Perspectiyes and Economic Potential of Aquaculture of Tilapia : Experience in North-eastern Brazil Useful to Other Regions of the World

Brazil is an important producer and exporter of pork, beef and chicken, and fish is gaining way in to this field due to its gradual increase in production as a result of aquaculture. In 1996, tilapia was the mostly cultivated species representing approximately 32% of the total production of cultured fish. Hence, aquaculture, especially the culture of tilapia is showing considerable growth contributing significantly to socio-economic development and food production in Brazil as in many other regions of the world. Nevertheless, most of the consumers as well as the producers are continued to be misinformed of the positive aspects of aquaculture of tilapia, such as socio-economic development, generation of employment opportunities and foreign exchange earnings. Around 70 % of the country has a tropical climate, which favours the rapid growth of tilapia. Further, Brazil possesses a large number of inland water bodies, which represents approximately 12 % of inland waters of the world. As such large amount of aquatic habitats of fresh water is available for aquaculture. Tilapia is a major source of animal protein for to about 44 million people living in this region. The objective of this study is to evaluate the contribution of tilapia for the culture and capture fisheries in the north-eastern region of Brazil, especially in relation to socio-economic aspects. With adequate investment and management, aquaculture of tilapia can be successfully carried out in an environmentally friendly manner for the socio-economic stability in this region. The experience in the north-eastern region of Brazil will be very useful to develop tilapia culture in other regions of the world to combat protein malnutrition of the people and to generate foreign exchange through exportation of the product.

The Nile tilapia, Ornchronis niloticls is widely cultivated in Brazil as a pure or gcnetically improved variet! (GIFI or Chitralada) togethcr with two othcr introduced spccics.namely the Congo tilapia.TiLdpia rendalLi and the Zanzibar tilnpia, Oreochrotnis hornorun.Ttto hybrids.i.e., the red tilapin (Oreacltonit niLoticus X Oreochronis arreus) and the hybdd lilapia of the Northeast (Orcocirdrris hornorun X Oreochtunis fiiloti(:us), which werc produced for tlle first time in the Statc ol Cea|ii in 1972 afe also used in aquaculture in Brazil (DNOCS 2000).Inierest for lilapia culrivarion hlrs incrcased in the last nine yeurs due 1() fie introduction of the mrle produclion lechnology through sex relersal.With the development of this technology, individuals which can reach a size of ,100-500 g within ir culture cycle of one year in the sourh-eastem and southern regions of Brazil were produced-These fish fetch a high market price and are used in paid lishing activities.This has encouruged the expansion of cuhivation nor only exlensivcly bul also semi intensivcly in wuter bodies fefiilized \rith organic manure, intensively in "race-*,ays" and super intensively in floating r::t cag:s.
In 1996, tbe tir_,.rrnroduction in Brazil was around 19,200 tons.which conesponded to ''+'Z of the world production (Lima 2001a).From 1996 1() 200I, there lvas a nearly 3.5 fold increase in thc production of tilapia, although the area under aquaculture increased only by about 32Eo (Tablc 3).About 757. of this production came from the southern region whilc thc contribution from thc norlhrastem region was < l0E (Tablc 4)  19,200 26,250 20,238 21,128 35,,105 ,12,91E 58,265 69,912 25,33,+ 26,689 The development of paid-fishing establishments is among the main factorc that contributcd to the gro*,th of aquaculture of tilapia in the southern and souih-easlem regions of Brazil.Paid-fishing establishments are made Lrp of cither a single fishery with little infra-sfucture or nrany frsheries wilh more infrasffucture such as car parking, sleeping quarlers, lighting for night fishing, rcstaurants, car parks, playgrounds for children and adult leisure grounds (game roorns, etc.).At paid-fishing establishments til.rpia may be purchased for R$ 2.50/kg.A! some estitblishments of this nalurc in Ceard, where the extent is about 8 ha, xboul 1.000 kg of fish with prices ranging up to R$ il,fi)Ag were produced per "'eek (Silva 2001).On the other hand. in the nonh-eastem rcgion, there is an enormous potential to increase the prodLrction in large rese oirs by faltening tilapia in cages.Besides ihis, through the cullivation of lilapia in dug-out ponds in rural areas and frequen!stocking of public and private reservoirs, Brazil could become one of the laryest producers and exporlers of tilapia in the world.

