Maximum utilization of the vast brackish water areas constituted by the various estuaries, swams, inland bays, tida1 pools, lakes and brackish waters

George, M J

Mohamed, K H

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UT1LrZATION OF BRACKISH WATeR AREAS .FOR PRAWN CULTfJRE by M. J. GEORGE* and K. H. MOHAMED* Central Marine Fisheries Resc(trch biJtitute, Mandapam Camp MaJdm~m utilization of the va.st brack i~h water areas constltuted y the varions. e.stuarlt;s, &Watnp~. i.n~and h<U!. ida1 po~Js. I~k~s .a.ncl \;Iac~'waters a\ops tbe en~lre coastllde pf Indla for cul~l\'atiOll of prawlls under controJled conditions r e.quires very urS nt eon ideraiion in the-context otincTe;i!lcd food p~\)duction in the c-Quntry. Afthougb a small portion 9f these areu., ¢$pecially those in Koral!', ;lre being utilised for captu{e of praw[ls by a specJaJ tlldigcll<!US proces c~~le·d fiJt.t;alioll, vast stretch~s ofthi;SG back~te"rs and esttlnr/es tm remam unlit "zed. These arct\S In n'to l cases provide: ijiologrealJy pot III envitoDlDent ( r healthy growth. of /lla/lya pecie:s ot fiShe. prawn!> i\nd crab. Edsting knowledge about the life. Jti~toric:s and other biological tt pt;cts Of the twO Va.rietie -f pJ1lwns, uamt:1j tllCllilarine praw11,.S of the family P<;naeidae and m river prawns or ih fa.mily Pa:lat;lno.nilil\c;;tr re-viewed. In thIS context Ihl} reoent finding that shQrt·dur~tion culwre yields better pravm calche.s in the It ddy lield. prawn filtration Pfllctic~.s of Kern/a bus ber:n appr lsed. ;pos-sible mean of in reased utilization of back.water lIrellll for p~wn cu1(me and US~ of M(lCfOQrat:iIiulfI spp. for culture and tlansplantatlon to river s)'stems where they dQ not occur are indiCllted. INTR.ODUCTION The brackish waler areas of India may be grouped under lWO C ries-, namely open e tuaries and enclosod brackish waters. Uod'er category may be included tne typioal estna.ries of civet mOllths, wa.ter lakes Ilnd backwaters. Thes may bo either perenniul like th tic delta and tbe backwaters of Kera..la , here there islIow of wetter all round. ot :seasonal like tbe mouths of many of the maHer river and lakes which set isolated from tbe ea by llarrow sand b.ar and du.ring the summer months. The econd category includes th of estoaries. lake and backwaters teclaimed under var:iou paddy lields adjoining the Kerala backwaters and lhe low.Jying r'eclartlattonin the Gangetl.c dolt a in Ben8al belong to this type areas tbe culture practices of 'prawns- of marine origin are earried . . limite-d. Cx.tellt at present. About 11 000 acres (4.400 ba) of p ddy fields forming water areas in Kerala are pres¢ntly utilized fo a lucrative prawn ceertain months of the year. The fishery is seasonal and is ci,lrried *Present address: Central Marine Fisheries Research Substation, ~rllakul.111 BRACKISH WATER AREAS POR PRAWN CULTURE H5 ths of the year when the fields are free from rice cultivation. This fishery generlly described as a mere process of trapping of the juveniles of certain ,.T1["IH>V'~ prawns and the operations have been described by several authors 1937; Menon 1954; Gopinath 1955; Kesteven and Job 1957). season lasts from November to April every year. The catch per acre from 300 to 900 kg. The fishery is essentially a trapping of the fry and of. the prawns brought in by the tidal action. Recent experiments by the CentraJ Marine F;~heries Research Institute has shown that it looks like a trapping mechanism, some amount of culturing of the prawns takes place inside the rice fields. According to George et al. e1these paddy fields are not merely a part of the trapping mechanism provide an active and suitable biological environment for the life of these prawns". bhasa badha fisheries described by Hora and Nair (1944) in the in Bengal is another fishery where some sort of farming is carried in the paddy fields of Kerala mostly prawns are caught, in ns form only part of the catches. Due to the tidal action the maoy of the rivers andereeb in the e tUllrille arl<3 of .Bcugal get silted \lP and iu due coorse such areas aTe reblaimed for a,griculturaI by pUlting up bunds to keep ,away floods aod J dal water. Some su,ch recl.aimed areas which are t{)O low fOT cuJtivatioll are uSllally fish fa(ming. Many of the reclaimed areas where cuUiValioJi is provid~d with an additional outer bund and the low-lying land in also used for fish culture purpos~s. WateT is Jet into thc,se areas tide through llluice gates and th.o infiowing water brings in fishes Fishing i~ge'nc,taUy done in winter mon hs ufter aJlowjn.