Proiect: A.I.D. csd-2780 INTERNATIONAL CENTER FOR AQUACULTURE
RESEARCH AND DEVELOPMENT SERIES NO 5
MARCH 1973
AQUACULTURAL SURVEY
IN JAPAN
International Center for Aquaculture
Agricultural Experiment Station
AUBURN UNIVERSITY
R. Dennis Rouse, Director Auburn, Alabama
P )-"."L
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sow p

AQUACULTURAL 
SURVEY IN JAPAN
H. R. SCHMITTOU
1
INTRODUCTION
JAPAN has made important contributions to the field 
of aqua-
culture and has led the world in developing 
cultures of
marine and brackishwater organisms. The 
country is limited
in areas suitable for inland aquaculture, but its vast 
areas of
protected shores, bays, and inland seas 
give it high potential
for culturing marine and brackishwater animals 
and plants.
Japan has taken good advantage of its potential 
for both
inland and coastal aquaculture, especially for 
the latter. Ex-
amples are development of cultures 
for seaweeds, shrimp,
oysters and other molluscs, eels, ayu, 
trout, and yellowtail.
Last year Japanese research biologists were 
the first to arti-
ficially spawn and hatch yellowfin tuna. 
They have also
collected fingerlings of yellowfin and bluefin 
tuna from the
sea and raised them in net cages. In 
support of its aquacul-
tural developments, Japan has many well-trained 
biologists
and some of the best-equipped research stations 
and institutes
in the world.
In May 1971, the author was able to tour various 
Japanese
aquacultural facilities. The itinerary was 
developed by Dr.
Clinton E. Atkinson, Fisheries Attache 
at the United States
Embassy in Tokyo, and his assistant, Mr. Yoshio 
Nasaka,
served as interpreter on the tour.
This report presents a summary of different types 
of aqua-
culture in Japan along with personal 
observations about these
aquacultures. Also included 
is a summary for each of the
various stations, laboratories, and private 
farms visited. The
purpose was to assess the value of 
Japan's aquacultural
methods in terms of possible direct 
or indirect application in
other countries, and to evaluate 
the present and probable
future status of aquacultures in Japan.
SELECTED AQUACULTURES OF 
JAPAN
Detailed descriptions and discussions 
on cultures of eel,
ayu, yellowtail, oyster, and shrimp 
are presented in this sec-
tion. Information on each culture 
was obtained through
observations and interviews with 
research personnel or farm-
ers and from reading published 
and unpublished literature.
Japanese Eel
The Japanese eel (Anguilla 
japonica Temminck and
Schlegel) is one of the more 
important fishes being cultured
in Japan. As with most of the fishes 
cultured in that country,
those for stocking ponds must 
be taken from their natural
environment since the eel has 
not been artificially propagated.
1 Assistant Professor, Dept. of Fisheries 
and Allied Aquacultures;
serving as Chief of Party, AU-Government 
of Philippines Inland
Fisheries Project, Manila.
Little is known about the spawning habits of the Japanese
eel. It is definitely catadromous in habit. 
Probably its life
cycle is similar to that of the Atlantic eel. 
It is believed the
Japanese eel spawns somewhere south of 
Taiwan. The lep-
tocephalus larvae then drift and 
swim with the Kuroshio
Current to the shores of Japan and 
other countries where
they metamorphose into elvers and 
ascend the streams. This
occurs from January to April in 
Japan. During this period,
commercial fishermen collect the young 
elvers to sell to eel
farmers. Collecting is primarily 
at night during low tide
with the aid of nets. Elvers are 
collected from both the
streams and along the shores in and 
near the estuaries. The
elvers do not migrate into the streams 
until stream tempera-
tures are above 90 to 100 C.
Systems of culture vary. The 
most significant variations
in cultural practices are the amount 
of water flowing through
the culture area, stocking density, 
type of feed, frequency
of feeding, number of harvests, and 
whether cultured alone
or in combination with common carp.
Most farmers practice standing 
water culture, but some
flow water through the culture 
area. Stocking density is, of
course, influenced by which of 
the two systems is used.
Density increases with increased flow. 
Also, stocking density
is greater where the farmer periodically 
harvests the faster
growing fish or removes part of 
the population after rate of
growth declines and restocks them 
at lower density in other
ponds.
Eel culture is carried out in two separate 
operations. The
nursery operation consists of raising 
the elvers to suitable
size for stocking 
into production 
ponds where 
they are 
grown
to the desired marketable size.
The elvers, 50 to 70 millimeters long 
and up to 150 to
200 milligrams in weight, are stocked 
into nursery ponds at
the rate of approximately 300,000/hectare 
during January
to April. Generally, nursery ponds 
are about 150 square
meters and seldom range over 200 
square meters. Pond
depth is usually about 1 meter. 
Feeding begins in April
when water temperatures are about 
10' to 13' C. By Oc-
tober the young eels range from 
15 to 50 grams in weight.
They are then ready for stocking 
into the production ponds
for feeding out to market size.
Production ponds are stocked at varying 
rates of young eels
per hectare. Most production ponds 
are less than 2 hectares
in area with mean depth between 
1.0 and 1.5 meters. Re-
liable figures on rates of survival 
and yield were not ob-
tained, but maximum productions 
up to 2.5 kilograms/square
meter/year (25,000 kilograms/hectare) 
were quoted for
running water and up to 10,000 
kilograms/hectare/year for
standing water, with only occasional 
water exchange.
Feeds used by eel farmers were 
trash fish and artificial
feeds. These were fed in combination 
or independently.
When fish were the feed source, 
whole or ground fish were
to\ e\X iX , tlIii teefi ii j it it ( I ni l Ii i It Il t,, I i I I I I
holii.' bleatli the ft'edim i-it\ X. li\ idiX1(11l eels XXt ik t I eir
\oIX\ to and e\ (Xii iiitii the tit ,i ta
1
ke lutes of feed al.d \\ itii
'('toiids. \\ oi k thleir \\ iX v ack ijtil tihe mass' all I oiitiiiie>
bac
1
k finto ft(e iipeii pi 1)1(.
Miost faicisi feed ii l etsaX twXice cdii iit tis iXIs deteI
( iftolic temlper ature is fromn 20) to 2S At temopieraturies
hcon L0If C, tile fish ll e ]lot ted.
NA ot l4i jiifoiiitiiii \\,X iits biiiied oili i X ol> ili otliei
i')j)Ccts of eiiliiitii. The fi~iiXXill14 tt,ihic ,i4eX c' .t (iit id
1)1 II
FIG. I Eei, y,:- -00 . ho-o n p~n "It-1, ."d1 01) to
25,000 kg. ha. inloiong water.
used( defpclliiilg oil tie 1,iuic' pi cici diet. Trashl fishi XXcrc
f'oic 14(o- 1014iI. Wh oie fishi XX\\ elle l ,or liiX boiledt to malke tileIl
11111 I piliattilile to tihe cti>.
iThe lioiiedX \ilil(c fisih XXe strXiil14I toge(tlli- i11 i XX\ie'( liX
pitlX~iiii4 tihe XXiI-( thro11u14h tile iici of ear ii fIih. Tile sti ill114
fisii XXereI thir suspenided iii thie ipolnd totfi all the fii'ni
1
had1( heeii Xtr ippedl ,iXX ,\ aiir ciiinllVeri. (;olli fish XX\as
lole O itrI 1 it balIl tol pla~cedil ito It XXire -ilesI ti OX vXlis-
fpt'Ided illt the 1)111( XIII face. 'I'lie b)ottoim oif tile ti \itsX
iI1))l-i llilIti' 12 iilii I)CIOXX thet XX atei sIIIface. ht liiost
tiomii ffies fer1 toil \\icXXII holse illackc-l, i.llakerl
skippjer, ,ii audio> X . IThese triltiI fishi XX\iw plrcllase'r for
:t)0 \ell kfiloiiiam ($0t.014 pothil XX ]l biasedI ol tile exchltl 4'c
rate' of :361) X 8ci .0 .ft
Al tificiii feced> 0 vtid i :olipositioli, hilt wel ('cosisjt-
('IltX 1111411 ill fi,>hi 
10
t',illT'e foloiXXY 111 itre exampes of sm
Fis il 'i'll IgI'iiI
\% 
1
tcit o oaofol*(olhtSa
1 2
Pc't. Pct.
(10 65
,2t
:3t0
100t
Feed
Eels
fices (0.15 to 0.20)o
111111'' cvis f.. nto tIw5 00
f1 t) Ot
Th'il to( kIli- Ic I It ) ] l o ol p11 t llif> is pp (11 ) ill ILt) IX :')()
Pct. I/i
721
26)
10i 2
it00 t100) FIG. 2. Eels feeding on) ball of freshly ground tish
1 
and flout
submerged feedmng troy.
Sal >olly
fishli t (cilt) cos~t 7) k
0 
li St.0tlt)i.
XX itt'l tio fil Iladitll. Thie dough
4
1 XXit , oiXliIetd i11to t hil
('onis IXiii> of II tificfal feed,, XXcr I'i ,X iiXX asX 1.5 ( 1.5
kilogi ,i(I iif feed tti p ioi.'e 1.0) kfiogrin1 ei) . Oil tfii', ai
fish d itet, til IX ion fi Iai14r
1 
fi 111 6 to 12, XXhichlisI t'Xele
tidiXv , il Xc i >1(11ii o 2 tio 4 XX itli ('oiectfiolI fill iIisilf II
Thiiie lt, r e i] n oain l h od h
4~e il ttol\iss id d ho tc n po i \t rtcal
til l i s ,1 tlCe) \otiid' hugIll fl u' ii,I impot'etir, XXd (en'
thlere ,IIiX (' 1c, are) i aie lo.cpiec i( emml
loIt2' llcr ,t ite o t'lX ( ill111 tille~ 
11 Sh i X k i') ic XX \I\]1le(
i)th r 5 'ill >.0\ I 1,ii lilt X Il~in(Xts. ilI i 'X('X 11 a
frot Frini , 6 5o tolsX o i T'XX ti aiii i5P'~ii It tl tfom t ci, idl.
