Biological and economical aspects of commercial intensive shrimp mariculture in Texas

Abstract

Data collected from a commercially operated intensive shrimp farm on the Texas coast were used to evaluate certain operational aspects of penaeid shrimp farming in Texas. These data then were incorporated in a simulation model to explore economic feasibility of various hypothetical production scenarios. Stocking densities of approximately 85,000/ha, 96,000/ha, 112,000/ha, and 195,000/ha gave no significant differences in growth rate, survival rate or food conversion ratio for Penaeus vannamei in 0.9-ha ponds. Harvest biomass increased with stocking density, but average shrimp weight decreased. Use of an intensive nursery-raceway system to produce two annual crops was compared via simulation with direct stocking of postlarvae into growout ponds to yield one crop. Both investment and operational costs were analyzed for three types each of greenhouse and raceway varying in price and useful life. Three growout-pond stocking densities and two farm sizes were evaluated for use with each combination of greenhouse and raceway. Investment costs ranged from $142,000 for the farm with 40-ha of water surface, using the least expensive greenhouse and raceway plus the lowest stocking density, co about $2,300,000 for the 125-ha farm utilizing the most expensive greenhouse and raceway and the highest stocking density in the growout ponds. Operational costs were $7.60 and $9.71, respectively, per 1000 1-g juvenile shrimp produced. Unless growth rate in ponds for the stocked juvenile shrimp was 1.3 gram per week or greater, direct stocking of postlarvae in ponds was economically superior. A hypothetical intensive farm of 40 ha, to be developed over 3 years, was used to explore factors affecting the economics of commercial shrimp farming. Two lengths of growing season, seven stocking densities, three operator-learning indices, two selling price patterns, six levels of planning horizon, two types of growth rate, and six levels of year-one survival rate were evaluated. Increased growing season, operator-learning index and stocking rate usually increased revenue more than cash expense. Shrimp prices in 1987 made shrimp farming less attractive than in 1979. This analysis indicates that intensive shrimp farming on the mid-Texas coast is not an attractive business, given present technology and shrimp prices.