THE IDENTIFICATION OF FISH EGGS AND LARVAE OBTAINED FROM THE SURVEY CRUISES I N THE

SOUTH CAINA SEA

S. Vatanachai Marine Fisheries Laboratory 89/1 Soi Sapan Pla, Yanawa Bangkok 12, Thailand

This paper presents the r e su l t s of the ident i f ica t ion of f i s h eggs and larvae which were obtained from ten survey c r u i ~ e s i n the South China Sea during the period January 1970 t o April 1971. A t o t a l of 4,959 f i s h larvae and 3,666 f i s h eggs was collected. They represented 137 species belonging t o 64 families and 21 unknown species; most of the f i s h eggs, however, remain unidentified.

The author gives br ief keys f o r the c l a s s i f i ca t ion of f i s h larvae found i n the South China Sea and also provides br ief descriptions of some eystematic character is t ics of l a rva l f i sh .

The information on the iden t i f i ca t ion of f i s h eggs and la rvae , especia l ly of those occurring i n the South China Sea i s still inadequate. Only Delsman (1921 - 1938) worked on the f i s h eggs and larvae of the ~ a v a Sea, but no publication i s so f a r avai lable on the material from the South China Sea, Recently, the author had the opportunity t o study the f i s h eggs and larvae material avai lable i n the southeast Asian Fisher ies Development Centreunder the guidance of D r S. Nito and D r T. Senta, s p e c i a l i s t s i n t h i s f i e l d . The publications of Deleman (1921 - 1938) and of Mito (1960 - 1966) on the iden t i f i ca t ion of f i s h eggs and larvae of t he Java Sea and Japan waters respect ive ly , were very useful sources of information.

I n t h i s paper the author presents t he r e s u l t s of i den t i f i ca t ion of f i s h eggs and larvae obtained from 10 survey cruises i n the South China Sea during the years of 1970 - 1971. Up t o the present I f 7 species of f i s h larvae belonging t o 64 fami l ies have been iden t i f i ed ; however, most of t he eggs remain unidentif ied. Alao, most of the larvae ,were 8-0 f a r i den t i f i ed only t o the genus and family l e v e l , but the author intends t o ca r ry out more de t a i l ed iden t i f i ca t ion i n the near future.

The author wishes t o express h i s gi.atitude t o D r Mito f o r giving permission t o use the da t a from the f i r s t 6 cPuises f o r the present study and f o r h i s he lpful advice, t o D r Senta f o r h i s encouragementland t o Yong Chong Teck f o r h i s int imate cooperation.

2. MATERIAL AND ITEIHOD

Fish eggs and larvae were col lec ted by using a l a rva l neD with a mouth opening of 1.3 m i n piame'ter and 4.5 m i n length. The ne t i t s e l f i s divided i n t o two par ts : t he an te r io r pa r t i s 3 m i n length with 3 mm mesh s i z e , whereas the pos ter ior pa r t i s 1.5 IV

i n length with very f i n e mesh (GG 38).

The area surveyed extended from lo t o 8 ' ~ l a t i t u d e and 101' t o 1 1 4 ' ~ 1ongitGde (Fig. 1 ) . Within the area 107 horizontal hauls were made during the period from Janu8r.y 1970 t o April 1971. With a few exceptions the horizontal t omof 10 minutes duration were car r ied out a t the surface and a t a speed of about 2 knots by the Reseal'ch Vesscl '

"Changi1I (386 gross tonnage). The col lec t ions were made i n day time a s well as night- time.

The f i s h eggs and larvae col lec ted were preserved. in 4 1 0 % formalin so lu t ion on board, together w i t h o ther plankton organisms. The samples were sorted i n the laboratory. The larvae were iden t i f i ed by genus or counted and measured.

During the survey period mentioned above, 4,959 f i s h la rvae and 5666 eggs were collected.

3.1 Fish enni and larvae collected

A l is t of eggs and larvae of f i s h col lec ted in the South China Sea during the I0 survey qruises i n 1970/71 is given below:

Individual Peak of Species Common name number * Occurrence*

Clupeidae (1-3) Clupea spp.

3erring , 347( 165) Nov., Apr. Sardines.

Dussumieridae Round herring, 9 Apr., Oct. (4) Cussumieria hasselti BLEEKER Sprat

Engraulidae (5) Engraulis spp. ( 6-7) Stolepholus spp.

