SRAC Publication No. 4830 VI November 2005 PR Economics of Freshwater Prawn Farming in the United States Siddhartha Dasgupta1 Freshwater prawn (Macrobrachium Alabama with 60 acres. There are 20,000 eggs, which hatch into rosenbergii) farming in the United also a few prawn farms in prawn larvae in 3 weeks. Newly States has been predominantly a Arkansas, Georgia, Illinois, hatched larvae are kept in brack- small-scale aquaculture industry. Indiana, Louisiana and Ohio. ish water where they need pro- The U.S. industry started in During the 1980s and 1990s, 0.2 tein-rich feed such as zooplank- Hawaii in the 1960s, followed by to 0.4 million pounds of prawns ton. After 22 to 30 days, post- South Carolina in the 1970s and per year were produced in the larvae can be stocked in freshwa- Mississippi in the 1980s. Early U.S. The crop had an annual ter. The post-larvae are usually attempts at prawn culture were wholesale value of $0.89 million nursed for at least 30 more days. hampered by lack of seed stock to $2.54 million and the prices Then the juveniles are ready to be and problems in marketing the for whole prawns paid by proces- stocked into ponds for grow-out to end product. During the 1980s sors and other wholesale buyers adult prawns. and 1990s, researchers developed ranged from $4 to $7 per pound. The parameters of prawn produc- several elements important for the The price of Gulf of Mexico tion are industry’s growth, such as marine shrimp (tails only) • stocking density (number of improved hatchery and nursery declined from $7.00 per pound to technology, pond culture methods, juveniles stocked per acre of $4.50 per pound from 1995 to water), and post-harvest handling proto- 2002, which corresponded to an cols for quality control and prod- approximate price range of $2.25 • age of seed at stocking, uct preservation. As a result of to $3.50 per pound for whole • feeding or fertilization rate these and other efforts, several prawns. Similarly, the price of (pounds per acre per year successful prawn hatcheries and imported marine shrimp tails applied to a prawn pond), nurseries have been established in (comparable in size to freshwater • feed types, and the U.S. and more domestically prawns) declined from $7.00 per produced prawns are being mar- pound to $4.00 per pound (i.e., • presence of artificial substrates. keted than ever before. $2.00 to $3.50 per pound for Prawns are tropical animals and Prawn production in whole shrimp). At these prices, require water warmer than 65 ºF U.S. prawn producers could not to grow. The growth period from the U.S. compete in wholesale markets juvenile to a market-size adult is 4 In 1998, the states of Hawaii, and retail and direct sales were months (June to September) in South Carolina, Kentucky and their only marketing options. The temperate regions of the U.S. Florida had the most surface acres freshness of the domestic product Pond culture of prawns is done in devoted to prawn production. In was their main marketing asset. single annual batches during the summer and early fall. 2003, Mississippi had the most Prawn production methods water acres in prawns (600 acres), Proper pond management is a followed by Tennessee and Freshwater prawn production vital element of production suc- Kentucky with 200 acres each and occurs in three stages—hatchery, cess. Juvenile prawns are usually nursery and grow-out. In the stocked in late May or early June 1 Kentucky State University, Aquaculture hatchery stage, fertilized adult and fed a 32% crude protein sink- Research Center, Frankfort, KY. female prawns produce 10,000 to ing feed. Feeding rates depend on prawn age and are available from fence) to create more living area. mental results for low stocking feeding tables such as the one in Prawns are territorial and canni- densities have produced about D’Abramo et al. (2003). Ponds are balistic, so installing substrates 800 pounds per acre (Table 2). usually aerated nightly or 24 decreases mortality by allowing Low stocking densities in experi- hours a day. Adult prawns are the animals to distribute them- mental ponds also resulted in harvested by late September. selves more widely in the pond. large adult prawns—eight ani- mals per pound or 8-count whole Stocking densities in commercial Having more space also allows prawn—while commercial har- ponds have mostly ranged from prawns to grow larger. Experi- vest weights were approximately 8,000 to 30,000 per acre. Some mental yields from intensively 12 per pound or 12-count. farmers stock at low densities stocked ponds with substrates (8,000 to 10,000 per acre), which have been 2,000 to 3,000 pounds There were similar results for is commonly called extensive or per acre; however, commercial semi-intensive stocking densities. low-input culture. At low densi- yields have varied from 1,200 to Commercial yields (500 to 800 ties, prawns are fed at a rate of 2,000 pounds per acre. pounds per acre) trailed behind experimental yields (900 to 1,000 1,000 to 1,500 pounds per acre Experimental vs. per year. Supplemental aeration pounds per acre). Posadas (2004) may or may not be used. Data commercial production highlighted cases in which com- from Kentucky showed that when results mercial yields under semi-inten- ponds were not aerated yields sive and extensive production were 230 to 400 pounds per acre. Although commercial producers were similar, despite the almost Average yields in aerated ponds have tried to follow prawn man- two-fold stocking difference. The ranged from 300 to 600 pounds agement methods developed at reason was that semi-intensive per acre. aquaculture experiment stations stocking densities produced in the U.S., small-scale commer- smaller prawns (14-count average Many producers use a semi-inten- cial ponds are usually no match size) than extensive production sive stocking density (15,000 to for well-supplied and well-man- (8-count average size). Yield 18,000 per acre) and constant aged experimental ponds. There- equals the number harvested per pond aeration. At this density the fore, farm-level production is acre multiplied by the average feeding rate is 2,500 to 3,000 usually inferior to production at size. pounds per acre and commercial experiment stations. yields typically range from 400 to Intensive stocking in experimen- 800 pounds per acre per year. Tables 1 and 2 summarize pro- tal ponds has often produced duction data from commercial yields of more than 2,000 pounds Some producers practice intensive and experimental sources, per acre when artificial sub- stocking of more than 18,000 per respectively, for several states. In strates were used (Table 2). acre. Feeding rates for intensive both tables, production has been These yields offset the high pro- stocking are 5,000 to 6,000 pounds segregated by stocking density. duction costs and result in low per acre per year. Intensive pro- From Table 1, low stocking den- break-even prices. Intensive duction is usually done in ponds sities (8,000 to 10,000 per acre) stocking is less common in com- with artificial substrate formed of typically produce 200 to 700 mercial ponds, although yields plastic mesh (the same as a barrier pounds per acre, while experi- have exceeded 1,000 pounds per Table 1. Prawn production data from commercial farms in the United States. FCR stands for feed conversion ratio. Stocking density Average yield Survival range Average size State (number/acre) FCR (lb/acre) (average % survival) (number /lb) KY 8,000–10,000 Not available 225–700 (210) 25–32 (28) 12 KY 12,000–17,000 Not available 0-860 (580) 0–100 (56) 14 KY 19,000–22,000 Not available 330–1,292 (964) 23–66 (47) 10 IL 6,000–10,000 1.23:1 533–900 (638) Not available Not available IL 14,000–16,000 5.45:1a 120–800 (592) Not available Not available IL 20,000 2.55:1 300 a Not available Not available OH 15,789–16,204 17:1 139–546 15–46 (32) 13–20 OH 19,427 18:1a 229 a 41a 29 a MS 10,000–18,000 Not available 750–1,100 (775) (66) 10–12 a Only one data point. Table 2. Prawn production data from experimental ponds in the United States. Stocking density Average yield Average size State (number/acre) FCR (lb/acre) Average % survival (number /lb) KY 8,000 3.12:1 734 74 7 KY 16,000 2.85:1 913 79 14 KY a 22,000–25,000 2.53:1 2,274 88 11 MS 8,500 3.5:1 897 86 8 MS 15,800 2.5:1 986 82 14 TN b 16,000 Not available 910–1,057 80–85 13–14 TN 20,000–24,000 Not available 1,137–1,586 80–85 13–14 a These experiments used artificial substrates with a surface area equivalent to 50 percent of the pond bottom area. b Information obtained from the University of Tennessee (Hill et al., 2003). acre in some cases and been com- remove pollutants before prawns have a 3- to 5-year lifespan. parable to extensive and semi- are stocked. Catfish-type paddlewheel aerators intensive yields in other cases. (5- to 10-hp) are more expensive While the potential returns are Equipment ($3,000 to $6,000) and are usually high, the operating cost is also Equipment needed for prawn not used. high, making intensive stocking farming includes electric aera- Fixed costs less attractive to some small-scale tors, a 5-hp water pump, a feed producers.