~ for stowUt inside. Thus, cutU.lre for a few months i involved SPECIES AND THEIR BIOLOGY .~ .• "~'~II water ouJture of praWns, the species iIivolved are repre-groups of Decapod Cr'llstace-a~ namely tbe marine pf<\-wn ~'l'c~nac~jd~Le and tbe river prawns of the Caridean family Palae-rule, most of he: cOlllmercially impjntant. marine penaeid Iolilsociated with brackish. hallow wnter .env· -Ol1D1ellt-, each- with a different alld somewbat restricted geogra~ alOliS the, coa$tUne of India support important coastaJ important a,mong these are Metapellaeus dobso1Jl. M. af!in;J. r~nwnlr1ce,os. Pell€t·eus indicus, P. monodon, P. merguiensis, and P. sctJptllts. In the context Qf ~r4cJci . b water inter.BU tha:ttlte~c p.rawn have a distiuct life hi tory of morc or les!i pre:dicta~te length of timepeot:ill b,ackish WB,tC( environment. In each of theBe peeLs breeds in the sea at varying distances from tbe shore of microscopjc, s~mi .. buoyant eggs reJeased hatch oui 116 ~1. J. GEORGE AND K. H. MOHAMED into mall planktonic IlQuplii. Th.flse larvae pas through diili tent IllgcS during their tnQvements towards the inner roaches bf Qackwat.ers, The lim~ laken b tween hatching and entry of tbe smail posHarval prawn into the bad(Wat~rs -of estuaries vary whh species. Opcc inside the brackish waters post-larvae s~ttle to the bottom-and quickly transform into ju leniles. enter tile paddy fields and siruila-c low·lyiog are~s 'n these stages and co La tbe fishery mentioned eadier. Species of Palaemol)ld prawns~ in which he females carry Lhetr underneath the abdom-en externaUy -and the young ones hatch out at a paratiely advanced stage of developm-eJ-lt, are of somewhat lesser imp commerciaI1y. A-couple of pecies of- the genus Macrobrachium (M, hergli and M. malcolm.~otlii) canui-bate 10 commercial fishery in the var river y tems of tlle country. Some a p~ts of the fishery and bi these spc:cie have been studied by Ibr.ahim (1966) Raman (1964. 1965) Rao (1965 1967). Ling (1962) has worked out the compt~te life-hi M. roscnbergii and it is obsen'ed tluH a cettail1 anlollut of salinity i for the spawning of the species and the growth of the early larval lages adult malure prawn are (hus- found to descend fro,m the upper reache riv·ers to brackish region-s of river mouths for spawning. After tbe mellt.- of the eady stages in this envirollment the young ones gain back to the . fre-shwater areas of the rivers, Tlle la~ge '1zes attpined by ptawn especially in the ca e of M, rosenbergii (growing to :nearly in. length) make it particularly desirable for artificial cLlltivation. BRACKISH WATERS AS HABITAT OF PRAWNS Tbe toie play~d b)' the brackis-h water are<J,S in tile life history prpwlls h~s lo be u.ndetstood properly, ThepeuaeiC:t prawn. of "''''.uu"". in and out of the e-st1)aries in lbe manner describ"'d ea.rlier sinl-P'" they areev.olvcd that way. Il is known when and where the occur and 'it · also possible to dc-scribe thei-r surr:oundings. But tn UU~ fU/lotio.nal role r the highly dyn-amic environment in whicili dudng tbe j<lvcnile pbase of their life history, we fall far short br The Ill:.ljor [actors regulating the ocrnn -n e and development of (he praW)lS in the ~stuarlne -em'ironment ate water circulation oau~ and currents temperature. salinity and other chemical propertie • terWity, \'egetfltionand Ilajure of substratum. It must be all the abov~ factors play complex and infetaetiYe- roles in distributio"" survival and growth of young prawns during thejr the-estuaries. The mechaniQs involved and the extent to whic:;h -factors influence the productive-ness of commercial prawn b~ funy elucidated. The -arum;\l life found -in these environments is geoeraHy wide rat]~e of ac taptability Co withstan4 extreme fluctuation in tions. P~tnikkar (1951) stu died the regul&tory capacity and adaptations in an estuarine marine fauna including penae'd BRACKISH WATER AREAS FOR PRAWN CULTURE 117 b.y Rao (1958), Williams (1960), Dobkin and Manning (1964) and Zein-Eldil~ and Aldrich (1965) impart considerable understanding as to how prawns st physiologically to the varying environment. Although these observa-s partly answer the questions of why and how these organisms satisfactorily with their dynamic environment, it is stilI not clear