• Assimilation of time series data into a dynamic bioeconomic fisheries model : an application to the North East Arctic cod stock 

      Ussif, Al-Amin M.; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2003-01)
      This paper combines the elegant technique of Data Assimilation and a Monte Carlo procedure to analyze time series data for the North East Arctic Cod stock (NEACs). A simple nonlinear dynamic resource model is calibrated ...
    • Continuous harvesting costs in sole-owner fisheries with increasing marginal returns 

      Sandal, Leif Kristoffer; Steinshamn, Stein Ivar; Maroto, Jose M.; Moran, Manuel (Working paper, Working paper, 2009-06)
      We develop a bioeconomic model to analyze a sole-owner fishery with fixed costs as well as a continuous cost function for the generalized Cobb-Douglas production function with increasing marginal returns to effort level. ...
    • Dynamic cournot-competitive harvesting of a common pool resource 

      Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2003-01)
      A variant of the classical harvesting game, where a number of competing agents simultaneously harvest a common-pool natural resource, is analysed. The harvesting at each time is a Cournot competition. The critical assumption ...
    • Economic evaluation of the fisheries policies in Denmark, Iceland and Norway : some performance indicators 

      Arnason, Ragnar; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar; Vestergaard, Niels (Working Paper, Working paper; Working paper, 2002-08)
      The economic efficiency of the Danish, Icelandic and Norwegian cod fisheries is examined. For this purpose nonlinear aggregate models of these three fisheries are constructed. A particular mathematical approach to calculate ...
    • Estimation of biological and economic parameters of a bioeconomic fisheries model using dynamical data assimilation 

      Ussif, Al-Amin M.; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2002-03)
      A new approach of model parameter estimation is used with simulated measurements to recover both biological and economic input parameters of a natural resource model. The data assimilation technique is the variational ...
    • Fish wars on the high seas : a straddling stock competition model 

      McKelvey, Robert W.; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2001-04)
      The post World War II era saw the development of powerful self-contained fishing fleets, so-called distant-water fleets (DWFs), which roamed the world’s oceans, seeking out rich harvesting targets wherever they might be ...
    • Fish wars on the high seas : erecting economic barriers to entry 

      McKelvey, Robert W.; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working paper, Working paper; Working paper, 2000-10)
      The 1993 U.N. Straddling Stock Agreement prescribes a multi-national organizational structure for management of an exploited marine fish stock, one whose range straddles both “Extended Economic Zones” (EEZs) and high seas ...
    • Implications of a nested stochastic/deterministic bio-economic model for a pelagic fishery 

      McDonald, A. David; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2001-05)
      Use is made of an economically optimal feedback rule to determine optimal levels of exploitation of a pelagic fish species. Data from the southern bluefin tuna fishery for the years 1960 - 1996 are utilised to apply this ...
    • Long-term sustainable and optimal management of multispecies stochastic fisheries 

      Poudel, Diwakar; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar; Kvamsdal, Sturla Furunes (Working papers;01/14, Working paper, 2014-02)
      Multispecies fisheries management is the first step towards ecosystem-based fisheries management. Multispecies management accounts for a number of species and their physical, biological, and economic interactions. These ...
    • On the dynamics of commercial fishing and parameter identification 

      Ussif, Al-Amin M.; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2002-03)
      This paper has two main objectives. The first is to develop a dynamic model of commercial fisheries different from most existing models that assume optimizing behavior. The industry is assumed to have a well-defined index ...
    • Optimal age-structured harvest in a dynamic model with heterogenous capital 

      Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper, 2003-08)
      A dynamic optimization model with four state variables and two control variables is developed in order to analyze a fishery where on fleet-segment is targeting young fish and another fleet-segment is targeting older fish ...
    • Optimal feedback controls : comparative evaluation of the cod fisheries in Denmark, Iceland and Norway 

      Arnason, Ragnar; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar; Vestergaard, Niels (Working paper, Working paper; Working paper, 2000-01)
      The purpose of this paper is to compare the relative efficiency of the fish harvesting policies of Iceland, Norway and Denmark. We have chosen to concentrate on the cod fishery as this is the single most important fishery ...
    • Optimal population and capital dynamics in fisheries with irreversible investments 

      Sandal, Leif Kristoffer; Steinshamn, Stein Ivar; Hoff, Ayoe (Working paper, Working paper, 2007-06)
      A multi-dimensional, non-linear dynamic model in continuous time is presented for the purpose of finding the optimal combination of exploitation and capital investment in optimal renewable resource management. Non-malleability ...
    • The premium of marine protected areas : a simple valuation model 

      Kvamsdal, Sturla Furunes; Sandal, Leif Kristoffer (Working paper, Working paper, 2007-03)
      Marine Protected Areas are considered as a hedging tool against some of the uncertainties that trouble many fisheries today. Such tools are always connected with a cost; a premium. An optimal harvest rule is combined with ...
    • Regional fisheries management on the high seas : the hit-and-run interloper model 

      McKelvey, Robert W.; Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper; Working paper, 2002-08)
      The 1993 U.N. Straddling Stock Agreement prescribes a multi-national organizational structure for management of an exploited marine fish stock, one whose range straddles both "Extended Economic Zones" (EEZs) and high seas ...
    • A simplified feedback approach to optimal resource management 

      Sandal, Leif Kristoffer; Steinshamn, Stein Ivar (Working Paper, Working paper, 2001-09)
      Optimal exploitation of a renewable capital stock is derived as a feedback rule for a general dynamic optimisation problem with a single resource. By a feedback rule is meant that optimal exploitation is given as an explicit ...
    • The ensemble kalman filter for multidimensional bioeconomic models 

      Kvamsdal, Sturla Furunes; Sandal, Leif Kristoffer (Working papers;04/14, Working paper, 2014-03)
      To serve the needs for integrating economic considerations into management decisions in ecosystem frameworks, we need to build models that capture observed system dynamics and incorporate existing knowledge of ecosystems ...