J.B. AMON KOTHIAS D. PAULY

R.S.V. PULLlN J. LAZARD M. LEGENDRE

International Center for Living Aquatic Resources Management

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J.B. AMON KOTHIAS D. PAULY

Translations by C. LHOMME-BINUDIN

Republlque de Cote d'lvoire

era

Centre de recherches oceanoloqlques

L'lnstitut francais de recherche scientifique Centre de cooperationinternali o naleen recherche pour le developpernent en cooperation Withthe cooperationof agro nomlquepourle developpement

Cooperation

fran~alse

"A

Centretechn ique de cooperationagrlcole et rurale

THE THIRD INTERNATIONAL SYMPOSIUM ON TILAPIA IN AQUACULTURE

International Center for Living Aquatic Resources Management

L' Inst itutIrancais de recherchesc ien ti fi q u e pour le developpernent en cooperation

Edited by

R.S.V. PULLIN

J. LAZARD M.LEGENDRE J.B. AJ.\10N KOTHIAS D. PAULY

Transl ation s by

C. LHOMME-BINUDIN

1996

Republique de Cote d'lvoire

era

Centre de recherches oceanologiques

Centre de cooperation internationale en recherche agronomique pour le developpernent

With the coo pe ra tio n of

Cooperation tranealse

Centre technique

~A

de cooperation agricole et rurale

Edited by

R.S.V. PULLIN, J. LAZARD, M. LW~NDR~, J.B. AI'ION KOTHIA5 and D. PAULY Translations by

C. LHOMM~-BINUDIN

1996

Published by the International Center for Living Aquatic Resources Management (ICLARM), MCPO Box2631, 0718Makati City, Philippines; and

The Centre de recherches oceanologlques (CRO) - Abidjan, 29, rue des Pecheurs, BP V 18 Abidjan, Cote dIvoire:

The Institut francais de recherche scientifique pour le developpernent en cooperation (ORSTOMj, 213,rue La Fayette, 75480 Paris cedex 10,France; and

The Centre de cooperation internationale en recherche agronomique pour le developpernent/

Departement delevage et de medeclne veterlnalre (CIRAD-EMVT), Campus international de Baillarguet, B.P. 5035,34032Montpellier Cedex 1, France.

Printed in Manila, Philippines.

Pullin, R.S.V., J. Lazard, M. Legendre, J.B. Amon Kothias and D. Pauly. Editors. 1996.

Translated from the French byC. Lhomme-Binudin. The Third International Symposium on Tilapia in Aquaculture. ICLARM Conf. Proc.41, 575 p.

Copyediting: Lilybeth Eleccion, Leticia B. Dlzon, Marie Sol M. Sadorra and Marciana E. Araneta Proofreading: Lilybeth Eleccion, Marie Sol M. Sadorra, Jessica A. Moya, Marciana E. Araneta

and Rachel Africa Layout: Ariel C. Aquisap

Cover: Tilapia design from an Ivorian batik. Cover design by Alan Siegfrid Esquillon.

ISSN 0115-4435 ISBN 971-8709-42-8

ICLARM Contribution No. 1325

Contents

Foreword •...•...•...••••••.•••••••..••••••••••.••.••...•••... viii Preface .•••...••••...••.•.•••..•...•••••••..••.••••••...•••...••.••••.••.•••..••...••. ix

A. KEYNOTE PAPERS

World Tilapia Culture and Its Future Prospects' R.S. V. Pullln 1 Tilapia Culture in Francophone SubSaharan Africa: Current Status and

Future Prospects' J. Lazard and J.-Y. Weigel 17 B. PAPERS PRESENTED

Session I: Culture Systems. Management and Production

Comparative Growth of Oreochromis niloticus and Sarotherodon galilaeus in Small Artificial Lakes in Burkina Faso and the Larger Lakes of

Africa' E. Baijot I. Berry, S. Boude, If.If. Ifabore and A. C. Traore 28 The Integration of Extensive Aquaculture (Acadja-enclos) into the Lagoon

Village Environment in Cote d'Ivoire •J.R. Durand and S. Ifem 33 Philippine Tilapia Farming Technologies and Their Relevance to Africa·

R.D. Ouerrero Ill 42

Acadja-enclos Used in CotedIvoire as an Extensive Aquaculture System •

S. Ifem and J.L.B. A vit 46

Liming of Fishponds in Malawi: A Comparative Study of Limed and Unlimed

Ponds' D.M. Jamu and O.V. Msiska 54

Stock Manipulation in Farmed Tilapias in Malaw i • E.If. W.If. Ifaunda 62 Strategies for Stocking Nile Tilapia (Oreochromis niloticus) in Fertilized

Ponds'

c.r.

The Spontaneous Reproduction of Tilapia: an Opportunity or a Handicap for the Development of African Aquaculture? • J. Lazard and

M. Legendre 87

Selective Broodfish Exchange of Oreochromis niloticus in Large Breeding rtapas Suspended in Earthen Ponds • D. C. Little, D.J. Macintosh

and P. Edwards 92

The Effect of Sex Ratio at Stocking on Growth and Recruitment in Nile

Tilapia (Oreochromis niloticus) Ponds' O. C. Mair and A.A. Van Dam .... 100 Comparison of the Growth of Oreochrornis karongae and O. shiranus

in Fishponds in Malawi· A.O. Maluwaand M.W. Dickson 108 Growth, Survival and Sex Ratios of Oreochromis urolepis hornorurn,

O. niloticus and Their Hybrid Treated with 17a-Methyltestosterone •

D.E. rteyer and R. O. Smitherrnan I 12

Designing New Fish Farming Models Adapted to Rural Cote d'Ivoire •

P. mortssens. M.

oswata. r.

and O. karongae, New Candidate Species for Aquaculture in Open Waters and Fishponds in Malawi· O. V. Msiska and B.A.

Costa-Pierce 129

Management of Tilapia (Oreochromis shiranus and Tilapia rendetth in Ponds of Smallholder Farmers in Mwanza and Zomba West

Districts of Malaw i • J. T.B. Mutambo and S.A. Langston 135 Utilization of On-farm Resources for Aquaculture in Rural Africa' R.P. Noble 141

Hi

nllotlcusin Manured Earthen Ponds' J.P. Szyper and If.D. ttopkins 152 Production of Florida Red Tilapia (Oreochromls sp.) Fry in Brackishwater

Tanks under Different Feeding Regimes and Stocking Densities •

W.O. Watanabe, S.J. Smith, W.D. tieedand If. W. Mueller 160 Production of Florida Red Tilapia (Oreochromis sp.) in Flowthrough

Seawater Pools at Three Stocking Densities • W. O. Watanabe,

J.R. Chan, S.J. Smith, R.J. Wick/undand B.L. Olla 168 Session 11. Nutrition

Use of Terrestrial Plants in Aquaculture in Malawi·1".J. If. Chikafumbwa 175 Waste Vegetable Leaves as Feeds for Juvenile oreochromisshiranus

and TiJapia rendalJi in Mono- and Polyculture • S.If. Chimatiro

and B.A. Costa-Pierce 183

Effects of Varying Protein-energy Levels on Food Consumption, Growth and Body Composition of Sarotherodonmetanotheron(Ruppel.

