Shrimp mariculture, the produc-tion of saltwater shrimp inimpoundments and ponds, origi-nated in Southeast Asia where forcenturies farmers raised incidentalcrops of wild shrimp in tidal fishponds. The shrimp were not con-sidered of great value. Time haschanged this perspective, andshrimp culture has grown into oneof the largest and most importantaquaculture crops worldwide. Allkinds of shrimp (coldwater andwarmwater) are highly desirablenow in a world market. Mostcoastal countries have a harvestindustry for shrimp, and about 100of those catch enough to export.More than 50 countries practiceshrimp aquaculture. Shrimp cul-ture increased 300 percent from1975 to 1985, and 250 percent from1985 to 1995. If it increases 200 per-cent between 1995 and 2005, worldshrimp culture production will beat 2.1 million metric tons (MT =1.1standard tons, 2,204.6 pounds or1,000 kg). According to a report ofthe Food and AgricultureOrganization of the UnitedNations, world production offarmed shrimp reached 1,130,000MT of whole shrimp in 1999.

The major aspects of shrimp mari-culture are sourcing or obtainingbrood for hatchery production,maturation and reproduction ofbroodstock, genetic selection, eggand nauplii production, larvalrearing, postlarval holding andsales, growout in ponds and race-ways, production of bait or edibleshrimp, harvesting, processing,and sales to a world market.

Life cycleJuveniles and adults migrate off-shore, and in the stable environ-ment of the ocean they mature,mate, and spawn eggs in offshorewaters (Fig. 1). All but one specieswithin the Family Penaeidae fol-low this life cycle sequence,although the sequences vary great-

ly among species. Most tropicalshrimp eggs are 0.00003937 inches(220 micrometers) in diameter.They hatch within 14 hours at 28 oC (82.4 oF). The nauplius is thefirst larval stage and it is attractedto light. In natural settings, theshrimp postlarvae (PL) are carriedby ocean currents to the protectionof estuaries, where they have adiet rich in various sources ofnutrition. They remain there untilthe late juvenile or early adultstage.

The growout phase in bays andponds generally takes 4 to 5months (16 to 20 weeks), depend-ing on the environmental condi-tions, species, and, in bays, thetiming of migration to offshoreareas.

VIPRJuly 2002

SRAC Publication No. 2600

Opportunities and Constraints in MarineShrimp Farming

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

1Clemson University2Texas A & M University3Marine Resources Research Institute, South

Carolina Department of Natural Resources4Waddell Mariculture Research and

Development Center, South CarolinaDepartment of Natural Resoruces Figure 1. Penaeid shrimp life cycle.

Postlarvae

Juvenile

Postlarvae

Bay(estuary)

Marsh

Mysis

Adult

Eggs

OPEN OCEAN

Nauplius

Protozoea

History of marine shrimpfarming In 1933 M. Fujinaga of Japan initi-ated research on Marsupenaeusjaponicus (previously known asPenaeus japonicus) and opened thedoor to modern shrimp farming.His work contributed largely tothe initial development of theindustry. In the 1930s, J.C. Pearsondescribed the eggs of some west-ern hemisphere penaeid shrimpand the life histories of someAmerican penaeids. This was animportant step in understandinghow to obtain desired results inhatchery and growout procedures.Since adults migrate offshore tothe more stable salinities and tem-peratures of the ocean, where theymature and reproduce, commercialhatcheries found that they had tomimic natural conditions.Hatcheries worked better withhigher salinities and cleaner water,whereas growout worked best inthe back bays and estuaries withlower salinities.

In the 1940s and 1950s, RobertLunz at the Bears Bluff Laboratoryin South Carolina continued thedevelopment of extensive shrimpproduction. He flooded tidalimpoundments when nativeshrimp populations were migrat-ing, controlled predators, and usedwater exchange to maintain dis-solved oxygen levels. His workrefined extensive shrimp farming.

