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Producing Tilapia in Small Cage in West AricaTechnical manual prepared or the Project:

Improved fsheries productivity and management in tropical reservoirs,

CP-PN34: Challenge Program on Water and Food

www.worldfshcenter.orgReducing poverty and hunger by improving www.worldfshcenter.orgReducing poverty and hunger by improving fsheries and aquaculture

MANUAL | 1952

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Producing Tilapia inSmall Cage in West Africa

JK Oori

HR Dankwa

R Brmmett

EK Abban

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Al l rights reserved. This pblicat ion ma not be reprodced in whole or in part or

edcational or non-proit prposes withot permission i de acknowledgement

is given to the copright holder. This pblication ma not be reprodced or proit

or other commercial prposes withot prior written permission rom the

pblisher.

Water Research Institte, P.O.Box AH 38, Achimota, Ghana

This pblication shold be cited as:

JK Oori, HR Dankwa, R Brmmett and EK Abban. 009. Prodcing Tilapia in

Small Cage in West Arica. WorldFish Center Technical Manal No. 95. The

WorldFish Center, Penang, Malasia. 6 pp.

JK OoriHR Dankwa

R Brmmett

EK Abban

009 The WorldFish Center

Pblisher: Water Research Institte,

P.O.Box AH 38,

Achimota, Ghana

Printer: The WorldFish Center,

Penang, Malasia.

Cover photograph: EK Abban

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Contents

Prc tapa sa Ca W Arca 5

Water Research Institte 5

Cage Constrction and Placement 5

Stocking 7

Feeding & Growth 9

Harvesting & Marketing 0

Proitabilit 3

Technical Smmar 4

s Ra 16

Acw 16

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PRoduCing tilAPiA in smAll CAges in West

AfRiCA1

WATER RESEARCH INSTITuTE

Fish cages bilt rom locall availablematerials and stocked with local sh thatare ed local eeds are sed or tilapiaaqacltre in Arica, prodcing abot6,000 tonnes per ear at bigger arms inCte dIvoire, Ghana, Malawi, uganda andZimbabwe. Reported ield varies between50 and 50 kilograms (kg) per cbic metre

(m3) per 9 months. In Ghana, positive cashfows have been reported or arms thatachieve otpts averaging 0 tonnes permonth throghot the ear. The WaterResearch Institte (WRI) in Akosombo,Ghana, is working to bring cage aqacltretechnolog to smallholder armers. Thestocking, eeding and cage-constrctiontechnolog piloted b WRI is now being

widel adopted in the Lower Volta basin inGhana. The reslts o WRI research overthe period 005-009 are presented hereas a gide to potential investors.

CAGE CONSTRuCTION AND PLACEMENT

Cages can sometimes be prchased locall. An alternative is to bild one singthe 5 millimetre (mm) mltilament stretched mesh netting tpicall sed in

beach seine sheries. This material is ct to size and sewn together with heavnlon thread to orm a basket. The tpical size sed in Volta Lake is abot 64metres on the sides and metres deep, or a volme o 48 m 3. Deeper cageshave been tested bt do not seem to increase prodction. The net basket isthen attached with nlon twine to a pipe rame boed b oil drms, or plasticbarrels originall sold containing paint or alcohol, both readil available on themarket. A cover placed on top o the cage is essential to prevent bird predation.

Consltative Grop on International Agricltral Research (CGIAR) Challenge Program on Water and FoodProject 34: Increasing Fish Prodction rom the Volta Lake.

An agenc o the Concil on Scientiic and Indstrial Research, PO Box M3, Accra, Ghana.

th War Rsarch is Akosombo, ghaa, s work obr ca aqaclr choloyo smallholr armrs.

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Decking bolted onto the metal ramemakes eeding and working arondthe cage easier.

Cages shold be anchored in at

least 8-0 metres o water. The bestanchoring sstem comprises or0.3 m3 concrete blocks, into eacho which is cemented a 6.4 mm(/4) iron loop tied to ropes thatare connected to each corner o thefoating cage ramework rom whichthe cage was sspended. The costo the cage is shown in Table .

tabl 1. Ca cosrco coss s locally avalabl maralsa

Item Description Quantity Unit cost

()bItem amount

()b

Galvanized pipe .5- 8 6

Floats Plastic barrel (50 litre) 8 30 40

Nets 5 mm stretched mesh 40 metre 4.375 75

Shackles 6 3 48

Hapa nets 40 metre 0.5 00 50

Rope0 mm diameter

6 mm diameter

coils

coil

0

5

0

5

Anchors 0.3 m3

6 5 30

Welding 50 50

Cage cover net 65 metre

Labor 30 30

Total 876m3 cbic metre, mm = millimetre.

a

For a 48m3

aqacltre cage manactred rom materials locall available in Ghana.b Ghanaian cedi ( = uS$0.89).

n cas boy by plasc barrls alas 8-10 mrs o war.

