Abstract
The scientific basis of fisheries management is often restricted to a biological analysis of the dynamics of fish stocks. This narrow focus has led to management strategies that ignore the dynamic responses of fisherman to changes in stocks or in changes to management itself (Hilborn and Walters, 1992) Further, the spatial scale of the fisheries exploitation generally does not coincide with the spatial scale over which populations of marine organisms interact. In the North Sea, commercially exploited fish species such as cod, plaice and sole consist of different components that segregate during the spawning period but mix during the feeding season (de Veen, 1962, 1978; Daan, 1978). Since the North Sea is one management area, fishing fleets may move freely within this area and may exploit the component stocks of a species differentially. To study the spatial dynamics of fishing fleets we will adopt the approach to consider fishermen as predators that attempt to maximize their economic return (Hilborn, 1985; Hilborn and Walters, 1992; Abrahams and Healy, 1993; Gillis et al., 1993; Gillis and Peterman, 1998). This project will study the dynamics of the spatial distribution of Dutch beam trawl vessels using individual logbook data of the total fleet. The beam trawl fishery in the North Sea developed since the mid 1960s and is dominated by the Dutch fleet (Rijnsdorp and Millner, 1996; Daan, 1997). A number of specific question will be addressed that are all related to the spatial dynamics of effort allocation of the Dutch beam trawl fleet in relation to: § distribution and abundance of the main prey species (sole and plaice) § economic factors § responses of fishermen to specific management regulations such as changes in the TACs, the introduction of the co-management system and technical regulations such as the plaice box and mesh size regulations. The objective is to determine the main factors driving the spatial dynamics of effort allocation, and hence dictates the scale of human exploitation, and to build a simulation model of the fleet.
Netherlands