the gher revolutionaquaticcommons.org/205/1/aquacultureasia_8_4_2003.pdf · effective...

ISSN 0859-600X Volume VIII NO.4 October-December 2003

The "Gher Revolution"

Immunostimulants in larviculture

Tilapia seed production in Ho Chi Minh City

Tackling aquatic animal disease

Now available on CD-ROM

Rice-Fish culture in China

Seaweed mariculture in India

Freshwater prawn M. nobilii

Aquaculture Asia is an autonomous publicationthat gives people in developing

countries a voice. The views andopinions expressed herein arethose of the contributors and do

not represent the policies orposition of NACA

EditorSimon Wilkinson

[email protected]

Editorial Advisory BoardC. Kwei Lin

Donald J. MacIntoshMichael B. New, OBE

Patrick Sorgeloos

Editorial ConsultantPedro Bueno

NACAAn intergovernmental

organization that promotes ruraldevelopment through

sustainable aquaculture. NACAseeks to improve rural income,increase food production and

foreign exchange earnings andto diversify farm production. Theultimate beneficiaries of NACAactivities are farmers and rural

communities.

ContactThe Editor, Aquaculture Asia

PO Box 1040Kasetsart Post Office

Bangkok 10903, ThailandTel +66-2 561 1728Fax +66-2 561 1727

Email [email protected] http://www.enaca.org

Printed by Scandmedia

1

From the Editor’s desk

Shrimp anti-dumping dispute escalates

Volume VIII No. 4 ISSN 0859-600XOctober-December 2003

Another aquaculture trade dispute is looming and this time the target is shrimp. A USindustry group largely representing US shrimp fishing interests - the “SouthernShrimp Alliance” - has filed a complaint alleging six countries of dumping shrimp onthe US market - namely Brazil, China, Ecuador, India, Thailand, and Vietnam.

The Southern Shrimp Alliance claims that the domestic price of shrimp has fallensignificantly in response to the ‘dumping’ of ‘unfairly priced’ imported product on theUS market. Their petition proposes the introduction of tariffs ranging from 30-267%against the countries named above. Exporting countries prefer to use the term‘competetively priced’ and point to the substantially lower production costs in Asiaand South America. The ITC will release a preliminary decision on 17 February.

One significant difference between the looming shrimp dispute as compared to therecent action against Vietnamese catfish is that this time US producers face strongopposition to their position at home. Much of the US seafood processing industry isreliant on imported shrimp product as domestic production is not sufficient to meetdemand. Many processors and retailers are opposed to the introduction of tariffs thatare likely to hurt their businesses.

We expect that the blow will fall hardest on the many people in Asia and elsewherewhose livelihoods depend on shrimp aquaculture, should the case ultimately besuccessful. In response to this challenge, there is a need for enhanced informationexchange, and coordinated and effective actions. Several NACA members have takenlegal assistance, and a vigourous defence of the charges is expected. In response,NACA will enhance its shrimp media monitoring program, aiming to bring regularnews of the anti-dumping case, from within Asia, and the US, to NACA members. Wehope this will prove useful to members in monitoring developments and taking actionon this important challenge. The service is available free by subscribing to thenewsletter through the NACA web site. NACA will continue to respond to memberrequests for further information on the antidumping case, and to encourage andsupport as far as possible sharing of experiences and coordinated action among ourmembers to address this major challenge to our aquaculture industry in Asia.

On a more postitive note, the new NACA website has been launched. This time its‘more than just a website’ - we are moving towards the establishment of an ‘onlinecommunity’ for the network. The people in participating NACA centres are widelyseperated by the tyranny of distance, so we have endeavored to provide a ‘virtualplace’ where they can ‘meet’ to discuss issues, share information and collaborateonline. To this end we have made the website interactive - you can submit your ownlocal news, events and stories online to share with your colleagues all over Asia. Wewill also shortly activate some discussion forums where you can post questions andtalk to your colleagues from throughout the network. Please register as a member ofthe site to create your own personal website account.. It is of course, completely free.

The NACA website may be found at http://www.enaca.org.

aquaculture Asiaaquaculture Asiaaquaculture Asiaaquaculture Asiaaquaculture Asia2

In this issue

Sustainable AquacultureFreshwater prawn, Macrobrachium nobilii a promising candidate for rural nutrition 13Pitchimuthu Mariappan, P. Balamurugan, and Chellam Balasundaram

Snapshots of a clean, innovative, socially responsible fishfarm in Sri Lanka 14Pedro Bueno, NACA

Introduction of rainbow trout Onchorynchus mykiss in Nepal: Constraints and prospects 16Tek Bahadur Gurung*, Sadhu Ram Basnet

Tilapia seed production in Ho Chi Minh City, Southern Vietnam 23H. P. V. Huy, A. MacNiven, N. V. Tu, Ram C. Bhujel and David C. Little

Seaweed Mariculture: Scope And Potential In India 26Sajid I. Khan and S. B. Satam

Research and Farming TechniquesGrowth enhancement of carp and prawn through dietary sodium chloride supplementation 4P.Keshavanath, B. Gangadhara and Savitha Khadri

Fertilization, soil and water quality management in small-scale ponds 6S. Adhikari

Shrimp harvesting technology on the south west coast of Bangladesh 29S. M. Nazmul Alam, Michael J. Phillips and C. K. Lin

Farmers as Scientists: The “Gher Revolution” 31M.C. Nandeesha

Peter Edwards writes on rural aquaculture:Aquaculture Compendium – case study component 43

Rice-Fish Culture in China 44Fang Xiuzhen

Aquatic Animal HealthExercising responsibilities to tackle aquatic animal diseases 9CV Mohan, NACA

Application of immunostimulants in larviculture: Feasibility and challenges 19ZhouJin

Marine Finfish Section 37

What’s New in AquacultureNews 41Calendar 47

Page 13

Page 14

Page 19

Page 29

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October-December 2003 (Vol. VIII No. 4) 3

Notes from the Publisher Notes from the Publisher Notes from the Publisher Notes from the Publisher Notes from the PublisherPedro Bueno is theDirector-General ofNACA. He is theformer Editor ofAquaculture Asia

Farmers Organizations: Growing up to authority

“Apart from staying viable and being cohesive, negotiating effectively is the bestway farmers’ organizations can serve their members.”

statutory constitutions and thestructure and systems includingfinancial, to operate properly. They aregenerally professionally managedalthough no clear indication is givenon whether they are seriously engagedin organizational and professionaldevelopment other than expandingmembership or training members. Theassociations have memberships thatcomprise representatives of theindustry sub-sectors and, in one case,the input (feed and chemicals)suppliers. This multi-sectormembership endows some power inbeing able to claim a widerepresentation of the sector, and a fairamount of authoritativeness if theassociation’s opinions and adviceoffered to government or to its ownranks, are informed by science-basedsources and objective debates ofissues. Legitimacy is also seen as theassociation representing the variousscales of producers, but in particular(in the Asian context) the numeroussmall farmers.

Not surprisingly, none claimed tohave adequate funding. Theassociations raise funds throughvarious means that include organizingconferences and trade fairs, leveragingsupport from industry sponsors andgovernment, sale of or commissionfrom sale of members’ products.Running conferences, seminars andtrade exhibitions are a common andaccepted way to raise revenue bysocieties. It also gains them credibilityby being seen as providingopportunities for industry, government,scientific community and NGOs todiscuss issues dispassionately.Leveraging support from governmentthrough collaborative activities, or forgrants, is largely an acceptable meansalthough it raises a critical issue. It maygive the association greater credibilityif it maintained a great degree ofindependence. That said, most Asian

farmer associations are probably moredependent on government than theircounterparts in developed regions.This works both ways onsustainability: On the one hand,government support can come inhandy in keeping associations viableand enabling them to operate, as withgrants, support to conferences,support to promotional activities,restructuring of taxes, etc. On the otherhand, dependence on government risksfostering subservience or stiflinginitiatives to seek other ways ofsustaining the association. Somedegree of dependence on government,in the context of a developing country,is unavoidable. It has benefits, but itcould suppress initiative, at best. Atworst, it could lead to passivity andthus vulnerability to particularizeddemands. An association in such astate cannot be expected to contributewell to development processes; itwould be its own worst enemy for itsvulnerability to being used as a tool tostronger interests.

Apart from alliances or partnershipamong themselves and withgovernment, the survey did notindicate whether the associations haveformed alliances with otherassociations or societies in othercountries in or outside the region.However, some individual members ofthe shrimp associations are alsomembers of the Global AquacultureAlliance as well as the ASEANFisheries Federation. The Philippinesseaweed industry associationcooperates with international seaweedassociations like MARINALG and theInternational Seaweed Association, andis active in the ASEAN CarageenanIndustry Club. It engages experts from

At the Global Forum on AgriculturalResearch conference in Dakar, Senegalin May 2003, the farmer representativesin that conference:• Stressed the importance of farmer

participation in priority-setting anddecision making processes,particularly at the grassroots level;

• Insisted that extra efforts are neededto ensure legitimacy ofrepresentation and accountability tothe constituents; representativesmust be chosen by the farmerorganizations themselves and notappointed by other stakeholders,governments or research bodies;

• Said that extension needs to be moreeffective, and the results ofagricultural research need to bemore accessible and user-friendly tothe average farmer;

• Wanted better access to researchresults and to build on localknowledge,

• Requested assistance in buildingtheir leadership skills to ensureeffective representation, advocacyand policy formation, and improvingtheir communication andinformation-disseminationcapacities.

These conditions, if fulfilled, wouldmake farmers truly and effectivelyparticipate in the development process.But that is a big “if”. If farmers were tobe taken seriously as stakeholders inthe development process they mustorganize and, beyond building theircapacity, attain a status ofauthoritativeness. A limited surveydone by NACA in mid-2003 of differenttypes of aquaculture farmer orproducers organizations in five Asiancountries - while it was not aimed tofind support to this statement – turnedup some examples by which farmersorganizations could attain anauthoritative stature.

The surveyed associations arelegally established, have the requisite Continued on page 40...


Growth enhancement of carp and prawnthrough dietary sodium chloride

supplementationP.Keshavanath, B. Gangadhara and Savitha Khadri

Department of Aquaculture, College of Fisheries, University of Agricultural Sciences. Mangalore — 575 002. India

Success in aquaculture depends to agreat extent on sound nutritionalpractices based on the knowledge ofnutrients required by the speciescultured. It is estimated that the totalfeed cost in culture accounts for 30-70% of the production cost, dependingupon the type of culture and theintensity of feeding1. There is a limit tothe maximum growth rate beyond whichfurther increment is possible onlythrough genetic manipulation oradministration of growth promotersthat act pharmacologically to improvemetabolic and / or digestive processes2.Supplementation of diets with growthinducing substances has the potentialto be profitable because of theimproved growth rate or reducedculture period. A wide rangesubstances including hormones,antibiotics, nutrient mixtures and herbalproducts have been tested on farmedfish for their growth promotingpotential when fed at graded levels.Varying levels of success have beenreported. The fear of residuesremaining in the end product is aserious issue with consumers and canresult in restrictions being placed onaccess to export markets for entirenations.

Nearly 44% of the farmers in AndhraPradesh, a southern state of Indiahaving the highest area underaquaculture, use common salt as anadditive in fish feeds without reallyunderstanding its role in nutrition3. Theuse of common salt in aquaculturefeeds is a regular practice in Chinaalso4. A few studies have beenconducted to test the dietary role ofsodium chloride, especially in thefreshwater fish5,6. Freshwater fish takeup salt from the surrounding water tomaintain their osmotic balance, aprocess that consumes energy. Dietary

supplementation of sodium chloridecould be helpful in reducing the energyutilized for this purpose thus freeingenergy that could be channeled intogrowth instead7.

In order to study the influence ofsodium chloride (common salt) ongrowth, body composition anddigestive enzyme activity of carps andprawns, we carried out four separateexperiments of 120-day duration each in25m3 (5x5x1m) outdoor cement tankswithout soil base, at the College ofFisheries, Mangalore. We used thecommonly cultured species-rohu(Labeo rohita), mrigal (Cirrhinusmrigaia), common carp (Cyprinuscarpio) and freshwater prawnMacrobrachium rosenbergii as testsubjects. Diet (30% protein) consistingof fish meal (25%), groundnut cake(25%). rice bran (39%), tapioca flour(10%) and vitamin and mineral mixture(1%) was formulated8 to which sodiumchloride (E-Merck India Ltd.) wasincorporated at graded levels of 0%,0.5%, 1.0%, 1.5% and 2.0%. Fish ofmean initial weight ranging from 0.56 to1.60g (Table 1) stocked at 25 per tank(10,000/ha) and prawn of 1.1g stockedat 30 per tank. (12,000/ha) were fed theprepared diets once daily in themorning at 5% body weight. Feedquantity was readjusted every fortnightbased on the weight recorded at eachsampling. Water quality parameters likedissolved oxygen, pH temperature andtotal alkalinity were monitored atfortnightly intervals. On termination ofthe growth trials the activity ofintestinal and hepatopancreaticprotease, amylase and lipase wasestimated and carcass proximatecomposition analyzed. A short-termstudy was also conducted to determinenutrient digestibility, using crude fiberas the marker for calculating apparent

digestibility. The data generated forvarious parameters was subjected toanalysis of variance (ANOVA),followed by Duncan’s multiple rangetest9.

The range of different water qualityparameters monitored over theexperimental duration was withintolerable limits for the species cultured.The levels of sodium chloride thatinduced the best growth differed withthe species, it being 1% in rohu. 1.5%in mrigal and common carp and 2% inprawn (Table 1). Thus variation inresponse to sodium chloride was seeneven within closely related fish species(carps). Higher weight gain with 2%sodium chloride supplementation wasrecorded in the eel Anguilla japonica10

and juveniles of red drum7,11. Dietarysalt is reported to influence growth byincreasing food conversion efficiencyin rainbow trout12. In our study, animprovement in food conversion andprotein efficiency ratio was observed inthe case of rohu and mrigal fed optimallevel of dietary salt. Dosages above theoptimum resulted in lower weight gainand food conversion in carps. Saltappears to affect growth rate inverselywhen the level of supplementationinterferes with the balance of otheressential dietary components. Further,low digestibility and faster evacuationof food have been associated with highlevels of sodium chloride in diets13.

Dietary salt also influenced bodycomposition. Higher carcass proteinand fat was recorded in sodiumchloride fed rohu and common carp(Table 1). Increases in protein and fatcontent on feeding salt mixtures hasbeen reported in rainbow trout andcommon carp5,14. Enhanced digestiveenzyme activity was recorded in the

...continued on page 8


Table 1: Major growth parameters observed in carps and prawn fed salt incorporated diets

Species/parameter Salt level 0% 0.5% 1.0% 1.5% 2.0% Rohu (Labeo rohita) Final mean weight (g) 51.12a 62.50b 75.69c 56.96ab 51.52a Weight gain over control (%) - 22.26c 48.06d 11.42b 0.78a FCR 1.77b 1.56a 1.47a 1.79 1.85b PER 1.89a 2.16ab 2.29b 1.88a 1.82a Survival 88 88 84 88 86 Carcass protein (%) 13.03a 14.30b 14.99c 14.99c 14.08c Carcass fat (%) 7.24a 8.45b 10.13c 9.73c 7.95b Mrigal (Cirrhinus mrigala) Final mean weight (g) 57.28a 69.69b 78.46c 95.74 70.91b Weight gain over control (%) - 21.66a 36.98b 67.14c 23.79a FCR 1.76d 1.46c 1.29b 1.06a 1.44c PER 1.88a 2.30b 2.59c 3.17d 2.38b Survival 90 88 92 88 94 Carcass protein (%) 14.84b 16.72d 15.69c 15.31c 13.92a Carcass fat (%) 5.25d 3.26b 3.03 3.71c 2.15a Common carp (Cyprinus carpio) Final mean weight (g) 56.17a 61.16b 64.50bc 68.81c 66.86c Weight gain over control (%) - 8.88a 14.83b 22.50d 19.03c FCR 2.07b 2.03ab 2.00ab 2.01ab 1.93a PER 1.59a 1.65a 1.67a 1.68a 1.71a Survival 82 80 80 88 92 Carcass protein (%) 14.81a 14.88a 15.39b 16.41c 15.86b Carcass fat (%) 5.12a 4.97a 5.72b 6.90d 6.20c Freshwater prawn (Macrobrachium rosenbergii) Final mean weight (g) 23.55a 24.33a 27.05b 31.76c 36.83d Weight gain over control (%) - 3.31a 14.86b 34.86c 56.39d FCR 2.95c 2.90c 2.89c 2.76b 2.53a PER 1.13a 1.15b 1.16 1.21c 1.32d Survival 40 35 42 43 45 Carcass protein (%) 15.37a 15.44a 16.84b 15.68a 15.40a Carcass fat (%) 0.56a 0.58a 0.57a 0.53 0.51a * The average initial weights of rohu, mrigal, common carp and prawn were 1.600, 1.20, 0.56 and 1.11g respectively Note: Figures in the same row with the same superscript are not significantly different (P>0.05)

Table 2: Digestive enzyme activity* in the gut of carps and prawn fed salt incorporated diets

Species Enzyme Tissue Salt level 0% 0.5% 1.0% 1.5% 2.0% Rohu Protease Intestine 3.30a 3.07c 5.62d 4.43b 4.17b Hepatopancreas 3.37b 4.35c 4.21c 3.50b 2.51a Amylase Intestine 14.33b 15.82d 16.59c 13.98a 15.00c Hepatopancreas 11.83c 12.17d 12.46c 11.60b 11.12a Lipase Intestine 2.82a 5.03b 8.31c 3.32a 2.90a Hepatopancreas 6.32b 6.43b 6.43b 6.12b 5.21a Mrigal Protease Intestine 1.02a 1.51b 3.06c 1.95c 2.32d Hepatopancreas 2.84b 1.66a 1.91a 3.04b 3.61c Amylase Intestine 12.13a 12.27a 14.00b 15.31b 14.43b Hepatopancreas 12.83a 15.35c 12.80ab 15.02bc 12.04a Lipase Intestine 2.38a 2.23a 2.61a 2.54a 2.62a Hepatopancreas 2.14a 2.33a 3.00b 4.51d 4.00c Common carp Protease Intestine 16.62a 21.71c 23.07d 24.22c 19.31b Hepatopancreas 23.06a 22.12a 21.97a 26.87b 22.34a Amylase Hepatopancreas 23.74a 24.20a 23.73a 26.12ab 28.45b Intestine 32.16a 33.45b 33.12b 33.32b 44.56c Lipase Hepatopancreas 2.32a 5.92b 7.03c 12.43c 9.06d Intestine 11.22b 7.43a 8.05a 10.32b 11.22b Prawn Protease Intestine 2.27a 2.68a 2.69a 2.25a 0.19a Hepatopancreas 0.39a 0.66b 0.39ab 1.32d 0.92c Amylase Intestine 23.32a 22.26a 32.09c 31.13c 29.10b Hepatopancreas 9.71a 11.80b 12.63c 13.46d 16.41c Lipase Intestine 0.84a 2.10b 4.10c 4.90d 4.10c Hepatopancreas 0.40a 0.61b 0.78c 0.31a 1.19d * Enzyme activity expressed as u miles of product liberated/minute/10mg tissue protein at 28C Figures in the same row with same superscript are not significantly different (P>0.05)


Fertilization, soil and water qualitymanagement in small-scale ponds:

Fertilization requirements and soil properties

S. Adhikari

Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar 751002, India, [email protected]

Since most of the potential areas forinland aquaculture have already beenexplored in India, additional productioncan only be achieved throughsuccessful manipulation of availableresources that influence theproductivity of various aquaculturesystems. One of the main ways this isachieved is through maintenance ofadequate levels of nutrients in thepond environment. Pond managementin fish culture is mainly concerned withfertilization requirements andstrategies; and with good managementof pond soil and water quality.

Fertilization requirements offish ponds

The natural productivity of a fishculture system depends largely on theavailability of natural food organismsand on favorable environmentalconditions for the fish.

Phytoplankton, the floatingmicroscopic plants that give water itsgreen color, are the first step in thefood chain of fish ponds. Otherorganisms also feed on them andmultiply, increasing the availability ofnatural food for fish stocked in thepond. In addition to carbon dioxide(C02), water and sunlight forcarbohydrate synthesis, phytoplanktonneed mineral elements includingnitrogen, phosphorus, potassium,calcium, sulfur, iron, manganese,copper and zinc for their growth andnutrition. To promote phytoplanktongrowth and maintain the optimumnatural productivity of ponds, thewater must contain adequate amountsof these nutrients. Managing the pondsoil and water effectively can therefore

help provide an adequate amount ofnatural food for stocked fishes,promoting the healthy growth of fryand fingerlings.

Pond soil plays an important role inregulating the concentration ofnutrients in the pond water. Knowledgeof the nature and properties of pondsoil can help a farmer to developefficient management practices that willboost production. The most importantchemical properties of bottom soilinfluencing the nutrient managementpractices of ponds are as follows:

Properties of pond soils

Soil reaction (pH)

The pH of soil is one of the mostimportant factors for maintaining pondproductivity since it controls most ofthe chemical reactions in the pondenvironment. Near neutral to slightlyalkaline soil pH (7 and a little above) isconsidered to be ideal for fishproduction. If the pH is too low(strongly acidic) this can reduce theavailability of key nutrients in the waterand lower pond fertility.

Organic carbon content

Organic carbon acts as a source ofenergy for bacteria and other microbesthat release nutrients through variousbiochemical processes. Pond soils withless than 0.5% organic carbon areconsidered unproductive while those inthe range of 0.5-1.5% and 1.5-2.5% tohave medium and high productivityrespectively. Organic carbon content ofmore than 2.5% may not be suitable forfish production, since it may lead to an

excessive bloom of microbes andoxygen depletion in the water.

Carbon to nitrogen ratio

The carbon to nitrogen (C:N) ratio ofsoil influences the activity of soilmicrobes to a great extent. This in turnaffects the rate of release of nutrientsfrom decomposing organic matter. Therate of breakdown (mineralization) isvery fast, moderately fast and slow atC:N in the range of less than 10, 10-20and more than 20 respectively. Ingeneral, soil C:N ratios between 10-15are considered favorable foraquaculture and a ratio of 20:1 ornarrower gives good results.

General nutrient status

Nitrogen, phosphorus and potassiumare the major nutrients required byphytoplankton. Inorganic fertilizers canbe applied to provide these nutrients.The appropriate dosage depends onthe amount of individual nutrientspresent in the pond soil in an availableform. Generally, relatively smallamounts of potassium are needed infish ponds. However, newlyconstructed ponds or those situated onpoor soils may need potassiumapplication. The single most criticalnutrient for the maintenance of pondproductivity is the availablephosphorus content of pond soil andwater. Pond soils with 30 ppm, 30-60ppm, 60-120 ppm and more than 120ppm available phosphate (P2O5) areconsidered to have poor, average, goodand high productivity respectively.Ponds with less than 250 ppm availablesoil nitrogen are considered to have


low productivity while concentrationsin the range 250-500 ppm and above500 ppm are considered to be mediumand highly productive respectively.

Fertilization schedule ofnursery ponds

Nursery ponds

The natural productivity of nurseries isoften unsatisfactory due to adeficiency of one or more of thenutrient elements in soil and water,which may be caused by otherenvironmental conditions. Correctionof deficiencies by application ofmanures or fertilizers containing thesenutrients in suitable form and inoptimal amount is necessary toaccelerate biological production andenhance productivity. Accordingly,small shallow ponds are preferred fornurseries for easy management andmanipulation of environmentalconditions.

Use of organic manures

Both organic manures and chemicalfertilizers are widely used for improvingthe productivity of nurseries. Cowdung is the most widely used organicmanure in many areas and is typicallyapplied at a rate of 5,000-15,000 kg/hain one installment well in advance ofstocking with spawn, preferably atleast a fortnight prior. The amount isreduced to 5,000 kg/ha when mohua oilcake is used as a fish toxicant inshallow nursery ponds. Sometimes, tohasten the process of decomposition ofadded manures, nurseries are limed(CaCO3) at a rate of 250-350 kg /ha afterthe application of manure. Sometimesspaced manuring with cow dung at arate of 10,000kg/ha 15 days prior tostocking followed by subsequentapplication of 5,000 kg/ha seven daysafter stocking has been practiced forsustainable production of zooplanktonin nurseries. When more than one cropis raised, nurseries may be manuredwith cow dung at 5,500 kg/haimmediately after the removal of thefirst crop. Besides the cow dung, acombination of mustard oil cake, cowdung and poultry manure in the ratio of6:3:1 at 1,100 ppm have beensuccessfully used for the culture ofzooplankton for carp spawn.

