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• 1. [Article] Generalization of Age-Structured Models in Theory and Practice

  A generalization of the harvesting functions and the stock updating functions in age-structured bioeconomic models is outlined. Using this generalization everything from completely uniformly distributed ...

  Citation × Citation Citation Abstract Copy Title: Generalization of Age-Structured Models in Theory and Practice Author: Steinshamn, Stein Ivar A generalization of the harvesting functions and the stock updating functions in age-structured bioeconomic models is outlined. Using this generalization everything from completely uniformly distributed fish to extreme schooling is taken care of. The classical Beverton-Holt model comes out as a special case of the generalized model. Both the theoretical outline as well as practical numerical examples are provided, and the generalization can be applied both for simulation as well as optimization purposes given appropriate software. Here we apply advanced non-linear programming to maximize the net present value in a bioeconomic setting where the new updating and harvesting functions are used as constraints. This is possible thanks to new software, such as KNITRO, for solving highly nonlinear problems. Applications of this generalized model produce interesting new results. One such practical result is that pulse fishing seems to become less and less economically profitable as we move from uniformly distributed fish to schooling species. The main reason why pulse fishing cease to be optimal in schooling fisheries, is that the economies of scale present in search fisheries gradually disappear when we move from search fisheries to schooling fisheries. This may have important implications for how fish stocks ought to be managed in the future, especially with respect to total allowable catches based on bioeconomic criteria. Title: Generalization of Age-Structured Models in Theory and Practice Author: Steinshamn, Stein Ivar A generalization of the harvesting functions and the stock updating functions in age-structured bioeconomic models is outlined. Using this generalization everything from completely uniformly distributed fish to extreme schooling is taken care of. The classical Beverton-Holt model comes out as a special case of the generalized model. Both the theoretical outline as well as practical numerical examples are provided, and the generalization can be applied both for simulation as well as optimization purposes given appropriate software. Here we apply advanced non-linear programming to maximize the net present value in a bioeconomic setting where the new updating and harvesting functions are used as constraints. This is possible thanks to new software, such as KNITRO, for solving highly nonlinear problems. Applications of this generalized model produce interesting new results. One such practical result is that pulse fishing seems to become less and less economically profitable as we move from uniformly distributed fish to schooling species. The main reason why pulse fishing cease to be optimal in schooling fisheries, is that the economies of scale present in search fisheries gradually disappear when we move from search fisheries to schooling fisheries. This may have important implications for how fish stocks ought to be managed in the future, especially with respect to total allowable catches based on bioeconomic criteria. Close

• 2. [Article] Viability of Transboundary Fisheries and International Quota Sharing

  This paper examines the viability of the management of a transboundary resource, the Bay of Biscay anchovy (Engraulis encrasicolus L.). A deterministic model is used to simulate the anchovy dynamics, with ...

  Citation × Citation Citation Abstract Copy Title: Viability of Transboundary Fisheries and International Quota Sharing Author: Curtin, Richard, Martinet, Vincent This paper examines the viability of the management of a transboundary resource, the Bay of Biscay anchovy (Engraulis encrasicolus L.). A deterministic model is used to simulate the anchovy dynamics, with the fish stock consisting of two age groups, “young" and “old", while recruitment follows a Beverton Holt pattern. Two countries, France and Spain, harvest the resource, with two different types of gear, the purse seiner for Spain and the pelagic trawler for France. These technologies impact the different age-groups of anchovy at differing rates. A regulatory agency defines an annual fishing quota and its allocation between the two countries, with the aim of sustainability in the overall allocation design. A set of constraints is defined to describe the sustainability of the system which encompasses the economic, ecological and social aspects of the fishery. The optimal harvest share between the two countries is found and a number of scenarios are then tested in relation to their ability to remain within the set of constraints, or viability kernel. Other scenarios, including the historical trajectory, the optimal harvest share trajectory and the minimum time of crisis trajectory, are examined. Title: Viability of Transboundary Fisheries and International Quota Sharing Author: Curtin, Richard, Martinet, Vincent This paper examines the viability of the management of a transboundary resource, the Bay of Biscay anchovy (Engraulis encrasicolus L.). A deterministic model is used to simulate the anchovy dynamics, with the fish stock consisting of two age groups, “young" and “old", while recruitment follows a Beverton Holt pattern. Two countries, France and Spain, harvest the resource, with two different types of gear, the purse seiner for Spain and the pelagic trawler for France. These technologies impact the different age-groups of anchovy at differing rates. A regulatory agency defines an annual fishing quota and its allocation between the two countries, with the aim of sustainability in the overall allocation design. A set of constraints is defined to describe the sustainability of the system which encompasses the economic, ecological and social aspects of the fishery. The optimal harvest share between the two countries is found and a number of scenarios are then tested in relation to their ability to remain within the set of constraints, or viability kernel. Other scenarios, including the historical trajectory, the optimal harvest share trajectory and the minimum time of crisis trajectory, are examined. Close

