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Species of Rastrelliger in the Java Sea, their taxonomy, morphometry and population dynamics Sudjastani, Tatang 1974

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\  c THE SPECIES OF RASTRELLIGER  IN THE JAVA SEA, THEIR  TAXONOMY, MORPHOMETRY AND POPULATION DYNAMICS  by  TATANG SUDJASTANI B.Sc.  Academy of Agriculture  Bogor, Indonesia, 1962  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in the Department of Zoology We accept this thesis as conforming to the required standard  The University of B r i t i s h Columbia A p r i l , 1974  In p r e s e n t i n g t h i s t h e s i s  i n p a r t i a l f u l f i l m e n t of the requirements  an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e  for  I agree t h a t and s t u d y .  copying o f t h i s  thesis  f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . of t h i s t h e s i s  It  i s understood t h a t copying or p u b l i c a t i o n  f o r f i n a n c i a l g a i n s h a l l not be allowed without my  written permission.  Department of  ZOOLOGY  The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada  Date  9  APRIL 1974  ABSTRACT Rastrelliger  i s a mackerel genus which i n h a b i t s the Indo-  P a c i f i c Regions. T h i s genus i s c h a r a c t e r i z e d by l o n g , numerous and f e a t h e r l i k e g i l l r a k e r s , and anal f i n without s p i n e s . Two s p e c i e s , Rastrelliger  braahysoma  and R. kanagurta,  a r e recognized. These are  i d e n t i f i e d by the d i f f e r e n c e s i n the r a t i o s o f the g r e a t e s t body depth and the length o f i n t e s t i n e to f o r k l e n g t h , and the appearance of the c e p h a l i c l a t e r a l l i n e canal systems. Synonymies, d e s c r i p t i o n s and morphometric ranges are g i v e n . The morphometric c h a r a c t e r s o f the two s p e c i e s e x h i b i t some i n t r a s p e c i f i c d i f f e r e n c e s due t o sexual dimorphism and strong a l l o m e t r i c growth,  R.  braahysoma  e x h i b i t s i n t r a s p e c i f i c geographical  v a r i a t i o n i n i t s d o r s o v e n t r a l depth, g r e a t e s t body depth, and i n t e r o r b i t a l d i s t a n c e ; while  R.  kanagurta  e x h i b i t s v a r i a t i o n only i n i t s  d o r s o v e n t r a l depth and head depth. Both speci.es a t t a i n t h e i r maximum growth increments  before  they reach sexual m a t u r i t y . The v i t a l parameters f o r y i e l d p r e d i c t i o n a r e as f o l l o w s : the c o e f f i c i e n t o f growth r a t e K=0.19, 0.23; the length-weight exponent b=2.88, 3.19; the maximum length 1.^=22.92 cm, 23.89 cm; the natural m o r t a l i t y c o e f f i c i e n t M=0.38, 0.37; and t h e t o t a l m o r t a l i t y coefficient  Z=0.82, 1.20 f o r i ? , braahysoma  and  R.  kanagurta  respectively. Rastrelliger  f i s h e r i e s i n t h e Java Sea have not y e t  ii  reached maximum e x p l o i t a t i o n which suggests the p o s s i b i l i t y of ing p r o d u c t i o n by increasing  fishing  intensity.  increas-  iii  TABLE OF CONTENTS Page ABSTRACT  i  TABLE OF CONTENTS  i i i  LIST OF FIGURES  v  LIST OF TABLES ACKNOWLEDGMENTS I. II. III.  v i i .....  x  INTRODUCTION  1  MATERIALS AND METHODS  2  RESULTS AND DISCUSSIONS  7  1. Systematics Study  7  D e s c r i p t i o n o f t h e genus Rastrelliger Key t o t h e s p e c i e s o f Rastrelliger  ...  7  ....  8  Specific Descriptions  8  Rastrelliger  braahysoma  8  Rastrelliger  kanagurta  9  Nomenclature  12  D i a g n o s t i c Characters  23  2. Morphometric Study  25  Sexual Dimorphism  30  A l l o m e t r i e Growth  30  Geographic V a r i a t i o n s  .  3. M e r i s t i c C h a r a c t e r s 4. Q u a l i t a t i v e Characters  33 45  ...........  49  5.  Population Study Rastrelliger  Fisheries . . .  Population Parameters  . . .  Sexual C o n d i t i o n s  ....  Longevity Environmental  Tolerance  Competitor and Predator  .  Parasites Growth Behaviour Age Length-weight  Relationships  Recruitment S u r v i v a l Rates Mortalities Dynamics o f Populations  ' . . .  Beverton and H o l t Model R i c k e r Model IV. V.  GENERAL DISCUSSIONS CONCLUSIONS  LITERATURE CITED APPENDICES . . .  ,  V  LIST OF FIGURES Figure  Page  1.  Bathymetric Chart o f the Java Sea  3  2.  R a t i o o f Body P a r t s t o Fork Length  16  3.  R a t i o o f Fork Length t o Body Depth  17  4.  Sexual Dimorphisms o f Rastvelligev  5.  Geographical V a r i a t i o n s i n R. bvachysoma  32  6.  Geographical V a r i a t i o n s i n R. kanaguvta  44  7.  F i r s t Occurrence o f Haemal Brace  47  8.  C e p h a l i c L a t e r a l L i n e Canal System o f Rastvelligev  9.  D i g e s t i v e T r a c t s o f Rastvelligev  32  bvachysoma  . .  52 53  10.  Sexual M a t u r i t y Stages Composition o f R. kanagurta  . .  61  11.  Sexual M a t u r i t y Stages Composition o f R. bvachysoma  . .  62  12.  Growth Curve o f R. bvachysoma  69  13.  Growth Curve o f R. kanaguvta  70  14.  R e l a t i o n Between T o t a l E f f o r t and Catch Per U n i t o f E f f o r t o f Rastvelligev  75  kanaguvta  15.  Length Frequency D i s t r i b u t i o n o f R. kanaguvta  16.  Length Frequency D i s t r i b u t i o n o f R. bvachysoma  17.  Catch Curve o f R. kanaguvta  97  18.  Catch Curve o f R. bvachysoma  98  19.  Y i e l d I s o p l e t h Diagrams o f R. kanaguvta  20.  Y i e l d per R e c r u i t as a F u n c t i o n o f F o f R. kanaguvta;  21.  86 ....  87  106  f o r t = t = 4.0 months  107  Y i e l d per R e c r u i t as a F u n c t i o n o f F o f R. kanaguvta;  f o r t = 4.5 and t = 4.0 months  ....  108  vi Figure  Page  22.  Y i e l d I s o p l e t h Diagrams o f  23.  