This article was downloaded by: [University of Stellenbosch]On: 08 May 2013, At: 16:17Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,UK

Journal of Applied AquaculturePublication details, including instructions forauthors and subscription information:http://www.tandfonline.com/loi/wjaa20

Production of the Pacific WhiteShrimp, Litopenaeus vannamei,in High-Density Greenhouse-Enclosed Raceways Using LowSalinity GroundwaterTzachi M. Samocha a , Addison L. Lawrence b , CraigA. Collins c , Frank L. Castille b , William A. Bray b ,Craig J. Davies d , Philip G. Lee d & Gary F. Wood ca Texas A&M University System, Texas AgriculturalExperiment Station, Shrimp Mariculture ResearchFacility, 4301 Waldron Road, Corpus Christi, TX,78418, USAb Texas A&M University System, Texas AgriculturalExperiment Station, Shrimp Mariculture ResearchLaboratory, 1300 Port Street, Port Aransas, TX,78373, USAc Wood Brothers Farms, 77 Biltmore Estates,Phoenix, AZ, 85016, USAd University of Texas, Marine Biomedical Institute,200 University Boulevard, Galveston, TX, 77550, USAPublished online: 25 Sep 2008.

To cite this article: Tzachi M. Samocha , Addison L. Lawrence , Craig A. Collins ,Frank L. Castille , William A. Bray , Craig J. Davies , Philip G. Lee & Gary F. Wood(2004): Production of the Pacific White Shrimp, Litopenaeus vannamei, in High-Density Greenhouse-Enclosed Raceways Using Low Salinity Groundwater, Journal ofApplied Aquaculture, 15:3-4, 1-19

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Production of the Pacific White Shrimp,Litopenaeus vannamei, in High-Density

Greenhouse-Enclosed RacewaysUsing Low Salinity Groundwater

Tzachi M. SamochaAddison L. Lawrence

Craig A. CollinsFrank L. CastilleWilliam A. BrayCraig J. DaviesPhilip G. LeeGary F. Wood

ABSTRACT. Two nursery trials and one grow-out culture trial with Pa-cific white shrimp, Litopenaeus vannamei, were conducted at an inlandfarm near Gila Bend, Arizona, using low-salinity (1.8 to 2.6 ppt) ground-

Tzachi M. Samocha, Texas A&M University System, Texas Agricultural Experi-ment Station, Shrimp Mariculture Research Facility, 4301 Waldron Road, CorpusChristi, TX 78418.

Addison L. Lawrence, Frank L. Castille, and William A. Bray, Texas A&M Univer-sity System, Texas Agricultural Experiment Station, Shrimp Mariculture ResearchLaboratory, 1300 Port Street, Port Aransas, TX 78373.

Craig A. Collins and Gary F. Wood, Wood Brothers Farms, 77 Biltmore Estates,Phoenix, AZ 85016.

Craig J. Davies and Philip G. Lee, University of Texas, Marine Biomedical Insti-tute, 200 University Boulevard, Galveston, TX 77550.

Journal of Applied Aquaculture, Vol. 15(3/4) 2004http://www.haworthpress.com/web/JAA

2004 by The Haworth Press, Inc. All rights reserved.Digital Object Identifier: 10.1300/J028v15n03_01 1

Please note that this electronic prepublication galley may contain typographical errors and may be missingartwork, such as charts, photographs, etc. Pagination in this version will differ from the published version.

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water. Trials were conducted in greenhouse-enclosed concrete racewayswith bottom area of 97.5 m2 and water volume of 147.6 m3. Excellentsurvival (98.1±2.9%), FCR (0.7:1), and yield (2.22±0.17 kg/m2) wereobtained in a five-week nursery study with stocking density of about20,000 postlarvae/m2. In the grow-out trial, survival as high as 86% anda yield of 4.39 kg/m2 of shrimp with a mean weight of 14.7 g wereachieved in 107 days from an initial mean weight of 0.5 g. These trialsindicate that the Pacific white shrimp can be raised at very high densitieswith good survival using low-salinity groundwater. Composition of thegroundwater is reported. [Article copies available for a fee from The HaworthDocument Delivery Service: 1-800-HAWORTH. E-mail address: <docdelivery@haworthpress.com> Website: <http://www.HaworthPress.com> 2004 by TheHaworth Press, Inc. All rights reserved.]

