PROJECT: A.I.D. csd-2780 INTERNATIONAL CENTER FOR AQUACULTURE RESEARCH AND DEVELOPMENT SERIES NO. 4 MARCH 1973 ARTIFICIAL SPA WNING of MULLET CULTURE of MULLET and MILKFISH in TAIWAN International Center for Aquaculture Agricultural Experiment Station AUBURN UNIVERSITY R.Dni Rouse Dreco uun lbm and Auburn, Alabama R. Dennis Rouse, Director COVER PHOTOGRAPH. Traditional method in Taiwan of stack- ing milkfish in baskets prior to marketing. ARTIFICIAL SPAWNING of MULLET and CULTURE of MULLET and MILKFISH in TAIWAN H. R. SCHMITTOU' INTRODUCTION TAIWAN is advanced in various aquacultures. Its fish farm- ers are especially noted for their cultures of milkfish in brack- ish water and poly-cultures of Chinese carps in fresh water. Its research biologists have been among the leaders in de- veloping shrimp culture and have been the most successful in artificially reproducing and raising mullet to food size. Aquacultural facilities were toured in Taiwan during June 1971. The itinerary was developed by Mr. T. P. Chen, Director, Fisheries Division, Joint Commission on Rural Re- construction. Mr. Chang-Jyi Chiou served as interpreter. This report includes a summary on milkfish culture and the techniques used in artificially spawning and raising mul- let in Taiwan. CULTURE OF MULLET The discussions of milkfish and mullet cultures were derived from observations and conversations with researchers and farmners in the field and from published literature. Aquacultural potentials for milkfish and mullet are greater than those for most species. Both are hardy and respond well to management in confined environments. Both tolerate adverse conditions; the mullet tolerates colder temperatures, but the milkfish can live at much higher temperatures and salinities. Both have excellent consumer acceptance in the areas where cultured. Both are herbivorous, feeding primarily on benthic and planktonic organisms that can be cheaply produced. In Taiwan no farms were visited where mullet was actually being cultured. Dr. I. C. Liao and his staff of Tungkang Marine Laboratory, who were the first to successfully spawn mullet and raise the fry to fingerling size, were interviewed. The techniques used in the artificial spawning and raising of fingerling mullet are summarized in this report. Very little is presented on mullet culture. The striped mullet (Mugil cephalus Linnaeus) inhabits marine, brackish, and fresh waters of such diverse locations as India, Taiwan, Japan, United States, Israel, and the Soviet Union. It is a valued food fish in most of those areas. The adaptability of mullet to varied environments, as well as its food habits, hardiness, market value, and other characteristics make it a popular pond fish in Taiwan. 'Assistant Professor, Dept. of Fisheries and Allied Agricultures; serving as Chief of Party, AU-Government of Philippines Inland Fisheries Project, Manila. In total production and value for all Taiwan aquacultures, mullet ranks third (2,200 metric tons and NT $44 million2'), milkfish first (19,000 metric tons and NT $400 million), and oysters second (12,000 metric tons and NT $121 million). Mullet spawn at sea. It is believed that spawning occurs in the offshore waters of southern Taiwan. It is known that schools of mullet migrate southward into the Kuroshio Cur- rent