Title: Optimal harvesting of the Norwegian spring-spawning herring stock and a spatial model

Authors: Mitri Kitti, Marko Lindroos and Veijo Kaitala

Status: Systems Analysis Laboratory Research Reports E2 October 1999

In this report we study optimal harvesting of the Norwegian spring-spawning herring stock and present simulations using a spatial model for the population. Moreover, a game-theoretic approach for the harvesting of the stock is discussed briefly. The emphasis is on the optimisations. The biological model is described by a discrete time age structured model and the spatial model is based on the zonal distributions of the population. The optimal harvesting patterns are studied numerically and the results show that when using a linear cost function and constant price in the optimisation model, the optimal harvesting pattern is pulse fishing. The spatial model is studied briefly with an open access simulation and a simulation with constant fishing efforts.