KEYWORDS. Pacific white shrimp, Litopenaeus vannamei, low-salin-ity groundwater, nursery, raceway, grow-out, high density

INTRODUCTION

Sporadic viral disease outbreaks in farm-raised shrimp have resultedin severe crop losses all over the world. Thus, one of the limiting factorsinhibiting further expansion of the shrimp farming industry is the occur-rence of disease epizootics (Lightner et al. 1997). White spot syndromevirus (WSSV) is one of the viruses that has affected world production ofcultured shrimp and is still widely distributed in many countries (Joryand Dixon 1999; Wang et al. 1999). In some cases disease outbreakshave implicated shrimp farming intensification and increased occur-rence of viral diseases in the seawater source. When virulent pathogensare found in wild populations and in natural waters, the control of dis-ease outbreaks in cultured stocks becomes very difficult and costly. Asa temporary solution and to minimize losses, some producers have relo-cated their farms to new coastal sites where disease vectors are lessabundant. Another practice, used mainly in the Far East with the blacktiger shrimp, Penaeus monodon, is to raise shrimp in inland ponds farfrom coastal waters (Flaherty and Vandergeest 1998).

The species of choice of the shrimp farming industry in the westernhemisphere is the Pacific white shrimp Litopenaeus vannamei. Thisspecies has been reported in hypersaline water of 40 ppt and higher andin low salinity water of 1-2 ppt (Menz and Blake 1980). The preferablesalinity for culturing this species is not well documented. Several au-

2 JOURNAL OF APPLIED AQUACULTURE

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thors (Hirono 1989; Stern et al. 1990; Villalon 1991) report that in Ec-uador postlarvae (PL) of this species have been acclimated to lowsalinity water (<1 ppt) in culture situations. In a salinity preferencestudy with PL of this species, Mair (1980) found a strong preference forsalinity between 1 and 8 ppt. Nevertheless, there is very little publishedinformation on growth and survival of this shrimp at low salinities.Samocha et al. (1998) working with this species in an indoor recirculat-ing system did not find statistically significant differences in growthand survival in a 70-day trial when working with water salinities of 2, 4,and 8 ppt. On the other hand, Bray et al. (1994) found significantlylower growth of juveniles of this species in salinity of 25 and 35 ppt (orhigher salinity) compared with 5 and 15 ppt. These examples demon-strate the Pacific white shrimp tolerance to low salinity water. However,recent interest in culturing shrimp in low salinity groundwater raisesnew questions, as well water can differ considerably in ion compositionfrom diluted natural seawater. Published reports concerning the growthand survival of this species in well water or inland surface water are lim-ited. Successful culture of this species in saline groundwater of about 28ppt was documented by Smith and Lawrence (1990) when juvenileswere raised in earthen ponds (25 shrimp/m2) from 1.2 g to 19.9 g in 120days with 86.7% survival. In another study, Scarpa and Vaughan (1998)examined different parameters affecting PL acclimation to freshwaterand the effect of low salinity on growth and survival of this species.Hardness (as CaCO3) level greater than 150 mg/L was suggested by theauthors for good survival and growth. According to their findings, in-creased survival of freshwater-acclimated PL can be expected whenadding magnesium rather than calcium to low-hardness freshwater. Inanother study, Emberson et al. (1999) reported a yield as high as 6,770kg/ha from outdoor earthen ponds using 2.0 ppt groundwater in theSonora Desert, USA. In a updated report of the same study, Samocha etal. (1999, 2002) stated that production as high as 12,000 kg/ha was ob-tained when a small pond (0.1 ha) was stocked at high density (109shrimp/m2).