Inorganic fertilizers

Inorganic fertilizers containing a fixedpercentage of individual nutrientelements or a combination of more thanone element are also able to enhancethe productivity of nurseries. A ratio ofnitrogen : phosphorus ration (N:P) of4:1 is considered most effective forincreased production in nurseries.Weekly application of nitrogen :phosphorus: potassium mixture (N:P:K)in the ratio of 8:4:2 ppm is suitable forincreased production of fish foodorganisms. Use of N:P:K in the ratio of18:8:4 at 500 kg/ha after liming at 200kg/ha is quite effective in enhancingthe production of slightly acidic andunproductive soils used for nurseries.

Nitrogenous fertilizers containingdifferent forms of nitrogen (amide,ammonium-cum-nitrate and ammonium)are suitable for management ofnurseries. These three forms offertilizers (e.g. urea, calcium ammoniumnitrate and ammonium sulfate) areeffective for slightly acidic to neutral,moderately acidic and alkaline soilsrespectively and a rate of 80 kgnitrogen/ha is most suitable for rearingof rohu spawn in nurseries.

Combining organic andinorganic fertilization

The combined use of both organic andinorganic fertilizers is another strategyfor increased production of either fishfood organisms or fry. The combinationof mustard oil cake and 6:8:4 :N:P:Kinorganic fertilizer on equivalentnutrient basis (at 12 kg nitrogen/ha) issuitable as compared to either organicto inorganic for nutrient management ofnurseries. However, on an equivalentnutrient basis (N:P:K) organic manure(cow dung) is the most suitablefertilization strategy for management ofcarp nurseries compared to eitherinorganic fertilizer or combined use oforganic and inorganic fertilizer.

Fertilization of rearing andstocking ponds

Acidic pond soils reduce microbialactivity and the availability of nutrientsin pond water and may renderfertilization ineffective. Therefore, theapplication of lime is the first step ofmanagement for all stages of fish

culture. Liming raises the soil pH to adesirable level (near neutral) andestablishes a strong buffer system inthe aquatic environment, improving theeffectiveness of fertilization.

Liming stimulates the microbialdecomposition of organic matter,supplies calcium to the pond, increasesnitrate content in the pond andmaintains sanitation in the pondenvironment. Generally, groundlimestone is extensively used andspread over the dry bed or broadcastover the water surface in a single doseat least 15-20 days before stocking. Onthe basis of soil pH, the followingdosages of lime are usually applied toponds. Besides initial application, somecompensatory applications of lime inthe range of 100-200 kg/ha may also bemade in the stocking pond from time totime to neutralize the acidity developedthrough application of acid-forminginorganic fertilizers and organicmanures and also when fishes arediseased or distressed.

In India, organic manures are morecommonly used than inorganicfertilizers. A variety of agriculturalwastes, including cow dung, poultrydroppings, pig manures and biogasslurry etc. can be used as organicmanures. In rearing ponds, applicationof raw cow dung or biogas slurry isobserved to give better results.Depending on the organic carboncontent of pond soil in the rearingpond, application of raw cow dung orbiogas slurry in the range of 3-7 or 5.5-12 t/ha respectively and addition of 2.5-5 t/ha/year of cow dung or 10-30 t/ha/year biogas slurry or 5-15 t/ha/yearpoultry droppings respectively instocking ponds give good results. Inrearing ponds, usually 50% of the totalrequirement is given 15-20 days prior tostocking of fry and the remaining intwo equal monthly splits during rearingperiod. In stocking ponds, on the otherhand, 20% of the total requirement isapplied initially and the rest is given inequal monthly split. But if the pondsare treated with mohua oil cake toeradicate unwanted fishes, the initialapplication of the organic manure canbe dispensed with in both the culturesystem.

The efficiency of nitrogen fertilizersin enhancing the productivity of pondsdepends largely on their forms. Thecommonly used nitrogen fertilizers are


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Growth enhancement of carp andprawn through dietary sodium chloride

urea, ammonium sulfate and calciumammonium nitrate. Among these, ureais suitable for slightly acidic to neutralsoil, ammonium sulfate for alkaline soiland calcium ammonium nitrate foracidic soil. Depending on the availablenitrogen content of the pond soil,application of 50-70 kg nitrogen/ha (i.e.108-152 kg urea/ha; 200-280 kg calciumammonium nitrate/ha; 250-3 50 kgammonium sulfate (ha) in rearing pondsand 75-150 kg/ha/year (i.e. 163-326 kgurea /ha/year; 300-600 kg calciumammonium nitrate /ha/year; 375-750 kgammonium sulfate/ha/year) in stockingponds give good results. The fertilizershould be applied in equal monthlysplits alternately with organic manurewith a gap of about a fortnight.

Single Super Phosphate (SSP) ismost commonly used as a phosphatefertilizer in fish ponds. Depending onthe available phosphate content ofpond soil, application of 25-50 kgphosphate (P2O5) /ha (i.e. 156-312 kgSSP/ha) and 40-75 kg P205/ha/year (i.e.250-468 kg SSP/ha) in rearing andstocking ponds, respectively give goodresults. To get better utilizationefficiency, phosphorus fertilizersshould be applied in weekly intervalsand the first installment should begiven seven days after initial organicmanuring.

Muriate of potash (potassiumchloride, KCl) and sulfate of potash(potassium sulfate, K2S04) arecommonly used as potassium fertilizers

intestine and hepatopancreas of thetreated fish as well as prawn (Table 2).The type of diet is known to influencethe activity of digestive enzymes15).Increased digestive enzyme activitycoupled with higher nutrientdigestibility might have beenresponsible for better utilization ofnutrients from salt incorporated diets.

Our results suggest that dietaryinclusion of salt can be beneficial.

References

1. De Silva, S.S. and Aderson. T.A. 1995. Fish Nutritionin Aquaculture. Chapman & Hall. London. 319 p.

2. Matty. A.J. 1988. Growth promotion. In: M.M.Joseph (ed.) The First Indian Fisheries ForumProceedings. Asian Fisheries Society, IndianBranch. Mangalore, India. p 13-15.

3. Veerina, S.S., Nandeesha. M.C., Rao, K.G. and DeSilva, S.S. 1993. Status and technology of Indianmajor carp farming in Andhra Pradesh, India. AsianFisheries Society. Indian Branch, Mangalore. 30 pp.

4. Yakupitiage, A. 1993. On-farm feed preparation andfeeding strategies for carps and tilapias. In: M.B. New.A.G.J. Tacon and I. Csavas (eds.) Farm-madeAquafeeds. Proceedings of the FAO/AADCPRegional expert consultation on farm-madeAquafeeds. FAO-RAPA/AADCP. Bangkok.Thailand. p. 87-100.

5. Ogino. C. and. Kaniizono, M 1975. Mineralrequirements in fish. I. Effects of dietary salt mixturelevel on growth, Mortality and body compositionin rainbow trout and carp. Bull. Jap. Soc. Sci. Fish.41: 429-434.

6. Murray, M.W. and Andrews, J.W. 1979. Channelcatfish: the absence of an effect of dietary salt ongrowth. Prog. Fish Cult. 41:155-156.

7. Gatlin. D.M. Mackenzie. D.S. Craig. S.R. and NeillW.H. 1992. Effects of dietary sodium chloride on reddrum juveniles in waters of various salinities. Prog.Fish Cult. 54: 220-227.

8. Varghese, T.J., Devaraj, K.V. Shantharam. B. andShettv. H.P.C. 1976. Growth response of commoncarp. Cyprinus carpio var. Communis to protein richpelleted feed. Proceedings of the Symposium onDevelopment and Utilisation of Indian FisheryResources. Colombo (Sii Lanka). FAQ RegionalOffice for Asia and the Far East, Bangkok, Thailand.408 pp.

9. Duncan, D.B. 1955. Multiple range and multiple F-tests. Biometrics 11: 1-42.

10. Arai, S., Nose. T. and Kawatsu H. 1974. Effect ofminerals supplemented to the fish mealdict on growthof eel Anguilla japonica. Tansuika SuisanKenkvusho Kenkvu Hokoku 24: 95-100.

11. Holsapple, D.R. 1990. The effect of dietary sodiumchloride on red drum (Sciaenops oceliatus) in freshand brackish water. Master’s Thesis. Texas A and MUniversity, College Station.

12. MacLeod. M.G. 1978, Relationship between dietarysodium chloride, food intake and food conversionin the rainbow trout. J. Fish Biol. 13: 73-79.

13. Salman. N.A. and Eddy. F.B. 1988. Effect of dietarysodium chloride on growth, food intake andconversion efficiency in rainbow trout, Salinogairdneri (Richardson). Aquaculture 70:131-144.

14. Tacon, A.G.J., Knox, D. and Cowey, C. B. 1984. Effectof different dietary levels of salt mixtures on growthand body composition in carp. Bull. Jap. Soc. Sci.Fish. 50: 12 17-1222

15. Bazaz, M.M. and Keshavanath. P. 1993. Effect offeeding different levels of sardine oil on growth,muscle composition and digestive enzyme activitiesof mahseer, Tor khudree. Aquaculture 115: 111-119.

in fish ponds. Application of 10-20 kgK20/ha (i.e. 16-32 kg KCl/ha or 20-40 kgK2S04/ha) and 25-40 kg K20/ha/year(i.e. 41-66 kg KCl/ha or 52-83 kg K2S04/ha/year) in rearing and stocking ponds,respectively give good results. Thefertilizer should be applied in equalmonthly splits.

Application of manure and fertilizershould be suspended if thick green orblue green blooms of algae develop inthe pond in order to avoid depletion ofoxygen.

Careful use of organic manures andchemical fertilizers in combination is asound strategy. Occasionaldevelopment of un-hygenic conditionsin the pond may be avoided by usingpre-decomposed organic manure. Useof excessive amounts of raw organicmanure can result in excessive bloomsof microbes during aerobic breakdownof large amount of raw organic manure,and may also caused oxygen depletion.

An understanding of chemical andbiological conditions of pond soil andwater through regular monitoringsystems and adoption of efficient andcareful management practices will leadto enhanced production of fish foodorganisms and thereby increase thegrowth and survival of fish.

Shrimp pond maintenance. Photo: U Win Latt


Exercising responsibilities to tackleaquatic animal diseases

CV Mohan, NACA

diseases in Asia are used as examplesto base some of the opinions. Beforeaddressing the three identified issues,it is necessary to briefly look into theconcept of aquatic animal diseases andhealth management in aquaculture.

Concept of disease andhealth management

Disease is the biggest threats tosustainable aquaculture. White spotdisease (WSD) in cultured shrimp andepizootic ulcerative syndrome (EUS) infish are the best examples. Asaquaculture intensifies and expands,more and more new diseases willemerge and health management willbecome very challenging. Healthmanagement can be broadly defined asapproaches taken to prevent, controland eradicate aquatic animal diseases.

For a disease to occur, the pathogenmust be able to gain entry into theculture system. Possible pathogencarriers include infected hosts (seed,brood, vectors, intermediate hosts,reservoir hosts), non-host biologicalcarriers (birds, dogs, insects, otherpredators, human beings) and fomites(water, vehicles, buckets, shoes, nets,clothing). The carriers can enter theculture system through waterborne,airborne and overland transport routes.Waterborne transport may includecontaminated water (pond effluentsand processing plant effluents) andnatural hosts in water. Airbornetransport (migratory birds, insects,wind) of pathogen carriers is a seriousconcern in open farming systems.Overland transport (infected seed,human beings, animals, vehicles, farmequipment) of pathogen carriers isoften the common route of introducingthe pathogen to the culture system.

Understanding the disease processinvolves understanding the pathogen,host and the environment. A pathogencan cause a clinical disease andmortality only when it can overcomethe defense barriers of the host and

establish in the target tissue,proliferate, cause cellular and tissuedamage and impair the function of thetarget tissue. Understanding thepathogenicity mechanisms of thepathogen, disease resistance strategiesof the host and the role of theenvironment will help to gain insightinto disease process. The concept ofdisease in an animal, how it spreadsbetween animals in a pond, andbetween ponds, farms, provinces andcountries is vital for devising measuresto minimize pathogen spread. Knowingpathogen transmission pathways helpsto better understand pond outbreaks,epidemics and pandemics. Seriousdisease outbreaks (epidemics) and croplosses are normally caused undercertain circumstances by pathogensreferred to as Category-1 pathogens.These are highly virulent, spreadrapidly, untreatable, have diverse hostrange, and threaten the very survival ofthe industry.

Principles of health managementshould be considered to keep seriouspathogens not only out of the culturedhost and environment but also out ofthe country and the region. Once thesepathogens enter and becomeestablished (endemic) it becomes veryexpensive to keep them out. Healthmanagement involves understandingand managing the host, pathogen andthe environment. Aquatic animaldisease control strategies broadlyinclude preventive and prophylacticstrategies, chemotherapy,epidemiological approaches, riskmanagement, rapid diagnostics andearly warning surveillance, biosecurityprotocols and specific pathogen free(SPF) and specific pathogen resistant(SPR) based aquaculture programs.There is considerable knowledge andexpertise on these approaches.Principles of health management needto be applied at the hatchery, farm,local, provincial, national, regional andinternational levels in order to minimizethe impact. The responsibility of health

Recognize disease as our (common)problem. Facilitate flow of science(information). Exercise responsibilities.Disease impact will be minimized.

Asia is the hub of aquaculture.Around 80% of the world’s aquacultureproduction comes from here. Diseasesare the biggest deterrents to Asianaquaculture. Health management is thebuzz-word in aquaculture and is stillthe most debated and discussed topicin meetings, seminars and workshops.The wealth of information (knowledge),expertise and resources that exist in theAsian region, on aquatic animal healthmanagement is remarkable. Significantprogress has been made in diseasemanagement in Asian aquaculture andit is well documented. However, seriousdisease problems still continue tocripple the aquaculture industry inseveral countries of the region,affecting the livelihoods of manypeople directly and indirectly. Why thisis happening? We may never be able tofully understand the underlyingreasons and they will differ fromcountry to country and opinions varyfrom person to person. Long lists offailures/constraints/limitations can begenerated. But, three reasons (that canbe called as failures) appear to belargely responsible:• Failure to recognize aquatic animal

disease as our problem bystakeholders.

• Failure to facilitate flow of science(information) among stakeholders

• Failure to exercise responsibilities bystakeholders

The term ‘stakeholders’ in this article isused very broadly to refer to all thoselinked to the industry directly andindirectly such as producers, serviceproviders, development agencies,research organizations, policy makersand consumers. This article attempts toaddress these failures, hoping tostimulate some discussions. Thegeneric analysis and commentspresented are not specific to anycountry in the region. Shrimp viral


management therefore, lies with all thestakeholders.

Recognize disease as ourproblem

Aquatic animal disease impacts onlivelihoods of aquaculture farmers andthe people who make their livingaround aquaculture (suppliers, traders,processors and others), nationaleconomies, trade and human health.Disease epizootics have a cascadingeffect on all stakeholders. Responsibleinterventions by each of thestakeholders will have a direct orindirect positive outcome on minimizingthe impact of disease. Lack of directbenefit should not be seen as adisincentive for exercising responsibleintervention. This is where the conceptof recognizing disease as “our”problem will help. Otherwise, diseasewill remain as his or their problem, butnever our problem. This should changeand it is a challenging task to bringabout this change. The flow of science-based information to the stakeholdersand demonstrating the benefits of acollective approach, will contributetowards achieving this change.Responsible interventions taken at anylevel can help the overall sector. Thebenefits of every positive reactive andproactive intervention will have atrickle down effect to the stakeholders.On the other hand, negative effects ofnot exercising a responsibility can havea dramatic devastating effect on thestakeholders. Several examples for boththese scenarios can be found in theAsia-Pacific region. Examples andlessons learnt in the region should helpstakeholders to recognize disease asour common problem.

Facilitating flow of sciencebased information

Considerable knowledge is available onaquatic animal disease process,transmission pathways, diagnosticsand management strategies.Information flows to the stakeholdersthrough various channels underdifferent circumstances for variouspurposes. This flow of information hassignificantly helped in the managementof aquatic animal diseases in theregion. The well documented, positiveimpacts, will not be discussed here.

However, upon close examination offlow of health management informationto the stakeholders, it becomesapparent that many times a messagereaches the stakeholder but not thescience behind it. It works more likepromotion of information. Unless thescience behind the message reachesthe stakeholders, we will continue tohear statements as the following whichI offer as food for thought:• “We are using screened brood

stock, our seed is disease free”• “We are using screened seed, we

can increase stocking densities”• “We have PCR testing facilities in

the country and that should solvethe shrimp disease problem”

• “Why should I spend money to treatmy pond water after losing thecrop?”

• “Processors have no role in diseasemanagement”

• “We tried everything, but still we getdisease”

• “We are using SPF animals, they areresistant, we should not have anyhealth problem”

• “We are diversifying into analternative exotic species which isresistant”

• “Our products help control shrimpviral diseases”

• “I would not mind trying treatmentsand health products to manageshrimp viral diseases”

There are many health managementconcepts that need to be correctlyinformed to the appropriatestakeholders. At the outset, it mayappear that stakeholders are wellinformed about these concepts. If onegoes down to the individualstakeholder level (farmer/policy maker),it will not take much time to realize thatvery little is known where it is mostneeded. If the science behind theinformation becomes available many ofthe responses of the stakeholderscould be different. Devisingapproaches to channel the informationand the science behind the informationto the concerned stakeholder is goingto be a challenging task. Responsibilityto facilitate flow of information restswith many people. Each of thestakeholders can play a vital link tofacilitate flow of information.Information should be provided withthe objective of creating awareness,and not just promoting hidden agenda.

Following are just a few examples ofsuch health management concepts,where science based informationshould be made available to thestakeholders.

Disease risk is inherent withaquaculture. Aquaculture free ofdisease risk is an utopian dream.Application of right strategies willminimize the impact of diseasesignificantly. There is no single riskfactor for a disease outbreak and henceno single solution. Risk identification,prioritization and management willminimise the impact of the disease.Stakeholder perception of risk andsolution should broaden and becomemore refined

Chemotherapy is not same as healthmanagement. Treating a clinicaldisease will be of little use in mostcircumstances, because damage to thetarget tissue of the animal has alreadybeen done. In addition, chemical use infood fish has potential to create foodsafety and market related concerns, anissue that is becoming increasinglysignificant in trade and food safety

PCR screened shrimp seed. Thereis no true PCR negative seed. Virus maybe present at levels below thedetection limit of the test employed orpresent in the population at prevalencelevels below what could be detected bythe sample size selected. PCRscreening, correctly applied,significantly minimizes the risk ofintroducing the pathogen into thesystem with the seed. Screened seed isnegative (only at specific probabilitylevel) for pathogens against which it isscreened, but not for other pathogensand is not resistant to any pathogens.Their use does not ensure success ifexposed to the same pathogen or otherpathogens

Shrimp Broodstock screeningbefore spawning is of little use.Spawning stress has been shown tostimulate viral replication. Broodstockwhich test negative prior to spawningmight test positive following spawning.Screening to be effective, shouldtherefore, be done after spawning. Forscreening to be beneficial, hatcherypractice should not allow mixing ofprogeny from different brooders

SPF stock. Stocks domesticated andreared in systems where the specificpathogen has been excluded.Domestication and SPF are not


necessarily same. They are notresistant to the specific pathogen.They are not free from otherpathogens. SPF stock when exposedmay become susceptible to thepathogen. Their use does not ensuresuccess if exposed to the samepathogen or other pathogens

SPR stocks. Domesticated animalsselected for their ability to survivespecific pathogen infection.

Biosecurity. Providing secucity tothe cultured organisms from exposureto pathogens of concern. Pathogencarriers (described earlier) can enter theculture system through waterborne,airborne and overland transport routes.Several recommended bio-securityapproaches are available to prevent theentry of pathogens and their carriers tothe pond, farm and the country.Adoption and implementation ofprinciples of a biosecurity canconsiderably minimise the probabilityof pathogen introduction. Severalbiosecurity principles can be veryeasily implemented at the farm/hatcherylevel. Disinfection programs at criticalpoints, screening of hosts, not sharinglabour and equipments between ponds,restricted access, safe disposal of sickand dead animals are some examples.

Epidemiology. Disease causation ismultifactorial in nature. Disease willoccur only when there is a sufficientcause. Mere presence of pathogen(necessary cause) will not always leadto disease outbreaks. WSD will notoccur without the presence of WSSV.But, mere presence of WSSV(necessary cause) will not necessarilylead top WSD outbreaks. Necessarycause, along with component causes(risk factors) become a sufficient causeto produce the disease outbreak.Epidemiological studies identify theserisk factors based on populationevidence, quantifying their effect onoutcome (disease), and assist toformulate intervention strategies.Epidemiological approaches hold greatpromise for management of aquaticanimal pathogens, which have becomeendemic and established

Import risk analysis. Scientificprocess to assist decision makingregarding importing an item (newspecies/feed/frozen shrimp). IRAinvolves hazard identification, riskassessment, risk management and riskcommunication. It should be done

before making the decision and notdone to support a decision alreadymade. Any analysis done without thereal perception of hazard andassociated risks will of little value. IRAputs the onus on the importingcountries. Responsibilities forpreventing introduction and spread ofpathogens lie also with the exporters.IRA (more appropriately, trade riskanalysis) should take into account theliabilities and responsibilities of bothimporters and exporters.

Exercising Responsibilities

Not exercising responsibilities has costthe aquaculture industry dearly andwill continue to hurt the sector, ifchanges are not brought about.Exercising responsibilities is bound tobenefit the industry substantially.What is needed is to demonstrate thebenefits, convince the stakeholdersand facilitate them to exercise theirresponsibilities. This can’t be policedand there is no need for it. Initiativesand approaches should comevoluntarily from the stakeholders, thenit is going to be sustainable.Orientation of stakeholders and raisingawareness are vital to accomplish thismammoth task.

Responsibilities to manage diseasesrests with all stakeholders concerneddirectly and indirectly withaquaculture. Principles of healthmanagement should be considered atthe hatchery, pond, farm, local,national, regional and internationallevels. Adoption of better managementpractices (BMP) for example, canminimize the impact of diseases at theproduction level (hatchery/pond/farm).Existing knowledge in the region onBMPs should be communicated to theprimary producers. Local approacheslike adoption of voluntary codes ofpractice can assist to manage diseasesat the local level. Self-help groups,farmer clubs/associations can take leadrole in developing voluntary codes ofpractice and in implementing them.Such voluntary approaches areimportant because, despite the value ofaquaculture, the support services(extension) are extremely weak in manycountries of the region.

So much is known about exoticpathogen introductions associatedwith transboundary movement of live

aquatic animals. Despite thisawareness, introductions take place. Inmany countries, stakeholder lobbiesmake strong case for new speciesintroductions largely based onperceived advantages of an exotic overa native species, often with a narrowpersonal interest. It would beproactive, if a free and fair consultativeprocess is held at the national levelinvolving all the stakeholders. Thecollective opinion emerging from suchconsultative processes will be veryuseful for right decision making. Forexample, because of the proposedadvantages of Penaeus vannamei, ithas been introduced to many countriesin Asia. Reports of taura syndrome(viral disease) and other syndromes arealready emerging from some of thecountries in the region. Despite this,many countries are eager to introducethe species. Countries in the process ofconsidering introductions, shouldseriously take into account theassociated risks, conduct IRA, seekbalanced advice (not just from a fewlobbying groups) and learn from theregional experiences, before makingdecisions. Both exporters and importershave responsibilities for preventing thespread of pathogens across countries.

Effective implementation of Nationalstrategies for aquatic animal health canminimize the risk of entry of dangerouspathogens into the country and theirsubsequent spread. Effective andpractical national strategies incountries like Australia(www.affa.gov.au) have beensuccessful to keep many seriouspathogens out of the country Nationalstrategies should assist to developskills and facilities to undertake importrisk analysis, quarantine andcertification, surveillance and diseasereporting and preparedness to dealwith disease emergencies.

Regional aquatic animal healthmanagement program of NACA isdeveloped and implemented in closecooperation and collaboration withmember governments, regionalorganizations, donor agencies andstakeholders. It facilitates sharing ofresources (information and expertise)between member governments in theregion. Regional initiatives, aim toreduce risks of aquatic animal diseaseimpacting on livelihoods of aquaculturefarmers, national economies, trade and


human health. (www.enaca.org/health)To support achievement of the goal,NACA regional initiatives aims to:• Support development and

implementation of National AquaticAnimal Health Strategies in Asia-Pacific.

