Dynamic optimal ration size in tilapia culture: Economic and environmental considerations

Fish producers are facing high costs of food which rank between 30–60% out of total production costs. Optimal ration sizes are needed to improve management strategy by integrating technical-economic efficiency and minimizing environmental impacts. In contrast with the usual feeding practices in a farm and others consisting on normalized constant ratios, on this work non-constant optimal ration sizes throughout a culture cycle are determined. To do this, a bioeconomic model and the optimal control theory were employed. The model was parameterized for the case of farmed tilapia culture in Mexico and a potential type growth equation was selected. Optimal ration size trajectories were calculated for different destination markets (Monterrey, Mexico City, Cancun and On site) and different harvest sizes (200, 300 and 400 g). The higher net profit was obtained in the Monterrey market with 3,401.00USD/tank for tilapia of 400 g, whereas for sizes 300 and 200 g in Cancun the higher net profits were 2,505.04USD/tank and 1804.61USD/tank respectively. Likewise, produce small organisms to the markets of On site and Cancun generate less TAN and produce bigger fishes to the markets of Mexico and Monterrey increase TAN generate. We also present a discussion on the economic and ecological implications of optimal ration and decisions focused to the market management of tilapia.