Harry Cook and others at theNational Marine Fisheries Servicelaboratory in Galveston, Texasestablished the “GalvestonTechnique” of culturing shrimplarvae, which helped to expandshrimp hatchery technology.Research on the culture of larvalshrimp started there in 1959 aspart of an investigation into thelife history of native shrimp in theGulf of Mexico. Harry Cook pub-lished a generic key to the zoeal,mysis, and postlarval (PL) stagesof littoral Penaeidae of the north-west Gulf of Mexico in 1965. Othergroups also worked on larval rear-ing of penaeids in the U.S., mainlyin Texas. The Texas Parks andWildlife Department and some ofthe universities published workson the subject very early. A signifi-cant aquaculture research anddevelopment effort continues

through the U.S. Department ofAgriculture and the U.S.Department of Commerce/NOAA/Sea Grant Program.

The first attempts at commercialshrimp farming in the U.S.occurred in the late 1960s andearly 1970s, following theEcuadorian industry’s lead basedupon the culture of Litopenaeusvannamei and Litopenaeusstylirostris. The initial U.S. industryused native species of white,brown and pink shrimp. U.S.researchers found that non-nativeshrimp from the Pacific coast ofCentral and South America wereeasier to culture and more produc-tive in ponds. Gradually, commer-cial producers in the U.S. concen-trated on non-native species suchas L. vannamei, now the most pop-ular species cultured in theWestern Hemisphere.

Significant early contributionsfrom private industry in the U.S.came from Ralston Purina andMarifarms in Florida, and DowChemical in Texas. Texas now pro-duces more farm-raised shrimpthan any other state—approxi-mately 8 million pounds (3.63 mil-lion kg) of heads-on shrimp in2001. Florida has the largest hatch-ery in the U.S. It can produce 180million PL per month, but sendsmost of them to Honduras forgrowout.

Once shrimp hatcheries began sup-plying large quantities of shrimpto farmers, the production of farm-raised shrimp expanded rapidly.Problems with disease and poorwater quality in the early 1990sslowed worldwide production fora few years. In recent years, pro-duction has been increasingbecause of new disease controlprotocols and water recirculationand reuse technologies.

Shrimp hatcheriesThe hatchery cycle begins withbroodstock. In many hatcheries,

females with ripe, egg-ladenovaries (gravid females) arebrought from the sea for spawningin captivity. The availability andcost of wild gravid females canfluctuate. Their use precludesgenetic selection and complicatesefforts to control disease introduc-tion. Thus, to achieve better con-trol, technologies for captive matu-ration and reproduction have beendeveloped. This has allowed forthe establishment of breeding pro-grams for fast growing, specificpathogen-free and/or resistantstocks. Captive maturation isachieved by placing broodstock inlarge (13-foot, 4-m) diameter tanksat densities of five to seven shrimpper 10.7 square feet (1 m2). Themost important parameters forsuccessful maturation of penaeidshrimp are constant temperature,salinity, pH, light, and good nutri-tion (Table 1).

Once the gravid female is ready tospawn, it releases eggs into thewater, fertilizing the eggs bysimultaneous rupturing of thespermatophore. The eggs exit theovipositors, located at the base ofthe third pair of walking legs, andsink. In non-grooved white shrimpthe eggs brush back against thespermatophore as the female iscontinuously swimming. If thefemale stops swimming, or herswimming is interrupted, the eggsmay fall straight down and are notlikely to be fertilized.

Most cultured adult shrimp pro-duce 150,000 to 200,000 eggs perspawn, depending upon the size ofthe female. The larger species, suchas Penaeus monodon, can produce700,000 to more than 1 millioneggs each spawn. After hatching,shrimp develop through severallarval stages. The eggs hatch intothe first larval stage, called thenauplius. The microscopic nau-plius larvae are planktonic andfeed on their yolk sacs for 48hours. The nauplius stage is thebest larval stage to ship or trans-

Table 1. Parameters for tropical shrimp maturation and allowableranges per 24 hours.

Salinity Temperature pH Light D.O.

27-36 ppt +/- 0.5 27-29 oC +/- 2 o 7.8 +/- 0.2 14 L, 10 D 5 ppm +

(80.5-84.2 oF)

port. Starting at about hour 36 afterhatch, microscopic, single-celledalgae and later other minute formsof zooplanktonic microcrustaceans(usually freshly hatched brineshrimp, Artemia nauplii) are fed tospecific larval stages. The larvaedevelop through three zoea stagesand three mysis stages beforemetamorphosing into a form moreclosely resembling a typical shrimpor postlarva. Development throughlarval stages takes 9 to 11 daysfrom hatching (at 28 oC or 82.4 oF).Some hatcheries shorten the larvaltime in the hatchery by raising thetemperature; however, care mustbe taken because bacterial prob-lems develop faster at the highertemperatures. The most successfulhatcheries control bacteria andother diseases through disinfectionand other preventive measures.