Y i e l d per R e c r u i t as a Function o f F o f R. braahysoma;  R. braahysoma  f o r t = t = 3.0 months . . . p  109 110  24. Y i e l d per R e c r u i t as a Function o f F o f i?. braahysoma;  f o r t = 4.0 and t = 3.0 months  Ill  vii LIST OF TABLES Table 1.  Page Morphometric Measurements o f  Rastvelligev  bvachysoma  11  2.  Morphometric Measurements o f R. kanaguvta  13  3.  Frequency D i s t r i b u t i o n o f the Ratios o f HeadLength to Body Depth  4.  18  Frequency D i s t r i b u t i o n o f the Ratios o f ForkLength to Body Depth  5.  !  9  Frequency D i s t r i b u t i o n o f the Ratios o f I n t e s t i n e Length to Fork Length  20  6.  Regressions o f Sample No. 1  26  7.  Regressions o f Sample No. 2  27  8.  Regressions o f Sample No. 3  28  9.  Regressions o f Sample No. 4  10.  35  Comparisons o f Body P r o p o r t i o n s Between C l a s s Modes o f 14.0 cm FL and 16.0 cm FL  14.  34  Comparisons o f Body P r o p o r t i o n s Between C l a s s Modes o f 14.0 cm FL and 20.0 cm FL  13.  31  Comparisons o f Body P r o p o r t i o n s Between C l a s s Modes o f 16.0 cm FL and 20.0 cm FL  12.  29  Comparisons o f Body P r o p o r t i o n s Between Males and Females  11.  .' . . .  36  Comparisons o f Body P r o p o r t i o n s Between Samples No. 1 and No. 2  37  vi i i Table 15.  Page Comparisons o f Body P r o p o r t i o n s Between Samples No. 3 and No. 4 . .  16.  38  Comparisons o f Body P r o p o r t i o n s Between Samples No. 1 and No. 3  17.  39  Comparisons o f Body P r o p o r t i o n s Between Samples No. 2 and No. 4  18.  Comparisons o f Body P r o p o r t i o n s Between Samples No. 2 and No. 3  19.  40 .  41  Comparisons o f Body P r o p o r t i o n s Between Samples No. 1 and No. 4  42  20.  Covariance Analyses f o r P a i r s o f Rastrelliger  43  21.  G i l l Raker Counts o f Rastrelliger  48  22.  The Degree o f I n t e r g r a d a t i o n s o f the T o t a l G i l l Raker Counts o f Rastrelliger  23.  48  Productions o f Payang F i s h e r i e s i n the North Coast o f Java  54  24.  F i e l d Key o f M a t u r i t y Stages (Males)  58  25.  F i e l d Key o f M a t u r i t y Stages (Females)  59  26.  Von B e r t a l a n f f y Growth Parameters o f  Rastrelliger  from the I n d o - P a c i f i c Region  71  27.  Age-Length-Weight Key o f R. kanagurta  84  28.  Age-Length-Weight Key o f R. braahysoma  85  29.  The Length-Weight Exponential Values o f of the Java Sea  Rastrelliger  90  ix  Table 30.  Page The Length-Weight Exponential  Values o f  Rastrelliger  from the I n d o - P a c i f i c Region  91  31.  S u r v i v a l Rate o f R.  kanagurta  95  32.  S u r v i v a l Rate o f R.  braahysoma  96  33.  M o r t a l i t y C o e f f i c i e n t s o f R.  34.  Ricker Y i e l d Model o f R.  kanagurta  35.  Ricker Y i e l d Model o f R.  braahysoma  .  116  36.  Ricker Y i e l d Model o f R.  braahysoma  ...  117  kanagurta  100 115  X  ACKNOWLEDGEMENTS I wish t o express my deep a p p r e c i a t i o n and thanks t o my s u p e r v i s o r Dr. Norman J . Wilimovsky who encouraged me t o undertake t h i s study, gave a d v i c e and c r i t i c i s m . My thanks a l s o goes t o Messrs. T.D. l i e s and Stephen Borden, Dr. D.J. R a n d a l l , Dr. J.R. Adams, Messrs. D.E. Wilson, R. S t a n l e y , Ni I-shun and R.S.. M i l n e f o r g i v i n g useful s u g g e s t i o n s . I am very g r a t e f u l to Messrs. R.B. Wilson, B . J . Anderson and Miss C M . McAskie from t h e Canadian I n t e r n a t i o n a l  Development  Agency f o r c o n t r i b u t i n g i n v a r i o u s ways t o t h i s study. F i n a l l y , I wish t o extend my thanks t o my s u p e r i o r i n the D i r e c t o r a t e General o f F i s h e r i e s , Mr. Moh Unar the D i r e c t o r o f the Marine F i s h e r i e s Research I n s t i t u t e , and t o my c o l l e a g u e s i n the Regional F i s h e r i e s S e r v i c e s and the I n s t i t u t e f o r Marine Research i n J a k a r t a f o r a s s i s t i n g i n data c o l l e c t i o n s .  i I.  INTRODUCTION  The Kembung -- the genus Rastrelliger  -- c o n s t i t u t e one o f  the most important groups of f i s h e s o f the a r t i s a n a l f i s h e r i e s o f Indonesia.  On the north c o a s t o f Java i n 1971, the c a t c h was 10,000  tons, c o n s t i t u t i n g over 10% of the t o t a l marine f i s h e r i e s p r o d u c t i o n o f the area. In the f i v e - y e a r s development program of the Government of Indonesia (1969/1974), which i n c l u d e d i n v e s t i g a t i o n of f i s h e r i e s , t h i s genus with tuna and o i l - s a r d i n e s had p r i o r i t y over o t h e r commercial species. During the l a t e f i f t i e s an experimental canning p r o j e c t f o r t h i s genus was unsuccessful due to m i s c a l c u l a t i o n of the stock abundance and mistakes i n e s t i m a t i n g the economics of the p r o j e c t . Most i n v e s t i g a t i o n s on Rastrelliger neighbouring s t a t e s of Indonesia.  are c o n f i n e d to the  The most important c o n t r i b u t i o n i n  the Indonesian waters was conducted by de Beaufort (1951) and o n l y few o b s e r v a t i o n s have been recorded s i n c e . In c o n t r a s t to the r a t h e r e x t e n s i v e f i s h e r i e s i n v e s t i g a t i o n s as d e s c r i b e d above, the i d e n t i t i e s of the s p e c i e s w i t h i n the genus are s t i l l i n doubt. There are many synonyms because l o c a l races or i n d i v i duals have been d e s c r i b e d under d i f f e r e n t names. The o b j e c t i v e s of t h i s t h e s i s are: (1) to v e r i f y the s p e c i e s i d e n t i t i e s , (2) to study t h e i r morphometry, and (3) to estimate the p o p u l a t i o n parameters to a i d f i s h e r i e s management.  