Chirocentridae ( 8) ' Chirocentrus spp.

Synodontidae (9) Saurida tumbil (BLOCH) (10) Trachinocephalus myops

(FORSTER) ( 11) Synodus vaiegatus (LACDEDE)

Nyc t ophidae (12) Unknown spp.

Ophichthyidae (13) Unknown spp.

Apodes ( 14-16) Leptocephalus spp.

Belonidae (17) Ablennes spp. (18) Tylosurus spp. (19) Unknown spp.

Hemirhamphidae (20) IIemirhamphus spp. (21) Euletorhamphus longirostris

CUVIER

Exocoetidae (22-24) Cypselurus spp. (25) Prognichthys sp. (26) Hirundichthys ap. *(27-30) Unknown ep.

12. Bregmacerotidae (31) Bregmaceros sp.

13. Fistulariidae (32) Fistularia sp.

14. Syngnathidae (33) Syngnathus ap.

Anchovies 69(127) ~ct., (Apr.1

Dorab (2) (Oct .)

Lizzardfish 26( 5) 0ct.-Nov. ,(Oct.)

Lanternfish (2) (~pr.1

Snake eel 2 Oct .

Eel 15(26) hpr.,Jun.(Apr.)

Gar fish Feb.-Apr.

Half beak

Flying fish (154) May(Apr.-Oct .) 60 1

24 I94

Ankana cod Aug .

Cornet dish 10 Oct.

Pipe fish 1 Aug .

Holocentridae (34) Holocentrus sp.

Sphyraenidae (35) Sphyraena sp.

Mugilidae

(36) Hugil sp.

Atherinidae (37) Atherina sp.

Serranidae (38) Epinephelus sp.

Theraponidae ( 39-40} Therapon spp . Apogonid ae (41-42) Apogon spp.

S i l lagin idae (43) Si l lago sp,.

Carangidae (44) Chorinemus o r i e n t a l i s

TEMHINCK & SCIILEGEL (45-48) Caranx spp. (49-50) Ser io la spp . (51-55) Unknown SPP.

Menidae

(56) Mene maculata (BMCH & SCHNEIDER)

Coryphaenidae

(57) Corsphaena spp.

Lutianidae (58) Lutianus spp.

Lobotidae (59) Lobotes surinamensis (BLOCH)

Leiognathidae (60) Leiognathus spp.

Gerridae (61) Unknown sp.

Pomasyidae (62) Unknown sp.

Sc iaenidae (63) Unknown sp.

Soldier f i s h

Barracuda

Grey mullet

S i lvers ides

Grouper

Therapon

Cardinalf i s h

Vhi t i n g

Horse macker- e l s , jacks, Travelly

Moon f i s h , Razor t r ave l ly

Dolphin f i s h

Snapper

Triple t a i l

Pony f i s h

Silver- biddies

Grunters, Javel in f i s h

Riverking f i s h Jaw f i s h

Apr .

kpr., Aug.

May- Jun .

Apr., Aug.

Jan. ,Apr. ,Jun.

kpr., Jul .

Jun. -Aug .

Nov.

Apr. ,Nov. ,(Apr.)

Ju l .

May

Jun.-No~.

J u l .

Apr .

Jun.

Nov.

Nov .

Sparidae (64) Unknown sp.

S i lve r breams

Goat fish

12 hpr.

Mullidae

( 65-67) Upeneus spp.

Cepolas Cepolidae (68) Acanthocepola sp.

(69) Unknown sp.

Cul .

Apr.

Wov.

Pomacentridae (70) Un7xnown sp.

Anemone f i s h

Clown f i s h Amphiprionidae (71) Unknown sp.

Labridae (72) Aovaculichthys sp. (73) Unknown sp.

Wrasses, Zain- bow f i s h

Aug .

Ju l .

J u l .

Opisthognathidae (74) Opisthognathus sg.

Jaw f i s h

Champsodontidae

(75) Champsodon sp.

Champsodons

Blenniidae (76) Xiphasia s e t i f e r SWAINSON (77) Dasson t rossulus

(JORDAN ET SNYDER) (78) Unknown sp.

Blennies

I)rago,nets

Rabbit f i s h

Nov. ,(Apr.)

Jan.-Apr.

Callionymidae (79-80) Callionymus spp.

Siganidae (81) Siganus sp.

