SRAC Publication No. 2600

VI July 2002 PR

Opportunities and Constraints in Marine Farming

Jack M. Whetstone1, Gravil D. Treece2, Craig L. Browdy3 and Alvin D. Stokes4

Shrimp , the produc- The major aspects of shrimp mari- ly among . Most tropical tion of saltwater shrimp in culture are sourcing or obtaining shrimp are 0.00003937 inches impoundments and , origi- brood for production, (220 micrometers) in diameter. nated in Southeast where for maturation and reproduction of They hatch within 14 hours at centuries raised incidental , genetic selection, 28 oC (82.4 oF). The nauplius is the of wild shrimp in tidal and nauplii production, larval first larval stage and it is attracted ponds. The shrimp were not con- rearing, postlarval holding and to light. In natural settings, the sidered of great value. Time has sales, growout in ponds and race- shrimp postlarvae (PL) are carried changed this perspective, and ways, production of bait or edible by currents to the protection shrimp culture has grown into one shrimp, harvesting, processing, of , where they have a of the largest and most important and sales to a world market. diet rich in various sources of crops worldwide. All . They remain there until kinds of shrimp (coldwater and Life cycle the late juvenile or early adult warmwater) are highly desirable stage. now in a world market. Most Juveniles and adults migrate off- The growout phase in bays and coastal countries have a harvest shore, and in the stable environ- ponds generally takes 4 to 5 for shrimp, and about 100 ment of the ocean they mature, months (16 to 20 weeks), depend- of those catch enough to export. mate, and eggs in offshore ing on the environmental condi- More than 50 countries practice waters (Fig. 1). All but one species tions, species, and, in bays, the shrimp aquaculture. Shrimp cul- within the Family fol- timing of migration to offshore ture increased 300 percent from low this life cycle sequence, areas. 1975 to 1985, and 250 percent from although the sequences vary great- 1985 to 1995. If it increases 200 per- cent between 1995 and 2005, world shrimp culture production will be at 2.1 million metric tons (MT =1.1 Postlarvae Protozoea standard tons, 2,204.6 pounds or 1,000 kg). According to a report of Mysis the and Nauplius Organization of the United Marsh Nations, world production of Juvenile farmed shrimp reached 1,130,000 Bay MT of whole shrimp in 1999. () Postlarvae Adult 1 Clemson University Eggs 2Texas A & M University 3Marine Resources Research Institute, South Carolina Department of Natural Resources OPEN OCEAN 4Waddell Mariculture Research and Development Center, South Carolina Department of Natural Resoruces Figure 1. Penaeid shrimp life cycle. History of marine shrimp through the U.S. Department of females with ripe, egg-laden farming Agriculture and the U.S. ovaries (gravid females) are Department of Commerce/ brought from the for spawning In 1933 M. Fujinaga of initi- NOAA/Sea Grant Program. in captivity. The availability and ated research on cost of wild gravid females can The first attempts at commercial japonicus (previously known as fluctuate. Their use precludes in the U.S. japonicus) and opened the genetic selection and complicates occurred in the late 1960s and door to modern shrimp farming. efforts to control disease introduc- early 1970s, following the His work contributed largely to tion. Thus, to achieve better con- Ecuadorian industry’s lead based the initial development of the trol, technologies for captive matu- upon the culture of industry. In the 1930s, J.C. Pearson ration and reproduction have been vannamei and Litopenaeus described the eggs of some west- developed. This has allowed for stylirostris. The initial U.S. industry ern hemisphere penaeid shrimp the establishment of breeding pro- used native species of white, and the life histories of some grams for fast growing, specific brown and pink shrimp. U.S. American penaeids. This was an -free and/or resistant researchers found that non-native important step in understanding stocks. Captive maturation is shrimp from the Pacific of how to obtain desired results in achieved by placing broodstock in Central and were hatchery and growout procedures. large (13-foot, 4-m) diameter tanks easier to culture and more produc- Since adults migrate offshore to at densities of five to seven shrimp tive in ponds. Gradually, commer- the more stable and