N{arketing of tilapia Intemationsl mqrket
Japan, USA and the Europcan Union are the major impofte$ offish in thc world.These countries account for about 75% of the total imports which is valued at around US$ 2 billiorl/year (Silva 2001).
In 1998, tilapia imports in USA were around 24,000 tons (Table 5).In that year, Brazil exported only 1.27 tons (Lima 2001a).In 1999, the USA imports rcached a level of 37,570 lons of whole and cut tilapias $hich was equivalent to 60,785 lons of l;ve $eight (Silva 200I).The prices were also rcwarding, live lilapia fetching a price of USS 13.19 kg and cold fil1et fetching a prjce of US$ 14.40 kg in thc rctail market.In USA, among the culturcd spccies, tilapiu is the third most impo(ant species followed by salmon and shrimp.The leading country which exports ftozen tilapia fillets is Indonesia, while Costa Rica and Ecuador are the main countdes which erpod cold fillcts (Silva 2001).
The tihpia market in the European countdes is based almos!exclusivcly on imported products, as their tolal production is less than 360 t"rr.|er rnrum 'L.rnr l00lat.Total Fof the cconomic \iability of a{luaculturc of tihpia in Brazil.it is nccessary to pfepare a development plan and provide organizalional infrrslructure to implcment it.Further, providing technical assistance and support services and coordination of activities are also necessary' For the time bcing, already available organizalional structure for proccssing and exporting marine fish could be utilizcd for this too Ma*eting of tilapia in Bru.il In llrazil, imporlation of captured and cultured fish increases annualLy.Increasing demand for fish in Brazil suggests dra! therc is a high potcntial to rnarket the cultured fish.The vast polenlial for aquaculiure of lil.rpia in Brazil $ill result in the developmenl of a susteinable sector capable of supplying culiured llsh lo local as \\ell as intemalional markels Currcntly.the manner of rnarketing of cultured tilapia in the no heastem region ofBrazil is very precarious This adversely affecls lhe qualily of the product due !o lack of adequate infrastruclurc including fish entrepots, colleclion and resale sutions, fieezcrs and ice plants However' thcse faclors favour the intermediaries who keep a large Eo of the profit (Silva 2001).Thc interrnediaries rnonopolize up 1{r 72q. of the profits The wbolesaler sells a small pofiion of the product at his own shop and stocks them for subsequcnt buyers.Fu(her, the intermediadcs negotiate the price wjth supemarkets.fish shops and restauranls (Silva 2001).Thus' the price of the producl dcpends on those involvcd in the rnarket chain However, cultured tilapia necd not go through wholesale dealers and could be directly marketed to export companies.rctail vendors, restaunnts and consumcrs When tilapia comes to the market directly from the culture source' soon after being fished, thc fish .rcfrcsh and prescrved only by icing For the local market, frozen tilapia fillets packed in plastic bags could be inlroduced.It is possible for the producers of tilapia to set 257. of the total profu whereas in the poultry and pork sector, the E profit carned by thc producers is 107, ai lhc most (MAA 2000) 24,000 100 At the cold storage plant, conditions of the lilapia are verified beibre thcy are processed or sold 10 consumers or rctail vendors.This is imponant 10 negotiate a just price, for quality conirol and maintain good sanit y conditions.
Norm,rlly.the markels in Brazil are not geared to accept llrrge quantilies of tilapia coming directly from the fafms!as there are not enough cold siorage planls.ln addilion, tilapia is not a very popular lish among mon of the Braz;lians.Howerer, in tlle nodh eastern region of Brazil' lhere is a prornising market fot tilapia due to high demlnd from institutional reslaumnts (i-e.those in service enlcrprises, barracks, hospilals.schools e1c.).and sDack bars (Siha 2001).Neve hcless, in ordcr lo improve product quality and commercial organization, it is necessary to analyse the nlture and availability of intemal mrkct and elaboratc proposals for its dcvelopmenl.Tbese studies should include surveys on nxfket procedures, consumcr demand and lhe competition $ith mafine fish Competition with other species There is slill much to be done 1() compete *'ith oihcr imponed fish, which currently dominate ihe Brazilian mrket (Lima 2001b) N{anual processing plants \''ith a capacity of handl;ng 40-50 tons of cultured tilapia per week have been conslructed in the States of Paran, and San!a Catarina.
Numerous small producers slice tilapia to sell in local markets Tilapia $cighing 350 -500 g are filleled rnanually.Each fillet weighs 56 -8,{ g.Tilapia fillets are sold hesh or frozen.Tilapia is also sold as whole fish on ice to neighbouring markets.
Culturcd tilapir are also sold in strcct fairs, city markets, fish shops.supermarkets and other places as whole fish at a price of about RS'{ 00,4(g and as ftozen illets at a price of RS ?.E0/kg.Furlher.live tilapias are also sold in some fish shops in large nonh-easlem cities. such as Fo(aleza and Recife (Silva 2001).
The main obstacles for competing at the intemational markets are associaled with incipienl struclurc of research institutions, irsufflcient knorvledge on the market chains both al the local and intemational levels, iack of infonnation regarding production costs and compelition from other tilapia producing countries.Howcver, for the intemational market, it is necessary lo develop a slralegic proposal, which guarantee the nraintenance of the quality of the product throughout lhe entire process.from cultivation lo processing.For this, it is necessary to consolidate on a HACCP system' lvhich \rarents quality during all stages of the processing procedure Besides this, it is impoftan!!o develop a strategy to popularise Brazilian tilapia by participaling in fairs, congresses, and by direct intervention with rmponels, Consumption of fish in Brazil ln 1998, 40000 tons of prepared fish products (i e ' fish-sticks' fishburge$, nuggets.etc.) werc impo(ed to Brazil for local consumption (Lima 2001b).
Pijr capita consumplion of fish in Brazil, is around 6 kg per annum' which is rery low compared to international levels Ncvenheless there is high potential to increase this (Ribeiro et al 20 (10).The Brazilians consume a lolal of,161,800 tons offish of which 90 19o are marine fish (Tablc 6) However, in the norlhern region of Brazil annual per capita consumption of fish is around 55 kg mainly due high availabiliiy of fish caught from the Amazon (Lovshin 2000) In the nonh-eastem region, pcr capita fish consumption is only arcund 6 8 kg/year (Silva 2001).However' th; World Health Organization (wHO) recornmends a minimum per capita consumption of 15 kg of fish per/year.Accordingly, the total annuxl requirement oi fish in the norlh-eastem region ofBrazil is about is 670.500tons.
ll ir e.rirruted lhat Jboul o0 ol lilJfia proJuced in rhe re'erroir' in the noflh-easiem region is consumed in the villages located near the reservoirs as there are not much food options for the riverbank populations and also beceuse the prices are wilhin reach for most consumers (Silva 2001).Nevertheless, the north eastem rcgion purchases a considerable quantity offish from othe.regions, i.e., from the southem and soulh-eastem regionr.and:rlso lrom other \ounlries ln the mefopolitan region of Forta]eza in the north-eastem regron, thcre are nearly 100 institutional restaurants' which serve more than 60'000 meals per day, \ 'ith fish being scrved an average of 2_3 times per month in podons of 180-220 g per meal (Silva 2001) As such, this markel alone bas a demand for about 500 tons offish per year' Disintegration of the purchasing ability of the middle class may influence the fulLrre internal dernand for tilapia ln any event.this sector should be prepared 1() function with more operational efficiency aiming at reducing producdon costs as well as the markel price oftilapia

