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EXPERT TOPIC - SHRIMP

The International magazine for the aquaculture feed industry

International Aquafeed is published six times a year by Perendale Publishers Ltd of the United Kingdom.All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2013 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

INCORPORAT ING f I sh fARm ING TeChNOlOGy

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Welcome to Expert Topic. Each issue will take an in-depth look at a particular species and how its feed is managed.

SHRIMPEXPERT TOPIC

ShrimpFarmed shrimpwas a$US10.6billion indus-try in 2005 (WWF).The species is one ofthe fastest growing in aquaculture with anapproximaterateof10percentannually.Theproduction of whiteleg shrimp (Litopenaeusvannamei, formerly Penaeus vannamei) inparticular, generated the highest value ofmajorculturedspeciesat$US11.3billion.

L. vannameiwasfirstcultivatedinFloridain1973fromlarvaespawnedandshippedfromawild-caughtmated female fromPanama. In1976,duetogoodpondresultsandadequatenutrition, the culture of L. vannamei beganin South and Central America. By the early1980s,throughintensivebreedingandrearingtechniques,L. vannameiwasbeingdevelopedin the USA (including Hawaii), and much ofCentralandSouthAmerica(FAO).

L. vannamei ispopularbecauseof itshighyield and short grow out period. The yieldper hectare is up to three times thatof thegiant tiger shrimp (Penaeus monodon). Thegrow out period is also shorter for L. van-namei,60-90days,comparedto90-120daysforP. monodon.Overall,itcostsabouthalfasmuch to produce a kilo of L. vannamei as itdoestoproduceakiloofP. monodon.

1 ChinaAlthough, L. vannamei was introduced intoAsiain1978-9,itwasnotuntil1996thatthespecieswascultivatedonacommercialscale.FirstinMainlandChinaandTaiwanandsubse-quentlytothePhilippines,Indonesia,Vietnam,Thailand,MalaysiaandIndia.

Thelargestseafoodproducerandexport-er in theworld,China alsoboasts a large L. vannamei production industry,withMainlandChina producing more than 270,000 met-ric tonnes in 2002. Production reached anestimated 300,000 metric tonnes (71%of the country’s total shrimp

production) in 2003 andhit 700,000 tonnesin2004(NetworkofAquacultureCentresinAsia-Pacific).

More InforMatIon: www.enaca.org

by M

arni

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42 | InternatIonal AquAFeed | May-June 2013 May-June 2013 | InternatIonal AquAFeed | 43

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2 IndiaInthe1990s,Indianshrimpaquacultureexpe-rienced rapid growth. Production increasedfrom 30,000 tonnes in 1990 to 102,000tonnes in 1999 (FAO). This expansionbrought economic success for the country.By the start of the 21st century, the shrimpaquaculture sector accounted 1.6 percentof Indian export earnings and employed anestimated200,000people.

Yet the development of shrimp aquac-ulture has become more controversial. Theintroduction of L. vannamei in 2009 has ledto widespread illegal farming and posed thethreatofdisease.However,thereareorgani-sations dedicated to tackling the problem.One example is the Coastal AquacultureAuthority (CAA) which aims to shut downunregistered shrimp hatcheries and farms.Thescaleoftheissueisratherlargeasoutof14,549CAA registered farms, just 246 havepermissiontocultivatewhitelegshrimp.

More InforMatIon:www.fao.org/docrep/x8080e/x8080e08.htmwww.thehindu.com/news/cities/Vijayawada/arti-cle2878953.ece

3 EcuadorThe1970ssetapresidentforthedevel-opment of Ecuador’s shrimp farmingindustry.L. vannamei,capturedfromthebeachsurfwastransferred into20-hec-tare ponds that Ecuadorian producersbuiltonmudflats.

During the mid-1970s, animalfeed and pet food company, RalstonPurinabeganconductingpondtrialsinEcuador to demonstrate the benefitsoffeeding.

As land and labour were cheap,disease was rare and wild seed was inabundance,theshrimpfarmingbusinesswas profitable and by 1977, approxi-mately 3,000 hectares of extensiveshrimp farms had been developed inEcuador.

As a result, shrimp feed mills weredeveloped during the 1980s, markingthetransitionofEcuadorian farms fromextensivetosemi-intensiveproduction.