One of the most important aspectsof the location and functionality ofthe shrimp hatchery is water quali-ty. Almost all hatcheries requireoceanic quality water on a 24-hourbasis. Shrimp hatcheries requirerelatively small tracts of land andare operated in a labor-intensivemanner. See Figure 2 for a larvalrearing facility.

NurseriesNursery ponds are smaller pondsor intensive raceways that serve asan intermediate phase between thehatchery and the growout ponds.Nurseries can be used to increaseshrimp size for stocking growoutponds. They also make more effi-cient use of the growout produc-tion area, allow the growing seasonto be extended in temperate andsubtropical climates, and make itpossible to evaluate shrimp andeliminate substandard stocksbefore stocking growout ponds.The growout ponds are used toproduce marketable shrimp. Notall farms use the nursery phase.Many farms stock PL, either fromthe wild (countries other than theU.S.) or from the hatchery, directlyto the growout pond. Whether ornot a nursery is used, an acclima-tion period is normally used toprepare PL for farm conditions.

Growout systemsGrowout systems are consideredextensive, semi-intensive or inten-

sive according to stocking densityand associated management para-meters. Large ponds or impound-ments may be stocked at low den-sities, producing crops with littleor no supplemental feed and rely-ing on wind or water exchange tomanage pond water quality. Semi-intensive ponds are normallysomewhat smaller, are stocked athigher densities, and use fertiliza-tion, water exchange and supple-mental feeding to increase yields.The most technologically advancedculture systems are intensive andwere developed in countries suchas Japan, Taiwan and the U.S.,where wild PL are not readilyavailable and where land and laborare expensive. To justify the highinput costs and to maximizereturns, high yields per unit areaand labor are required. Yields fromintensive and super-intensiveponds can range from 3,000 tomore than 20,000 pounds per acreper crop (1,361 kg to more than9,072 kg per 0.4 ha).

At the high stocking densities typi-cal of intensive culture systems,natural food organisms do notsupply enough nutrition and thefarmer must provide a nutritional-ly complete ration. Feeding effi-ciency is crucial, as high qualityfeeds are very expensive comparedto the supplemental feeds used insemi-intensive culture. Farmersroutinely pay $0.45 per pound($1.00/kg) or more for intensiveculture feed. This represents 60 to70 percent of the cost of produc-tion. To achieve good feed conver-sion, feeding trays are often usedto measure consumption continu-ously.

In addition to the expense of extrafeed, intensive farmers incur thecost of controlling water quality.The pond bottom is easily fouledby the heavy organic load fromhigh feeding rates. These costs arepart of the capital and operatingexpenses to build smaller, moremanageable ponds, install pumpsand wells to allow for high rates of

Table 2. Shrimp growout comparison table.

Extensive Semi-intensive Intensive

Stocking density 1-10 10-30 >30(Shrimp/m2)(Shrimp/10.7 ft2)Pond size 5-20 1-10 <0.5(hectare)Aeration None 0-2.5 >2.5(hp/ha)Production rates 100-1,000 1,000-3,000 >3,000(kg/ha/crop)(˜lbs/ac/crop)

Figure 2. Larval rearing facility.

duction must be done on a largescale to be profitable where land,labor, energy and capital costs arehigh. Super-intensive culture canbe coupled with the latest tech-nologies in water reuse to expandproduction to areas other thanexpensive coastal land. Further-more, these systems can bedesigned to alleviate the environ-mental concerns associated withshrimp culture. Promising researchand small-scale production suggestthat these technologies may be suc-cessful on a larger scale in the nearfuture. However, super-intensivesystems rely on high market pricesand, thus, have greater economicrisk.