from November to February. The peak of the migration is in late December and early January. Fish taken during the migrations have mature sperm and almost mature ova. The migrating fish are 4 to 5 years old with body lengths averaging 42 to 45 centimeters. Fingerlings 2.5 to 3.5 centimeters long are collected from estuaries and coastal waters along the western coast from December to March. Usually the mullet are stocked in fresh- water ponds at 2,000 to 3,000/hectare in combination with the Chinese carps. Annual yields of mullet/hectare range up to 150 kilograms without fertilization, 400 kilograms with fertilization, and 1,500 kilograms with feeding. Striped mullet can tolerate water temperature extremes from 40 to 350 C, but the optimum water temperature for growth is about 230 C. Salinities of 0.1 to 38 p.p.t. are tol- erated by adults. Young fry will not tolerate salinities below 17 p.p.t. The annual demand in Taiwan for stocking ponds is for about 7 million mullet fingerlings. Some years the demand is not met. For this and other reasons, research was begun to artificially spawn and raise mullet for stocking size. This work began in 1963, and involved the cooperative efforts of the Taiwan Fisheries Bureau, the Taiwan Fisheries Re- search Institute (TFRI), and the Institute of Fishery Biology, National Taiwan University. Their early work on induced spawning resulted in producing fry, but no fry survival. In 1967 one fry out of millions hatched survived for 23 days. The work was transferred to the newly constructed Tung- kang Marine Laboratory of the TFRI in 1968 where the work was supported primarily by the Rockefeller Foundation. That year, 2 fingerlings (1.0 and 1.1 centimeters in size) were kept alive for 30 days. The following year a total of 431 fingerlings that ranged in size up to 28 centimeters and 217 grams 200 days after hatching survived. In 1970 approximately 50,000 fry reached a length of I centimeter (27 days). The techniques and procedures for artificially spawning and raising mullet to fingerlings were as follows (Dr. I. C. Liao, Director, Tungkang Marine Laboratory): 2 NT (New Taiwan) $40.00 - $1.00 U.S. wa'dx\ iiir ltoc kitw fgit 1)1 ((11 hl potids itt 40) to 1.5 tlax , It It li/i'- (It itttt 1 hc cuittu'., if n ul, tI. is t icr.> Cl S''' y poputUO - I t SI O. since successful methods of producing fry in hatcheries have been developed. 1t.i t o o e I.lu \ w i r t il ,i~ m i \ ,( xx od r .ix~c loi tlxiiit it'dil ONiil ~ ltI tiot o ililt'. t~tt tsiiit. boilt il 225 tt245 .1I :31) piti hags 2.5 I). .If itxtiol of . 75t let xxa pldi ii t'tlititr id x lit' .lid lititi 2i ito 50i xx l it too it' (1 li i ot 15th lixb l \tit i i i altititi of g: iii itt \\i 1 pit d x(iii l6 tix xx c ix t ) it ott per)1 ill. xa t iI t tttut~/i I It'll S ttcll Lailt '.'it~ ui ('ii11i)) \oItlit), ]loll i Im ill itt ol Ithr. .31) it. Ix) ctit'.t it~t (1'-( 2 ]if-. :M) itto. 3l)1 clc'ax .1 50 iiii 5thtI') it i tt 1(1 Ili. 3)) toul. 172 lii. I)) iio. :3:3 lit. -10 ttu. -IS ]itt. 5(0 Ii. 5-4 hri- .59 hr. otiit 111)1 icl i til-it pli (Ai I lxiti \(ids bitt' Ti lott po x otil x]i it I Ik it ' (f e Tod ill1 i'tiiit t plitiig rl toftli 3 1) tint. CULTURE OF MILKFISH 'I'lic millsfi.di Chaito.s Owno.o ulthowd, cultilw(I ilifilost ('x(dosivel ill Tai\\ilo, lodom'sul, lod