• Promote widespread adoption ofbetter aquatic animal healthmanagement practices

• Promote programs for improvedsurveillance, reporting and responseto disease problems

• Facilitate harmonisation ofdiagnostic procedures andapproaches to risk assessment.

• Improve regional and internationalcooperation in aquatic animal health.

There are several internationalinitiatives, which address managementof aquatic animal diseases.International standards and guidelinesare prepared with the objective ofpromoting responsible trade andminimizing trans-boundary movementand spread of dangerous pathogens(www.oie.org, www.fao.org). Followingare some of the important instrumentsand mechanisms to support it:• OIE (world animal health

organization) Aquatic animal healthcode and diagnostic manuals

• FAO code of Conduct forresponsible fisheries

• FAO/WHO Codex Alimentarius• List of OIE notifiable diseases and

other diseases of significance• Regional/International reporting of

aquatic animal diseases• OIE Referral laboratories• Aquatic Animal Health Standards

Committee (AAHSC of the OIE)• Regional Advisory group on aquatic

animal health (AG of NACA)Adhering to international obligationsand requirements will contribute tominimize the introduction and spread ofserious pathogens

Conclusion

If some of the following examples areany indication, the future appears to bebright. Stakeholders in the region aregradually beginning to exercise theirresponsibilities to fight the commonproblem. This is encouraging and theright way forward Such initiatives canbe good lessons for stakeholders in allthe countries of the region. Voluntaryproactive approaches coming from

stakeholders are signs of a goodbeginning. Sustaining the proactiveapproaches requires commitment fromall the stakeholders. Considerableeffort and resources are required tostimulate and sustain proactiveapproaches

Hatcheries and Farms areincreasingly adopting bettermanagement practices aimed atreducing disease risks. Hatcheries/farms are willing to exercise damagecontrol strategies (in the case of whitespot outbreak) like isolation of affectedunit, removal of hosts, effectivedisinfection programs and earlywarning systems

Collective approaches in variousforms are beginning to make an impacton disease management. Farmer selfhelp groups (clubs/associations/societies) formulating strategies andguidelines to suit local needs anddeveloping voluntary codes of practiceare on the increase. Industry isbecoming open to application ofcertification programs and qualityassurance schemes (HACCP)

Extension approaches are beingbetter understood and new methodsare being developed to facilitate flow ofscience (information) to thestakeholders. Private sector isbeginning to play a lead role inenabling information flow.

Research in the area of aquaticanimal health is active in the region.Population based studies(epidemiological approaches) toidentify risks and devise diseasemanagement intervention strategies areon the increase. Rapid diagnostics areavailable to diseases of concern to theregion and dedicated efforts are beingmade to develop rapid diagnostics foremerging infectious diseases.

National strategies on aquaticanimal health management are beinggradually developed and implemented.There is evidence of countries adheringto regional and internationalobligations and requirements. Capacityfor IRA and emergency preparednessare being slowly upgraded in theregion.

Regional/international initiativesare increasingly facilitating capacitybuilding and sharing of resources.Donor and developmental agenciessupporting aquatic animal health

management programs in the region ison the increase.

The above examples of stakeholdersproactively exercising responsibilitiesis hoped to serve as useful models.Only through strong resolve andcommitment, stakeholders can ensureresponsible health management.“Exercising responsibilities” shouldbecome the new buzz-word in aquaticanimal health management

Shrimp Health Management ExtensionManual now available

This new extension manual summarisesthe farm level risk factors identifiedduring a NACA/MPEDA technicalassistance project on shrimp diseaseand coastal management. The manualsummaises farm level risk factors andpractical management practices thatcan be used to reduce risks of shrimpdisease outbreaks and improve farmproduction. The recommendations arebased on the Andhra Pradesh area,India, and are of particular relevancethere. However they can also be takeninto consideration by farmerselsewhere.

The manual was prepared by NACAand MPEDA, in association with theAquatic Animal Health ResearchInstitute, Siam Natural Resources Ltd,and AusVet Animal Health Services(Australia) and technical support fromthe Australian Centre for INternationalAgricultural Research. Download itnow, for free from:

http://www.enaca.org


Freshwater prawn, Macrobrachium nobilii apromising candidate for rural nutrition

Pitchimuthu Mariappan, P. Balamurugan, and Chellam Balasundaram

Department of Animal Science, Bharathidasan University, Tiruchirapalli 620024, India.e-mail: [email protected]

India’s abundant freshwater resourcesinclude 2.25 million hectares of pondsand tanks, 1.3 million hectares of beels,jheels and derelict waters and 1.2million km of irrigation canals and 3million hectares of lakes and reservoirs1

that strongly support inlandaquaculture activities. At the moment,freshwater prawn production in India ismainly based on capture fisheriesrather than on aquaculture. Freshwaterprawn culture has undergone aphenomenal growth in the past twodecades. Of the 100 species offreshwater prawns belonging to thegenus Macrobrachium recordedworldwide, 40 species are found inIndia. Species growing to more than15g are regarded as commerciallyimportant. Reports on the prawnfishery of the longest rivers such asGodavari, Krishna, Ganges, Mahanadi,Hooghly and Cauvery in India indicatethat the major commercial species areM. rosenbergii and M. malcolmsonii.However, other Palemonid prawns likeM. nobilii, M. lamarrei, M.scabriculum, M. birmanicum choprai,M. mirable, M. rude, M. hendersonii,M. villosimanus and M. hendersoniisupport local fisheries2,3.

The Cauvery River, the fourthlargest river in India, contributes aconsiderable amount of both fin andshellfish in the states of Tamilnadu andKarnataka. Regarding Macrobrachiumdiversity in river Cauvery sevenspecies have been recorded recently,namely: M. malcolmsonii, M. nobilii,M. scabriculum, M. lamarrei, M. rude,M. australe and M. emulum3. Amongthese prawns, M. malcolmsonii is themost widely distributed and holds firstplace in the capture fisheries andcommercial culture in and around thedelta region. Juveniles are collected enmasse during the monsoon season inLower Anicut, a seed collection center

from which juveniles are used to stockfarms in and around Tamilnadu5.

M. nobilii makes a significantcontribution to prawn fisheries since itis abundant in the entire stretch of theCauvery River. It is a diecdysiccrustacean that molts and breedsaround every 19 days. Female M.nobilii attains first sexual maturity ataround 34 mm in total length and 0.45gin weight and reach a maximum size of71mm (7.2g). The maximum size of maleis 77mm and around 13g total weight3.

An average female incubates about2,200 eggs/clutch for a fortnight6. Afterthe embryonic development hatchingtakes place in 3 to 4 batches. To avoidbatch hatching a hatcher device wasdesigned7, whichenables 70%successful,hatchingsimultaneously ina given time.Application ofeyestalk ablationincreases moltingand spawningfrequency andproduces anaverage of around5,900 eggs perprawn8. Theculture of M.nobilii has beenencouraged dueto earlymaturation andreproduction incaptivity andyear-roundbreeding whichfacilitates thecollection of egg-bearing females atany time. Eventhough it issmaller in size,this species of

Macrobrachium nobilii: The female (above) has a stouter body thanthe male (below) which sports larger chelae

freshwater prawn is accepted byconsumers and has a higher survivalrate. Differential growth between sexesencourages monosex culture sincemales grow faster than females.Hybridization with other desirablespecies may be a promising endeavorand provide a valuable contribution torural nutrition8. Egg bearing femaleshave a higher calorific value ascompared to M. malcolmsonii8, and arean excellent source of PUFA, which arefatty acids essential for human healthalong with a balanced level of aminoacids essential to the growth andnutrition of human beings. The sun-dried juveniles of M. nobilii are usedfor preparation of fishmeal and prawnfeed. M. nobilii hand collected by the


Snapshots of a clean, innovative, socially responsiblefishfarm in Sri Lanka

Pedro Bueno, NACA

If there is something worthy to mentionabout the Jaysons Farm – an 80-acrespread in Chilaw that contains a fishand shrimp hatchery, a commercialfishfeed mill, and a complex of earthenshrimp and fish ponds with over 60acres of water surface – it is that itdoes not add to the pollution load ofthe Dutch Canal, a marvelous piece ofwork done by the Dutch hundreds ofyears ago for water transport. Thecollapse – from diseases - of the shrimpfarms located along this canal has beenlargely attributed to the pollution of thewater by discharges into it fromhundreds of these farms and the intakeof the dirty water by the same farms.The Jayson’s Farm draws water notfrom the canal but from the coast,through a 4 km pipeline, thus avoidingintake of the polluted canal water. Itrecirculates the water and thereforedoes not discharge its own used waterinto the canal.

The used water recirculation systemis simple and effective. The waterchannels leading from the ponds to theused water purification pond are linedwith seagrass to absorb ammonia. The3–acre, 4-feet deep purification pondlikewise contains the grass but alsotilapia and milkfish. In fact tilapia isnow a major part of the farm’s output.Its other important function is to helpclean up the shrimp pond water and, aswith the trials being done elsewhere,for its “probiotic” effects on theshrimp. Milkfish is being tried for thesame purpose. Plans are also to raisemore of it for food. Water stays for 3days in the purification pond before itis re-used.

They employ the people in thecommunity where the farm is located,as regular and contract workers. Theyhave not had social conflicts, nopoaching, no sabotage, no laborcomplaints. Daily workers for seasonalactivities are paid more than theminimum wage and meals. The farmcontributes to community activities.

I was walked around the farm by Mr.Vasantha Jayasuriya, the youngmanaging director and chairman of theJaysons Group of Companies, which

owns Jaysons Farm. Here are thehighlights, in pictures:

Mr. Athula, the farm manager (left)and Vasantha flank me in front of astrip of mangrove bordering theJaysons Farm (1), which they have leftuntouched. Addendum: Mr. Athulawas invited by the World Bank to theWashington consultation ofstakeholders to discuss the result ofthe work of the Consortium Program ofWB. FAO, WWF and NACA in ShrimpAquaculture and the Environment inorder that he could describe theJayson’s Farm experiences and takepart in the discussions to determine thenext steps for the consortium but, asVasantha clarified, when I insinuatedthey might not have wished to revealtheir farm innovations, it was becauseAthula was unable to obtain a US visa,despite several letters from the Bankaddressed to Jaysons Farm, to Athula,and to the US embassy in Colombo,

(2) The pond is a water purificationpond using seagrass, tilapia andmilkfish as filters; (3) the waste-waterchannels are also planted with theseagrass, this one leads to thepurification ponds. Such is the clarityof the purified wastewater, I could seethe bottom of the 4-foot pond

(4) These very healthy andunblemished shrimps were taken out ofa grow-out pond that is stocked purelywith shrimp but beside a similarly sizedpond stocked with tilapia. The shrimppond water is pumped into the tilapiapond, to enable the fish to clean up thedetritus including uneaten feed, andthen gravity-flowed back (at the otherend of the tilapia pond) into the shrimppond. Addendum: Vasantha and Athulaharvested a few more of the shrimp fordinner that night at the company’sexcellent Golden Mile Restaurantlocated on a fine strip of beach inColombo. There we were joined by thethird member of the Jaysons FarmTeam, Mr. Chanaka Perera, TechnicalDirector and superintendent of the feedmill.

The farm can be contacted at:[email protected]; Fax: 94-1-716424.

women fish-folk are generally sold inthe local markets at the rate of Rs.100/kg for adults and Rs. 60/kg (1 US$= Rs.45) for juveniles in the local market.Macrobrachium nobilii is anaffordable food accessible to the poorrural people, for whom the majorcommercial species are a daydream.

Aknowledgement

This study was supported by CSIR-India, in the form of a Senior ResearchFellowship to PM.

References

1. Sugunan, V.V. and M. Sinha. 2001. Sustainablecapture and culture-based fisheries in freshwaters ofIndia. T.J. Pandian (ed), Sustainable Indian Fisheries,p43-70.

2. Chandrasekaran, V.S. and S.P. Sharma. 1997. Biologyand culture of freshwater prawns in North India.Fishing Chimes, 17: 7-9.

3. Mariappan, P. 2000. Studies on Chela biology andbehaviour of Macrobrachium nobilii with specialreference to Aquaculture. Ph.D dissertation,Bharathidasan University, Tiruchirapalli, India. pp1-67.

4. Mariappan, P., P.Balamurugan and C. Balasundaram.2002. Diversity and utilization of freshwater prawns(Macrobrachium) in river Cauvery, Tamilnadu.Zoos’ Print Journal 17(10):919-920.

Farming freshwater prawns: A manualfor the culture of the giant river prawn

FAO has released a new publication -the definitive and practical guide to thefarming of giant freshwater prawnMacrobrachium rosenbergii.

After a preliminary section on thebiology of freshwater prawns, themanual covers site selection forhatcheries, nurseries and grow-outfacilities, and the management of thebroodstock, hatchery, nursery andgrow-out phases of rearing. Harvestingand post-harvest handling are alsocovered. The management principlesdescribed are illustrated byphotographs and drawings. The manualcontains annexes on specific topicssuch as the production of larval feeds,size variation, and stock estimation.The final annex is a glossary that listsnot only the terms used in the manualitself but also those which may befound in other documents.

Editors note: This is simply the besttechnical manual I’ve seen. You candownload it for free from our websitehttp://www.enaca.org/modules/mydownloads/visit.php?cid=74&lid=350.


(3) Waste water channels are planted with seagrass for bioremediation of nutrients

(4) Water from the shrimp pond is cycled back and forth through another pond stockedwith tilapia which consume wastes and uneaten feed. Polyculture of shrimp and redtilapia, pictured here, is also conducted.

The feedmill product, a shrimp starterfeed. They also produce grow-out feed

This farm worker holds up a medium forthe production of periphyton in a tilapia-shrimp polyculture pond

(2) Water quality in the settlement pond is very good, assisted with more seagrass andalso filter-feeding tilapia and milkfish which contribute to the sustainability (andprofitability) of the farm

(1) Mr Athula, the farm manager (left) theauthor (centre) and Mr Vasantha (right)


Introduction of rainbow troutOnchorynchus mykiss in Nepal:

Constraints and prospectsTek Bahadur Gurung*, Sadhu Ram Basnet**

*Corresponding author: Agriculture Research Station (Fisheries), Pokhara, PO Box 274, e-mail: [email protected]** Fisheries Research Station, Nuwakot, Trishuli, Nepal

6,000 rivers which flow from north tosouth5. Most of these rivers are turbidduring the monsoon due to silt loadsfrom glaciers. This has been suggestedas the reason that the earlierintroductions of trout failed. However,there are many rivulets where suchhigh turbidity does not exist. Thecurrent success of trout cultivation inthe Trishuli and Godwary areassuggests that turbidity is not the majorissue and instead technologicalknowledge of trout farming is moreimportant.

At present annual fish production inNepal is estimated to be around 35, 000tonnes (2002)6, mainly from rivers,lakes, ponds, and rice field in Nepal.Anecdotally the aquaculture of carpsseems to contribute more than 95% oftotal fish production in Nepal, althoughthere are no authoritative estimates.Most production comes from the warmsouthern Terai region.

Trout prefer clean, cold andhigh oxygen water for their growthand survival, which are abundantin Nepal, particularly in the hill andmountain areas.

At present the technology forfarming Nepal’s native coldwaterfish is not well developed and fewspecies are economically viable tofarm. The introduction of aneconomically viable coldwaterspecies could allow the coldwaterresources of Nepal to be usedmore effectively. Salmonids arewell suited to commercialcultivation in cold waters and thetechnology is well developed7,8,9.There are many examples whereintroduction and aquaculture oftrout is important source ofincome9,10,11.

The first attempt to introducesalmonids in Nepal was made in1969 by importing Atlantic salmon(Salmo salar) and brown trout (S.trutta) from Kashmir, India, andrainbow trout (Onchorynchusmykiss) from the United Kingdom,and sockeye salmon (O. nerka)from Japan in 1979-80 withoutsuccess. In the third attempt tointroduce rainbow trout into Nepal,50,000-eyed eggs were brought infrom Japan12,13. Since then rainbowtrout has been bred and reared formore than a last decade14,15.

Trout was introduced in Nepalto meet many needs includingsubstitution of fish imported inhotels catering for tourists, use ofcold-water resources foraquaculture and promotion offishing tourism in hill streams. Wehave evaluated the performance oftechnological management of trout

The introduction of trout toNepal

The first origins of salmonid fish inNepal is not known. On the Indian sub-continent, Francis Day was the first tointroduce salmonids in 19831. India,Pakistan and Bhutan had successfulintroduction of trout2. In Nepal, twoearlier attempts were made to introducetrout for sports and aquaculturedevelopment before 1988, however onboth occasions the trout could notsurvive2. We are currently making athird attempt and there are indicationsthat this time trout can be promotedsuccessfully.

Nepal is a narrow country with atremendous variation in both elevationand climate across its 200km width,ranging from tropical southern plains(terai) to the alpine northernHimalayas3.

Inland water resources are abundantin Nepal4. There are approximately

Trout raceways at Godawari


under Nepal’s prevailingsocioeconomic conditions. Here wereview and briefly analyze theintroduction, and possible constraintsto farming rainbow trout in Nepal.

The third introduction ofrainbow trout to Nepal

Approximately 50,000-eyed eggs werereceived at the Godawary Fish Farm inLalitpur, Kathmandu Valley on 28December 1988 from the KobayashiFisheries Experimental Station,Miyazaki Prefecture, Japan. More than99% of the eggs survived transport andwere successfully hatched and rearedat Godawary, when water temperatureranged 8.0 to 10.5C. Hatching wascompleted after 18 days. Some of thefingerlings were sent to the FisheriesResearch Centre, Trishuli. The first fishspawned after two years7,8. Fry wereinitially fed with powdered feedsobtained from Japan but later withlocally available chicken yolk powder,buff liver and pellet crumble. The fishwere subject to intensive healthexaminations.

The farms

The Godawary Fisheries ResearchCentre was established in 1962. Thisstation is situated in central Nepal inthe Kathmandu Valley, some 1,700metres above the sea level and about16 Km southeast of Kathmandu. Theclimate is sub-tropical and cool withwater temperature falling to 8C inwinter. Pond waters reach about 26-27Cin summer but not more than 20C instreams. The farm is fed by smallstreams from surrounding hills. Thedischarge rate of the stream isapproximately 30 litres/second.

The Trishuli Fisheries ResearchCentre is some 70km north-east ofKathmandu, supplied by the TrishuliRiver. Water temperature never exceedsabove 19-20C making Trishuli suitablefor trout cultivation. The elevation ofthe farm is approximately 600 metresfrom sea level.

Rearing Systems

Trout are reared in raceways at Trishuliand Godawary Farms and fed with drypellet feed (32-40% of crude protein)and sometimes with fresh minced water

buffalo meat. The rate of feeding is 2-3% of total fish biomass for productionpurpose.

Disease

The main diseases observed are asfollows:

Fin Rot: One of most predominantdiseases. This occurred among fish ofgreater than 1kg body weight. Fish lessthan 1kg were less vulnerable but notfree of this disease. Fin rot was mostpredominant in caudal fin thoughoccasionally pectoral and pelvic finswere also affected although fish seldomdied. In newly infected parts a whitestreak appears near the caudal fin16

broadening later on as the muscle andrays start to degenerate slowly.Usually, such affected fins can healand regenerate.

Hepatoma: This was generally seenin fish bigger than 1kg body weight.This is a cancerous disease found inthe liver. About 30% of fish examinedhad the hepatoma disease. This hasalso been reported from TrishuliFisheries Research Station. Theinfected liver becomes enlarged andpale to white17. Seriously infected fishlose balance. This disease is caused byfeed contamination with aflotoxinproduced from mold, Aspergillusflavus8,17. Hepatoma arises after 4-6months of exposure18. A dose of 0.1 to0.5 ppb of aflatoxin-B1 in feed cancause the liver cancer17,18.

Fungal diseases

Fungus is mostly a problem in fertilizedeggs during incubation, and in post-spawning fish. This might be due tobruises caused by handling. In grownout fingerlings fungal diseases werehardly seen as they are not subjectedto stressful handling. The mostprominent fungus is Saprolegnia sp.This appears as ‘cotton’ and rapidlyspreads to cover the whole body,initially attacking open wounds in adultfish16. Severe cases can kill the infestedfish.

Intestinal disorders

Some intestinal disorders were seenduring the study period. The mostcommon occurrence was carcasses

with a swollen stomach. Often in suchspecimens a hemorrhage and presenceof watery fluid in the stomach wereobserved. In such cases the stomachwas totally empty indicating that thefish had not consumed any feed forseveral days before death. The swollenstomach was also associated withredness of anal opening. Suchspecimens often discharged darkyellow fluid if pressed gently atproximate end of the opening.

Physical disorders

• Blunt snout: Some individuals hadblunt or asymmetrical snout. Itseemed that the lower jaw grewnormally but upper jaw remainedundeveloped during the course ofgrowth and development.

• Twisted alevins: In 1992 someabnormal twisting occurred inunder-developed alevins. Thesewere segregated from the healthyones but did not survive long.

• Abnormal gills: Abnormal gills werefringed and not properly developed.Such gills lacked compactness andredness in appearance.

• Degenerated operculum: In somefry the rear part of operculum wasmissing and gills were notcompletely covered with theoperculum. The reasons of thedegenerated operculum were notknown.

• Blindness: Sometimes one of theeyes was absent due to unknownreasons. In the beginning the losteyes were opaque but ultimately ledto complete degeneration. Such fishwere found to lose their balance.Trout are delicate and demandhighly oxygenated waters7,8.

Past failures

The reasons for the past failures ofsalmonids in Nepalese waters are notclearly known. Management of troutfarms is labor intensive and requiresconsiderable skill, therefore a lack ofexperience (management failure) mighthave led to failure of trout rearing inpast. Fish are also susceptible todisease when reared under intensiveconditions. Commercial trout farmingrequires good hygienic to preventepidemics8.


Rainbow trout can also be rearedextensively, but its farming is mostlycharacterized by intensive feeding withhigh protein content feed for higherproduction7. The fish in such systemsbecome more susceptible to manydiseases. Among many diseases weencountered the most difficult seems tobe hepatoma. This disease is wellstudied and illustrated by Wales17.Most of the diseases can be controlled,if proper management and hygienicmeasures could be taken. To preventhepatoma, artificial feeds must beprotected from contamination byaflatoxin which is often related to poorstorage and handling of feed.

Fin rot was seen in large fish. Thismight have resulted due toovercrowding or associated withvitamin deficiency. Most diseasesmight be associated with the quality offeed stuffs and quality and quantity ofwater input in raceways.

The introduction of exotic fish maycause both positive and negativeeffects in a particular ecosystem1,19,20

but trout introduction in Nepal was notas controversial as for other fish. Thismight be due to lack of indigenous coldwater fishes for commercial farming inNepal. Before the introduction of troutin Nepalese waters, populations of acold water native fish Asala(Schizothorax sp.) was considered tobe severely impacted due to troutpredation. However, in Indian coldwater Asala was not affected much bythe presence of trout in natural waters9.In Japan, trout are commerciallycultivated from north to souththroughout the country, but trout couldbreed naturally only in NorthernProvince, Hokkaido10. This implies thattrout are not prolific breeder but need aspecific habitat to spawn in the naturalenvironment. If this would be true inNepalese conditions it is probable thattrout populations can be regulating bystocking manipulation. Theseexperiences also showed that trout andAsala can co-exist in same environmenteven if trout are stocked andsucceeded to reproduce naturally incold waters.

Conclusion

Considering vast water resourcesflowing through glaciers, pristinemountainous rivers; and marketpotential to substitute imported fish tomeet tourists demands rainbow trouthas been introduced in Nepal. Thesuccess of trout breeding, rearing andproduction, over more than one decadeshows gradual development oftechnological packages of practices,technological feasibility andperspective in Nepal. Although somediseases and management problemsrelated to hygienic feed storage wereseen this easily remedied. For wideradoption of trout farming furtherinvestment and extension activities aredesirable.

Acknowledgment

We express our gratitude to theGovernor of Miyazaki Prefecture foroffering 50,000 of rainbow trout eggsfor experimentation in Nepal. Mr. UtakaNakagawa is also thankful for provingkind support and training to the firstauthor during 1987-88. Thanks to Dr.M. K. Shrestha for kindly reviewing thepaper. We wish to thank Dr. T. Yamazakifor providing the disease identificationformat and guiding us to identify thetrout diseases.

References

De Silva, S. S. (1989) Exotics-a global perspective withspecial reference to finfish introductions to Asia. In:Exotic Aquatic Organisms. Edited by de Silva SS.Proceedings of a Workshop on Introduction ofExotic Aquatic Organisms in

Shrestha, B. C. (1997) Cold water fish culturepotentialities (in Nepali). In: Krishi (bimonthlymagazine) 34:5 (2054) Push-Magh, Fish CultureSpecial. HMG, Department of Agriculture, Nepal.