XX olll'ci t ettd fuivil lltillil \iXatt',I of IjIpail 11111111 tiii' hOT
FIG. 3. Sheltered feeding station in eel culture pond.
ss itile tite catchl ]itls itecit dicitslit( oS i tile 
iist Sc',o 5
Eisers iiie sippeditet Iit a fil as 
Eiurope ill plastic ias
ss licil coituiti about I kilmrti 
dil,f eivs ~5ait silitti illits
o itis ltt'e iic and \ x(4el. Ice is 
paicked .11 utitch titi ouitsie ttt
keep'
1 
tutir meltabiolic ri te itt
5 5
. P.,ipected illttutiits Iill
Eii utp is abouitt 101 pcer ceiit 
'tillket-size eils arci sipp ei
ssitht ci' culittire, somel f' ni siicit 
ari 'cCI ttiii tit ii, i pro
ittiii ici~ 'ut oil the futture of tilt 
ii iciisti S. Ill tihe tttoiitsit
p itgiplis stlitct of tue imiore 
iill)ti tit probiemls ri ilr is-
et1issici.
Elisci iiiel s are cieciiiiii (4 awiil tite 
ale ailreacIN iii shot
siippti . .\ppmiet~itio otttiit kittisss tue 
i easois tor thet tie
cliiiit. Ht'sticiueis at Sizuolika Prefcturei 
c statedi as potssiii
rei ts. Iolliotil i tite (i~s imd 
e iic stuariies is ditfiitt t'i
plti tlll lilt 1.tpaii ,tiic is il.picis iilciecasii(. 
ohs itnisis . pdl
Ilitilil cotiilc decrease tihe cis ti sitiiti 
. 1111 it is al51 iso hittts
thai ci,sPimps tlihe ts islls he 
t t11iteiecle 1 it i
ss iti kngi cl toeitleiits shore th' s tcti itiw 
d e tit i' toltil
iic',cst ul iicase rhaps it/othe r ii~ s a oti teiciic 
pi tiit \beitll-
1citit ttii s11es ofiisccisi '1 tht ,lvIs a ptiti 
(dus t'itilt'
of ii'ctittg c~ a ltile itricii('is it arestt 
o ei tcs stitts ose
stc tet spil it(il pTtiilils Fliii tuud ehetsiti 
caussi ,ctisitb
li'i ,u\ t tlii's lts lmit itid ptti hilpt trtue 'Illtris 
i iat
ces sts.hit' pill
1
ill ,i v s icii ttii i lliiice itcltcc o' \\ itets iitt
I esciits it sttisttitiain ,llitiit oif or1(,ini(' plilutionl as %%el ii s
quires(' i1 high ptci c('ltge ti, iisso~S ti
1  
05(Tell ill thei %\antir
Discitse itoi ptoor groth t areI( oftei tetets 
of redced~ti
ox-,,gel licstis. Kills (fie to low~ dissolvetd 
0x5 vgcit i t iot
cltiit' li fli .t( tib fio t hle oligeioiis o ftc '1 
fIlc' l )tolls I
(lulis ptitcltioi potentiatl, obsti icts fish bars vest. 
cretetis
poteiitii fish kills tihrttugih t)\\c (1cpIitliui, an1( 
d Caist's
(:titillhl cillP (0(tpriois carp/itt) is somtetimtes stotcked illI
111.1 iltt bte thei best species tor tis puirpose. A 
mixe'd (ill
tore oi sciial species of hislics, 5 it i cci b eintg tue pti 
tho
poltititii I tiro the teed couldi ibe gi c'.ti i educed. A 
ata
sotiitit;ii 55ul bettilt to teed thuS.11 tiil'tdi fedis 
iii iake tor
teed loss.
Elii laiti 5 itiist ciepeni til iiati 
to stiupis~ their stocek,
f01 the it'ihiis ilot b~eent spas itti artificdli ' i.Ther e illt st'S
eral i Cdstlts \\h i ardtifiiadi spamio of11( liss \tttiid inbe 
i adiill
tirettlis. Al-it l m'iS lentione~d id'- tilt irolemi'ts 
of clcciitltl(4
estuaies ss ich thiteni the eel sul. iHiteser 
ei istilig1(
1 epi ttclictitott. E(ltjiiii ii l-tilit 15 tile i iceci ifor geiletic 
iln-
p1 i-melil It otf ctis tiirouigh scctill . Thue tiliS w5ily 
thiat
fii ilu c a dill itt5 e tihetir eti stotck itti diisease resista,lt'
tastei ro titm , andit ottier diesiral ditit' d actei istics is 
tiii ttigi
(rest thie itptlliit heiidifficutelt t i ('lis.liiii is arificiltt 
l it'
Eitap ilhatt i iitifi mi tere ii(iiiii s e iiiiiem 
iik'is-
Ayu
The als i (PII t'ttg/sstis i/ t /ts (i tciiick atici SC hitt'
it iittt the igh4iest, malrket pr1ice of timat fishit ll japiti i 'l 
itc
jupiitese cioiistidei the fish i icitct idi serve it ilkedt
whoilte ss itli iheadi, skiill, mid s iscel ,i ii itict.
Th ii 11 is ail iioini tiittis fisih. T fi igeiri iigs speid 
the
ss ilutr ili thi' e s st Milei thley Iced prilill, otil I /ttlini kttti 
.
iilei. 'Iiuc schooltts migl ,ute inito tilt stii,in llieciss itei 5 i Itli
s iicii tiuc iitsc to ill -
t
ti(4ist ioi Septemberte to tilt hiss r
regiotns otf the sti eitinihere tite\ sptissii. Spais hg otccuri
fiilg('i hugTs, timis comrpletinlg the cs cii'
A iiioitlckt' ifi o cailedi ti,sii, iitliitiiilg Like' Bissi
cept tit ai liife sti4es reminiii il ireIisisstt'i
Vi'igeri hugs xx tic collected foi cuffin b\ h coilninei'itl 
fish
cieiie as thec fish dsceiitletl the stretins. Boithl the 
ii.r tilii4
istoallv raised separatexy C ollectors5 that 
sell to cultur e
farniers ilsuafix receiv ed 9 5 CO (80.02) 
pci finhiget hug. \leaii
size of fiolgeri hugs for- stoc -king wsas 0.2 
gu-am dodia 7 ctiti-
Ax u wer ciraisted iii poindts andc liuiaC popiia 
ill0 ciri i
ra Cless axs. Thle lol loss to is iiloi iiiatiouu ColleCCIi 
hug f11ailolsk
11iuiiiied dx 0 ciiltti hug lauiui aiid pi 
ocessluig facllits oecai
Iiauuiiuuatsii. Shuzi-oka Pu efeetiuu e.
TI e f acilhity con si sted of biotht piouds au ud 
piools xx itliflow-
log~ sx ateu. 1h lituitioiits of' priodiicfiii \\ as 
ill octagoli shaped
poiols w ith the 1dCo100lte staitdipip,, s 55 vs f orli liii55stc 
C eli(isal.
Titev wrcie con istruictfed of' ( ici cetC adl 
c 'mit aiiid 18(0 cuic
meter s of ss atel . A cootitoos suappix of wate ,ei tterijig 
otil
ooite sideis ofi each pooil cr1eat ed 
a \e ei N oii oui ls eon eli
estimtedC~ to beC ab out 10 cenItimeterls 
sCCtci ill tite eli tev.
The b ottomi lif the pool xx as slop id tiissard 
the cclift I . Sol id
w5 istes diviSeii li gras its ail i ii ilei if 
were ri CIOSed sx itli
the xatrox erfloss through the staoi dpipe. Eachi 
pool wsas
eqf uippedi wxith aerationi.
Thle fair had S sluch piools, all xxithiui a single 
bildinig
eclosed wxithi coriii ga tet fibe)Crgl ass. T he biidi hg ali 
iixxatel-
lteatiiig eiiipineut peirmittedtl empelalie ciiiitol 
aiid, thiere-
fore. lilailitail ied war('dl' lilid gri 055ilig coiiditioiis ill sxMili 
fioli
clrops xx cie pr odueed aiiiiahlxv The total 
insvestmen t \5 .s 10)
milioui ynl (856.00(1) xxhieh iincliided tlie hiuilhiig rae-
xx as Mid equiipineiit.
4
FIG, 4, Octaona no!.ncrete raceways for ayu culture 
within fiberglass
building. Note waler inlets on sides and automatic feeder 
in center.
Stoekitig tdeinsity pt'i racewsay xxas fromli 12, 5M( 
to 15,000)
fin gel iigs. A cilet'tx PCccl xxe \as fed bY hl l tsx let',
dlails or moire fi ciuelitl its aill aioniiuafie feederi. 
Fe 'ditg
Irate xsas not ohtaiiicd. F'eeid ('lli5Clsioii ill 
gi osinig the fisli
from (0.2 to l1t) gri -isi/c asen crgd abtout 2.0. 
1Thte ax i is a
vel active fih aiid pioiiall is hut aii efficient 
tsci etel oit
feed. liiiss er c th. le folimilatioii 
of dlit' f cc \\xas iiot knasx i,
so tlthe xxa .i io xx ax to deteimilie xx lieil 
the 1 Cjjitix clv pooi
coeta Clsiii ireffected lows de cii cx o1 pool i feed qpi al itfx
The cuilturle petritod sxas aippr oximaltely 901 dax 
5. Il that
periodl, the fish gress from (1.2 to bcsteen fit 
iid 10 (Yragiats
xxith abouit 91) peI ceInt suil . Ciiltiiie 
tempel ttirexxa
miainitain ed at appi oxanatelxy 18 C. Y ields 
pei piood i iiged
from I to I1.5 til s crop, xxith fonr 
crotps pei c val.
Tb e owneir proces sed lis pnrd lt io ii 1 i s 
ilp itoixtillo Iiog l
it.illi gxxfolt' fish. Thle icedl fish xxci eici itippl h\x ( iaii,
to miiiikets iii .ikai auth tiks -o. 'I'lli ,5 ('1e sftted thiat hit
alss ax 's r ecetiv ed ai preiumiii pje itt' l hs fishi xx 
hiicli .it tliit[
timie 55as :3,0001( %eni kilogl tim (84.01(1h)). 
Thibs xxas .i high
p1rice, but pr odtfiii andd miiketii ig cists xxe-( 
c vtcxei high
ailsio.