Trichiuridae (82) Trichiurus sp.

Ribbon f i s h

Mackerel

(Nov.)

Apr . Scombridaa (83) Auxis sp. (84) Unknown sp.

Thunnidae (85-86) Unknown sp.

Tuna

Scomberomoridae (87) Scomberomorus sp.

Spanish mackerel

Aug .

Apr . -Hay Histiophoridae (88) Histiophorue sp. (89; Eumakaira n iger NAKAHURA

S a i l f i s h Marlin.

- 117 -

Stromateidae Pomf r e t s

(90) Parastromateus niger (BMCH) (91) Psenopsis sp.

3 Jun. 2 Feb. ,Apr.

Gobies 549 Apr., Oct. Gobiidae

(92-98) Unknom sp.

Gobies 9 Apr., Oct. Trypauchenidae (99) Unknown sp.

Scorpion f i s h 5 Ju l .

6 Nov . Fla t f i s h Platycephalidae (102) Platycephalus sp .

Flying Gurnard

Cephalac anthidae (103) Daicocus peterseni (NYSTROII) (104) Dectylopterus sp.

Apr . , Nov.

Bothidae (105) Arnoglossus

(106) Unknown sp.

Left handed flounder 9

34

Pleuronectidae

(107) Unknown sp.

Right handed

flounder 5

Soles Soleidae (108) Unknown sp. Oct.

Nov . Cynoglossidae

(109) Unknown sp.

Tongue f i s h

Echeneidae (110) Echenis sp.

Remoras, Shark suckers

Trigger f i s h Bal is t idae (111) Unknown sp.

Monac ant hid ae (112) unknown sp.

F i l e f i s h Apr .

Apr., Nov. Aluteridae (113) Stephanolepis sp.

F i l e f i s h

Box f i s h Jan.

Ju l .

Jan.

Ostraciidae (114) Unknown sp.

Tetraodontidae (115) Unknown sp.

Puffer f i s h

Dragon f i s h Pegasidae (116) Pegasus vol i tans L I W

Unknown ( I I 7-1 37) Unknown SP

* Oxyoorham~hus species is included (a) Number of eggs and. occurrence given i n brackets

3.2 How' t o iden t i fy the l a r v a l f i s h

The larvae of marine f i s h are usually pelagic, and such larvae are e a s i l y collected

by a l a r v a l net . However, the iden t i f i ca t ion of these larvae is not always easy, because many cha rac t e r i s t i c s which are available t o iden t i fy the adul t do not

d i f f e r e n t i a t e their l ama l ' s t ages . Therefore, specie1 kinds of keys are necessary f o r i den t i f i ca t ion of l a rva l f i sh .

The following cha rac t e r i s t i c s seem t o be available f o r sor t ing the l a rva l f i s h , i n t o

groups o r 'families; more de ta i led observhtions are needed fo r the iden t i f i ca t ion of

the species. Here, the author only gives b r i e f keys available f o r i den t i f i ca t ion of

fami l ies o r groups of f i s h larvae.

Body Shape

a, Body elongated;

body slender; Clupeidae, Dussumieridae, Engraulidae, Belonidae, Hemirhimphidae,

Syngnathidae, Atherinidae, Synodontidae, F i s tu l a r i i dae ,

Blenniidae.

body r a the r slender;

Sphyraenidae, S i l lagin idae , Mullidae, Bregmacerotidae, Cepolidae, Labridae, Histiopholidae, Gobiidae, Gerridae, Trypauchenidae,

Coryphaenidae, Cynoglosaidae.

spear l i k e body;

Belonidae , Hemirhamphidae . ribbon l i k e body;

Apodes, Ophichthyidae.

spindle l i k e ; Exocoetidae.

snake l i k e ; Bleniidae.

a2 Body shor t ; moderate shor t ; Mugilidae, Holocentridae, S e r r ~ i d a e , Theraponidae, Apogonidae,

Carangidae, Menidae, Lutianidae, Lobotidae, Leiognathidae, Pomadasyidae, Sciaenidae, Sparidae, Pomacentridae, Amphiprionidae,

Opisthognathidae, Thunnidae, Champsodontidae, Callionymidae, Siganidae, Scombridae, Scomberomoridae, Stromateidae,

Scorpaenidae , Platycephalieae , Cephalacanthidae . globular shape; Ostraciidae, Tetraodontidae.

oval shape; Monac,anthidae, Stromateidae, Bal is t idae , Aluteridae.

t r i angu la r shape; Menidae.

a3 Body deeply compressed;

Bothidae, Cynoglossidae, Pleuronectidae, Soleidae, Menidae.

ah Body s l i g h t l y depressed;

Platycephalidae, Pegasidae, Dactylopteridae.