More InforMatIon:www.shrimpnews.com/FreeReportsFolder/HistoryFolder/HistoryWorldShrimpFarming/ChamberlainsHistoryOfShrimpFarming.html

4 BrazilAlthough shrimp farming was alreadyoperational during the 1980s, it wasthe introductionofL. vannamei in1992 thatallowedforaswiftexpansioninBrazil’sshrimpfarming industry. Shrimp culture is now oneofthemostorganisedsectorswithinBrazilianaquaculture.

In 2003, the total production of L. van-nameireached90,190tonnesproducedfrom14,824 ha of shrimp ponds. In some states,productivity reached 8,700 kg/ha/year withthe best yields obtained in the northeastregion.

With exports reaching 60,000 tonnes in2003,representing60.5%ofthetotalBrazilianfisheryexportandgeneratingUS$230millionfor the Brazilian economy, shrimp culture isnow one of the most important economicactivitiesintheNortheastregion.

Most of the shrimp farms are small scale(75%),followedbymedium(9.6%)andlargescale (5.52%). The average yield increasedfrom1 015 kg/ha/year in 1997 to 6,084 kg/ha/yearin2003,comparedtoaninternationalaverageof958kg/ha/year(FAO).

More InforMatIon:

www.fao.org/fishery/countrysector/naso_brazil/en

5 ThailandShrimpfarminghasbeenpractisedinThailandformorethan30years,withitsdevelopmentexpandingrapidlyduringthemid-1980s.Thisexpansion was supported by advances inshrimpfeedandthesuccessfulproductionoflarvaein1986.

The most popular shrimp cultivated inthecountryisthegianttigerprawn(Penaeus monodon) which accounts for 98 percent ofshrimpproductionandaround40percentoftotal brackish water aquaculture production(FAO). L. vannamei was first introduced toThailandinthelate1990sasanalternativetothenativeP. monodon.

TheproductionofL. vannameiinThailandrapidly increased from10,000metric tons in2002 (Briggs et al. 2004) to approximately300,000 metric tons in 2004, which com-prised 80 percent of total marine shrimpproduction.

More InforMatIon:www.fao.org/fishery/countrysector/naso_thailand/en

India’sindigenousshrimp

The Raj iv Gandhi Centre forAquaculture (RGCA) inTamil Nadu,Indiahasproducedaspecificpathogen

free variety of shrimp.The new variety isset tohelp commercial shrimp farmers andboostIndia’sseafoodexports.

The selectively bred mother shrimps arecapable of producing quality seeds thatharnesshighergrowthandsurvivalrates.

Until now, Indian shr imp hatcher iesimported such brood stock from the USA,Thailand and Singapore, resulting in highshipping costs and big transit losses.Theaverage cost of brood stockwas estimatedatRs5,000.

It is estimated that 80 percent of India’sshrimpfarmersaresmallscale-thequalityofseeds largelyaffects theircropsuccess.Duetothehighcosts,somehatcherieshavebeensourcing brood stock from shrimp ponds,whichultimatelyresultsintheproductionofpoorqualityseedsandsubsequentcroplosstofarmers.

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Cause of EMS detected

The pathogen whichcausesearlymortalitysyndrome (EMS) hasbeen identified by

researchers at the UniversityofArizona,USA.

A research team led byDonaldLighterfoundthatEMS,or more technically known asacutehepatopancreaticnecrosissyndrome (AHPNS), is causedby a bacterial agent, which istransmittedorally,colonizestheshrimpgastrointestinaltractandproducesatoxinthatcausestis-

suedestructionanddysfunctionof the shrimp digestive organknownasthehepatopancreas.

Thediseasewasfirstrecord-ed in China in 2009 and hassincespreadtoVietnam(2011),Thailand (2012) and Malaysia(2012). EMS kills shrimpbetween 10-40 days after thepost-larvalstagewithmortalitiesof up to 70 percent. Shrimpthat survivesuffer fromstuntedgrowthandtaletwiceaslongtoachievesignificantgrowout.

The economic impact ofEMS is perhaps yet to befully felt. However, the dis-ease is one of the most sig-nificant reasons in the fall inThai shrimp production. In2010, the country produced600,000 toms of shrimp butby 2012, this figure has fallento 500,000 tons, a drop ofaround18percent.