2  II.  MATERIALS AND METHODS  During the 1972 f i s h i n g season ( e a r l y West Monsoon) samples of Rastrelliger  were c o l l e c t e d from the two main f i s h i n g areas i n the  Java Sea, i . e . , Tanjung S a t a i i n the south west coast o f Borneo and J a k a r t a i n the north coast of Java (Figure 1). A l l the f i s h were c o l l e c t e d from the same f i s h i n g gear, the shore seines having s t r e t c h e d mesh s i z e of about 3.0 to 4.5  cm.  The samples were temporarily preserved i n f o r m a l i n  10%  (+ borax, to r e t a r d shrinkage) and t r a n s f e r r e d to 37% i s o p r o p y l alcohol. Measurements were made using d i a l c a l i p e r and a metric s c a l e . S i x t e e n morphometric, seven m e r i s t i c and some q u a l i t a t i v e c h a r a c t e r s were examined on a l a r g e s e r i e s of specimens. Proportion were c a l c u l a t e d from the numbers of specimens mentioned i n the d e s c r i p t i o n or on the t a b l e s . M e r i s t i c characters were determined from  appearing  radiographs.  C l e a r i n g and s t a i n i n g were done f o r bone s t r u c t u r e examinations. The measurements and counts used i n t h i s study are those defined by Hubbs and L a g l e r (1964) with some options which are described on page F i s h e r i e s data were c o l l e c t e d from Regional  4.  Fisheries  S e r v i c e s , the Marine F i s h e r i e s Research I n s t i t u t e and the I n s t i t u t e f o r Marine Research i n J a k a r t a . Each morphometric character was subjected to r e g r e s s i o n analysis.  Regression  l i n e s were compared by covariance a n a l y s i s . Other  characters were t r e a t e d to b a s i c s t a t i s t i c a l  analyses.  3  Figure  1. Bathymetric  c h a r t o f the Java Sea. Depth i n meters,  shaded p a r t r e p r e s e n t s an area 30 t o 60 m i l e s o f f shore where sampled R a s t r e l l i g e r were taken.  4/  A l l c a l c u l a t i o n s were performed on IBM 1130 and 360/67 Computers, using programs that are a v a i l a b l e at the U.B.C. Computing Centre.  Anatomical Features, Terms jl. FORK LENGTH (FL):  i s the d i s t a n c e from the most a n t e r i o r p a r t  of the head (L) to the end of the membranous edge of caudal f i n at f o r k ( F ) . 2.  BODY LENGTH (BL):  i s the d i s t a n c e from the most a n t e r i o r part  of the head (L) to the i n s e r t i o n of the caudal f i n ' s dorsal lobe (B). 3.  GILL COVER HEAD LENGTH ( L G ) :  i s the d i s t a n c e from the most ante-  1  r i o r point of the snout (head), i . e . , mandibular symphysis L, to the most d i s t a n t point of the o p e r c u l a r membrane ( p o s t e r i o r membranous edge g i l l cover, 4.  G ). 1  MAXILLARY (sheath) LENGTH (UJ):  i s length of the upper jaw, which  is taken from the a n t e r i o r most p o i n t of the p r e m a x i l l a r y  to  the p o s t e r i o r most point of the m a x i l l a r y . 5.  HEAD DEPTH ( Y J ) : 1  i s measured from the m i d l i n e at the o c c i p u t  v e r t i c a l l y downward to the v e n t r a l contour of the head.  For the  sake o f p r a c t i c a l i t y t h i s head depth i s measured from the g i l l cover notch (Y) the head ( J ' ) .  v e r t i c a l l y downward to the v e n t r a l  contor of  6. DORSO VENTRAL DEPTH (D1V): o r a n t e r i o r dorsal depth, i s t h e d i s t a n c e from the i n s e r t i o n o f a n t e r i o r dorsal ( i . e . i n t e r s e c t i o n a n t e r i o r margin f i r s t dorsal spine, f i n held e r e c t , with the contour o f the back) t o the i n s e r t i o n o f a n t e r i o r ventral f i n . 7. DORSO ANAL DEPTH (D2A):  i s the d i s t a n c e from the i n s e r t i o n  f i r s t r a y o f p o s t e r i o r dorsal t o the i n s e r t i o n f i r s t anal f i n ray, i t i s s l i g h t l y o b l i q u e . 8. GREATEST DEPTH ( h ) : i s body depth, i . e . , t h e g r e a t e s t dorsov e n t r a l dimension, e x c l u s i v e o f t h e f l e s h y o r s c a l y s t r u c t u r e s which p e r t a i n t o t h e f i n bases. 9. PERPENDICULAR IRIS DIAMETER ( I h ) : i s measured v e r t i c a l l y . 10.  PERPENDICULAR PUPIL DIAMETER (Eh): i s measured v e r t i c a l l y .  11.  LENGTH OF PECTORAL FIN (Ph): i s the d i s t a n c e from the extreme base o f uppermost o r outermost r a y t o the f a r t h e s t t i p o f the pectoral f i n .  12.  LENGTH OF PELVIC FIN (Vh): i s the d i s t a n c e from t h e extreme base o f the anteriormost  r a y t o the f a r t h e s t t i p o f the p e l v i c  fin. 13.  INTERORBITAL DISTANCE (00): o r i n t e r o r b i t a l width i s the l e a s t bony width that i s measured where the points a r e pressed t i g h t l y a g a i n s t the bone so as t o e l i m i n a t e so f a r as p r a c t i c a b l e the thickness o f the f l e s h o v e r l y i n g the bony rims.  6  14.  PECTORAL BREADTH (PP):  i s t h e d i s t a n c e measured from the o r i g i n  of the l e f t p e c t o r a l f i n t o the r i g h t p e c t o r a l f i n , i t i s a projection. 15.  NUMBER OF GILL RAKERS: unless otherwise s t a t e d t h e count i s t h a t of the f i r s t g i l l a r c h .  The numbers on the upper limb and lower  limb a r e taken s e p a r a t e l y ; t h e two f i g u r e s a r e separated by a plus sign.  A g i l l raker t h a t s t r a d d l e s t h e angle o f the arch i s  i n c l u d e d i n the count o f the lower limb.  A l l the rudimentary  r a k e r s a r e i n c l u d e d i n t h e count. 16.  