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• 1. [Article] Indicators for Ecosystem Externalities in Fishing

  Ecosystem externalities arise when one use of an ecosystem affects its other uses through the production functions of the ecosystem. We use simulations from a size-spectrum ecosystem model to investigate ...

  Citation × Citation Citation Abstract Copy Title: Indicators for Ecosystem Externalities in Fishing Author: Andersen, Ken H., Vestergaard, Niels, Ravn-Jonsen, Lars Ecosystem externalities arise when one use of an ecosystem affects its other uses through the production functions of the ecosystem. We use simulations from a size-spectrum ecosystem model to investigate the ecosystem externality created by fishing of multiple species. The model is based upon general ecological principles and is calibrated to the North Sea. Two fleets are considered: a `forage fish’ fleet targeting species that mature at small sizes and a `large fish’ fleet targeting large piscivorous species. Based on the marginal analysis of the present value of the rent, we develop a benefit indicator that explicitly divides the consequences of fishing into internal and external benefits. This analysis demonstrates that the forage fish fleet has a notable economic impact on the large fish fleet, but the reverse is not true. The impact can be either negative or positive, which entails that for optimal economic exploitation, the forage fishery has to be adjusted according to the large fish fishery. With the present large fish fishery in the North Sea, the two fisheries are well adjusted; however, the present combined exploration level is too high to achieve optimal economic rents. Title: Indicators for Ecosystem Externalities in Fishing Author: Andersen, Ken H., Vestergaard, Niels, Ravn-Jonsen, Lars Ecosystem externalities arise when one use of an ecosystem affects its other uses through the production functions of the ecosystem. We use simulations from a size-spectrum ecosystem model to investigate the ecosystem externality created by fishing of multiple species. The model is based upon general ecological principles and is calibrated to the North Sea. Two fleets are considered: a `forage fish’ fleet targeting species that mature at small sizes and a `large fish’ fleet targeting large piscivorous species. Based on the marginal analysis of the present value of the rent, we develop a benefit indicator that explicitly divides the consequences of fishing into internal and external benefits. This analysis demonstrates that the forage fish fleet has a notable economic impact on the large fish fleet, but the reverse is not true. The impact can be either negative or positive, which entails that for optimal economic exploitation, the forage fishery has to be adjusted according to the large fish fishery. With the present large fish fishery in the North Sea, the two fisheries are well adjusted; however, the present combined exploration level is too high to achieve optimal economic rents. Close

• 2. [Article] Comprehensive Fishery Wealth: A Bioeconomic, Ecosystem-Based Approach to Measuring Fisheries Sustainability

  Fisheries sustainability is a much sought-after goal. Yet, “sustainability” is often too ambiguously defined to be of much practical guidance to policymakers. Furthermore, fisheries managers are increasingly ...

  Citation × Citation Citation Abstract Copy Title: Comprehensive Fishery Wealth: A Bioeconomic, Ecosystem-Based Approach to Measuring Fisheries Sustainability Author: Fenichel, Eli P., Abbott, Joshua K. Fisheries sustainability is a much sought-after goal. Yet, “sustainability” is often too ambiguously defined to be of much practical guidance to policymakers. Furthermore, fisheries managers are increasingly expected to assess and manage fisheries in an “ecosystem-based” manner – accounting for the ecological interdependencies of species and their coupling with the physical environment. We build upon the green accounting and sustainable development literatures to downscale indices often used to measure sustainability at the nation-state scale to measure the current and projected future sustainability of exploited fishery ecosystems. We argue that the sustainability of a fishery ecosystem can be assessed by whether the properly measured value of the natural, physical and human capital stocks embodied within the fishery (i.e., the comprehensive fishery wealth) is non-decreasing over time. We extend our published work (Fenichel and Abbott 2014) to show how ecosystem models of fisheries can be integrated with bioeconomic models of human “predators’” responses to changes in multispecies fish stocks and policy to provide rigorous “shadow prices” for all species within the system and fishing capital. These prices can then be multiplied by their associated capital stocks to provide an index of inclusive fishery wealth. Changes in this index (i.e., comprehensive investment) allow managers to assess the ability of past and current fishery management regimes to maintain wealth within the fishery for future generations. Finally, we show how our wealth accounting approach – when coupled with ecosystem-based bioeconomic models – can be leveraged to prospectively evaluate the sustainability and efficiency of alternative management approaches. Title: Comprehensive Fishery Wealth: A Bioeconomic, Ecosystem-Based Approach to Measuring Fisheries Sustainability Author: Fenichel, Eli P., Abbott, Joshua K. Fisheries sustainability is a much sought-after goal. Yet, “sustainability” is often too ambiguously defined to be of much practical guidance to policymakers. Furthermore, fisheries managers are increasingly expected to assess and manage fisheries in an “ecosystem-based” manner – accounting for the ecological interdependencies of species and their coupling with the physical environment. We build upon the green accounting and sustainable development literatures to downscale indices often used to measure sustainability at the nation-state scale to measure the current and projected future sustainability of exploited fishery ecosystems. We argue that the sustainability of a fishery ecosystem can be assessed by whether the properly measured value of the natural, physical and human capital stocks embodied within the fishery (i.e., the comprehensive fishery wealth) is non-decreasing over time. We extend our published work (Fenichel and Abbott 2014) to show how ecosystem models of fisheries can be integrated with bioeconomic models of human “predators’” responses to changes in multispecies fish stocks and policy to provide rigorous “shadow prices” for all species within the system and fishing capital. These prices can then be multiplied by their associated capital stocks to provide an index of inclusive fishery wealth. Changes in this index (i.e., comprehensive investment) allow managers to assess the ability of past and current fishery management regimes to maintain wealth within the fishery for future generations. Finally, we show how our wealth accounting approach – when coupled with ecosystem-based bioeconomic models – can be leveraged to prospectively evaluate the sustainability and efficiency of alternative management approaches. Close