thc I'llfilippilws, i's t1w [)lost jillpoltiolit filillille imd bliwki'sh \\ilter species (.111tilled ill t1w \\oild its till it,, totid plodlictioll is m1wellwd. It i's h L11. tit(, Illo'st importimt spe('ies of fish (.111tilled ill 'ktj\ tllj hoill tit(, still Idpoil its of lood prodlwed alld ( (.ol loll) ics. The producti0ii fit 1969 of I,),tY)5 nwtri(, toos of millsfish \irs 'Iwiltcl thitil lot itll\ other sill(de Specu.s. It \\it's 33 per (.cot of the totill Titi\\all ityliwoltoial piodtichoo of 51,064 nieti-k- t (; i is \ I () i i c t i i i .\ \ i i i i c o I t I i (, I '), W )5 i i i ( t i i c t o i i s \\ i t s 1) i t (-(,( I ;it VV 395.5 millioij of aboot 4:3 lwi (-(,fit of flit, totid idlic of ilquilcultillal plocllwtioll. laiwill(t froill 20 to 2) .5 C is xttttttiz it,l foilo\x x. CoIll iticlit S Basket of mnlktish is weighed prior to sate. This is the most im- portant fish species cultured in Taiwan with approximately 19,000 metric tons, with a market value of NT $ 395.5 million (about $9.9 million U.S.), produced from ponds during 1969. Commercial Harvest Caitchfex of aduilt miilkfixi oii the hligh xeax iiaxe l it liceli 1 epic tici. liepoi tx ii e collinon of ii ioctaionial catch uucaul xihire. Sciioolx oh liai ge fixih hiaxe e ci obisietie offhoreii xx itii thir doioux fixs aitoxc xx .itcr, a chiaracteisxtic iif inlilk-fixi. itau ge fixsi hiaxve iieeiu taught 1lix ioiig iii hex aiidl ti axx ix opcu at- ing fr om iiairborx iii Taixxani. \iilkfixiu iuax asiio bieei takeiu xxithi stake tirapx, liftiitxt, xcincxs liaipiiiiix aiit cxcii tex ploxixvcx. I Iiix cxc, the catching ot iiilkhxih lby nueaiux otihei thanl hIn pouliuiig isuccidci tai iiid tihere ix lin conlilieitiai uperatitoi lotiiiiiarx ctiiig uuituial xtockx ol ,diilt iikfixiu. Biological Information Dismtrilmutioui. \hilktfixl i( t(lisxti rilitethroluiugiiuot tue( tiropi- cal ilil xiiiti opicaui xxateu x of the I uutiau i aiit Palcihe Oceaux. hx iti it foiuiit inl the Atlanitic Ocean. Life Historx I. tr x littli is kiiiixxr ii olluccinig thje life hiixtiii of iiiklixi. Spaix nog ottiui x froiii Apuril to Augt xxith i peaik iii late Apil (iad i Ix ,i y a. 'I'lex \; ax SIii ohff' xhleIiiti i i, rehatixe ci sliitliixx xx atiixxih thiere il- e xiidx Mi cou ail biittoiii deixoith oh x egetathi iio xxd licic xiiiiitx ix 32 to :3:3 p.pi.t. Sexiual inatiiritx ix thought to lie a ilciibut i elx of age. Thle xilillicxt id1 lilet, gei gi x 1 (1 iiiiie ix cl l it Oi dt w i e 94 miid 124 t'eiitjiieteis x kibiiit 9 aiiic 12 k.iogiiiis), rexpecti x clx. 1Recorde (1cc i giitx oif oxvaries' ot ax 1(1i fish liax eI ranged1 hoi 0dit.5 to l.5 kilogramsiii. Estimaitedl Tuiinlei of eggs ridl frini :3 to) 71.3 ioillioit feiiiale. iTie high feniditx suggests loNx xiii-xix al to sxiii iidtiii lit\ 'The eggsx are pelagic dud aitit 1.1 to 1.2 mililiiieteis iii (ldimeter . Thie- hatch iii aiboit 12 houirs. The 1\ ai :3 iiiilli- iiitersx at liatclioiii .5 miilliimeteirs at thriee daxx: iid abouit li0 iillimeiters x lei i It) dav old. lihe fix touind alilr tlie d\inIx wi,Ilics ainid estuaijes ate 10) to 1:3 tlas ilil-od din nhi iiiiiii of It) millimeters inl length. Fix atre dlxx ax x miii id iii cledtr xx atei oxe i xi lxk lint toiii tliex (lit Hecic foiil iii siltied xxittei or iii iix l boiii~ fittiomsi. Feeding