Gorkhali, P. P and J. C. Gautam (1991) Agriculture andfisheries development. In: Background Papers.National Conservation Strategy ImplementationProgram. National Planning Commission, HMG,Nepal, in collaboration with the WorldConservation Union (IUCN). Edited by Baker S etal. 1:211-238.

Bhatt, C. D. (1991) Surface and ground waterdevelopment for irrigation. Reviewer: C. K. Sharma.In: Background Papers. National ConservationStrategy Implementation Program. NationalPlanning Commission, HMG, Nepal, in collaborationwith the World Conservation Union (IUCN). Editedby Baker S et al. 1:239-258.

Shrestha, H. M. (1983) Rivers of Nepal. A preliminaryintroduction. A glimpse of water resourcedevelopment in Nepal. Nepal Digest.

Gurung, T. B. and S. K. Wagle (2000) Importance of waterquality for optimizing fish yield in Nepal: a review.Paper presented in technical seminar on informationsharing in aquaculture 2-3 Kartik, 2057, FisheriesDevelopment Directorate, Balaju, Kathmandu,

organized by Fisheries Training Centre Janakpur,Nepal.

Bardach, J. H., W. O. Ryther and Mc Larney (1972)Commercial culture of freshwater salmonids, generaSalmo, Thymallus, and Hucho. In: The farming andhusbandry of freshwater and marine organisms. JohnWilley and Sons. pp. 397-449.

Huet, M. (1975) Breeding and cultivation of salmonidsor fish culture in cold water. In: Textbook of fishculture, breeding and cultivation of fish. Fishingnews books ltd. 23 Rosemount Avenue, West Byfleet,Surray, England. pp. 59-112.

Shetty, H. P. C., M. C. Nandeesha and A. G. Jhingaran(1989) Impact of exotic aquatic species in Indianwaters. In: Exotic Aquatic Organisms. Edited by deSilva SS. Proceedings of a Workshop on Introductionof Exotic Aquatic Organisms in Asia. AsianFisheries Society, Special Publication No. 3. pp. 45-55.

Chiba, K., Y. Taki., K. Sakai and Y. Oozeki (1989) Presentstatus of aquatic organisms introduced to Japan. In:Exotic Aquatic Organisms. Edited by de Silva SS.Proceedings of a Workshop on Introduction ofExotic Aquatic Organisms in Asia. Asian FisheriesSociety, Special Publication No. 3.

Estay, F., N. F. Díaz (1994) Analysis of reproductiveperformance of rainbow trout in a hatchery in Chile.The progressive fish-culturist. 56: 244-249.

Nakagwa, U. (1998) Rainbow trout introduction inNepal (in Japanese). In: Aquaculture 6:84-86.

Yamada, T., M. K. Karna and K. R. Bastola (1998)Comparative studies on hatchability, abnormalityand advance rate of rainbow trout, Onchorynchusmykiss alevins. In: Present status of fisheries researchdevelopment and education in Nepal. Edited by: B.R. Pradhan et al 1998. Natural water fisheriesdevelopment project, Nepal Agriculture ResearchCouncil, Japan International Cooperation

Gurung, T. B. and L. S. Lama (1994) A preliminary studyon the occurrence of parasites and disease in rainbowtrout (Onchorynchus mykiss). In: Annual Report,Fisheries Research Centre, Godawary, Nepal. pp. 26-37.

T.F.R.C (2000) Annual Technical Report, published byTrishuli Fisheries Research Centre, Trishuli,Nuwakot, Nepal.

Davis, H. S. (1961) Culture and diseases of game fishes.University of California Press. Berkeley and LosAngeles, California.

Wales, J. H. (1961) Hepatoma in rainbow trout. In: Asymposium on diseases of fishes and shellfishesprepared by the Symposium Committee: Stanislas F.Snieszko, Chairmen and editor. Special PublicationNo. 5. American Fisheries Society Washington D.C

Halver, J. E. (1972) Fish Nutrition, Academic Press,London Ltd.

Thia-Eng, C. (1989) Address of Dr. Chua Thia-Eng,President of the Asian Fisheries Society. In: ExoticAquatic Organisms. Edited by de Silva, S. S.Proceedings of a Workshop on Introduction ofExotic Aquatic Organisms in Asia. Asian FisheriesSociety, Special Publication No. 3. pp. vii-viii.

Waples, R. S. (1995) Genetic effects of stock transfer offish. In: Protection of Aquatic Biodiversity. PhilippDP, JM Epifanio, JE Marsden, JE Claussen, RJWolotira (editors). Proceedings of the WorldFisheries Congress, Theme 3. Oxford and IBHPublishing Co. Pvt. Ltd; New Delhi, India.


Application of immunostimulants inlarviculture: Feasibility and challenges

ZhouJin

Shanghai Fisheries University, E-mail: [email protected])

In this respect, fish are reliant onpassive immunostimulation frommaternal antibodies, and thismechanism has been shown in tilapias(Mor et al, 1990; Sin et al 1994). In anygiven species, size rather than ageseems to be the most criticaldeterminant of the development ofimmunity. For example, in salmonids,memory-dependent immunity has beenachieved for sizes > 0.26g (8 weeks ofage), whereas in carp it was acquired at

(Eills,1988). It is therefore possible thatduring the stages when the lymphoidorgans are developing, the maincellular defence is by the phagocytepopulations within the integument(Ellis 1988).

The nonspecific or innate immunesystem is regarded as the first line ofdefence in animals. Furthermore, itseem that the microbial problems inlarviculture are most likely due toopportunistic bacteria rather thanspecific pathogens (Munro etal,1995).This emphasizes theimportance of nonspecific defencesystem for larvae under intensive

hatchery conditions, and the needfor more knowledge of the

ontogeny and functionality ofthe nonspecific immune systemof larvae.

Immunostimulation oflarvae: Possibilities

and constraints

Immunotherapy comprises allmethods that utilize

immunological principles toprevent or treat disease. In human

and veterinary medicine,immunotherapy has already beenapplied but it is still regarded as an areafor growth. Methods of transplantingimmunologically active cells ortransferring immunoglobulins are notrelevant to larviculture, and thereforenot treated further in this study.Immunomodulation, and in particularimmunostimulation, seems to be themost suitable immunotherapeuticmethod for larviculture in theforeseeable future.

Immunomodulation may be direct atboth specific and nonspecific immunity.Vaccination is probably the best-knownmethod of specific immunostimulation,and it entails increased resistanceagainst a specific antigen (pathogen).

Immunostimulants are valuable for thecontrol of fish diseases and may beuseful in fish culture. Microbialpathogens are one of the mainproblems in the rearing of larvae. It istherefore important to develop methodsfor establishing microbial control at allstages of the cultivation progress. Onepossibility is immunostimulation, whichincludes methods of enhancing thecapacities of the specific and non-specific immune systems. There aremany experiments on nonspecificimmunostimulation of fish that suggestthat the method has considerablepotential for reducing losses inaquaculture, both during larval andon-growing stages. So, on onehand, we can say that use ofimmunostimulation inlarviculture is possible. On theother hand, due to the smallsize and fragility of larvae thedevelopment of methods toadminister the stimulant, andthe adaptation of methods fordetecting the response of theimmune system is full ofchallenges. The aim of the paper isto evaluate the status and thepotential for immunostimulation as anelement in the strategy for solvingmicrobial problems in larviculture. Thefocus will be on fish, but the ideas arealso applicable to other groups oforganisms relevant to aquaculture.

The characteristics of thelarval immune system

The main function of the immunesystem is to protect the animal againstdisease causing microbes. The immunesystem comprises both nonspecific andspecific components, and involvesboth cellular and humoral factors. It iswell known that larvae do not have theability to develop specific immunityduring the early stages of development.

9-10 weeks (Ellis 1988).The nonspecific immune system is

probably the main defence againstmicroorganisms in larvae. Although weunderstanding of the components ofthe innate defence system of fish isgrowing, relatively little is known aboutthe functioning and the ontogeny ofthe general immune system in larvae(Olafsen et al 1993). In the few fishspecies that have been studied, themajor lymphoid organs are not fullydeveloped at the time of hatching, andthe phagocytic activity is mainlyassociated with gills, skin and gut


Fingerlings of round herring

Applying oral peptidoglycan, a very important immunostimulant

Nonspecific immunostimulation refersto a condition in which the immuneresponse is changed to a conditionwith higher response towards a varietyof antigens. An example of nonspecificimmunostimulation is macrophageactivation. An immunostimulant may bedefined as an agent that stimulates thenonspecific immune mechanisms whengiven alone or the specific mechanismswhen given with an antigen. It isbelieved that in eggs and larvae theeffects of immunostimulation may be toenhance the “inheritance” of animmune defence, but they last for onlya short period. A special case ofimmunostimulation may be to enhancethe immune defence of larvae throughimmunostimulation of the mother(maternal immunity).

Many different types or groups ofsubstance are known to act asimmunostimulants, such aslipopolysaccharride (LPS),b-1,3-glucan,peptidoglycan and so on. It isimportant to consider the specificity ofimmunostimulants for two reasons.First, a stimulation of an immunesystem may be too intense, and mayharm or even kill the host. This is well-known in humans, where the activationcaused by LPS in connection withinfections may cause septic shock anddeath (Morrison et al,1994). Secondlyknowledge of the functions of differentimmunostimulants may be used tostimulate those parts of the immunesystem that may be more relevant incertain situations.

Three factors are essential toconsider in the design of an

immunostimulation strategy. First, it isimportant to remember that in mostcases we do not have a specificmicrobial problem, but rather a generalone involving large numbers of bacteriaand a high proportion of opportunisticspecies. Secondly, the immune systemof larvae is poorly developed,consisting mainly of nonspecificdefences. Thirdly, the immune defencesof maternal origin will be significantonly during the earliest developmentalstages. Although this period and hencethe maternal immune defence may becritical, aquaculturists cannot rely on

this part of the immune defence of thelarvae alone. These three factors meanthat research aimed to developmethods for immunostimulation oflarvae should place the highest priorityon stimulation of the nonspecificdefence system. This work shouldprincipally involve stimulation of thenonspecific defence of the larvae itself,and should also include stimulation ofnonspecific maternal defences ifpossible. In cases where specificpathogens are known to causeproblems, stimulation of the specificdefence may be considered throughimmunization of the broodstock.

Immunostimulation of larvalfish: Nonspecific defences

Newly hatched fish larvae have notacquired specific imune defence, butmaternally transferred specificimmunity may also be of significance(Mor and Avtalion, 1990). Contrary toearlier conceptions, there are recentobservations indicating that larvaestart to develop immunocompetencerelatively early. Bergh et al (1995)observed presence of lymphoid cellsearly in the first feeding period ofAtlantic halibut. Padros and Crespo(1996) have described development oflymphocytes in lympoid organs ofturbot at the time around


00. 010. 020. 030. 040. 050. 060. 070. 080. 090. 1

0 5 10 15 20 25 30hour s

ng p

oly

man

nuro

nic

acid

*nau

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Stability of the non-specific immunostimulant poly mannuronic acid in Artemianauplii that had been grazing on alginate microcapsules containing the 14C-labelled stimulant, after tranefer to larval tank condition. The experiment wasrun with two replicate cultures (Skjermo and Vadstein, unpublished results)

metamorphosis. These findings clearlyindicate the importance of nonspecificimmune defence in the larvae stages.

A number of studies have beenperformed on stimulation of thenonspecific immune defence of bothfresh and seawater fish, describing awide range of attractive methods forprophylaxis in aquaculture (Vadstein1997). Most investigations have so farinvolved juvenile or adult stages, butdevelopment of strategies fornonspecific immunostimulation inculture of the earliest stages of fishmay have considerable potential(Vadstein 1997).

During their 4-5 week yolk sacperiod larvae of Atlantic halibut areexposed to stress from high numbers ofopportunistic pathogenic bacteriacompared to what they experience intheir natural conditions (Hansen 1993).Use of nonspecific immunostimulantshas been shown to enhance viability ofhalibut yolk sac larvae during 4 weeksincubation, from on average 10%survival in control groups to 52%survival in treated groups (Vadstein etal 1993a). The immunostimulant used inthe halibut larvae experiment was analginate rich in mannuronic acidpolymers, which is stimulatory towardshuman monocytes (Espevik et al 1993)and fish. The immunostimulant (termedFMI) was administered to theincubation water of small, stagnantunits, and the larvae were thus longterm exposed during the whole yolk sacperiod. The route for uptake was notstudied, but stimulation of thenonspecific defence of both the skinand gut surfaces can be suggested.Immersion of marine larvae inimmunostimulants at an early pre-feeding stage is therefore believed tobe a suitable technique forimmunostimulation, preferably inperiods with stagnant or low waterexchange conditions. The techniquemust be carefully prepared for theactual organism, regardingimmunostimulant, concentration,duration of immersion, developmentalstage of larvae and frequency foradministration of the stimulant.Immersion has been documented asefficient also for carp (Siwicki et al1988),even though oral administrationor injection seem to be more efficient(Vadstein,1993a).

A technique for administration ofimmunostimulants via live foodorganisms has been developed. Theimmunostimulant is immobilized inalginate microcapsules (2-30um) andingested by live food organisms, suchas rotifers or Artemia nauplii. Fig 1shows the content of polymannuronicacid in Artemia nauplii after grazing onalginate beads, and illustrates therelatively rapid decrease in contentafter transfer of the nauplii to the larvaltanks. The regime for feeding the fishlarvae is therefore important forsuccessful use of live food organismsfor administration of immunostimulantsto larvae. The method is non-stressingand very suitable for prophylactictreatment in the earliest stages in larvalfirst feeding. Theefficiency of themethod wasdemonstrated intwo experimentswhere FMI wasadministered toturbot fry viaalginate beds andArtemia two daysprior to achallenge with afish pathogenicVibrioanguillarum.Mortalityreductions of 39and 48% wereobtained instimulated vsnon-stimulated An export-oriented farm - mainly turbot and flounder

groups (Skiermo et al, 1995). Progressin the development of formulated firstfood for marine larvae, and entrappingimmunostimulant in food particlessuitable for larvae is therefore achallenge.

Challenges in future

As the review above demonstrates,more knowledge is needed before astrategy for specific and nonspecificimmunostimulation can be developedfor larviculture. The few studies onstimulation of specific maternalimmunity and the more numerousstudies of stimulation of nonspecificdefence of fish suggest that there is agood possibility of developing efficientmethods for immunostimulation in


to funds comparable to those availableto human medicine; therefore researchshould focus on the immunostimulantsthat have already been intensivelystudied in other areas. The knowledgeand the spin off from these other areasrepresent a considerable resource foraquaculture research.

For stimulation of maternalimmunity, it is important to clarifywhether it is possible to stimulatenonspecific immunity in a way that isrelevant to larviculture. Due to theshorter duration of such stimulation,nonspecific stimulation through thematernal pathway may not be feasible,but a clarification of this point isnecessary before and final conclusioncan be drawn. Stimulation of specificimmunity is the most promising methodfor applying maternal stimulation. As ageneral method, it is not suitable, but inthe cases where specific problem

organisms have been identified, itshould be possible to evaluate thepotential of the method. Such anevaluation should include optimizationof immunization procedures, andevaluations in both challengeexperiments and under productionconditions. It is important thatevaluations are done under both setsof conditions, because even ifstimulation of maternal immunity doesnot have significant positive effects ina challenge test, in which the problemorganism occurs at high densities, itmay do so under productionconditions. The method is notrestricted to bacteria (Sin et al 1994).

The challenges related tononspecific immunostimulation of thelarva itself are more diverse than thoserelated to maternal immunity. Reliablelarval experiments are expensive, due tothe complexity and the poorreproducibility of such experiments.More information is required on thedevelopmental stage in whichimmunostimulation is possible, and forthese additional evaluation criteriaother than challenge tests will beneeded. The research on the ontogenyof the nonspecific immune systemshould focus not only on thedevelopment and the functioning ofrelevant organs, but should alsoinclude studies of the immune systemin the integument. The development ofmethods of assessing stimulation is aspecial challenge; due to the small size

of larvae. Priority should be given tothe establishment of methods fordetermining parameters that occur earlyin the cascade of reactions triggered byimmunostimulants. The researchdirectly related to the establishment ofan immunostimulation strategy shouldinclude evaluation of administrationprocedures, dose-responserelationships, and the evaluation of theduration of stimulation.

Prospects

Immunostimulation is one element in astrategy to achieve microbial control.Direct stimulation of nonspecificimmunity and stimulation of specificdefence mechanism of maternal originseem to be the most promising methodsfor larvae. Based on availableknowledge, it is concluded thatalthough this technique is still in itsinfancy, immunostimulation of fish hasa considerable potential for reducinglosses in aquaculture, during bothlarval and on-growing stages. Theexperience with larvae, however, is verylimited. More research anddevelopmental work onimmunostimulation of relevance forlarviculture is needed ifimmunostimulation would contribute tothe development of the aquacultureindustry.

Reference

1. Bergh, Hordvik, I; Glette, J. 1995. Ontogeny of IgMsynthesis and IgM bearing cells in the Atlattichalibut, Hippoglossus hippoglossus. Larvi ’95European aquaculture society gent specialpublication No 24 P 501

2. Ellis, A.E 1988. Ontogeny of the immune system inteleostfish. General principles of fish vaccination.Academic press. P. 20-31

3. Espevik, T. Otterlei, M. Skjak, B et al. 1993. Theinvolvement of CD 14 in stimulation of cytokineproduction by uronic acid polymers. Eur. J. Immunol.23. 255-261

4. Hansen, G.H. 1993. Bacteriology of early life stagesof marine fish with special reference to aquacultureof new cold water species. Dr.Scient. thesis,University of Bregen, Norway.

5. Mor, A. Avtalion, R. 1990. Transfer of antibody fromimmunized mother to embryo in tilapias. J. Fish. Biol.37. 249-255

6. Morrison,D.C. Dinarello, C. Munford R et al. 1994.Current status of bacterial endotoxins. ASM News60. 479-484

7. Munro, P. Barbour, A. Birkbeck, T.H. 1995.Comparison of the growth and survival of larvalturbot in the absence of culturable bacteria withthose in the presence of Vibrio anguillarum, Vibrioalginolyticus or a marine Aeromonas sp. Appl.Environ. Microbiol. 61. 4425-4428

8. Olafsen,J.A. Roberts,R.J. 1993. Salmon diseases.Salmon aquaculture. Fishing news books. Oxford PP.166-186

9. Padros, F. Crespo, S. 1996. Ontogeny of the lymphoidorgans in the turbot Scophthalmus maximus: a lightand electron microscope study. Aquaculture. 144.1-16

10. Sin, Y.M. Ling, K.H. Lam, T.J. 1994. Passive transferof protective immunity against ichthyophthiriasisfrom Vaccinated mother to fry in tilapias, Oreochromisaureus. Aquaculture. 120, 229-237

11. Siwicki,A.K. Korwin,K.M. 1988. The influence oflevamisole on the growth of carp (Cyprinus carpioL.) larvaeJ.Appl.Ichtyol. 4. 178-181

12. Skjermo,J. Vadstein, O. 1993. Characterization of thebacterial flora of mass cultivated Brachionusplicatilis. Hydrobiologia. 255/256. 185-191

13. Vadstein, O. Olsen,Y. Salvesen I et al. 1993. A strategyto obtain microbial control during larvaldevelopment of marine fish. Fish farming technology.A. Balkema publishers. Rotterdam.. P. 69-75.

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Tilapia seed production in Ho Chi Minh City,Southern Vietnam

H. P. V. Huy, A. MacNiven, N. V. Tu, Ram C. Bhujel and David C. Little

method of seed production.Perceptions of seed quality vary withgrow-out farmers, traders and nursers.Inconsistent tilapia seed quality wasperceived to be a problem by thetraders in Southern Vietnam, especiallythose distributing seed to the MekongDelta that involves longertransportation times. Farmers were alsoof the opinion that the poor seedquality is a main factor causing poorfish productivity. The causes of theperceived poor quality could be due topoor pond management, lack oftechnical know-how, long distancetransportation, poor handling and/orpoor broodstock quality. Therefore,tilapia fry were collected for an on-station research at the University ofAgriculture and Forestry to comparethe quality and to identify theassociated factors. A survey was alsoconducted to provide supplementaryinformation to the research trial. It wasfelt that this information on it’s ownwould be useful for those who areinvolved in planning, research andeducation in Vietnam and other parts ofthe world.

Survey method

A questionnaire survey was conductedwith 20 fry producers who providedseed that were used in an on-stationnursery trial. These farmersrepresented a sample of about 10% ofthe hatchery operators in District no. 8of Ho Chi Minh City A brief face-to-face interview was carried out witheach hatchery operator to gatherinformation on the source of seed,broodstock and nursery management.The survey covered both socio-economic and technical issues relatingto the quality of fish seed.

Production system and thepractices

Observation during the surveyrevealed that most farmers use at leasttwo ponds that are filled with waterfrom the municipal sewage canals,which pass through the district. Beforefilling the ponds, farmers drain and drythem, and use pesticides to killpredators. Some farmers also use quicklime (@7-10 kg/100m2). The averagepond size ranges from 1,000 to 2,000m2. As sewage water is rich innutrients, growth of natural food orplankton occurs within a week or so.Sewage varies in strength seasonally.As it is stronger in the dry season, itneeds settlement before use. After theappearance of sufficient natural food,tilapia brooders are stocked into thepond i.e. Pond 1 (Figure 1). Normallyfry are observed after about threeweeks of broodfish stocking. Afterspawning the broodstock aretransferred to the other pond i.e. Pond2 leaving the fry behind in the Pond 1.Some farmers claim that if broodfish areseined by 4-5 persons early in themorning when the fish are surfacingbecause of low dissolved oxygen, 90%of the broodfish can be removed. Allthe fingerlings are harvested afterabout 10-30 days by seining anddraining of the pond. The seed aregraded at harvest into 5 sizes (meanindividual weights 6, 8, 10, 12 and 14 g)and the ratio of seed size harvesteddepends on the nursing period. Theduration of cycles varies with demand.If the demand is low the operator tendsto lengthen the nursing periodresulting in larger seed. The first pondis again prepared over a 10-day periodfor the next breeding cycle to stock thesame broodfish kept in the secondpond or the new breeders. The newbreeders are the fingerlings producedin these ponds and nursed separatelyin other ponds. In this way the cycle oftilapia seed production continues. Themajority of seed producers use 3-4

Climatic conditions in Vietnam varygreatly as the country stretches fromthe South of China in the North to theGulf of Thailand in the South. In thenorth, temperatures sometimes dropbelow 10ºC during winter, and tilapiasneed careful over-wintering to survive.In the south of the countrytemperatures are suitable year-round.In Southern Vietnam especially aroundHo Chi Minh (HCM) city, tilapia seed isproduced in sewage-fed ponds usingmethods that have been developed byfarmers themselves. The majority oftilapia seed used in the provincesaround HCM and on the Mekong Deltaare produced in these systems. Tilapiaseed production has become a part ofdiversified suburban agriculture systemand appears to have evolved as abyproduct of food-fish production.

Culture of fish in ponds fed withwastes from latrines has been atradition in Southern Vietnam,especially stocking of Pangasius seedcollected from wild. Stocking ofhatchery-produced seed is more recentphenomenon that has been driven bythe market demand in and around theHCM city where aquaculture isincreasingly commercial in nature; 40%of the fish farmers say that aquacultureis their main source of income1.Although Chinese and Indian carps,silver barb, gouramies and hybridcatfish are cultured in SouthernVietnam, the most preferred species aretilapia and the common carp. Hatcherytechniques and infrastructures for all ofthese species are now well developed.Specialized nursing and tradingactivities have become wellestablished. Both wholesalers andretailers are important players in thetrading of fish seed in SouthernVietnam. While this has improved thesupply of fish seed to farmers, it hasled to a lack of contact and reducedinformation flow between hatcheryoperators and food fish farmers. Forexample food fish farmers understandlittle about the source of broodfish or


Figure 1. Steps involved in tilapia seed production in HCM City, Southern Vietnam

Selected new generation broodstock

Pond No. 1

Spawning takes place

Fry nursing

Fry harvest

Pond No. 2

Spawning takes place

Fry nursing

Fry harvest

Sewage

Pond filling with sewage water after pond preparation

Broodstock

Broodfish stocking after pond becomes green

Transfer of broodfish after spawning

Fingerlings for sale Fingerlings for sale

Middlemen

Grow-out farmers

cycles per year; however, some of themcan produce up to 8 cycles a year. Themajority of farmers change the watereither continuously or at least 2-3 timesper culture cycle.

