Application of holistic and analytical models for the management of tilapia fisheries in reservoirs

Resumo

Reservoir fisheries are widely disseminated around the world. Their scarcely regulated exploitation justifies the use of models to achieve a precautory management. As an example of the utility of holistic and analytic models to analyse reservoir fisheries, it is presented the specific case of the tilapia fishery in the Infiernillo reservoir in Mexico. Schaefer and Fox models permitted an understanding of the history of fishery, while the current state of the stock was examined by applying Beverton & Holt, Cohort Analysis of Jones and Thompson & Bell models. Recommendations for the management of the fishery were based on simulation processes. Applying those models, it was found that the tilapia fishery surpassed its sustainable yield in 1988. In 1993 the fishery reached a new state of equilibrium. At present the fishery is in a deteriorated state. The fishing impact is on organisms in the reproductive stage. The current maximum sustainable yield is 8,698 tons. Simulation processes show that an increase in the mesh of the gill nets up to 10 cm and a decrease in the fishery effort down to 20,000 gill nets and 3,100 fishermen could help the fishery to recuperate. Holistic and analytical models are useful to evaluate reservoir fisheries.