NUMBER OF RAYS OF THE ANTERIOR DORSAL FIN:, a l l spines a r e designated by roman numerals no matter how rudimentary o r how f l e x i b l e they may be. True spines a r e unpaired (median) s t r u c t u r e s , without segmentation.  S o f t rays a r e designated by A r a b i c numerals, a r e  u s u a l l y ( n o t always) branched and f l e x i b l e , and a r e b i l a t e r a l l y p a i r e d and segmented.  7  III. 1.  RESULTS AND DISCUSSION  Systematics Studies D e s c r i p t i o n o f the Genus Jordan and S t a r k s .  Rastvelligev  Jordan and S t a r k s , 1908:607 ( o r t h o - t y p e :  Rastvelligev bvaahysomus  Soombev  Bleeker, 1851).  D e s c r i p t i o n -- A d u l t s m a l l , from 15 t o 35 cm. Body f u s i f o r m , moderately compressed; body and cheek covered with small s c a l e s , those o f the b r e a s t l a r g e r than o t h e r s .  Eyes with well developed adipose e y e l i d .  Mouth  moderately l a r g e , m a x i l l a r y reaching t o a p o i n t n e a r l y v e r t i c a l below p o s t e r i o r edge o f eye. edentulous.  Small t e e t h i n jaws.  G i l l rakers long and numerous, f e a t h e r l i k e :  mouth i s opened.  Two d o r s a l s , the f i r s t spinous.  Five o r s i x f i n l e t s behind d o r s a l and a n a l . P e c t o r a l s s h o r t , pointed with broad base. rays.  Vomer and p a l a t i n e s  Marine, i n l a r g e s c h o o l s , i n s h o r e .  v i s i b l e when  Anal without s p i n e s .  Caudal deeply f o r k e d . P e l v i c s with spines and f i v e Feeds on both zoo- and  phyto-plankton. Rastvelligev  i s a t present considered t o c o n t a i n two s p e c i e s o c c u r r i n g  in abundance throughout the I n d o - P a c i f i c Region: Ocean and western P a c i f i c Ocean.  i n t r o p i c a l Indian  8  Key t o the Species o f Rastvelligev 1.  Jordan and Starks  Greatest body depth i n f o r k length 3.1 - 3.7 (x = 3.4); very f i n e l y d e n d r i t i c c e p h a l i c l a t e r a l l i n e system; head length s l i g h t l y l e s s e r than g r e a t e s t body depth 0.89 - 1.07 (x = 0.98); l e n g t h o f i n t e s t i n e i n f o r k length 2.2 - 3.0 (x = 2.5); d i g e s t i v e t r a c t very convoluted , R.  2.  bvachysoma.  Greatest body depth i n f o r k l e n g t h 3.8 - 4.4 (x = 4.0); not f i n e l y d e n d r i t i c c e p h a l i c l a t e r a l l i n e system; head length d i s t i n c t l y g r e a t e r than g r e a t e s t body depth 1.01 - 1.19 (x = 1.11); length o f i n t e s t i n e i n f o r k l e n g t h 1.3 - 1.4 (x - 1.35); d i g e s t i v e t r a c t l e s s convoluted  R.  kanaguvta.  Specific Descriptions 1. Rastvelligev Scombev  bvachysomus  Scombev  kanaguvta  bvachysoma  (Bleeker)  Bleeker, 1851:356 ( d e s c r i p t i o n , o c c u r r e n c e ) . B l e e k e r , 1852:34 (nec. Cuvier and Valenciennes,  description). Scombev  neglectus  van Kampen, 1907:7 ( d e s c r i p t i o n ) .  Rastvelligev  bvachysoma  Rastvelligev  neglectus  Fowler, 1928:132 (morphometric d e s c r i p t i o n ) . de B e a u f o r t , 1951:211 ( d e s c r i p t i o n , f i g u r e ,  occurrence). D e s c r i p t i o n -- Body compressed, g r e a t e s t body depth 3.4 (3.1 - 3.7) i n FL a t o r i g i n o f the seventh d o r s a l s p i n e .  Head l e n g t h l e s s e r than  or a s l i g h t l y g r e a t e r than g r e a t e s t depth 0.98 (0.89 - 1.07);  9 3.5 (3.3 - 3.7) i n FL. Eye about equal to i n t e r o r b i t a l space.  Mouth  o b l i q u e , m a x i l l a r y reaching to below hind border o f eye. A s i n g l e s e r i e s o f f i n e and p o i n t e d teeth i n the jaws.  P a l a t e edentulous.  G i l l rakers  19 (17-21) on the upper limb o f the f i r s t g i l l a r c h ; the l o n g e s t ones equal o r g r e a t e r than the d i s t a n c e between snout and p u p i l . F i r s t d o r s a l spine s h o r t e r than second.  Second d o r s a l f i n concave.  Anal f i n s i m i l a r  to second d o r s a l ; o r i g i n o f anal s l i g h t l y behind t h a t o f second d o r s a l . P e c t o r a l t r i a n g u l a r , longer than v e n t r a l ; about equal o r g r e a t e r than post o r b i t a l p a r t o f head. S c a l e s c t e n o i d . L a t e r a l l i n e s c a l e s 125 (120-131); s l i g h t l y curved. Fin formulae:  Measurements o f 117 specimens on Table 1.  XI(X - X I ) ;  D 12(12 - 13) + 5(5 - 6 ) ; A 13 + 5(5 - 6 ) ; 2  P 18(16 - 1 8 ) ; P 1.5; vertebrae 31(38 specimens). 1  2  Colour i n l i f e :  B l u i s h - g r e e n i n the back above l a t e r a l l i n e s and s i l v e r y  in the b e l l y and s i d e s below l a t e r a l l i n e s .  A row o f dark spots along  base o f f i r s t dorsal with dusky i n c o l o u r . P e c t o r a l , v e n t r a l and anal f i n s y e l l o w i s h - h y a l i n e with dusky margins.  Caudal f i n y e l l o w i s h .  C o l o u r a t i o n s o f preserved specimens g r a d u a l l y fades t o b l u i s h grey and d u l l white.  Local common name:  Kembung Perempuan.  L o c a l h a b i t a t : Coastal waters o f Indonesian A r c h i p e l a g o . Range: The range extends from Andaman I s . through Indonesian Arch. to F i j i and Solomon I s . 2. Scomber  Rastrelliger  kanagurta  Rarely found i n South A f r i c a n waters. kanagurta  (Cuvier)  C u v i e r , 1817:313 ( d e s c r i p t i o n ) .  10 \Scombev loo  Lesson, 1829:277 (occurrence).  Scomber chrysozonus  Ruppell , 1835:10 (occurrence, f i g u r e ) . R u p p e l l , I bid:37 ( d e s c r i p t i o n , f i g u r e ) .  Scomber microlepidotus Scomber moluccensis Scomber reani  Day, 1870:690 (occurrence).  Scomber lepturus Eastrelliger  Bleeker, 1856:40 ( d e s c r i p t i o n ) .  A g a s s i z , 1874:tab.2 (occurrence).  