tem- per 10.7 square feet (1 m2). The cial producers in the U.S. concen- peratures of the ocean, where they most important parameters for trated on non-native species such mature and reproduce, commercial successful maturation of penaeid as L. vannamei, now the most pop- found that they had to shrimp are constant temperature, ular species cultured in the mimic natural conditions. , pH, light, and good nutri- Western Hemisphere. Hatcheries worked better with tion (Table 1). higher salinities and cleaner water, Significant early contributions Once the gravid female is ready to whereas growout worked best in from private industry in the U.S. spawn, it releases eggs into the the back bays and estuaries with came from Ralston Purina and water, fertilizing the eggs by lower salinities. Marifarms in Florida, and Dow simultaneous rupturing of the Chemical in . Texas now pro- In the 1940s and 1950s, Robert spermatophore. The eggs exit the duces more -raised shrimp Lunz at the Bears Bluff Laboratory ovipositors, located at the base of than any other state—approxi- in South Carolina continued the the third pair of walking legs, and mately 8 million pounds (3.63 mil- development of extensive shrimp sink. In non-grooved white shrimp lion kg) of heads-on shrimp in production. He flooded tidal the eggs brush back against the 2001. Florida has the largest hatch- impoundments when native spermatophore as the female is ery in the U.S. It can produce 180 shrimp populations were migrat- continuously swimming. If the million PL per month, but sends ing, controlled predators, and used female stops swimming, or her most of them to for water exchange to maintain dis- swimming is interrupted, the eggs growout. solved levels. His work may fall straight down and are not refined extensive shrimp farming. Once shrimp hatcheries began sup- likely to be fertilized. plying large quantities of shrimp Harry Cook and others at the Most cultured adult shrimp pro- to farmers, the production of farm- National Marine Service duce 150,000 to 200,000 eggs per raised shrimp expanded rapidly. laboratory in Galveston, Texas spawn, depending upon the size of Problems with disease and poor established the “Galveston the female. The larger species, such water quality in the early 1990s Technique” of culturing shrimp as , can produce slowed worldwide production for larvae, which helped to expand 700,000 to more than 1 million a few years. In recent years, pro- shrimp hatchery technology. eggs each spawn. After hatching, duction has been increasing Research on the culture of larval shrimp develop through several because of new disease control shrimp started there in 1959 as larval stages. The eggs hatch into protocols and water recirculation part of an investigation into the the first larval stage, called the and reuse technologies. life history of native shrimp in the nauplius. The microscopic nau- Gulf of . Harry Cook pub- plius larvae are planktonic and lished a generic key to the zoeal, Shrimp hatcheries feed on their sacs for 48 mysis, and postlarval (PL) stages The hatchery cycle begins with hours. The nauplius stage is the of littoral Penaeidae of the north- broodstock. In many hatcheries, best larval stage to or trans- west Gulf of Mexico in 1965. Other groups also worked on larval rear- ing of penaeids in the U.S., mainly Table 1. Parameters for tropical shrimp maturation and allowable in Texas. The Texas Parks and ranges per 24 hours. Wildlife Department and some of the universities published works Salinity Temperature pH Light D.O. on the subject very early. A signifi- 27-36 ppt +/- 0.5 27-29 oC +/- 2 o 7.8 +/- 0.2 14 L, 10 D 5 ppm + cant aquaculture research and o development effort continues (80.5-84.2 F) port. Starting at about hour 36 after hatch, microscopic, single-celled and later other minute forms of zooplanktonic microcrustaceans (usually freshly hatched shrimp, Artemia nauplii) are fed to specific larval stages. The larvae develop through three zoea stages and three mysis stages before metamorphosing into a form more closely resembling a typical shrimp or postlarva. Development through larval stages takes 9 to 11 days from hatching (at 28 oC or 82.4 oF). Some hatcheries shorten the larval time in the hatchery by raising the temperature; however, care must be taken because bacterial prob- lems develop faster at the higher temperatures. The most successful Figure 