Socio-technical information

The survey results showed that themajority (60%) of the tilapia fryproducers have considerableexperience (mean of 12 years (range 5-24 yrs). Almost all (95%) of thehatchery operators produce tilapia seedas their main occupation, utilizingmostly family labor. However, at least

one-third of the total producers havesome alternative source of income suchas sale of fruits from the trees grownon the dikes or from family memberswho are employed off-farm. Most of thefry producers (85%) feel they lacktechnical information. The majority(75%) of the seed producers learnedthe techniques from their neighborsand none has had any training even ongeneral fish culture. A small percentage(15%) of the seed producersinterviewed learnt by themselvessuggesting that the techniquesemployed are relatively easy to adopt.Most of the seed producers (90%)

recognise Nile tilapia, and 60% use apure strain initially imported anddistributed by AIT AquacultureOutreach in 1993. About 40% producehybrids, but 75% wanted to try toproduce pure Nile tilapia. A minority ofproducers (20%) were aware of all-maletilapia production techniques. Only afew seed producers (15%) are planningto expand their operations while themajority (70%) were satisfied with theircurrent level of business and said thatthey would continue rather than sellingoff their land, which is a commonpractice in such suburban farmingareas.


Parameters Special features 1. Stocking density ranged from 0.7 to 1.1 kg (average = 0.9 fish/m2) 2. Sex ratio male:female (at stocking) 1:2 - 8 with an average of 1:5 3. Broodfish weight male = 99.5 g and female = 101.5 g 4. Broodstock feeding rice-bran (80%) only @1.5 mt/ha/cycle or with duckweed (20%) 5. Fry feeding rice bran only 6. Fingerling holding system hapas in tank to hold the over-produced seed but they don’t feed them

anything during this holding period 7. Annual fingerling production 400 – 5,500 kg (i.e. 0.2 – 3.3 million fingerlings)/per family) 8. Fingerling sale Most of the hatchery operators (90%) sell their fry to middlemen in the

local district market i.e. Trong Vuaong 9. Fingerling price 1 US$/kg (~ 0.17 cent/fingerling)

Table 1: Characteristics of tilapia seed production system in Ho Chi Minh City, Vietnam

Most of the respondents hadn’treceived any complaints against thequality of fry they sell. Their customersare mainly fingerling traders. Out of 20fry producers interviewed 19 havemaintained or increased their level offry production over the last five years.Only one producer has decreased theproduction. The main constraints tofurther increasing production are timeavailability, and the cost of feed andbroodstock. Feed (90% of therespondents) and broodstock quality(65% of the respondents) wereconsidered the most important factorsin improving productivity. Varioustechnical features of the systempracticed by the farmers are presentedin Table 1 and Figure 1.

Implications

As the system used by these peri-urban Vietnamese farmers is, largely,self-sustaining, almost all of the seedproducers have adopted it as their mainbusiness. Seed quality was not anissue for these hatchery operators; anyfeedback they received gave them nocause to change their practices. On theother hand, there might be someproblems but complaints come up tothe middle-men level only since theyhave no direct contact with the end-users or the small farmers, and theyonly deal with middlemen whotransport the seed throughout theregion. These farmers had not beentrained or supported with appropriateknowledge and skills. We can see,however, that a successful farmer canhave an important impact onneighboring farmers through theexisting diffusion mechanism, ornetwork for innovation. However, theperception of the hatchery customers

on the Mekong Delta is different fromthose in the provinces around HCMcity. On the Mekong Delta, farmersperceived the quality of tilapia seed tobe poor whereas this was not so strongcloser to their site of production. Anearlier report1 concluded that the poorquality of the seed produced in thesame system was related to poortransportation and handling conditionsof seed rather than genetics per se.Nevertheless, inconsistent supply ofquality seed has led commercial cageoperators on the Delta to regularlyimport high quality mono-sex fry fromThailand. The continuance of thissewage-based hatchery system is likelygiven current prices and input costsbut a market for seed of higher qualityhas emerged for which alternatives arerequired. Use of sewage requiresfrequent sediment removal from pondsif productivity is to be maintainedwhich is labor intensive but is currentlya cost effective method to bothproduce a value-added crop and, in theprocess, treat human waste. Openpond-based systems make productionof pure, improved stocks difficultbecause of contamination with feralfish. Moreover hormone treatment offish removed from such systemsproduces very inconsistent results.Poorer access to sewage as municipalsanitation projects come on stream isalso likely to impact on the system.

Realizing the benefits of tilapia as asource of protein and income for therural poor, and as a potentially lucrativeexport commodity, the Vietnamesegovernment is now actively promotingtilapia production through activitiesunder their Fisheries Master Plan. Thesewage based system produces anestimated 200 million of fry annually ina single district (no. 8) in Ho Chi Minh

city and provide employment to about200 families; the practice also occurs inother areas of the peri-urban zone.However, to fulfill the potential demandfor high quality tilapia fry, a largerscaling up in the capacity of hatcherieswill be needed to produce and supplyseed to meet such ambitiousgovernment targets. The existingsystem will require improvement toremain competitive with other hatcherysystems in the future and to contributeto the increase in production planned.This will require active support forcurrent and new sewage hatcheriesfrom government agencies responsiblefor both aquaculture development andurban sanitation.

Aknowledgements

This article is an output of the Fishseed quality project in Asia (R7052)supported by the DFID-AFGRP. Theauthors were associated with theproject while serving their owninstitutions. H.P.V. Huy and N.V. Tu arewith University of Agriculture andForestry (UAF), Thu Duc, Ho Chi MinhCity, Vietnam, A. MacNiven and Ram C.Bhujel serve Aquaculture and AquaticResources Management (AARM),SERD, Asian Institute of Technology(AIT), Thailand, and David C. Little iswith the Institute of Aquaculture (IoA),University of Stirling, FK9 4LA,Stirling, UK. (For more information,please contact: David C. Little [email protected] or Ram C. Bhujel [email protected]).

Reference

1. AIT/CAF, 2000. Fish seed quality in SouthernVietnam. State of the System Report. AquacultureOutreach Programme, AIT, Bangkok. 28pp.


Seaweed Mariculture: Scope And PotentialIn India

Sajid I. Khan and S. B. Satam

College of Fisheries, Dr. B. S. Konkan Agricultural University, Ratnagiri

of emulsions, suspensions and foams,and control of crystal growth2.

Chemicals from brown seaweedssuch as alginic acid, mannitol,laminarin, fucoidin and iodine havebeen extracted successfully on acommercial basis. As the alginates canabsorb many times their own weight ofwater, have a wide range of viscocity,can readily form gels and are non-toxic,they have countless uses in themanufacture of pharmaceuticals,cosmetic creams, paper and cardboard,and processed foods.

Being rich in minerals, vitamins,trace elements and bioactivesubstances, seaweeds are calledmedical food of the 21st century.Digenea (Rhodophyta) produces aneffective vermifuge (kainic acid).Laminaria and Sargassum specieshave been used in China for thetreatment of cancer. Anti-viralcompounds from Undaria have beenfound to inhibit the Herpes simplexvirus, which are now sold in capsuleform. Research is now being carried outinto using Undaria extract to treatbreast cancer and HIV. Another red algaPtilota sp. produces a protein (a lectin)that preferentially agglutinates humanB-type erythrocytes in vitro. Somecalcareous species of Corallina havebeen used in bone-replacementtherapy3. Asparagopsis taxiformes andSarconema sp. are used to control andcure goiter while heparin, a seaweedextract, is used in cardiovascularsurgery.

Global seaweed productionand trade

Currently there are 42 countries in theworld with reports of commercialseaweed activity. China holds first rankin seaweed production, with Laminariasp. accounting for most of itsproduction, followed by North Korea,South Korea, Japan, Philippines, Chile,

Norway, Indonesia, USA and India.These top ten countries contributeabout 95 % of the world’s commercialseaweed volume. About 90 % seaweedproduction comes from culture basedpractices. The most cultivated seaweedis the kelp Laminaria japonica, whichalone accounts for over 60 % of thetotal cultured seaweed productionwhile Porphyra, Kappaphycus,Undaria, Eucheuma and Gracilariamake up most of the rest to a total of 99%. The most valuable crop is the redalga Nori (Porphyra species, mainlyPorphyra yezzoensis), used as food inJapan, China and Pacific.

According to FAO4, between 1981and 2000, world production of aquaticplants increased from 3.2 million tonsto nearly 10.1 million tons (wet weight),upholding US $ 6 billion world trade in2000, compared to US $ 250 milliontrade in 1990. The contribution ofcultured seaweeds is 15 % of totalglobal aquaculture volume (45,715,559tons) or nearly 5 % of total volume ofworld fisheries production (141,798,778tons) for 2000. The seaweeds that aremost exploited for culture are thebrown algae with 4,906,280 tons (71 %of total production) followed by the redalgae (1,927,917 tons) and a smallamount of green algae (33,700 tons).

East and South-East Asian countriescontribute almost 99 % culturedproduction, with half of the production(3 million tons) supplied by China.Most output is used domestically forfood, but there is a growinginternational trade. The Porphyracultivation in Japan is the biggestseaweed industry, with a turnover ofmore than US $1.8 billion per annum.Total EU imports of seaweed in 2001amounted to 61,000 metric tons with thePhilippines, Chile and Indonesia as thebiggest suppliers. Significantquantities of Eucheuma are exported bythe Philippines, Tanzania and Indonesiato USA, Denmark and Japan. The

Seaweeds are macrophytic algae, aprimitive type of plants lacking trueroots, stems and leaves. Mostseaweeds belong to one of threedivisions - the Chlorophyta (greenalgae), the Phaeophyta (brown algae)and the Rhodophyta (red algae). Thereare about 900 species of greenseaweed, 4000 red species and 1500brown species found in nature1. Thegreatest variety of red seaweeds isfound in subtropical and tropicalwaters, while brown seaweeds are morecommon in cooler, temperate waters.

Economic importance

Some 221 species of seaweed areutilized commercially. Of these, about145 species are used for food and 110species for phycocolloid production(eg. agar). Seaweed has been a staplefood in Japan and China for a very longtime. The green seaweedsEnteromorpha, Ulva, Caulerpa andCodium are utilized exclusively assource of food. These are often eatenas fresh salads or cooked as vegetablesalong with rice. Porphyra (Nori),Laminaria (Kombu) and Undaria(Wakame) are used for making fish andmeat dishes as well as soups andaccompaniments.

Agar-agar, agarose and carrageenanare commercially valuable substancesextracted from red seaweeds and findextensive use in many industries. Thegreatest use of agar is in associationwith food preparation and in thepharmaceutical industry as a laxative oras an outer cover of capsules. With theadvent of modern molecular biologyand genetic engineering, agar gumsproducing an ‘agarose’ factor are usedextensively in electrophoresis in mostlaboratories around the world.Carrageenans are generally employedfor their physical functions in gelation(include for example, foods such as icecream), viscous behavior, stabilization


Philippines accounts for nearly 80 % ofthe world’s total Eucheuma cottoniiproduction of 1,30,000 tons, roughly 35% of which is traded in dried form. Itsupply 14 % of the world’s total rawseaweed production and holds firstrank as producers of semi-refinedcarrageenan, contributing close to 60 %of the world market.

Seaweed resources of India

Seaweeds grow abundantly along theTamil Nadu and Gujarat coasts andaround Lakshadweep and Andamanand Nicobar islands. There are also richseaweed beds around Mumbai,Ratnagiri, Goa, Karwar, Varkala,Vizhinjam and Pulicat in Tamil Nadu andChilka in Orissa5. Out of approximately700 species of marine algae found inboth inter-tidal and deep water regionsof the Indian coast, nearly 60 speciesare commercially important. Agaryielding red seaweeds such asGelidiella acerosa and Gracilaria sp. arecollected throughout the year whilealgin yielding brown algae such asSargassum and Turbinaria arecollected seasonally from August toJanuary on Southern coast. A standingcrop of 16,000 tons of Sargassum andTurbinaria has been reported fromIndian waters6.

The surveys carried out by CentralSalt and Marine and Chemical ResearchInstitute (CSMCRI), Central MarineFisheries Research Institute (CMFRI)and other research organizations haverevealed vast seaweed resources alongthe coastal belts of South India. On theWest Coast, especially in the state ofGujarat, abundant seaweed resourcesare present on the intertidal andsubtidal regions7. These resourceshave great potential for thedevelopment of seaweed-basedindustries in India.

Seaweed industry in India

The seaweed industry in India is mainlya cottage industry and is based only onthe natural stock of agar-yielding redseaweeds, such as Gelidiella acerosaand Gracilaria edulis, and alginyielding brown seaweeds species suchas Sargassum and Tubineria6. Theproduction of total seaweeds in Indiain 2000 was approximately 600,000 tons(wet weight). India produces 110-132tons of dry agar annually utilizingabout 880-1100 tons of dryagarophytes. Annual algin productionis 360 to 540 tons from 3,600 to 5,400tons dry alginophytes.

Perhaps, the first large scalecommercial cultivation of seaweeds in

India has been embarked upon byPepsi Foods Ltd. (PFL) along a 10 kmstretch of the Palk Bay side towardsMandapam (Ramanathapuram Dist.) inTamil Nadu, with technical supportfrom Marine Algal Research Center,CSMCRI, Mandapam. They havestarted cultivating Eucheuma cottoniand Hypnea musciformis in an area of100 hectares through a contractfarming system in which seaweeds aregrown in individual plots of 0.25 ha (40m x 60 m). Each harvest cycle fromplanting to harvesting takes 45 dayswith an annual yield of 100 tons (wetweight) per hectare, which translatesinto 10 tons of dry seaweed or 2.5-3tons of carrageenan. The company hasplans to expand culture operations toover 5,000 to 10,000 ha in the nearfuture. Furthermore, many agar andalgin extracting industries have beenestablished in different places inmaritime states of Tamil Nadu, AndhraPradesh, Kerala, Karnataka and Gujaratthe seaweed industry is certainly onits way towards establishing itself wellin India.

Seaweed mariculture

Large-scale seaweed mariculture iscarried out only in Asia, where there isa high demand for seaweed productsand burgeoning populations to createmarket growth. Cultivation of seaweedsin Asia is a relatively low-technologybusiness in that the whole, attachedplants are placed in the sea and there isa high labor content in the operation.Except for the large kelp harvesters ofSouthern California and Baja Californiaor in Philippines and Taiwan Provinceof China, most seaweed are grown orharvested from wild stocks usingmanual techniques.

The demand from the phycocolloidindustry of India is great but thepresent production from naturalhabitats is very low and insufficient tocater to the needs of the local industry.This gap between the demand andsupply can be bridged throughmariculture practices for seaweeds bycultivating the useful species oncommercial scale. Continuous supply,improved yield and quality as well asconservation of natural seaweeds bedsare some of the important advantagesof seaweed mariculture.

Japan Kombu Laminaria Brown China Hai Dai Japan Nori / Amanori /

Hoshinori China Zicai Korea Kim

Porphyra Red

UK (Wales) Purple laver / Laver bread

Japan Wakame Undaria stipes Undaria pinnatifida

Brown

China Quindai cai

Scotland Dulse Ireland Dillisk

Rhodymenia palmata Palmaria palmata

Red

Iceland Sol Chondrus crispus Red Europe Irish Moss / Carraghean Asparogopsis taxiformis

Red Hawaii Limu kohu

Misc. sp. - Hawaii Limu

Table 1: Different edible seaweeds with their local names

Species Type Country Local name/product


Rope with seaweed fragments

Anchor cable

Synthetic floats Main rope

Stone

Figure 1: Single Rope Floating Raft culture technique

The main culture methods involveeither vegetative propagation usingfragments from mother plants or bydifferent kinds of spores such aszoospores, monospores, tetrasporesand carpospores. Kelps (brown algae)cannot be grown from fragments asthere is a high level of specializationand fragments of sporophytes do notregenerate whereas the agarophytecultivation can be done by vegetablepropagation starting from fragments.Fragments of adult plants, juvenileplants, sporelings or spores are seededonto ropes or other substrata and theplants grown to maturity in the sea.

Amongst the many culturetechniques, the Single Rope FloatingRaft (SRFR) technique developed byCSMCRI is suitable for culturingseaweeds in wide area and greaterdepth (fig. 1). A long polypropylenerope of 10 mm diameter is attached to 2wooden stakes with 2 synthetic fiberanchor cables and kept afloat withsynthetic floats. The length of thecable is twice the depth of the sea (3 to4 m). Each raft is kept afloat by meansof 25-30 floats. The cultivation rope (1m long x 6 m diameter polypropylene) ishung with the floating rope. A stone isattached to the lower end of thecultivation rope to keep it in a verticalposition. Generally 10 fragments ofGracilaria edulis are inserted on eachrope. The distance between two rafts iskept at 2 m. Floating raft technology

has been recommended to be used onthe Kerala coast for agarophytecultivation8. Certain areas in the Gulf ofKutch have been suggested as suitablefor deep-water seaweed cultivation7. Inaddition, CMFRI has developed andperfected techniques for culturingGelidiella acerosa, Gracilaria edulis,Hypnea musciformis andAcanthophora spicifera, and nowattempts are being made to findimproved techniques for propagationand large scale culture of othereconomically important seaweeds.

Problems and Prospects

The major problems in the seaweedindustry include overexploitationleading to a scarcity of raw material,poor quality raw material, laborshortages during the paddy harvestingand transplanting season, lack oftechnology to improve processedproduct quality, and a lack ofinformation on new and alternativesources of raw materials.

Despite the great number ofsheltered bays and lagoons suitable formariculture, no large-scale attempts togrow seaweed have been made in Indiaso far. Efforts are needed to increaseproduction through improvingharvesting techniques, removal ofcompeting species, creation of artificialhabitats and seeding of cleared areas.As the technology for reliable methods

for the cultivation of differentcommercially important seedstocks andtheir improvement has either alreadybeen developed or presently being inresearch, it needs to be disseminatedeffectively to the target community.Extensive surveys need to beconducted to identify suitable sites forlarge-scale seaweed culture.

There is great potential for theagarophyte cultivation because of itslow availability from the wild stock dueto over-exploitation. Many edibleseaweed species are available on theIndian coast; attempts should be madeto develop products suitable for theIndian palate and to popularize thesame amongst the public. With regardto pharmaceutical substances, heparinanalogues (heparinoids) that areinhibitory to thrombin activities havebeen reported from Chlorophyta ofIndian coasts9; this and many otherimportant types of seaweed areavailable on Indian coast that can beutilized for production of manyimportant pharmaceutical productsthrough extraction of bioactivecompounds.

Attention should also be giventowards developing hybrid specieswith superior growth and nutritionalcharacteristics, as the same has beenproved successful in countries likeJapan. Rather opting for high-volume-low-value seaweeds, culture of high-value seaweeds should be aimed for, aspart of integrated coastal and nationaldevelopment programmes10.

Seaweed polyculture in associationwith molluscs and fishes seems to havegood prospects to increase harvest andprofits. Pond and canal culture ofseaweeds (e.g. Gracilaria) in shrimpfarming areas can help to treat theeffluent water. The problem ofeutrophication of culture ponds due tooverfeeding and excreta released byfish/shrimp can be tackled by culturingseaweeds in such ponds.

Out of estimated around US $ 3billion global phycocolloid andbiochemical business, India’s share ismeager. We can surely grab a biggerpart in this lucrative business withsincere efforts towards large-scalecultivation of commercially importantspecies and processing. To facilitatethis, more technologicallysophisticated extraction plants witheasy access to markets and marketing


Shrimp harvestingtechnology on the south

west coast of BangladeshS. M. Nazmul Alam, Michael J. Phillips and C. K. Lin

The bottom of the ponds is generallyirregular.

The farming period starts fromFebruary to the end of November withmultiple stocking and harvestingmethods. The different categories ofshrimp farmers described above usealmost the same type of managementactivities for pond preparation andgrow out. However, the application rateof fertilizer, stocking density of postlarvae, and water exchange rates varyfrom farmer to farmer.

The average water depth in thepond is 0.6 meters. Generally the depthis reduced around 10-15 cm at two-week intervals. 10-30% of the pondvolume is exchanged during tidalregimes and farm outflows aredischarged directly to the commonflushing cum drainage canal.

The farms are usually rectangular orirregular with a large surface area. Theactual farm size is highly variable.Shrimp farms under individualownership are generally smaller in size(average 2.3 ha) than that of the farmowned by the farmers group (average4.6 ha). The largest farms are occupiedunder outside lessee (19.6 ha) rangingfrom 10.8 ha. - 36.4 ha. Yields ofPenaeus monodon are variable rangingfrom 109 kg/ha to 146 kg/ha.

Harvesting is generally carried outafter 90-120 days of extensive shrimpfarming. Harvest is usually done earlyin the morning and a number ofdifferent methods are used. Theharvesting techniques also vary amongfarm owners. The harvesting usuallytakes place during full and new moonof a lunar cycle. A cycle consists of 5-7days. The used water from the farm ispartially drained out through the canaland fresh tidal water introduced intothe farm. The shrimp become excitedand start moving towards the entrypoint of the tidal water as shrimp byhabit like to swim against the current.

Shrimp farming is an ancient traditionalpractice along the southwest coast ofBangladesh. This kind of farming is anatural rearing process in its simplestform. The main species grown are theblack tiger shrimp Penaeus monodonalong with other finfish as by-catch.

The ownership patterns of extensiveshrimp farming systems are complexand vary from area to area inBangladesh. The major categories ofshrimp farm ownership are:• Individual owner: The land in the

farm is owned and operated by oneperson. The landowner invests cashaccording to his capability andenjoys total returns from the farms.

• Farmers group: The land in the farmis owned by a number of personswho all pay an active role inoperating the farm. They contributeland and money and do the farmingjointly. They also share the returnson shrimp from the farmproportionate to their contributionof land, cash and physical labor.However during paddy cultivationeach farmer in the group cultivatepaddy singularly.

• Outsider lease: The land in the farmis leased out by owners to a personor persons living outside the Polderarea. The outsiders provide capital,and usually set up shrimp farmstaking most of the land from smalland medium landowners. Theyusually ally themselves withneighboring medium landowners bytaking their land and give them ashare in the farm operations andincome. This is done to gaininfluence over the land and controlover the local people.

Shrimp farms are located in the inter-tidal range. Farm design is highlydependent on the characteristics of thesite selected and there is no consistentdesign. However, most farms follow anopen system with no treatment ponds.

organizations need to be establishednearby cultivation areas to utilize theresources efficiently with greaterprofits.

Since it requires low inputs, andprovides good returns and can employmany people seaweed culture is a goodindustry for coastal communities. Theefforts in seaweed cultivation and itsutilization through product and processdevelopment could help in meeting thefood and nutritional security of Indianpopulation as well as augmenting valueof total fisheries export. Seaweed has avery important role to play towardsbetterment of coastal fishingcommunities and as a valuable foreignexchange earner. The need of thepresent hour is to train, encourage andpromote coastal fishermen populationat suitable sites, through combinedefforts of respective StateGovernments, research institutes,seaweed industry, Marine ProductsExport Development Authority andlocal NGOs, to adopt commerciallyviable large-scale culture technologies,and to provide them with goodmarketing facilities through properchannels.

References

1. Dawes C. J. (1981) Marine Botany. John Wiley &Sons, New York.

2. Chapman V. J. (1970) Seaweed and their uses. Secondedition, Methuen & Co. Ltd., London.

3. Stein J. R. and Borden C. A. (1984) Causative andbeneficial algae in human disease conditions: areview. Phycologia, 23:485-501.

4. FAO (2002) Status of world fisheries andaquaculture. Food and Agricultural Organization ofUnited Nations, Rome, Italy.

5. Kaliaperumal N. (1992) Seaweed culture. In:Handbook of Aquafarming.

6. Kaladharan P. and Kaliaperumal N. (1999) Theseaweed industry in India. Naga, the ICLARMQuarterly, 22(1): 11-14.

7. Dhargalkar V. K. and Deshmukhe G. V. (1996)Subtidal marine algae of the Dwaraka coast (Gujarat).Indian Journal of Marine Sciences 25(4): 297-301.

8. Reeta J. and Sally V. (2002) Cultivation of marine redalga Gracilaria edulis (Gigartinales, Rhodophyta)from spores. Indian Journal of Marine Sciences 31(1):75-77.

9. Shanmugam M., Mody K. H., Ramavat B. K., SaiKrishna Murthy A. and Siddhanta A. K. (2002)Screening of Coadiacean algae (Chlorophyta) of theIndian Coasts for blood anticoagulant activity.Indian Journal of Marine Sciences 31(1): 33-38.