brachysomus  Jordan and Dickerson, 1908:610 (nec. Bleeker,  d e s c r i p t i o n , occurrence, f i g u r e ) . Jordan and S t a r k s , 1917:440 (occurrence).  Rastrelliger  kanagurta  Rastrelliger  ehrysozonus  Kishinouye, 1923:406 ( c l a s s i f i c a t i o n , synonymy,  description, distribution, figure). Rastrelliger  microlepidotus  Rastrelliger  serventyi  Barnard, 1927:296 (occurrence).  Whitley, 1944:268 (occurrence, d e s c r i p t i o n ) .  D e s c r i p t i o n -- Body moderately compressed; g r e a t e s t depth 4.0 (3.8-4.4) i n FL a t t h e o r i g i n o f the seventh d o r s a l spine.  Head l e n g t h d i s t i n c t l y  g r e a t e r than g r e a t e s t depth, 3.6 (3.5 - 3.7) i n FL. Eye equal o r s l i g h t l y l e s s than i n t e r o r b i t a l space.  Mouth o b l i q u e , m a x i l l a r y not  reaching to a point below hind border o f eye o r not so f a r i n young specimen. A s i n g l e s e r i e s o f f i n e pointed t e e t h i n t h e jaws. P a l a t e and vomer edentulous.  G i l l r a k e r s 21 (18 - 23) on t h e upper limb and  37 (35 - 39) on t h e lower limb o f t h e f i r s t l e f t g i l l a c r h ;  the longest  11 TABLE 1 Morphometric Measurements o f braahysoma  No.  Character  Rastrelliger  B l e e k e r (n = 117)  Mean  Standard Error  Range  1  Fork Length  15.50  T.39  12.20 - 18.20  2  Total Length  17.40  1.63  13.70 - 20.50  3  Body Length  14.09  1.29  11.10 - 16.50  4  Head Length  4.45  0.43  3.50 -  5.30  5  M a x i l l a r y Length  2.46  0.29  1.80 -  3.10  6  Head Depth  3.54  0.37  2.70 -  4.40  7  .Dorsoventral Depth  4.40  0.48  3.30 -  5.60  8  Dorsoanal Depth  4.17  0.42  3.20 -  5.10  9  G r e a t e s t Depth  4.53  0.50  3.40 -  5.80  10  Perp. I r i s Diam.  0.91  0.09  0.70 -  1.20  11  Perp. Pupil Diam.  0.49  0.05  0.30 -  0.70  12  P e c t o r a l F i n Length  2.19  0.25  1.60 -  2.70  13  P e l v i c F i n Length  1.90  0.23  1.40 -  2.90  14  I n t e r o r b i t a l Distance  0.94  0.12  0.60 -  1.30  15  P e c t o r a l Breadth  2.10  0.28  1.40 -  2.70  12 equal to d i s t a n c e from p u p i l to snout.  F i r s t d o r s a l spine s h o r t e r  than second and equal to d i s t a n c e from snout to eye; l a s t spine very small.  A n t e r i o r rays o f second d o r s a l f i n l o n g e s t , s l i g h t l y l e s s than  f o u r t h spine o f f i r s t d o r s a l . The edge o f second d o r s a l and anal f i n s concave.  O r i g i n o f anal f i n s l i g h t l y behind t h a t o f second d o r s a l ;  s i m i l a r i n shape.  P e c t o r a l pointed and t r i a n g u l a r . S c a l e s c t e n o i d ,  l a t e r a l l i n e 130 (125 - 140). Measurements o f 103 specimens on Table 2. F i n formulae:  D XI(IX - X I ) ; ]  D 12(12 - 13) + 5(5 - 6 ) ;  A 13 + 5(5 - 6 ) ; P 19(19 - 20); ]  Colour i n l i f e :  2  P 1.5; 2  v e r t e b r a e 31 (40 specimens).  B l u i s h with greenish-grey str-ipes above and s i l v e r y  below l a t e r a l l i n e s .  Dark spots along the f i r s t d o r s a l base.  Pectoral,  v e n t r a l and anal f i n s h y a l i n e . Dorsals and caudal dusky along margins. Colour o f preserved specimens back b l u i s h grey, d u l l s i l v e r y white. Local common names: Kembung L e l a k i , Kembung, Banyar. Local h a b i t a t : A l l over Indonesian waters. Range:  The range extends from Durban (South A f r i c a ) , P e r s i a n G u l f ,  through C e n t r a l I n d o - P a c i f i c a r e a , Ryukyu, Queensland  (Australia),  F i j i to Hawaii I s . Nomenclature The most important study on Rastrelliger made by de B e a u f o r t (1951).  i n t h i s r e g i o n was  No other work has been done s i n c e .  In s p i t e o f the e x t e n s i v e i n v e s t i g a t i o n s being done i n T h a i l a n d and I n d i a , the nomenclature o f the f i s h i s s t i l l i n doubt.  13 TABLE 2 Morphometric Measurements o f Rastrelliger kanagurta C u v i e r (n = 103) No.  Character  Mean  Standard Error  Range  1  Fork Length  17.41  2.08  13.90 - 21.90  2  T o t a l Length  19.39  2.35  15.40 - 24.40  3  Body Length  15.98  1.90  12.60 - 20.00  4  Head Length  4.84  0.57  3.90 -  6.20  5  M a x i l l a r y Length  2.48  0.35  1.80 -  3.30  6  Head Depth  3.39  0.43  2.60 -  4.40  7  Dorsoventral Depth  4.27  0.54  3.10 -  5.50  8  Dorsoanal Depth  4.06  0.52  3.10 -  5.20  9  G r e a t e s t Depth  4.35  0.58  3.30 -  5.60  10  Perp. I r i s Diam.  1.03  0.14  0.80 -  1.50  11  Perp. Pupil Diam.  0.57  0.07  0.40 -  0.80  12  Pectoral F i n Length  2.29  0.33  1,70 -  3.10  13  P e l v i c F i n Length  1.93  0.27  1.20 -  2.60  14  I n t e r o r b i t a l Distance  1.02  0.16  0.70 -  1.40  15  Pectoral Breadth  2.32  0.38  1.60 -  3.20  14  Its synonymy i s r a t h e r obscure because l o c a l races o r i n d i v i d u a l s have been d e s c r i b e d under d i f f e r e n t names. The taxonomic p o s i t i o n o f t h e genus  has been  Rastrelliger  accepted s i n c e Jordan and Starks  (1908)  proposed i t f o r the mackerels  having long g i l l r a k e r s . Starks  (1921)  r a i s e d t h e subgenus  as a genus beside the genera  Scomber  and Rastrelliger.  Pneumatophorus  Fraser-Brunner  and C o l l e t t e and Gibbs ( 1963) recognized only two genera, i . e . ,  (1950) Scomber  ( i n c l u d i n g Pneumatophorus) and  Rastrelliger.  There a r e s e v e r a l i n t e r p r e t a t i o n s a t the s p e c i e s l e v e l . De B e a u f o r t (in de Beaufort and Chapman, 1951) l i s t s three s p e c i e s , Rastrelliger  Cuvier. Manacop zonus  He noted t h a t (1956)  R. braahysoma  may be a v a r i a n t o f R.  He f u r t h e r s t a t e d t h a t braahysoma  B l e e k e r , and  Ruppell.  