Lightner’steamidentifiedtheEMSpathogenasauniquestrain

of a relatively common bac-terium, Vibrio parahaemolyticus,thatisinfectedbyavirusknownas a phage, which causes it torelease a potent toxin. A simi-lar phenomenon occurs in thehumandiseasecholera,whereaphagemakestheVibrio choleraebacteriumcapableofproducingatoxinthatcausescholera’slife-threateningdiarrhea.EMShow-ever,isnotadangertopeople.

Research continues on thedevelopment of diagnostictests for rapid detectionof theEMS pathogen that will ena-ble improved management ofhatcheries andponds, and helpleadtoalong-termsolutionforthedisease. Itwillalsoenableabetterevaluationofrisksassoci-atedwith importationoffrozenshrimp or other products fromcountriesaffectedbyEMS.

Some countries have imple-mentedpoliciesthatrestricttheimportation of frozen shrimp

or other products from EMS-affected countries. Lightnersaid frozen shrimp likely posea low risk for contaminationof wild shrimp or the envi-ronment because EMS-infectedshrimp are typically very smalland do not enter internationalcommerce. Also, his repeatedattemptstotransmitthediseaseusing frozen tissuewereunsuc-cessful.

Inanefforttolearnfrompastepidemics and improve futurepolicy, the World Bank andthe Responsible AquacultureFoundation, a charitable edu-cation and training organisa-tion founded by the GlobalAquaculture Alliance, initiatedacasestudyonEMSinVietnamin July 2012. Its purpose wasto investigate the introduction,transmission and impacts ofEMS, and recommendmanage-ment measures for the publicandprivatesectors.

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Application of isotopic techniques to assess the nutritional performance of macroalgae in feeding regimes for shrimp

by Julián Gamboa-Delgado PhD, research officer, Programa Maricultura, Universidad Autónoma de Nuevo León, Mexico

Due to their nutritional prop-erties, several species ofmacroalgae have been used asdietarysupplementsforshrimps

andothermarinespecies.Sincemacroalgaerepresent a natural source of nutrients inthe shrimp’s natural environment, attemptshave been done to co-culture macroalgaeandshrimps.

The nutritionalperformanceand digestibil-ityofmacroalgae-derived mealshave been testedinformulateddietsforshrimp.Oneoftheaspects requir-ingfurtherresearchis represented bythe lossofnutritionalproperties occurringwhen the macroalgalbiomass is dried out ascompared when the algalbiomass is ingested as livebiomass.

Several nutritional method-ologies havebeen used to evalu-ate the performance of differentingredients used or proposed foraquaculturefeeds.Theuseofstableisotopesas tools toassessnutritionalcontributionsofspecificingredientstogrowthisoneofmanyemerging nutritional techniques applied inaquaculture.

The chemical composition of macroalgaevariesamongspeciesandenvironmentalcon-ditions;however,mostarerichinnon-starchpolysaccharides, vitamins, and minerals. Inparticular, green macroalgae (Chlorophyceae)oftenhavehigherproteincontentthanbrownseaweeds.Suchnutritionalproperties,incon-junction with novel macroalgae productionmethods,have increasedthe interest intheiruse as dietary ingredients for aquaculturediets.Additionally,therearestudiesthathavefocusedontheiruseasadditivestoenhancetheimmunologicalstatusofthefarmedanimals.The green macroalgae Ulva (Enteromorpha) clathrata, also known as aonori in Asiancountries,hasworldwidedistributionanddueto its nutritional profile, has been evaluatedas a dietary supplement for aquatic species.U. clathratahasbeenmass-culturedinrecent

yearsunderapatentedtechnologydevelopedby Aonori Aquafarms Inc. By applying thismethodology, macroalgae biomass is rapidlygrown in pondswithout eliciting detrimentaleffectstotheenvironment.

Evaluation of macroalgae in shrimp nutrition studies

Althoughithasbeenobservedthatuseofmacroalgal biomass alone as feed does notfulfil thenutritional requirements foroptimalgrowth in marine shrimp, co-culture of U. clathrataandPacificwhiteshrimpL. vannameihas been conducted with positive results intermsof lower feedutilizationand improve-ment of the shrimp nutritional quality, fleshcolourandtexture.

Recentnutritionalstudieshavealsoshownthat when dry Ulva clathrata meal is fedto Pacific white shrimp as an ingredient inpractical diets, it has an apparentdigestibilitycoefficientfordrymatterof83percent,whilethe same value for protein is 90 percent.However,thehighashcontentandtherela-tivelylowproteincontentofthismacroalgaespecies prevent its dietary inclusion at highlevels when attempting to replace otheringredientssuchasfishmeal.