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STOCKING

Fingerlings weighing 0-30 grams (g) are available rom several hatcheries among them Tropo Farm, Crstal Lake, Fish Reit, Anson-Greenelds and roma selected line oOreochromis niloticus prodced at the Ghanaian AqacltreResearch and Development Centre in Akosombo. These grow some 0-5%aster than the local wild stock. Prices range rom 0.0 to 0.5 or mixedmales and emales and p to 0.-0.0 or all males. The advantage o sing

all males is that the grow abot 40% aster than mixed sexes when prodcingsh o over 50 g.

Fingerlings can be stocked at rates ranging rom 3,000 to 9,000 sh per 48 m3o cage (63-88 sh/m3). Extreme care mst be taken in transporting, holdingand handling ngerlings to avoid heav mortalit. Fingerlings need to be keptcool and in clean reshwater. Thewater temperatre in the transportcontainer and the cage shold be

the same. Fingerlings shold notbe toched more than is absoltelnecessar.

Once in the cage, dead sh ondfoating shold be removed dailand recorded. The rle o thmbis that or ever dead sh ondfoating, two dead sh sank. Ths,three times the nmber o sh ondfoating dead dring the rst week

dal o ca cosrco showwl bracks orm h ram.

dal show oa a caaachm.

dck aach wh u-bols o hmal pp ram aclas work

aro h ca.

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are stocking mortalities and shold be replaced with new ngerlings. Mortalitiesoccrring later shold be noted or the prposes o calclating the eeding rate(see below) bt not replaced, as replacement wold mostl increase variabilitin the harvested poplation.

r 1: growh o mx sx lapa 4 cas ovr 6 mohs

r 2. growh o all-mal lapa 6 cas ovr sx mohs

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a fsh ca wh mpor oa pll s. no h voros rspos ca halhy fsh.

FEEDING & GROWTH

Fish in cages shold be ed with pelleted sh eed containing approximatel8-3% crde protein. Optimal eeding reqires that smaller sh receivesomewhat higher protein levels, bt these eeds are not generall available inthe region at this time. Fish were ed at a declining rate o 0% down to %o estimated average bodweight based on the monthl average weight o a

sample o at least 50 sh rom each cage (Table ).

tabl 2: rm s pll fsh or lapa clr cas

Fish average weight (grams) Feed applied daily (% of body weight)

5-0 0.0-7.0

-50 7.0-4.0

5-00 4.0-3.5

0-50 3.5-.5

5-450 .5-.0

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3 As these prices change reqentl, estimates o proitabilit shold be redone prior to each prodction cclebased on a carel analsis o crrent prices or both inpts and otpts.

th avaa o s all mals s ha hy row abo 40% asr ha mx sxswh proc fsh o ovr 250 rams.

The total dail ration shold be divided over -3 eedings administered b hand,sing either foating or sinking eed. Floating eed is sall more expensivethan sinking bt acilitates monitoring the eeding response.

The eed conversion ratio (FCR) is the amont o eed reqired to prodce kg o

sh; the lower the FCR, the better. The FCR in tilapia cage aqacltre sstemsin Arica is tpicall between .4 and .5. An FCR higher than normal can bethe reslt o a high percentage o nes (eed dst) in the eed, variabilit in thereported ntrient content o the eed and/or a miscalclation o the nmber osh remaining in the cage becase o nrecorded mortalit.

HARVESTING & MARKETING

The target size or sh in most o West Arica is between 300 and 500 g. With

good management, this size can normall be reached in 5-7 months (Figre 3).Wholesale prices in Ghana var according to size class. Fish weighing >300 gsold or 3.50 Ghana cedis () (uS$3.) per kg, sh weighing 50-300 g sold or.80 ($.49) per kg, and sh weighing

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with cage cltre. Another cage wasdamaged when it became oledwith a sbmerged tree when thewater level was low and then rippedopen when the water level rose

again, releasing the sh. Srvivalwas low in all cages, averaging 30%among those that were not damagedor robbed. This was mostl the reslto poor sh conditioning, handlingand transport dring stocking (seeStocking section above).

tabl 3: sh sock, rowh a harvs aa (frs plo ral)a

Cage 1 Cage 2 Cage 3 Cage 4

Date stocked 006 7 October 08 December 3 October 3 October

No. stocked 4,000 6,000 7,000 ,780

Average weight at stocking (g) 3.4 0.3 5.0 4. .9 8.0 3.7 5.0

Average weight at harvest (g) 07.5 60.0 77.5 4.4 9.7 88.3 307.5 34.

Grow-ot (das) 53 47 33 5

Biomass GR (kg/da) .69 9.05 7. 4.4

No. sh at harvest ,946 4,639 ,079 ,647

Srvival (%) 48.7 77.3 5.4 59.