R. ohrysozonus  s p e c i e s and c o n s i d e r e d opposed de B e a u f o r t  R. braahysoma  R. negleotus  R. kanagurta  Jones and S i l a s  R. negleotus  (1951)  van Kampen and  R. negleotus  d e s c r i b e d o n l y two s p e c i e s  Ruppell.  synonym o f R. of  Bleeker,  braahysoma  ( 1962)  and  R.  kanagurta  negleotus. R. chryso-  van Kampen i s a C u v i e r i s a synonym recognized two  a s a synonym o f R.  braahysoma  and  d e s c r i p t i o n . T h e i r incomplete evidence caused  some c o n f u s i o n among the workers i n Indonesia and a d j a c e n t r e g i o n s who s t i l l recognized and used de Beaufort's works.  Druzhinin  (1968)  supports  de B e a u f o r t and s t a t e s t h a t he i s n o t i n agreement w i t h Jones and S i l a s , however, with no s t r o n g arguments. Matsui  (1967)  f o r m e r l y was named R. braahysoma  questioned.  and  proposed a new s p e c i e s ,  Scomber australasicus;  R. kanagurta.  R. faughni  sp.n., which  and recognized two o t h e r s p e c i e s ,  H i s proposal i s s t i l l w i d e l y  15 The c o n t r o v e r s y , thus, r e s t s on whether R. braahysoma R. negleotus  and  are different species. The frequency d i s t r i b u t i o n o f the r a t i o s o f head l e n g t h t o  g r e a t e s t body depth f o r Rastrelliger  from the north c o a s t o f Java and  Tg. S a t a i ( F i g u r e 3, Table 3) i s d i s t i n c t l y bimodal with a s l i g h t overlap.  The degree o f i n t e r g r a d a t i o n o f the two sympatric samples a r e  5.6% from J a k a r t a and 2.2% from Tg. S a t a i a r e a . The frequency d i s t r i b u t i o n o f the r a t i o s o f g r e a t e s t body depth t o f o r k l e n g t h i s a l s o bimodal and show no o v e r l a p with 0.0% degree o f i n t e r g r a d a t i o n between these sympatric samples ( F i g u r e 2, T a b l e 4 ) . The r a t i o s o f the l e n g t h o f i n t e s t i n e t o f o r k length show non-overlapping ranges, o f which the degree o f i n t e r g r a d a t i o n i s 0.0% (Table 5). Those c h a r a c t e r s t h a t belong to two groups t h a t e x i s t s y m p a t r i c a l l y , with no i n t e r g r a d a t i o n between each o t h e r , and, t h e r e f o r e , the two groups should be c o n s i d e r e d as two v a l i d s p e c i e s . The f i r s t group i n c l u d i n g samples no. 1 and no. 2 i s Rastrelliger and the second group R. kanagurta,  braahysoma  c o n t a i n s samples no. 3 and no. 4.  De B e a u f o r t (1951) s t a t e d t h a t he r e c o g n i z e d R.  negleotus  van Kampen (1907) with t h e f o l l o w i n g arguments "Van Kampen (I.e.) pointed o u t , t h a t the two common s p e c i e s o f Rastrelliger Sea have been confused by Bleeker and o t h e r s .  i n the Java  The s p e c i e s t h a t B l e e k e r  c a l l e d loo C u v i e r and Valenciennes, i s t h e same as t h a t o f French a u t h o r s , but i t i s a synonym o f kanagurta.  The o t h e r s p e c i e s i s mentioned by  B l e e k e r and o t h e r s as kanagurta,  and had t h e r e f o r e to be renamed. Van  Kampen c a l l e d i t negleotus"  .  With regard to braahysoma  de Beaufort  16  Figure  £, G r a p h i c c o m p a r i s o n of observed ranges and m e a n s . Ratio of fork length F L to greatest body depth (h) of R a s t r e l l i g e r of four samples f r o m two different l o c a l i t i e s . B a s e line r e p r e s e n t s range, white bar twice standard deviation, short v e r t i c a l bar m e a n .  17 No.  1  1  If-  I  1  I  l  5r-  LG/h  "-70 N-45  .  »  1  •  N«o4  H  1  -1  1  I  TL/h  N«72  N-45  i  '  3f  I  i  N-34 N-63  "I  6  I  'i  I  I  iL.  1  2f  i ^ °  Q  ,  1  I  I  f ^ —  8  Figure  •  I  '.  2  n  ,  £ BL/h  -4P  1  I  |'  .6 •  K-72  3J.  2  ,  ,4  1  V  ,  N-35  i  '  '  I  '1  r - ^  H-67 ,  4 0 f  ,  .,2  3. Ratio of head length (LG), total length (TL), and body length (BL)  each to greatest body depth (= height, h) of four samples  of Rastrelliger  from two l o c a l i t i e s .  Base line represents  range, white bar twice standard deviation, short vertical bar mean.  TABLE 3 Frequency D i s t r i b u t i o n o f the Ratios o f Head Length t o Greatest Body Depth o f Head Lenqth Body Depth SAMPLE  0.89  0.92  0.95  0.98  No. 1 x = 0.996 S.D. = 0.055  2  1  12  19  2.8  1.4  16.7  26.4  1  8  7  17.8  15.6  No. 2 x = 0.970 S.D. = 0.038  2.2  20 44.4  1.01  . 23  Intergradation: SYMPATRIC: No. 1 - No. 3 : 5.6% No. 2 -- No. 4 : 2.2%  1.07  9  6  31.9  12.5  7  2  15.6  No. 3 x = 1.110 S.D. = 0.038 No. 4 x = 1.117 S.D. = 0.034  1.04  1.10  Rastrelliger  1.16  1.13  1.19  72  8.3  100 45  -  4.4 1  N  100 9  10  8  4 11.8  2.9  26.5  29.4  23.5  2  1  16  17  14  2.9  1.5  23.5  25.0  20.6  OTHERS:  No. No. No. No.  1 - No. 2 1 No. 4 2 No. 3 3 No. 4 —  —  —  : : : :  7  2 5.9 11  10.3 16.2  32.8% 6.35% 1,45% 43.4%  34 100 68 100  '  TABLE 4 Frequency Distribution of the Ratios of Fork Length to Greatest Body Depth in Fork Lenath Body Depth  3.1  3.2 :  3.3  3.4  3.5  3.6  3.7  1  2  14  20  16  13  7  1.4  2.7  19.2  27.4  21.9  17.8  9.6  1  3  12  13  12  4  1  2.2  6.5  26.1  28.2  26.1  8.7  2.2  3.8  4.0  3.9  4.1  4.2  Rastrelliger N  4.4  •4.3  SAMPLE No. 1 x = 3.46 S.D. = .14 cv = 4.05 No.  2  x = 3.40 S.D. = .13 cv = 3.68 No.  3  x = 3.98 S.D. = .13 cv = 3.20 No.  4  x = 4.03 S.D. = .15 cv = 3.63  73 100 46 100 6  9  7  7  4  17.2  25.7  20.0  20.0  11.4  9  10  17  19  9  35 100 2  68  2 -  13.3  14.7  25.0  27.9  13.3  2.9  2.9  100 _J  Intergradation: SYMPATRIC: No. 1 ~ No. 3 : No. 2 No. 4 : —  0.0% 0.0%  OTHERS:  No. 1 — No. 2 No. 1 — No. 4  : :  41.75% 0.0%  No. 2 — No. 3 No, 3 — No. 4  : 0.0% : 42.2%  SAMPLE  No. 1  TABLE 5 Ratios of the Length of Intestine to Fork Length of  Rastrelliger  ForkLength 17.671 17.887 18.238  x= No. 2  x=  Intestine Fork Length  SAMPLE  ForkLength  Intestine Fork Length  2.48 2.51  No. 3  20.434 18.028  1.38 1.35  19.988  1.37 1.35  18.524 18.170  2.56 2.60 2.55  19.694 17.609  1.33  18.098  2.54  19.151  1.36  17.535 16.351  2.95 2.22  18.147  1.32  19.507  1.38  16.207 17.479  2.42  18.693 18.802  1.36 1.33  18.747  2.80  15.437 16.959  2.31 2.55  18.787  1,35  No. 4  2.61  Intergradation between SYMPATRIC groups:  No. 1 - No. 3  :  0.0%  No. 2 - No. 4  :  0.0%  o  21 (1951) commented: " I t was not 5, as s t a t e d by Bleeker, but 6 f i n l e t s behind dorsal and a n a l , and d i f f e r s from the other I n d o - A u s t r a l i a n s p e c i e s o f Rastvelligev  by i t s great depth " (page 212).  