Storage and viability of a fishery with resource and market dephased seasonalities

In this study we analyse the role of the storage regulation in a fishery's production process when the resource exploited and the market to which the production is exported are characterized by seasonal dephased oscillations. For this purpose we built up a dynamic model drawn from the French Guyana shrimp fishery example. The underlying objective of the model is not the maximisation of a given criterion (as would be in the optimal control approach), but merely the maintenance of the fishery's economical viability. The fundamental principle is here to try to preserve as many as possible viable control options. The conditions to achieve and maintain this viability are captured in a certain number of constraints. The analysis points out periods and situations within the season where the fishermen must anticipate the evolution of their storage to avoid violating those viability constraints. The study also indicates how the fishery's viability can be ensured even if the exploitation costs exceed the commercial value of the landings for a finite part of the year. However, when the resource's and/or market's oscillations are too large, the fishery may be not viable any longer and it appears that the crisis can not be removed by investing in larger storage capacities.