Limited data are available concerning both the nursery and grow-outphases of Pacific white shrimp culture using high stocking densities inlow-salinity groundwater. The objectives of the current study were todemonstrate that (1) early PL and juvenile shrimp of Pacific whiteshrimp can be reared successfully at high density in low salinity water,and (2) juvenile shrimp can be raised to marketable size at high densityin low salinity water.

Samocha et al. 3

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MATERIALS AND METHODS

Farm Site Description

Trials were conducted at the Wood Brothers Shrimp Farm, GilaBend, Arizona1 located in the Sonora Desert 300 km northeast of theGulf of California. The 15-ha shrimp farm is a division of a 500-ha di-versified agricultural operation raising wheat and olives. Two geother-mal (25°C) deep water wells (250 m) with low salinity (1.8 to 2.6 ppt)provided the water for raising the shrimp. Water was delivered by pipedirectly into the culture vessels with no prior treatment. Some character-istics of this water and the differences in ionic composition between thiswater and natural seawater diluted to the farm water salinity are summa-rized in Table 1.

Culture System Description

The nursery and grow-out studies were conducted in greenhouse-en-closed concrete raceways. Raceway walls were painted black, while bot-toms were painted white using a food-grade epoxy paint (Epmar Corp.,Santa Fe Springs, California). Each raceway had a bottom area of 97.5 m2

(28 m × 3.48 m) with an operational water volume of 147.6 m3 and a cen-ter partition (24 m × 0.2 m) extending within 2 m from the end-walls.Raceways were built with 1% bottom slope and 0.3-m deep settling basinat the deep end. Water depth of the raceway at the deep end was 1.8 m and1.2 m in the shallow end. A perforated PVC pipe (30.5-cm in diameter)covered with 500-µm netting that was positioned at the center of the set-tling basin to serve as a drain for water exchange and pump- driven watercirculation. A 30.5-cm PVC pipe returned water from the settling basininto a 5.3-m3 concrete reservoir located near the shallow end of the race-way. A 3-hp pump delivered water from this reservoir back to the race-way with an alternate loop directing the water into a rapid sand filter and/or a Venturi injectors. Water was pumped back into the raceway througha perforated PVC spray-pipe (5.1 cm in diameter) and/or a bottom mani-fold (7.6 cm PVC pipe with spray nozzles).

Three banks of four airlift pumps (7.6 cm in diameter) were posi-tioned on each side of the center partition to provide a constant counter-clockwise current. Raceway water circulation could be further enhanced

4 JOURNAL OF APPLIED AQUACULTURE

1. Use of trade or manufacturer’s name does not imply endorsement.

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by injecting water via the bottom manifold and/or the spray pipe. Sup-plemental aeration was provided by six, 3-m air diffusers (Bio-Weavediffuser hose, Aquatic Eco-Systems, Inc., Apopka, Florida) positionedalong the raceway sidewalls. A flat polypropylene heat exchanger(Heliocol Arizona, Inc., Phoenix, Arizona) was placed between the cen-ter partition and the end wall at the shallow end to maintain optimal wa-ter temperature in the raceway during the first nursery trial. This heatexchanger was operated by solar energy and was supported by a naturalgas-fired boiler.

Postlarvae (PL) Trial

The objective of this study was to evaluate the feasibility of raisingyoung PL at high stocking density in low salinity groundwater. Twodays before stocking, two raceways were filled with well water to about10% capacity and salinity was adjusted to 17 ppt with artificial sea salt(Crystal Sea Bioassay, Marine Enterprises Int., Baltimore, Maryland).Culture water was fertilized with urea, triple superphosphate and so-dium silicate to provide a final nutrient concentration of 10, 1 and 1 mg/L for the N, P and Si, respectively. Raceway water was inoculated withthe diatom Chaetoceros muelleri at a concentration of 50,000 cells/mL.