as to what degree these changes affect the magnitude of their stock. Among others, Menon expressed apprehension about the possible detrimental effects of the of the brackish water environment such as reclamation for agricul-port and dock operations, construction of spillways in the furtherence water exclusion schemes and other engineering activities on the prawn s. It is highly problematical whether the estuary-dependent marine of commerce can adjust to the environmental changes and consequent tion in the various factors and still maintain their stocks at the present Our knowledge of the biology and dynamics of the prawn resources to the various environments is slowly being enhanced by various . But much remains to be accomplished before· we could muster the rmation by which we can defend the inadvisability of modifications rtant coastal bays, swamps and such other brackish areas. However, approach is highly essential in planning all the projects entailing nt of the brackish water areas vitally important for the prawn RESULTS OF THE EXPERIMENTS CONDUCTED with the importance of the paddy field prawn fishery of Kerala of th~ marine trawl fishery of thee-Tea. tbe Central Marino Fi"heries Inst itllt~ has heen carrying o'ut experimentfi to swdy he variou aspects' and Ihe nature of prawn farming invoJv d. Menon (19;54) studied 9f Juveni le prawn of Perlaeus inai us stoc ed in mall cornpar1-.Cullured fo r l pedod oftwo months and reported substantial growth , than what Was l.ibsetVod in the ' sam,e sptli:ies fl'om. tho bllckwaters As a rc nIt of ,experiments cOfiducted by h im in a two-acre farJn used for rice culti!fation. he ooncluded lhat approximately 36'0 prawns eotlld be prod.uced antl~ally from such fields , According deveteped in s'l.1ch ooa tal tracts witb faci )itie .or takitlg in ~ction frO:m 1)ackw",ters and canals couJd be expected to yield and LjSOQ Ib (0" 450 tp (i8{) kg) of valuable food per act(l all.nu· fisb obtained along with prawns. Receni e)(perimems carried Q/. 19'68} to detetmine whether culture methods could be aMant-into tho axisting prawn filtration pracrices in rhe paddy the backwat ts' of~rBJa -showed tl1a·t oultudng of juveniJe perllillfs: ll:t1d fishing llem at inter al~ of about a 'Il'IQ.,.th jll8tead 'Prlts:twc or· COl'tnighl1y fish ing r~:'i l,l lted i:n relatively better prawn " of the river pr.awn lr!{1t1ro.f)rocl!ium r(J~'enfJertli. Ling (19!i2) breediog tb~m in the la boratory, Bu be did not fQU~w it ul? b;r us M. J. GEORGE. AND K. Y. MOJUMED -introducing and culturing t!Ie labora.tory reared young ories in natural ponet . Ram.an (19Q4) succeeded in locating a ilursery area in the Pampa river system from wnw: youn-g prawns could be coJ/ected in large numbers for stock'ng and rearing. A f,UID for the culture of the .pedes is already in the initial stage of it operation at Edathua ill Kerala, Tbe pre ence of -young ones of this species in l::u'ge numbers in the HoogMy estuary ha b~en ,reported by Rao ((9<55). Ibral1im (196~) indicated the possibility of cu.lhlCiog the rel,a .ively Sll1aUcr prawn PJ. malcolmsOfl:ii by properly tapping the source of the upstreanl mov11lg juvenile {)ver th £~sl anicut oJ the river Godavari., It is found tbat along tho coastline or India this specie occurs only in some, river ystem tno tty in northern region. The possibili ly or !rIui.splantlng. tbe species to in the south should be seriously examined. PROSPECTS OF DEVELOPMENT In ()rder to increa$e lh production of prawns in the practice. utiliziht brackish water areas th~ foHoWing considered: The-method of paddy field prawn filUarOD oouJd be .adViln .. """,, ... introduced in similar estuarine and backw.ater areas along the ent1r.e of India. Already such fiBhing bas been introduced with encQul'aging in somc estuaries alaogthe Malabar and Mysore coasts. The method ' introduced Itt Kagal in the Aghanashini estuary ncaf Karwar ha.s sbown imilar methods CQuld be introduced in 0 her cfil,Hirinc arc-as too. There are extensive swamp areas and brackish wat'el' pools with rhe various rivers and lakes along (he coast1inc: of tbe country paddy ~u l tiva t ion and prawn filtration practied in Kerala oannot be as such. These area 'could be C-DDVerfed into brackish water ponds by tructIon of proper dikes and provision of sluice with sliding hulte.c . to \.I lsto inflow and outfiow of tidal Waters . Rao (1949) e' rimated aco t of Rs per