Inland brackish water andfreshwater productionInland farming of marine shrimp,using brackish water, is being donesuccessfully on a commercial scalein Texas, Alabama and Arizona;however, specific water qualityparameters of saline groundwaterare of extreme importance in theselection of successful sites. Floridais also attempting the commercialculture of marine shrimp using“fresher” ground waters. Thebrackish water operations haveoperated successfully for severalyears and expanded. In Arizona,extremely low salinity effluentsfrom ponds are used in integratedsystems as a rich source of waterfor irrigating winter wheat andtable olives. Saline effluent in otherstates is used in either on-site hold-

water exchange or recirculation,and use of mechanical devices tocirculate and aerate the water.

The cost per pound to produceshrimp generally rises with higherculture intensity, because ofincreased stocking densities, feed-ing rates and water quality man-agement efforts. The most cost-effective production strategy forany particular farmer depends onthe size of the initial capital invest-ment, the cost of available inputs,(feed, PL, labor, fuel, power, etc.),the availability of suitable sites,and the potential cost savingsfrom economies of scale relative tothe total area under culture.

Water qualityMaintaining good water quality inponds is crucial for success. Table3 is a compilation of water charac-teristics for shrimp culture fromvarious sources.

Harvesting Three crops per year are possiblein a warm climate, although mostfarms in the tropics average 2.6crops on a year-round basis.Production levels during the cool-er months will not be as high, andtime is needed to treat pond bot-toms between crops. Southern U.S.shrimp farms average 3,500 to6,400 pounds per acre per crop(1,588 kg to 2,903 kg per 0.4 ha) ofheads-on shrimp, which generallyfall into the 26- to 30- or 31- to 35-count tail sizes (number of shrimpper pound). Most farms have onecrop per year. Harvests are gener-ally conducted with an automatedharvester. The harvester (Fig. 3) isusually mounted on a trailer andcan be moved from pond to pond.Magic Valley Heliarc makes one ofthe most commonly used “fishpumps” for harvesting shrimp.

Other production methods

Bait shrimp

A number of research and devel-opment projects and commercialattempts to raise shrimp for baithave occurred in the U.S., andsome continue today. Research hasdemonstrated the potential for baitshrimp culture, but due to regula-tions the industry is limited toproducing only native shrimp for

use in the waters of the U.S. Theavailability of native PL for stock-ing is a problem in developing theindustry. Native species do notgrow as quickly as non-nativespecies. There is a finite market forlive bait shrimp and harvest andpost-harvest handling of a liveproduct is much more difficult. Todate there are no large, sustainable,economically viable bait shrimpproducers in the U.S.

Impoundment production

Coastal wetland impoundmentsare used to produce penaeidshrimp in extensive culture sys-tems. They use natural stocking orhatchery reared stock. With onlynatural stocking, yields are low(<100 pounds per acre, <100kg/ha) on large acreages. Stockinghatchery-reared shrimp and pro-viding supplemental feed increaseproduction in wetland impound-ments to 1,000 pounds per acre(˜1,000 kg/ha) in certain commer-cial management regimens. To beeconomically viable, such opera-tions must use existing impound-ments, few of which are suitable for shrimpproduction.

Super-intensive raceways

The production of shrimp insuper-intensive raceway systems(Fig. 4) has many potential advan-tages. These systems make temper-ature control easier, making themapplicable in subtropical and tem-perate zones. Super-intensive pro-

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

Boron Borate (H3BO3, H2BO3-) 0.05 –1 See 1

Cadmium (Cd) <0.1

Calcium Calcium ion (Ca2+) 100 - 500Carbon dioxide Dissolved CO2 Gas 1 - 10

Chloride Chloride ion (Cl-) 2,000 - 20,000Copper

Copper ion (Cu2+) <0.0005 See 1

Total Copper 0.0005 - 0.01Iron See 1

Ferrous iron (Fe2+) 0Ferric iron (Fe3+) TraceTotal iron 0.05 - 0.5

Magnesium Magnesium ion (Mg2+) 100 - 1,500Manganese

Manganese ion(Mn2+) 0 Manganese dioxide (MnO2) TraceTotal manganese 0.05 - 0.2

Molybdenum Molybdate (MoO3) TraceNitrogen Dissolved N2 Gas

Molecular nitrogen (N2) Saturation or lessAmmonium (NH4

+) 0.2 - 2Ammonia (NH3) <0.1Nitrate (NO3

-) 0.2 - 10Nitrite (NO2

-) <0.23

Oxygen Dissolved O2 Gas 5 - 15 See 2

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 - 11,000Sulfur

Sulfate (SO42-) 500 - 3,000

Hydrogen Sulfide <0.02 (preferably not detectable)Suspended Solids <100

Temperature 26-29 oC (78.8-84.2 oF) See 5

Turbidity See 6

ZincZinc ion (Zn2+) <0.01Total 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).

ing ponds or reused in adjacentcatfish ponds. In inland systems,saline effluent will remain a majorissue as more restrictions on aqua-culture effluent evolve.