• 3. [Article] Optimal Harvest in a Multispecies Age Structured Fishery Model at Different Level of Density Dependency

  Presentation

  Citation × Citation Citation Abstract Copy Title: Optimal Harvest in a Multispecies Age Structured Fishery Model at Different Level of Density Dependency Author: Poudel, Diwakar Presentation Title: Optimal Harvest in a Multispecies Age Structured Fishery Model at Different Level of Density Dependency Author: Poudel, Diwakar Presentation Close

• 4. [Article] Bioeconomic Modeling and Management of the Southern Bluefin Tuna Fishery

  The paper reviews the management and bioeconomic modeling of the Southern Bluefin Tuna stock. It describes two studies using simultaneous, non-cooperative, three player games to predict revenue and stock ...

  Citation × Citation Citation Abstract Copy Title: Bioeconomic Modeling and Management of the Southern Bluefin Tuna Fishery Author: Kennedy, John, Campbell, Harry The paper reviews the management and bioeconomic modeling of the Southern Bluefin Tuna stock. It describes two studies using simultaneous, non-cooperative, three player games to predict revenue and stock outcomes generated by a deterministic, discrete, age-structured model of the SBT population. Two versions of the model, corresponding to biological and harvesting conditions prevailing around 2000 and 2007 respectively are considered. Because of a significant downward revision of estimates of the productivity of the SBT stock between these two dates, the later model suggests that conservation and optimal utilization of the SBT stock will require a substantial cut in catch quotas as compared with the results of the earlier model. Title: Bioeconomic Modeling and Management of the Southern Bluefin Tuna Fishery Author: Kennedy, John, Campbell, Harry The paper reviews the management and bioeconomic modeling of the Southern Bluefin Tuna stock. It describes two studies using simultaneous, non-cooperative, three player games to predict revenue and stock outcomes generated by a deterministic, discrete, age-structured model of the SBT population. Two versions of the model, corresponding to biological and harvesting conditions prevailing around 2000 and 2007 respectively are considered. Because of a significant downward revision of estimates of the productivity of the SBT stock between these two dates, the later model suggests that conservation and optimal utilization of the SBT stock will require a substantial cut in catch quotas as compared with the results of the earlier model. Close

• 5. [Article] International Management Strategies for a Migratory Fish Stock: A Bio-economic Simulation Model of the Norwegian Spring-spawning Herring Fishery

  In this paper, a three-country dynamic bio-economic model is presented and used to simulate catch levels, stock size and profit potential of alternative management strategies for the Norwegian spring-spawning ...