squate il1i1e for preparing nch farms. Accordins 'to him, 'ifat fe«sia ·of the area of the coastal salt wator .pools or ponds is ujtab1y made available for fish cultUre, the Cost would wor1c out to balf a rupee: ' . Thi-s estimate will, no doubt. l'c"luire reass~sgment under the conditions. A significant yield of prawns io addition to otberfi bes be expooted fmm these sources. Salt marshes, hallow lagoons and many swamps should bl! con prawIiponds byexcl1vation .and diking. In. Japan abandoned solaN It b,cen converted intp modern prawn-rearing ponds where the known as ukuruma biimp' is sltc'cessfuUy cult ivated (FUjiD4ga critical p roblem of obtaining a steady supply of seed prawn is case by most highly developed metllods of prawn cn'tuTC. }fere are reared fcom egg to au ult stage under closely control1od Similar methods. hawd be tried wHh the Indian pedes and suifab' techniques e-volved for a steady supply of seed praWns. In the existing I'a,ddy field prawn filtration JJl~thod of the BRACKISH WATER AREAS FOR PRAWN CULTURE' 119 areas of Kerala, a method of trapping-cum-culture practice is recommended in Qllder to increase the catch as well as the size of prawns . Fishing at intervals , f about a month has been proved to result in increased catches and also larger sizes of prawns. In the paddy field prawn filtration practices at present, the supply of fry is entirely dependent on the tidal water flowing into the field from the aters. The stocking of the field is only accomplished by letting in water the fields at high tides. It is felt that this could be amplified by collection larvae from the out side waters and stocking in the fields as is done in of the Far East countries like the Philippines and Formosa. :rhe possibility of culturing the river prawns M. rosenbergii and sonii in ponds should be explored. Transplantaion of Macrobra-. to river systems where they do not occur at present is another be considered, for example, M. rosenbergii is at present not found to the northern river system emptying into Cochin backwaters, while common in the southern rivers flowing into the same backwaters. M. malcolmsonii is not found in the river systems in the southern lantation in these cases could be tried with advantage. hese developments envisaged would require accurate data on the in order to make realistic plans. Here the need for properly res :1rch mU t be ompha ised. REFERENCES and MOfl'l'Iin:i. R. D, (1964). Osmoregulation in two species of Palaemonetes : Deeapoll:t) (rom Florida. Bull. mar, Sci. Gulf Caribb. 14,149-157. (1963). Culture or Kuruma shrimp (.P(m(J.t!~$ japcllicus). l.l1d.o~PtJcil. Fish. Aff. Bull .. No 36, UHJ. . Moll$.R1ed. X . H., and. Neelal<lInt:M PHlaJ, N. (BiG'1). Ob~c1VatlOli5 D.Q th~ prAwn filtmt~on of Kcrala. lIuill, PAO Fish, Rep. (j7), YoJ, 2, 42742-19 S). Prawn culrure in the ric-a .fields of Tnlvancore-CoO,bi.ll, India" ~"'I"""/I Fish. Coun., IS, 419425. N.ai'r, K . K . (1944). SllggeSUolls for development of salt water ba<lha O. borlC;li .hl the SUnderbliliS. .Ftlhery Dep. P'ampldl!l No, I, <!rm.()/ We·' Dr/lial. Cafcrma. 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GEORGE AND K. H. MOHAMED Rao, H. S. (1949). Research in nsn ta'y cuiTSet"'v'"1l1ron h'~chn!qM!I us,ed i ll tudyjng fisheries; the integration of hydrological and biological and other studies in a well rounded marine fisheries research programme in India). United Nations Econ. Soc. Coun. E/Conf. 7/Sec/W.120, (Wildlife. 6 (a)/4), 3-9. Rao, K. P. (1958). Oxygen consumption as a function of size and salinity !n Metapenaeus monoceros Fabr. from the marine and brackish water environments. J. expo BioI., aEi.-307-1.3. !l!t()l It. M. (196$). Breeditls be,haviOlIr in Ma~robracJtfmir ras!!IIi;.et:gii {de' M.an,}. T!ls1j(~ y Tech.. 2, 12-25 . - ---(1967). Studies on the biology of M acrobrachiu1l1 rosenbergii (de Man) of the Hooghly estuary with notes on its fishery. Adv. Abst. Contr. Fish. Aquat. Sci. India, 1, 18. Wi!Iia rns , A. B. (1960). The influence of temperature on osmotic regulation in two species of" estuarine shrimps (P·e'llaeus-) . JJloi . B tli/. , 129, 56.0.-'71. Zein-eldin, Z. 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Utilization of brackish water areas for prawn culture

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Utilization of brackish water areas for prawn culture

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