Economics of producingshrimp in pondsShrimp are produced in ponds,raceways and tanks. Productioncosts vary from $2.50 to $5.00 perpound. Feed, larvae and processingare the three highest variable costs.It generally takes 2 pounds (0.91kg) of feed to produce 1 pound(0.45 kg) of shrimp. The main eco-nomic problems with culturingshrimp in the U.S. are:

� availability of low-cost, highquality feed,

� short growing season (one croponly in some areas because oftemperatures),

� high land, labor and operating(power, etc.) costs,

� foreign competition, and

� price fluctuations.

Shrimp producers generally con-tract with a processing plant to ice,de-head, grade, pack, freeze inplate freezer, and keep shrimp for 1 month in cold storage. Processorscharge an average of $0.63 perpound ($1.39/kg). About 40 per-

cent of a shrimp’s weight is in thehead. Production in ponds oftenranges from 2,000 to 8,000 poundsper acre per crop in the U.S., withan average crop of 3,500 poundsper acre.

A 20 percent profit margin is con-sidered good in this high-riskindustry. Profit margins have beennarrowing because of rising feed,labor and fuel costs and new dis-charge regulations have hurt thefarms because more money isneeded to install new recirculationpumps, etc. Market prices forshrimp were down in 2001, whichalso contributes to the risky natureof the industry.

Costs for a pilot shrimp farm insouth Texas are shown in Table 4.The farm consists of four 5-acre (2-ha) ponds, with a settling basinattached to each pond and onecommon 14.8-acre (6-ha) construct-ed wetland. A total of 50 acres isneeded for this facility. The facilityis now in operation and wasdesigned to treat water on-site andto discharge water only duringharvest. The farm takes in wateronly to fill ponds and offset evapo-ration and other water loss, andthe facility is capable of producing36 MT of shrimp per year (approx-imately 4,000 pounds per acre).The average construction cost forthe 50-acre (20-ha) facility was$9,191 per acre ($22,978/ha).

Marketing Shrimp are generally sold to theprocessing plant. The averagefarm-gate price in Texas in 2000was $3.40 per pound ($7.71/kg)for head-on shrimp (18-gram or25-count = 25 shrimp per pound).One farm has its own processingplant that de-heads the productand individually quick freezes(IQF) the tails in 5-pound (2.268-kg) clear plastic freezer bags. Thisproduct sells for about $5.90 perpound retail ($13.38/kg) at thecold storage facility, which is alsoowned by the farmer. Most farmseither sell to the plant or have theprocessing plant de-head the prod-uct, blast-freeze the tails, packthem in 5-pound (2.2-kg) waxedboxes with the plant’s or thefarm’s label on the box, and holdthe shrimp for 1 month as part ofthe processing cost. There are anumber of seafood wholesalersand seafood buyers who purchasethe product and pass the shrimpthrough the U.S. marketing chan-nels. Shrimp prices are availableon the internet athttp://www.st.nmfs.gov/st1/market_news/doc45.txt.

Major constraintsOf all natural products, seafoodcontributes more to the U.S. tradedeficit than any other productexcept oil. When all products areconsidered, seafood is fourth afteroil, automobiles and electronics.Growing populations along thecoasts are placing extra burdens oncoastal environments. Seafoodsafety is an issue as environmentaldegradation continues. TheHazard Analysis Critical ControlPoint program (HACCP) begun inDecember, 1997, placed additionalcontrols upon the seafood industry(see http://vm.cfsan.fda.gov/~dms/haccp-2a.html for more infor-mation). With limited entries, by-catch controversies, and turtle-freeand dolphin-free industry require-ments, the wild-caught seafoodindustry has little opportunity toexpand. New environmental regu-lations on our coasts also constrainaquaculture.