1852) • A.

ctsse

Feeding Cottonseed Cake to Tilapia (Oreochromis niloticus) in Earthen Ponds with Catfish (C/arias gariepinus) as Police-Fish'

A.J. Middendorp 198

Measurement of the Apparent Digestibility Coefficients for Oreochromis nilotlcusof Agro-industrial By-products Available in Cote d'lvoire •

Y. Moreau 204

Models for Estimating the Food Consumption of Tilapias • M.L.

retomares

and D. Pau/y 21 1

Session Ill. Reproduction and Genetics

Studies on the Effect of Manipulating Hapa Size on Broodstock Conditioning of Oreochromis nitoticus in Fertilized Earthen Ponds' A.J.D. Ambeli

and D.C. Little 223

Significant Proportions of Unexpected Males in Progenies from Single Pair Matings with Sibling Sex Reversed Males of Oreochrornis niloticus •

J.I". Baroiller 229

Comparative Effects of a Natural Androgen, 11.6-Hydroxyandrostenedione, and a Synthetic Androgen, 17a-Methyltestosterone, on the Sex

Ratios of Oreochromis nlloticus • J.I". Beroiller and A. Toguyeni 238 Effects of High Rearing Temperatures on the Sex Ratio of Progeny from

Sex Reversed Males of Oreocbromis nlloticus • J.I". Beroitier.

A. Fostier, C. Cauty, X. Rognonand B. Ja/abert 246 Cold Tolerance in Maternal Mouthbrooding Tilapias: Heritability Estimates

and Correlated Growth Responses at Suboptimal Temperatures •

L.L. Behrends, J.B. Ifings/yand M.J. Bulls 257

Mitochondrial DNA Restriction Endonuclease and Isozyme Analyses of Three Strains of Oreochrornis niloticus • J.B. Ceplt! and D.O.I". Skibinskl ... 266 Triploidy Induced by Heat Shock in Oreochromis niloticus • S.L. Chang

and t,C. Liao 273

Effects of Substrate and Water Quality on Seasonal Fry Production by

TiIapia rendelliin Tanks • B.A. Costa-Pierce 280 A Practical Quantitative Method to Estimate Relative Reproductive Activity

in oreochromisniloticus» A.E. Eknnth, J.B. Capili. J.c. Danting, M.S. Pa/ada-De Vera, E.E. Dionisio, tt.L. Boliver, R.A. Reyes

and M.M. Tayamen 290

iv

Searching for Behavioral Isolating Mechanisms in Tilapias • U. ratter 299 Plasticity in the Parental Cycle of Oreochromis niloticus • J. Y. Oeutier.

M.A. Richerd-Yris, /3. Le raucheux and 11. Foreste 308 Sex Reversal of Tilapia Fry by Immersion in Water Containing Estrogens •

Ci.L Oil/ing, D.O.r. Skibinski and J.A. /3eardmore 314 Effects of Triploidy on Sexual Maturation and Reproduction in Nile Tilapla.

Oreochromis niloticus L. •1'1.0. ttussein, D.J. Penman and

/3.J. McAndrew 320

Aspects of the Reproductive Strategy ofSarotherodon melanotheron:

Comparison between a Natural Population (Ebrie Lagoon, Cote d'lvoire) and Different Cultured Populations • M. Legendre

and J.M. Ecoutin 326

Mouthbrooding Efficiency and Spawning Frequency ofSarotherodon melanotheron (RiippeL 1852) in Culture Environments (Ebrte

Lagoon, Cote dIvoire) • M. Legendre and L. Trebaol 339 A Search for Sex-specific DNA Regions in Oreochromis niloticus •

S.K.J. McConnen D.O.r. Skibinskiand J.A. /3eardmore 349 Comparative Growth of Hybrids (F_I, F₂ and F₃) of Oreochromis niloticus^(L.)

and O. macrochir (Blgr.) • J.-c. Niche. R. Cuvelier. Ch. Tilquln,

/3. Nureille, M. /3ourgois and U. ralter 354

Comparison of Growth Performance and Electrophoretic Characteristics of Three Strains of Oreochromis niloticus Present in Cote d'lvoire •

P. rtorlssens. X. Rognon and I. Dernbele 36I

Genetic Differentiation in Several Stocks ofSarotherodon melanotheron and Tilapia guineensis from Cote dIvolre. Senegal and Gambia·

L. Pouyaud and .L]". Aqnese 368

Growth and Gonadal Development of Triploid Tilapia (Oreochromis

niloticus) • 8. Puckheber and O. tiorstqen-Schwerk 377 Implications of Reproductive Behavior of Captive Oreochromis Broodstock

on the Quality of Their Fry· K.J. Rana 383

Observations on Intergeneric Hybrids in Tilapias •K.J. Rana, /3.J. Nc/urdrew,

O. Wohlfarth and I. Macgowan 391

Study of Genetic Variation in Farmed Populations of Some Species of the

Genus Oreochromis· X. Rognon and R. Ouyomard 398 Basis of the Sexual and Territorial Behavior in Males ofOreochromis

niloticus and Oreochromis mossambicus· Y. Rouger 407 Truss Morphometric Characterization of Eight Strains of Nile Tilapia

(Oreochromis niioticusi . R.R. Velasco, M.J.R. Pente, J.M. Macaranas,

C. C. Janagap and A. E. Eknath 4 15

Estimation of Additive and Nonadditive Genetic Parameters in the Growth

of Fry of Three Strains ofOreochromis spp .• C.V. Yepi-Oneore 426 Session IV. Biology and Ecology

A New Method for Comparing the Growth Performance of Fishes. Applied to

Wild and Farmed Tilapias • D. Peuly, J. Moreau and F. Oayanilo, Jr. .. ... 433 Survival of Tilapia guineensis under Conditions of Low Dissolved Oxygen

and Low ptt •K. Wokoma and I.E. Marioghae 442

Session V. Physiology

The Role of Prolactin in the Adaption of Tilapia to Hypo- and Hyperosmotic

Environments· /3. Auperinand P. Prunet 449

v

aureusto Salinity' M. A vellaand T. Doudet 461 Session VI. Economics and Socioeconomics