Specic GRb

.79 .64 .3 .49

FCR .64 .50 3.5 .97

Gross ield (kg/cage) 34.7 ,75.7 47. 40.5

Net ield (kg/cage) 70.9 ,05.7 .3 34.3FCR = eed conversion rate, g = gram, GR = growth rate, kg = kilogram, m3 = cbic metre, No. = nmber.

a Nile tilapia grown in 48 m3 cages and ed with sinking eed or 6 months in Volta Lake, Ghana.

b Specic growth rate (%/da) is the average nal weight o individal sh mins the average initial weight,

the dierence div ided b the nmber o das in the growth period.

27%300g

r 3: tlapa harvs rom casar 6 mohs by sz, a szcaors % h harvs

54%

19%

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The srvival rate in smallholder tilapia cage cltre is tpicall in the range o 70-80%, thogh srvival rates as low as 60% have been associated with stockingdensities in excess o 70 sh per m3. WRI and other hatcheries have, sincethese trials, developed improved conditioning and transport methods that haveredced stocking mortalit to less than 0%.

tabl 4: sh sock, rowh a harvs aa (sco plo ral)a

Cage 5 Cage 6 Cage 7 Cage 8 Cage 9 Cage 10

Datestocked007

3 Jan. 6 Jl 7 March 3 Agst 8 Jl 7 Jl

No.

stocked

7,500 8,00 7,500 9,000 6,000 6,000

Averageweight atstocking (g)

.9 9.8 .9 8.8 .45 4.9 .5 4.9 0. 9.3 0. 9.3

Averageweight atharvest (g)

369.7 55.5 45. 30.3

Net tornopen onbottom;

last sampleon 0 Jan

008,averageweight38 g

Netslashed b

shers;last

sample on5 Oct007,

averageweight86. g

Poisonedb shers;

lastsample on

3 Dec007,

averageweight84 g

308. 4.

Grow-ot(das)

69 47 30

No. sh atharvest

480 53 54

Srvival (%) 0 6.4 5.7

SpecicGRb

.7 .03 .

FCR .6 .5 8.

Gross ield(kg/cage) 34.7 3 503.4

Net ield(kg/cage)

70.9 44.4 389.7

FCR = eed conversion rate, g = gram, GR = growth rate, kg = kilogram, m3 = cbic metre, No. = nmber.

a Nile tilapia in 48 m3 cage aqacltre at Dzemeni in Stratm II o the Volta Lake, Ghana.

b Specic growth rate (%/da) is the average nal weight o individal sh mins the average initial weight,and the dierence divided b the nmber o das in the growth period.

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PROFITABILITy

Feed costs averaged 5% o total prodction costs.

Onl cage , rom which more than tonne o sh was harvested (>96 shwith a combined weight o 4.5 kg per m3), made a signicant prot (Table5). FCRs were between .5 and 8., averaging 3.54 (Table 3). Feed was themajor component o cost, averaging over 50% o the total (Table 6). Fingerlingprchase was another major cost, acconting or an average o 7% o thetotal.

tabl 5. ecoomc aalyss o lapa aqaclr casa

Cage 1 Cage 2 Cage 3 Cage 4 Cage 5 Cage 6 Cage 10

Fixed costb 09.5 09.5 09.5 09.5 09.5 09.5 09.5

Variable cost ,760.7 ,700 ,458.7 ,468. ,598.0 ,867.0 ,687.0

Total cost ,870.3 ,809.5 ,568. ,577.6 ,707.5 ,978.5 ,756.5

Revene 8.8 3,57.0 74.3 ,07.5 ,36.4 8.0 ,760.

Net income -,057.4 77.5 -,86.9 -370. -574. -895.5 4.5

a Operated or approximatel 6 months in Stratm II o the Volta Lake, in Ghana ( = uS$0.89).b For the cage, amortized over 4 ears.

tabl 6: Proco coss, rvs a rr o vsm

Quantity Unit value ()b Item amount ()b

Item

Cage (amortized over 4 ears) / 9.00 09.50

Fingerlings 6,000 0. 70.00

Feed (kg) 3,000 0.49 ,470.00

Labor (person-months) 6 60.00 360.00

Marketing 50.00

Transportation 00.00

Total cost 2,809.50

Revenues

Total harvest (kg) ,76 3.00 3,58.04

Net income 718.54

Return on investment 25.6%

a Tilapia aqacltre sing a 48 m3 aqacltre cage in Stratm II o the Volta Lake, stocked at a densit o5 ish/m3, cltred or 47 das and achieving a srvival rate o 77.3%.

b Ghanaian cedi ( = uS$0.89).

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According to the data collected at Dzemeni, a minimall protable 48 m3smallholder cage aqacltre sstem in Ghana wold have to prodce at least tonne o sh at an FCR o less than .5.