2. Larval rearing facility. hatcheries control and At the high stocking densities typi- other diseases through disinfection sive according to stocking density cal of intensive culture systems, and other preventive measures. and associated management para- meters. Large ponds or impound- natural food organisms do not One of the most important aspects ments may be stocked at low den- supply enough nutrition and the of the location and functionality of sities, producing crops with little must provide a nutritional- the shrimp hatchery is water quali- or no supplemental feed and rely- ly complete ration. Feeding effi- ty. Almost all hatcheries require ing on wind or water exchange to ciency is crucial, as high quality oceanic quality water on a 24-hour manage water quality. Semi- feeds are very expensive compared basis. Shrimp hatcheries require intensive ponds are normally to the supplemental feeds used in relatively small tracts of land and somewhat smaller, are stocked at semi-intensive culture. Farmers are operated in a labor-intensive higher densities, and use fertiliza- routinely pay $0.45 per pound manner. See Figure 2 for a larval tion, water exchange and supple- ($1.00/kg) or more for intensive rearing facility. mental feeding to increase yields. culture feed. This represents 60 to The most technologically advanced 70 percent of the cost of produc- Nurseries culture systems are intensive and tion. To achieve good feed conver- were developed in countries such sion, feeding trays are often used Nursery ponds are smaller ponds as Japan, and the U.S., to measure consumption continu- or intensive raceways that serve as where wild PL are not readily ously. an intermediate phase between the available and where land and labor In addition to the expense of extra hatchery and the growout ponds. are expensive. To justify the high Nurseries can be used to increase feed, intensive farmers incur the input costs and to maximize cost of controlling water quality. shrimp size for stocking growout returns, high yields per unit area ponds. They also make more effi- The pond bottom is easily fouled and labor are required. Yields from by the heavy organic load from cient use of the growout produc- intensive and super-intensive tion area, allow the growing season high feeding rates. These costs are ponds can range from 3,000 to part of the capital and operating to be extended in temperate and more than 20,000 pounds per acre subtropical climates, and make it expenses to build smaller, more per (1,361 kg to more than manageable ponds, install pumps possible to evaluate shrimp and 9,072 kg per 0.4 ha). eliminate substandard stocks and wells to allow for high rates of before stocking growout ponds. The growout ponds are used to produce marketable shrimp. Not Table 2. Shrimp growout comparison table. all use the nursery phase. Extensive Semi-intensive Intensive Many farms stock PL, either from the wild (countries other than the Stocking density 1-10 10-30 >30 U.S.) or from the hatchery, directly (Shrimp/m2) to the growout pond. Whether or (Shrimp/10.7 ft2) not a nursery is used, an acclima- Pond size 5-20 1-10 <0.5 tion period is normally used to (hectare) prepare PL for farm conditions. Aeration None 0-2.5 >2.5 (hp/ha) Growout systems Production rates 100-1,000 1,000-3,000 >3,000 (kg/ha/crop) Growout systems are considered ( lbs/ac/crop) extensive, semi-intensive or inten- ˜ water exchange or recirculation, use in the waters of the U.S. The duction must be done on a large and use of mechanical devices to availability of native PL for stock- scale to be profitable where land, circulate and aerate the water. ing is a problem in developing the labor, energy and capital costs are industry. Native species do not high. Super-intensive culture can The cost per pound to produce grow as quickly as non-native be coupled with the latest tech- shrimp generally rises with higher species. There is a finite market for nologies in water reuse to expand culture intensity, because of live bait shrimp and harvest and production to areas other than increased stocking densities, feed- post-harvest handling of a live expensive coastal land. Further- ing rates and water quality man- product is much more difficult. To more, these systems can be agement efforts. The most cost- date there are no large, sustainable, designed to alleviate the environ- effective production strategy for