Economics of Tilapia Aquaculture in Small Waterbodies in Bangladesh,

M. Ahrned, M.F. Bimbaoand M. V. Oupta 471

Regional Trends in Tilapia Production and Prices in the Philippines'

M.A.F. Bimbaoand M. Ahmed 476

Tilapia Culture in the Senegal River Basin and the Causes of Its Failure·

F.S. Dioufand J.J. Albaret 488

Nile Tilapia (Oreochromis niloticus) Culture in Small Waterbodies under Different Feeding and Fertilization Regimes' M. V. Oupte,

Md. Akhteruzzaman A.If.M. /fohinoorand M.S. Shah 500 Rural Development of Tilapia Culture in Africa: from Myth to Reality'

C. /foffi, M. Oswaldand J. Lazard 505

Which Research for Which Development of Tilapia Aquaculture in

SubSaharan Africa? • J. Lazard 515

Peri-urban Aquaculture in Midwestern Cote dlvoire • M. Osweld,

Y. Copinand D. Montferrer 525

C.POSTEKS

Growth and Food Conversion of Five Strains of Nile Tilapia(Oreoehromis niloticus)

Fry' B.o. Acosta, E.E. Dionisioand A.E. Eknath 537

Historical and Technical Aspects of the Introduction of Tilapia Culture in Colombia'

L.F. Castillo Campo 538

Studies on the Growth Performance and Gonadal Development of Triploid Tilapia

Oreoehromis aureus • S.L. Chang, e.F. Changand I.e. Lleo 539 The Malaw i Central and Northern Regions Fish Farming Project: Research, Progress

and Prospects' M. Diekson 540

Interactions Between Nile Tilapia(Oreoehromis niloticus) and the Pond Community

at Various Fish Densities' F.A.R. Elhigziand P. Larrson 541 Studies on the Control of Tilapia Recruitment Using Tilapia-Predator Polyculture

System in Southwest Nigeria' o.A. Fagbenroand A.A. Salami 542 Observations on the Possible Effects of Salinity, Pond Regime Practices and Behavior

on the Culture of Tilapia guineensisand Sarotherodon melanotheron •

G.D. Igonifagha, S.N. Deekaeand I.E. Marioghae 543

Periphyton Composition and Physicochemistry in an Artificial Habitat (Acadja-enclos) forSarotherodon melanotheroJr-Adiapote Area, Ebrie Lagoon, Cote d'lvoire •

A.A. Konan 544

Production of Pseudo-females ofOreoehromis aureusUsing Ethynyloestradiol •

CH. Melard 545

Consumption of Phytoplankton by Oreoehromis niloticusin Lake Muhazi (Rwanda) •

f.C. Micha, j.P. Deseyand F. Laviolette 546

Documentation and Evaluation ofOreoehromis niloticusPopulations in Ghana for

Aquaculture •j.K. Oforiandj.N. Padi 547

Induced Spawning in Oreoehromis nilotieusL. • E.E. Rodertck, L.P. Santiago, M.-A.

Gareiaand G.

e.

Acute Toxicity of Potassium Permanganate, Petroleum Product and Textile Effluent

to Oreoehromis niloticus :A.A. Salamiand0.0. Oguyemi 549 Analysis of the Morphometries of Three Tilapias(Tilapia zillii, Sarotherodon galilaeus

and Oreoehromis nilotieus)and Their Intergeneric Hybrids' E. Sehwanekand

K. Rana 550

vi

Production of Tilapla and Garden Crops Behaving as Environment Purifier·

K. Sou/eymane, M. Did/erand J. QuJlleret 551

The Development of a Tilapia Strain Registry as Part of FishBase • ltY. Villwock,

U. Sienknecht, R.Froeseand L.Agustin 553

Effects of Dietary Levels of Carbohydrate. Lipid. Phosphorus and Zinc on the Growth and Feed Conversion of Nile Tilapia(Oreochromis ni/oticus) • L. Zhongzie,

L. Wuand Y. Yunxia 554

D. SPONSORS AND COLLABORATORS

Agence de cooperation culturelle et technique (ACCT) 555 Centre de cooperation internationale en recherche agronomique pour le

developpernent (CIRAD) 556

Centre de recherches ocenologtques (CRO) 557

Technical Center for Agricultural and Rural Cooperation (CTA) 558 International Center for Living Aquatic Resources Management (ICLARM) 558 Institut national de la recherche agronomique (INRA) 559

The French Ministry of Cooperation 560

L'lnstitut francais de Recherche Scientifique pour le Developpement en

Cooperation (ORSTOM) 561

Author Index ...•...•.•••...• 563

List of Participants 565

vii

foreword

Interest in the culture of tilapia unites farmers and researchers on nearly all continents in a way more reminiscent of a major agricultural commodity than a fish. Despite having been cultured for over 2,000 years, the majority of research on tilapias has been in the field of ichthyology of natural populations with some emphasis on raising tilapia in aquaria. Since the 1980s, however, the world has seen a major upswing in the culture of tilapia, chiefly Nile tilapia (Oreochromis niloticus)and in related research, especially on tilapia biology, including genetics.

This volume of symposium proceedings shows a strong interest in production systems research and a dawning interest in socioeconomic research. Both of these fields of research are expected to receive much greater attention in the future as the economic and market importance of tilapia increases and as we seek to understand better the distribution of benefits of the different production technologies.

Tilapias, because of the low cost and relative ease of their production, are a potential food fish staple for many people in tropical countries and a globally traded commodity.

Tilapias are used as live feed in the culture of some high-value predatory fish and are also marketed as value-added products (fillets, sashimi) in international trade. This diversity in potential end uses means that future research will have to address a wider spectrum of challenges.

With existing achievements and future challenges in tilapia research in mind, ICLARM is pleased to join with the Centre de recherches oceanologiques (CRO), Abidjan, Cote d'Ivoire, the Institut francais de recherche scientifique pour le developpement en cooperation (ORSTOM) and the Centre de cooperation internationale en recherche agronornlque pour le developpernent (ClRAD) in publishing these proceedings ofThe Third International Symposium on Tilapia in Aquaculture.Thanks to the many individuals and organizations whose contributions and support enabled the holding of the symposium and the production of these proceedings; especially, the Mlnlstere francais de la Cooperation, ORSTOM, ClRAD, the Centre technique de cooperation agricole et rurale (CTA) , the Agence de cooperation culturelle et technique (ACa), the Institut national de recherche agronomique (INRA) and the Institut des Savannes (IDESSA).

