Stochastic bio-economic optimization of pond size for intensive commercial production of whiteleg shrimp Litopenaeus vannamei

• A bioeconomic approach was used for design optimization of intensive shrimp farms.
• A relationship was established between Net Present Value (NPV) and pond size.
• A relationship was established between Internal Rate of Return (IRR) and pond size.
• A relationship was established between Return per Unit Risk (RUR) and pond size.
• Ponds of 2 ha stocked at 60–90 postlarvae m− 2 maximized NPV, IRR and RUR.

We used a stochastic bio-economic model to define the optimum pond size for intensive, commercial production of whiteleg shrimp Litopenaeus vannamei. Optimization is based on economic performance and minimization of risk of farms (approximately 50 ha each) using pond sizes from 2–8 ha. Ponds of 2 ha maximized Net Present Value (NPV), Internal Rate of Return (IRR) and Return per Unit Risk (RUR). Mean NPV varied from US$ − 59,800 (8 ha pond size and 30% interest rate) to US$ 63,300 (2 ha pond size and 10% interest rate). RUR calculated for NPV varied from − 7.96 (8 ha pond size and 30% interest rate) to 1.79 (2 ha pond size and 10% interest rate). Positive values of mean NPV and RUR were projected for pond sizes lower than 4 ha (20% interest rate) and 5.5 ha (10% interest rate). Negative values of mean NPV and RUR were projected for all pond sizes when the interest rate was 30%. The results, when calculating IRR and the corresponding RUR, confirmed that pond size of 2 ha is optimum. Mean IRR varied from − 11.76% (8 ha pond size) to 25.31% (2 ha pond size), and RUR varied from − 2.62 (8 ha pond size) to 2.87 (2 ha pond size). Attractive values of mean IRR were projected for ponds smaller than 4 ha when the Minimum Attractive Rate of Return (MARR) was 20% and 5.5 ha when the MARR was 10%. No attractive values of mean IRR were projected when the MARR was 30%. Mean negative values of IRR and RUR were projected for ponds larger than approximately 6.3 ha. For ponds of 2 ha, we determined that there are 95, 50, and 5% probabilities of obtaining a MARR of at least 11.8, 25.2, and 34.6%, respectively. Alternative sizes of farms composed of 2 ha ponds indicated that economic risk decreased as farm size increased from 4 to 25 ponds. Despite higher construction costs, 2 ha ponds are recommended because of their better economic performance, due to larger shrimp size and greater biomass at harvest.