economically viable bait shrimp mental concerns associated with any particular farmer depends on producers in the U.S. shrimp culture. Promising research the size of the initial capital invest- and small-scale production suggest ment, the cost of available inputs, Impoundment production that these technologies may be suc- (feed, PL, labor, fuel, power, etc.), cessful on a larger scale in the near the availability of suitable sites, Coastal impoundments future. However, super-intensive and the potential cost savings are used to produce penaeid systems rely on high market prices from economies of scale relative to shrimp in extensive culture sys- and, thus, have greater economic the total area under culture. tems. They use natural stocking or risk. hatchery reared stock. With only Water quality natural stocking, yields are low Inland and (<100 pounds per acre, <100 Maintaining good water quality in kg/ha) on large acreages. Stocking freshwater production ponds is crucial for success. Table hatchery-reared shrimp and pro- 3 is a compilation of water charac- Inland farming of marine shrimp, viding supplemental feed increase using brackish water, is being done teristics for shrimp culture from production in wetland impound- various sources. successfully on a commercial scale ments to 1,000 pounds per acre in Texas, Alabama and Arizona; (˜1,000 kg/ha) in certain commer- however, specific water quality Harvesting cial management regimens. To be parameters of saline groundwater economically viable, such opera- Three crops per year are possible are of extreme importance in the tions must use existing impound- in a warm climate, although most selection of successful sites. Florida ments, few farms in the tropics average 2.6 is also attempting the commercial of which are suitable for shrimp crops on a year-round basis. culture of marine shrimp using production. Production levels during the cool- “fresher” ground waters. The er months will not be as high, and brackish water operations have time is needed to treat pond bot- Super-intensive raceways operated successfully for several toms between crops. Southern U.S. The production of shrimp in years and expanded. In Arizona, shrimp farms average 3,500 to super-intensive systems extremely low salinity effluents 6,400 pounds per acre per crop (Fig. 4) has many potential advan- from ponds are used in integrated (1,588 kg to 2,903 kg per 0.4 ha) of tages. These systems make temper- systems as a rich source of water heads-on shrimp, which generally ature control easier, making them for irrigating winter wheat and fall into the 26- to 30- or 31- to 35- applicable in subtropical and tem- table olives. Saline effluent in other count tail sizes (number of shrimp perate zones. Super-intensive pro- states is used in either on-site hold- per pound). Most farms have one crop per year. Harvests are gener- ally conducted with an automated harvester. The harvester (Fig. 3) is usually mounted on a trailer and can be moved from pond to pond. Magic Valley Heliarc makes one of the most commonly used “fish pumps” for harvesting shrimp.

Other production methods Bait shrimp A number of research and devel- opment projects and commercial attempts to raise shrimp for bait have occurred in the U.S., and some continue today. Research has demonstrated the potential for bait shrimp culture, but due to regula- tions the industry is limited to producing only native shrimp for Figure 3. Shrimp harvester. Table 3. Water characteristics for shrimp culture. (All parameters in ppm [mg/L] unless noted otherwise). Variable Form in water Desired concentration Notes - 1 Boron Borate (H3BO3, H2BO3 ) 0.05 –1 See Cadmium (Cd) <0.1 Calcium Calcium ion (Ca2+) 100 - 500 Carbon dioxide Dissolved CO2 Gas 1 - 10 Chloride Chloride ion (Cl-) 2,000 - 20,000 Copper ion (Cu2+) <0.0005 See 1 Total Copper 0.0005 - 0.01 Iron See 1 Ferrous iron (Fe2+)0 Ferric iron (Fe3+) Trace Total iron 0.05 - 0.5 Magnesium Magnesium ion (Mg2+) 100 - 1,500 Manganese Manganese ion(Mn2+)0 Manganese dioxide (MnO2) Trace Total manganese 0.05 - 0.2 Molybdenum Molybdate (MoO3) Trace Dissolved N2 Gas Molecular nitrogen (N2) Saturation or less + Ammonium (NH4 ) 0.2 - 2 Ammonia (NH3) <0.1 Nitrate (NO -) 0.2 - 10 3- Nitrite (NO2 ) <0.23 2 Oxygen Dissolved O2 Gas 5 - 15 See pH H+[-log(H+)=pH] pH 7 - 9 See 3 Potassium Potassium ion (K+) 100 - 400 Salinity 5,000 - 35,000 See 4 Sodium Sodium (Na+) 2,000 - 11,000 Sulfur 2- Sulfate (SO4 ) 500 - 3,000 Hydrogen Sulfide <0.02 (preferably not detectable) Suspended Solids <100 Temperature 26-29 oC (78.8-84.2 oF) See 5 See 6 Zinc ion (Zn2+) <0.01 Total zinc 0.01 - 0.05 Notes: 1 The desirable ranges for these substances are poorly understood. The values listed as the desired concentrations are actually the usual con- centrations of these trace metals in surface waters. 