On the dynamics of commercial shing and parameter identi cation

This paper has two main objectives. The rst is to develop dynamic models of commercial sheries di erent from the existing models. The industry is assumed to have a well de ned index of performance based on which it either invests or otherwise. We do not however, assume that the industry or rm is e cient or optimal in its operations. The hypotheses in the models are quite general, making the models applicable to di erent management regimes. The second is that a new approach of tting model dynamics to time series data is employed to simultaneously estimate the poorly known initial conditions and the parameters of the nonlinear sheries dynamics. The approach is a data assimilation technique known as the adjoint method. Estimation of the poorly known initial conditions is one of the attractive features of the adjoint method. Unlike the conventional methods, the method employed in this paper, requires relatively less data. Economic parameters were reasonably estimated without cost and price data. The estimated equilibrium biomass is very close to the maximum sustainable biomass which means open access in this case led to economic over shing but not biological over shing. Department of Finance and Management Science, Norwegian School of Economics and Business Administration, Bergen Norway. Corresponding author: Tel. +4755959686, Fax . +4755959234, Email:[email protected]. Norwegian School of Economics and Business Administration, Bergen Norway. Foundation for Research in Economics and Business Administration, Bergen Norway. 1