Yellowtail
het' s eliosstail 5S tiot( t/iiio/iii sadiata I ei'iiii' 
mid
St'llcgel )) is its fal the mtost iltptit 
spiecies iof iiiai lii,
fish bciiig ciiltiiiet ii japauit. Tlhe pi 
iiictioii ofi liinli I .ise'(
itint fishes iii Japain iii 1967 ,amouiiited 
to 27,101:3 tonls
gioss sseiglt xxorthi 8.7 billioli xci(824.1 
iililiclii) . Thel( pro-i
tloctini i coiisistted of 98.6 pci cent ( 2(6712 
toll s) Y elhlowtaiil
(0.2.5 pt' c'cif (.53 tons) pilicir J'ig u 
i ppts i opt /it n.s
.utld 1.2 peci .'it (:3:3S toils ) of otliel miij 
e fishes ii uclidiu i
dlii) C jack ( Scritla piiipuii . c its stripe 
jih ack ( Litwhiit-
tri ll i/ i(iatiiish ) , I ccl sea blviii (Poaius 
mniol ) I~ipai
li'lieil i titfish IOp/ic gtfilx ptioti at li-SI. 
auid itheis. Thle
Yellowstail pioidilcedi ll 1967 xxix s aduied at 82:3.5 iiillioii.
Although cutiurei of x clltiss t uil dates back to 
att leist 192~8
oit Sliikoko tsLtiid slgitific-lit giriiwthI 
of flit iiidtisfi s dates
biack tit abotut 1960. Il 19.58 iis :300( tils 
werce pi oduiced
iiatiiuifi ini 1962 fltde ie er 1521 toiis, andic 
iii 1968' ov er
:31)00(( toils. The hulk itt pliiuioi)ii apjii 
ixiiiiiex' 7.5 pel
t'tiif of (lie totail, is iii tlit Seto Iilaitt Sei 
i tgiuii of' soiiuthi
Japain aiid aloiig (lie soiuthwsest coast.
Muho l ciedit fo [ii lit' r apid gi i\%t( of 
x tll1 isstail ciultotre
canl it' attibuited lto t e siucce'ss fu tieseli pm t'it 
iof thte cage'
clture sx stemo begiliiiig ill 19.54. T1his meftiod 
.ict'iiiits hftr
(lie ho ge'r part of 1 the fish pretseiitx fieiiig c'ultuiiedh. 
'(hle ie-
miuiiiccr ar1e pi odiiccc iii pit ils.
'Le x eflIsstail is ai ilglatm x fish that 
Iilix ts iia ithfll
()kNax ~'c M* i Ill o achlid uc it r (Ix ito i Kyuishu 
lsfiiih
tpii ill Apriiil ori calls Nit.i Spa\Niiihug 
itoccturs iflshorl
istiif lix eail- lx\has
lRes-ch tiei's hase t'eceifixl- dev eloped fecliiiihtics 
fiol tnti-
14iallx~ spaixx Iilig birood ' vcllitti taike'i fin liiattil 
wia.tt'rs.
Tcel iil es fiii liatciu auich ri iisu ft'e pi lgeis 
hase t'isot
It 't i dcx cloped . lii ~ r is x11 1 tesie method 
ms at f 1)1 i 'xi .ri
utpht ciifo %e ci Ituicill 'l tN i oi xci \e imitedi bais. 
Ilii' htilik
(. the fix is takeii fromli lititl ifxx.icis. 
Thle fix N7iae iii'ttt'
hi ii t'e sea xx li .ippi'oxiluatchs 2.5 millimters 
miid 0.3
xxweeds. Fry are iiett'cd lix inns ii iit-li 
ficsed c'olltctiors.
Catch pert' lietoi is i egihated to e'lsi I' aiist itscifishiiii
(lie iitili stock. Iii 1967 total catch xxas 
liitedl to I
fllittli fix.
Frx c'oll'c'torls seli tit farmiit' Mit giauie 
ft'e fi'y ilitit
I ll ~sits t'ages aipproixiimately 2 x I N I 
uietc'r. fT'e cages arei
c'iiclosecl xxitli flult' mesh niet. (Gradinig 
iiitii irelaitivet sizes oh
p'i-ici iif 4 to 6 xx ecks is r equired to 
iraist' thlf\ tit finigtri
sligs ol'.apoiaev8t 0ce~ieesad2 
o5
All cultures tile ill cage's siuspc'udc'c 
iii bas xx v is chr stililit\
is 16 ppt. or higheri. Thit fit'i hugs toe 
restoctki'd iiitii ii,,
ciiclosed tcaigcs osiiailx .uhoWu 6 x. 6 x~ 6 
unctc'us. Stockitnig
densities lalige firim 4(1 to 7(1 fiuigtrliiigs 
per cuiiic tittt'
Glio\t55 raItt is I tipich dlld fiugt'i iiigs stittckiet 
iii Iliith lout
r ange(t fiimn 2011 to 7(00 gralins ixv Auguusf' 
(6(1( toit W) 1.((gultis
byx Octobeiri anti 70( to 2,000~t grants 
lby tlie endi it! Iecein-
litr. Harve tst btegiins iii Sepfftee iii 
Octitbetrx lhiu a stiffi-
t'jii'it oitilili oii fish is~ r' iclc'it' hefu 
inaiu Ixtiilt' size' of
ove ('I11) tlit(, 1wit 41 oxxiil 
4 xtiii . Tlii it s tim(id( 
piwti('
it) 'rolithl all~ \\ iev 
st'irsoti art' ltoligext. At 
tixe el of
tli t( iito l caer tite fihi 
cn milal ketedi at 4 ti 5 kiloniaixi
each.
Pi tt cli i of \elllti\\ tail 
il cages ill opii xx atei bax 
x c
i 4cd ahtiiit 40) kilmiiainx cuic~i 
iiteri I aligixs toiml it to 5(1
attiitd( xxitli ('lliliel catfishl 
ti cit 4c iii cliosed p )ilix ill tii
lBaftsx geiei allk consxtrucItedi 
ofi blinloo id attachled tii
totr tite ffitatimy 4iet eagex. 
'I'lie irafts Iaxlitb dixided 
iliii
secitionis. 'I'lie, cages are 
lisilitllX c itpoxeti iof a siingle 
lax el
of inexil, lii a xciiid lax 
ei is xomiet flex ilicled 
to elli lie
agaioxst fih lioxx fro ( l 
it tiiie. ITle italtx tixiallx 
float,
l)iit till, ie! eil 4ex. if p~ i
1
)perx cox ci td. cali Ilie tx lo ered 
to
(lecpi tei ]etc clx~ it' desiired. 
Sitl-i te ileixa oif illiidilill
('l 4t.' \ il X fi i 4 ttt 400f siquire 
meer iic i.'i filtie\ i huge ili
idepth firom 2 to 1~5 meteisx A clilmmii xi
meittersx
FIG. 5 Bambo -frmdrf o uptm e
FIG. 5 amotrinilCled i!rSoi 
tragi alt
cuture. Prstdudionaveragede40akgpmroitcage.
diltsiot hi 4tx jurcisditio 
eU'o t xp(ilict
11111itllx ix ('fiat t', ecetpt 
xx ieu tlic a
tio proteiitt fixsh ctilturit a iti x 
ixc tit',
fli tac is ttllig4itt'(l to, pt fihxreln 
licx
the ilil it xto deciiliiied.
ii xAx txli ot fiex lt/I'l tittl'xcin
itigl x\iii xixs orl i ftledi-hx lediogs 
ci o
xx i' ii'ittcoi lmxlfact cotn tirilxi.iittheiftx(
ceiit mii tlitx oiccturred ill 2 to :3 
xxeekx.
xwith fiih liii ig xx Lit(' flexsihu 
11otalhx x
ix ('i lowxx ti x it cl'Oxsta(t'llix. 
Alxo iiitt'it'
1
)ititix 1 t' fittricl bcehix liil. 
This plai
tixill tic li/ ii oil lig iiplolihl to itis 
loxL
FIG. 6, fa nrooo frroned 'oaft with net 
cage
Z'e usxed ixs4 (6 x (4 xx 6 i to'ei'(fijec 
gitiiiii iiiid thl xiex ('( to rllimx 
the
shiells. Th le tesultinig shlimp 
flo couild lie stored iiilefiiltelx-
et~iial imiiiiit oif xx atei 
to tiiit asate xxic 11(1 xixs 
x
1
)it oil
grLaxx oi p~lates axs otIlt' xxoil 
s1 pireadl buttii l ii eii. 
TI i
glitxx x\ itl I tle attalied 
xl i l lii) pilxte t s lx tu 
u x p~ei It'l illI
tihe (( 41.
Fi ii git oo l iii ttiid lalrye ge l 
i xx ('ie fed xx\)to](, or xlied, 
r ilt
ili it iffh ilp\iiiiite'l 
.5 to 80) per' (,('lit xatictx, 
or Ioiighl
itt per (('Iit bod\ xx eight 
I alpproiatekil 2.5 p)ci, ('('lit 
(In
xx p'il d1tixv ) rextiltedlii 
tiniot th not(,f(,(tt gioxx tli. 
\\ hl
thisx is dix\ idlcd initii 2 lids~ 
pei' dix, ftii ]iii gel- fixli aill 
:
Mto -1 loii fi1 
(lxx tl lt' xxk \\ix sitsli('tiii x\xxtell 
fed ait 51
per xt'ii (if liodlx xxeight 
iii less. XX lii xxater tecit)'i 
lililcx
xx-( ci to\\lix 14 CI(' flis 
\%xii xxe d Ac i t 101 pe 
lt iii'm lim'
~ '(fIn loii fixli 
upl tto 1.5 kilogi is alot 
10 It 3.tt (ix- li- fixsi
farmerot' iittit :3!0 xcii kiltri 
ami (f0.t04 hpttiil) xx it it 
aw',i
cages used in yellovitail of 2.5 tto 
60t x it kilogirai dcetiidiig tIl xlipplx 
FlTius, toittl
feed cosltx xx cue i71oiid 21 
Itxeii kiltigrami (8f)02S pounid)~
ilits' ill the blx . for fih i produed t 
it cii',tt
1 
t puxii of titii I 'xaiehe
I fxliiir I ~it. '~ x cieArt'iiia 
it il( t ise lop ',ic l t ttil 
th lipti't reiearcher
dtuil Icc ri tlit'
iiig ~ ~ ~ ~ \\l filii ilt, pt ttii lilltili 
to ftc~co xe li Axo es.i it Itx 
fppare frogm
i'ltx thii tit 
i'cp plett Ie hi elit ltcl 
tl''txfll
tltt lc~l ti xcllox ~ tiii 
xr athi tt'ioat'ifiil dct tot x fit\ 
tal emrixxtltIill at
iel (i ttlt oil the ari 
leas T i 2er 
c '. mca mad 1 ttxish 
a it ttip i tit f'lesh.
