Qualitative Viablility Analysis of a Bio-Socio-Economic System

Although under some kind of management regime, many fisheries worldwide are under extreme pressure. By applying qualitative modelling techniques and bridging them to viability theory, this paper addresses two threads of the debate on sustainable fisheries: participatory management frameworks and ’ichtyocentric’ control strategies. We set up a model of a management framework, composed of an economic, an ecological and a political part, upon which viability criteria are imposed. These are assessed by allowing free chatter for a control variable and focussing simulation on a certain region of the qualitative phase space. It is investigated how different management strategies change the structure of the resulting state transition graph. It turns out that the viability of the system can only be achieved partially. However, it is demonstrated that a qualitative viability analysis can be a helpful first step for the design of controllers or the assessment of management frameworks.