In my o p i n i o n , Van Kampen's (1907) d e c i s i o n to name t h e species with great body depth as neglectus  cannot be accepted,  because Bleeker i n 1851 already named i t bvachysoma.  His view  probably was caused by Bleeker's i n adequate d e s c r i p t i o n s s i n c e i t was d e s c r i b e d from a s i n g l e specimen ( 120 mm long and without a caudal fin). Comparison o f Bleeker's (1851), Van Kampen's (1907) and de Beaufort's (1951) data with t h a t o f t h e present study a r e as f o l l o w s (Figure 3 ) : R. bvachysoma  Bleeker (1851), de Beaufort  (1951).  - Height 2.79. T h i s i s w i t h i n the range o f g r e a t e s t body depth i n BL o f sample no. 1 and no. 2: 2.79 - 3.34 ( x = 3.14; x = 1  2  3.10). -  Head as long as high.  T h i s i s w i t h i n t h e range o f the head  length -- g r e a t e s t body depth r a t i o s o f sample no. 1: 0.89 1.07 (x = 0.996) and sample no. 2: 0.89 - 1.04 (x = 0.970). - Head 3.15 i n length.  T h i s i s w i t h i n the range o f the r a t i o s o f  sample no. 1: 2.99 - 3.46 (x = 3.15) and sample no. 2: 3.08 3.34 (x = 3.20). - G i l l rakers on lower branch 35. T h i s i s w i t h i n sample  no. 1: 3 5 - 3 7 (mode = 36) and sample  37 (mode = 35).  the range o f no. 2: 34 -  R. negleotus  van Kampen (1907), de Beaufort  (1951).  - Height 3.1 - 3.4 i s w i t h i n the range o f g r e a t e s t body depth i n BL. of samples no. 1 and no. 2. - Head as long as high, i s w i t h i n the range o f the head l e n g t h and g r e a t e s t body depth r a t i o s o f samples no. 1 and no. 2. - Head 3.2 - 3.5 i s w i t h i n the range o f head length i n BL o f samples no. 1 and no. 2. - Head 3.8 - 3.9 i n length with caudal.  T h i s i s w i t h i n the  range of head length i n TL o f samples no. 1 and no. 2, i . e . , 3.74 - 4.08 (x = 3.90) and 3.73 - 4.08 (x = 3.93) r e s p e c t i v e l y . - G i l l r a k e r s on lower branch 29 - 34 a r e w i t h i n t h e range o f sample no. 2. These d e s c r i p t i o n s suggest t h a t R. negleotus synonym o f R. braahysoma R. kanagurta  van Kampen i s a  Bleeker.  Cuvier (1817), de Beaufort  (1951).  - Height 3.4 - 3.8. T h i s i s w i t h i n the range o f the g r e a t e s t body depth i n BL o f samples no. 3: 3.49 - 3.95 (x = 3.65) and no. 4: 3.46 - 4.17 (x = 3.70). - Height 4.1 - 4.7 i n length with caudal.  This i s within the  range of the g r e a t e s t body depth i n TL o f sample no. 3: 4.20 4.79 (x = 4.43) and sample no. 4: 4.15 - 4.84 ( x = 4.49). - Head (somewhat) longer than high, i s w i t h i n the range o f the . r a t i o s o f head length to g r e a t e s t body depth o f sample no. 3: 1.04 - 1.19 (x = 1.11) and sample no. 4: 1.01 - 1.19 (x = 1.12).  23 -  Head 3.2 - 3.3 i n l e n g t h .  T h i s i s w i t h i n the range o f head  length i n BL o f sample no. 3: 3.16 - 3.36 (x = 3.29)  and  sample no. 4: 3.14 - 3.50 (x = 3.31). -  Head 3.9 - 4.3 i n length with caudal.  This i s w i t h i n the  range o f head length i n TL of sample no. 3: 3.87 - 4.09 (x = 3.99) and sample no. 4: 3.86 - 4.37 (x = 4.01). -  G i l l rakers on lower branch 35 - 38, are w i t h i n the range o f sample no. 3: 35 - 39 (mode - 37) and sample no. 4: 35 - 37 (mostly: 37). The above comparisons suggest t h a t a l l the d e s c r i p t i o n s o f  Cuvier (1817) and de Beaufort ( 1951) are i n agreement with the data of samples no. 3 and no. 4, i . e . , R.  Diagnostic  kanaguvta.  Characters  Ratio of Fork Length to Greatest Body Depth The r a t i o of values o f f o r k length to g r e a t e s t body depth ranges from 3.10 to 4.40 (Table 4). The frequency d i s t r i b u t i o n of sympatric samples show two d i s t i n c t bimodal histograms with no o v e r l a p . The values o f the degree of i n t e r g r a d a t i o n among samples are: Sample no. no. no. no. no. no.  1 1 1 2 2 3  to to to to to to  no. no. no. no. no. no.  2: 3: 4: 3: 4: 4:  41.75% 0.0 % ( sympatric, Jakarta) 0.0 % 0.0 % 0.0 % (sympatric, Tg. S a t a i ) 42.2 %  The above data suggest t h a t these c h a r a c t e r s are u s e f u l  24  i n d i s t i n g u i s h i n g the two s p e c i e s . Ratio o f Head Length to G r e a t e s t Body Depth The average r a t i o s o f head length to g r e a t e s t body depth ranges from 0.89 to 1.22 (Table 3). The frequency d i s t r i b u t i o n s o f these r a t i o s f o r sympatric samples (no . 1 and no. 3; no. 2 and no. 4) shows two d i s t i n c t bimodal histograms with modes o f 0.98, 1.01, and two modes o f 1.10. Samples from Tg. S a t a i area have an i n t e r g r a d a t i o n value 5.6% and from J a k a r t a area 2.2%.  The degree o f i n t e r g r a d a t i o n between  areas a r e : Sample no. no. no. no.  1 1 3 3  to to to to  no. no. no. no.  2: 4: 2: 4:  32.8% 6.35% 1.45% 43.4%  These c h a r a c t e r s are key c h a r a c t e r s t h a t have been used to distinguish species.  