10. Williams M. J. (1997) Aquaculture and sustainablefood industry in the developing world. In:Sustainable Aquaculture. J. E. Bardach (Editor),John Wiley & Sons, Inc., New York.


Earth made Gai mostly operated byindividual or group farm owners

Concrete made Gai by outside lessee

The following methods are inpractice for harvesting of farmedshrimp in the area.

Gai method

A very small portion of the farm isconverted into a rectangular shapedharvesting area. This area is preparedadjacent to the canal. The individualand farmer groups build the area withsoil dikes all around. One wooden gatelocally called tepata of varied size isplaced in the inner dike of the area tocontrol of the flow of water from bothsides. The outside lessees build thedikes and bottom with concretematerials to ease the harvestingprocess. Individual farmers place abamboo fence laterally a short distancefrom the canal to prevent the escape ofshrimp and fishes. Better off farmersoperating either as individuals or ingroups now use plastic pipes to makethe fence as it is more durable andlong-lasting. This fence is called mainpata. Another ‘V-shaped’ bamboo madefence is set up to a little distance fromthe main pata. This fence is called pustipata. The tail end of this fence is facedagainst the incoming water. This endhas small vertical opening to allowshrimp to enter into the vacant areafrom the farm. The area in betweenthese two fences is the catchment areaand the total harvesting area is locallycalled Gai.

Shrimp enter the catchment areathrough a narrow passage of the fence,and cannot go back to the rearing areaof the farm. When the inflow of thewater has become stationary shrimp arecaught with cast net. The outsidelessee sometimes drags the cast net, asthe bottom is smooth concrete. Lastly,the water of the catchment area istotally drained out and the last fewpieces of shrimp are caught manually.The system is repeated during a lunarcycle.

Trap method

Trapping is another way of harvestingshrimp. Some bamboo traps, locallycalled Aatol and measuring of varioussizes (standard 60cm x 75cm x 60cm) areplaced at 2.5-3metre intervals from theperiphery to inside the farm. Finemeshed net is attached to each of thetraps. These are set up in the deeper

area of the farm. During the flow of thetide the shrimp usually move towardsthe edge of the dike and happen toentry into the traps. The are checked atintervals, the shrimp removed and thetraps reset. This system continues untilthe end of each lunar period. The Aatolis also placed at the attachment of themain pata of the Gai. The large shrimpfarms, especially outside lessee usuallyset up the Aatol where shrimp areunable to move to the Gai because ofthe tide. All categories of shrimp farmerbelieve that the hatchery bred shrimpfry are not capable of moving to the Gaiagainst a strong current. So the farmowners put traps out at intervals toharvest the shrimp.

Net method

Cast nets are used for harvesting theshrimp when the farmer finds feweramounts of shrimp is caught in the Gaior in the trap. The farm owner engagessome cast net owners. The nettersstand close to each other and casttogether. Thus they move forwardcasting nets all over the farm andshrimp are harvested. This technique isparticularly used by large farm owners(outside lessees) at the end of season.

Market

A small size floor is constructed nearthe Gai and is called Chatan. This placeis used for washing, sorting and sellingof shrimp. A guardhouse made by nypaleaf is also constructed close to theGai. The harvested shrimp are kept indifferent kinds of bamboo crates/coops. The shrimp are washed withsaline water and placed in a heap atChatan to make ready for sale at thefarm gate. The Chatan is made ofconcrete by the outside lessees, butsmall individual and group farmersprepare the area with earth instead andplace a piece of polyethylene sheet onit during selling time. The buyer comesto the farm gate, bargains and settleson the price. Sometimes selling throughauction is takes place due to presenceof a number of buyers. The bid winneroccasionally shares the lot with otherfellow buyers who came to bid to keepsocial harmony. The head-on shrimpare then taken into the local depot foricing and are forwarded to theprocessing plant within shortest

possible time for beheading andonward dressing.

Acknowledgements

This article is a part of thesis researchwork performed through a studyattachment with the Asian Institute ofTechnology, Thailand. The authorsgratefully acknowledge the researchgrant supported by DANIDA.

References

Alam, S. M. N., 2002. Shrimp Based Farming Systems inSouth-western Coastal Zone of Bangladesh. Masterdegree Thesis. Asian Institute of Technology,Thailand. 102p.

Caritas, 1997. Ownership and participation in shrimpculture under Third Fisheries Project (Shrimpcomponent), 2-Outer Circular Road, Shantibagh,Dhaka, Bangladesh. 42p.

About the authorsS. M. Nazmul Alam has recently completed M. S. degree

on Integrated Tropical Coastal Zone Managementfrom Asian Institute of Technology (AIT), Thailand.E-mail: [email protected]: 169-WestAgargaon, Shere Bangla Nagar, Dhaka-1207,Bangladesh. Tel: 880 2 8117258.

Michael J. Phillips is an Environmental Specialist withNetwork of Aquaculture Centres in Asia-Pacific(NACA), Bangkok, Thailand.

C. K. Lin is an adjunct Professor in Asian Institute ofTechnology, Thailand.


Farmers as ScientistsThis is a series anchored by M.C. Nandeesha. It describes farmer-driven

innovations and experiences.

Dr M.C. Nandeesha is Head of theDepartment of Aquaculture, College ofFisheries, Central Agricultural UniversityTripura, India. Email [email protected]

The “Gher Revolution”Innovations in freshwater prawn farming by Bangladesh

farmers

countries and more than 400 delegatesattended the event. Mr. Michael Newtook part in this symposium anddelivered the key note address.Historically , a lot of significance wasattached to the participation andpresence of Michael New and inparticular for the constant efforts madeby him in stimulating timely debate onGFP and driving healthy growth of theindustry.

India produced a very small amountof fresh water prawns from the culturedenvironment about two decades ago.Ten years ago the College of Fisheriesat Kerala Agriculture Universityorganized the first symposium onfreshwater prawn farming in India. Ihad the opportunity of attending thatsymposium. Most people were not surehow the industry would expand furtheras many technical and social questionsremained unanswered. However, thelatest symposium organized by thesame College in August 2003 a decadelater clearly demonstrated that theirvision on the potential of this specieshas been right and the industry is likely

to further expand greatly. Today , withthe research and developmental effortsof many organizations and farmers inparticular, giant freshwater prawnfarming has grown into a majorindustry in the country contributing tomore than 30,000 tons of production.Over 34,000 ha of water bodies areunder the culture of this species. Landlocked states are perfecting thetechnique pf producing prawn seedusing artificially constituted sea water.As per the information presented in thesymposium, based on 2001 statistics,China is leading with a production of128,000 tonnes followed by Vietnam (28,000 t) , India ( 24,230 t) , Thailand(12,067) , Bangladesh (7000t) , Taiwan(6859 t) , Brazil, (5380 t) , etc. Theseproduction figures need to be viewedwith caution as the data collectionsystems for aquaculture production isyet in developing stage in manycountries. However, most importantly ,much of the production of GFP comesfrom small farmers . The species iscontributing immensely in povertyalleviation and ensuring most essentiallivelihood necessities of these smallfarmers. As it is time to learn from therepeated success of this speciesculture by small farmers, in this articlean effort is made to document the“Gher Revolution” accomplished bythe farmers of Bangladesh.

Cultivation of GFP in Ghers:Bangladesh farmers

innovation

Gher is a Bangla word used for thephysical construction made forgrowing freshwater prawns in animpounded environment. Theseconstructions, generally built in paddyfields, are used for growing both paddyand prawns / fish. The Ghers usuallyhave a large dike with canals and anarea dedicated for paddy cultivation

Giant Freshwater prawnproduction

Globally , the freshwater prawnindustry is growing at a rapid speedsurpassing all estimations andassumptions. Mr. Michael Neworganized the first dedicatedsymposium on Freshwater prawn morethan two decades ago in Bangkok incollaboration with the Department ofFisheries and brought out a specialpublication with selected papersentitled Giant Prawn Farming throughElsevier . That global eventconsolidated research anddevelopment directions for giantfreshwater prawn (GFP) farming. Thelatest revised publication of the manual“Farming Freshwater Prawns ( FAOTechnical paper 428) further indicatesthe growing importance received bythis group from farmers, researchersand development personnel. InAugust, 2003, in Kochi , in thesouthern part of India , an internationalsymposium on Freshwater prawns washeld with representatives from 15

Happy fish farmers display the harvest of giant prawn from Ghers. Periodic harvestinghelps farmers to access income regularly throughout the culture period


within the Gher. Generally , less than50% of the area is allocated for canaland rest of the area is used for paddycultivation. The latest productionfigures reported by various authorsfrom Bangladesh indicate that thecountry is already producing about12,000 tones of giant fresh water prawnfrom Ghers. This huge quantity isproduced by a large number of families(100,000) in an area of 30,000 ha usingthe types of Ghers described above.The farmers involved in the activity aregenerally very small farmers with landarea being less than 0.3 ha.

Necessity is the mother ofinvention

With high population density, farmersin Bangladesh have always had a needto innovate to increase productivityand income from the small area of landowned by them. Paddy is the widelycultivated cereal crop in the country.With large amounts of water loggedarea rice and fish became the staplediet of the people. With themodernization in agriculture resultingin heavy usage of fertilizers , pesticidesand high intensity cropping patterns,many fish species have beendisappearing from the environment . Inthe Southwestern part of Bangladesh,paddy cultivation was compoundedwith the problems of productivity andprofitability. To meet their livelihoodnecessities, farmers have been lookingfor alternative profitable crops. Theavailability of freshwater prawn post

larvae in the costal environmentencouraged some of the progressivefarmers to explore ways of culturingprawns in paddy fields. Their initialsuccess encouraged farmers toinnovate improved ways to grow bothpaddy and prawn together. Smallditches were converted in to canalswith more than a meter depth to holdwater during the dry season and thesecanals sometimes either covered all thefour sides of the paddy field or, basedon convenience, covered only someportion of the paddy field. As a generalprinciple less than 50 % of the areawas used for canals and rest of the areafor growing paddy. This activity,which started as a small venture inBagherhat district, has spread to

almost all parts of Bangladesh althoughstill most of the activity is concentratedin the Southwestern part of thecountry. The farming area is reported tobe growing at about 10% / year.Recognizing the vulnerability of smallfarmers in undertaking giant prawnfarming, and with a view to reducerisks and increase profitability , DFIDundertook a massive programme ofassisting 15,000 families involved inGher farming through CAREBangladesh . The project used theinnovative potentials of farmers andhelped them to recognize the capacityavailable within themselves and in thecommunity to solve various problemsencountered in Gher farming. Usingknowledge as the basis, strategicinterventions were made in the keyproblem areas.

Practices followed

Although farmers began experimentingon culture of prawns in paddy fields ,high price for prawns influencedfarmers to resort to stocking of onlyprawns and grow only one crop ofpaddy during the boro season. Theyadopted high stocking with more than20,000- 30,000 PL / ha. Ghers weregenerally stocked with post larvae byApril-May and fed heavily with snailmeat as feed. Fish were either stockedat very low density or not used at all.Dikes were either underused or unused.Usage of pesticides to both paddy andeven the vegetables cultivated addedadditional costs. Harvesting was done

A Gher with paddy crop

Another model of Gher with canal surrounding the paddy field


intermittently with most harvest beingcompleted by December. Small sizeprawns were left and allowed to growup to March- April and harvestedbefore stocking with fresh post larvae.These culture practices were not veryprofitable due to the heavy cost offeed. Small farmers with no experienceentered prawn farming often withcapital borrowed with an interest rateexceeding more than 100% / year. Asthe average productivity of prawns isless than 250 kg/ha, with high inputcost on snail meat as feed some farmerswere pushed into a debt trap. Thiscreated a social crisis in several areasand created an impression thataquaculture was adversely affectingthe livelihoods of people. Hence , theDFID project implemented by CAREmainly targeted farmers with less thantwo acre of land and sociallyvulnerable groups with an objective ofassisting them to adopt sustainablefarming practices and help them derivebenefits from the system.

Reaching the unreached

Most developmental projects aim attargeting one member in the family forimparting knowledge under theassumption that the impartedknowledge is shared with othermembers in the family and also to savecost on training two people. However,such exchange of information betweenthe sexes often does not take placebecause of the existing social practices. Several important parts of aquacultureactivities are often carried out bywomen such as feeding fish andgrowing vegetables. Hence, the projecttargeted at least one male and onefemale member from each family. Thetraining used a group training approachwith 20-30 farmers in an area beingformed into a group. Because of socialconstraints, male and female groupswere formed separately.

The groups met at a fixed time atleast twice a month for a limited periodof time that would allow them to focuscompletely on the learning session.Usually , these meetings did not lastmore than 2-3 hours at a time. Thegroups identified common problemsthat are confronted by most farmersand prioritized the issues that can betackled using the resources that areeasily available to them. The projectWomen attending a learning session in the project area

Men attending a learning session in the project area

Women generally take care of vegetable cultivation on dikes.


assumed no responsibility to providecredit support or organize credit ,except that the knowledge andtechnical support needed to addressthe agricultural problems encounteredare provided from the project. Eachfield trainer was responsible formanaging at least 5-6 groups and wasencouraged to provide follow upsupport to farmers through individualvisits to the farm.

Learning sessions

Farmers identified several problemsrelated to technical aspects of prawnfarming , vegetable and paddycultivations, social aspects arising dueto expanding ghers and income and adeclining natural resource baseparticularly in regard to snailpopulations. As most farmers havebeen focusing heavily on the prawncomponent of the system , neglectingthe opportunity that is available toraise income from mixed farming ofprawn and fish , efficient utilization ofpond dikes for vegetable cultivation,use of the central portion of the gherfor growing at least two crops of paddyand reducing feed input cost byefficient management of feed resourceswere identified as the strategic areaswherein intervention could bringperceptible changes in the cultivationpractices. Hence, learning sessionswere planned to address theseproblems by enriching farmersknowledge and helping them to set upobservation plots either in their ownfarm at little or no risk or making acollective observation with one or moreof the farmers in the group. Eachlearning session was centered aroundthe most felt necessity of the groupand on several occasions , farmersthemselves were asked to develop thesession contents with only supportfrom the project to provide them withthe technical information. Hence, theuse of group approach with creation ofatmosphere of trusting and respectingthe knowledge of each other helped ingetting the best from each farmer infinding solutions to the problemsencountered.

A tin shed based house is an indicator of the wealth status of family. A Gher farmer isfinishing the house built with income earned from Gher farming

Thatched houses indicate the poverty level, note the roof being replaced with tin sheets

Impact of learning sessions oninnovations

The Learning sessions began to makechanges in the culture practices offarmers with the increasing confidenceof farmers on the trainers andunderstanding project’s sincere effortsto resolve problems using localresources. Farmers began nursing postlarvae to juvenile stage in hapa orimpounded canal sites and reducedstocking density; they stocked fishspecies along with prawn and used itas one of the prime approaches toincrease income; the dikes of ponds

were used for growing vegetables ofdiverse varieties with growing seasonextending to almost all the years.Instead of taking one crop of paddyduring the boro season , farmers begantaking two crops in wet and dryseasons. Pesticide usage was reducedin both paddy and vegetables andseveral farmers stopped usingpesticides based on the lessons learntfrom the observations they set up.Most importantly , farmers beganlearning strategies on feedmanagement to avoid wastage of feedand reduce their dependence on snailmeat. Locally available feed ingredients


like various oil cakes , rice bran , wheatbran and dry fish powder wereprocessed and used for preparing feedsand the processed feed ingredientswere compressed in to pellets usingdifferent types pellet making devicesthat were locally manufactured . Asurvey revealed almost eighteendifferent types of pellet makinginstruments were invented locally byfarmers. As can be seen in the pictures,bamboo available locally was used tomanufacture simple pellet makingmachines following the principle ofpressure pump.

Reaching beyond the targetedgroups

Spreading the message across largesection of the community practicingGher farming called for new innovativeapproaches to be tried based on thelocal customs. The Bengal region beingrich in culture , folk songs and dramashave tremendous mass impact. Specialfolk songs and dramas appropriate tolocal traditions were explored coveringvarious aspects of Gher farming ,including poaching with an objective ofbringing visible changes in the culturepractices beyond the targeted group of15,000 families. Evaluation studiesconducted following such publicdemonstrations revealed that largepercentage of farmers changed some ofthe practices following the knowledge

gained from such publicdemonstrations.

Use of cooperative spirit andlocal knowledge

Gher farming has been reported tocause enormous damage to waterdrainage systems through improperplanning of ghers in the area. However,when the village level competitionswere organized with elders on how theirvillage was about 50 years ago andwhat they would like to see in thecoming years, many new ideas emergedfrom the elderly persons who areconsidered as knowledge banks by thevillagers. Those ideas were used tomake community level planningappropriate to each village. An eco-village concept was adopted with anobjective of making villages free frompesticide usage, provision of goodsanitary measures to avoid healthproblems and plantation of adequatenumbers of trees to build up thevegetation helped in buildingcommunity based movements based onlocal knowledge and resources.

Gender and social issues

With Gher farming expanding theimpact on women in particular becamemore conspicuous. As the learningsessions were organized separately forthe women and men , there were no

easy opportunities to discuss genderissues together . Hence , plans weremade to bring both men and womengroups together , identify key genderrelated issues confronted in the familyand set pathways to resolve suchissues. For example increasingworkload on women due to gherfarming is an issue that needscoordinated efforts in the family .Education and other equalopportunities for girls are issues thatalso need the coordinated efforts andunderstandings of parents. Apart fromdiscussing some of the general issuesof gender at the end of learningsessions , special gender days werecelebrated wherein both men andwomen groups met together discussedthe common gender issues and madeplans. Project assessment resultsdemonstrate that the position ofwomen in the family and status in thesociety improved enormously with theintroduction of Gher farming in thearea.

Exploring new method of creditsystem

As the existing credit systems did notsuit the needs of prawn farmers, newmethods of credit that suit the prawnfarming cycle with long repaymentperiod were encouraged to beexperimented by the partner NGOs.

Women display locally designed feedmaking machines. These are constructedfrom bamboo. The one on the right side ismore commonly used

Pata Mallick, a widow with two children has been able to improve her family economy byresorting to Gher farming. Her children dream to acquire a good education with theincome derived


These payment systems proved usefulboth to farmers as well as lendingagencies. As the borrowed capitalconstituted major cost factor in theproduction cycle, farmers wereencouraged to make group savings andlend money to the needy farmers withinthe group. This approach developedbased on the principle of self helpgroups gave raise to considerablesavings and lending opportunitieswithin group members.

Knowledge based approach

The project used the approach ofimparting knowledge to farmers andhelp them in solving the problems bythemselves by group learning andsharing approaches using theresources available or that can beaccessed easily based on theircapacity. Evaluation results indicatethat most of the farmers were able toachieve improvements in productionand were pleased with the knowledgebased approach used. In fact , withbuilding of confidence of farmers onthe project strategy and approach,even there was no easy way todistribute even research materialsfreely to members of the group. In suchcases, farmers made an agreement onthe strategy to adopted. Five years ofworking experience with 15,000 familieswithin the project area and severalmore families beyond the project areaindicate that poor farmers will derivebetter benefits through knowledge

based approaches that help them tooptimize the resource utility in the farmand derive best benefits fromaquaculture on a sustainable basis.

Conclusion

Pata Mallick is one of the farmers whoworked closely with the project andderived benefit of knowledge basedintervention. With a small Gher , shehas been able to improve her familysituation. She lost her husband due toa poisonous snake bite few years ago.With two children , she had to struggleto cover the family expenses. Today ,gher farming has given her the requiredincome and brought stability. Herdaughter who was born handicappedwith the loss of one fore hand desiresto be a teacher and help people like hermother in the area with no education tobecome literates. Her son, having seenthe death of father with snake bite andno doctor and medicine available in thearea, desires to become a doctor. Timeand social circumstances will decidewhether they will accomplish theirdreams. However, several indicatorssuggest that diversified Gher farminghas been most beneficial to farmers inreducing risk and increasing income.

The Project has increasedproductivity of prawns from Ghers andcurrently it ranges up to 500 kg/hadepending on the strategies adoptedwith most farmers deriving around 350kg/ha in 8-10 month culture period.With the improved prawn productivity ,

increased income from fish , vegetableand paddy , the system is reported tobe growing and in the majority of casesgiving returns that brings smiles andlittle comforts these families. As perthe information presented in the Kochimeeting , there is an additional supportset up under the banner of Shrimp sealof Quality Organisation that helpsfarmers with certification when theymeet the standards. This is likely tohelp farmers in deriving a better priceand also create positive outlook for theproduct.

The lessons from Bangladesh DFIDCARE project , wherein I had anopportunity to work and see thechanges clearly demonstrate that GFPfarming can be an effective tool forpoverty alleviation and improvementsin livelihoods of the family. Hearingagain from several of the participantsfrom Bangladesh in Kochi InternationalSymposium on Freshwater Prawnsinfluenced me to write again on GFP forthe second time during this yearthrough this column. However, toensure such a positive change, itshould be noted that project investedheavily in capacity and confidencebuilding of staff involved with theproject work . Over 150 field leveltrainers interacted with more than15,000 families over a period of fiveyears to bring such a change. Theseground level staff were supported withvarious technical and managerial staffthat helped in the effectiveimplementation of the program. If someof these successful approaches areadopted in our extension / developmentprograms, we should be able to seemore benefits of aquaculture in povertyalleviation.

Lastly, Bangladesh farmers continueto depend heavily on wild caught seedfor culture and there is a need toinitiate programs to increase qualityseed production from hatcheries . Withlarge number of families engaged incollecting wild seed, as a by-catchseveral other species are beingdestroyed. This is likely to havenegative impact on the environment.Government has already banned thecollection of seed from nature . Withthe establishment of hatcheries in theprivate sector , the scenario shouldchange soon in the best interest of theindustry.Prawn farming is spreading to various regions in Bangladesh wherein it is grown with

paddy commonly


The Grouper Section has taken on a new and broader name: It has becomethe Marine Finfish Section to take account of other species. This sectionis almost wholly based on the Marine Finfish Aquaculture Newsletter whichis prepared by Sih Yang Sim (Editor), Michael Phillips (NACA EnvironmentSpecialist) and Mike Rimmer (Principal Fisheries Biologist of theQueensland Department of Primary Industries). Visit www.enaca.org/grouperfor more information on the network or email [email protected].

Marine Finfish Section

Regional study of seafarming technologies, productiontrends and market opportunities

reported to be increasing, and as inother countries, there is rapidlyincreasing use of feed fish foraquaculture, although marine fishfarming makes up so far only a smallproportion of that used. The futureplanned increases in aquaculture,including a 200,000 tonne target formarine fish, will certainly beconstrained by finite sources of feedfish, suggesting an urgent need tostimulate more effective use of thesefish feed resources. The second studyis an FAO initiative for 5 countryreviews of trash fish use inaquaculture, with results expected in2004. For further information on theACIAR review, contact Geoff Allan [email protected] Funge-Smith can be contacted [email protected] forinformation on the FAO review. Theexperiences of the ACIAR project “FIS/97/73 Improved hatchery and grow-out

technology for grouper aquaculture inthe Asia-Pacific region” in replacementof feed fish in grouper diets are alsobeing summarized into a guidancedocument, that will be available in early2004.

Request for information onPlectropomus

As reported in a previous issue, someresearchers and commercial operatorsare reporting success with breeding ofPlectropomus species. A commercialresearch and development project inMyanmar is working on red coralgrouper (Plectropomus pessuliferus). Ifanyone has any information on thisspecies, the contact email [email protected]. Theeditors would also be interested to hearof other R&D experiences withPlectropomus species, please send togrouper@enaca,org and we will includethe your experiences in a futurenewsletter.

Aquaculture Compendium

The response from marine fish networkmembers to assist with the AquacultureCompendium was very good, and workhas now started on several marine fishreviews and species profiles. The website www.cabicompendium.org/ac/gives further information on theproject.

Live Reef Food Fish Trade BestPractice Standards Review Workshop:WAS Asia Pacific, 26 September 2003

The Live reef Live Reef Food FishTrade Best Practice Standards beingdeveloped by the Marine AquariumCouncil (MAC), with various partners,is progressing, and a review workshop

NACA has started a cooperation withthe Terre des Hommes Foundation-Italy(THF) project in Phanga Nga Bay,Southern Thailand entitled “Children ofthe Sea – Requalification of Small-scaleFisheries Micro-enterprises andEcosystem-based Innovation ofAquatic Production Systems for theSustainable Development of ThaiCoastal Communities”. Thecooperation involves simultaneousstudies of seafarming technology andmarkets in southern Thailand, Bangkoklive fish markets and trading networks,regional markets for seafarmingproducts and a status review ofregional seafarming productiontechnologies. The emphasis will be on

seafarming technologies andcommodities that may be important tosmall-scale fishing communities inSouthern Thailand, including ananalysis of options for integratedseafarming. The outcome from thestudies is expected to be of widerinterest to the network, particularly forpeople working with small-scale fishingcommunities where there is potentialfor seafarming. Further information onthe project will be made availablethrough a new web site and a reportexpected to be available in July 2004. Inthe meantime, further information canbe obtained from Paolo Montaldi orSandro Montaldi [email protected].