'1) ',nleit ccl lii- 
Whft24 to 29 C 
xxoei h zit le fixbsgi 
itxx ttci part by xlilitx
clitill ~ ~ ~ ~ 
ox fei Alo i( r iii rit' ii etohal 
tt'iitl Aiilscx liilt' 
t .i! S li
1  
:31l- to gt
hug t
1 
lix x ax t~it ill the lotxl 
to1( higep pltcd', fee xlrecix 
cl. ciiig uccessfl."li
tiligix tlit firiici ' l'illicltiotl 
tliictclipeitisi'r dixll an ':31C 
fi-
the o\\ itid Il~di lim ts, esp ctielv. Vce ill cea,, i7
Both of these species attain an adult size of 1 centimeter or
larger. The recommended treatment for both was a fresh-
water dip for 5 to 10 minutes, the duration depending on
water temperature.
Few reliable figures on production economics were avail-
able. Market prices obtained by the farmers were generally
from 400 to 450 yen/kilogram ($0.50 to 0.56/pound), but
ranged from 330 to 520 yen/kilogram ($0.42 to 0.68/pound).
Cost of production ranged from 270 to 350 yen/kilogram
($0,.35 to 0.45/pound). The margin of profit, therefore,
fluctuated greatly. Farming operations were usually by
family units. A family-size operation may produce in one
season about 10 tons of yellowtail. At a market price of
425 yen/kilogram ($0.54/pound) and production cost of
300 yen/kilogram ($0.38/pound), the family would realize
profits of 125 yen/kilogram or 1.25 million yen ($3,472)
for the total 10-ton production.
The following is an example of one farmer's breakdown
of relative production expenses:
Item
Feed
Labor
Fingerlings
Management
Facility
Maintenance------
Miscellaneous
Relative per cent
49.4
11.2
10.1
10.0
8.8
5.1
5.4
A large number of problems threaten the yellowtail in-
dustry in Japan. These problems, individually or collectively,
are certain to limit future growth of the industry and could
result in decreased production.
Degradation of water quality from the various pollutant
sources is progressively becoming more serious to yellowtail
culture in Japan. At present, the farmers are able to culture
in areas where pollution from external sources is not a major
problem; however, such areas are becoming more scarce
while the demand for suitable areas is increasing.
The feeds used in yellowtail culture are trash fishes har-
vested especially for feeding cultured fishes. Other cultures
besides that of yellowtail also utilize trash fishes. These
cultures are also increasing in magnitude and, therefore, the
demand for feed fish is increasing proportionately. Hence,
it can be expected that there will be an insufficient supply
of trash fishes to meet future aquacultural demands in Japan.
To overcome this problem, artificial feeds must be de-
veloped. However, present indications are that yellowtail
may require a feed containing approximately 70 per cent
white-colored fish meal. Costs must be considered and at
present such fish meal sells for 70 yen/kilogram ($0.09/
pound).
A problem with disease, perhaps unnecessary, is that of
disease-contaminated feed. The practice of feeding raw fish
has contributed greatly to the disease incidence in cultured
yellowtail. The fungus, Ichthyosporidium, is definitely a
disease transmitted to yellowtail through infected fish used
as feed. Vibrio, a serious bacterial disease, is probably also
transmitted in this manner. Both of these diseases effect
significant losses on the yellowtail industry each year. The
practice of feeding untreated raw fish put many trout farmers
out of business in Europe and in the United States before it
was stopped.
The present practice of depending on the natural produc-
tion of yellowtail for fry for stocking purposes has a number
of disadvantages. However, fry can now be produced arti-
ficially from adults taken from natural waters. This is a posi-
tive accomplishment, although not a completely satisfactory
development since parental stock have to be obtained 
from
natural populations.
Japanese Oyster
Japan is the world's leading oyster producing country.
Their total production in 1970 was 45,000 tons of shucked
meat. The area around Hiroshima in the Seto Inland 
Sea
produced almost 70 per cent of that total and should be
classified as the oyster producing center of the world. Oyster
culture originated here in the 17th century when fishermen
began setting rocks and bamboo in shallow water for oyster
attachment. Japan is not alone in the oyster farming industry,
for culturists in many other countries are culturing oysters.
Over the world there are many species of oysters being 
cul-
tured with a variety of techniques or systems. Almost all
oysters of commercial importance belong to two artificial
groups: the flat oysters, represented by two species of the
genus Ostrea; and the cup-shaped oysters, represented 
by
four species belonging to the genus Crassostrea. The Ostrea
possess two flat shells while Crassostrea possess a dorsal flat
shell and a ventral (attaching) cupped shell.
All the oysters cultured in Japan for food are the Japanese
or Pacific oyster (Crassostrea gigas). About 1 billion seed
oysters of C. gigas are exported to the United States each
year. This, plus the production of seed oysters for domestic
use and almost 50,000 tons of food oysters per year, places
the culture of C. gigas at the top in world importance.
The spawning for C. gigas is from May to August with
definite peak spawns occurring during the period. Spawning
normally begins in May when water temperatures have
warmed to about 201 C. Optimum temperature for spawn-
ing and young development is between 23' and 28' C,
while minimumand maximum limits for larval development
are 15" and 300 C, respectively. Optimum salinity for oyster
production is between 23 and 28 p.p.t. Highest setting of
spat larvae is usually in water of about 15 to 18 p.p.t. salinity.
In spawning, the eggs (1/2 to 1 million per oyster) and
spermatozoa are released directly into the water, where ferti-
lization occurs. The zygotes develop into swimming plank-
tonic larvae in about 20 hours. The larvae feed on small
plankton and suspended organic matter. After 10 to 14 days
in the swimming stage, the larvae settle and subsequently
attach on a clean, hard substrate which is usually shells or
rocks. After attachment, the young oysters develop new
shells and take on the characteristics of adult oysters.
The attached larval oysters, called spat, are the stage
obtained for culture to food size by oyster farmers. "Collec-
tors" of various hard materials are placed in the sea to col-
lect the setting spat for commercial culture. Collecting ma-
terials used almost exclusively in Japan were scallop (pecten)
shells and plastic plates. The shells or plates (collectors),
10 to 15 centimeters in diameter, were pierced in the center
for stringing on a galvanized wire (No. 16 gauge). The
wire was usually 2 meters in length and contained about
100 collectors separated by 2-centimeter spacers. The wire
with collectors, called a "ren," is draped across a horizontal
bamboo frame which is attached to vertical bamboo posts
that anchor the frame to the bottom. The ren is suspended
with the center across the frame while both free ends drape
vertically. For spat collecting, the rens were usually placed
below low water level so they would not be exposed to the
air.
The time and location for placing the collectors is im-
portant. Placing them too soon will result in attachment of
Sttte, oi tilex \oil](] ht ut iix e%( tihe trip. Tieltiiar-deiim
periodutil llii lasts hoin Septembter liltil limcle \\]itell the
foi exportilig. \litit dl' uring tihe periodl froml spat fto seed
timue of settingu liiitil lIXcr 'ti are .ilout 1.5 illinmeters it)
'% size) wxjihout the flattlelflliiy proessx a', i ltes aliit S-,)pe
lx xtis x Ire aboult 10) Iilllitetet x, xtiitetjiieit lont-tall)', is tle-
-s.~~~~~~~it 
te 
a -t i t till 1)I.ct 
o ul u e
xxollictor tiit' iii','t'' i seexd)i'li'ie i nii ri' s ttil1(1 olx \%l'' ofil
L'
7
.ei -uirtm inkda coth',is Ti see ie i lgx
07 ~ ~ ~ ~ ~ ~ ~ ~~~~i STns c~<oepoicini 
9  
e on sin g of 5 t o ii5' Ileti i lmt iii Io ixito-l
metere oflir illr withl shells orv 0.4een prooduhuctdiostrs
1"011 ift'ti olr-ilii. ani rackf~i Ix t' i , 1 Al is 'thee ite itti ,ito'
.0, k' iil[i'ttltI~ l'ttxtttg 11tl it xi x cetit S x ilu lt is susie ndx ed ire l th ' iititx atl s tIe iiitt'
* _~'f~ ~s~-- ~-~
FIG. 9. Oyster rocks exposed at low tide, ide fluctuation facilitates slack-
ing and harvest operations and allows use o) the iniericdal zone tor
culture.
(ii llt tioleti ci letoil th eiil pls hl Ioioia
po le Iatilt'tileli 1 i'lii ll Ill 
1
) ilt r i x ill)(ls til e'll li t'
polsx t'italhi lens stte tiset' d frontli tx tx on stto.i 
iil
liii ci 12111) ililtt'tjlldllo roes
10 retll scsaepoucdb w \S(Ii:I-el
IG z C :, , , Ik
-\e erage protitioin pet 10 meter wlit 1s aiboult 4 kilo~tililis
lii shucitked (i at or 45 Kilogi atos total xx (ioilt of oxstel 
5.
Riiiigc of 
1
)rodlcietoli is hii 11 2.5 to 10 kilogr ams iot- shlicked
mieat lull (3)) to 1 10 kilogiramls total xxeiglit r'ii). A raft 
of
S5t) 1111, \\ill hax prVoducittionis of shued~t mieats 
aic rilloT
aikoit :. I tlons inid( 1 aimlim4 I 11) 2.5 to 5 toins. Ahoiit W( 
pei
ceIit ofi J apiix ox ster pl odlittiot i is for Iliiii e tollsoo 1
1
)t iol .
Most of fte ieiiiiiiilt is ixtnliedi ibefore exporltinlg. 
All sizes
of ox stels itre iliiti. 'Tie ,illet ie slmoked( beioic caiol
Faiieis call exp~ect to sell thetr ox -stei s loi- 
abooit W5)
\(11 kilmiiii m8 0t.70 pll) sliiiki'il 55 dr t. 
