A bioeconomic analysis of an age-structured fish stock continuous in time and age

Abstract

An age-structured bioeconomic model, that is completely continuous in state and time, is developed. To make the model more realistic, a nonlinear recruitment function is introduced and steady state solutions are studied analytically. The objective is to maximize discounted net revenue. As the combination of continuous state and time requires solving partial differential equations, the analytical study has been complemented with numerical results. The main objective of numerical simulations is to investigate how optimal harvesting patterns vary with different assumptions and parameter values. In particular the purpose is to find out how persistent pulse fishing patterns are when we use this kind of modeling framework. Main emphasis is put on cost and demand parameters. The main results from the analysis are that pulse fishing patterns are highly sensitive both to cost and demand parameters, and pulse fishing tend to disappear completely when there is a significant relationship between price and quantity.