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Estimation of parameters in the drift and diffusion terms of stochastic differential equations involves simulation and generally requires substantial data sets. We examine a method that can be applied when available time series are limited to less than 20 observations per replication. We compare and contrast parameter estimation for linear and nonlinear(More)
A new approach of model parameter estimation is used with simulated measurements to recover bothbiological and economic input parameters of a natural resource model. The procedure eeciently combines time series of observations with a simple bioeconomic sheries model to optimally estimate the model parameters. Using identical twin experiments , it is shown(More)
The Lotka-Volterra predator-prey model exemplifies the implicit and explicit assumptions managers often have regarding species interaction—popu-lations are stable or fluctuate periodically. The reality is often much more complicated and there is overwhelming evidence that many populations fluctuate in a nonperiodic way. Using a discrete predator-prey model(More)
In this paper we study how a stochastic model can be used to determine optimal levels of exploitation of the NorthEast Arctic Cod (NEAC , Gadus morhua). A non-critical depensation growth model is developed for this species in order to examine both deterministic and stochastic cases. Estimation of the biological and the noise term parameters in the(More)
This paper combines the new and elegant technique of inverse methods and a Monte Carlo procedure to analyze real data for the Norwegian cod shery (NCF) stock. A simple nonlinear dynamic resource model is calibrated to real time series of observations using the adjoint parameter estimation method of data assimilation and the Monte Carlo technique. By(More)
A non-traditional approach of tting dynamic resource biomass models to data is developed in this paper. The adjoint technique is an optimal control or a variational method for parameter identiication. It provides a novel and eecient procedure for combining all available information in the analysis of a resource system. Two alternative population dynamics(More)
The thesis explores how the introduction of a marine protected area influences the optimal management of a marine resource, i.e. a fish stock. Logistic growth functions are applied to a deterministic model with a migration term which is proportional to the difference in density in the two areas. A nonlinear profit function is adopted. The possibility and(More)