Stocking density and date decisions in semi-intensive shrimp Litopenaeus vannamei (Boone, 1931) farming: a bioeconomic approach.

摘要

This article analyses the optimal selection of stocking density and date in semi-intensive culture of shrimp Litopenaeus vannamei (Boone, 1931). The empirical evaluation of productive and economic scenarios derived from the specific choice of these management variables is often unfeasible for decision makers. To overcome this limitation, the bioeconomic modelling is widely applicable in aquaculture systems. In the present study, profit maximization for a semi-intensive shrimp farm is obtained through the development of a bioeconomic model to analyse the combination of stocking density (range: 6-30 postlarvae (PL) m-2) and date (from March 1st to June 1st) as decision variables for a shrimp farm located in Sinaloa, Mexico. The results show that pond water temperatures prevailing during culture cycle when the stocking date is June 1st (temperature in 19-weeks culture period: 30.76+or-0.87 degrees C) and the stocking density is 20-24 PL m-2 produce a maximized Present Value Profit (PV pi ) of US$-ha 10 350 and PV pi US$-ha 2526 for weekly mortality rates at low (2.1%) and medium (5.8%) levels respectively. The marginal change in the cost of feed (+or-1%) has the greatest effect on PV pi (-0.58% and 0.59% respectively). The discussion focuses on the combined effect of mortality rate, stocking density and especially, on the stocking date decision, for a given production planning framework, taking into account that the stocking date is the main management decision variable to cope with viral diseases outbreaks.