Stable isotopes to assess the nutritional contribution of macroalgae

Over the last few decades, different iso-topicmethodologieshavebeenadoptedfromtheecologicalsciencesandhavebeenappliedtoanimalnutritionstudies.Mostelements inorganic matter are present as two or morestable isotopes and heavier isotopes havea tendency to accumulate in animal tissue.For example, animal predators have higherisotopic values than their preys; therefore, aspecificisotopicsignatureisconferredtoeach

Table 1: Growth, survival rate and estimated consumption of formulated feed and live macroalgae biomass (dry weight) by juvenile litopenaeus vannamei reared on five different feeding regimes for 28 days (n= 8-20, mean values ±SD)

Feeding regime Survival (%) Final wet

weight (mg)Weight

increase (%)

Consumed formulated feed (g)

Consumed U. clathrata

(g)

100F 95 ± 13a 995 ± 289a 429 0.94 -

75F/25U 93 ± 11a 1067 ± 364a 467 0.81 0.40

50F/50U 78 ± 11ab 768 ± 273ab 308 0.43 0.44

25F/75U 60 ± 21b 424 ± 207b 125 0.14 0.65

100U* 23 ± 4c 221 ± 49c 18 - 1.32

Initial wet weight = 188 ±28 mg

Different superscripts indicate significant differences at p<0.05

* Parameters in animals from feeding regime 100U were estimated on experimental day 21

Juvenile Pacific white shrimp feeding on U. clathrata

macroalgal biomass. Long fecal strands are frequently related

to fast gut transit

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May-June 2013 | InternatIonal AquAFeed | 49

trophic level (primary producers, herbivores,carnivores).

Inthecaseofplantsandmacroalgae,theircarbonisotopevaluesarestronglyinfluencedby the type of photosynthesis they present.On the other hand, the nitrogen stable iso-topevaluesofplantsandmacroalgaecanbeeasilymanipulatedbymeansofspecificfertilis-ers,toeventuallyconductnutritionalstudies.

Byusingsuchtechniques,itcanbepossibleto determine the proportions of availabledietary nutrients that have been selected,ingested and incorporated into animal tis-sue (Figure 1). As the average sample sizerequired for stable isotope analysis (carbonand nitrogen) is only 1 mg of dry tissue ortestdiet,thetechniquehasbeenveryusefulinlarvalnutritionstudies. Ithasbeenemployedtoquantifytheproportionsofnutrientsincor-poratedfromliveandformulatedfeedsinfishandcrustaceanlarvae.

Likewise, stable isotope analyses of dif-ferent plant-derived ingredients (soy proteinisolate,cornglutenandpeameal)havebeencarriedouttoexplorethecontributionofthedietarynitrogensuppliedbythesesources(ascomparedtofishmeal)toshrimpgrowth. Inthecontextofmacroalgaeassourceofnutri-ents, isotopic techniques have been appliedas nutritional tools to quantify the relativecontributionsof dietary carbon andnitrogentothegrowthofPacificwhiteshrimpco-fedformulated feed and livemacroalgal biomassofU. clathrata.

Experimental design

Taking advantageof the contrast-ing natural carbonand nitrogen stableisotope values meas-uredinacommercialformulated feed andinlivemacroalgalbio-mass of U. clathrata,the study aimed toquantify the relativecontributionofnutri-entstothegrowthofPacific white shrimp.Animalswereallocat-edtoduplicate tanksindividually fittedwithair liftsandconnectedtoanartificial-seawaterrecirculationsystem.

Feeding regimes consisted of a positiveisotopic control (100% formulated feed,treatment100F),anegative isotopiccontrol(100% macroalgae, treatment 100U) andthree co-feeding regimes in which 75, 50,and25percentofthedailyamountofcon-sumed macroalgal biomass was substitutedby formulated feed (treatments 75F/25U,50F/50U, and 25F/75U, respectively) on adryweightbasis.

The digestibility of both feeding sourc-es for L. vannamei has been previouslyassessed and is similarly high (>80%).

Live macroalgae was supplied to shrimpby attaching the algal biomass to plasticmesh units from which the algal filamentswereconstantlyavailableandeasilynibbleduponbyshrimp.

