The Experts below are selected from a list of 939 Experts worldwide ranked by ideXlab platform
Jon M. Conrad - One of the best experts on this subject based on the ideXlab platform.
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Bioeconomics of a marine disease
Marine Resource Economics, 2015Co-Authors: Jon M. Conrad, Daniel RondeauAbstract:We study the adaptive harvest of healthy stocks of shellfish that are faced with the risk of high natural mortality from a disease that is spreading along a coastline. This was the situation when Abalone Viral Ganglioneuritis (AVG) spread along the coast of Victoria, Australia in 2006. Abalone mortality on some reefs was thought to have been as high as 90%. In the face of an approaching virus, how should stocks at different reefs be managed? A stochastic, spatial bioeconomic model allows us to examine how optimal preemptive stock reductions are influenced by: (1) the probability of spread, (2) the mortality induced by AVG when it reaches a previously uninfected reef, (3) the form of the harvest cost function, and (4) a regime shift to lower biological productivity, post-AVG.
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Bioeconomics of a marine disease
Research Papers in Economics, 2014Co-Authors: Jon M. Conrad, Daniel RondeauAbstract:We study the economic impact of the viral disease AVG, its stochastic transmission across abalone reefs in southern Australia, and the optimal management response as AVG approaches an uninfected reef. Using conservative estimates of the virulence and mortality rates associated with the disease, we find it optimal to maintain the pre-AVG steady-state biomass on reef j until AVG has reached reef j - 1. The size of the optimal harvest when AVG has reached reef j - 1 is significant, ranging from 85% of the pre-AVG steady-state stock plus its annual growth, to 100% when the mortality rate associated with the virus reaches 80%. Increases in the probability of transmission, P, also increase the size of the drawdown but to a lesser extent than the mortality rate. A regime shift in the intrinsic growth rate following infection also plays a central role in determining the level of pre-emptive harvesting.
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nonspatial and spatial models in Bioeconomics
Natural Resource Modeling, 2012Co-Authors: Jon M. Conrad, Martin D SmithAbstract:Beginning in the 1960s, ecologists, mathe- maticians, and economists started developing a class of mod- els, which today are referred to as bioeconomic models. These early models started with a difference or differential equation describing the dynamics of a biological resource. To this equa- tion one might add a second difference or differential equation describing the dynamics of "harvesting effort." Alternatively, one could formulate a dynamic optimization problem seeking to maximize discounted net benefit. These models provided important insights into the tragedy of the commons and poli- cies that might promote optimal management. By the 1970s, more complex models were developed incorporating multi- species interactions, age-structured populations, and models with stochastic growth. In the late 1990s, spatial bioeconomic models were developed in recognition of the importance of location when managing biological resources. The objectives of this survey are to: (i) review some of the early models in Bioeconomics, (ii) present some of the key spatial models in Bioeconomics that have been used to assess the value of ma- rine (no-take) reserves, and (iii) speculate on the direction of future research in spatial Bioeconomics.
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The Bioeconomics of Marine Sanctuaries
Journal of Bioeconomics, 1999Co-Authors: Jon M. ConradAbstract:Consider an offshore fishing grounds of size K. Suppose the grounds has been overfished to the point that net revenue has been driven to zero and the fishery is in open access equilibrium at (X_∞, Y_∞). A marine sanctuary, where fishing is prohibited, is then created. Suppose the marine sanctuary is of size K_2 and that fishing is allowed on a smaller grounds, now of size K_1, where K_1 + K_2 = K. In the first, deterministic, model, the present value of net revenue from the grounds-sanctuary system is maximized subject to migration (diffusion) of fish from the sanctuary to the grounds. The size of the sanctuary is varied, the system is re-optimized, and the populations levels, harvest, and value of the fishery is compared to the 'no-sanctuary' optimum, and the open access equilibrium. In the deterministic model, a marine sanctuary reduces the present value of the fishery relative to the 'ideal' of optimal management of the original grounds. In the second model net growth is subject to stochastic fluctuation. Simulation demonstrates the ability of a marine sanctuary to reduce the variation in biomass on the fishing grounds. Variance reduction in fishable biomass is examined for different-sized sanctuaries when net growth on the grounds and in the sanctuary fluctuate independently and when they are perfectly correlated. For the stochastic model of this paper, sanctuaries ranging in size from 60 to 40% of the original grounds (0.6 ≥ K_2/K ≥ 0.4) had the ability to lower variation in fishable biomass compared to the no sanctuary case. For a sanctuary equal to or greater than 70% of the original grounds (K_2 ≥ 0.7K), net revenue would be nonpositive and there would be no incentive to fish.