Socio economics and environm€ntal consideralions
Approximately 44 million people live in the no h-eastem rcgion of Brazil.There is a high regional diversity in Brazil with regards to hcaltb.cuhure, industrializ.rlion.populadon densily and othel socio economic factors.
A large segment of the populalion in the intcrior of lhe north_ eastcn regioD halc no income at all, or suNive with an income of less than USS 2.00 per day (Silva 2001).ln this region.61 57o of children who are less than 6 years of age are in families whose per capita income is less than half ofthe minimum reconmended wage (Carvalbo 2ml) The State of Cear, is in a semi-arid region and is characterized by scarcity of rains-It is one ol the major faclors responsible for low productivity and less availability of food resuhing in high rate of poverty and hunger.
Exodus of people is very frequent from the rural arcas where there are litlle labour options.Funher, thc fishery resources also appear to be depJeting.Lack of infbrrnation on produclion costs and financial retum has also resulted in the wifidrawal ofinvcstment in this sector' To make ma(en worse the greenhouse effecl has also negalivcly influenced the ecosystems bolh in the te|reslrial and aquatic environments The productivity potential in various regions has declined year by year.The rivers have dried-up and the agricuhural areas have become unfertile resuhing in grave problerns for socio-economic development Due to lack of rain, nulrienl inflow into rese oirs, lakes.rivers and coastal marine *,aters has decl;ned resulling in low biological productivity leading to low fish prL\]uction.
In Brazil, 80% of the sewers djscharge their effluents without any reatment.The government and local administration prefer to invest in ostentatious constructions, which bdng in mole votes.It should be cmphasized that effluents must be trelted prior to discharged into the environment.lt was within this conlex!that the sustainable use of biodiversily was reconrmended at the Biodivcrsity Convenlion held in 1992 in Rio de Janeiro where 172 counffies participaled The decline in the production of aquatic organisms in Brazil sounds as a waming signal to the lack of interest by the authorities with regards 1() .usr.linJble usc ,rnd conser\ation ofaquilr.rcsources in reservoir\.ri!er5 and oceans.lt is only lhe researchers who fore\\'arn the dangers lhat lesult from unsustainable use of such rcseurces.