Dr. Meryl

J.

viii

Preface

The Third International Symposium on Tilapia in Aquaculture (ISTA Ill) was one of the largest aquaculture conferences ever held in Africa. Building upon the work presented at ISTA I (Nazareth. 1983) and ISTA I1 (Bangkok, 1987)and upon the ever-increasing research efforts in support of tilapia farming, the proceedings of ISTA III will, we trust.

be seen as another milestone in the development of tilapia as a globally accepted fish commodity and a contribution to the development of tilapia farming.

Africa, the "home oftilapias," has yet to benefit as much from tilapia farming as have other regions. However, African aquaculture research and development are producing promising results, despite the economic difficulties under which much of these are undertaken.

Among the64papers and 17abstracts of poster papers published here,20were contributed by African participants. We hope that support for the development of aquaculture in Africa-particularly using species like the tllaplas-fish that feed low in the food chain and that can be farmed efficiently and without undue environmental impacts-will be increased and that Africa will become a more significant producer of farmed tilapias both for its own people and for export to the rest of the world.

ISTA III was generously supported by the Agence de cooperation culturelle et technique (ACCT). the Centre de cooperation internationale en recherche agronomique pour le developpernent-Departernent delevage et de rnedecine veterinaire (CIRAD-EMVT), the Technical Center of Agricultural and Rural Cooperation (CTA). the French Ministry of Cooperation, the Institut national de la recherche agronomique (INRA) and the Institut francais de recherche scientifique pour le developpernent en cooperation (ORSTOM).

Information concerning these and others who assisted ISTAIII is given at the end of this volume.

The long period that it has taken to publish these proceedings since ISTA IIIwas held is regretted. Those concerned underestimated the difficulty of the task of compiling thoroughly edited, bilingual proceedings. This entailed very lengthy correspondence with some authors and among the editors, who wished to maintain high standards of scientific publishing and to include, as far as possible, all information presented. Despite the long hiatus, we hope that the value of these proceedings has not been diminished.

We applaud and thank all those who contributed to the success of ISTA III especially the organizing committee: [ean-Francois Baroiller, Adou Cisse , ]ean-Rene Durand, Saurin Hem. Catherine Lhomme-Binudin. Pierre Luquet, Kassoum Traore and Michael Vakily.

We also thank Jean Baptiste Avit, Adou Cisse , Ziriga [osue Oterne , Sylvain Gilles, Rerny Dugue, Jesus Nunez-Rodrlguez and [ean-Francols Agnese for their help with the blueprint.

As we go to press, ISTA IV has been announced. It will be held in Orlando, Florida, on 9-12 November 1997.ISTA IV will doubtless be an opportunity for the world to see the giant steps that tilapia farming has taken since 1STA IIIand we wish its organizers and participants every success as they contribute further to one of the fastest growing sectors of world food production.

The Editors

ix

A. KEYNOTE PAPERS

World Tilapla Culture and Its Future Prospects-

R.S.V. PULLlN

International Center for Living Aquatic Resources Management

MCPO Box 2631,0718 Makati Metro Manila, Philippines

PULLlN, R.S.V. 1996. World tilapia culture and its future prospects, p. 1-16. In R.S.V. Pullin,J. Lazard, M.

Legendre and J.B. Amon Kothias and D. Pauly (eds.) The Third International Symposium on Tilapia in Aquaculture. ICLARM Conf. Proc.41, 575 p.

Abstract

Tilapias are farmed worldwide in tropical and subtropical areas and occasionally elsewhere where warmwaters (thermal effluents or geothermal springs) are available. FAO statistics(1985-88) report tilapia culture in 68 countries. The annual global production of farmed tilapias, actually reported as such, has been static over this period: Z63,OOOtin 1985 and Z64,OOOtin 1988. If, however, estimates of production from Egypt and Vietnam (which are sometimes reported as "freshwater fishes") are included by assuming that this is nearly all tilapias for Egypt and50% tilapias for Vietnam in 1988, then the global total for farmed tilapia production in 1988 was about 380,000t. Over95% of current production is Oreochromis spp. and their hybrids, with 0.nifoticusthe predominant single species. Prospects for expansion oftilapia culture depend upon matching future Research &.. Development (R&..D) efforts to the needs and circumstances of producers (most of whom will be new entrants, not only to tilapia culture but to any form of fish husbandry) and of consumers of domestic and export produce. The constraints to expansion of tilapia culture are, as in warm water aquaculture:

negative attitudes and policies, poor breeds, poor nonsustainable farming systems and possible adverse environmental impacts.

Recent Production Statistics for Tllapla Farming and Their Significance

Table 1 lists the best available statistics for farmed tilapia production from 1985 to 1988. In Africa, there are 29 tilapia farm- ing countries but only seven produce >

100 t-year^1. In Asia, 16 countries farm tilapia and nine produce thousands or tens of thou- sands of tyear^1. Other regions have fewer tilapia farming countries (Caribbean, seven;

Europe, one; Latin America, 10; Mediter- ranean/West Asia, five; Pacific, two; and the USA) and production in these regions rarely exceeds hundreds of tyear' for a single country. Such statistics are difficult to collect from remote areas and there is probably under-reporting. There are also

'/CLARM Contribution No.841.

some inclusions of catches from "enhanced"

or "culture-based" fisheries; for example, nearly all the Cuban production derives from stocked reservoirs. What do such statistics mean? Is tilapia farming doing well? Does this production represent a good return on investment in R&.D? The overall answer would be "probably no," or at least "not yet."

At the close of ISTA 11 (Pullln et al. 1988), tilapia farming seemed to have "come of age" because of the successes of ISTA I (Fishelson and Yaron 1983) and 11: a grow- ing enthusiasm for tilapia farming, a large supportive research effort and indications of progress towards solving long-standing technical problems such as population con- trol. Moreover, tilapia farming is clearly not yet significantly hampered by diseases (there are only five papers on diseases out of a total of 259 in the three ISTAs) or by diffi- culties in persuading the fish to breed and to grow on a wide range of cheap feeds.

Table 1. Production of tilapias from aquaculture (1985-88). Entries in brackets are production data reported to FAO as "freshwater fishes," nottilapiasper se and are included for those countries in which they include some significant tilapia production. All data are taken from the most recent information (FAO 1990), unless referenced otherwise. All remarks have been added by the present author. Blank entries here do not necessarily mean zero production; many reflect the difficulties of obtaining reliable information. This table is modified and updated from Pull in (1991).