Four million eight-day-old postlarvae (PL8) from domesticated stocksof the USDA Marine Shrimp Farming Program were shipped by truck instyrofoam boxes from Harlingen Shrimp Farm Hatchery (Los Fresnos,Texas). Shipping water temperature, salinity and PL density were 18°C,17 ppt and 1,500 PL/L, respectively. Water temperature in shippingbags upon arrival varied between 22 and 24°C, while dissolved oxygenvaried between 15 and >20 mg/L. Postlarvae were kept in four 750-Ltanks (two tanks per raceway) for 2-hour acclimation before they werereleased into the raceways. Throughout the acclimation process dis-solved oxygen was maintained above 15 mg/L using oxygen from a cyl-inder. Mortality due to shipping stress was estimated at 1.9% and 2.9%for the first and second raceway, respectively. Acclimation to low salin-ity water was conducted over a 28-day period (see section below). Toreduce stress during the acclimation process, raceways were stockedbased on population estimates provided by the hatchery. The meanweight of the PL at stocking was 0.0025 g while stocking densities inthe two raceways were 19,200 PL/m2 (12,700 PL/m3) and 20,400 PL/m2 (13,500 PL/m3).

Dissolved oxygen, temperature, pH and salinity in the raceways weremonitored twice daily. Total ammonia-nitrogen, nitrite-nitrogen, and ni-

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trate-nitrogen were monitored three times a week using Hach DR 2010procedures (Hach Company, Loveland, Colorado). Algal-cell counts inthe culture water were performed with a hemocytometer on samplescollected every other day starting seven days after stocking. Water sa-linity in the raceways was lowered from the initial 17 ppt to 2.0 ppt overa 28-day period using the farm’s well water. New water was added toboth raceways, with no water discharge until day 12. Daily water exchangewas increased from 10% of the volume on day 12, to 84% on day 25.

Shrimp were fed a 45% crude protein dry diet (“45/10” Rangen, Inc.,Buhl, Idaho) which was supplemented for the first eight days withnewly hatched Artemia nauplii. Diet particle size (“swim-up,” Fry # 1and Fry # 2) was changed based on shrimp size. Diet was fed five timesdaily (7:00, 10:00, 14:00, 16:00 and 19:00). Daily rations from day 10forward varied between 4.5% and 11% of the total estimated shrimpbiomass in each raceway. Shrimp growth was monitored three timesweekly from a group sample. Shrimp yields in both raceways were de-termined by weighing all of the shrimp after draining excess water fromthe shrimp for 20 seconds. Survival and average weekly growth rateswere calculated from the harvested biomass and the shrimp meanweight as determined by group weight samples (each with 19 to 75shrimp) collected during the harvest. One raceway was harvested 34days after stocking while the other after 35 days.

Juvenile Trial

The objective of this trial was to evaluate the feasibility of rearing ju-venile shrimp (0.091 g) in low salinity water at high stocking density.The study was conducted in four raceways filled with well-water (2.2ppt) enriched with cultured algae. All raceways were stocked at a den-sity of 2,670 shrimp/m2 (1,760/m3) with juveniles collected from a sin-gle raceway harvested on the day of the study initiation. Similar initialbiomass load (0.243 kg/m2 or 0.16 kg/m3) was placed in all four race-ways. Shrimp stocked into three raceways were transferred directlyfrom harvest baskets. Shrimp used for stocking the fourth raceway werekept for four hours after the harvest in two 2,000-L tanks with oxygensupply before they were transferred into the raceway. No shrimp mor-tality was observed during the harvest and stocking process. Monitoringfrequencies and testing of water quality parameters were similar tothose described for the first trial. Shrimp were fed four times daily thesame dry feed mentioned previously. For the first 13 days, shrimp werefed the Rangen Fry # 2 diet. From day 14 until harvest, shrimp were fed

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the Rangen Fry # 3 diet. Daily rations varied between 10 and 15% of thetotal estimated shrimp biomass in each raceway. Rations were adjustedbased on consumption, water quality condition and weight samples col-lected every three to four days. Shrimp yield, survival, average weeklygrowth and mean weight at harvest were recorded using the same meth-ods described for the first trial.