Body s t r u c t u r e

bl body covered with bony s t r u c t u r e ; Syngnathidae, Pegasidae, Os t rac i idae , Dac ty lop te r idae .

b2 body encased with sp iny s c a l e : 3 a l i s t i d a e , Alu te r ieae , C e p h a l a c a ~ t h i d a e , 3 iodont idae ,

Tetraodontidae.

head with bony c r e s t on t k e nape; Lobotidae, Holocentr idae, C e ~ o l i d z e , Champsodontidae,

Leiognathidae (som s p e c i e s ) , Coryphaenidae, S igan idae ,

Platycephal idae . head with prominent sp ine ;

Holocentr idae, His t r iophor idae , ' O q . : i : l ocanLhlhae,

Dactylopter idae.

head w i t h p reopercu la r s p i r e s ; Holocentr idae, Theraponid-~e, :'-ir'x?l;idae, ' C o r ~ h e n i d a e ,

Scorrberornoridae, Hist iophori , ice . .:'hur:nid;ie, Lut ian idae , Zepolidae , Ser ran idae , Sigar-idse, Lohotidae, Apogonidae,

L e i o ~ n a t h i d a e , Yienidae, Sc ian ieae , S ~ s r i d a e , Champso-

dont idae , P la tycepha l idae , S c o r ~ a n n i d a e .

head without p reopercu la r sp ine ; Scombridae , LaSridae, Gobiidae, Tripauchenidae .

head wi th bony r i d g e above t h e eye; Sc iaen idae , Carargidae ( S e r i o l a sp. and Nancrates s p . ) ,

Scorpaenidae, Stromateidae, Cephalacanthidae, Cepolidae,

Holocentr idae, His t r iophor idae , Champsodontidae, S i ~ a n i d a e .

head wi th protruded snout ;

Holocentr idae, His t r iophor idae , Pegasid ae.

head w i t h protruded lower jaw; Hemirhamphidae, Belonidae, Exocoetidae.

presence of barbe l on lower Jaw; Exocoetidae.

presence of e longated t e n t a c l e on operculum; Champsodontidae .

Shape and p o s i t i o n of mouth

d l ob l ique ; Hemirhamphidae, Exocoetidae, Bregmacerotidae, hpognidae, Leiognathidae , Carangidae , Labridae , Lut ian idae , Ser ran iPae , Opisthognathidae.

d2 i n f e r i o r ; Holocentr ieae, Cephalacant i idae.

i L tuke l i k e rcouth; 3i s t u l a r i i d a e , Syngnathieae.

small mouth; '- 5 Lakr i tae , B a l i s t i d a e , Monacanthidae, Alutheridae, O s t r a c i i d a e ,

Tetraodontidae.

d5 wide no~?t:l; DussumieriCae, Ago<es, Sphyraenidae, ThunniCae, Scombero- noridae, ' His t iophor idee , F la tycepha l idae , Champsodohtidae,

Lut ianidae , S e r m n i d a e , Opisthognathidae.

two separated. d o r s a l f i n s ; Kugil idae, hpogonidae, I<ul l idse, Gobiidae, h t h e r i n i d a e ,

Cephalacanthidae.

one long d o r s a l f i n ; Bregmacerotidse , Ser ran ldae , Theraponid ae + PIenidae , Carangidae , Coryphaenidae, LutianiL?ae, Lokotidse, Leiognathidae, Gerr idae,

Pomacentridae, Labridae, Sciaenidae, Cepclidae, Blenni idae,

Opis thomafh idae , Thunnidae, His t iophor idae , Stromateidae,

Trypauchenidae, Bothidae, So le idae , P leuronec t idae ,

Synogl.ossidae.

b i g p e c t o r a l f i n s ; Exocoetidae, ScorpaeniBae, P la tycepha l idae , Cephalacanthidae.

b i g v e n t r a l f i n s ; 3xocoet idae, Stromateidae ( l a c k i n a d a l t ) , Callionymidae,