S u stainab le de I e lopme nt
It is necessary to generate new employment oppollunities for the increasing human population to provide means for their suNivai lf not.some othcr nleans should be dcveloped for their mainlcnance.Fishing, mainly in reservoirs in the north-eastem legion of Brazil, is an impo(anl aclivity that supplies animal protejn to the rural populations at ir lolv_cosl.Therelbre, rural pcople could be nourishcd and sufiiciently catered by naturc while nlaintaining {hc traditional cullures.Hcnce.by utilizing the naturc in a sustainable ranncr, food produced in a particular region could be used by the pcople in th.ri are.r. Nourishment is also associated with the needs of the people and their culture.ln the north-eastem region of Brazil, main source of animal protein has been meat by tradjt;on.Although anirnal husbandry aciilities ilre caricd out, it is necessary to car) oul fishing too as an important altenrxlile mcthod of generating anirnal protein.For this, the conmunities should be organized to manage lhe capture fisheries, carry out aquaculture and arketing along $,iih the proteclion and conservation of the environment.This has beco,ne:''cessary because fish production in the rese|loirs of Cearii State har .!tcii,red in certain regions even to x level that '1 s noi sufficient i.' r: .,iLirr iocal rural communities.
The research lli.sho$n tbat the chrotic situalion of thc Ccarii Slate may be overcome b] aquaculture deveiopment, $hich will generate cmploymen!opportunides and income to the rural cornmunity as well as animal protein while maintairing the cultural eating habits based on lhe cuLtivation of aquatic orgrnisms and fishing.This indicates thal ftere is a possibili!y of utilizing aquatic resources and employing unoccupicd lands for profitablc producti\e rclivities, with the involvement of the rural co munily tbrougb the developmeni of cornmunity associations \\'hile developing an ecological conscicnce.
The rapid expansion of aquaculture can lessen socio-economic problems faccd by poor rural conrmunities.However, it is important to give greater consideration to elaborale on the necessary production methods to mainrain economic independence and self sustainability.Furthermore, it is necessary that all peoplc of the Cearil State unite their strenglh and knowledge to produce sufficicn!raw material for aquaculture.ln@nse research and invcstigations should also be carried oul so that in the near future there will be sufficient production of fish and other aquatic organisms in the State.It is also necessary to pay attention to environmental safely and conservation of nalural lesources.Within this context, if fishing in the reservoirs is carfied out lvifiout over-exploiting the natural stocks, it will be possible to utilizc these resources in a self-sustained manner' lf not, rhese resources will graduall) diminish creating considerable socioeconomic problems, Fcasibility ofaquaculture of tilapia in rural areas in Brazil The rcasons for bctter establishmen! of tilapia in some rcscrvoirs in Brazil than in othcrs.ha\e becn jdentified as follorvs (Silva 20(ll) l) watef quality in reservoirs in the nonh-easlem rcgion of llrazil r. rJcrl lo-r trpi.lgro$ rh of IilJpid 2) The fish sfecies in most icservoirs arc predominantly camivorous, resulting in an elllcient conlrol of tilapia populatlons, 3) Commercial fishing iD populalions nost reservoirs help to redLrce tilapir 4) Polyculture of lilapia includirg common carp rcsults in high yields.
hybrid with scvcral species of fish feeding $ith lolv protcin diets also 5) Moreover, in most regions of Brazil, $cre is a tropical clinrate tbat allows aquacullure oftilapia throughout the ycar' Prolein malnulrition prevails in many parls of the north-eastem region of Brazil and fish c.rn bc used as low-cost protein sourcc to overcome this Problem-Bruzil is an i po(ant pfoduccr and expo cr of gnins such as soy and com lhat can be uscd as supplcmentary fecd for culturcd fish Tilapia possesses desirable charactefislics for aquaculturc (Tables 7  and E).lvlainly bccause of its satishctory growtir and good quality meat.aquaculture of lilapia has sho*'n promising perspectives Sxlisfactory results havc been already obtained b-\, various prirale entcrprises showing exccllcnt economic viabilily.Due to lack of dirulging mechanisms and operational support, a gfeater dissemiration of thesc results has not been possible.
Besidcs this, polyculture of tilapia hybrid with fish spccics such as tambxqui, conlmon carp and, pirapitinga, with supplementary feeding with low-prolein has resuLtcd in high conversion efficiencies (Silva 2001) Until reccntly, NiLe lilapia was tbe most favoured spccies among producers Howelcr, cultivation of red tilapia is also increasing rapidly due to high market demand.Among some of the qualities thal make tilapia a suileblc candidate for intensive aquaculture are high food conversion efficiency.high profitabilily, resislance to diseases, adaptation 1r) various environmentrl conditjons and consumption of low-priced food (Table 8).However.Reproduction during the first year of life is a problcm aquaculturists as this will reduce the rate of somatic growth This can be overcome by monosex cullure or using CIFT tilapia Species Score (0-10) faced by problem

