Analysis of ration size in Nile tilapia production: Economics and environmental implications

This article aims to identify the best management strategy for integrating technical-economic efficiency and ecological impact when a rural producer of Nile tilapia faces problems with fixed price and harvest size. A bioeconomic model was developed based on an experimental study of juvenile tilapia growth with three rations, as recommended by the feed suppliers, and a satiation ration (producer's strategies). The model included standardized rations from 0 to 1, where 0 indicates starvation and 1 satiation. Three harvest sizes and two market conditions (fixed price and size-dependent price), projecting the Net Present Value (NPV) and Total Ammoniacal Nitrogen (TAN) production of the culture rotations over 10 years were simulated. For the size-dependent price, the greatest NPV was reached for a harvest size of 300 g (ration of 0.75) and for the fixed price the recommended size was 200 g (ration of 0.67). The optimum rations are below that recommended by feed providers (0.84). With the recommended optimum ration and harvest size, TAN production can be reduced to 1.88 t (54.33%) in the same time period. (C) 2013 Elsevier B.V. All rights reserved.