Feedingrationsandproportionswerepro-gressively adjusted in relation to theamountofmacroalgalbiomassconsumed,animalsur-vival and sampling. Shrimp samples (wholebodies and muscle tissue) and diet sampleswere collected and pre-treated for isotopicanalysis.

Growth and survivalThere was a high variability in final wet

Figure 1: Carbon and nitrogen flow in shrimps produced under semi-intensive farming conditions. Bold arrows

indicate components that can be isotopically analyzed to determine their origin and fate


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weightofshrimpsunderthedifferentdietarytreatments; however, a clear tendency forhighergrowthwasobservedinshrimpsrearedon regime 75F/25U (1,067 ±364 mg, finalmean weight), followed by shrimps fed onlyonformulatedfeed(995±289mg).Shrimpsfrom both feeding regimes increased theirweightmorethan400percent(Table1).

Animals fed only on U. clathrata bio-mass showed very low growth (221 ±49mg) and only 23 percent of the animals inthis treatment survived by day 21. Highersurvival rates (93-95%) were observed inshrimpsrearedonfeedingregimes100Fand75F/25U,whileshrimpsindietarytreatments50F/50Uand25F/75Uhadrespectivemean

survival rates of 78 and 60percent. The positive effectof supplying both, live feedsandformulateddietshasbeenrecurrentlyobserved inprevi-ouscrustaceanstudies.

Dietary contributions from macroalgae and formulated feed

At the end of the experi-ment,isotopicvaluesofshrimptissue reared on co-feedingtreatments were stronglybiased towards the isotopicvaluesofU. clathratabiomass.

Figure 2 combines carbonand nitrogen stable isotopevalues measured in shrimpsand provides a graphic indica-tionofthetotalorganicmattercontributed by both, the for-mulated feed and macroalgae.Resultsfromanisotopicmixingmodelindicatedthatshrimpsinthe three co-feeding regimesincorporatedsignificantlyhigheramountsofdietarycarbonand

nitrogenfromU. clathratabiomassthanfromtheformulatedfeed(Table2).

Attheendof theexperiment,shrimps intreatment 75F/25U incorporated68percentof carbon from the formulated feed and 32percentfromthemacroalgae.Shrimpsunderfeedingregimes50F/50Uand25F/75Uincor-poratedsignificantlyhigheramountsofdietarycarbonfromU. clathrata(49and80%,respec-tively) when compared to the expecteddietarycarbonproportionssuppliedbythesetheco-feedingregimes(34and70%,respec-tively). Shrimp grown in co-feeding regime75F/25Uincorporated27percentofnitrogenfrom the formulated feedand the remaining73 percent from the macroalgal biomass,whileanimalsrearedonregimes25F/75Uand50F/50U incorporated the majority of theirdietary nitrogen (98 and 96%, respectively)fromthemacroalgae.

The lower growth attained by these ani-mals indicatedthataveryhighproportionoftheisotopicchangewasduetohighnitrogenmetabolic turnover and not to tissue accre-tion. Due to its lower carbon and nitrogencontents, the macroalgal biomass had to beconsumedathigheramountsinordertosup-ply the observed elemental contributions toshrimpwholebodiesandmuscletissue.

The availability and incorporation of nutrients from formulated and live feeds

The higher than expected contributionsofmacroalgalcarbonandnitrogentoshrimpgrowth are possibly related to the highdigestibilityofU. clathrata and its continuousavailabilityforshrimp.ChemicalanalysesofU. clathratahaveshownthatittypicallycontainslowtomediumproteinlevels(20-30%)andvery low lipid levels. The cell wall polysac-charidesinmacroalgaemightrepresentmorethan half of dry algal matter, but a tentativeroleofthelatterasenergysourceisunlikelyasspecificenzymaticactivitiesforthesepolysac-charides (ulvanase, fucoidanase) have notbeen reported for Penaeid shrimps. Despitetheir lower nutrient concentration, live feedcontainshigherwatercontentwhichcontrib-utestohigherdigestibility.

In contrast, formulated feed can contributenutrients that are scarce or absent in live feed,buttheincorporationofsuchnutrientsislimitedbylowfeeddigestibilityorunsuitableformulation.Previous co-feeding experiments conducted onpostlarval shrimp and larval fish have shownthatthesuppliedlivefeedfrequentlycontributeshigherproportionsofnutrientstothegrowthofthe consuming animals than those supplied byformulatedfeedsinco-feedingregimes.