Production (t)

Burkina Faso 0. nilotlcus 43 40 36 7

Burundi Various tilapias 2 21 25 24

Cameroon Various tilapias 91 87 96 116

Central African O. niloticus 283 190 85 77

Republic

Congo 0. niloticus 39 82 115 200

COte dIvoire O. niloticus 559 503 648 740

Ethiopia O. niloticus

T. zillii

Gabon Various tilapias (2) (3) (3) (2)

0.niloticus

Ghana 0.niloticus 321 225 270 297

Guinea Various tilapias 2 1 1

Kenya 0.niloticus 113 I 14 121 169

Liberia O. niloticus 8 6 3 2

Madagascar Various tilapias 74 36 38 42

Country Species cultured 1985

AFRICA

Angola Tilapia sparrmanli 2

Benin Various tilapias 11

1986

15

1987

14

1988

17

Remarks

Culture of other species is anticipated.

This probably includes Oreochromis,

Sarotherodonand Tilapiaspp. Exotic species including 0.niloticusand O.spilurushave been recently introduced.

Further development of aquaculture will probably concentrate on this species.

The best prospect for future expansion is 0.

niloticusculture.

As for Cameroon.

As for Cameroon.

There are good prospects for expansion of0.

niloticusculture. There is also research to find suitable species or hybrids for brackishwater lagoon culture.

Much of the country is too high and cold for tilapia culture.

There is scope for expansion of aquaculture using brackish- and freshwater tilapias.

Other cultured species includeS. galilaeus, S.

melanotheronand T.zillii.

Other cultured species include O. spilurusand T.

zillii.

Small quantitites of tilapia, principally O.

niloticus,are grown with common carp.

continued

Production (t)

Country Species cultured 1985 1986 1987 1988 Remarks

Malawi Various tilapias 65 66 83 96 There is successful tilapia culture, principally0.

shiranusand T.rendalli,on sugar estates and in small village ponds.

Mozambique Various tilapias 5 17 20 Probably mainly

a.

native tilapias and possibly 0.niloticusis likely to expand.

Niger

a.

cultured.

Nigeria Various tilapias 4,573 3.274 3,602 3,962 Nigeria has good prospects for expansion of

freshwater aquaculture

(a.

melanotheronand hybrids.

Rwanda

a.

a.

Senegal 0.niloticus 1 2 2 10 Aquaculture is expanding using0.niloticus.

Sierra Leone

a.

Sudan

a.

tllaplas, such as T.zillii.

Tanzania

a.

0.niloticus, is likely to expand.

Togo

a.

T.zillil)and exotics, particularly

a.

a.

Uganda Various tilapias 13 21 27 24 Probably mainly

a.

zaire

a.

probably also significant culture of other tilaplas, such as

a.

Zambia

a.

species, introduced

a.

Zimbabwe Various tilapias 38 42 46 49 Now an expanding tilapia culture industry,

changing from culture of native species. such as

a.

a.

a.

a.

Subtotals for 29 - - - _UJ

countries' 6,598 5,621 6,213 6,848

- - -

- - - -

"Excludes Gabon.

continued

Table 1 (continued)

Production (t)

Country Species cultured 1985 1986 1987 1988 Remarks

- - - ASIA

Bangladesh O.nlloticus

-

probably develop rapidly.

Cambodia O.nlloticus Culture of0.nllotlcusin ricefields and ponds

0.mossambicusis likely to expand.

China 0.niloticus 23,800 29,500 34,800 39,000 Tilapia culture is expanding especially in the warmer southern provinces.

Hong Kong O.niloticus 1,500 1,435 1,700 1,690 Freshwater aquaculture in Hong Kong is

disappearing as land values rise.

India O.mossamblcus TraditIonal attitudes are changing. There is

interest in acquiring good strains of O. niloticus.

Indonesia O.nilotlcus 6.920 8,524 9,831 10,750 TiJapia culture is expanding, including now cage O.mossambicus 35,410 15,487 25,228 25,228 culture of red hybrids.

Japan Various tilapias 4,180 4,113 4,624 4,760 Future expansion is unlikely because of the cold

climate.

Korea (Republic of) O.nilotlcus 118 120 56 92 As for Japan.

Laos O.nlloticus These species are present for aquaculture.

(and 0.mossambicus)

Malaysia Various tilapias 39 241 It has been difficult to separate species and

hybrids in the statistics.

O.mossambicus 313 575 539 2,350 O.niloticusculture is likely to expand.

Myanmar (Burma) O.mossambicus This species is present for aquaculture.

Pakistan O.niloticus 2 There is new interest In tilapia culture In

O.mossambicus 313 Pakistan, particularly in acquiring new stocks of

O.nilotlcus.

Philippines Various tilapias 27,206 30,602 44,682 48,327 There is interest in seawater culture of O.

O.nilotlcus 15,434 25,217 31,087 26,719 mossambicusand hybrids. Culture of O. nilotlcus

is expanding.

continued

Production (t)

Country Species cultured 1985 1986 1987 1988 Remarks

Taiwan Tilapias: mainly 51,820 49,241 51.720 55,561 A large, dynamic tilapia culture industry using

O.niloticusx O.aureus highly intensive systems. The statistics here are

and otherOrechromis from the Taiwan Fisheries Bureau.

hybrids

Thailand O.mossamblcus 1,432 879 476 476 O.niloticusis the prefered species.

0.nlloticus 15,128 18,886 16,920 16,920 Some red hybrids are also cultured.

Vietnam Various tilapias 50,696 49,324 (115,000) (115,000) Tilapia culture (mainly O.nllotlcus, O.

mossambicusand hybrids) is likely to expand.

Subtotals for 14

countries' 234,272 233,903 ZZ 1,702 232,t14

- - - CARIBBEAN

Bahamas Various tilapias 30 30 ZZ 36 Freshwater and seawater systems; red tilapias are

esteemed.

Cuba O.aureus 14,675 14,942 15,270 13,268 Largely reservoir production and probably an

underestimate as O. niloticusis also present in Cuba. Production is expanding.

Dominican ? 3 3 3 3 Tilapia culture is probably now expanding.

Republic

Jamaica O.niloticus 1,046 1,442 1,500 2,400 Production is expanding rapidly.

Puerto Rico Various tilapias 3 Freshwater pond and cage culture are being

O.niloticus 7 encouraged.

US Virgin Islands Various tilapias 6 7 7 2 Probably mainly O. aureus.

Subtotals for 6

countries 15.760 16,424 16,802 15,719

bExcludes Bangladesh, Cambodia, Laos (and Vietnam for 1987 and 1988). continued

V'I

Table 1 (continued)

Production (t)

Country Species cultured 1985 1986 1987 1988 Remarks

LATIN AMERICA

Brazil Various tilapias Progress towards sustainable aquaculture has

been slow.