Habnits. Asx frx, iijlkhxli feedi oii ph)litooi iid microoi c iixii l d sxiriall iiidcroixeic hieiitli( in giiiii. Did- toii aie iapai ii t I their piriimaiy food soiiiee. I' edii g habiits of the idultx cliiie xcix little friti that of the Irv. Ill thieir iltoial Ilailit, Ililkfixh iti- b eliexved to hie piiiiriilx licntliixseciiixiiiiei fee-diog ii diatoiiii .ii c blie-ri ci .ilgitc. Aiiial oiiii coiinuiiet aire consiideired to lie iliietil iiiiitiirex to the xcetittixe diet. loxx cxci, suchi irgaliiiii itx horiioiifera, Limiellili chiati, Gaxsti ipoda., (opep)(Li., liirxal liiix ex, and egg. of fishi aire found1( ill digextixve tiraitx of iiiilkfixli. AXlxo Iiiild iare ililnei l piartit'cs(liii itiix, alit 1 traginciitx of iiiulticellnlai x cgtitiii. \axenliti pliitx .iiid cectitii filiineiitotix algate are appai citlx takeii oilx~ afifite pinis liax, e gii toi decax \. -\lilkfixhi appi iialx feed, inl ior(der of pireicreice, oil organixcux oii the Irnttoiii. ill tile Ilij- xx itei . ild oili the xililate. It ix ircpiited that milkfixh icr tiiii ivi audi si tagex cd ix(elixclx diii-iog the dta\ time. Enxvironmnixtal Tlolerance. \iikfjish liaxe niuxuidi tohei- ice loii xx ide( fiiuctuiatiou u ill the ci x irooiieit, n((i ioi moe timi most inn ine aoiinuiuix. iliex ie repo tid to tolci ate ituges of xiiuiitx froint 0.1 to It) pii~t. TIhe\ call lix e' inl xx aterillp to 40) ( hoxxecxri thex become xhwggixh atl ternl [clilctiurex beioxx 20) (C. Snddu driopsi ill teiiij ili till i cxiitix e beeui knidixwn to cauxe dlixcoiihuatiiiu i tempiorary d ix ldlieiicxx io xiiethhig of xkiii lax cix. Fry Collection and Marketing 'File tiliectioii dtti iuauketiiug of muilkfixli frlit ha tockiiig iiuti ponitxds ar xpecial phaxes iif the unilkhxli taiiii iii- ixtix. Co llect ion ofi Frv. Tihi Iirx are i ecexxaiii x collecte frntoi coaxtal xx\\atiirx xince artificiai illealis of xjixx hug niilkfixh l u xet to he dexveiopei. The fix aire coliectetd diii-lug the iotix of Apili to Octoiri xx ith at peak seaxol iii \1,1x and jiii i. (:ollctiu g groodx are the xiii id xiiaiioxx aretax atlong the xsiiiti ibeaciex of tue xoiutiirit hail of the coiitiN Sciop iiets are emplox t't liii eoiiicttilig iliSIlx flxr ueai tue Tiiugkiug \iaiinc Liii attiu x, xxhere aiioiit 21) coilctourx xx(rk. Thi scii p xii 1 et x arc Consixt rucid i(t of b lxi polesc ii d cuiars xclothi. Each ix ci in ti n teti lby toiiiig the poIlex iiito iii .Xsiaped fitnie id attacluiiig ftle cioti to' foil ii ibag ill oue-iiall of the X framie. 'Fie otheri haii ot the Li anli xerxe xs axnailiex. Thet ti iaigiali scioop s appriitex 2 minti xwxide itl tue hixse iid i2 metersx deep. The iietx aire piwt 1ioiig xxxi'ill jiiixx" S aitIhxI k ii ta iii xx alci inkle-dieep to xiciuldicr tieep. tatli net ix fisihedi foii i1t to i5 ioitex iiefoi the ciat isrineii d. is ixi xitlji the ucet are iai xextet ii\ gathci ii1d the li ctting hintoi a niail bag of' aiiotit 2-iiteu x tiunie xxiiiie xiiuituuuouxix liitilg ftc "'tli C ittiit llc t ' h u o t iliiiith e i catc ill t h I t eitit ti w Ifftt 1.3i lic(,I ito si r t o lt'!ti . Nlilixi ed t i x litiel xt i] I( )Xt' it 1 ii 4te \ tit \ of t-o I it' u'i i iii t i t!l l li i t~ u to h 'it' itiit o t hei(' ~ e eotitiix iu t~if'j'iift] iiil e ItII]\xoi tili .ix f'i ofi I ficr ci del fu it cxix ~ifii sp~ i xlit fl i f oot t0 to 1:3' filfliters tttl etth . ifit' cif' i \ ito d pos i t 2 tfi)l~ix( ittlatfx o ld it )(, ttjiftx. 