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The Bioeconomics of Marine Sanctuaries
1997Co-Authors: Jon M. ConradAbstract:The role of a marine sanctuary, where commercial fishing might be prohibited, is evaluated in two models; one where net biological growth is deterministic, and the other where net biological growth is stochastic. There is diffusion (migration) between the sanctuary and the fishing grounds based on the ratios of current stock size to carrying capacity in each area. Fishing is managed under a regime of regulated open access. In the deterministic model, it is possible to determine the steady-state equilibrium and to assess its local stability. In the stochastic model a steady state does not exist, but a stable joint distribution for the fish stock on the grounds and in the sanctuary is possible. The creation of a no-fishing marine sanctuary leads to higher population levels on the grounds and in the sanctuary, and appears to reduce the variation of the population in both areas. The higher population levels and reduced variation has an opportunity cost; foregone harvest from the sanctuary.
Viktoria Schneider - One of the best experts on this subject based on the ideXlab platform.
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the Bioeconomics of marine reserves a selected review with policy implications
Journal of Bioeconomics, 2005Co-Authors: Quentin R Grafton, Tom Kompas, Viktoria SchneiderAbstract:The paper ‘bridges the divide’ between the biological and economic literature on marine reserves. It provides a selected review of the traditional use of reserves, the early reserve literature, the potential benefits of reserves, spillovers from reserves to harvested areas and bioeconomic models of marine reserves. The Bioeconomics literature is examined from the perspectives of deterministic models, spatial economic models and models that include uncertainty and stochasticity. Insights from the review are used to provide management implications in terms of reserve design, stakeholder cooperation and process, reserve-fishery transfers, traditional management controls, and ecosystem approaches to managing fisheries. Copyright Springer 2005
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the Bioeconomics of marine reserves a selected review with policy implications
Journal of Bioeconomics, 2005Co-Authors: Quentin R Grafton, Tom Kompas, Viktoria SchneiderAbstract:The paper ‘bridges the divide’ between the biological and economic literature on marine reserves. It provides a selected review of the traditional use of reserves, the early reserve literature, the potential benefits of reserves, spillovers from reserves to harvested areas and bioeconomic models of marine reserves. The Bioeconomics literature is examined from the perspectives of deterministic models, spatial economic models and models that include uncertainty and stochasticity. Insights from the review are used to provide management implications in terms of reserve design, stakeholder cooperation and process, reserve-fishery transfers, traditional management controls, and ecosystem approaches to managing fisheries.
James E Wilen - One of the best experts on this subject based on the ideXlab platform.
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Bioeconomics of managed relocation
Journal of the Association of Environmental and Resource Economists, 2016Co-Authors: David M Kling, James N Sanchirico, James E WilenAbstract:AbstractManaged relocation is a biological resource management intervention that moves a portion of a species negatively affected by climate change to sites outside of its historic range where the species’ productivity is expected to be higher. We numerically solve for the optimal managed relocation policy in a spatial-dynamic bioeconomic model. The model includes three sites where climate change causes the local productivity of a beneficial species to change over time. The optimal policy is characterized by complex transient dynamics that reflect productivity trends, the local benefit of the species, and the cost of relocation. Given concerns about the impact of a relocated species on destination ecosystems, we consider the implications of blocking relocation to a site. We also compare optimal managed relocation to the relocation policy that achieves a future population distribution with the least investment.
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marine reserves with endogenous ports empirical Bioeconomics of the california sea urchin fishery
Marine Resource Economics, 2004Co-Authors: Martin D Smith, James E WilenAbstract:Marine reserves are gaining substantial public support as tools for commercial fisheries management. Harvest sector responses will influence policy performance, yet biological studies often depict harvester behavior as spread uniformly over fishing grounds and unresponsive to economic opportunities. Previous bioeconomic analyses show that these behavioral assumptions are inconsistent with empirical data and, more importantly, lead to overly optimistic predictions about harvest gains from reserves. This paper adds another layer of behavioral realism to the Bioeconomics of marine reserves by endogenizing fisher home port choices with a partial adjustment share model. Estimated with Seemingly Unrelated Regression over monthly data, this approach allows simulation of both short- and long-run behavioral response to changes induced by marine reserve formation. The findings cast further doubt on the notion that marine reserves generate long-run harvest benefits.