  Citation × Citation Citation Abstract Copy Title: International Management Strategies for a Migratory Fish Stock: A Bio-economic Simulation Model of the Norwegian Spring-spawning Herring Fishery Author: Gordon, Daniel V., Bjorndal, Trond, Lindroos, Marko, Kaitala, Veijo Year: 2001 In this paper, a three-country dynamic bio-economic model is presented and used to simulate catch levels, stock size and profit potential of alternative management strategies for the Norwegian spring-spawning herring fishery. Management of the herring fishery is complicated by the migratory behaviour of the species moving between coastal state zones and the high seas. The biological model is described by a discrete time age structured model and the economic model is described by a rent maximising model with constant price of herring and different costs of harvesting and efficiency levels for the different national fleets. The simulations are carried out over a 70-year period and show that the benefits of international cooperation far exceed the returns of a competitive open access fishery. Title: International Management Strategies for a Migratory Fish Stock: A Bio-economic Simulation Model of the Norwegian Spring-spawning Herring Fishery Author: Gordon, Daniel V., Bjorndal, Trond, Lindroos, Marko, Kaitala, Veijo Year: 2001 In this paper, a three-country dynamic bio-economic model is presented and used to simulate catch levels, stock size and profit potential of alternative management strategies for the Norwegian spring-spawning herring fishery. Management of the herring fishery is complicated by the migratory behaviour of the species moving between coastal state zones and the high seas. The biological model is described by a discrete time age structured model and the economic model is described by a rent maximising model with constant price of herring and different costs of harvesting and efficiency levels for the different national fleets. The simulations are carried out over a 70-year period and show that the benefits of international cooperation far exceed the returns of a competitive open access fishery. Close

• 6. [Article] DATA MINING MULTIPLE STAKEHOLDERS’ RESPONSES TO DECLINING SCHIZOTHORAX FISHERY IN THE LAKES OF KASHMIR, INDIA

  Research paper and presentation

  Citation × Citation Citation Abstract Copy Title: DATA MINING MULTIPLE STAKEHOLDERS’ RESPONSES TO DECLINING SCHIZOTHORAX FISHERY IN THE LAKES OF KASHMIR, INDIA Author: Melake Araya, Tesfom, Sundaramoorthy, C., Quereshi, Neha W., Ramasubramanian, V., Krishnan, M. Research paper and presentation Title: DATA MINING MULTIPLE STAKEHOLDERS’ RESPONSES TO DECLINING SCHIZOTHORAX FISHERY IN THE LAKES OF KASHMIR, INDIA Author: Melake Araya, Tesfom, Sundaramoorthy, C., Quereshi, Neha W., Ramasubramanian, V., Krishnan, M. Research paper and presentation Close

• 7. [Article] Optimal Management of Conflicting Species: Grey Seal (Halichoerus grypus) and Atlantic Salmon (Salmo salar) in the Northern Baltic Sea

  In the Baltic Sea, the successful conservation of grey seals has increased seal-induced damages to the Atlantic salmon fishery. The paper addresses the conflict between the conservation of the formerly ...

  Citation × Citation Citation Abstract Copy Title: Optimal Management of Conflicting Species: Grey Seal (Halichoerus grypus) and Atlantic Salmon (Salmo salar) in the Northern Baltic Sea Author: Kulmala, Soile, Lindroos, Marko, Holma, Maija In the Baltic Sea, the successful conservation of grey seals has increased seal-induced damages to the Atlantic salmon fishery. The paper addresses the conflict between the conservation of the formerly endangered species and professional fishermen whose livelihood is also regulated by fisheries management. We develop a bioeconomic model that accounts for the age-structure of Atlantic salmon and grey seal populations. In order to reach a social optimum, we maximize the discounted net present value taking into account the seal-induced losses through a damage function. The socially optimal salmon stock size, salmon catch and fishing effort is studied under different management schemes aimed at mitigating the seal-salmon conflict. The results suggest that technological adaptation would effectively reduce the cause of the conflict, while a technology subsidy encouraging such adaptation shifts the economic responsibility from individual fishermen towards a broader public. Title: Optimal Management of Conflicting Species: Grey Seal (Halichoerus grypus) and Atlantic Salmon (Salmo salar) in the Northern Baltic Sea Author: Kulmala, Soile, Lindroos, Marko, Holma, Maija In the Baltic Sea, the successful conservation of grey seals has increased seal-induced damages to the Atlantic salmon fishery. The paper addresses the conflict between the conservation of the formerly endangered species and professional fishermen whose livelihood is also regulated by fisheries management. We develop a bioeconomic model that accounts for the age-structure of Atlantic salmon and grey seal populations. In order to reach a social optimum, we maximize the discounted net present value taking into account the seal-induced losses through a damage function. The socially optimal salmon stock size, salmon catch and fishing effort is studied under different management schemes aimed at mitigating the seal-salmon conflict. The results suggest that technological adaptation would effectively reduce the cause of the conflict, while a technology subsidy encouraging such adaptation shifts the economic responsibility from individual fishermen towards a broader public. Close