This is iliot
1.9 mhillionl s\ell raft S$5,27,T). Costs ot priallitioll 
itiI I elat
tkex ('ixiiitl. A (1 hog' illtllilt of iaiiii is lletessdl'x ill thle 
ciii
Elivks alilieaits aie lditells apkl-slit a iectile~ mIilstils 
iii1
tur iesilx e11xtees xx ipeiteii siiilted iio1t, ipi 
ie iiiijeti
Pli sitex (111( eiseaseniiis :11e ip~ ltixseioi) raftsiortiel I'll s
bells~ the racksol lixte li ti lill eml oxex irll axites\ 
iid
IRsass i li afsil elflt ll 1)' 111 ifatix lll tile 
iiigil 0101'
t ax c ofiti (I \ li (11itiit's and adi tsilt.lCtl W11141 ind does~l(1 a l
d(11i Ii tx Ii 111:1(111 li andits effaltstaf. i T 11 11ste 
rillcas.
aiti1ve1 t lleilolltillei~ta11 cldtiix121 . l T empiatii 
t nfiioxsel5.
I lixx x (itd lix sl5ilditill bettl 1111 \ l~s~l rat 10111 
stlteille ill
te Ill aiiil xx iltil atl tiltlilt' jilplsai xse.5.il 
hl
Japste tlddsaes olr Kuruma~~ Shrimp idre Sri
SHI iob1 lt 1)1' i ill o i er aii' s i oe~r itparlas 1111 
ltite a11 Itd
R) 'ed i tidesl cIiitiiei'b (,iill ii ' ill tixx ,1iti.s 
\ileiclii
Japan with the Kuruma shrimp (Penaeus japonicus Bate).
Those successes, in turn, can be attributed to Dr. Motosaku
Fujinaga more than any other single individual. Fujinaga is
credited with culturing the first penaeid shrimp from egg
to adult in an artificial environment. He is credited with the
development of the system now often termed the "Fujinaga
System," for raising post-larval shrimp from the egg on a
commercial basis.
Production of Post-Larval Shrimp. Fujinaga succeeded in
1933 in artificially spawning and hatching a penaeid shrimp
for the first time. Few of these shrimp survived through the
zoeal stage because of lack of suitable food. In 1941, Fujinaga
began feeding the diatom (Skeletonema costatum) and found
it to be a suitable food for zoeal shrimp
s
. In 1956 he began
using nauplii of brine shrimp (Artemia) to feed mysis larvae.
In 1958 he produced food-size shrimp from artificially
spawned eggs. No one had ever accomplished this previously.
This accomplishment set the stage for commercial culture.
The limitations on shrimp culture at the commercial level
include low yields per area, poor feed conversion, high cost
of feeds, lack of success in the developing of acceptable arti-
ficial feeds, low survival rate, and high cost of labor.
Researchers in Japan and other areas of the world are
actively trying to make shrimp culture feasible on a com-
mercial scale. Japan is one of the few countries of the world
where commercial shrimp culture is feasible at present. It
is possible there only because of the high market price the
product commands. The farmer can get as high as 2,500 to
11,000 yen/kilogram ($3.16 to $14.00/pound) for live,
cultured, food-size Kuruma shrimp. Even at these selling
prices, there are not many farmers getting into the business.
In 1969, there were only 14 shrimp farms in Japan collec-
tively totaling about 100 hectares. Harvest from these farms
totaled an estimated 200 tons.
In its natural environment, the Kuruma shrimp spawns
from mid-May to late September. Copulation takes place in
the open sea. Sperm are encapsulated in spermatophores
and are inserted by the male into a special seminal receptacle
of the female. When spawning occurs, which may be many
days after mating, the viable sperm in the seminal receptacles
are released simultaneously with the eggs and fertilization
occurs. The eggs are shed loose into the water and both
eggs and larvae of all stages are planktonic. The eggs hatch
into nauplii larvae, and through successive molts, the nauplii
develop into zoea and then to mysis larvae. The mysis larvae
develop into post larvae, which relinquish the planktonic
habitat for a benthic one. The post larvae develop through
a series of molts into juvenile shrimp having adult character-
istics.
Farmers that artificially spawn Kuruma shrimp obtain their
brooders from commercial shrimpers. Since the gravid fe-
male is capable of fertilizing the eggs as she releases them,
there is no need for collecting male shrimp for spawning
purposes. Brooder shrimp are collected by commercial
shrimpers in the open coastal waters from late March through
October. The shrimpers, trawling at night, separate out the
gravid females and hold them in specifically constructed
live wells beneath the boat deck. Upon arrival at port in
early morning, the females are transferred to hauling facili-
ties for transport to the nursery. Transport may be either
in a tank of aerated sea water, in a plastic bag filled with
* M. Johnson and J. R. Fielding (Tulane Stud. Zool. 4(6):175-
190; 1956) succeeded in the United States in 1955 and 1956 in
spawning the white shrimp (Penaeus setiferus) and rearing them
to harvestable size with net production of 806.7 kg./ha.
20 per cent sea water and 80 per cent pure oxygen, or in a
container in cool, dry, coarse sawdust. The plastic bag
method is the best method of the three and the sawdust
method is the poorest.
Fujinaga was using the sawdust method. The containers
used were corrugated cardboard boxes with 31 x 27 x 15-
centimeter dimensions. About 30 shrimp were contained in
each box. Plastic bags containing ice were packed on top
of the sawdust before sealing and shipping. The adult shrimp
to be shipped to Fujinaga's farm were packed and shipped
from Nagoya in the early morning; they arrived at the farm
by mid-afternoon.
Gravid females were readily detected by the gray-green
ovaries showing in the dorsal portion of the body; especially,
at the hinge between carapace and abdomen. The thicker,
more defined the ovaries, the more likely the female was to
spawn readily.
Prior to receiving gravid females, the spawning nursery
tanks were partially filled with sea water filtered through
cloth of approximately 96 x 76 threads/inch. Gravid shrimp
were stocked during the daylight period at varying densities
ranging from 0.5 to 1.5 shrimp per cubic meter depending
on such factors as type and size of tanks, temperature, con-
dition of the shrimp, and others. Fujinaga stocked up to 100
females per tank (10 x 10 meters) in sea water to a depth
of 0.7 meter (70 cubic meters). Facilities for spawning and
raising larval shrimp have varied in shape, size, and material.
In the past, structures for spawning and rearing were sep-
arate. However, facilities have beccme more 
standardized,
with the same facility serving both spawning and nursery
functions.
The standard nursery facility was a square concrete tank
5 x 5 x 2 meters or 10 x 10 x 2 meters, with water capacity
of 50 to 200 cubic meters. The tank floor was sloped to one
corner at a rate of 3:100 to permit total draining of water. A
plastic drain pipe, equipped with control valve, led from
the tank into a chamber in the drainage canal whose floor
was approximately 0.5 meter below the outside end of the
drain. Water depth in the chamber could be maintained at
approximately 0.4 meter. The function of the chamber
was to facilitate harvest from the tank.
Water in the spawning-nursery tanks normally ranged
from 21 to 23 p.p.t. salinity. Optimum water temperature
for spawning was 280 C. Fujinaga stocked brooder shrimp
in controlled temperature of 23' C and began increasing the
temperature to 280 C immediately following stocking. Tem-
perature of the natural waters in April 
is about 150 C but
the shrimp can be acclimated rapidly to 281 C. Tempera-
ture control was managed by a combination of methods:
heating water; constructing the culture tanks below ground
level to conserve heat and prevent rapid fluctuations of
temperature; and enclosing the tank area with a translucent,
corrugated fiberglass, greenhouse-type structure. Heating
the water was not necessary from July to October.
Spawning nursery-tanks were aerated vigorously through
airstones positioned about 10 centimeters from the tank floor.
Each airstone was connected by a plastic or rubber hose
which led to pipes from a compressor or blower. One air-
stone for each 3 square meters of tank floor was considered
adequate and an even greater area was covered by one stone
if air pressure was great enough to furnish a high volume
flow. The effect desired was to have water moving in all
areas of the tanks, with the surface giving the appearance
of boiling water.
The average body weight of gravid females was approxi-
11
mately 100 grams and ranged from about 65 to 140 grams.
Size of collected females decreased as the season progressed;
in April average size may have been 120 grams, but by
September average may have decreased to only 80 grams.
Approximately 50 per cent of females placed in tanks
actually spawned. Spawning was influenced by a number
of factors including physical condition of females, state of
egg development, and others. Spawning occurred at night,
which was one reason the culturists wished to stock females
during the daylight hours. The spawning act generally be-
comes later at night as the season progresses. In May the
spawning peak occurred between 8 and 10 p.m.; in July
between midnight and 2 a.m.; and in September between 2
and 4 a.m. Spawning was readily evidenced by foam ap-
pearing on the water surface and the water becoming pink-
ish in color. The eggs were released directly into the water.
The number of eggs discharged per female averaged about
300,000 and ranged to over 1 million per female depending
on body size. Egg number increased with body size. Hatch-
ing occurred 14 hours after spawning in water temperature
of 280 C. (First cleavage occurs 15 minutes after spawning;
eye formation develops in 11 hours.) Approximately 50 per
cent of spawned eggs actually hatched. Fujinaga expected
hatchability to be only 5 per cent in April and May; 10 to
20 per cent in June; and 80 per cent from July through
September or until the end of the season. Adult shrimp
were removed from the tank with scoop nets after 2 days
or after the first nauplii have been observed. Dead shrimp
were removed when they were detected.
Hatching into the first larval stage (the nauplius) occurred
14 to 16 hours after spawning. The nauplius was about 0.3
millimeter in length and was planktonic in habit. Nutrition
was furnished by self-contained yolk; larvae in this stage do
not take food. The larvae remained in nauplius stage through
5 molts, which required about 35 to 36 hours at 280 C. Sur-
vival was usually 95 per cent during this stage provided
water quality was high. Estimating numbers of nauplii and
other larvae was easily accomplished by taking 1-liter sam-
ples of water at random, combining the samples, counting
the larvae, and expanding the consolidated number of larvae
on the basis of total water volume. The nauplii metamor-
phosed into zoea on the 6th molt as a nauplis. This occurred
about the 86th hour of the nauplius stage, or on the 4th day
after stocking the gravid females. The larvae were about
0.9 millimeter total length at this stage. In the first stage
as a zoea, the remaining yolk was totally absorbed and the
larvae began taking diatoms as food. The zoea, still plank-
tonic in habit, were unable to actively seek food, so diatom
density must be great enough that the larvae come into
contact with diatom cells at sufficient intervals. A fertiliza-
tion program was begun while the larvae were in the
nauplius stage. Usually it was initiated on the morning
following hatch of the first nauplii. Chemical fertilizers were
used. The object of fertilization was to induce mixed diatom
growth to provide food for larvae in the zoeal stage. Pure
cultures of Skeletonema costatum are no longer necessary
as in earlier methods of culture. Chemicals and concentra-
tions commonly used per 70 cubic meters of water per day
were: potassium nitrate (KNO
3
) at 100 grams; sodium phos-
phate (Na
2
HPO
4
) at 100 grams; potassium silicate solution
4
(K
2
Si
2
0
5
) at 5 cubic centimeters. Application of the chemi-
cals was practiced daily for about 10 days. After a few days,
Commercially known also as "water glass" containing about 25
per cent potassium silicate.
the amount of chemical used was adjusted downward, when
and how much depending on the density of diatom growth.
