quatrième espèce débarquée en France en valeur, le bar commun (Dicentrarchus labrax) est une ressource importante pour les navires de pêche français. De forte valeur marchande, cette espèce est capturée par une grande diversité de métiers de pêche, induisant des interactions entre de nombreuses flottilles, dont les contributions aux prélèvements et le niveau de dépendance économique à l’espèce sont variables. L’espèce est également emblématique pour la pêche récréative en mer. L’objet de la thèse est d’analyser la pêcherie de bar commun en France, en s’appuyant sur le développement d’un modèle de simulation bioéconomique de cette pêcherie, et en simulant ses réponses possibles à des mesures de conservation. L’analyse est centrée sur la mise en évidence de la diversité des effets à attendre sur les exploitants, à court terme et à long terme, de mesures telles qu’une augmentation de la taille minimale de capture.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also and emblematic species for recreational fishermen. The aim of this thesis is to simulate the response of the French fishing fleets to introduction of alternative management scenarios for the sea bass fishery. Simulation results emphasize the diversity of anticipated impacts of alternative management scenarios from both a short-term and a long-term perspective, and the associated heterogeneity of economic incentives for different fleets to support these management scenarios., Quatrième espèce débarquée en France en valeur, le bar commun (Dicentrarchus labrax) est une ressource importante pour les navires de pêche français. De forte valeur marchande, cette espèce est capturée par une grande diversité de métiers de pêche, induisant des interactions entre de nombreuses flottilles, dont les contributions aux prélèvements et le niveau de dépendance économique à l’espèce sont variables. L’espèce est également emblématique pour la pêche récréative en mer. L’objet de la thèse est d’analyser la pêcherie de bar commun en France, en s’appuyant sur le développement d’un modèle de simulation bioéconomique de cette pêcherie, et en simulant ses réponses possibles à des mesures de conservation. L’analyse est centrée sur la mise en évidence de la diversité des effets à attendre sur les exploitants, à court terme et à long terme, de mesures telles qu’une augmentation de la taille minimale de capture.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also and emblematic species for recreational fishermen. The aim of this thesis is to simulate the response of the French fishing fleets to introduction of alternative management scenarios for the sea bass fishery. Simulation results emphasize the diversity of anticipated impacts of alternative management scenarios from both a short-term and a long-term perspective, and the associated heterogeneity of economic incentives for different fleets to support these management scenarios., Quatrième espèce débarquée en France en valeur, le bar commun (Dicentrarchus labrax) est une ressource importante pour les navires de pêche français. De forte valeur marchande, cette espèce est capturée par une grande diversité de métiers de pêche, induisant des interactions entre de nombreuses flottilles, dont les contributions aux prélèvements et le niveau de dépendance économique à l’espèce sont variables. L’espèce est également emblématique pour la pêche récréative en mer. L’objet de la thèse est d’analyser la pêcherie de bar commun en France, en s’appuyant sur le développement d’un modèle de simulation bioéconomique de cette pêcherie, et en simulant ses réponses possibles à des mesures de conservation. L’analyse est centrée sur la mise en évidence de la diversité des effets à attendre sur les exploitants, à court terme et à long terme, de mesures telles qu’une augmentation de la taille minimale de capture.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also and emblematic species for recreational fishermen. The aim of this thesis is to simulate the response of the French fishing fleets to introduction of alternative management scenarios for the sea bass fishery. Simulation results emphasize the diversity of anticipated impacts of alternative management scenarios from both a short-term and a long-term perspective, and the associated heterogeneity of economic incentives for different fleets to support these management scenarios., Quatrième espèce débarquée en France en valeur, le bar commun (Dicentrarchus labrax) est une ressource importante pour les navires de pêche français. De forte valeur marchande, cette espèce est capturée par une grande diversité de métiers de pêche, induisant des interactions entre de nombreuses flottilles, dont les contributions aux prélèvements et le niveau de dépendance économique à l’espèce sont variables. L’espèce est également emblématique pour la pêche récréative en mer. L’objet de la thèse est d’analyser la pêcherie de bar commun en France, en s’appuyant sur le développement d’un modèle de simulation bioéconomique de cette pêcherie, et en simulant ses réponses possibles à des mesures de conservation. L’analyse est centrée sur la mise en évidence de la diversité des effets à attendre sur les exploitants, à court terme et à long terme, de mesures telles qu’une augmentation de la taille minimale de capture.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms, with approximately 5 500 tons landed, and a total turnover of about 52 million euro in 2006. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also an emblematic species for recreational fishermen. Currently, there is no limitation on total allowable catch in this fishery, nor are catch allocations specified at the individual vessel level. The fishery thus faces the traditional difficulties of common-pool resource management, with a potential for the development of excess capacity and a risk of overexploitation. The nature and strength of externalities between fishing agents can thus be very different according to the fleets considered, and may lead to variable levels of potential support towards management decisions aimed at tackling these externalities. The aim of this paper is to simulate the response of French fishing fleets to the introduction of alternative management scenarios for the sea bass (Dicentrarchus labrax) fishery. The analysis is based on a bioeconomic model which includes and age-structured model of population dynamics and a detailed representation of the numerous fishing fleets which impact the stock, including the size distribution of catches per fleet and per fishing technique, and the economic status of fishing vessels. The main emphasis of the analysis is on the heterogeneity of commercial fleets in terms of both their harvesting capacity and their reliance on sea bass for their revenue; recreational fishing is also included in the analysis and adds to the heterogeneity of behaviors which are accounted for in the model. Simulation results emphasize the diversity of anti