TECHNICAL SuMMARy

In Ghana, cages can be bilt or prchased at a cost o approximatel $,000per 48 m3. Nile tilapia (Oreochromis niloticus) are stocked at an average rateo 03 sh/m3 and ed locall with available pelleted eeds or approximatel6 months. Total costs averaged $,038 per 6-month prodction ccle. Grossield ranged rom 3 to ,76 kg/cage, averaging 460 kg/cage (9.6 kg/m3).Mortalit, reslting primaril rom poor handling dring transport and stocking,averaged 70% and was a major constraint on prodction and protabilit. Tobreak even, the harvested biomass o sh needed to exceed 5 kg/m3. At 5kg/m3, smallholder cage aqacltre generated a net income o $77 per cageper 6 months, or a retrn on investment o 30.% on revenes o $3,500. Water

to brak v, h harvs bomass o fsh o xc 15 k/m3.

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qalit in the area srronding the cages was not compromised b aqacltreat the scale tested, in which 5 tonnes o eed was applied over 6 months.

In conclsion, aqacltre is alwas challenging, and an investment in sharming shold never be considered a sre deal. Man sh armers, large and

small, have lost mone on aqacltre. The reslts reported here show how theproblems encontered can make an enormos dierence to the bottom line. Itis normal or small bsinesses to take 3-5 ears to trn a prot, and aqacltreis no dierent.

For more inormation:

Joseph K. Ofori

Aquaculture Research & Development Centre

Akosombo, Ghana

Telephone: +33 5 0786Email: oorijkdr@ahoo.com

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suggested ReAding

Balarin JD, Haller RD. 98. The intensive cltre o tilapia in tanks, racewas and cages.

In: Mir JF, Roberts RJ (eds). Recent advances in aqacltre. London: Croom Helm,

Ltd..

Beveridge MCM. 004. Cage Aqacltre (3rd Edition). Oxord: Blackwell Pblishing,Ltd.

De La Crz-Del Mndo R, Del-Mndo P, Gorospe M, Macas R. 997. Prodction and

marketing o cage-reared tilapia (Oreochromis niloticus) in Taal Lake, Agoncillo, Batangas.

In: Fitzsimmons K (ed). Tilapia aqacltre: Proceedings rom the Forth International

Smposim on Tilapia in Aqacltre. Ithica, uSA: Northeast Regional Agricltral

Engineering Service. pp 633-64.

El-Saed AFM. 006. Tilapia cltre. Wallingord, uK: CABI Pblishing,.

Gorissen G. 99. Considrations zootechniqes et conomiqes sr llevage d Tilapia

niloticaen cages Toro (Katiola), Rpbliqe de Cte dIvoire. In:Bernacsek GM,PowlesH (eds). Aqacltre sstems research in Arica. Ottawa: International Development

Research Centre.

Mikolasek O, Lazard J, Alhassane M, Parrel P, AliI. 997. Biotechnical management o

small-scale tilapia prodction nits in foating cages in Niger River (Niger). In: Fitzsimmons

K (ed). Tilapia aqacltre: Proceedings rom the Forth International Smposim on

Tilapia in Aqacltre. Ithaca, uSA: Northeast Regional Agricltral Engineering Service.

pp 348-356.

yi y, Kwei Lin C, Diana J. 996. Infence o Nile tilapia (Oreochromis niloticus) stocking

densit in cages on their growth and ield in cages and in ponds containing the cages.

Aqacltre 46:05-5.

ACknoWledgements

Consltative Grop on International Agricltral Research Challenge Programon Water and Food, Project CP34: Improved Fisheries Prodctivit andManagement in Tropical Reservoirs

WorldFish gratell acknowledges the highl valed nrestricted ndingspport rom the Consltative Grop on International Agricltral Research(CGIAR), specicall the ollowing members: Astralia, Canada, Egpt, German,India, Israel, Japan, New Zealand, Norwa, the Philippines, Repblic o Soth

Arica, Sweden, Switzerland, the united Kingdom, the united States o Americaand the World Bank.

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2009

For further information on publications please contact:

Business Development and Communications Division

The WorldFish Center

PO Box 500 GPO, 10670 Penang, Malaysia

Tel : (+60-4) 626 1606

Fax : (+60-4) 626 5530Email : worldfshcenter@cgiar.org

This publication is also available rom: www.worldfshcenter.org

This document is part o a series o 5 technical

manuals produced by the Challenge Program

Project CP34 Improved fsheries productivity

and management in tropical reservoirs.

The other Technical Manuals are:

Cage Culture in Reservoirs in India.

Enhancing fshery productivity in small

reservoir in India.

Building fsh enclosure in Lake Nasser.

Engaging local communities in aquatic

resources research.