Grow-Out Trial

The objective of this study was to evaluate the feasibility of produc-ing marketable-size Pacific white shrimp in concrete raceways with lowsalinity well water using various stocking densities. Raceways werestocked with juvenile shrimp (0.5 g) at densities of 74, 93, 107, and 346shrimp/m2. Feed was offered three times daily (8:00, 12:00, and 17:00).During the first 69 days, shrimp were fed the same 45% protein feed en-riched with squid meal (“45/10” Fry # 4 diet, Rangen, Inc.). From day70 until harvest, shrimp were fed a 40% crude-protein feed withoutsquid meal (“40/0, 3/32,” Rangen, Inc.). Water quality monitoring andfrequencies were similar to those described for the first trial. Shrimpgrowth was monitored weekly from a group weight. Three racewayswere harvested 107 days after stocking, while one raceway was har-vested after 94 days. Shrimp yield, survival, average weekly growth andmean weight at harvest were determined as in the PL trial.

RESULTS

Postlarvae Trial

An algal bloom was observed four days after stocking in both race-ways with algal density reaching a density of 375,000 cells/mL. Goodalgal blooms were maintained throughout the study in both raceways.Averages for selected daily and weekly water characteristics are pre-sented in Table 2. Afternoon water pH levels were higher than in themornings. Throughout the trial, dissolved oxygen levels were main-tained above 62% saturation in both raceways. Stocking and harvestdata from this trial are summarized in Table 3. Raceways showed aslight difference in yields (2.34 kg/m2 vs. 2.1 kg/m2). Shrimp survival inboth raceways was high with very low FCR values of 0.7 for both race-ways.

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Juvenile Trial

Table 2 provides the average values for selected daily and weeklywater quality parameters in the four raceways during the trial. Through-out the trial dissolved oxygen level stayed closed to saturation. Maxi-mum ammonia level was a little above 1 mg/L while the maximumnitrite level was below 0.7 mg/L. The average shrimp weight at harvestwas 0.37 g with survival of 81.8 ±11.7% and FCR of 1.22± 0.19 (Table 3).

Grow-Out Trial

Dissolved oxygen and water pH levels were always lower in thehigh-density raceway than the low-density raceways. Although waterexchange rates in the high-density raceway were about seven timeshigher than the low-density raceways, ammonia and nitrite levels in thehigh-density raceway were always higher than the other low-densityraceways (Table 4). Differences in shrimp growth between the high-density raceway (346 shrimp/m2) and the low-density raceways wereobserved four weeks after stocking (Figure 1). The average weeklygrowth rate of the shrimp in the low-density raceways was 1.36 g/week(Table 5). This growth rate was much higher than the growth found forthe high-density raceway (1.03 g/week). Shrimp survival and yield inthe high density raceway were the highest among all raceways (86.1%and 4.39 kg/m2, respectively; Table 5). Mean survival for the low-den-sity raceways was 66.9±6.8% with average yield of 1.1±0.1 kg/m2. No-ticeable shrimp mortality in the raceway stocked at 93 shrimp/m2

resulted in early harvest (after 94 days). Histology of moribund shrimpfrom this raceway showed intestinal inflammatory signs characteristicof blue-green algal toxicity. FCR values for all raceways were high withthe lowest value found in the high-density raceway.