Sustainable management of natural resources, and in particular fisheries, must take into account several conflicting objectives. This is the case in the French Guiana shrimp fishery for which profitability objectives imply a reduction in the fishing activity. On the one hand, this fishery has negative externalities on marine biodiversity due to discards. On the other hand, this fishery has positive externalities on the economy of the local community and interestingly enough on a protected seabird species in the area (the Frigatebird that feeds on discards). In this paper, we examine the viability of that system considering two sustainability objectives: an economic objective in terms of the profitability of the fishing activity, and a conservation objective in terms of the Frigatebird population. For that purpose, we have developed a dynamic model of that bioeconomic system and study here the trade-offs between the two conflicting objectives. It provides a means to quantify the necessary give and takes involving the economic and ecological objectives that would ensure a viable management solution. Our study confirms the relevance of the viability approach to address natural resource management issues, which should lead to the development of new tools for the arbitration of conflicting sustainability, objectives. In particular, such tools could be used as a quantitative basis for cost-benefit analysis taking into account environmental externalities. (C) 2009 Elsevier B.V. All rights reserved.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms, with approximately 5 500 tons landed, and a total turnover of about 52 million euro in 2006. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also an emblematic species for recreational fishermen. Currently, there is no limitation on total allowable catch in this fishery, nor are catch allocations specified at the individual vessel level. The fishery thus faces the traditional difficulties of common-pool resource management, with a potential for the development of excess capacity and a risk of overexploitation. The nature and strength of externalities between fishing agents can thus be very different according to the fleets considered, and may lead to variable levels of potential support towards management decisions aimed at tackling these externalities. The aim of this paper is to simulate the response of French fishing fleets to the introduction of alternative management scenarios for the sea bass (Dicentrarchus labrax) fishery. The analysis is based on a bioeconomic model which includes and age-structured model of population dynamics and a detailed representation of the numerous fishing fleets which impact the stock, including the size distribution of catches per fleet and per fishing technique, and the economic status of fishing vessels. The main emphasis of the analysis is on the heterogeneity of commercial fleets in terms of both their harvesting capacity and their reliance on sea bass for their revenue; recreational fishing is also included in the analysis and adds to the heterogeneity of behaviors which are accounted for in the model. Simulation results emphasize the diversity of anti

Sustainable management of natural resources, and in particular fisheries, must take into account several conflicting objectives. This is the case in the French Guiana shrimp fishery for which profitability objectives imply a reduction in the fishing activity. On the one hand, this fishery has negative externalities on marine biodiversity due to discards. On the other hand, this fishery has positive externalities on the economy of the local community and interestingly enough on a protected seabird species in the area (the Frigatebird that feeds on discards). In this paper, we examine the viability of that system considering two sustainability objectives: an economic objective in terms of the profitability of the fishing activity, and a conservation objective in terms of the Frigatebird population. For that purpose, we have developed a dynamic model of that bioeconomic system and study here the trade-offs between the two conflicting objectives. It provides a means to quantify the necessary give and takes involving the economic and ecological objectives that would ensure a viable management solution. Our study confirms the relevance of the viability approach to address natural resource management issues, which should lead to the development of new tools for the arbitration of conflicting sustainability, objectives. In particular, such tools could be used as a quantitative basis for cost-benefit analysis taking into account environmental externalities. (C) 2009 Elsevier B.V. All rights reserved.