Colombia 0.nJloticus 300 300 498 800 Production of O.niloticusand red tilapias

T.rendalli 2 2 2 2 is expanding.

Costa Rica Various tilapias 50 50 120 142 Probably mainly O. nlloticus,0.aureusand some

T.rendelll.

El Salvador O.niloticus 15 15 16 15 No recent information available.

Guatemala Various tilapias 70 70 103 103 ProbablyOreochrornisspecies and hybrids.

Guyana O.mossambicus 12 11 13 13

Mexico Various tilapias 1,611 2,270 2,395 2.395 As for Guatemala.

Nicaragua 0. aureus 2 1 18 14

Panama O.nilotlcus 69 126 166 140 0.niloticusculture is most likely to expand

O. eureus 4 7 9 0 in integrated farming systems.

Various tilapias 7

Peru Various tilapias 52 36 89 230 0.niloticusand hybrid tilapia culture may expand

in the forest regions isolated from marine fish supplies.

Subtotals for 9

countries 2,187 2,888 3,429 3.861

MEDITERRAN.EAN/WEST ASIA

Cyprus Various tilapias 2 2 1 1 Limited culture ofOreochromlsspecies and

hybrids; obvious climatic restrictions.

Egypt O.nJloticus (47.346) (50.000) (51,300) (57,100) Egypt cultures O. nlloticus,0 aureusand

O.aureus T.zilliibut statistics are disaggregated.

T.zl/lIi

Greece Various tllapias 16 28 As for Cyprus. Only intensive commercial

systems, with seasonal environmental control.

are possible.

<Lacking data from Brazil. continued

Production (t)

Country Species cultured 1985 1986 1987 1988 Remarks

Israel Various tilapias. 4.114 3.238 4.025 4.536 A dynamic tilapia culture industry and a world

mainly0. niloticus in intensive culture technology. Expansion is

x 0. eureushybrids limited by climatic constraints and aridity

Kuwait Various tilapias A large research effort into saltwater culture of

tilapias showed O. spilurusto be a suitable species for commercial aquaculture.

Saudi Arabia O. niloticus 6 120 300 Saudi Arabia. In common with some other Gulf

0.spilurus 18 28 States. seeks food security through Intensive

domestic production. Tilapia culture is just beginning.

Syria Various tilapias 225 357 357 357 Similar climatic constraints to Israel.

Subtotals for 5

countries' 4.341 3.603 4.537 5.249

- -

OTHER REGIONS

Belgium 0.niloticus 120 160 200 230 Heated water culture (power station effluent).

Fiji 0.niloticus 3 3 1 1 There is a growing interest in O.niloticusculture.

Various tilapias

Guam Various tilapias 66 102 125 125 Mainly O. niloticusand hybrids, including red

tilapias.

Khazakstan 0.niloticus(and 0.niloticusculture in a power station in

other tilapias?) Khazakstan has been reported.

dExcludes Egypt; data lacking for Kuwait. continued

-...I

Table 1 (continued)

Country

USA

Subtotals for 4 countries"

TOTALS

ADJUSTED TOTALS

Prod uction (t)

Species cultured 1985 1986 1987 1988 Remarks

Various tilapias 5 20 There is some culture of Oreochromis species and

hybrids in the warm southern states and in geothermal waters. Climatic constraints and bans on introductions/transfers of exotic species may limit expansion. but some commentators forecast otherwise (Davlin 1991).

- -

194 265 326 376

263.350 262.704 253.009 264.168

- -

- -

310.696' 312.704' 361.809⁸ 378.868⁸

"Lacking data from Khazakstan.

'Includes freshwater fish data from Egypt as if all is tilapia(1985 [47.346t], 1986 [50.000t] and 1988[57.100tll.

81ncludes freshwater fish data from Egypt as if all is tilapia(1987 [51.300tj and 1988 [57.100tJ) and freshwater fish data from Vietnam as if50%is tilapia (1987 [57.500tj and 1988 [57.500tJ).

This enthusiasm may have lessened. The overall rate of increase in tilapia production from 1985 to 1988 was only 7.3%·year-' on the adjusted figures (Table 1).It probably remains slow; for example, production in Taiwan was 47,089 tin 1989 and 53,103 t in 1990 (Fisheries Yearbook, Taiwan Area, 1989-90). Furthermore, there is only one or a few leading countries in each developing region, while the rest produce relatively little. Given the many positive attributes of tilapias as farmed fish (Pullin 1985), what Is holding back tilapia farming in most developing countries?

Constraints

Very few people know how to farm tllaplas well. Moreover, tilapia farming systems are very variable. In the Philippines, the big- gest producer in the world, tilapias are farmed in fresh- and saltwater ponds, as mixed- sex or monosex male stocks, in mono- or polyculture and also in cages, ricefields, tanks, etc. Progressive farmers are always trying to find ways to improve these sys- tems. Potentialnew entrantsto tilapia farming remain ignorant of how to do it and per- ceive it as a risky enterprise. The solution everywhere is to develop sustainable and environmentally acceptable tilapia farming systems in which new entrants can have confidence. Tilapia farming as apart-time enterprise in integrated farming systems has a great appeal because it can help to spread risks (Edwards et al. 1991).

Inappropriate Supportive Research Pullin and Maclean (1992) reviewed over 2,400 research publications on tilapias, mostly comprising research in a single dis- cipline: 94% biotechnical and 1.4% social science (mainly economics). Only 5% were considered interdisciplinary. Thus, there are

9 large interdisciplinary and social science research gaps in the technical support base for tilapia farming. Moreover, researchers themselves usually conceptualize problems and needs without consultation with far- mers.

Antl-tlJapla Attitudes

Where tilapias are native fish, they are almost always regarded as an excellent human food and a valued natural resource.

AntHilapia attitudes are restricted to ar- eas in which tilapias have been or could be introduced as exotic species for aquaculture or enhanced fisheries. This has not been well-documented in the primary scientific literature. Information from Latin America, the Pacific or South Asia (the main regions where anti-tilapia attitudes are preva- lent) is largely in reports or in semi-tech- nical and popular serials. Uwate et at. (1984) have reviewed the situation for Pacific Is- land nations, most of which dislike tilapias, Fiji being a major exception. Nelson and Eldredge ( 1991 ) have reviewed the effects of tilapia introductions in the South Pacific and Micronesia.

The basis for antHilapia attitudes is two- fold: (1) a preference for and an impression of the "superiority" of nontilapiine native species that are traditional foods and (2) bad experiences with tilapia introductions or news of this from elsewhere.