2 O2 for growth, 2-3 ppm minimum. 3 pH directly influences shrimp (pH of 4 = acid death point; 4-5 = no reproduction; 4-6 = slow growth; 6-9 = best growth; 9-11 = slow growth; 11 = alkaline death point). 4 Salinity is normally referred to in parts per thousand or ppt (5,000 - 35,000 ppm = 5 - 35 ppt). 35 ppt is generally considered a normal salini- ty for open ocean water. Some shrimp can grow in salinities outside these ranges. 5 Temperature for tropical shrimp. For growth, 23-25 oC (73.4-77 oF) minimum, and 33-34 oC (91.4-93.2 oF) maximum. 6 Turbidity (Goal is Secchi disk reading of 25-40 cm (10-16 in.) and water color of yellowish-brown). Marketing Shrimp are generally sold to the processing plant. The average farm-gate price in Texas in 2000 was $3.40 per pound ($7.71/kg) for head-on shrimp (18-gram or 25-count = 25 shrimp per pound). One farm has its own processing plant that de-heads the product and individually quick freezes (IQF) the tails in 5-pound (2.268- kg) clear plastic freezer bags. This product sells for about $5.90 per pound ($13.38/kg) at the cold storage facility, which is also owned by the farmer. Most farms either sell to the plant or have the processing plant de-head the prod- uct, blast-freeze the tails, pack them in 5-pound (2.2-kg) waxed boxes with the plant’s or the farm’s label on the box, and hold the shrimp for 1 month as part of Figure 4. Super-intensive raceway system for shrimp. the processing cost. There are a number of wholesalers ing ponds or reused in adjacent cent of a shrimp’s weight is in the and seafood buyers who purchase ponds. In inland systems, head. Production in ponds often the product and pass the shrimp saline effluent will remain a major ranges from 2,000 to 8,000 pounds through the U.S. marketing chan- issue as more restrictions on aqua- per acre per crop in the U.S., with nels. Shrimp prices are available culture effluent evolve. an average crop of 3,500 pounds on the internet at per acre. http://www.st.nmfs.gov/st1/ market_news/doc45.txt. Economics of producing A 20 percent profit margin is con- shrimp in ponds sidered good in this high-risk Major constraints industry. Profit margins have been Shrimp are produced in ponds, narrowing because of rising feed, Of all natural products, seafood raceways and tanks. Production labor and fuel costs and new dis- contributes more to the U.S. trade costs vary from $2.50 to $5.00 per charge regulations have hurt the deficit than any other product pound. Feed, larvae and processing farms because more money is except oil. When all products are are the three highest variable costs. needed to install new recirculation considered, seafood is fourth after It generally takes 2 pounds (0.91 pumps, etc. Market prices for oil, automobiles and electronics. kg) of feed to produce 1 pound shrimp were down in 2001, which Growing populations along the (0.45 kg) of shrimp. The main eco- also contributes to the risky nature are placing extra burdens on nomic problems with culturing of the industry. coastal environments. Seafood shrimp in the U.S. are: safety is an issue as environmental Costs for a pilot shrimp farm in degradation continues. The availability of low-cost, high south Texas are shown in Table 4. quality feed, Hazard Analysis Critical Control The farm consists of four 5-acre (2- Point program (HACCP) begun in short growing season (one crop ha) ponds, with a December, 1997, placed additional only in some areas because of attached to each pond and one controls upon the seafood industry temperatures), common 14.8-acre (6-ha) construct- (see http://vm.cfsan.fda.gov/ ed wetland. A total of 50 acres is ~dms/haccp-2a.html for more infor- high land, labor and operating needed for this facility. The facility (power, etc.) costs, mation). With limited entries, by- is now in operation and was catch controversies, and turtle-free foreign competition, and designed to treat water on-site and and dolphin-free industry require- to discharge water only during price fluctuations. ments, the wild-caught seafood harvest. The farm takes in has little opportunity to Shrimp producers generally con- only to fill ponds and offset evapo- expand. New environmental regu- tract with a processing plant to ice, ration and other water loss, and lations on our coasts also constrain de-head, grade, pack, freeze in the facility is capable of producing aquaculture. plate freezer, and keep shrimp for 36 MT of shrimp per year (approx- imately 4,000 pounds per acre). 