ConclusionAlthoughthelivemacroalgaebyitselfwas

not nutritionally complete for Pacific whiteshrimp, it supplied a very significant propor-

Table 2: estimated contribution of dietary nitrogen supplied from formulated feed and live biomass of Ulva clathrata and incorporated in tissue of postlarval Pacific white shrimp L. vannamei as indicated by stable isotope analysis.

Feeding regime expected* observed

Whole bodies

Muscle tissue

75F/25U

Formulated feed 79.6a** 15.9 b 20.5 b

Ulva biomass 20.4 84.1 79.5

50F/50U

Formulated feed 66.1a 2.2 b 6.9 b


25F/75U

Formulated feed 30.1a 1.0 b 3.2 b


*Expected proportions are estimated from the actual proportions of formulated feed and macroalgal biomass offered (on a dry weight basis)

**Superscripts indicate significant differences between expected and observed dietary contributions

Figure 2: Carbon and nitrogen dual isotope (‰) plot of whole bodies and muscle tissue of white shrimp L. vannamei reared on feeding regimes consisting of different

proportions of formulated feed and live U. clathrata biomass. Muscle tissue values for treatment 100U were estimated for day 28 from values in whole bodies. n= 2-4,

mean values ±SD


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tion of structural carbon and nitrogenwhenco-fedwithformulatedfeed.

However, the high amount of nutrientsderived from the livemacroalgaebiomass inco-feeding regimes supplying more than 50percentofmacroalgae,wasnotreflectedinafastgrowthincrease.Thiswaspossiblyduetotherestrictionofothernutrients inthismac-roalgae species. Interestingly, shrimp underthe co-feeding regime supplying 75 percentof formulated feed and 25 percent of livemacroalgae biomass showed higher growthratesthananimalsrearedonlyoncommercialformulated feed,althoughthedifferencewasnotstatisticallysignificant.

Thelowlevelsofenergy,aminoacidsandfatty acids in the macroalgae biomass avail-able to shrimp, were compensated throughhigh ingestion rates, which caused a higherincorporation of nutrients in shrimp tissue.On the other hand, it is very likely that thecarbohydrates and lipids supplied by theformulated feed significantly contributed totheenergyrequirementsofshrimpunderthethreeco-feedingregimes.

Theimportanceofthenaturalproductivitytoshrimpgrowninsemi-intensivelymanagedpondshas been widely documented. The systematicuseofmacroalgaeinproductionpondsnotonlyprovidesasignificantnutritionalsupplytoculturedorganisms,butalsoofferssubstrateforperiphyton

growthandrefugeformoultingshrimps.Inaddi-tion,ithasbeendemonstratedthatUlva clathrataandothermacroalgaespeciesareefficientremov-ers of the main dissolved inorganic nutrients,hence maintaining good water quality levels inaquaculturepondsandeffluents.

Diverseisotopictechniquescanbeappliedtoelucidatethetransferofnutrientsatthelevelofaminoacidsandfattyacids;therefore,futureexperimentalassaysmightrevealwhatspecificnutrientsarecontributed fromthemacroalgalbiomass(oranyothercomponentofthenatu-ral biota) and from the supplied formulatedfeeds.The lossof somenutritionalpropertiesthatoccursindietaryingredientsthatundergodrying (or freeze drying) has not been thor-oughly explained and future studies applyingstable isotopesmight shed some lighton thedifferences observed when aquatic animalsconsumemoistordrydietarycomponents.

References

Burtin,P.2003.Nutritionalvalueofseaweeds.Electron.J.Environ.Agric.FoodChem.2:498–503.

Cruz-Suárez,L.E.,A.León,A.Peña-Rodríguez,G.Rodríguez-Peña,B.Moll,D.Ricque-Marie.2010.Shrimp/Ulvaco-culture:asustainablealternativetodiminishtheneedforartificialfeedandimproveshrimpquality.Aquaculture301:64–68.

Gamboa-Delgado,J.2013.Nutritionalroleof

naturalproductivityandformulatedfeedinsemi-intensiveshrimpfarmingasindicatedbynaturalstableisotopes.ReviewsinAquacultureInpress.

Gamboa-Delgado,J.,M.G.Rojas-Casas,M.G.Nieto-López,L.E.Cruz-Suárez2013.Simultaneousestimationofthenutritionalcontributionoffishmeal,soyproteinisolateandcornglutentothegrowthofPacificwhiteshrimp(Litopenaeus vannamei)usingdualstableisotopeanalysis.Aquaculture380-383:33-40.