DISCUSSION

The high survival rate reported for the PL trial can be easily ex-plained by the variability in PL counts experienced by commercialshrimp hatcheries. Since PL population size was estimated only at thehatchery from aliquot samples, coefficient of variance of 5% to 10%can be expected. Thus the high survival rates (98.1 ± 2.9%) observed inthe PL trial may suggest that the initial stocking density of the PL was a

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TA

BLE

4.D

isso

lved

oxyg

en,t

empe

ratu

re,p

H,T

AN

,nitr

ite,n

itrat

e,an

dda

ilyw

ater

exch

ange

reco

rded

ina

grow

-out

tria

lcon

duct

edin

race

way

syst

ems

usin

glo

w-s

alin

itygr

ound

wat

er.V

alue

sre

pres

entm

ean

(±st

anda

rdde

viat

ion)

with

the

num

ber

ofob

serv

atio

nsin

pare

nthe

ses.

Tria

lD

O(m

g/L)

Tem

p.(°

C)

pHT

AN

NO

2-N

NO

3-N

Wat

erex

chan

ge(%

/day

)

ampm

ampm

ampm

(mg/

L)

Low

dens

itya

6.4±

0.0

(305

)7.

2±0.

0(3

05)

27.4

±0.1

(305

)28

.6±0

.2(3

05)

8.0±

0.0

(305

)8.

4±0.

1(3

05)

0.15

±0.0

4(1

83)

0.25

±0.0

5(2

44)

8.86

±0.3

9(2

31)

21.4

±1.2

3(3

05)

Hig

hde

nsity

b5.

8±0.

9(1

06)

6.4±

1.0

(106

)27

.1±1

.1(1

06)

28.4

±1.1

(106

)7.

9±0.

3(1

06)

8.3±

0.3

(106

)0.

30±0

.20

(45)

0.28

±0.1

9(4

5)9.

09±1

.94

(45)

148.

1±12

3.2

(106

)a

Obs

erva

tions

from

thre

era

cew

ays.

bO

bser

vatio

nsfr

omon

era

cew

ay.

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little higher than the reported values. The high yields in this trial (2.22 ±0.17 kg/m2) suggest that the farm’s low salinity ground water can sup-port production equal to that which has been reported with higher salin-ity water (Samocha et al. 2002). Furthermore, the low FCR values(0.7:1) associated with the high survival and yields suggest that a largeportion of the nutritional requirements of the shrimp in this study weremet by natural productivity developed in the raceways.

The high yield (4.39 kg/m2) of marketable size shrimp (14.72 g) ob-tained in the high-density raceway in the grow-out trial shows that thelow salinity ground water used in this trial could support high shrimpbiomass with good survival to market size. It is interesting to note that inspite of the chronic higher total ammonia levels in this raceway, sur-vival was much higher than the low-density raceways. We suspect thatthe lower daily water-exchange rates in the low-density raceways (21.1-22.8%/day) along with some over-feeding, as indicated by the highFCR values (FCR 2.66:1 to 3.22:1), may have resulted in formation oftoxic hydrogen sulfide which affected shrimp survival. Although nomeasurements of hydrogen sulfide were made during this trial, a hydro-gen sulfide odor was detected every time the bottom of these racewayswas stirred.

Samocha et al. 13

20

18

16

14

12

10

8

6

4

2

00 7 14 21 28 35 42 49 56 63 70 77 84 91 98 105

DAYS

107/m2 346/m2 74/m2 93/m2

WE

IGH

T(g

)

FIGURE 1. Growth of Litopenaueus vannamei in raceways at low stockingdensities (74 /m2, 93/m2, and 107/m2) and high density (346/m2) in low-salinity(2.2 ppt) groundwater.

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TA

BLE

5.A

vera

gew

eigh

t,yi

eld,

surv

ival

,F

CR

,da

ilyan

dw

eekl

ygr

owth

ofLi

tope

naeu

sva

nnam

eiju

veni

les

(0.5

g)st

ocke

dat

high

(346

/m2 )

and

low

dens

ities

(74,

93an

d10

7/m

2 )in

conc

rete

race

way

sus

ing

low

-sal

inity

grou

ndw

ater

.