Preference for farming native species is not only understandable, it is sensible. Clearly, aquaculture development in Africa should use tllaplas, catfishes and other species, including native carps, rather than follow- ing external or local advice to use exotic species. Such an approach, aiming at a valorization of autochtonous species for aquaculture, has been particularly devel- oped in Cote d'Ivolre since the mid-1970s with good results and prospects (Hem et al., 1994). Another example is MalaWi, which is now endeavoring to eradicate the "mistake"

of inappropriate introduction by destroying

common carp tCyprinus carpio) stocks in the southem region, lest it become transferred to the Lake Malawi catchment and establish itself there with unpredictable ecological consequences. Africa has a great wealth of native species to be screened for aquaculture use, not just the tilapias.

In Asia, Latin America and the Pacific, however, the position is more complex. The history of tilapia introductions started there, as in all developing regions, with narrow genetic stocks ofOreochromis mossembkus, mostly derived from a tiny feral popula- tion. These introductions gave poor stocks for aquaculture. Moreover, escapees some- times became widely established in inland and coastal waters, outcompeting highly regarded native species and interfering with aquaculture and fisheries operations (e.g., Phillippart and Ruwet 1982; Gillett 1989).

There are no comparable reports of ad- verse ecological consequences of introduc- tions of0.niloticus,which has become the basis for most of the world's tropical fresh- water tilapia culture. In many countries, however, 0. mossambicus has given all tilapias a bad reputation. It is a highly op- portunistic, euryhaline and eurythermal species. Paradoxically, it is not necessarily a bad species for all purposes; for exam- ple, it provides valuable fisheries in Sri Lankan reservoirs (De Silva et al. 1988; Amarasinghe and De Silva 1992). Its Africannativestocks have never been thoroughly screened for aquaculture potential. Moreover, it provides an important food source for some very poor coastal dwellers (Costa-Pierce 1988).

Attitudes to further development of tilapia culture in which tilapias are exotic as fol- lows:

PERSISTENTLY ANTI-T1LAPIA AND LIKELY TO REMAIN SO.

Countries that seek expansion of aquaculture but that have never imported tilapias and fear the ecological consequences,

prefer native species, or both-e.g., Ne- pal.

Countries that attempted to develop aquaculture (mainly using0.mossambicus) and which experienced failures, ecological disruption, non-acceptance of tilapias or combinations of these-e.g., Kiribati.

Countries into which tilapias were unofficially or accidentally introduced and escapees became pests-e.g., Australia.

FORMERLY ANTI-TILAPIA BUT NOW CHANGING OR LIKELY TO CHANGE.

Countries that farm native species and fear disruption by tilapia introductions, but still need good species for low-input, rapid- cycle, small-scale systems or for larger-scale intensive systems-e.g., Bangladesh, India and Pakistan.

Countries with little aquaculture, with potential for tilapia farming and with fears of ecological disruption diminishing after good experiences with 0.nlloticusand salt- tolerant hybrids-e.g., Puerto Rico and other Caribbean nations.

BECOMING LESS FAVORABLE?

Countries that formerly introduced tilapias for aquaculture but in which aquaculture technology for preferred nativespecies is now being developed and/or fears about the ecological disruption persist-e.g., much of South America.

STILL EVOLVING

Countries in which aquaculture is newly evolving and the relative importance of carps, tilapias, catfishes and other species is not yet determined-e.g., Cambodia, Laos and Vietnam.

Countries in which cl imatic factors (cold seasons, aridity or both) limit tilapia culture unless cost-effective solutions are found-e.g., China (parts of), Europe, Japan,

Korean peninsula, Mediterranean, West Asia and USA (mainland).

KEEN TO EXPAND TILAPIA CULTURE.

Countries in which tilapias are popular as farmed fish and there is scope for in- creased production for domestic consump- tion, export or both-e.g., southern China, Fiji, Indonesia, Malaysia, the Philippines and Thailand.

With respect to tilapia transfers, past mistakes should not be repeated. Interna- tional Codes of Practice for transfers of exotic species should be followed. However, some of the private sector and some high offi- cials will probably continue to make trans- fers without adequate appraisals. Two ex- amples from the past, recounted by Gillett (1989) illustrate this attitude and the pos- sible consequences-usually a permanent legacy:

In Westem Samoa, the following advice was given to the government to start tilapia (0. mossambicus) culture:

"It is evident that it would be preferable to investigate all fac- tors for a whole year, but this would involve great expense and even then, there might be some uncertainty with a few points.

It is much cheaper to start with an experimental pond and stock it with tilapia (Van Pel 1954)."

The view of the Minister for Natural Resources Development in Kiribati, as reported by (uta (1989), was:

"The well-known tilapia fish was introduced in our fish ponds and landlocked lagoons by well- meaning developers to increase protein supply. The result was that this highly competitive fish, which rarely grows larger than six inches in Kiribati, has replaced

1 1 the culturally, commercially and nutritionally important milkfish .... Ifonly applied research on the ecology of tilapia ... had been conducted beforethe project."

Persistent Technical Problems

POPULATION CONTROL

Population control in farmed tllaplas has been reviewed by Baroiller and jaJabert ( 1989) and Mair and Little (1991). They mention a wide range of methods: sex reversal by androgenic hormones, intermittent harvest- ing, manual sexing, predators, high density stocking, cage culture, delayed sexual maturity, sterilization, hybridization and the

"YY" broodstock route for 0. niloticus.Out of all these options, very few have progressed from use in experimental studies or development trials to widespread adoption by farmers. The exceptions are combinations of hormonal sex reversal and hybridization (widely used in Israel and Taiwan) 'and hormonal sex reversal of0.niloticus, which is becoming more widespread in Asia.

Elsewhere, research proposals and de- velopment project plans still select ap- proaches to tilapia population control more or less on guesswork and hardly ever with a thorough assessment of user (farmer and consumer) perspectives.

POOR BREWS

Tilapia farming, like all warmwater aquaculture, has been very slow in recog- nizing the scope for improvement of farmed breeds by applied genetics. As reviewed by Pullin and Capili (1988), most farmed tilapias derive from very small founder stocks and little has been done in most countries (exceptions are Israel and Taiwan) to im- prove farmed breeds, other than occasional attempts at hybridization. Until recently, there were no attempts to apply additive selective breeding to farmed tilapias: an

approach that has been well-proven in live- stock but so far only with salmonids in aquaculture (Gjedrem 1985).

Immense opportunities have been lost.

For example, a founder stock of0.niloticus

collected from the wild in Egypt in 1962 was transferred to Japan and Its descend- ants used for transfers to Thailand in 1965 (and from thence to the Philippines in 1972).