P la tycepha l idae , Champsodontidae.

v e 2 t r a l absen t ; lipodes , Syngnathidae, Tetraodontidae.

lower lobe of caudal f i n somewhat elongated;

Exocoetidae.

e longated f i n ray; Rothidae ( 1 s t d o r s a l r a y ) , So le idae ( 1 s t d o r s a l r a y ) ,

Cynoglossidae (two of t h e m t e r i o r d o r s a l r a y s ) , Bregma-

c e r o t i d a e , Cephalacmthidae (Dactylopterus sp.;.

e longated d o r s a l and v e n t r a l f i n sp ines ;

Lut ian idae , Ser ran idae , Siganidae, B a l i s t i d a e , Alu te r idse .

absence of csuds:L f i n ;

Ophichthyidae.

causal f i n w i t 3 e longated f i l ament ;

F i s t u l a r i i d a e .

P o s i t i o n of enus

f anus s i t u a t e d f a3. bxckward;

Clupeidae, Uus. .c~nier idae, 3ngra;llidae, Belonidae, Synodont;idae-.

f 2 l nus s i t u a t e d f a ? :c)rward;

!3re~;macero-tii! aq , P-therinidae , '.'r.vpauchenidae, b lenn i idae , (Xiphas ie setii ' ;!r).

annus s i tua t ed nearly middle of body; Holocentridae, Theraponidae, Apogonidae, Gobiidae, Larbridae,

S i l lagin idae , Sarrangidae, Mxllidae, Lutianidae, 'Phunnidae , ScorpaeniBae , Sepolidae , Opisthognathidae, Scomberomoridae , Coryphaenidae, Sparidae, Champsodontidae, Pleuronectidae,

Bothidae.

anus s i t ua t ed behind middle of body; Apodes, HemirhamphiCae, Exocoetidae, F i s tu l a r i i dae , Migilidae,

S ~ ~ y r a e n i d a e , CoryphaeniBae, Platycephalidae, Cephalacanthidae.

D i ~ e s t i v e t r a c t

g,, alimentary canal showed i n ve r t i ca l muscle strands; Clupeidae, Engraulidae, Dussumieridae, Synodontidae.

g2 abdominal bulging out l i ke a sac; Cynoglossidae, Soleidae.

Pigmentation

a l l the body dark i n colour; Holocentridae , Selonidae, Carangidae, ( ~ e r i o l a sp .) , Bal is t idae , Coryphaenidae , Blemiidae, Pegasidae, Histiophoridae, Cephalacanthidae.

some pa r t of body densely pigmented; Exocoetidae, Atherinidae, Theraponidae, I?ullidae, Apogonidae

(some member), Stromateidae, Lobotidae, Platycephalidae.

few pigments on the body; Engraulidae, Dussumieridae, Bregmacerotidae, Synodontidae,

Exocoetidae, Theraponidae, Apogonidae, Lutianidae, Menidae,

Serranidae, Leiognath53ae, Siganidae, Scomberoaoridae,

Thunnidae, Trypauchenidae, Pleuronectidae, Cynoglossidae,

-Gobiidae, Opisthognathidae.

almost wlthout pigment; Gobiidae, Trypauchenidae, Sothidae, Soleidae.

Msotome number

il numerous myotomes (more than 50); Synodontidae, .Apodes, Belonidae, Hemirhamphidae, Dussumieridae,

Cepolidae, Bregmacerotidae, Blemiidae , Cynoglossidae.

i2 somewhat numerous myotomes (30-50) ; Clupeidae, Engraulidae,, Exocoetidae, Atherinidae, l'hmnidae , Scomberomoridae, S i l lagin idae , Scombridae, Trypaucheniaae,

Gobiidae , Coryphaenidae . i j 24 myotomes; Mugillidae, Sphyraenidae, Carangidae, Gobiidae, Mullidae,

Histiophoridae, Theraponidae, Lobotidae, Leiognathidae, Serranidae, Lutianidae, Apogonidae, Sciaenidae, an& many others.

i4 l e s s than 24 nyotomes; Bal is t idae , :.luteridae, Honacanthidae, Tetraodonti&ae,

3.3 Some important cha rac t e r i s t i c s of f i s h larvae

The bes t way t o ca r ry out taxononical s tudies on l a r v a l f i s h i s t o iden t i fy a s e r i e s

of developmental s tages and t o 'race t h e i r morphological changes through smaller end s n a l l e r individuals. However, as fo r some species only one or a few larvae were col lec ted , the iden t i f i ca t ion to spec i f i c l eve l was not possible.