1 month in cold storage. Processors Disease risks charge an average of $0.63 per The average construction cost for pound ($1.39/kg). About 40 per- the 50-acre (20-ha) facility was Shrimp diseases have also con- $9,191 per acre ($22,978/ha). strained the industry. Shrimp Table 4. Costs for a pilot shrimp farm in Texas. Price in US $ Contractual Construction management, equipment operator & rental 20,045 Earth moving 72,982 Electricity establishment (includes electricity to aerators) 25,000 Fencing (1,500 meters or 5,000 feet installed) 10,815 , repairs and maintenance, dues, water analysis, misc. 6,000 Legal fees (permitting, etc.) 50,000 Supplies Wetland vegetation, truck fuel, grass seed, tools, misc. 18,400 Pipe, lumber, hardware 20,073 Equipment Land (50 acres @ $1,500/acre or 20 @ $3,750/ha) 75,000 Pumps 5,000 Feed equipment: pond feeder, bulk bin (8-ton) 10,770 Aerators, controllers and wire (60 @ 2 hp each) ($476 each) 28,565 Emergency aerator 4,449 Tractor (used, 140 hp), truck (used, 3/4-ton, 4wd) 25,000 Electrical generator (pto driven, 50 kva) 5,000 Drains, harvest basins 7,953 Scraper blade, mower 4,000 Screens, nets, pl acclimation equipment 3,500 Trailer & furniture (office, storage & occasional housing) 11,000 Water quality lab equipment 8,500 Repairs, contingencies, misc. 11,000 Personnel On-farm labor, consultants 36,500 Total costs $459,552

Source: Ronald Rosati, Texas A&M University—Kingsville. , in particular, can devastate Weather object to the introduction of non- shrimp in crowded culture condi- native species and farmers must be tions. But genetic selection pro- Weather in the U.S. also constrains ever mindful of the possible grams such as the one conducted shrimp aquaculture. Cold weather, restriction on the use of non-native by the USDA’s Marine Shrimp drought and hurricanes are the species if they escape and ecologi- Farming Program have made primary concerns. In October 2000, cal problems develop. progress in producing shrimp extreme cold contributed to the stocks that are more resistant to loss of 1.5 million pounds (680,000 Discharges diseases. For example, the USDA kg) of shrimp on Texas shrimp has developed genetically farms. The climate allows one long There are very strict regulations for improved stocks that are resistant crop or two short crops during the shrimp farm discharges. Stricter to the . summer months (generally from environmental regulations and the Genetically superior shrimp are April to October). desire to control the spread of held in quarantine in and shrimp diseases have forced some their offspring are sent to U.S. Non-native introductions of the farms to recirculate water. hatcheries. However, as more Based in part on research at South Litopenaeus vannamei is the most research on shrimp diseases has Carolina’s Waddell Mariculture common exotic or non-native been conducted, more diseases Center, farmers have learned to shrimp used in the U.S. Some have been identified. produce shrimp using far less releases of these shrimp have measures and regulatory con- water than ever thought possible. occurred at harvest in the past, but straints on PL shrimp for stocking One Texas farm is producing more strict regulations now prevent reduce the possibility of introduc- than 1.4 million pounds (637,435 their accidental release into the ing diseases, but if broodstock kg) of shrimp on 345 acres (139 ha) environment. Pond discharges come from surface water sources, or about 4,000 pounds per acre must be double- or triple-screened the possibility is always real. (4,481 kg/ha) in a semi-closed sys- to prevent the escape of non-native tem. The farm cut its water use shrimp into the natural environ- from 4,500 gallons per pound ment. A number of groups still (37,561 L/kg) of shrimp produced in 1994 to 300 gallons per pound reviewing aquaculture effluents to progress. Shrimp farming, like (2,504 L/kg) in 1998-2001. Most