1 3t'x t o.tfu' ttitt'jti xxj tf lci t I soitx xfito sce ' m ittl itictihit ix ;t~ tillt iii bl owxxax t ltt it'sit suc it h 'rx appears t e t'tlt'e ii xt'ile tth tit'.itt xfptt'iltifg l/li 4 ii (,its1 i\ ivq ii tls abo t' i m iitcsi itkcif ifi h it'w lishrit Cii Ii I'( .itiIf S t t'titiiit'tt' A If'') fhis at'f cx it l Iiff I x ji t c i i it t i dp tihe i (idtl itt hili \ e ii tbou t x00 1 -\i ll iit . flit lix (it'c pe ('ftxxitt te ii. oxi t ~ il .the ii c l itix i xItio l ffiitt se s l . i 1 i C' ilfii r i cct .ittit 'f iS1 s St% f\it ) oi flu fix. 'fI(, ltxd oftfi hii iiiid) f tiies i t iit ix ei itit \%if Stilt( h(f ift fix ott te ti s ift i i ftix x),% ixjt ll.it flso ietti k t'ttCf i i tfit'ttitix lidt \iw ilfa liIcdxi itot tfx 'Nf oi ft iifif ireti SII iti stiimit t be i tte tilfli f 1 oili it ix ofii t ii i lst~. ~ti iitim hlc \ t ish aii ei I. titti iiiilki ujxf ititx to it' lti i fillt'C illt Ift' jtarxi o fi ibou t idife s xIl fITi t tre ttiflitd Mxid Sii TI titl itt' ideef.tj t Hittil \itf hlds it houpit ptiio tippi i tfix i l ililt 3 0 0 Ifit jill itx. 1 it \ at ii fi'I fftt itre Iedt\lti(( ii lie \6i0tx cc li~ li o f :32 oft i. e \Itfk fjxi .i'C'iit i\ it iti it\ e iii t i l the iix t il 711 fi il. H c t fi t 'atx x t'uxiii tu '1 och ' iTittex cli ititii 3 ii 5 ii' h l te iijf 'ttd i ta~.fiti Cif).3 I Itit-i tit i t elo _, ('f it idt' ittli iti ixa rit 1 I '. No\ItIkjIi filhi x0 i x ttxjf il f a to xit tic 1 t i t (m iit c'litti lid ithil cii ixii ti I te t' x ir iT i tt it iii the it fiifix iii to . xitt h .to ti o fi' b ilx iiti xx ith i ti l xxiill itix i i h h it~ 2i till if it't iikftax Workers are constructing a framework of bamboo poles over which is placed a layer of rice straw. When completed, this structure provides an effective windbreak and reduces fish mor- tality in wintering ponds. Sttic'kiii Nui'ser'x Ponds. ish lioii ttt x l'ki te it'xx Mlanagemnent of Production Ponds. Niilkfliih colii IliX Pastorii is ill( t he li foi ('ficil'it pr0(Iic'ti(Iii of 1both. Th e pasturei lotiij m tillll is tecliifi2 pol cIlh s co lixtio plilii o I le- 1 )ie'p l ati(ilio h diatiiicl i ii) ul xlllXelpci i (-il- ider t4iox be ( xl'l prll 1'iiix lil to b,1 c~li toductonei litii (dfiite1 \ 10 stit d xiil I c il('i( are isd dI th fiil e rsi till'roducel lil tuli lil c l llox il'l~i the o ll t iIs (\ lt 'l()ctoe 1.5 io Poficix pond otttom aiti fiobsaequiilit x iTc ill,' (1 th'patur z ire pro iaie dl to fi 1i ll mo t il- (i illke dllitl glitex I i'iiihci I1to Icill I i IIli I I is I 2 I V xiiit Ii cI xlto bel Tlffe ~ ooi Ixli(4its itreimto l\ o toxxie I ot cii di h' 121)1( i lit1ii~ tac t(f Tii e sietcrops . (, pei ic ickx de ill(-sanl poo it i c ill ol' lix lp l t ie clixl lto (lciciix e Aproimtidteio ci tcx oiii ateo re i 4tue 12(111(1ci Octbe 1 illds l ]eud to1, (ITlli% iateihs iare thatli e ii Nmellibeti I l xceii ~ite t ix tcrin cx id(1 ite piex i'i'iiu ~ cal liv diix I cue4ssll i~t' i t 1ucY repix s i tic i i cliic ocii (likeil gl ti x e dx i'l csi' li(itxii \o\(,m(lx 15 P ti e b ottiu tor ri lept"illof aoiti tt ciiped oni lica(illt tiliilel tle cxrlidi iteldi Niai cii 7 VIt at i cic 1 iiiixieci'ae tO