Sto

ckin

gde

nsity

Dur

atio

n(d

)A

vera

gew

eigh

t(g)

Gro

wth

Yie

ld(k

g/m

2 )S

urvi

val(

%)

FC

R

(g/d

ay)

(g/w

eek)

a

Low

94-1

0718

.48±

1.15

b0.

18±0

.01

1.36

±0.0

41.

11±0

.10

66.9

±6.8

2.75

±0.4

3

Hig

h10

714

.72±

2.52

0.14

1.03

4.39

86.1

2.11

aC

alcu

late

dw

eekl

yav

erag

egr

owth

from

1g

size

.b

Sta

ndar

dde

viat

ion.

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Shrimp growth rates in the low-density raceways were higher than inthe high-density raceway. It seems likely that the higher density re-sulted in a lower weekly growth rate as documented in previous studies(Browdy et al. 1993; Hopkins et al. 1995; Williams et al. 1996; Davisand Arnold 1998). Another interesting finding was the high weeklygrowth rate of the shrimp in the low-density raceways from week three toweek ten of the study (1.26 to 1.44 g/week) and the decrease in growthrates from week ten until the harvest (1.08 and 1.13 g/week) (Figure 1).The switching to lower protein diet on week ten may have resulted inthe decrease in shrimp growth observed in this study. Data obtained byJiang et al. (1999) suggest that a high protein diet is needed for optimalgrowth of this species when it is raised in salinities above or below itsiso-osmotic point (24.7 ppt for L. vannamei as reported by Castille andLawrence 1981). This finding was also supported by the work of Rob-ertson et al. (1993) in which increasing feed protein level improvedgrowth of this species when kept at low (5 ppt) and high (45 ppt) salin-ity. Nevertheless, it is possible that this lower growth was a result of lessfavorable protein to energy ratio in the lower protein diet as suggestedby Kureshy et al. (2002). Since these feeds were not analyzed for pro-tein/energy content, answering this question will require further studies.Clearly, more research is needed to better understand the interaction be-tween shrimp growth in low salinity waters and the protein/energy require-ments for the Pacific white shrimp in high density production systems.

Ionic composition of groundwater can vary from site to site evenwhen sites are only 3 km apart (Saoud et al. In press). Comparing theionic composition of the groundwater from these trials to natural seawa-ter diluted to the farm’s salinity may identify some of the ions that play amajor role in low-salinity production systems of the Pacific whiteshrimp. Table 1 compares the ionic composition of natural seawater di-luted with distilled water to the farm’s salinity and the groundwaterused in our trials. The comparison was made based on the average val-ues obtained from the two wells used in these studies. Similar concen-trations were found only in sodium and sulfate. The levels (proportions)of chloride, magnesium, and potassium were lower than in natural sea-water. On the other hand, the levels of calcium, boron, phosphorus,iron, lead and bicarbonate were higher than the calculated levels for di-luted seawater.

The information available in the literature concerning the effects ofdifferent natural minerals in ground saline water on growth and survivalof the Pacific white shrimp is limited. Saoud et al. (In press) looked atthe ionic makeup of various inland well waters from Alabama, Florida,

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Mississippi and Texas and evaluated the effect of these sources ongrowth and survival of young PL (PL 10, 15 and 20) of this species.These studies suggest that PL performance can be affected by the age ofthe PL and the source of water. They concluded that the older the PL thehigher the survival in acclimation to low salinity water. In addition,shrimp survival appeared to be positively correlated with ions such asK, Mg and SO4 and negatively correlated with a high concentration ofiron.

Laramore et al. (2001) in their work with PL and juveniles of this spe-cies found similar age/size related tolerance to low salinity acclimation.Similarly, McGraw et al. (2002) suggested that older PL had bettersurvival in acclimation to low salinities. Scarpa and Vaughan (1998) reportedproduction of 15 g shrimp in four months in a closed recirculating fresh-water system and suggested that water hardness of 150 mg/L as CaCO3 isneeded for raising this species in low salinity water. In another study,Allen et al. (2000) in their work with young postlarvae (PL 15-27) sug-gested that magnesium at 102 ppm had no effect on survival, while bothcalcium (170 ppm) and potassium (300 ppm) had detrimental effects onsurvival. The authors conclude that sodium and chloride, in the form ofNaCl, are the most important ions affecting survival under the condi-tions of their studies.