Diatom density was indicated by depth visibility and the
brownish color of the water. When for some reason diatom
density was not sufficient, finely ground soybean meal was
added as a supplementary feed for the larvae. As a standard
practice, Fujinaga introduced Artemia to the culture tank
at a rate of 500 grams Artemia eggs per day per million
larvae. At 28 0C Artemia eggs hatch in about 24 hours.
Hatchability was usually between 40 and 50 per cent.
The zoeal stage in larval development is probably the
most critical and it is influenced by water quality and food
availability. Fujinaga expected to get about 80 per cent
survival in the zoeal stage. This stage is characterized by 3
molts requiring 4 days (8 days since stocking brooders) at
280 C to complete. In the third molt, the zoea metamor-
phose into mysis larvae.
The mysis larvae appear as minute adult shrimp, but are
planktonic and swim backward, anterior end down, in a verti-
cal position. Peripods function as appendages for swimming.
These larvae are omnivourous and actively feed on the small
Artemia nauplii introduced as eggs in preceding days. Sur-
vival in this stage was about 95 per cent. The mysis larvae
go through two growth molts before a third metamorphosing
molt that occurs after 4 days (12 days from spawning) in
that stage. This is the last molt while the shrimp are in the
larval stages; they emerge from this metamorphosing molt as
post larvae.
Beginning at the first mysis stage, filtered sea water was
added daily over a 6- to 8-day period until the tank was at
maximum level of 2 meters.
The post larvae (P) are characterized by 5 pairs of pleo-
pods that function as appendages for swimming. The peri-
pods that served as swimming appendages in the mysis now
serve as grasping and walking appendages. The shrimp in
early stage become carnivorous and depend on Artemia nau-
plii and minced clam meat for food. Artemia eggs were
added at 500 to 1,000 grams/day/million P by Fujinaga.
A generalized feeding rate for minced clam meat is as follows:
Stage of P
P
4
-Po6
P -P - -
P1-lO -Pe
2
P
17
-Harvest
Weight of meat
per day per
million P
3 kg
6 kg
9 kg
12 kg
16 kg
Fujinaga stated that the amount of clam fed in his larval
production operations was less than half that given above.
The cost of Artemia eggs was 40,000 yen/kilogram ($50.00/
pound) and for clam meat 20 yen/kilogram ($0.03/pound).
It has been found that P in early stages each devour 46 to
84 Artemia nauplii in a 24-hour period. Body color of P
1 
(P
1
are 1st day post larvae; P
23 
would be 23rd day post larvae)
is colorless to whitish, but as Artemia are fed upon, body
color becomes red-orange, the color of Artemia nauplii.
Fujinaga expected 85 per cent survival of P shrimp from
P
1 
to harvest at P
20
-P
25
. Sea water was added daily during
the three mysis stages and up to the fourth day of the post-
larval stage to fill the tank from 0.7 meter to maximum depth
of 2 meters. From this point until shrimp were harvested,
sea water was added at a replacement rate of from 0.20 to
0.33 total volume/day. P
1 
shrimp are benthic, the first stage
to be so; therefore, until this stage is reached, replacing
water would result in loss of shrimp. Water temperature
12
from P
1 
stage onward was maintained at approximately 251
C. Generally, the P were harvested when they attained an
average of 0.01 to 0.02 gram and 15 to 20 millimeters length.
This was usually about P
20 
to P
25 
or 35 to 40 days after
stocking the brooders.
Harvest was not as difficult as it might appear. The col-
lecting facility on the outside end of the drain pipe was im-
portant in facilitating harvest. The contour of the tank floor,
permitting total drain of the tank, was also important. To
harvest, the first step was to drain the water level down to
about 0.4 meter. Fine mesh screens at the mouth of the
drain prevented loss of shrimp. Next, a plankton net about
2 meters long was affixed to the outside end of the drain.
The free end of the net was equipped with a draw string
to facilitate emptying collected shrimp. The screens on the
inside were removed and shrimp were allowed to pass through
the drain to be collected in the plankton net. Rate of flow
was controlled to prevent injury to shrimp. Also, the col-
lecting portion of the net was kept under water at all times
to prevent injury and stress. Shrimp collected in the net
were transferred to buckets as necessary.
The standard method for transporting and shipping P
shrimp was in polyethylene bags containing oxygen and sea
water. The number P per bag depended, of course, on size
of bag, period of time required in bag, and method of trans-
port (temperature control). An example would be to place
5,000 P in a 20-liter bag containing 8 liters of sea water;
add 10 liters of oxygen; place bag in metal or wood box;
add ice to top or place in a refrigerated hauling facility;
transport at approximately 120 C. Fujinaga shipped P
10 
to
France by air in this manner. Transport time was about
96 hours with only 10 per cent mortality.
Temperature acclimation is necessary but it evidently is
not as critical with shrimp as with fishes. Fujinaga some-
times acclimated P from 25' to 120 C in only 10 minutes.
Yields of P larvae are influenced by many factors, but
expectations of 25,000 per female or 5,000/cubic meter of
tank are realistic. Fujinaga averaged about 1 million per
200-cubic meter tank or 5,000/cubic meter.
Fujinaga expected to produce 60 million juvenile shrimp
per year with a total labor force of 5 people. He had the
capability of that production, but markets for P shrimp were
limited. Markets and outlets for P shrimp included private
shrimp farms, limited markets in other countries, and the nat-
ural waters of Japan. Private shrimp farms in Japan total about
100 hectares. At stocking densities of 250,000 to 350,000
P/hectare (25 to 35 P/square meter) there is need for only
25 to 35 million P to satisfy the demand for farm culture.
Some farmers of food-size shrimp produce their own P for
stocking. Foreign markets must necessarily be very small
due to the cost and problems in shipping. By far the major
outlet for shrimp is in the natural waters. An example of
this is that 5 propagation centers of the Nansei Regional
Fisheries Laboratory plan to release a collective total of
140 million shrimp into the Seto Inland Sea this year. Other
government-financed stations and cooperatives have similar
programs.
Production of Food Shrimp. The raising of food-size
shrimp from juveniles is not a large practice by any means.
The largest of the 14 food shrimp farms in Japan had 6 ponds
totaling 20 hectares. Two major factors limiting growth are
limited technology and profit risks. These and other prob-
lems in shrimp farming will be discussed in detail at the
end of this report.
Culture ponds have for the most part been converted from
abandoned salt fields where salt was obtained from sun-
evaporated sea water. Pond sizes ranged from less than 1
hectare up to 10 hectares. A convenient size was about 3
hectares with depths fluctuating between 1.0 and 1.5 meters
between low and high tides. Changing tides were utilized
to exchange water in the ponds. Gates with screens to re-
strict wild fish entry and shrimp escape were most frequently
used, but siphons emptying into screened boxes were also
used. Pond bottoms of sand were preferred, partially to ac-
commodate the burrowing habit of shrimp. Inside slopes
of dykes were usually lined with concrete. Suspended net
cages were being used experimentally to raise food shrimp.
Results thus far indicate that this may be a feasible method.
Preparation of the culture pond was necessary before stock-
ing. The pond was drained and dried, and any potholes re-
maining were poisoned with rotenone or tea-seed cake to
eradicate any fish that might be there. The bottom sand was
plowed at least once and new sand added if necessary. Any
necessary repairs were made on the facility before filling
with sea water. The pond should be prepared for stocking
by late April. Shrimp P may be stocked in a nursery pond
to raise them to juvenile stage before stocking into production
ponds for growing to food size. However, the nursery is not
necessary and P may be stocked directly into production
ponds. The latter alternative will be emphasized here.
The generalized system of raising food shrimp was stocking
ponds in May; feeding daily; and harvesting in October.
The P were stocked into production ponds from early May
to mid-June. Mean water temperature during this period
was about 150 C. Care was taken to stock the total number
of P so as to get even dispersal over the pond. Stocking
density was approximately 30 to 35 P/square meter of water.
Expected mortality was about 40 per cent during the culture
period, so with the above density about 20 shrimp/square
meter were expected at harvest. Mortalities result from
predation, disease, poor water quality, cannibalism, and other
causes; therefore, predicting a given per cent mortality is
hardly realistic. Quality management was probably reflected
more here than with most aquacultures. As a general rule,
the larger the shrimp when stocked the better the survival,
regardless of the duration of the culture.
The feeds used for shrimp culture were primarily clams
(i.e., Venerupis philippinarum and Mytilus edulis), shrimp,
fish (sand eel and horse mackerel), and occasionally squid
and flesh of other animals. The feeds were usually minced
or ground in preparation for feeding. Clams presented a
problem in that their flesh was difficult to obtain efficiently
and economically without some shell contamination. Con-
tinuous feeding of minced clam contaminated with bits of
shells resulted in undesirable hardening of the pond bottom.
The following table is an example of a feeding program
for shrimp being raised in production ponds from 0.1 gram
to food size (20 to 25 grams):
Shrimp size Feeding rate
Grams Pct. body wt. Times/day
0.1-0.5 ------
0.5-1.0---
1.0-5.0 ------
5.0-15.0----
15.0-25.0-
Type of feed
50 2 to 3 minced clam, shrimp
35 1 to 2 minced clam, shrimp
ground clam, fish,
25 1 small shrimp
ground clam, fish,
15 1 small shrimp
ground clam, fish,
5 1 small shrimp
The S conversion (kilograms of feed required to produce
1 kilogram of shrimp under pond conditions) usually was
13
from 10 to 15 following the above program. This is about
twice the conversion rate expected for most fish; however,
the loss of energy and prctein in the molting (ecdysis) proc-
ess of shrimp should alone account for a significant portion
of the differential in S between shrimp and fish.
The shrimp should be fed in late afternoon or early
evening. After they are about 0.1 gram in size, they feed
only at night. Movement of shrimp during daylight periods
is indicative of insufficient food or a stress condition. Can-
nibalism is also indicative of inadequate food quality or
quantity.