o izi 1 decii xxof 1 ill 1 lill( -it \~a olx itc' .r 1 occur xs. itc Decmbe I ci iiiis' floote (((11/ll) xccih e a t to i d th' o abut k. u 1 . Cc' ll the'liteix i p it ix liX\ ti r 01pixiloil ei tiiii C pxxlot Neill li21 I lOric ni txtciils u ix s i ic e tt hiot chillgl I i 1.5e ctrm 1rss i icx ra Il to el i (lii siX l, Mid i (~iciol TI m 1(1 ferilier Itc' tpica (cti i i c' p 1 IX boi~i cll; c'xc't i ilii l c'filo te ' iic iait ail c o p tt tu 121 olacx ilx Xclp ll Mil-ctIii,1c fiuxtilc'iifloo1IiC pciii I 'i repea1i.ted.' xxei prc'litaixxclloi o\ilukc depth ilc Inil arch 1i 5 Aiiotic' i liitictio o l tc'iiisc'i ix pox ' Nfitix I N I lx 15 11111c 1.5 %% it I I 1it(ltili I o)1 'sl', %% Acr t he I Il( ' o11II ix-\ xxllicli ,ir I to 4 ciii. ill siz'e ilc stockecd its (,i t iilc o'I 1 Irol l u-cr 1111Xi X ll ills alld ll(,li ((II (4 ofle it' 11 fish. Th1 ese fishi xiii lbe the (o ii lll] cio prdue P )li''liill l sciio. Alii apJpliciiti(;ll of leitilizei ix iid' it I l('(lf((l. I icl Ih Ii I d i Id1 last stock iti I i mai t x i :1.500 fix- hit, Thes~'e ix- aiel ixo x oii( i the-_\ c('dl fishxlid iit'e stocked 'l i) te iou11 seix\ Thlese fishi \viii be lxiiX (stedil i Octo- teim 4 1 2olds. iiiic :3tt 'fil hxt li ,s 't ix 112,ic xxlicli colliitx, of tiic hxii xtickc'c iii NMatcli. Sepitemblelr 1.5 1 llic sc'cond cl u, 1 x('t ix llli xx iicii cioniitxs of' tiic fish istoucked( iii Apili. Ocoer1-- tondkis (4, i tieiix ii il t11itb lxx fishitli stiiig (4 e trkisere toiii.er6it Iflli' estilill Nhikii ic clil ixsh it( Ii fi lull ill', 1 2ii (Yel- il i tthccr iixe'xx the fiixt ii Jiuie: thelc' oo x'(iill iSe'p- 2.5ff (4itiii pei fxsi. Gill iietx if ioiilohliil('cit Illexil a1re Ilixl. NMesh xize is suchjl thiat iiiio i1 makctt,i' hxii iti takikci. The( WC'iill iiil'xct ix ill %e 1 te1'ibl' xxil 1 till fixii xtlck'ci 1,8til to 2,00 kilioirams (41 iX 111( seaixoi I. \evr I ~X 'l ill', Bfureaiu lixtedi i 6,298 i li c iii iiiiiikhxii 12111(llitiiii andl Milkfish pond being harvested by fishermen with gill nets, Size of net mesh permits fish that are below marketable size to pass through. Survival of Different Sizes of Milkfish. Survival of milk- fish is apparently very good although the fish appear to be fragile. Disease and parasites are considered incidental by both the farmers and the technical people. They consider mortality to be due primarily to predation and mechanical causes. The following is the expected mortality for different sizes of fish under specific conditions: Mortality Fish size and conditions 1 to 2 per cent----. Fry transported from collecting grounds to market and then from market to nursery. 20 per cent------ Fry of 10 mm. to harvest size of 150 g. in production ponds. 2 per cent------- Fingerlings of 12 to 15 cm. to harvest size of 250 g. in production ponds. 2 per cent------ Fingerlings of 12 to 15 cm. in overwinter- ing ponds. ITINERARY June 2, 1971 Arrived Taipei, Taiwan June 3 Joint Commission on Rural Reconstruction (JCRR) Taoyuan Fish Propagation Admin- istration June 4 JCRR June 7-- Chupei Fish Culture Station June 8 Tsengwen Tidal Land Milkfish Farms Markets for milkfish fry Privately owned freshwater fish farms June 9 Washan Tou Fish Hatchery Markets for milkfish fry June 10 - Tungkang Marine Laboratory June 11 JCRR Departed Taipei, Taiwan