Bioeconomic modeling and risk analysis of raising shrimp Litopenaeus vannamei in floating cages in northwestern Mexico: Assessment of hurricane hazard, stochastic variability of shrimp and feed prices, and zootechnical parameters

Risk analysis of shrimp cultivation in floating cages in northwestern Mexico was undertaken, including hurricane hazard, stochastic variability of shrimp and feed prices, and zootechnical parameters. We used a bioeconomic model to analyze risk and determine whether higher prices for shrimp following the hurricane season (November) would compensate for the risk of hurricane impact. The expectation of net revenue above operating costs and the benefit–cost ratio were maximized by testing the size of the coastal area under potential hurricane impact, partial harvesting, alternative seeding-harvesting schedules, stocking density, and duration of cultivation. A production unit of 50 cages was used for analysis. When cultivation was not affected by hurricanes, the highest net revenue and return per unit risk (RUR) were obtained by conducting partial-and-final harvests in October and November. No significant linear trend was detected in the hurricane frequency (P = 0.74) from 1970 through 2009 and, depending on the size of the coastal area of potential hurricane impact, the monthly probabilities of hurricane impact were 2.5% (August), 25%–30% (September), and 17.5%–27.5% (October). Hurricane season ends in late October with 40% to 55% probability of not being affected by hurricanes. When cultivation was affected by hurricanes, net revenue and RUR were lower than when hurricanes were not a factor. Using partial-and-final harvests and the May to August–September and July to October–November schedules, the only alternatives offering profit and highest RUR tended to compensate for the risk associated with the impact of hurricanes. In this case, the maximum net revenue was US$9200 ha−1. Risk and sensitivity analyses showed that annual variability of shrimp price, mortality during the second phase of cultivation and hurricane hazard were the most important risk factors. For a cultivation cycle with a single harvest, net revenue and benefit–cost ratio were maximized by using 1350 postlarvae m−2 (at the nursery), and 300 juveniles m−2 and 60 days (for grow-out). For a cycle with partial-and-final harvests, maximization was obtained using 1500 postlarvae m−2 (at the nursery), 580 juveniles m−2 (phase 1 of grow-out), 335 shrimp m−2 (phase 2 of grow-out), and the maximum duration of the phases (60 and 30 days). Highly intensive rearing techniques, partial harvesting, long cultivation periods, and seeding at least 90 days before the start of the hurricane season are recommended to improve net revenue expectations.