Cultitalion adwntages
Preference for tilapia as al1 cdible spccies has $own significantly in the recent past in the north-eastcm region of Brazil as well as intemational\ (Table 9).Within this context.a sustainable aquacultLrrc of titapiir with Iow environrnenlal impact appears lo highly be required Information relaled to cuhivalion.which is vital for the success of an-v program ofaquacullure is also available at present The advanrages that Brazil has for aquacuiture oflilapia are listed in Table 10.
Fingerling production fiiere are 30 aquaculture strtions in the north-eastem region of Brazil of which two are privatel] owned and 28 are public (Silva 2001) These sutions are capable of producing approximately 1505 million fingerlings/year, w;th an average of more than 5 million fingerlings per sn;on per annum.These stations are spread throughout the droughtslricken Cearii State.
During the 68 years from 1933 to 1998, more than 2E6 million fingerlings belonging to 3l species have been produced in the aquaculture station" in the norlh-eastem region of Brazil and during the 13 years from i987 to 1999 more than 95 million lingerlings' which is about 337' of the total number prcduced have been stocked in the reservoils of Cearii state (Table 11).It is estirnated lhat a total of 210 5 million 6ngerlings of Congo and N;le tilapias are needed, annually for the reseNoirs in the norlh-eastem region of Brazil (Silva 2001) of which 28 1 million are required for the re;ervoirs in the Cearii State However, aquaculturc stations in lhis State can Brazil has for aquaculture of tilapia (Source: 70 '; of the country has a lropical climatc which favours thc rapid growth of tilapia.Brazil possesses hfge number of inland water bodies, which represents approxinutely l2 t/.ofinland watcrs ofthe world.As such a large amount of iiesh water habilrls is available for aquaculture.The country is self-sufficient in gfain production.Therefore.tilapia cuhure rvill b€ of added adv.rntrge 1() provide animal prorein ro the nation and eam foreign exchange by exporling thc excess producllon, High amount of incidcnt solar radialion resulting in high primary productivity in aquatic ecoslstems.Autonomy fof industrialized tilapia cuhure wilh govemment supporr.Alailabilii) ofa nationalizcd local tcchnology.In some projects, higher pfoducti\'ity th.rn some of the best ones in the lvorid \ras obtained using local Iechnology.Prcsent status ofcapturc snd cultur€ fisherics in the north-eastern region of Brazil Therc are approximetely 60.000 public and private rcse oirs in the north-eastern region of Brazil.which colef an arca of around 800,000 ha The estimated fish productioD potendal of these reservoirs is around 650,000 tons/year (Gurgel 1998).This region holds the largest volumc of drmned up \\'ater in semi-arid rcgions of the world.Almost all these rcscrvoirs are colonized with tilapia, indicatiig its importance in inland fish production.Siha ( 2001) suggesled introducing 13 species of fish including Congo and Nile titapias in the reserloirs of this region.The recornmended minimum length of the finSerlings is 60 mm.Thc presence ol predalors.including piranhas, seems to affect lhe tilapia produclion.Yct, according to Sil\a (200I) thc presence ofprcdrlors has, at !imes, contibutcd towards the control of population size of lilapias, which rill eventually resull in thc production of large sized fish due Lo enhanced growlh fitte.Predation due to conrmercial fishing also contdbutes in a similar nunncr.About 44% of the fingerlings produced by piscicullure stations is Nile lilapia (Silva 2001).This indicales the impo(ancc of tilapia in rcservoir fishery production in this region. From 1979 to 1998 the ntan number ol fishermen at thc public reserloirs in the nonh-elslem rcgion of Brazil was 3.123.Their mean annual catch was 3.6 tons per fishermen of which tilapia contributed for L3 tons (Table l2).
The mean fish production in the reservoirs in thc semi_arid northeastem region of Brazil is around 118.2 kg/htyr.The Jaramalaia rcservoir in the S1a@ of Alagoas recorded fie highest fish productiviiy of 1,989 kg/ha/yr.About 607, of the fish produced in the reservoirs is consumed locally (Gurgel 1998).The average production of the shallo$' feservoirs in the north-eestem region, which have a mean depth of less than 2 m. halcheries and ponds $hen stocked with tilapia hybrid is given in Table 13.
Aquaculture of tilapia generates employment opPortun;ties and income !orural population.lhus rcsulting in well-defined socio'economic benefi1s.It is estimated that about 50.000 people depend directly on fishing in reservo;rs in the semi-arid nonh-eastem region of Braz;I.With an average producdvily of 1.300 kg of ritapia per fisherman/yr.which is marketed ai R$ 2.50,&9, the annual average income of a fisherman is estrmaled to be RS 3,250.{X),which is around RS 270.00/ monrh.However, in the real sense, it is estimated thar the fisherman's share is merely 28%r of lhe Iinal rerail price oftilapia (Silva 2001) In 1986, the pubLic reservoirs in lhe Stale of Ceard produced over 10.(100 tons of fish (DNOCS, 2000).Ho*,ever, from 1991 ro 1996, it has decrcased.dnd froln 1997 it hlls again incrcased (curgel 2001).This increasc is bclieved to be mainly due to an incrcase in the production area (Tablc 1.1).However.according to Silva (2001), in some reservoirs lhis increase is due !o thc introducrion of O. xiloricls.In some reservoirs 100i.increase in fish produclion has been observed after rhe introduction of this specics (Silv.r2001).l?These obsenations indicate lhat in the north-eastem region of Brazil, the reservoirs can play ln imponant socio-economic role in a shot{erm rufal development programmc by effcctive utilization of local resources lhus opening nerv economic niches and promoting oppo(unilies for fishing and aqu,rculxne with sigDifican! eemings lbr lhe regional economy l8 ii.A lragashi et aL.