This "strain" is still used by tilapia farmers:

known as "Chltralada" strain (Thailand) and 'Thailand" strain (Philippines). After 26 years (certainly more than 50 generations) un- der "domestication," the performance of the"Thailand"strain in the Philippines, across a range of environments, is inferior or similar to that of a new founder stock of wild Egyptian fish collected in 1988 (Pull in et al. 1991;

Eknath et al. 1993).

This neglect of the importance of applied genetics in tilapia breeding and ignorance among farmers about the genetic conse- quences of stock management means that most farmed tllaplas are close to wildtypes

or worsein their culture performance. So- lutions to the problem lie in wise stock management (Eknath 1991), the evolution of national breeding programs (Eknath et al. 1991) and the real ization by research- ers that the best route to sustainable ge- netic gain is to marry the "one-step" ge- netic management techniques to which they are attracted as short-cuts to improvement (e.g., hybridization, polyploidy and possi- bly transgenic fish) with long-term addi- tive selective breeding.

POOR fARMING SYSTEMS

It is impossible to disaggregate tilapia production statistics into cage, ponds, ricefields, tanks and other farming systems.

Indeed, ICLARM proposed the "aquatic chicken" label for tilapias because they can be farmed profitably in a wide range of systems from simple backyard systems to highly intensive "factory farms"-as can poultry.

The success of any tilapia farming sys- tem depends upon its sustainability and environmental compatibility, which in turn depend upon cost-effective and wise use of resources (land, water, capital and other inputs) and coexistence with other enterprises and environmental care. At present, most new tilapia farms are experiments. This will persist until tllapla farming systems become better known: more like the routines used for poultry.

The key to a more reliable farming sys- tem may be simple. For example, the adop- tion of hapa nursing techniq ues has allowed farmers in northeast Thailand to become more confident and successful new entrants to aquaculture on their small-scale rice-based farms (Little et al. 1991). Nursing the fry of tilapia and other fish in a hapa allows the farmer to see them everyday, to watch them grow on whatever feed resources are at nand and ultimately to release larger, more "predator-proof' fingerlings into small ponds and ricefields.

One major unresolved issue in tllapla farming is to what extent hatchery/nurs- ery operations and growout will be under separate management. They are separated in most of aquaculture, and tend to be so in the most advanced tilapia farming ar- eas, such as Israel and Taiwan. Elsewhere there is usually a mixture of public and private sector seed supply to growers, with some growers raising their own seed.

Pullin and Maclean (1992) recommended research "on the dynamics of aquaculture enterprises and of their interactions with other enterprises (agriculture, fisheries, forestry, recreation and waste management).

Resource flows and trade-offs in terms of common 'currencies' (land, water, nutrients, energy and cash itself) must be quantified so that the options for balancing and inte- grating aquaculture development can be evaluated within farms, communities and wider coastal and watershed areas."

Within this general framework, it is clear that the broad categories of tilapia farm-

ing systems have some general problems (Table 2). Solutions will come from closer collaboration between farmers and research- ers, Moreover, because of the possibility of genotype x environment interactions, research towards better systems and bet- ter breeds must be interactive.

The Future

The comments on inappropriate research above apply not only to small-scale aquaculture in developing countries, but also to large-scale corporate aquaculture.

Davlin (t99t )forecasts the entry of a grow- ing number of large corporations in aquaculture and believes this will guaran- tee the success of future intensive systems, He states:

"Aquaculture as an industry has been led by academia/marine biologists for 30 years. It was their technological breakthroughs that enabled the small farmer to look upon aquaculture as an additional source of income.

Eventually, the farmer saw it as a way of life and academia and fish farmers made an early 'odd couple'."

His "odd couple" scenario is still a fair description of many current relationships between academic tilapia research and tilapia farmers. Many companies just get on with the job themselves and learn by their own mistakes.

Researchers generally ignore the fact that technology for food production, whether generated through private- or public-funded research, is not neutral. It will favor either large-scale corporate farming concerns or small-scale farmers-very rarely both.

It is probably cheaper, more profitable and more environmentally acceptable to farm tropical fish in lessintensive systems

13 in developing countries; for example, value- added white fish products, like tilapia fil- lets (pullin 1984). Davlin (1991) mentions new commercial agreements between Co- lombia and the USA to package and han- dle tilapia produced in Colombia and that Solar Aquafarms, Inc., California (using in- tensive recycling technology) will produce over 2,000 t of tilapia in 1992. Will there still be room for small-scale farmers to pro- duce fish for domestic markets and export?

Davlln's (1991) punch line and last word is:

"Tilapia will, during this decade, join catfish as the dominant modest-priced fish in the US, in our view.

The future for tilapia farming remains bright, despite the somewhat disappointing recent statistics. In Africa, wherever inland aquaculture flourishes, tilapias are likely to be a major, if not the major farmed fish commodity. In Asia, there is likely to be significant expansion of tilapia farming in China and Indochina (Cambodia, Laos and Vietnam) and probably also in some of the major producing countries (Philippines and Thailand). In Latin America and the Carib- bean, the situation is less clear. Tilapia pro- duction may expand in countries where it is already a proven success (e.g., Cuba and Jamaica) but native species may be increas- ingly preferred for aquaculture in much of these regions. In the Mediterranean/West Asia, climatic constraints and resource limi- tations will probably prevent much expansion of tilapia farming. This also applies to Eu- rope and northeast Asia. Tilapia farming in the Pacific is unlikely to excite much inter- est, except in Fiji. In the USA, if the market for tilapia develops as forecast by Davlin (1991), there will undoubtedly be more attempts to supply this from US-based farms as well as from imports.

Pullin (1991) forecasts a doubling of world tilapia production over the next

to

Table 2. Problems associated with tilapia farming systems.

System

Cages

Pens. acadja-enclos, etc.

Ponds

Tanks. raceways and other intensive systems. including recycling

Hatchery/nursery systems

Major problems

Ad hoc design. guessed at or copied from elsewhere; poor feed conversion; fouling;

short operational life.

Still experimental.

Nutrient starvation; ad hoc stock management;

water availability /quality.

Largely experimental or guesswork at site- specific designs.

Low and/or seasonal output of fry/fingerlings;

no consideration of genetic consequences of brood stock management; low adoption of monosex seed technology.

Farmers' needs

Systems specifically designed for tilapias in fresh-. brackish- and saltwater.

Reliable. sustainable systems that match their resources.

Sustainable systems. well-integrated with other enterprises.

Reliable guidelines-as exist for trout culture.

Reliable seed supply systems that maintain genetic quality and 100% male seed production. where such is appropriate.