I n Clupeoid la rvae , especia l ly i n t h e i r ea r ly s tages , the d i f f e ren t i a t ion between Encrnulidae as8 Clupeidae is cu i t e d i f f i c u l t . The main differences between these two

famil ies are: (1) shape of the h e ~ d , (2 ) pos i t ion of nout!~, ( 3 ) number of pre-anal myotones, (4) r e l a t ive p o s i t i m of do-sal and anal f i n , (5) number of f i n rays, (6) pigmentation (Xg. 2).

The Engraulid larvae are characterised by the following fea tures : (1) head somewhat

round, mouth subterminal, (b) maxillary very long and extending bey0r.d the eye, (c) dorsal and anal f i n s overlapping or close together i n a s t r a i g h t l i ne . It is very d i f f i c u l t t o separate the genera Enxraulis and Stolephorus (Fig. 21, because the number of t h e i r pre-anal myotomes var ies from 24 t o 30 accor6ing t o developmental stages.

Tne larvae of Syrodontids are r a the r common, especia l ly i n October and November. There are a t l e a s t three species i n the South China Sea. A l l the laryae have an elongated body, the a i f ferences mong the species being the nuuber and pos i t ion of b ig round black-brown pigment spots, number of f i n r a p , and number of vertebrae and nyotomes (Pig. 7 ) .

The nost important character t o separate IIemirhm.phids from Belonids i s the myotome

number: 47-60 f o r Hemirhamphids and 40 f o r Belonids (Fig. 3).

The family Exocoetidae, includes nany species of f ly jng f i s h occurring i n the South Chins Sea. Generally, the genus Exocoetus has fan shaped pectoral f i n extending behind the vent ra l f i n s , which are usually r a the r small i n the post- larval stage (Fig. 4). The genus ",selurus has a pa i r of la rge vent ra l f i n s which extend t o the anal f i n ; ir,, some species the vent ra l f i n s extend fu r the r t o the or ig in of the caudal. Hirundichthys and Oxyporhamphus, have intermediate cha rac t e r i s t i c s of Cmselurus and Exocoetus. Parexocoetus has a pa i r of la rge vent ra l f i n s , but normally smaller than Cmselurus, and the o s t e r i o r pa r t of the dorsal f i n is elevated.

The Theraponidae larvae made up 2.88% of the t o t a l col lec t ion and occurred throughout the year i n coas te l waters. A t l e a s t two species are represented i n the collections: One species i s characterised by many pigments scattered a l l over the body, and by i t s resemblance with ku l l id larvae; the other with few pigments and s imi l a r t o those found around Japanese waters.

Carangid larvae were one of the most abundant f i s h i n the area. 413 individuals were col lec ted , representing 8.3% of the t o t a l col lec t ion . A t l e a s t 10 species of Carangid la rvae appeared i n surface layers . Their i den t i f ida t ion , in to species was car r ied out by observntions on the pigmentation during the developmental stages, number of f i n rajrs and spines, number of preopercular spines and pos i t ion of bony ridge o r bony c r e s t on ;he head, e tc . ( F i g . 7).

The genus Lutianus was one of t he most abundant i n trawl catches, but the larvae were seldom collected by the surface plankton tows. I n the col lec t ion only 8

larvae were found. It i s supposed t h a t they are not surface dwellers. The larva i s characterised by i t s big head and compressed body with elongated and ser ra ted

spines of dorsa l and vent ra l f i n s (Fig. 8).

The Serranid l a rva is more o r l e s s the same as the LutianiC l a rva i n appearance, both having elongated and ser ra ted spines i n dorsa l and vent ra l f i n s . The d i f ferences af la rvae between these two famil ies are: higher body i n Lutianid, d i f f e r e c t number of f i n rays, d i f f e ren t pigmentation pat tern and so on. The Serranid la rvae were rare i n the col lec t ions , only 5 specimens were col lec ted i n offshore waters.