Production persPectives
Fingerling prcduction It is enrisagcd to incrersc the fresh water fish production in the rescrvoirs in thc north-etsl.rnregion of Brazil to 176'000 tons/yr of uhich 170.000 tons are expected ftom net-cagc culture and 6000 tons from orgxnized capture fisheries in public reservoirs (DNOCS 2000) For this' 630 million fingerlings lvill be required annually The auterchy hrd comnrilted to increase its presenl annual ploduction of 25 to 75 million fingerlings.and thc res! has to come from privaie enterprises (Si1va 2001) Ar'dilttbilit! of land an.I water Due to the inconsistency of rains, the best way to guarantee a continuous supply of $aier for agriculturc and aquacukure is by conslructing reservoirs rhat retain rain water for lalcr distibution during drought periods as done in many Asian countries including Sri Lanka, India and Thailand (De Silva and Amarasinghe 1996) Ncvenheless, studies done in the early 1980s sho$ed lhe feasibility of carying out irigation projects in a ,15,1,687 ha aret in the droughf stricken nonh_eastem region of Ilnzil (Silva 2001).lt has also bccn shown lhat around 9100 ha' which is nol arable due to salinization, could be used for aquaculture to produce around 636000 lons of fish pcr annum (Siha 2001).The agriculture and aquacuhure can bring about significant socio-economic changes in this arca

E nvircnm e ntal p rote ctio tt
Emphasis should also be given to canying out aquaculture activitics witbout significant ad\'crse environmental impacts The curent environmentll legislalion should also be thoroughly studied and adhered to.
The government and the conrmunity havc a fundamental role of protecling the envircnment of reservoirs.rivers and lakes as thcy are iommon pool resources.In tilapia culture, it is necessary to consider the legislation on $ater menagement, coastal managemen!and environmental protection ;n order !o achieve a sustainable socio-economic developmcnt

Net cage cult re
The north-eastern region of Brazil is blessed $ilh environmental conditions suitable for nct cage culture in reservoirs Funher.researches have shown tha! there is a high polential for intcnsive pisciculture in presently unexploited water bodies in the no h eastem region Within this context, tilapia produclion in nets cagcs may become an excellent option to make good use of reservoirs and eslundne arens in this region However, the produclion cost ofnetcagesis higherthan thal of eanhen ponds Onlhe othcr hand.fish cuhivated in net'cages grow fieir flesh is morc tender and lastier ihan those l9 faster and it is believed that of captured fish.
Q alit! of nfe of the rural poor it is worrh cmphasizing that tilapias culture in reservoirs is of great importance as those \lho coDsume these fish have a very low income and a low quality of life.Due to the existence of capture fishedes in public and private reservoirs and the low price of tilapias.a large segment of thc northeastern populrtion rvhere around 51.000 pcople depend directly on fishing has irccess to animal protcin (Gurgel 1998).