Unlike the water used by the previous authors, the culture water inour studies had almost three times higher Cl level (891 vs. 300 ppm),about seven times lower Mg level (15.3 vs. 102 ppm) and 24 timeslower K concentration (12.5 vs. 300 ppm). Although the Na concentra-tion in the Allen et al. (2000) work was not specified, the fact that im-proved shrimp survival was observed when 80 ppm of sodium wasadded to the water suggests that their water had very low sodium level.The higher Cl and Na and the lower K levels in the water used in ourstudies may explain why we have not found noticeable shrimp mortalityin the presence of 187 ppm of Ca as observed by Allen et al. (2000)when 170 ppm of Ca or 300 ppm of K were added to the water.

The present study demonstrated excellent survival and yields at highdensities when PLs were acclimated from 17 to 2 ppt over a 26-day pe-riod. These results are not in agreement with the poor growth and sur-vival observed by Laramore et al. (2001) when working with PL. Ourstudies showed no adverse effect on the shrimp when they were raisedto marketable size at low salinity water. As ionic composition of the wa-ter used by Laramore et al. (2001) was not provided, we can only specu-late that differences in shrimp performance might have been related todifferences in ionic composition of the water between the two sites.

16 JOURNAL OF APPLIED AQUACULTURE

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These findings suggest that more studies are needed to better define theoptimal ionic composition of inland low-salinity water for the produc-tion of the Pacific white shrimp.

SUMMARY

The trials summarized in this paper demonstrate that the Pacificwhite shrimp can be raised using low salinity (approximately 2 ppt)groundwater at high densities (up to 20,000/m2) during the nurseryphase with high survival (98.1±2.9%) and yield (2.22±0.17 kg/m2).Marketable-sized shrimp can also be produced under high density (up to346 shrimp/m2) with good survival (>86%) and high yield (4.39 kg/m2).

ACKNOWLEDGMENTS

These studies were conducted in part with funding from NOAA(Award No. NA67FD0036); The USDC, MSFP, CSREES (Grants No.95-38808-1424 and No. 92-38808-6920); TAES, TAMUS (ProjectH-8158); Texas ATP (Grant No. 004952-079); and the Wood BrothersShrimp Farm, Gila Bend, Arizona.

REFERENCES

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Bray, W.A., A.L. Lawrence, and J.R. Leung-Trujillo. 1994. The effect of salinity ongrowth and survival of Penaeus vannamei, with observations on the interaction ofIHHN virus and salinity. Aquaculture 122:133-146.

Browdy, C.L., J.D. Holloway, C.O. King, A.D. Stokes, J.S. Hopkins, and P.A. Sandifer.1993. IHHN virus and intensive culture of Penaeus vannamei: Effects of stockingdensity and water exchange rates. Journal of Crustacean Biology 13:87-94.

Castille, F. Jr., and A.L. Lawrence. 1981. The effect of salinity on the osmotic, sodium,and chloride concentrations in the hemolymph of eurohaline shrimp of the genusPenaeus. Comparative Biochemistry and Physiology 68A:75-80.

Davis, D.A., and C.R. Arnold. 1998. The design, management and production of a re-circulating raceway system for the production of marine shrimp. Aquacultural En-gineering 17:193-211.

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Jiang, D., A.L. Lawrence, H. Gong, F.L. Castille, and W.H. Neill. 1999. Influences ofdietary protein and energy on survival and growth of Penaeus vannamei juveniles athigh salinity. Book of Abstracts. World Aquaculture ’99. World Aquaculture Soci-ety, Baton Rouge, Louisiana.

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