The most rapid growth of shrimp in ponds is from July
through September when water temperatures range from 230
to 280 C. Optimum temperature for growth is considered to
be about 25' C. At temperatures below 10
? 
C shrimp will
not take 
feed.
Maintaining suitable water quality is a greater problem in
shrimp ponds than in fish culture ponds because of the higher
oxygen requirement of the shrimp. The exclusive daily
feeding of ground or minced animal flesh tends to pollute
and lower water quality. However, the partial water ex-
change in the ponds by tidal activity flushes much of the
pollution out of the ponds, thus tending to improve water
quality. Kuruma shrimp by nature inhabit the pond bottom,
which is most likely to have water of poorest quality. To
maintain a high dissolved oxygen level at all depths of water,
paddle-wheel agitators were often employed.
Predatory and competitive fishes contaminate most culture
ponds, but apparently no attempts were made to eradicate
them. The practice of using tea-seed cake as a selective
piscicide was not used in Japan (tea-seed cake at 2.5 to
10.0 p.p.m. was used in Taiwan to selectively eradicate fish
without harm to shrimp; tolerance for the toxin was 50 times
greater in shrimp than in fish). Rotenone and RADA (rosin-
amine-D-acetate) have potential use as selective piscicides;
however, these materials are toxic to shrimp at lower con-
centrations and the margin of safety is not as great as with
tea-seed cake.
Disease was apparently not as serious a problem in Kuruma
shrimp culture as it was with most fish cultures. Shrimp are
cannibalistic, which becomes a significant factor as density
is increased; however, cannibalism is not considered a serious
problem when the shrimp are being fed properly. Cannibal-
ism occurs when shrimp are molting, at which time they are
soft and vulnerable to other shrimp, and probably also when
shrimp are sick.
The standard harvest methods required two kinds of gear:
pound nets and drag nets equipped with pumps. The pound
net was normally used in October and November, and the
continued harvest was by drag net.
The pound net, illustrated in Figure 10, is most effective
at night when the shrimp are active. However, catch with
this gear decreases with decreasing temperature because
shrimp become less active. It is then necessary to change
to the pump-drag net gear. The pump-drag net, Figure 11,
is operated disring the day. The drag net is towed along the
pond bottom behind a boat. A pump in the boat forces
water through a hose to a pipe positioned at the mouth of
the drag net. The water escapes downward from a series
of outlets in the pipe. The velocity of escaping water stirs
the sand, dislodging and frightening the shrimp to where
they can be collected in the trailing drag net.
Harvested shrimp must be kept alive and were immedi-
ately transferred to holding tanks equipped with aerators and
cooling coils. Water temperature was lowered to 12
?
to
FIG. 10. Pound net used to harvest cultured shrimp. A-body of net;
B-funnel traps; C-nchor lines; D-wing net; and E-pond dike.
FIG. 11. Pump-drag net. a-perforated pipe; b-pipe hose leading to
pump in boat; c-frame; d-drag net bag; e-tow lines; and f-frame
skids.
14
? 
C if it was not already that low. The low temperature
served three purposes: 1) prevented molting and subse-
quent cannibalism; 2) reduced shrimp metabolic rate; and,
3) caused a reddish tinge on appendages and other portions
of the shrimp desired for marketing. Shrimp were held in
this manner for at least 8 hours before being packed for
shipping. For shipping the shrimp were packed in boxes
containing dry sawdust. The packing was done in a cold-
room. A sawdust of coarse texture was used for packing.
Corrugated cardboard boxes with 31 x 27 x 15-centimeter
dimensions received a layer of sawdust followed by a layer
of shrimp, and so on until full. About 2.5 kilograms of
14
Meter
E
o i ty 3
i i ! I
nate most culture
shrimp graded to size were packed per box in warm weather
and 3.0 kilograms/box in winter. The shrimp had to be
alive when they reached their destination in Tokyo, Osaka,
or other cities.
The price for live shrimp at the Tokyo Central Fish Market
fluctuated according to availability from 2,500 to 11,000
yen/kilogram ($3.16 to $14.00/pound) with an annual aver-
age of about 3,500 to 4,000 yen/kilogram ($5.00/pound).
The highest paid price of 11,000 yen/kilogram was realized
only in April when shrimp were scarce.
At present it appears that the average price will steadily
increase in the next few years since the supply of naturally
produced shrimp has declined in recent years and is expected
to continue to do so.
Production costs were considered to average about 2,500
yen/kilogram ($3.16/pound) excluding depreciation on
ponds and other facilities. The following is a breakdown on
cost by item per kilogram of shrimp produced:
Cost Item
Labor
Feed-
Packing/shipping
Supplies, etc.
Interest
Totals-
Yen
540
1,080
540
180
180
2,520
Cost/kg
Dollars
1.5
3.0
1.5
0.5
0.5
7.0
Problems Associated with Shrimp Culture. The following
paragraphs contain personal observations and comments con-
cerning the problems associated with the culture of penaeid
shrimp in general and P. japonicus in particular. The dis-
cussion is concerned primarily on how these problems will
likely influence the future of shrimp culture in Japan and
the world. Discussion covers both the post larval and food
production phase of shrimp farming.
The high cost of production is perhaps the most significant
of all the problems associated with shrimp farming. Farm-
raised shrimp are definitely in the luxury food class. Ob-
viously, the product must bring a premium price to be an
economical venture for the farmers. The decline in supply
of naturally-produced shrimp is likely to increase the demand
and price of the cultured product.
As this occurs and profits increase accordingly, farming
operations may expand and new ones originate. However,
present cultural techniques limit expansion. For instance,
one feed item is fishes, which themselves are limited in
supply, and shrimp farmers must compete with eel farmers
and farmers of other fishes for trash fish for feed. The catch
per unit effort of trash fish is declining so it appears that
with the increasing demand and decreasing supply of these
fishes, production costs of farm-raised shrimp will necessarily
increase.
It is not conceivable that intensive monoculture shrimp
farming can be practiced on a profitable scale outside Japan
using present techniques with the resulting high cost of
production. For example, consider the possibilities of com-
mercial food shrimp culture in the United States using tech-
niques employed in Japan for Kuruma shrimp culture. Labor,
land, and construction cost would be more costly also. Suit-
able topography, soil, tidal fluctuations, and climate are
limited to very few areas of the United States. Nevertheless,
the principal limiting factor would be a low market price as
the United States shrimp farmer probably could not sell
his product for much over $1.50/pound.
The cost of production exceeds the market price in most
areas of the world where live shrimp do not command a
premium price. Cost of production in terms of protein pro-
hibits such an enterprise in most developing countries, where
it would be difficult to justify S conversions of 10 to 15 when
feeding animal meat exclusively.
Many of the problems indicated above center around the
use of animal flesh as feed. There are many obvious advan-
tages of artificial pelleted feeds over raw flesh; the most
important of which is simply that pelleted feeds are generally
cheaper and much more practical. Although research is
in progress on this problem, artificial feeds have not yet
been developed that are acceptable to the Kuruma shrimp,
either in the larval or adult stage. Even on highly fortified
pelleted feed, shrimp will probably not be as efficient in
conversion as most fish species. A great deal of energy and
protein are lost by shrimp when molting and in production
of its chitinous exoskeleton.
Production potential in shrimp culture ponds with tidal
water exchanges was reported to be not above 2.5 tons
hectare (2,300 pounds/acre) with the present techniques.
The factor limiting production is poor water quality result-
ing primarily from residues from the ground flesh feed. Pollu-
tion could be reduced through use of artificial feeds which
would have the effect of increasing production potential. The
methods of harvesting Kuruma shrimp now employed are
slow, laborious, and expensive. Harvest is complicated by
the habit of the shrimp to burrow. There is definite need
for improved harvesting techniques.
DISCUSSION
It appears Japan is faced with some serious problems in
most of its aquacultures. Few of the many methods of cul-
ture developed there have application in other countries. If
present methods are continued in Japan, many cultures will
have limited growth and some may actually decline.
Perhaps the most serious of all the problems, and perhaps
the ultimate limiting factor in the healthy growth of most
aquacultures in Japan, is the cost of production. It is now
the factor restricting many cultural practices to Japan. An
example of higher cost culture is that of the Kuruma shrimp.
The average cost to produce a kilogram of food size shrimp
is $7.00, or about $3.20/pound. This is acceptable in Japan
where the market prices for live cultured shrimp range from
$7.00 to $30.00/kilogram ($3.16 to $14.00/pound). Shrimp
farming at production costs of $3.50/pound has practically
no application outside of Japan.
The two primary cost items of all cultures are feed and
labor. Problems of labor scarcity and high labor costs are
being felt in Japan now and are expected to increase in
the future. Feed costs are expected to increase also, es-
pecially for those cultures requiring fresh meat as feed. The
supply of trash fish, the primary meat source, is decreasing
while the demand increases- a healthy situation only for the
feed supplier. The cost for trash fish was 30 yen/kilogram
($0.04/pound), while S conversions ranged from about 6
to 15. This represents a feed cost ranging from 180 to 450
yen/kilogram ($0.23 to $0.57/pound).
The costs of feed could be reduced in some cultures if
artificial feeds could be used, but many of the cultured ani-
mals are strict carnivores and attempts to feed artificial feeds
have met with little or no success.
5
. One researcher con-
However, in the United States piscivorous species such as the
largemouth bass have been reared on pelleted feeds after sub-
jecting the fish to a training period.
15
eluded that if yellowtail could be fed an artificial diet, at
least 70 per cent of the feed would have to consist of fish
meal. This requirement would preclude the development
of cheaper feeds.
Production has been considered from a monetary stand-
point, but production from a protein-efficiency standpoint is
also very important. It would be difficult in most countries
to justify such inefficient conversions of animal protein (S
6 to 15 using animal flesh). Solutions may be difficult o
find. The cultured animals must give efficient conversions
on prepared feeds that derive a large portion of their protein
from plants. Otherwise, these animals may become too
costly in terms of money and/or protein to culture on a
commercial basis.
Pollution is a problem of significance facing aquaculture
in Japan. The natural waters in many areas, especially
around large cities, are highly polluted. This is affecting
culturists in at least three ways. First, it restricts the use of
that water for filling ponds or for suspending culture cages
or rafts. Second, it is reducing the availability of young
animals for stocking because many must be obtained from
natural populations. Third, most culturists depend on trash
fish for feed and pollution is reducing local stocks, resulting
in less catch per unit of effort to the fishermen who must in-
crease effort or fish farther away from port.