Slrategies for manageme nt
In the reservoir fisheries of the north eastem rcgion.wives and children of the fishermen are also engaged in fishing activiiies such as catching of fish, fish processing and repairing fishjng gear.Since there are nearly 5500 fishermcn invohed in frshing activities in the 94 public resen'oirs in the noilh eastem rcSion of Brazil, assuming that there are 5 mcmbers in a fishing farnily in average.nearl!27500 people in this region are directly benefited by fishing in thesc rcscrvoirs (Silva 2001)-Value addition through processing lecbniques is also necessary.This rvill fulther enhance the employment generation and income to the local cot nuntly.
Hence, by incorporating lilapia aquaculture in rural development progranxncs.rncome of the rural communities could be increased.This will contribule to enhance their quality of life in addition ro pfoviding animal protein to combai malnutrition.As such.thc cxodus of people from rural arcas miy also be minimized.
The number of professional fishermen in the public reservoirs in the nofth-eestem rcgion ofBrazil is obsc ed to be decreasing in the recent pas! probably due to the shrinking of reservoir'area caused due to the irreguladty of the rriny season, low fish production caused due to over-fishing and bashiul stocking programmes (Silva 2001).
The problem of declining water level in lhe resen'oirs may be pa(iall) ovcrcome by the transposition of hydrographic reservoirs as done by the Valley of Sao Francisco Developing Company to rivers of the semiarid region.
ln ordcr to meet the demands of the people, the Valley of Sao Francisco Developing Company devclopcd lhe Semj-arid Project, with an idca offctching water to the reservoirs ofthe River Parani basin and Fumas reser!oir in -\4inas Gcrais.
Funher, there are several other projecls, which show the possibility of generating wealth and getting rid of poverry in lulal areas.Neverthelcss, lhe colonies and fishermen s associirtions of lhe rcservoirs must be strenglhcned !o meet thc social requiremsnts such irs medical assistance, elenrenlary educalion.etc and to encoumge thc flow of credit and lechnical assisrance into the fishing communily (Silva 2001) Despite all thc advantages in fishing and aqurculturc of tilapia.recent economic development ir the Shte of Ccarri is based on generating revenue for the large enterprises and companies located in other xreas of Brazil On the othcr hend.if .lnorganized and planned development policy is implemenled for tilapia production.the semi-arid nofih-eestem rcgion would nol depend on government aid.Thus. the Sovemment should provide Sreater incentives to thc families of this semi-arid region through lilapia cultivation projecls.*,hich will also belp to prevent rural exodus.It is true that some of these protrams have not shown satisfactory results duc to lack of resources.Nevenheless, tilapia contributes towards the reduction of rMlnourishment of the rufal conmunities.There is a need to apply technology generaled through research.improve govemmenf offices and provide more investment by employing qualified personnel.Futhermore, fiscal control and administration of rescrvoir fishing canied out in thc past must be Investments for tilltpi4 cuuurc Production cosi of a cultured species may vary from region to region due to differences in clirnatic and topogrphical conditions.technology applied, and the dislance from culture areas to the site of seed production and to the market.It can also vary from farm to farm within the samc region due !o differences such as l.lrm size and the technology applied.The major costs involved in the aquaculture of tilapia include lhe costs of conslruction of ponds, food, fertilizer, aquaculture equipment, labour, property leasing, packng.processing and distribution Fish cuhivation in cages originated a1 thc Delta of the River Yanglze in China over 700 years ago.However, tilapia cultivation in cages began in the USA and the Ivory Coast in the 1970s.This technique has spread throughout the world now.
The decree thal regulates lhe use of federal public waters for aquacullure in Brazil was signed in April 200I According to this decrce, action has to be taken to populerize lilapia cultivalion in net cages (Ostrenskey and Borghelti 2001).
A system consisling of 32 individual net cages is considered as the minimum technically feasible size.The size of a net cage is around 2m x 2m x 1m.The economic cost tjenefit analysis involving intemal retum rate, levelling point, capital retum rate, pro6t and invested capilal retum Tild7ia in Brd.il time indicates that aquaculture in net cages is feasible and profitable (Silva