Disease risksShrimp diseases have also con-strained the industry. Shrimp

Figure 4. Super-intensive raceway system for shrimp.

viruses, in particular, can devastateshrimp in crowded culture condi-tions. But genetic selection pro-grams such as the one conductedby the USDA’s Marine ShrimpFarming Program have madeprogress in producing shrimpstocks that are more resistant todiseases. For example, the USDAhas developed geneticallyimproved stocks that are resistantto the Taura Syndrome Virus.Genetically superior shrimp areheld in quarantine in Hawaii andtheir offspring are sent to U.S.hatcheries. However, as moreresearch on shrimp diseases hasbeen conducted, more diseaseshave been identified. Biosecuritymeasures and regulatory con-straints on PL shrimp for stockingreduce the possibility of introduc-ing diseases, but if broodstockcome from surface water sources,the possibility is always real.

WeatherWeather in the U.S. also constrainsshrimp aquaculture. Cold weather,drought and hurricanes are theprimary concerns. In October 2000,extreme cold contributed to theloss of 1.5 million pounds (680,000kg) of shrimp on Texas shrimpfarms. The climate allows one longcrop or two short crops during thesummer months (generally fromApril to October).

Non-native introductionsLitopenaeus vannamei is the mostcommon exotic or non-nativeshrimp used in the U.S. Somereleases of these shrimp haveoccurred at harvest in the past, butstrict regulations now preventtheir accidental release into theenvironment. Pond dischargesmust be double- or triple-screenedto prevent the escape of non-nativeshrimp into the natural environ-ment. A number of groups still

object to the introduction of non-native species and farmers must beever mindful of the possiblerestriction on the use of non-nativespecies if they escape and ecologi-cal problems develop.

DischargesThere are very strict regulations forshrimp farm discharges. Stricterenvironmental regulations and thedesire to control the spread ofshrimp diseases have forced someof the farms to recirculate water.Based in part on research at SouthCarolina’s Waddell MaricultureCenter, farmers have learned toproduce shrimp using far lesswater than ever thought possible.One Texas farm is producing morethan 1.4 million pounds (637,435kg) of shrimp on 345 acres (139 ha)or about 4,000 pounds per acre(4,481 kg/ha) in a semi-closed sys-tem. The farm cut its water usefrom 4,500 gallons per pound(37,561 L/kg) of shrimp produced

Table 4. Costs for a pilot shrimp farm in Texas.

Price in US $

ContractualConstruction management, equipment operator & rental 20,045 Earth moving 72,982Electricity establishment (includes electricity to aerators) 25,000Fencing (1,500 meters or 5,000 feet installed) 10,815Insurance, repairs and maintenance, dues, water analysis, misc. 6,000Legal fees (permitting, etc.) 50,000

SuppliesWetland vegetation, truck fuel, grass seed, tools, misc. 18,400Pipe, lumber, hardware 20,073

EquipmentLand (50 acres @ $1,500/acre or 20 hectares @ $3,750/ha) 75,000Pumps 5,000Feed equipment: pond feeder, bulk bin (8-ton) 10,770Aerators, controllers and wire (60 @ 2 hp each) ($476 each) 28,565 Emergency aerator 4,449Tractor (used, 140 hp), truck (used, 3/4-ton, 4wd) 25,000Electrical generator (pto driven, 50 kva) 5,000Drains, harvest basins 7,953Scraper blade, mower 4,000Screens, nets, pl acclimation equipment 3,500Trailer & furniture (office, storage & occasional housing) 11,000Water quality lab equipment 8,500Repairs, contingencies, misc. 11,000

PersonnelOn-farm labor, consultants 36,500

Total costs $459,552

Source: Ronald Rosati, Texas A&M University—Kingsville.

in 1994 to 300 gallons per pound(2,504 L/kg) in 1998-2001. Most ofthe water is used to fill the pondsand offset evaporation. Most farmsalso have cut stocking densityfrom 50 to 36 shrimp per 10.7square feet and increased aerationfrom 8 to 10 hp per acre (20 to 25hp/ha). Some farms use as muchas 16 hp per acre (40 hp/ha) if theyrecirculate water through wet-lands. Other farms have developedadjacent shellfish ponds, whichserve as settling ponds and act asnatural filters while producing asecondary crop. Some farms havewidened and deepened their dis-charge canals and aerate them. Asa result of these changes, the TotalSuspended Solids (TSS) dischargedon intensive farms dropped from3.6 pounds (1.6 kg) per pound ofshrimp in 1994 to 1 pound (0.45kg) per 20 pounds (9kg) of shrimpin 1998. Over the same time peri-od, farms reduced:

� ammonia from 0.05 pounds perpound of shrimp to 1 pound forevery 2,500 pounds of shrimp(0.45 kg ammonia per 1,125 kgof shrimp);

� carbonaceous biochemical oxy-gen demand from 0.1 to 0.17pound (0.045 to 0.008 kg) perpound of shrimp to 1 pound(0.45 kg) for every 100 pounds(45 kg) of shrimp

These farms have also maintainedproduction at more than 4,000pounds per acre (4,481 kg/ha) ofshrimp since 1994. The develop-ment of environmentally sensitivemanagement techniques is ensur-ing the future of sustainableshrimp farming in U.S. coastalareas. In 2000, the U.S. Environ-mental Protection Agency began

reviewing aquaculture effluentswith the goal of improving dis-charge regulations in the aquacul-ture industry. Any new regulationsare to be based on scientific dataand directed at implementing eco-nomically viable, technology-basedsolutions for improving the qualityof aquaculture effluent. The regu-lations, if changed, will certainlyincrease the cost of production andrestrict the development of theindustry.

Hatchery constraintsAlmost all marine shrimp farms inthe U.S. stock non-nativeLitopenaeus vannemei because theygrow better and have better feedconversion than native species.Only a few shrimp hatcheries meetthe USDA Marine Shrimp FarmingConsortium guidelines as sourcesof non-native PL for shrimp stock-ing, so there has often been ashortage of PL during the briefU.S. stocking season. When PL arein short supply, some farms canstock only at certain densities andon certain stocking dates. Any lossof production from the few hatch-eries that exist can make a tight PLsupply even more restrictive to theindustry.

ConclusionsOpportunities for marine shrimpaquaculture in the U.S. are expand-ing, but there are many constraintsand the risks are high. In stateswhere the stocking of non-nativeshrimp is allowed, the industryhas grown. Regulations on non-native introductions and dischargeare a burden to the industry, butthrough research and Extensionprograms the industry continues

to progress. Shrimp farming, likeany new animal production indus-try, has high risks. U.S. shrimpfarming also must compete with ahighly productive internationalindustry and with other develop-ment interests for valuable coastalsites.

Suggested readingBoyd, C.E. 2001. Inland Shrimp

Farming and the Environment.World Aquaculture 32 (1): 10-12.

Boyd, C.E. and C.S. Tucker. 1998.Pond Aquaculture WaterQuality Management. KluwerAcademic Publishers, Boston,Mass.

Browdy, C.L. and D.E. Jory, 2001.The New Wave, Proceedings ofthe Special Session onSustainable Shrimp Farming.World Aquaculture Society,Baton Rouge, LA.

Treece, G.D. and M.E. Yates, 2000.Laboratory Manual for theCulture of Penaeid ShrimpLarvae. TAMU Sea GrantPublication #88-202(R).

Villalon, J.R. 1991. PracticalManual for Semi-intensiveCommercial Production ofMarine Shrimp. TAMU SeaGrant Publication #91-501. Hardcopy is out of print but manualcan be downloaded free ofcharge from the National SeaGrant Office Web site at http://nsgl.gso.uri.edu/tamu/tamuh91001/tamuh91001index.htm.

Wyban, J. A. and J. N. Sweeney.1991. The Oceanic InstituteShrimp Manual: IntensiveShrimp Production Technology.The Oceanic Institute, P. O. Box25280, Honolulu, Hawaii 96825.

The work reported in this publication was supported in part by the Southern Regional Aquaculture Centerthrough Grant No. 00-38500-8992 from the United States Department of Agriculture, Cooperative StateResearch, Education, and Extension Service.

SRAC fact sheets are reviewed annually by the Publications, Videos and Computer Software SteeringCommittee. Fact sheets are revised as new knowledge becomes available. Fact sheets that have notbeen revised are considered to reflect the current state of knowledge.