Gamboa-Delgado,J.,A.Peña-Rodríguez,L.E.Cruz-Suárez,D.RicqueD.2011.AssessmentofnutrientallocationandmetabolicturnoverrateinPacificwhiteshrimpLitopenaeus vannameico-fedlivemacroalgaeUlva clathrataandinertfeed:dualstableisotopeanalysis.J.ShellfishRes.30:1–10.

Moll,B.(SinaloaSeafieldsInternational).2004.Aquaticsurfacebarriersandmethodsforculturingseaweed.Internationalpatent(PCT)no.WO2004/093525A2.November4,2004.

Villarreal-CavazosD.A.2011.Determinacióndeladigestibilidadaparentedeaminoácidosdeingredientesutilizadosenalimentoscomercialesparacamarónblanco(Litopenaeus vannamei)enMéxico.PhDThesis.UniversidadAutónomadeNuevoLeón,Mexico.http://eprints.uanl.mx/2537

More InforMatIon:Julián Gamboa-Delgado PhD Tel: +52 81 8352 6380Email: [email protected]


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also stimulate digestive enzyme production(Cahuetal.1998).

Production of microalgaeDespitethemanyadvantagesofmicroalgae,

their wider use is hampered by difficulties inculturing, storage, and high costs. Microalgaeculturecanconsumeasignificantfractionoftheresources of a hatchery, and requires specialequipment, skilled labour, and a large alloca-tion of space that is unproductive during theseasonswhenlivefeedsarenotneeded.

Low-cost open-pond culture methodscarryhigh risksof contaminationandculturefailuredue to the impossiblityof tightlycon-trollingcultureconditions,andthemosthighlyprizedhigh-PUFAstrainssuchasIsochrysisandPavlovarequireindoorculture.

Itisverydifficulttosynchronizemicroalgalproduction with live feed requirements toprevent feed shortagesorwasteful overpro-duction, and it is difficult to accurately dosealgae cultures directly into live feed cultures.If the algae are harvested and concentrated,thetightly-packedcellscandeterioraterapidlyinrefrigeratedstorage.Somemicroalgaehavebeen freeze- or spray-dried, but dried cellsaresubjecttoproteindenaturation,andwhenthey are rehydrated the leaching of water-soluble substances can rapidly deplete theirnutritionalvalue,aswithotherdryfeeds.

Microalgae concentratesThe best solution to these problems

can be the use of commercially-availablerefrigerated or frozen algae concentratesor ‘pastes’ (Guedes & Malcata 2012,Shields&Lupatsch2012).Theseproducts,which are actually viscous liquids, haveproven to be effective feeds for rotifers,Artemia, shellfish and other filter-feeders,aswellasforgreenwaterapplications.

In products formulated to provide alongshelf-life,theconcentratedmicroalgaeare suspended in buffer media that pre-servecellularintegrityandnutritionalvalue,although the cells are non-viable. Whenconcentrates with well-defined biomassdensities are employed, the algae can beaccurately dosed into live feed cultureswith a metering pump, and non-viabilityconfers the advantage that the productspose no risk of introducing exotic algalstrains.Thebestrefrigeratedproductstypi-cally have a shelf-life of 3-6 months, andfrozenproducts several years.Thismeansthatareliablesupplyofalgaecanbekeptonhand,availableforuseinanyseasonorif an unexpected need arises. Algae costsbecome predictable, and often prove tobelessthanon-siteproductionwhentotalproduction costs and inefficiencies areaccountedfor.

Although costs of liquid algae concen-trates are higher than for dried algae orformulatedfeeds,theyofferallthenutritionaladvantages of live cultures. The nutritionalquality of live feeds can be no better thanthe food sources used to produce them.Success of early larvae is so critical to thesuccess of a hatchery that even a relativelysmallimprovementinsurvivalorgrowthratecanyieldgreatbenefits.

OutlookLive feeds remain indispensable for

larviculture of many fish. Although micro-algaeareamongthecostliestfoodsourcesused to produce live feeds, their manyadvantages justify the cost for hatcheriesproducinghigh-valuefish.Researchcontin-ues to better characterise the nutritionalproperties of various algae strains and tooptimise algae production technologies.We can anticipate that introduction ofnovel algae strains and nutritionally-opti-mised combinations of strains, along withimproved feeding protocols, will ensurethatmicroalgaeremainthefoodofchoicefor production of the highest-quality livefeeds.