2001).
The tilapia llrgcrlings of 2(!100 g in qe;ghl take 3 -6 months in ner cages to re;ch th; markelablc size of 400 I In pond culturc' such fingerLings take a longer time to reach that size.In order !o get high quality individuals.fingerlings should be purchascd lfom companics that wanant lheir good lineage.
Administralion of cullivation in nct cages is also is simple The animals may bc fed tltce lirnes a day \ith floating fomulated fced During harvesting all the tilapias could be caught easily from the nel cages Tle production cost of tilxpla in nct cages is approximulely Rs 1.3?/kg.Thii amount is 20-307.higher than the production cost in pond cullurJbecause in net cages tilapias are exclusivcly led on fomulated feed $hile in pond culture fcrtilizrlion nray also be carried out to generate natural fo;d.One kg ofcultured tililpia could bc markelcd at a price ranging from RS LE0 to2.50.
Net-cagcs should be inslalled in places where therc are no strong cufients and minimum depth is 2.5 rn Funher, they should be inslalled away ffom the routes of boats and .iet-skisas such activilies may cause strc;s 10 the fish letarrling their gro\\th A legal aulhorizalion is also necessary to install nct-cages.Ono & Kubitza (1999)  Sonre producers rl.ly obtain '100 kg of fish from a net cage of 2m x 2m x lm in evefy ,1 months.Thus the annual production from 100 net cages of that size would be 120 tons According to Silva (2001)  According io Silv.r (2(l0l).the capiml inveshent requircd for the consruction of a I ha pond and to purchase equipmeDt required for the aquacuhure of fish in that pond is arourd RS 3.1,200.20(Table l5).The annual pxrduction from this I ha pond is cstimatcd to be 27 tons.As such the annual income is estimated to be R$ ,{8,600.00 from a t ha pond if fish are sold at RS 1.80 per kg.
T.rble 15: The capital inveshenl required for the construction of a t ha pond and to purchase equipnren!requifed for aquaculture of fish in that pond in the state ofCeafn (Soufce: The annual operurjoral cost of aquacuhurc pond of t ha stocked with male 1t-ile tilapia in the Stxte of Ceaii is around R$ 44.000.00 (Table 16).Thus thc annual profit from t ha pond is afound R$ 4600.(10*hile the minimurn profit from 100 net cagcs wirh a lotal area of400 mtris around RS 25,900.00.ln the recenr past, the North-east Constitutional Fund has been the mein source of financial assistancc for the capture and culture fisheries in the nodheastem region of Brazil.Sone funds were nude available by Banks such as Bancos do Nordeste (BN) and Estaduais.Credit lines are also availablc for lhe aquaculture of lilapia in the North-eastem region with pirlment offcrs of up to 12 years, .1 year deb! delay and interest rates of 5% per annum (Silva 2001).
Ho$e!er.for more cffective aquaculture production, more credit facilities !o the producers, more unity enong institutions, better incenlives for research and aquaculture cxtension and better lraining for aquaculturists are required.It is also necess.rfy to irnprove the nutritional quality of the diet givcn to culiured tilapia.The formulated feed should be prepared using low cos! ingrcdienls.The formatted fced should bc incorporatcd wift additives lo rcducc disease fisks and growth promoters to enhance growth and survival.Furthcr, aquacultufe should bc carried out in an environmentally fricndly manner.lt is also ncccssary to develop suitable fishing icchnologies in reser\'oirs and rivefs blsed on scientific rcsearch that rvarrant equilibrium bctween conseNalion and harvesting of aquatic organisms.
Conclusions According io the information already available, it appears thtt with the development of aquaculture ol Nile tilapia and capture fisheries in the reservoirs, it will be possible lo alleviale povefiy and overcome the uncqual distribulion of income anrong the rural commun;ties in the north-eastem rc€lion ol Bf.rzil.
Thus, with the inplcmentation of new appropriate aquaculture programmcs, tbe living conditions of lhe rural communilies in the interior of lhe nodh-edslem region of Brazil could be improvcd by creating employmcnt oppodunities.The tilapia produced by aquacuhure can bc cxported, thus conciliating a more favourable balance in the economy and distribution of benefits within the region.One of the basic objectives would also be $e integralion of inira and inteFfegional markets.which would subsequendy lead to a reduction in ihe prices of cultured fish to a level thal could bc afforded by the rural topulation.By intensifynlg production in reservoirs, the rural villagers could become lhe supply centres of fish for local and international markets.
Hrrvesling tilapia irom reservoirs is finite due to natural bioecological limitations.Due to this inevitable siluation, hopes are placed in stocking reservoifs and carrying out aquaculture in ponds and net cirges.Therefore.another imponant objective is 10 increase the production of tilepia lingerlings in the rcsearch stetions in order to provide lhe sufficient number oF fingerlings rcquired for stocking in reser\oirs, ponds and net clges.
Based on the present studies, it can be concluded that lhere is a great potential in the nonh erstem rcgion of Brazil to increase aquaculture production of tihpia, which would help to enhance the living conditions of the rural pcople.

,{ckno$ledgement
The audlors are grateful to Professor C.H. Femando, University of Waterloo, Canada for suggesting to publish this paper in Sri Lanka.Thenks afe also due to Professor Jose Tundisi lnlemational Centre for Ecology , Sao Carlos.Brazil, who translated the paper from Ponuguese to English.

Table 3 .
Tilapia production and lhc area used for aquaculture in Brazil from 1996 to 2{)0I (Source: Lima 2001a).

Table I L
The number of fingerlings produccd by piscicuhure stations in the norlh castcm rcSion of Brazil and stocked in the reseNoirs of Cearii State from 1933 to 1999 (Source: DNOCS 2000). .

Table 13 .
Fish production in the leservoin.hatcheries and ponds in lhe north-easlern region of Brazil with different culture regimes (Source: Alves 200r).

Table 1 .
1. Fish produclioto 1999blic reservoirs in the State ofCeara' liom  1989to 1999 (Source: DNOCS 2000) more than 150,000 tons of lilapia could be produced annually in ne! cages usrng only 5% of the water area of the public resc oirs in the nonheastem region of Brazil.Ifthesearesolda!.rpficeofR$ L E0 per kg, the arn ual income from net citges could be rround RS 270 million.