of with the goal of improving dis- any new production indus- the water is used to fill the ponds charge regulations in the aquacul- try, has high risks. U.S. shrimp and offset evaporation. Most farms ture industry. Any new regulations farming also must compete with a also have cut stocking density are to be based on scientific data highly productive international from 50 to 36 shrimp per 10.7 and directed at implementing eco- industry and with other develop- square feet and increased aeration nomically viable, technology-based ment interests for valuable coastal from 8 to 10 hp per acre (20 to 25 solutions for improving the quality sites. hp/ha). Some farms use as much of aquaculture effluent. The regu- as 16 hp per acre (40 hp/ha) if they lations, if changed, will certainly Suggested reading recirculate water through wet- increase the cost of production and lands. Other farms have developed restrict the development of the Boyd, C.E. 2001. Inland Shrimp adjacent ponds, which industry. Farming and the Environment. serve as settling ponds and act as World Aquaculture 32 (1): 10-12. natural filters while producing a Hatchery constraints Boyd, C.E. and C.S. Tucker. 1998. secondary crop. Some farms have Pond Aquaculture Water widened and deepened their dis- Almost all marine shrimp farms in Quality Management. Kluwer charge canals and aerate them. As the U.S. stock non-native Academic Publishers, Boston, a result of these changes, the Total Litopenaeus vannemei because they Mass. Suspended Solids (TSS) discharged grow better and have better feed on intensive farms dropped from conversion than native species. Browdy, C.L. and D.E. Jory, 2001. 3.6 pounds (1.6 kg) per pound of Only a few shrimp hatcheries meet The New Wave, Proceedings of shrimp in 1994 to 1 pound (0.45 the USDA the Special Session on kg) per 20 pounds (9kg) of shrimp Consortium guidelines as sources Sustainable Shrimp Farming. in 1998. Over the same time peri- of non-native PL for shrimp stock- World Aquaculture Society, od, farms reduced: ing, so there has often been a Baton Rouge, LA. shortage of PL during the brief ammonia from 0.05 pounds per U.S. stocking season. When PL are Treece, G.D. and M.E. Yates, 2000. pound of shrimp to 1 pound for in short supply, some farms can Laboratory Manual for the every 2,500 pounds of shrimp stock only at certain densities and Culture of Penaeid Shrimp (0.45 kg ammonia per 1,125 kg on certain stocking dates. Any loss Larvae. TAMU Sea Grant of shrimp); of production from the few hatch- Publication #88-202(R). carbonaceous biochemical oxy- eries that exist can make a tight PL Villalon, J.R. 1991. Practical gen demand from 0.1 to 0.17 supply even more restrictive to the Manual for Semi-intensive pound (0.045 to 0.008 kg) per industry. Commercial Production of pound of shrimp to 1 pound Marine Shrimp. TAMU Sea (0.45 kg) for every 100 pounds Conclusions Grant Publication #91-501. Hard (45 kg) of shrimp copy is out of print but manual Opportunities for marine shrimp can be downloaded free of These farms have also maintained aquaculture in the U.S. are expand- charge from the National Sea production at more than 4,000 ing, but there are many constraints Grant Office pounds per acre (4,481 kg/ha) of and the risks are high. In states Web site at shrimp since 1994. The develop- where the stocking of non-native http://nsgl.gso.uri.edu/tamu/tamuh ment of environmentally sensitive shrimp is allowed, the industry 91001/tamuh91001index.htm. management techniques is ensur- has grown. Regulations on non- ing the future of sustainable native introductions and discharge Wyban, J. A. and J. N. Sweeney. shrimp farming in U.S. coastal are a burden to the industry, but 1991. The Oceanic Institute areas. In 2000, the U.S. Environ- through research and Extension Shrimp Manual: Intensive mental Protection Agency began programs the industry continues Shrimp Production Technology. The Oceanic Institute, P. O. Box 25280, Honolulu, Hawaii 96825.

SRAC fact sheets are reviewed annually by the Publications, Videos and Computer Software Steering Committee. Fact sheets are revised as new knowledge becomes available. Fact sheets that have not been revised are considered to reflect the current state of knowledge.

The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 00-38500-8992 from the Department of Agriculture, Cooperative State Research, , and Extension Service.