Fish Feed and Feeding

With marine fish farming growing inAsia, there is increasing need to lookfor better options to reduce the use ofwild fish resources to feed groupersand other carnivorous species, and atthe least make more efficient use ofexisting resources. Two reviews havebeen initiated in 2003, which whencompleted should provide usefuldirection for future development offeeds and feeding practices for marinefish in Asia. The first is a studycommissioned by ACIAR in Vietnam onso-called feed fish use (definition: feedfish includes all fish used in anunprocessed form as a feed ingredient,either solely or in combination withother ingredients such as rice bran, tofeed other animals). The study isshowing the importance of feed fish toVietnam, as the largest fishery in termsof both volume and value. Catches are


of the latest draft of the aquaculturestandards was organised by NACA inassociation with the WAS Asia PacificConference on 26 September. Themeeting involved aquaculturespecialists from Australia, Thailand,Vietnam, Malaysia and Indonesia, withgood attendance from Thai Departmentof Fisheries staff from all coastalresearch stations. The workshopparticipants discussed the draftaquaculture standards, and madesuggestions for the different levels ofdocumentation required to supportimplementation of the standards, aswell as raising issues of more generalconcerning practical implementation ofthe standards. Particular attention wasgiven to so-called “Level 2documentation” - Best practiceguidance and “Level 3 documentation”- Implementation manuals (or tool kits),and other guidance required to providepractical support to implement thestandards/best practice. A furtherworkshop was held in Hong Kong/Southern China in late 2003. For furtherinformation, please contact Peter Scott([email protected])

Pacific Islands: SMART Project toBring MAC Certification to 10Countries

The Sustainable Management of theAquarium Reef Trade (SMART) Projectis a two-year MAC initiative to ensurePacific communities involved incollecting marine ornamentals are partof a responsible trade that contributesto sustainable livelihoods and MACCertification. The SMART Project willassist communities in ecosystemmanagement plans, responsiblecollection of aquarium products andmarket linkages within the added-valuecontext of MAC Certification. Theproject will also seek to increase thenumber of MAC Accredited certifiers inthe region. The SMART Project willfocus on economically disadvantagedcoastal fishing communities in theCook Islands, Federated States ofMicronesia, Fiji, Kiribati, MarshallIslands, Palau, Samoa, SolomonIslands, Tonga and Vanuatu. TheSMART Project is supported by theEuropean Union. Project partnersinclude the Foundation of the Peoplesof the South Pacific (FSPI) and JustWorld Partners (a United

Kingdombased group and FSPImember). FSPI is a network of non-government organizations throughoutthe Pacific with metropolitan membersin the United States, United Kingdom,Australia and elsewhere. For moremarine aquarium council news, pleasevisit the MAC web site atwww.aquariumcouncil.org.

A Novel Zero Discharge IntensiveSeawater Recirculating System for theCulture of Marine Fish, by IlyaGelfand, Yoram Barak, Ziv Even-Chen,Eddie Cytryn, Jaap Van Rijn, MichaelD. Krom, and Amir Neori

Results are presented of a zero-discharge marine recirculating systemused for the culture of giltheadseabream Sparus aurata. Operation ofthe system without any discharge ofwater and sludge was enabled byrecirculation of effluent water throughtwo separate treatment loops, anaerobic trickling filter and apredominantly anoxic sedimentationbasin, followed by a fluidized bedreactor. The fish basin was stocked forthe first 6 months with red tilapiaOreochromis niloticus x O. aureus atan initial density of 16 kg/m3. Duringthis period salinity was raised from 0 to20 ppt. Then, gilthead seabream,stocked at an initial density of 21 kg/m3, replaced tilapia at day 167 and werecultured for an additional 225 d. Nonsteady-state inorganic nitrogentransformations occurred as a result ofthese salinity changes. After day 210,the system operated at all times withthose water quality parametersconsidered critical for successfuloperation of mariculture systems,within acceptable limits. Thus ammonia,nitrite, and nitrate concentrations didnot exceed 1.0-mg total ammonia-N/L,0.5-mg NO2-N/L and 50-mg NO3-N/L,respectively. Sulfide levels in the fishbasin were below detection limits andoxygen > 6 mg/L after the oxygengenerator was added at day 315.Ammonia, produced in the fish basinand to a lesser extent in thesedimentation basin, was converted tonitrate in the aerobic trickling filter.Nitrate removal took place in thesedimentation basin and to a lesserextent in the fluidized bed reactor.Sludge, remaining in the sedimentationbasin at the end of the experimental

period, accounted for 9.2% of the totalfeed dry matter addition to the system.The system was disease-free for theentire year and fish at harvest were ofgood quality. Water consumption forproduction of 1 kg of tilapia was 93 Land 214 L for production of 1 kg ofgilthead seabream. Additional growthperformance data of gilthead seabreamcultured in a similar but larger systemare presented. During 164 d ofoperation of the latter system, maximumstocking densities reached 50 kg/m3and fish biomass production was 27.7kg/m3. Relatively poor fish survivaland growth resulted from occasionaltechnical failures of this pilot system.The full article is available from Journalof the World Aquaculture Society, Vol.34, No. 3, September 2003. For furtherinformation contact Department ofAnimal Science, Faculty ofAgricultural, Food and EnvironmentalQuality Sciences, The HebrewUniversity of Jerusalem, Rehovot76100, Israel.

News from Vietnam

Results released by World ResourcesInstitute in 2002 indicated thatVietnam’s coral reefs are among themost threatened in the region.Destructive fishing practices, such aspoison and blast fishing threaten asmuch as 85 percent of Vietnam’s reefswhile overfishing threatens more than60 percent of Vietnam’s reefs (Reefs atRisk Southeast Asia, 2002). In responseto such problems, the DanishInternational Development Agency(DANIDA) will assist $ 2.7 million tohelp Vietnam implement the project tosupport marine reserve area networkacross the country, according to anagreement signed in Hanoi onDecember 19, 2003. Fifteen marinereserve areas nationwide are selectedfor the 2003-06 network supportproject, which comprises two sub-projects. The first will be implementedin Hanoi with the aim of establishing aconsistent system of marine reserveareas and creating a legal framework forthe management of those areas. Thesecond, which will be carried out incentral Quang Nam province, willsupport the management of the Cu LaoCham reserve. The network will helpbalance marine ecosystems, protect seabiodiversity, regulate environment and


develop sustainable economy, as wellas eco-tourism. Vietnam is consideredone of the world’s most diversifiedmarine-biological centers. Some furtherbackground on reefs in Vietnam can befound at www.reefcheck.org/newsletter8/newsletter8.htm

Weekly Average Wholesales LiveMarine Fish Prices in Hong Kong

The weekly average wholesales livemarine fish prices in Hong Kong’sAberdeen Wholesales Fish Market isavailable on www.enaca.org/Grouper/FishPrices/FishPricesIndex.htm. Theprices are in US$, converted from HK$to US$ is at 1 HK$ = US$ 0.1282obtained from the Fish MarketingOrganisation (FMO). Furtherinformation can be found on the FMOwebsite.

Live Marine Fish Prices at theHuangsha Seafood WholesalesMarket, Guangzhou, China – 29-12-2003

NACA staff made a visit to the largestlive marine food fish market in China –the Huangsha Live SeafoodWholesales Market – at the end ofDecember 2003. The market sells a widerange of groupers and other coral reeffish from all over the Asia-Pacificregion. Information on wholesale pricesduring December are available (Chinesecurrency-Yuan, converted to US Dollarwith conversion rate of US$1 to Yen is8.2) at www.enaca.org/Grouper/FishPrices/FishPrices-China-29- Dec-03.htm.

Study Program on Marine FinfishAquaculture and Markets in SouthernChina and Hong Kong, July 2004

To provide further insight into marinefish farming and markets in southernChina and Hong Kong, NACA willorganized a study program toGuangzhou and Hong Kong, China inJuly 2004. The study program isorganized by NACA in cooperationwith the Guangdong Dayawan FisheryDevelopment Center (Department ofMarine & Aquatic Products, China),Guangdong Provincial Bureau of Oceanand Fisheries, Guangdong FisheriesSociety, and the Agriculture, Fisheriesand Conservation Department (AFCD)

of Hong Kong. More information onthis study program will be provided onthe marine fish network website in lateJanuary 2004 and interested partiesplease can contact Mr. Sih- Yang Sim([email protected]) for furtherinformation.

Improving Access to MarketInformation

In 2004, NACA intends to increasecoverage of market prices for marinefish in Asia, for both cultured andcapture fish, through a regular e-news.Key informants and informationsources are being identified in differentexport countries and key markets in theAsia-Pacific region. If you areinterested to get involved in thisinitiative, and to share information onmarine fish markets and prices, pleasecontact [email protected] for furtherinformation.

The International Seafood Trade:Supporting Sustainable LivelihoodsAmong Poor Aquatic Resource Usersin Asia

The international seafood trade hassignificant implications for manymillions of poor fishers and farmers indeveloping countries, most recentlyhighlighted by the World Fish Centerreport (Outlook for Fish to 2020:Meeting Global Demand). Global tradein fisheries products is a multi-billiondollar trade with developing countriesin Asia as major stakeholders.Projections are that developingcountries will become even moresignificant suppliers to global seafoodtrade in the future. Yet, the linksbetween such trade, poverty alleviationand livelihoods of poor aquaticresource users are poorly documented,and ways in which the seafood tradecan be oriented towards supportingpoverty reduction goals are poorlyunderstood. The implications of movestowards certification, stricterimposition of sanitary andphytosanitary standards and othertrade measures are potentiallysignificant for producing countries inAsia, probably impacting on thepoorest producers. A new projectentitled “The International SeafoodTrade: supporting sustainablelivelihoods among poor aquatic

resource users in Asia” is beingimplemented with support from theEuropean Community’s PovertyReduction Effectiveness Programme(EC-PREP) (a programme of researchsupported by the UK Department forInternational Development (DFID) toenhance the poverty impact of theEuropean Community’s developmentassistance and contribute to achievingthe International Development Targetof halving the number of people livingin extreme poverty by 2015). Theproject focuses specifically on exportsfrom Asia to the EU of shrimp and coralreef associated fish, principally marineornamentals, with case studies beingconducted in Vietnam, the Philippinesand Indonesia. Poseidon AquaticResource Management Ltd, theNetwork of Aquaculture Centres inAsia-Pacific (NACA), and the Supportto Regional Aquatic ResourcesManagement (STREAM) Initiative arecollaborating to implement the project.The project started with an initialreview in October 2003, and will rununtil to March 2005. Case study fieldwork will be conducted in Vietnam,Indonesia and the Philippines during2004, and then early in 2005 a finalreport with recommendations aboutpro-poor trade mechanisms will beprepared. Case studies on the marineornamentals trade should generatefurther understanding of the socialimplications of the trade, and possiblemechanisms to improve social benefits.A web site (linked to www.enaca.org)will be available to provide backgroundinformation on the project, and reports,from January 2004. The project buildson some of the experiences of theconsortium program on shrimp farmingand the environment (www.enaca.org/shrimp/) and APEC supported studiesof coastal livelihoods and coral reeffish aquaculture(www.streaminitiative.org).

Fish health news

As grouper and marine fish farmingstarts to expand in the region, there isincreasing concern about the spread ofserious aquatic animal pathogens.Already, there are reports of VNN andiridovirus being spread around theregion due to infected juveniles,causing significant losses on grow outfarms, and unknown effects on wild


stocks. Clearly, better management ofhatcheries and nurseries will beessential to reduce risks. In responseto such problems, the healthmanagement components of upcomingNACA courses are being strengthenedto emphasise better health managementin hatcheries and nurseries. A specialworkshop “Management ofenvironmental and health risks inmarine fish farming” is being plannedby NACA in late 2004 to develop somepractical guidance on managing ofsuch risks in hatcheries, nurseries andgrow-out farms.

Regional Training Course on GrouperHatchery Production 2004, Bali,Indonesia

The Asia-Pacific Marine FinfishAquaculture Network and itscooperating partners are planning forthe 3rd training course in 2004, thetentative schedule will be from March24-April 13. As the training course isonly taking limited number ofparticipants therefore it is important forthose who are interested to contact Mr.Sih-Yang Sim ([email protected]) toregister their interest and secure aplace in the training course. Thetraining course reports for 2002 and2003 are available from the NACAwebsite http://www.enaca.org.

Update on 2003 Training CourseParticipants

Dr. Trevor Anderson from GFBFisheries Ltd, Australia successfullyproduced some 20,000 Cromileptesaltivelis fingerlings in November 2003,with success also extended to E.coioides in his hatchery. Mr. Sufian B.Mustafa from the Marine FinfishProduction and Research Centre,Malaysia reported some success inspawning (Epinephelus species) afterimplementing pellet LHRH hormoneimplantation for broodstock. However,he reports larviculture problems,constrained by lack of S and SS-rotifer.Dr. K. Kailasam from the CentralInstitute of Brackishwater Aquaculture,India has seen improvement in grouper(Epinephelus coioides) breeding withsuccessful female fish spawned andfertilized by stripping method. Butlarvae did not survive beyond day 7.

national R and D institutions andinvites experts from other countries toprovide technical advice on a range ofissues including taxonomy andprocessing. Sri Lanka’s OrnamentalFish Producers Association works withnational technical and economicagencies and also engagesprofessionals and scientists, andfosters relationships with similarassociations in other countries. TheVietnamese fishery society – a vastwell-organized and powerful multi-stakeholder entity - includes in itsagenda building links and collaboratingwith national, regional andinternational organizations and otherNGOs to share experiences andinformation. Its biennial fisheryexhibition and technical conferencebrings in the participation of policymakers, scientists, technicians, farmers,input supply companies and technicaladvisers.

Included in the survey are thevillage farmers associations in EasternIndia (where STREAM and otherinternational agencies have beenoperating). The village associationshave realized that maintainingrelationships with the NGOs and stateand federal government agencies, andcontinuing their participation incommunity development activities cansustain the build up of their capacities.A recent move is to provide support fornetworking the various villageassociations to facilitate exchange ofinformation among them. Networkingbuilds up numbers. More importantly itbroadens the scope of theassociations’ influence through theiralliance fostered by networking.

Holding on to members and stayingfinancially stable are, for obviousreasons, the foremost organizationalconcerns of farmers associations indeveloping countries. Other than beingable to serve members’ needs, beingable to sell their produce at a profit isstill their best bet to staying viable,relevant and cohesive. The nationalassociations based on a single exportcommodity (almost all producersassociations are organized around asingle commodity) are dependent onthe market and, on top of coping withrisks posed by vagaries of nature and

markets, must comply with anincreasing number and stringency of“market requirements.” They haveshown that they are willing to complywith requirements - including thosethat ask them to be environmentallyresponsible, to assure that food safetyand quality are of a certain standard –as well as to work with government andother sectors on legislation, policies,and standards, and to promote andapply codes of practices and conductamong their members.

Pragmatically, they know thatenvironmentally sensitive and sociallyresponsible farming makes goodbusiness sense. However, to the smallfarmers, or even large but unorganizedfarmers, some elements of the “marketrequirements” can be a threat to theirstaying in business. This is a strongreason to organize to attain economy ofscale, and more importantly, to attain adegree of authority to be able tonegotiate from a position of strength.Being able to negotiate effectively - forfavorable prices and terms for theirproduct and for input supplies andequipment, for better allocation of oraccess to land, water and creditresources to the industry, for favorabletax structures and other incentives, foraccess to technology, for improvementof the marketing infrastructure andsystem, for fairer trade regimes, etc – isprobably the best way farmers’organizations can serve their members.

While maintaining viability is aprimordial concern, the associationshould have the ability to work withgovernment and other sectors ofsociety to shape policies and researchand development agenda, preciselydefine its needs and work with othersto meet those needs, bringprofessional and scientific advice intothe discussions and decisionprocesses (as the Federation ofEuropean Aquaculturists or FEAP doeswith great effectiveness), and engagein mutually beneficial alliances.

It is clear that to develop thepotentials of farmers organizations forsustainable development, it would bebest to provide them the environmentand motivations to attain a status ofauthoritativeness.

Notes from the Publisher



CD: APAARI Success Stories

The Asia-Pacific Association ofAgricultural Research Institutions(APAARI) have published a collectionof 17 success stories on thedevelopment of new agriculturalproducts, three of which areaquaculture related: Tilapia farming inthe Philippines, Bivalve Mariculture inIndia, and Farming of Red Seaweeds inthe Philippines.

System requirements: AcrobatReader. Available from the APAARISecretariat, FAO Regional Office forAsia & the Pacific, Maliwan Mansion,Phra Atit Road, Bangkok 10200,THAILAND, Tel.: (662) 281-7844, Fax:(662) 280-0445.

Field Guide to Australian Sharks andRays

A small user-friendly guidebook toabout 100 species of shark, ray andchimerids. It has a user-friendly formatwith pictorial keys to families and fullcolour photographs annotated with keyfeatures for identification. Species arearranged according to their broaddistribution – pelagic, northerndemersal, southern demersal and thereis also an interesting section on ‘rarelycaught’ species.

Each species has a short descriptionoutlining key features that can be usedto distinguish it from its near relatives.The main text also provides fishery andconservation information and remarksof general interest such as size. Adistribution map is provided along withan indication of the main fishing gear/method of capture. The guide waswritten by some of Australia’s leadingtaxonomic experts including R.K. Daley,J.D. Stevens, P.R. Last and G.K.Yearsley. Published by the CSIRODivision of Marine Research, theFisheries Research and DevelopmentCorporation and the AustralianFisheries Management Authority. 84pages.

Price: AUD$ 24.95 plus internationalfreight. Available from CSIROPublishing, PO Box 1139, collingwood,VIC 3066, Australia. Fax +61 (3) 96627555, email [email protected],www.publish.csiro.au.

Conclusion: Recommended as aportable general field guide. However,those seeking a comprehensivereference should try to get a copy ofthe 1994 publication Sharks and Raysof Australia (also by P.R. Last and J.D.Stevens) which unfortunately is nowout of print.

Aquaculture Pond Bottom Soil QualityManagement

Written by Claude E. Boyd, C.W. Woodsand Taworn Thunjai, 2002, 41pp.

This is a small and practical manualthat will be popular with anyoneworking on pond maintenance andrepair. It has three sections. The firstsection, pond soils, provides a shortreview of soil properties and theirinteraction with pond water. Thesecond, pond soil treatments, providesgeneral guidelines for carrying outvarious remedial measures includingliming, drying, tilling, sedimentremoval, fertilization, bottom raking,disinfection and probiotics. , and iii)soil analyses provides simpletechniques for assessing soilcondition.

The nice thing about this book isthat it is written with practicalapplications in mind – the subjects andtechniques described – including thesoil analyses – are things you can doon the farm. This is the book that youwill be flicking through while standingin the bottom of your dried-out pond !

Available from: Pond Dynamics/Aquacutlure Collaborative ResearchSupport Program, Oregon StateUniversity, Corvallis, Oregon 97331-1641, Tel +1 541 737 6416, Fax +1 5413447, www.pdacrsp.orst.edu

Conclusion: Recommended as agood pocket guide/ready reference topond soil management for techniciansand farm managers. For acomprehensive reference book nothingbeats Boyd’s earlier book WaterQuality in Ponds for Aquaculture(1990) but you won’t be carrying thatone around in your pocket.

Nutrient Requirements and Feeding ofFinfish for Aquaculture

C.D. Webster and C.E. Lim (eds.)418pp.

This is a ‘milestone’ publication, abook that takes a detailed snapshot ofthe current state of knowledge in afield. It summarises the current state ofknowledge in the nutritional


requirements of about 30 groups ofimportant aquaculture species from allover the world.

Each species is dealt with in anindividual chapter written by anutritionist who is an acknowledgedexpert. Sections include i) introductionto basic biology and commercialimportance, ii) nutrient requirements(protein and amino acids; energy; lipidand fatty acids; carbohydrates;vitamins and minerals), iii) formulationof practical diets iv) feeding practicesand v) a detailed reference list.Additional information is provided forsome species – for example the gilt-head sea bream Sparus aurata includessome nice sub-sections on the nutrientrequirements of different life stages (ie.larval fish, juveniles and broodstock),and the Atlantic salmon section alsocovers caratenoid pigments. Overall,the quality and presentation of theinformation is very high. The authorshave gone to considerable lengths toreview and summarise the literature.

It’s nice to see good coverage of theAsian region in such a volume. Asianspecies include the Asian sea bass(Lates calcarifer), Red sea bream(Pagrus major), Japanese flounder(Paralichthys olivaceus), yellowtail(Seriola quinqueradiata), milkfish(Chanos chanos), common carp(Cyprinus carpio), Indian major carps,tilapia, freshwater eels (Anguilla spp.),silver perch (Bidyanus bidyanus),snakehead (Chanos spp.) andPangasius catfish. The book alsocovers major European and Americanspecies.

Cost: US$140 + freight. Availablefrom: CABI publishing, CABInternational, Nosworthy Way,Wallingford, Oxon OX10 8DE, UK. Tel+44(0)1491 832111, Fax +44(0)1491829292, email [email protected],www.cabi-publishing.org.

Conclusion: Highly recommended,a very detailed resource. However, youmay wish to check that it covers yourspecies of interest before you purchasesince most of the information isspecies-specific.

Highland Fisheries & AquaticResource Management

K.K. Vass, H.S. Raina (Eds.) 2002.363pp.

Highland development is becominga priority in many countries as theseareas are not keeping pace withdevelopment in lowlands, due to moredifficult climatic, topographical andresource constraints. In particular,highland fisheries essential to thelivelihoods of many communities havenot received the attention theydeserve. This book attempts to addresssome of these issues with a collectionof 31 scientific reviews. The firstsection provides an overview of thestatus of highland fisheries in India’shighland/coldwater fisheries. The bookmoves on to address human resourcedevelopment in capture fisheries, withadditional sections on aquaculture andbiology (mostly concerning mahseerand trout), and conservation andmanagement in coldwater fisheries.There is an interesting papersummarizing internet application infisheries, which summarizes many ofthe websites and resources availableon the internet.

Available from the Director, NRC onColdwater Fisheries, Bhimtal 263136(Nainital), Uttaranchal, India.

Conclusion: A useful referencebook for hill fishery scientists,planners, policy makers, farmers andentrepreneurs alike.

Textbook of Fish ProcessingTechnology

K. Gopakumar (Ed.), 491pp.Internationally fish is traded mostly

in frozen form. New species and value-added fishery products are findingniches as the international trade

expands. Fish processing technologyhas become one of the most developedbrnaches of food processing science.

In India a number of agricultural andconventional universities have startedprogrammes at the graduate and post-graduate levels. However, until nowthere has been no textbook orcomprehensive reference available onthe subject. This book provides adetailed overview of fish processingtechnology. Coverage includes:Biochemical composition of fish; postmortem changes and qualityassessment; chilling (both direct andindirect); fish freezing technology;bacteriology of fish and shellfish;proteins and lipids of marine productsand their changes during processing;irradiation; fundamentals of drying

Continued on page 46...


Aquaculture Compendium –Case Study Component

Knowledge will be less for academicsand researchers in their “ivory tower”and more for development workers andfarmers at “grass root” level.

Although case study coverage willbe broad, emphasis is to be given topoverty-focussed, field based ruralaquaculture. Two countries are beingused as pilots to devise and test anapproach for a practially orientedknowledge base for aquaculture :Bangladesh and Vietnam. Thesecountries have been chosen becausefish plays an important role in theirnational economies yet there is still ahuge unfulfilled need for aquacultureknowledge by practitioners as well aspotential new entrant farmers. It isrecognized that the need for knowledgeis demand driven and case studies arebeing developed through aparticipatory approach to synthesizeand integrate existing knowledgerelating to aquaculture into theAquaculture Compendium.