Referenceswww.aquafeed.co.uk/referencesIAF1303


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16

INTERNATIONAL AQUAFEED DIRECTORY 2012/13

SCIENCE DFO SCIENCE SCIENCE

Saltwater mariculture-aquaculture inQuebec may soon welcome a newarrival: the Spotted Wolffish, a threatened and little-known species thattastes delicious.In Quebec, commercial fish farms currently limit themselves to farmingfreshwater fish, while the maricultureindustry has focused until very recentlyon molluscs. In other parts of the world,saltwater fish farms are located right inthe ocean. Doing so significantly reducesfarming costs and makes them profitable. In Quebec, installing aquaculture equipment in the ocean is adicey prospect because of ice cover inwinter. Previously, experiments withfarming saltwater fish in tanks revealedthe need for technical expertise as wellas the high cost of production. Today,however, research advances are showingthe potential of the Spotted Wolffish.This new mariculture candidate wasfirst noticed in the early 2000s. At thetime, teams from the Maurice-Lamontagne Institute in Mont-Joli,Quebec, collected their first SpottedWolffish as part of the research projectsthey were conducting with the

Université du Québec à Rimouski andthe Quebec ministry of agriculture, fisheries and food.First of all, the Spotted Wolffish is afish that adapts well to the conditions itis kept in and is easy to domesticate. Itdevelops quickly at very low temperatures and is not very sensitive tochanges in the salinity of the water.Spotted Wolffish can be farmed in highdensities, something that is crucial forthe profitability of an aquaculture operation (see Figure 2). As well, eventhough the Spotted Wolffish does notreproduce spontaneously in captivity,new generations can be produced everyyear using captive broodstock. And let’snot forget another important quality thisfish possesses: it tastes great. Aside from these obvious advantages,it is important to find out how thisspecies grows in captivity so that itspotential benefit to Quebec’s aquacultureindustry can be properly assessed. Forthat reason, Denis Chabot, a researcher atthe Maurice-Lamontagne Institute, wasapproached by the Société de développement de l’industrie maricole(SODIM) to carry tests using water tanks.

The studies were also conducted in theresearch centre’s aquaculture facilities,which allowed the farming to be done ona large scale. This zootechnical demonstration, the final results of whichwill be known sometime in 2011, wascarried out in collaboration with NathalieLe François, a researcher at the Biodômede Montréal and associate professor atthe Université du Québec à Rimouski. The first wolffish, hatched at the endof fall 2008 in the Centre aquacole marinde Grande-Rivière, were delivered to theMaurice-Lamontagne Institute in May2009. Since their arrival in the tank,these roughly 400 fish have been handled very carefully. Every month, theresearchers measure their growth rate, inconditions kept as close as possible tothose found in commercial fish farmingoperations. These measurements arecompared with data gathered in Norwayand Iceland, where Spotted Wolffishhave been raised for experimental andcommercial aquaculture for about 10years now. Preliminary results fromMont-Joli show a growth rate that isslightly less than that observed inNorway, a country that has had considerable experience in farming thespecies; thus, rearing conditions at theMaurice-Lamontagne Institute still havesome room for improvement. Feeding poses one of the biggest challenges for obtaining optimal growthin farmed Spotted Wolffish. The commercial feed used until now wasintended for salmonids and has not beenmodified. The feed has too much fat andwolffish that are fed this type of food tendto develop liver abnormalities.Researchers also question whether itoffers enough protein for the particularneeds of the species. Another problem:the feed does not float and sinks to thebottom of the tank, which is problematicwhen it comes to feeding fish speciesraised in high densities. Ideally, the feed

Farming saltwater fish in Quebec:The Spotted Wolffish shows promise

Figure 2: Spotted Wolffish in farming tankPhoto: Arianne Savoie, Fisheries and Oceans Canada

pg16_DFO_wolffish.qxd 24/8/12 12:30 Page 16


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They are what they eat Enhancing the nutritional value of live feeds

with microalgae

Controlling mycotoxins with binders

Ultraviolet water disinfection for fish

farms and hatcheries

Niacin – one of the key B vitamins for sustaining

healthy fish growth and production

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