The Mullid larvae were the most dominant i n our collection: 2,146 specimens were found, r e p r e s e n ~ i n g 43.9% of the wnole catc:?. Although they occurred throughvat the year the main spawning season seems t o be June whsn as mdny as 1,009 specimens

were caught. k t l e a s t 3 o r 4 species occurred i n the col lec t ion . The 2igmentation pa t t e rn and the number of f i n rays should be available f o r i den t i f i ca t ion of the la rvae (Fig. 9 ) .

The larvae of ScombroiB. f i s h were not very common i n the collectioris; among them

the Thunnid la rvae were more abundant than other groups. From June t o August 21 individuals were col lec ted i n offshore waters. Only one R a s t r e l l i ~ e r l a rva (2.5 mm) was collected i n April (Yig. 9). However, t h i s kind of larvae commonly appeared i n the Gulf of Thailand, especia l ly i n April an& August. It seems e i t h e r t h a t t h e i r s p a k i n g ground i s not i n the South China Sea, but i n the Gulf of Thailand o r t h a t the post larvae are d i s t r ibu te& a t mid layers i n the South China Sea. Another member of Scombroid la rvae , ScomberomoriC i s r a the r r a re i n the col lec t ions ; the main cha rac t e r i s t i c s t o iden t i fy these larvae are number of myotomes, appearance of preopercular spines, numker of f i n rays, the pigmentation pa t t e rn i n various developmental s tages , and so on.

The appearance of the Gobiid l a rva i s much more slender with two dorsal f i n s separated not f a r apear (Fig. 10). Soft dorsal and anal f i n s located opgosite and with nearly equal number of rays. I n l a rva l stage it can e a s i l y be 3istinguished by the existence of an a i r bladder above the abdominal par t . About 7 species were separated. The Gobiid larvae were among the most abundant following the Kullid larvae i n the col lec t ions . A t o t a l of 549 individuals were col lec ted , and a s 282 individuals were caught i n November, the author presumes tha: t h i s month might

be t h e i r main spawning season.

F l a t f i s h l a rvae are e a s i l y dist inguished by t h e i r extreaely compressed and somewnat elongated body (Fig. 11). The dorsal f i n or ig inates f a r for74ard on the top of the head and continues t o the caudal. The Corsal and anal f i n s are separated from the caudal f i n i n the larvae belonging t o the fami l ies Bothidae and Pleuronectidae. I n some of t he la rvae belonging t o the family Soleidae, these th ree f i n s are fused together a s found i n the genus C ~ o ~ l o s s u s . Other cha rac t e r i s t i c s f o r c lose r i d e n t i f i c a t i o n of these larvae a re as follows: (a) the nuzber of f i n rays, (b) number of myotomes, (c) pigmentation such a s seen i n one of t he Pleuronectidae la rvae which has 9 blotches of rhodophores on the dorsal from the i n t e r o r b i t a l t o the caudal, (d) the existence of elongated dorsa l rays which were eas i ly broken during the col lec t ion .

Only one larva of t r igger f i s h was collected ( i n November), whereas, the adult f i s h (Abalistes s t e l l a t u s Bleeker) i s one of the most abundant f i s h in trawl catches i n the South China Sea. A t the 1ength.of 16.5 mm, trle body was encased already with spiny scales. The dtrong and serrated dorsal spines were situated behind the nape and the ventral spine was prominent. The melanophores were dis t r ibuted densely on the whole body, especially a t the ventral and caudal region.

The ident i f icat ion of the Priacanthid (big-eyed snapper) and Bemipterid larvae (threadfin breams), which are widely dis t r ibuted i n the South China Sea, is not yet possible.

Some examples of f i s h larvae are shown i n Figs. 2 - 11.

4. SUMMARY

During the period from January 1970 t o April 1971, 10 survey cruise8 were made in the South China Sea, and a t o t a l of 4959 f i s h larvae and 7666 f i s h eggs w'ere collected. The

l a rva l material was ident i f ied by family, genus,or species: 137 species belonging t o 64 families and 21 unknown species have been identified.

The most dominant larval f i s h was Mullid which occupied 43.9% of the whole l a rva l catch,

followed by Gobioid ??.I%, Cl.upeoid 8.4:6, Carangoid 8.3%, Exocoetid 4.676, Theraponid 2.9%,

Synodontid 2.2%, others I3.2%,and unknown 5.4%.

A key f o r c lasai r icat ion of f i s h larvae founii i n the South China Sea i n t o taxonomic groups or families i s given as well as brief descriptions of some systematic character is t ics of the l a rva l f ishing group fo r the sake of a closer ident i f icct ion.