Pollution results from an aquaculture system, especially
one under intensive feeding. Pollution is a much greater
problem when ground trash fish are used rather than pelleted
artificial feeds. The major results of pollution are increased
incidence of disease, lower carrying capacities of the culture
environment, and fish kills.
Still a major problem with many aquacultures in Japan,
as well as elsewhere, is that of having to depend on natural
populations for young animals for stocking. For some cul-
tures, the adults are collected from natural populations, while
spawning, hatching, and raising of young to a stockable size
are done artificially. For others, such as eel and oyster, the
young are collected directly from natural waters. Obviously,
no genetic improvement of the cultured animals 
is possible
under either of these conditions.
Another consideration is the decline in abundance of brood
or young in the natural populations. As an example, the
abundance of eel elvers for stocking has declined steadily
over the past few years. As a result, eel farmers are im-
porting elvers from countries such as Taiwan and France.
From the latter, elvers of different species have been im-
ported, and apparently have brought with them at least one
disease to which the Japanese eel is susceptible.
A potential disease problem innate in Japanese methods
of aquaculture results from the feeding of uncooked or other-
wise untreated trash fish. The transfer of disease organisms
through the feeding of raw fish has caused such severe dis-
ease problems in trout that many farmers in the United
States and Europe were forced out of production. This
problem has manifested itself in yellowtail culture.
Stocking programs, whereby young organisms are stocked
in natural waters to replenish natural stocks, are practiced
in Japan on a very large scale by various governmental agen-
cies and fisheries cooperatives. As an example, Nansei Re-
gional Fisheries Laboratory plans to release 140 million
young shrimp into the Seto Inland Sea this year from its
five propagational centers. Other organizations have similar
plans. Each prefecture receives a quota of young shrimp and
has responsibility for the actual release. This stocking pro-
gram has been in operation for a number of years, but no
studies have been made to determine its effectiveness.
Currently, much effort, facility, and money are being put
forth to artificially reproduce yellowfin and other tuna for
release into the Pacific Ocean. The objective is to replenish
the declining fishery. One researcher concluded that for
good survival the young fish should be at least 20 centi-
meters total length before stocking. This would suggest that
if this species can be efficiently raised to 20 centimeters,
the tuna should not be released but processed for food
directly or cultured to a larger size before processing. It is
difficult to comprehend a facility of the size necessary to
produce enough tuna 20 centimeters long to stock into the
Pacific Ocean to significantly affect the number of harvest-
able size tuna. The actual cost of culture would be phe-
nomenal since trash fish would probably be the feed ma-
terial. This would further increase the competitionfor trash
fish.
Experiences by various state and federal agencies in the
United States have demonstrated that replenishing breeding
populations of fishes in inland waters is a costly waste of
time and effort. Also, fishery biologists have learned that
fecundity in general varies inversely with the number of
parents. If this is the case in Pacific tuna, then the declining
adult population should be producing a greater than normal
number of offspring and replenishing may be unnecessay.
FACILITIES VISITED
Those places visited during this survey and general in-
formation on each are presented below in sequence visited.
The location of each is shown in Figure 12 and is indicated
by the corresponding brackets-enclosed numbers.
(1) Freshwater Fisheries Research Laboratory,
Dr. J. Yamakaya, Director,
Hino-shi, Tokyo, (May 17)
This is the only national institute engaged in research on
the culture of freshwater fishes. The institute is, however,
tri-divided with Hino serving as headquarters; one branch
is at Nikko, and the other at Ueda. Total area of research
ponds at all three locations is 14,750 square meters. Research
interest includes fish breeding, culture of exotic fishes, nutri-
tional requirements, feed production and testing,_production
of forage organisms, and diseases. Fishes being studied in-
clude eel, ayu, rainbow trout, common carp, and tilapias
(T. mossambica and T. nilotica). The station also produces
fish fry for sale to fish farmers.
(2) Kanagawa Prefecture Fisheries Experimental Station,
Mr. Masaaki Inoue, Chief, Culture Division,
Misaki, Miura, (May 18)
Primary functions of this station are research and exten-
sion in offshore fisheries. The station has seven divisions,
namely: 1) Culture (Propagaticn); 2) Offshore Coastal Te-
source (Population Dynamics); 3) Fish Management; 4)
Commercial Gear; 5) Oceanography; 6) Fry Production;
and, 7) Extension. Each division has six scientists. Also,
there are two branch stations each with 12 scientists. This
is a large, well-equipped and well-staffed station.
Culture animals being studied include sea bream, fiaffish,
abalone, and top-shell crab.
(3) Fujinaga Shrimp Farm,
Mr. Isamu Ando, Chief Biologist,
Yoshiki-gun, Yamaguchi-ken, (May 19)
This farmn is located on Aiu Bay. The hatchery consists
16
FIG. 12. Map of Honshu Island, Japan, showing aquacultural facilities
visited.
of 12 concrete tanks enclosed inside a large corrugated fiber-
glass building. The tanks are each 2 meters deep and 10
meters square. They are used for hatching and raising
shrimp to the post larval or stocking stage. Production po-
tential is 1 million post larvae/tank/40 to 50-day period.
Some research is also conducted at this facility. Individual
air and water supplies service each tank. The water is
heated when necessary. To preserve heat, the tanks were
constructed below ground level. The farm also includes
ponds and fenced-in areas of the bay that serve as produc-
tion ponds for raising post larval shrimp to marketable food
shrimp. The discussion of shrimp culture in this 
report covers
the system used at this farm.
(4) Yamaguchi Prefecture Culture Center,
Yoshiki-gun, Yamaguchi-ken, (May 19)
This station on Aiu Bay consists of 11 hectares of ponds.
Research interest is centered around shrimp, ayu, fungu, 
and
nori algae. Shrimp are reproduced here using the "Fujinaga
System," but in much smaller tanks than at the 
Fujinaga
Farm. Typical of the stations responsible for 
marine and
brackishwater organisms, this station is 
well equipped and
all facilities are modern and well kept.
(5) Nansei Regional Fisheries Laboratory,
Mr. S. Ota, Director,
Ohno-cho, Hiroshima-ken, (May 20)
This station has divisions of: 1) Research Planning 
and
Coordination; 2) Inland Sea Fisheries Resources 
Research;
3) Offshore Fisheries Resources Research; 4) Oceanographic
Research; 5) Aquaculture Research. 
The latter division con-
sists of four laboratories, namely: 1) Breeding 
Research; 2)
Nutritional and Physiological Research; 3) 
Pathological Re-
search; and, 4) Environmental Research. 
This division is
responsible for "restocking" the Seto Inland 
Sea fish popula-
tions. An example of the restocking program 
is that of the
shrimp releasing program. Under this program, five 
propa-
gation centers are expected to release 
140 million post larvae
shrimp into the Seto Inland Sea this year. 
No studies were
17
made prior to or after the initiation of the program a number
of years ago to measure effects of the releases. The first re-
leases were made directly into the sea but recent releases
have been into "naturalization" (conditioning) pens posi-
tioned in the sea. The young shrimp stay in the pens for 2
to 8 weeks before being finally released into the open sea.
Mortality here has been from 20 to 40 per cent. Other
cultures of interest here are those of porgy and oyster.
(6) Nichiro Gyogyo Oyster Plant,
Hiroshima-shi, (May 20)
This is the largest oyster plant in Japan and possibly the
world. Production of canned smoked oysters amounts to 20
million cans per year. All of these are exported. The Geisha
brand, familiar in the United States, is a product of Nichiro.
Most of these oysters are from raft cultures. In the Hiro-
shima area, approximately 30,000 tons of oyster meats are
produced per year in raft cultures.
(7) Pearl Research Laboratory,
Kashikojima, (May 22)
This station is totally engaged in support of the cultured
pearl industry. Their 11 research scientists are involved in
research to improve cultural methods, disease control, breed-
ing, physiology, mineralogy, and other aspects of the in-
dustry.
At present, there are 4,700 individual managements of
pearl culture that utilize 255,000 rafts. The annual value
of exported cultured pearls is in excess of $50 million.
(8) Fisheries Laboratory of Kinki University,
Dr. Teruo Harada, Professor,
Shirahama, (May 23)
This station is working with a large number of finfish and
oyster cultures. Dr. Harada began using floating net cages
in 1954 for raising yellowtail. The primary interest of this
station at present is tuna reproduction. Last year they were
successful in artificially spawning two female yellowfin, but
were unable to keep fry alive longer than 20 days.
Net cages are utilized for most work here with finfish.
Primary interest is on yellowtail and other Seriola sp., yel-
lowfin and bluefin tuna, oysters, and other fishes.
(9) Shizuoka Prefecture Fisheries Experimental Station,
Mr. Tsunogai, Director,
Hammatsu, (May 24)
This station is located adjacent to a laboratory of Tokyo
University. Research here covers both brackish and fresh-
water cultures. Oysters and norf are the primary brackish-
water cultures; eel, ayu, and carp are the freshwater species.
Eel, however, receives the major emphasis.
(10) Privately Owned Eel and Ayu Culturing Farms near
Hammatsu, (May 24)
Two farrns were visited where the owners were engaged
in the monoculturing of eel. Both farmers were using the
standard cultural methods discussed in this report. Both
farms were family operations which is apparently the case
with most eel farms.
A family-managed ayu culturing farm was also visited.
The elaborate facility and management techniques are dis-
cussed in this report under ayu culture. The owner of this
farm also processed and shipped his production.
(11) Eel Processing Plant near
Hammatsu, (May 24)
A plant engaged in processing and shipping eel was visited.
B~oth live and canned eel were shipped. The live eel were
shipped in oxygen-water filled plastic hags with approxi-
mately 10 kilograms of eel per hag. Markets for live eel
were primarily Osaka and Tokyo. Canned eel were in the
form of skinned, eviscerated sections approximately 4 inches
long, broiled and canned in soy sauce.
(12) Far Seas Fisheries Laboratory,
Dr. Yabuta, Director, Tokai University,
Shizuoka, (May 25)
This laboratory is concerned with pelagic fishes and off-
shore fish populations in general. The only culture in which
this station is interested is that of tuna, on which they are
cooperating with the Fisheries Laboratory of Kinki Univer-
sity. Their intention is to artificially reproduce species of
tuna for replenishing the natural ocean stocks.
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