Case studies are being identifiedand draft material produced in-countryin Bangladesh (facilitated by IoA /SUFER) and in Vietnam (facilitated byAIT) by individuals from thosecountries. The draft material will beedited by myself as Editor and AsiaRegional Specialist for CABI beforeverification of content by specialists.It will then be passed to CABI forincorporation into the Compendiumbut, before publishing in theCompendium, it will be field tested tosee if it meets the needs of intendedbeneficiaries. Feed-back from likelyend users will be used to modify casestudy materials before release of thefirst version of the AquacultureCompendium. The farmer or produceris the major ultimate target but in most

cases will be reached through localinstitutions. Examples are government,NGO and private sector extension andinformation providers, universities andvocational schools, and research anddevelopment projects.

Case studies will cover a range ofsystems in the two pilot countries :production systems, both seed andgrowout in inland and coastalaquaculture; integrated systems; inputsupply, marketing, trade andconsumption; and institutional systemsand governance. They will also cover aspectrum of issues or key topics suchas poverty alleviation, trash fish andfish and fish meal, and internationaltrade. An example of the latter are theproblems experienced by Vietnam inmarketing catfish in the United States.

There are potentially 100s if not1000s of case studies globally. About100 were identified in a BangladeshCountry Focus workshop held inDhaka on 12 and 13 November 2003. Asimilar number is expected from theVietnam Country Focus workshopscheduled for 13 and 14 January 2004 atthe University of Fisheries, Nha Trang.As there is a vast amount of existingmaterial, the intention is to usepublished / printed material as much aspossible to minimize rewriting andediting and to increase coverage.Besides the Bangladesh and Vietnampilot countries, case studies will be

An important event to facilitate thedevelopment of aquaculture in general,but especially rural aquaculture, will bethe publication of a new AquacultureCompendium. The Compendium will bean electronic multimedia encyclopaediaknowledge base which will serve as aversatile reference and problem–solving/opportunity-seeking resource.It is currently being developed byCABI Publishing, a division of CABInternational, one of the world’sleading applied life science publishersin association with the Asian Instituteof Technology (AIT), the Institute ofAquaculture, University of Stirling(IoA), the Network of AquacultureCentres in Asia-Pacific (NACA) and theWorld Aquaculture Society (WAS).The Aquaculture Compendium is taking2 years to develop, involvingcontributions from experts around theworld, and will be published in 2005.

The Aquaculture Compendium willbe the fourth one that CABI hasproduced, the others being CropProtection (1999), Forestry (2000) andAnimal Health and Production (2002).There will be another on Coffee, andthe feasibility of others on InvasiveSpecies, Plant Genetic Resources, andTropical Fruits in future is beingexplored.

A new feature for the CompendiumProgramme will be case studies i.e.,specific examples from real worldpractice. Case studies will thus linktheory and practice. They will be apotential learning tool as they willcover farmer practice, successes aswell as failures in research anddevelopment, and issues inaquaculture. The AquacultureCompendium is pioneering the creationof knowledge and its dissemination. ...Continued on page 46

Peter Edwards is a consultant and parttime Asian Regional Coordinator for CABIPublishing. Previously he was Professorof Aquaculture at the Asian Institute ofTechnology where he founded theaquaculture program. He has nearly 30years of experience in education andresearch relating to small-scale inlandaquaculture based also on extensivetravel throughout the region.


Rice-Fish Culture in ChinaFang Xiuzhen

Freshwater Fisheries Research Centre, Wuxi, Jiangsu 214081, China

Fish culture in paddy field was anancient farming practice found inseveral rice-growing areas, such asSichuan and Guizhou Provinces, inSouth and Southwest China. It can bedated back to nearly twenty centuriesago. In traditional rice-fish culturepractice, rice cultivation was the mainactivity of farmers, while some fishseeds were stocked in paddy fields andlooked after extensively, merely for thepurpose of having additional animalprotein food for householdconsumption by farmers. From the1950’s to late 1970’s, this once commonpractice faded out considerably as aresult of introduction of plannedeconomy run under rural communesand later the increase in use ofchemical fertilizers and pesticides.When economic reform was started in1978 and farmers began again to decideagain what they could do the best withtheir land for their families, somefarmers chose to resume fish culture intheir paddy fields just as theirancestors had done.

past. Eventually, rice-fish cultureemerged as an important rural farmingsystem by the early 1990’s. Its role inalleviating rural poverty and improvingthe rural economy, especially in remoteprovinces and regions, was widelyrecognized.

In the 1990’s, rice-fish farmingenjoyed a rapid expansion in thenumber of new entries and total area ofrice-fish production area in the country.The farming system has extended frompluvial and warm provinces in South,Southeast, Central and East China tothe Northeast and Northwest China,including several economically lessdeveloped regions, such as XinjiangUrgur Autonomous Region, InnerMongolia and Gansu Province. Duringthe course, it evolved from traditionalfamily-scale extensive operationstowards medium-to-large scale or evencommercial scale operations in selectedprovinces. The rapid expansion of rice-fish farming was the immediate result ofthe growing interest and enthusiasmamong farmers in the rice-growingareas, coupled with the continuouscollective supporting efforts from thepublic sector such as provision ofrelevant extension and advisory

services to farmers, application ofpolicy incentives and betteraccessibility to loans for renovation ofconventional paddy field to suit fishculture and four nation-wide rice-fishculture field seminars.

By 1999, the area of rice-fish farmingin China reached 1,464,094 ha, anincrease by 71.6% from 853,000 ha in1994. The rice-fish farming area furtherexpanded to 1,528,027 ha 2001. Foodfish production from paddy fieldincreased from 206,900 tons in 1994 by214% to 649,996 tons in 1999. The foodfish production from rice fieldincreased to 849,055 tons in 2001. Theincrease in food fish production frompaddy was not at the cost of rice yieldreduction. Instead, rice yield from therice-fish farming attained an averageincrease of 225 kg per ha over theperiod 1994-1999.

Farming systems

The technological advances borrowedfrom pond aquaculture and thechanges in market demand have lead tothe changes in the rice-fish farmingpractices including the species usedand the scale of operation. To maximize

Development in the pasttwo decades

In 1983, a national field seminar on rice-fish culture was conducted for the firsttime. As a result, the socio-economicand ecological benefit of rice-fishculture started to draw the increasingattention of farmers and various publicsectors. A series of follow-up actionsrecommended during the seminar leadto the gradual spread of rice-fishculture from its traditional homes toareas where it was not practiced in the

Sumps provide a refuge for fish and a reservoir during the dry season


the use of natural productivity in thepaddy field space for the optimaleconomic returns, various rice-fishculture models with variations ofintegration with crop and animalspecies were developed through fieldtrials by farmers in different parts of thecountry according to the localconditions and available resources.

Several newly developed rice-fishculture models with desirable economicreturn became popular among farmers,and the examples include the culture ofhigh-value fish species with rice inChongqing suburb, giant freshwaterprawn culture with rice in JiangsuProvince, native freshwater shrimpculture with rice in Shanghai suburband Chinese mitten-handed crab inLiaoning Province. With intensifiedmanagement and increased input,including artificial feeding, rice farmerscould gain an average annual net profitof USD 1,813 per ha from the animalsthey raise in their paddy with thesenew models.

Paddy field renovation

At present, most paddy fields used forrice-fish culture have been renovatedto varying degrees in favor of fishgrowth. The renovation usuallyincludes the excavation of ditches andsumps as shelter for fish and buildingof higher and wider dikes. About 10-20% of the total area is converted forthese purposes. Paddy fields with suchrenovations on average could produce

at least 7,500 kg of rice and 750 kg offish per ha without artificial feeding.The fish yield can be significantlyincreased as farmers develop betterskills in handling their fish and increasetheir inputs, such as fish seeds andfeed, into the system.

Fish species used in rice-fishculture

In the past two decades, the fishspecies employed in rice-fish culture asa whole have changed from simplespecies combination, such as Chinesecarps and common carp, into a multi-species combination. Both monocultureand polyculture are adopted.Nowadays, a great diversity of aquaticanimal species is found in the rice-fishculture systems, adapting to the widerange of farming systems and marketenvironment in different parts of thecountry. Apart from the traditionalfinfish species, crustaceans,amphibians, mollusk and reptilesbecame common in rice-fish culture.The general trend is shifting from lowvalue carp dominated species towardsspecies that could fetch higher marketprice. Currently, the popular species forrice-fish culture in China are Chinesecarps, tilapia, swamp eel (Monopterusalbus), eel (Anguilla japonica), giantfreshwater prawn (Macrobrachiumrosenbergii), native freshwater shrimp(M. nipponensis), Chinese mitten-handed crab (Eriocheir sinensis),Letiobus cyprinelus, American frog

(Rana nigromaculata), Crucian carp(Carassisu auratus,), snakehead(Oxyeleotris marmorata), loach, catfish(Misgurnus anguillicaudatus, Clariasleatheri, Silurus meridionalis), soft-shellturtle (Trionyx sinensis) and ediblesnail.

Development of large-scalerice-fish culture

Although China is a vast country, ithas the world’s largest population andits land resources for crop farming andaquaculture development are limited forfurther expansion by area. Rice-fishculture is an effective way of landutilization for food fish production withnominal competition with otheragriculture activities for land and waterresources. Taking 1999 as example, thefish production from paddy field in thatyear was 650,000 tons. It wasequivalent to the fish production from86,667 ha of fish ponds with the yieldof 7,500 kg/ha. It is estimated thatabout 6.7 million ha of paddy field inChina has the potential for conversioninto rice-fish culture. If half of thesepaddy fields are used for rice-fishculture, it is equivalent to the fishproduction from 200,000 ha of fishponds based on the present-day fishyield level.

Rice-fish culture is a relatively easy,low-cost and low-risk entry point forrural farming communities to improvetheir livelihood and household incomewithout jeopardizing the sustainabilityof rice production. Compared withpond-based aquaculture, rice-fishculture is less restricted by initialcapital investment and laborrequirement. Rice-fish culture is nowused widely as an alternative livelihoodimprovement and poverty alleviation.

In the 1990’s, China has undertakena series of mass campaign of rice-fishculture extension. Several standardizedpaddy field renovation models wererecommended and widely adopted. Itturned out that farmers with theirpaddies renovated became lessvulnerable to flood and drought. Forinstance, in rice-fish-duckweed-lotus-water cane-chufa-vegetablesintegration, the recommendedrenovation includes an increase in dikeheight to 80-100 cm, the excavation of a120-150cm deep sump and 50-70cmdeep ditches. The sump, sometimes


brick and cement walled for durability,accounts for 7-10% of the paddy fieldarea while the ditch occupies 3-5% ofthe total area. Each hectare of paddyfiled with such renovation could storeup to 7,500m3 of water during rainyseason. The sump could be used asreservoir for watering vegetables in dryseason.

Effective extension service atvarious levels, financial support andincentive policy by government haveplayed important roles in the widespread of rice-fish culture in China inthe past two decades. At present, thegovernment has formed a nationalfisheries extension network andextension activities are carried out atfour different levels under the NationalFisheries Extension Centre, namelyprovincial, prefecture, county andtownship levels. In some places,extensions officers also help to securefish seed supply and marketinginformation for farmers. Rice-fishculture has been incorporated into theoverall rural development plan andagriculture development plan by manylocal governments. In less developedand remote regions, financial supportin the initial stage is a key factor tohelp the resource-poor farmers inpaddy field renovation and first runoperations. Financial support from thegovernment is usually delivered in theforms of construction materials andseeds, etc. Tax exemption is applied torice-fish culture in places where it ispromoted poverty reduction purpose.Such incentive policy should becontinued.

It is apparent that small-scale rice-fish culture can bring improvedeconomic benefits to individual farmerfamilies. With more than 60% of China’spopulation occupied in agriculture,there is a need for further extension onrice-fish culture among ruralcommunities on a mass scale, where itis possible, in order that itsdevelopment can benefit the economyand well being of the whole society.Only when rice-fish culture is practicedon a mass scale will its socio-economicand environmental benefit be realized.Therefore, the need in the immediatefuture for aquaculture developmentshould include rice-fish culture as oneof the top agenda items.

fish; smoked and marinated fisheryproducts; canning; silage; packing;quality assurance, HACCP and sensoryevaluation.

Available from: Directorate ofInformation and Publications ofAgriculture (DIPA), Krishi AnusandhanBhavan, Pusa, New Delhi-110012,Phone: 91-11-25731350, Fax : 91-11-25731282, http://www.icar.org.in/icar6.htm

Conclusion: Recommended. Thisbook provides a useful insight intomanufacturing processes and theirimpact on product life, quality andnutritional value.

Trochus hatchery seeding techniques– a practical manual

T.P. Crowe, M. Amos, P. Dwiono, G.Dobson and C. Lee.32pp.

This manual is written for thegeneral public, fisheries extensionofficers and artisinal fishermen. It aimsot provide a basoc overview of thebiology of trachus and its productionin aquaculture facilities. It alsosummarises the findings nd protocolsof the ACIAR Truchus ReseedingResearch Project in practical terms. Themanual contains sections on i) thebiology and life cycle of trochus, ii)hatchery production of trochus and iii)reseeding of trochus. The manualaddresses practical issues such as howto spawn and raise the shellfish,selection of suitable sites, size of

...continued from page 42What’s New in Aquaculture

developed from published materialsfrom our Compendium partners (AIT,IoA, NACA and WAS), andcollaborators (MRC, STREAM), withdiscussions on-going with otherpotential collaborators (DeaconUniversity, FAO, SEAFDEC, WorldFishCenter). Although it is CABI’sintention to cover case studies in otherselected countries more fully insubsequent editions of theAquaculture Compendium, it wouldbenefit the first release of theCompendium if it were to have widercase study coverage. I intend to“cherry pick” systems and issues ofparticular relevance and interest fromaround the world so do contact me ifyou wish to contribute.

Formats and examples of casestudies are in preparation. Each casestudy is to be brief, about 10 pages,with summarized text and bullet points.There will be a standardised table ofcontents for growout productionsystems although for other topics itwill be flexible because of diversecontent. Case studies will be richlyillustrated with photographs, tablesand graphs.

For more information contactMartin Parr at [email protected] for case studies, contactPeter Edwards [email protected] will receive a smallhonorarium to express appreciationfor their input to the Compendium.

Aquaculture Compendium - case studycomponent


trochus at release, how to improvesurvival and packing and handling. Itincludes a reference section for readerswho wish to explore topics in moredepth.

Available from the Australian Centrefor International Agricultural Research,GPO Box 1571, Canberra ACT 2601,Australia, Tel: +61 (02) 6217 0500, Fax:+61 (02) 6217 0501, [email protected] http://www.aciar.gov.au/web.nsf/publicationcategory?openform

Conclusion: A useful introductorymanual and a good starting point forpeople wishing to become involved introchus culture.


Symposium on Disease Problems inAquaculture: Challenges andManagement, 6-7 February, Mumbai,India

The Symposium is organized by theCentral Institute of FisheriesEducation. Themes covered in theSymposium will include: Emergingdiseases of finfish and shellfish;Finfish and shellfish immunology;Aquatic environment and management;Genetic selection and diseaseresistance; SPF stocks; Probiotics andtherapeutics; Epidemiology; Herbalproducts in aquaculture; Exotic andemerging diseases; Quarantine; Drugsand chemicals; Antibiotic resistance;Tissue culture in disease diagnosis;Finfish and shellfish vaccines. Formore information contact Dr S.C.Mukherjee, Director, Central Instituteof Fisheries Education, Versova,Fisheries University Road, Mumbai -400 061, India. Phone 0091 22 26363404,email [email protected]

WAS 2004 Special SessionAnnouncements, 1-5 March, HawaiiUSA

A number of special sessions will beconvened at the World AquacultureSociety Meeting in Hawaii, 1-5 March2004. People wishing to participate inthese sessions are encouraged tosubmit an abstract. Please note thatneither WAS nor session organiserswill be offering any support forexpenses to participate in specialsession sessions, ie. Participants mustmeet their own expenses andregistration fee. The special sessionsare as follow:

Economics & markets of marinefinfish cultureThe International Association ofAquaculture Economics andManagement (IAAEM) and theNetwork for Aquaculture Centres inAsia-Pacific (NACA) will be co-sponsoring a special session entitled“Economics, Socio-Economics andMarkets of Marine Finfish Culture” for

the World Aquaculture Society (WAS)2004 Conference in Honolulu, March 1-5, 2004. This session will cover allaspects relating to the economics,socio-economics, policy, markets, andtrade of marine finfish aquaculturearound the world. Selected papers fromthis session will be published as aspecial issue of the journalAquaculture Economics andManagement.

Computers in aquacultureThis special session is intended to be aforum for exchange of information onthe latest innovations anddevelopments for the practicalapplication of computers and theInternet in aquaculture and fisheries.Another purpose for convening thisspecial session is to bring together asmany individuals as possible who areinvolved in the development and use ofcomputer based informationtechnologies so that we may meet oneanother and discuss how best to movetowards integrating an internationaldistribution network for the everexpanding array of Web sites,equipment, software, distanceeducation opportunities and otherproducts and services being developedfor aquaculture.

Advances in aquafeedThis special session, organized byAquafeed.com is intended to be aforum for exchange of information onnew feeds and the latest technologyand nutritional innovations of practicalapplication to the aquafeedmanufacturing industries. Abstracts forthe Aquaculture 2004 meeting are dueby August 1, 2003. There is a sectionon the abstract submittal form toindicate that the abstract has beeninvited for a special session – pleaseenter: “Advances in Aquafeed(Aquafeed.com)”

Economics of shellfish cultureA session will focus on the economicsof shellfish (i.e., culture, management,etc). If interested, please go to theConference website for online abstractThis session is being developed underthe auspices of the National

Shellfisheries Assocation, which will bea one of the three major associationsjoining in the Aquaculture 2004meetings.

Aquaculture Without Frontiers - theAquaculture Work of NGOs inDeveloping Countries

An idea to form a new NGO, tentativelycalled ‘Aquaculture without Frontiers’(see www.was.org for further details),aimed specifically at assisting in thealleviation of poverty in developingand transition countries throughaquaculture, was put forward in akeynote paper presented at the 2003conference of the World AquacultureSociety (WAS) in Brazil in May 2003.

Recognizing the role of and need forNGOs to use aquaculture to assist inmitigating the projected shortage offish, a workshop on the aquaculturework of existing NGOs in developingcountries is being organized inconjunction with next year’s annualWAS meeting (‘Aquaculture 2004’, 1-5March 2004, Honolulu, Hawaii) with thefollowing objectives: i) to review theexperiences of NGOs in aquacultureand to identify potential futureopportunities; ii) to document theinstitutional experiences onaquaculture development throughNGOs; and iii) to understand theperspectives of governments anddonors assisting NGOs in this type ofwork. Attendees will include CaritasBangladesh, NACA, the World Bank,and the WorldFish Center. It is hopedthat this initiative will help to publicizethe significantly positive contributionsof existing NGOs and their donors toaquaculture in developing countries, aswell as assist in promoting theformation of ‘Aquaculture withoutFrontiers’. The abstract deadline forthis session has been extended to 1September 2003. Abstracts need to besubmitted to WAS www.was.org/SubmitAbstract.asp?Code=WA2004,with copies to the [email protected] [email protected].


New Zealand Aquaculture for the 21stCentury, 12 March, Auckland

Organized by the Asia-Pacific Chapterof WAS. The aim of the conference istwo fold. One to help New Zealandaquaculture with a conference thatfocus on all aquaculture industry inNZ. The second is to help networkpeople in NZ aquaculture and overseasindustry with the view of helping NZachieve its full aquaculture potential.The cost for the day is NZD $75 andaffordable room rates are available ifyou want to stay over night or theweekend. The registration forms will beout by 12 December 2003. For moreinformation or registration formscontact Robert Bishop [email protected]. Theprogramme is available for download.

Third Regional Grouper HatcheryProduction Training Course, 17March-6 April, Bali, Indonesia

The Third training course is tentativelyscheduled to be from March 17 - April6, 2004. Any interested parties shouldcontact Mr Sih-Yang Sim [email protected] to register theirinterest. The training reports for thelast two years are available fromnetwork website at http://www.enaca.org/Grouper/.

The Eleventh International Symposiumon Nutrition and Feeding in Fish, 3-7May, Thailand

International Symposium on Nutritionand Feeding in Fish (XI ISNFF) will beheld on Phuket Island in Thailand. Thissymposium will be the forum tocontinue scientific discussion on allaspects of fish nutrition includingcurrent knowledge and futureperspectives in plenary sessions ,workshops , oral presentations andpesters. In addition, emerging issuesthat relate to food quality and safetywill be addressed. There will be anopportunity to organize meetings todiscuss special topics that may lead tothe formation of networking groups topromote the advancement ofaquaculture nutrition science ,technological development anddiscussions on potential regulatoryissues where nutritionists couldprovide appropriate advice on policy .

Study Program on Marine FinfishAquaculture and Markets 2004,Guangzhou and Hong Kong, China, 1-7July

The study program is intended toprovide participants with an insightinto the live marine fish markets andaquaculture in southern China andHong Kong. The study program will beorganized by NACA in cooperationwith the Guangdong Dayawan FisheryDevelopment Center (Department ofMarine & Aquatic Products, China),Guangdong Provincial Bureau of Oceanand Fisheries, Guangdong FisheriesSociety, and the Agriculture, Fisheriesand Conservation Department (AFCD)– Hong Kong SAR. Tentative schedulewill be around July 2004 period. Moreinformation on this study program willbe provided on the marine fish networkwebsite when available. Interestedparties can contact Mr. Sih-Yang Sim([email protected]) to register theirinterest.

4th Conference of the AsianFederation of Information Technologyfor Agriculture and 2nd WorldCongress on Computers inAgriculture and Natural Resources, 9-12 August, Bangkok, Thailand

*Call for Papers and WorkshopProposals* The Organizing Committeeof the Joint AFITA/WCCA Congress ispleased to extend this invitation to allprofessionals involved in agriculturalinformation technology to attend theJoint Congress between AFITA andWCCA, August 9-12, 2004, in Bangkok,Thailand. Also, to participate asauthors of a paper to be included in theproceedings and to be presented orallyor at a poster session in keeping withthe theme of the Congress.Submissions for pre-congressworkshops are welcome.

Areas of interest include but are notlimited to: Information Technology inAgriculture, Rural Development andPoverty Reduction / Knowledge BasedSociety and Its Strategies/Policy;Adoption and Extension; AgriculturalRisk Management and FarmManagement; Decision SupportSystem and Modeling; E-AgBusinessand Production Chain Management;Information Resource and Databases;

Grid and Web Services; Field DataAcquisition and Recording; GIS,Remote Sensing and PrecisionAgriculture; Food Safety, FoodSecurity, Trace ability and QualityManagement; Education and DistanceLearning; Digital Library / KnowledgeRepresentation and Library Science;Water Management; MultilingualServices; Aquatic ResourceManagement; Bioinformatics; Birth ofFeathers. Abstracts can be submittedonline and more information isavailable from http://www.afitaandwcca2004.net/att.php. Fullpapers that are accepted must besubmitted in the appropriate formatbefore April 30, 2004.

AustralAsian Aquaculture 2004,Sydney, Australia, 26-29 September

Australasian Aquaculture 2004 will bethe first in a series of nationalaquaculture conferences to be heldbiennially near the major aquacultureproducing areas of Australia.Australasian Aquaculture 2004 will bethe biggest aquaculture conference andtrade show in Australia since WorldAquaculture ’99. This internationalconference and trade show will examinethe Australian National AquacultureAction Agenda and also provide awider forum for general exchange oftechnical information among producers,suppliers of equipment and services,researchers and policy makers.Australia is an ideal location for theevent because of its close links withNew Zealand, the Pacific Islands andAsia. Call for papers: Abstracts are dueby 27 February. For further informationor download the brochure from theNACA website http://www.enaca.org/AusAq.pdf (PDF 260 KB).

Or get the CD version - includes a free QuarOr get the CD version - includes a free QuarOr get the CD version - includes a free QuarOr get the CD version - includes a free QuarOr get the CD version - includes a free QuarterlyterlyterlyterlyterlyPublications UpdatePublications UpdatePublications UpdatePublications UpdatePublications Update

US$ 15/year in NACA member countriesUS$ 25/year elsewhere

A well-balanced diet is essential for our health. Hence the saying "you are what you

eat". However accurate this phrase may be, it does not cover the whole story. Because

an important part of our daily diet is produced by animals. A diet for which fish and

shrimp are of increasing importance. And, as you well know, their health also depends

strongly on their diet.

In other words: the better the feed, the better the food. Therefore, we promote the

production of prime quality fish and shrimp through improving the nutritional value and

guaranteeing the safety of our feeds and concentrates. As our studies have revealed

that this leads to less stress and diseases, in animals as well as in human beings. A

result we always strive for. Because we care.

Research has shown that you are what they eat.

www.inve.com

I N V E i s t h e p r o u d g o l d s p o n s o r o f

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