Boonprakob , U. , The ident i f icat ion of pelagic eggs and larvae o f chub mackerel,

1965 R a s t r e l l i ~ e r spp. i n the Gulf of Thailand with additional study on t h e i r distribution. Dept. of Fish., Bangkok. Lar. Fish. Lab., Contrib. No. 4, 115-151

Delsman, H.C., 'l921-38

Hattori , S.,

I9W

Matsui, T.,

1963

Mito, s., 1960

Fish eggs and larvae from the Java Sea, 1-24 Treubia 2(1), 97-108;

5(4) , 408-418; 6(3,4), 297-307; 8( 3,4), 199-218; 394) 278-239;

8(3,4), 395-399; 8(3,4), 400-412; 9(4), 338-351 ; 11 (21, 275-286; 12(3,4)., 367-370; 1 3(2), 217-243; l3( 3,4), 401-409; 14(2) ,237-254;

16( 3) , 41 5-420

Studies on Fish Larvae i n the Kuroshio and Adjacent Waters.

Bull. Tokai R ~ R . Fish. Res. Lab., 40 : 1-58

The larvae of R a s t r e l l i ~ e r . Ecology of the Gulf of Thailand an5 the South China Sea. A report on the resu l t s of the NAGA

Expedition, 1959-1961. South-east Asia Research Programme, University of California, S c r i m s I n s t i t . Gceano~r., La J o l l a , California. SIO Reference 63-6 : 59-69

Key t o the pelagic f i s h eggs and hatched larvae found i n the adjacent waters of Japan. Sci. Bull. Fac. A ~ r i c . Kmshu Univ., 18(1),

71-94

Mito, S., 1961

Senta, T.,

1.962

Wat anachai , S. , 1970

Vijaysraghavan, P.,

1957

Pelagic f i s h eggs from Japanese waters - I. qlupeina, Chanina, Stomiana, Myctophida, Anguillida, Belonida, and S$ngnathidae.

u., l8(3) , 285-310

Pelaeic f i s h eggs from Japanese water - 11. Lamprida, Belonida, Zeida, Mugilina, Scombrina, Carangina, and Stromateina. w., 18(4), 451-466

Pelagic f i s h eggs from Japanese waters - IV. Traahinina and

Uranoscopina. I_bid., 19(3), 369-376

Pelagic f i s h eggs from Japanese waters - V. Callionymina and

Ophidiina. w., , l9( 31, 777-380

Pelagic f i s h eggs from Japanese waters - V I . Labrina. u., 19(4) 493-502

Pelagic f i s h eggs from Japanese,waters - V I I . Chaetodontina, Bal is t ina , and bstraciontina. x., I9(4) , 503-506

Pelagic f i s h eggs from Japanese waters - 111. Percina, Japanese Journ. Ichthyol., l'l(1-2) : 39-64

Pelagic f i s h eggs from Japanese waters - V I I I . Cottina. m., 3-61 , 65-79

Pelagic f i s h eggs from Japanese, waters - I X . Scheneida and

Pleuronectida. m., 11( 5-61 , 81-102

Pelagic f i s h eggs' from Japanese waters - X. Gadida and Lophiida.

m., 11[3-6), 103-113

'Fish eggs and larvae. Soyo. sha, Tokyo. No. 7, 1-74, 26 p l s .

Some Ecological notes on the Planktonic Fish larvae. Information Bul le t in on Planktology i n Japan. 14, 33-49

Studies on occurrence of eggs and larvae of f i s h i n adjacent waters t o the Oki Island. I. The species occurred. Japanese Journal of Ecolonr. 12(4), 152-157

Ibid. 11. The seasgnal abundance. u., 12(5), 163-166. -

Study on the d i s t r ibu t ion of eggs and larvae of f i s h i n the

adjacent waters t o westsrn Japan. Bull. Fish. 3xp. Sta t . , Okayama Pref. , 1-80

Results of the Ras t r e l l i ne r spp.'s spawning period and spawning ground surveys off the western coast of the Gulf of Thailand. 38 pp, (unpublished, i n Thai).

Studies on-Fish Eggs and Larvae of Madras Coast. Thesis submit- ted t o the University of Madras f o r the Degree of Doctor of

Fhilosophy. 79 pp.