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Bioeconomics of spatial exploitation in a patchy environment
Journal of Environmental Economics and Management, 1999Co-Authors: James N Sanchirico, James E WilenAbstract:Abstract This paper presents a model of renewable resource exploitation that incorporates both intertemporal dynamics and spatial movement. The model combines the H. S. Gordon–Vernon Smith hypothesis of a rent dissipation process with Ricardian notions that resources are exploited across space in a pattern dependent upon relative profitabilities. The population structure is characterized in a manner consistent with modern biological ideas that stress patchiness, heterogeneity, and interconnections among and between patches. Generally, we find the equilibrium patterns of biomass and effort across the system to be dependent upon bioeconomic conditions within each patch and the nature of the biological dispersal mechanism between patches. We use simple examples to illustrate how the distribution of effort throughout the system reflects the heterogeneity and the spatial biological linkages.
Quentin R Grafton - One of the best experts on this subject based on the ideXlab platform.
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the Bioeconomics of marine reserves a selected review with policy implications
Journal of Bioeconomics, 2005Co-Authors: Quentin R Grafton, Tom Kompas, Viktoria SchneiderAbstract:The paper ‘bridges the divide’ between the biological and economic literature on marine reserves. It provides a selected review of the traditional use of reserves, the early reserve literature, the potential benefits of reserves, spillovers from reserves to harvested areas and bioeconomic models of marine reserves. The Bioeconomics literature is examined from the perspectives of deterministic models, spatial economic models and models that include uncertainty and stochasticity. Insights from the review are used to provide management implications in terms of reserve design, stakeholder cooperation and process, reserve-fishery transfers, traditional management controls, and ecosystem approaches to managing fisheries. Copyright Springer 2005
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the Bioeconomics of marine reserves a selected review with policy implications
Journal of Bioeconomics, 2005Co-Authors: Quentin R Grafton, Tom Kompas, Viktoria SchneiderAbstract:The paper ‘bridges the divide’ between the biological and economic literature on marine reserves. It provides a selected review of the traditional use of reserves, the early reserve literature, the potential benefits of reserves, spillovers from reserves to harvested areas and bioeconomic models of marine reserves. The Bioeconomics literature is examined from the perspectives of deterministic models, spatial economic models and models that include uncertainty and stochasticity. Insights from the review are used to provide management implications in terms of reserve design, stakeholder cooperation and process, reserve-fishery transfers, traditional management controls, and ecosystem approaches to managing fisheries.
Tom Kompas - One of the best experts on this subject based on the ideXlab platform.
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the Bioeconomics of marine reserves a selected review with policy implications
Journal of Bioeconomics, 2005Co-Authors: Quentin R Grafton, Tom Kompas, Viktoria SchneiderAbstract:The paper ‘bridges the divide’ between the biological and economic literature on marine reserves. It provides a selected review of the traditional use of reserves, the early reserve literature, the potential benefits of reserves, spillovers from reserves to harvested areas and bioeconomic models of marine reserves. The Bioeconomics literature is examined from the perspectives of deterministic models, spatial economic models and models that include uncertainty and stochasticity. Insights from the review are used to provide management implications in terms of reserve design, stakeholder cooperation and process, reserve-fishery transfers, traditional management controls, and ecosystem approaches to managing fisheries. Copyright Springer 2005
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the Bioeconomics of marine reserves a selected review with policy implications
Journal of Bioeconomics, 2005Co-Authors: Quentin R Grafton, Tom Kompas, Viktoria SchneiderAbstract:The paper ‘bridges the divide’ between the biological and economic literature on marine reserves. It provides a selected review of the traditional use of reserves, the early reserve literature, the potential benefits of reserves, spillovers from reserves to harvested areas and bioeconomic models of marine reserves. The Bioeconomics literature is examined from the perspectives of deterministic models, spatial economic models and models that include uncertainty and stochasticity. Insights from the review are used to provide management implications in terms of reserve design, stakeholder cooperation and process, reserve-fishery transfers, traditional management controls, and ecosystem approaches to managing fisheries.