• 8. [Article] The Economics of Cooperative Fishery Research: A Survey of U.S. West Coast Groundfish Industry and Scientists

  Cooperative research, the active participation of industry in scientific research, is receiving increased attention as an alternative to traditional government-sponsored methods. Its strongest attributes ...

  Citation × Citation Citation Abstract Copy Title: The Economics of Cooperative Fishery Research: A Survey of U.S. West Coast Groundfish Industry and Scientists Author: Sylvia, Gil, Harms, John Year: 2001 Cooperative research, the active participation of industry in scientific research, is receiving increased attention as an alternative to traditional government-sponsored methods. Its strongest attributes are its potential to improve spatial and temporal collection of fishery data while reducing some research costs. Despite these potential benefits, there are obstacles to adopting cooperative research on a large scale including concerns about biased data, continuity with current data regimes, and the motivations of the participants. Acknowledging these limitations, this research examines the factors that influence industry's willingness to participate in cooperative research with fishery scientists. During summer 1998, scientists and fishermen in the U.S. West Coast groundfish fishery participated in a mail survey that asked respondents to assess several potential cooperative research projects on the basis of their perceived costs and benefits. Scientists and fishermen differed most strongly on “observer programs” and “interviewing fishermen to gather qualitative data.” The survey also included hypothetical scenarios where fishing vessels would be chartered for research. Fishermen assigned a "desirability" score and "willingness to supply" their vessel for research as a function of varying levels of compensation, days at sea, consultation into the design and conduct of the research, and other factors. Based on a utility of profit supply model, results were analyzed using ordinary least squares. Compensation and skipper consultation had the largest effect on the charter's desirability and respondents' willingness to supply. Age, education, and gear type also significantly affected fishermen's willingness to participate in the charters. These results suggest significant problems in the manner in which scientists and industry relate. Addressing these problems will require developing institutions with appropriate incentives that emphasize "win-win" scenarios for both groups. Title: The Economics of Cooperative Fishery Research: A Survey of U.S. West Coast Groundfish Industry and Scientists Author: Sylvia, Gil, Harms, John Year: 2001 Cooperative research, the active participation of industry in scientific research, is receiving increased attention as an alternative to traditional government-sponsored methods. Its strongest attributes are its potential to improve spatial and temporal collection of fishery data while reducing some research costs. Despite these potential benefits, there are obstacles to adopting cooperative research on a large scale including concerns about biased data, continuity with current data regimes, and the motivations of the participants. Acknowledging these limitations, this research examines the factors that influence industry's willingness to participate in cooperative research with fishery scientists. During summer 1998, scientists and fishermen in the U.S. West Coast groundfish fishery participated in a mail survey that asked respondents to assess several potential cooperative research projects on the basis of their perceived costs and benefits. Scientists and fishermen differed most strongly on “observer programs” and “interviewing fishermen to gather qualitative data.” The survey also included hypothetical scenarios where fishing vessels would be chartered for research. Fishermen assigned a "desirability" score and "willingness to supply" their vessel for research as a function of varying levels of compensation, days at sea, consultation into the design and conduct of the research, and other factors. Based on a utility of profit supply model, results were analyzed using ordinary least squares. Compensation and skipper consultation had the largest effect on the charter's desirability and respondents' willingness to supply. Age, education, and gear type also significantly affected fishermen's willingness to participate in the charters. These results suggest significant problems in the manner in which scientists and industry relate. Addressing these problems will require developing institutions with appropriate incentives that emphasize "win-win" scenarios for both groups. Close