The fishery for common sea bass (Dicentrarchus labrax) is the fourth most important French metropolitan fishery in value terms, with approximately 5 500 tons landed, and a total turnover of about 52 million euro in 2006. Given its high market value, sea bass is targeted by a range of métiers, resulting in interactions between a large number of fleets. The annual contributions to catches and landings of each of these fleets are highly variable, as are their level of economic dependence towards the species. Sea bass is also an emblematic species for recreational fishermen. Currently, there is no limitation on total allowable catch in this fishery, nor are catch allocations specified at the individual vessel level. The fishery thus faces the traditional difficulties of common-pool resource management, with a potential for the development of excess capacity and a risk of overexploitation. The nature and strength of externalities between fishing agents can thus be very different according to the fleets considered, and may lead to variable levels of potential support towards management decisions aimed at tackling these externalities. The aim of this paper is to simulate the response of French fishing fleets to the introduction of alternative management scenarios for the sea bass (Dicentrarchus labrax) fishery. The analysis is based on a bioeconomic model which includes and age-structured model of population dynamics and a detailed representation of the numerous fishing fleets which impact the stock, including the size distribution of catches per fleet and per fishing technique, and the economic status of fishing vessels. The main emphasis of the analysis is on the heterogeneity of commercial fleets in terms of both their harvesting capacity and their reliance on sea bass for their revenue; recreational fishing is also included in the analysis and adds to the heterogeneity of behaviors which are accounted for in the model. Simulation results emphasize the diversity of anti

Sustainable management of natural resources, and in particular fisheries, must take into account several conflicting objectives. This is the case in the French Guiana shrimp fishery for which profitability objectives imply a reduction in the fishing activity. On the one hand, this fishery has negative externalities on marine biodiversity due to discards. On the other hand, this fishery has positive externalities on the economy of the local community and interestingly enough on a protected seabird species in the area (the Frigatebird that feeds on discards). In this paper, we examine the viability of that system considering two sustainability objectives: an economic objective in terms of the profitability of the fishing activity, and a conservation objective in terms of the Frigatebird population. For that purpose, we have developed a dynamic model of that bioeconomic system and study here the trade-offs between the two conflicting objectives. It provides a means to quantify the necessary give and takes involving the economic and ecological objectives that would ensure a viable management solution. Our study confirms the relevance of the viability approach to address natural resource management issues, which should lead to the development of new tools for the arbitration of conflicting sustainability, objectives. In particular, such tools could be used as a quantitative basis for cost-benefit analysis taking into account environmental externalities. (C) 2009 Elsevier B.V. All rights reserved.

Catchability is crucial for the economic performance of fisheries and their management. However, in many bio-economic simulation models it is assumed to be either constant or it is largely ignored, despite the fact that it is known to vary due to technical, environmental and behavioral factors. Such variation can cause the relationship between effort and fishing mortality to be nonlinear. This paper provides evidence for the possibility of nonlinear optimizing behavior from the Dutch beam trawl fishery, provides a methodology for estimating the curvature of the resulting relation, and a simple way of implementing these processes within a bio-economic model. Moreover, it shows the influence of a nonlinear relationship between effort and fishing mortality in a model of effort management (EU long-term flatfish management plan).

RésuméLa Directive cadre sur l’eau impose une stratégie complète pour améliorer l’état écologique et chimique des masses d’eau permettant la mise en place d’une politique spécifique de réduction des pollutions diffuses. Dans le but de comparer différentes mesures agro-environnementales choisies pour contrôler la pollution par les pesticides dans les eaux de surface, les auteurs proposent un cadre méthodologique pour une analyse coût-efficacité distribuée. Ils utilisent le modèle SWAT pour évaluer l’efficacité des mesures appliquées et développent un modèle bioéconomique agrégé pour évaluer les coûts de mise en place et identifier les synergies et substitutions. Cette approche est appliquée sur la partie amont du bassin du Gers dans le Sud-Ouest de la France. Les résultats montrent que le ratio coût-efficacité des mesures dépend non seulement des mesures mais aussi largement de l’endroit où elles sont appliquées., Cost-Effectiveness Analysis for controlling Non Point Source pollution by pesticidesThe EU Water Framework Directive (2000/60/EC) requires policy to address non-point source pollution as part of an overall integrated strategy to improve the ecological and chemical status of water bodies. With the aim of comparing various agricultural measures to control pesticide pollution in surface waters, we propose a methodological framework for spatially-distributed Cost-Effectiveness analysis. We use the Soil and Water Assessment Tool (SWAT) model to assess the effectiveness of the measures applied and develop an aggregated bio-economic model to evaluate the costs of implementation and to identify synergies and trade-offs. This approach is applied to the Gers river basin in southwest France. Findings clearly demonstrated that cost and effectiveness of measures depend not only of measures themselves but largely of the location of their implementation. (JEL: Q530, Q15, Q25)