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• 1. [Article] The Economic Cost of Ignoring Fishery Induced Evolution

  Ecologists warn that the rapid evolution occurring as a result of high-intensity commercial fishing could have potentially disastrous economic and ecological effects. The evolution of economically relevant ...

  Citation × Citation Citation Abstract Copy Title: The Economic Cost of Ignoring Fishery Induced Evolution Author: Faig, Amanda D. Ecologists warn that the rapid evolution occurring as a result of high-intensity commercial fishing could have potentially disastrous economic and ecological effects. The evolution of economically relevant life-history traits in fish, which can occur due to the harvesting pressure from commercial fisheries, can irreversibly diminish fisheries yields and ecological services. I model the interactions between the genetics, population structure, and economics of the fishery in order to determine whether the economic implications of this rapid evolution (called fisheries-induced evolution or FIE) are as potentially consequential as ecologists predict. My model is based on North-East Arctic Cod, which are long lived and for which an abundance of information exists, including proof of FIE. I compare the steady state reached by a `myopic’ fishery manager who sets effort and mesh size policy while ignoring evolution, to one who dynamically optimizes his strategy with the knowledge of how evolution will respond. This paper shows that ignoring evolution may lead to some profit loss, but not likely the `catastrophic’ amount of loss predicted by biologists. While the value of the fishery is somewhat improved when evolution is accounted for, an important auxiliary benefit of accounting for evolution is that the fish stock is healthier, with a larger biomass and a more balanced age-structure. Thus while, in a narrow sense, accounting for the evolutionary effects of fishing may yield only modest gains in the present value of returns, there may be broader reasons for fisheries managers to adopt policies that incorporate knowledge of FIE. Title: The Economic Cost of Ignoring Fishery Induced Evolution Author: Faig, Amanda D. Ecologists warn that the rapid evolution occurring as a result of high-intensity commercial fishing could have potentially disastrous economic and ecological effects. The evolution of economically relevant life-history traits in fish, which can occur due to the harvesting pressure from commercial fisheries, can irreversibly diminish fisheries yields and ecological services. I model the interactions between the genetics, population structure, and economics of the fishery in order to determine whether the economic implications of this rapid evolution (called fisheries-induced evolution or FIE) are as potentially consequential as ecologists predict. My model is based on North-East Arctic Cod, which are long lived and for which an abundance of information exists, including proof of FIE. I compare the steady state reached by a `myopic’ fishery manager who sets effort and mesh size policy while ignoring evolution, to one who dynamically optimizes his strategy with the knowledge of how evolution will respond. This paper shows that ignoring evolution may lead to some profit loss, but not likely the `catastrophic’ amount of loss predicted by biologists. While the value of the fishery is somewhat improved when evolution is accounted for, an important auxiliary benefit of accounting for evolution is that the fish stock is healthier, with a larger biomass and a more balanced age-structure. Thus while, in a narrow sense, accounting for the evolutionary effects of fishing may yield only modest gains in the present value of returns, there may be broader reasons for fisheries managers to adopt policies that incorporate knowledge of FIE. Close

• 2. [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