The present data show s l i g h t o v e r l a p s , t h e r e f o r e ,  these c h a r a c t e r s have disadvantages as key-characters. Ratio o f Other Measurements to E i t h e r Head Length or Greatest Body Depth The r a t i o o f body length BL, f o r k length FL, and t o t a l length TL to head l e n g t h , shows a c o n s i d e r a b l e o v e r l o p with degree o f i n t e r g r a d a t i o n ranging from 13.5 - 34.0% between sympatric samples;  while  the r a t i o to g r e a t e s t body depth the degree o f i n t e r g r a d a t i o n ranges from 0.0 - 2.1%, thus, g e n e r a l l y , the r a t i o s o f body p a r t to g r e a t e s t body depth are u s e f u l i n d i s t i n g u i s h i n g s p e c i e s .  25 Ratio o f the Length o f I n t e s t i n e to Fork Length The l e n g t h o f i n t e s t i n e i n FL (Table 5) between  sympatric  samples shows no o v e r l a p , the degree o f i n t e r g r a d a t i o n i s 0.0%. The f i r s t group, i . e . , samples no. 1 and no. 2, has r a t i o s 2.2 - 2.95 (x = 2.54); whereas the second group, samples no. 3 and no. 4, has r a t i o s 1.32 - 1.38 (x = 1.35). This r a t i o i s good as key-character f o r d i s t i n g u i s h i n g s p e c i e s .  2.  Morphometric Study For c h a r a c t e r s s t u d i e d , the r e g r e s s i o n o f each c h a r a c t e r on  f o r k length FL i s a r e c t i l i n e a r r e g r e s s i o n , with c o r r e l a t i o n c o e f f i c i e n t range from 0.71 - 0.99 (Tables y where:  6, 7, 8, & 9 ) .  = a + bx  x  the independent v a r i a b l e , f o r k length  y  t h e dependent v a r i a b l e , l e n g t h o f any body p a r t  The c h a r a c t e r s were examined f o r p o s s i b l e bias caused by sexual dimorphism o r strong a l l o m e t r i c growth. Analysis of covariance indicated that: 1.  l o n g i t u d i n a l measurements and p e l v i c f i n length are s i g n i f i c a n t l y d i f f e r e n t (1%) between sexes (Table 10) ,  2.  p e r p e n d i c u l a r i r i s and p u p i l diameters, p e c t o r a l f i n l e n g t h , and p e c t o r a l breadth show strong a l l o m e t r i c growth ( 1 % l e v e l o f s i g n i f i c a n c e ) (Tables 11,  12,  13).  26 TABLE  6  Regressions o f Sample No. 1 from J a k a r t a , N = 72 y = a + bx, where: x i s fork length, y i s measurements o f any body p a r t s , r i s correlation coefficient, c v . i s coefficient of variation, T i s Student's t value. Character T o t a l length Body length Head length Maxillary l n . Head depth Dorsovent. d. Dorsoana. d. Greatest b.d. I r i s diam. Pupil diam. Pectoral l n . P e l v i c length I n t e r o r b i t . d. Pect. breadth  a  b  -0.2360 0.0292 0.0187 -0.5541 -0.2071 -1.0954 -0.7110 -1.0948 0.0716 0.0766 -0.3756 -0.3765 -0.3006 -1.0682  1.1420 0.9076 0.2880 0.1959 0.2427 0.3531 0.3138 0.3606 0.0550 0.0270 0.1676 0.1483 0.0805 0.2019  S.E. o f b 0.0292 0.0234 0.0123 0.0099 0.0121 0.0188 0.0185 0.0207 0.0065 0.0032 0.0092 0.0165 0.0053 0.0152  r  c. v.  T  %  0.9778 0.9774 0.9416 0.9203 0.9225 0.9132 0.8960 0.9008 0.7078 0.7105 0.9078 0.7303 0.8742 0.8452  1.37 1.36 2.25 3.27 2.79 3.51 3.65 3.77 5.82 5.30 3.40 7.04 4.59 6.00  39.05 38.71 23.40 19.68 19.98 18.74 16.88 17.35 8.38 8.44 18.10 8.94 15.06 13.23  27 TABLE 7 Regressions o f Sample No. 2 from Tg. S a t a i , N = 45 y = a + bx,  Character T o t a l length Body length Head length Maxillary In. Head depth Dorsovent.d. Dorsoanal.d. G r e a t e s t b.d. I r i s diam. Pupil diam. P e c t o r a l In. P e l v i c length Interorbit.d. Pect. breadth  a -0.3889 -01.711 -0.1638 -0.6566 -0.5317 -0.6542 -0.1514 -0.7970 -0.0264 -0.1340 -0.3636 -0.2306 -0.2462 -0.7629  where:  x y r c.v. T  b 1.1413 0.9199 0.2954 0.1996 0.2621 0.3283 0.2807 0.3476 0.0595 0.0413 0.1626 0.1350 0.0763 0.1881  i s fork length, i s measurements o f any body p a r t s , i s correlation coefficient, i s coefficient of variation, i s Student's t value.  S.E.of b 0.0131 0.0060 0.0071 0.0067 0.0079 0.0102 0.0106 0.0105 0.0029 0.0025 0.0053 0.0074 0.0050 0.0081  r  c.v. %  0.9972 0.9991 0.9875 0.9766 0.9807 0.9807 0.9704 0.9810 0.9517 0.9266 0.9777 0.9409 0.9163 0.9619  0.93 0.52 1.99 3.39 2.78 2.84 3.11 2.81 4.00 6.23 3.04 4.89 6.70 4.68  T 86.88 152.83 41.09 29.77 32.88 32.04 26.36 33.12 20.32 16.15 30.52 18.21 15.00 23.08  28  TABLE 8 Regressions of Sample No. 3 from Jakarta, N = 35 y = a + bx ,  where : x y r cv. T  Character  a  Total length Body length Head length Maxillary In. Head depth  -0.3424 -0.2741 -0.0060 -0.4448 0.0842  b  1.1353 0.9318  is is is is is  fork length, measurement of any body part, correlation c o e f f i c i e n t , coefficient of variation, Student's value.  S.E.of b  r  0.0302  0.9885 0.9955  0.1700  0.0153 0.0090 0.0085 0.0101 0.0126  0.2800  cv.  T  %  1.23 0.76 1.47  37.51  0.9610 0.9567 0.9507  2.65  19.97  2.35 2.35  18.86  2.36  18.14  2.94  15.07  0.9831  60.59 30.82  Dorsovent. d  0.3913  0.1920 0.2229  Dorsoanal  d.  0.2400  0.2219  0.0122  Greatest b.d.  0.1010  0.2460  0.0163  0.9533 0.9344  I r i s diam.  -0.1854  0.8713 0.8832  5.19 4.90  Pectoral l n .  -0.1016 -0.3866  0.0069 0.0035  10.20  Pupil diam.  0.0709 0.0386 0.1555  -0.2247  0.1250  0.9374 0.9382  3.39  Pelvic length  0.0100 0.0080  3.23  15.46 15.57  Interorbit.d.  -0.0523 -0.9698  0.0606  0.0066  0.8485  5.16  9.21  0.1916  0.0093  0.9631  3.05  20.54  Pect. breadth  17.60  10.81  29  TABLE 9 Regressions o f Sample No. 4 from Tg S a t a i , N = 68 y = a + bx ,  Character  T o t a l length Body length Head length Maxillary In. Head depth Dorsovent. d. Dorsoanal. d. Greatest b.d. I r i s diam. Pupil diam. Pectoral In. P e l v i c length I n t e r o r b i t . d. Pect. breadth  a  -0.0062 0.1484 0.1895 -0.2823 -0.1805 -0.3092 -0.2785 -0.4484 -0.0524 0.0695 -0.3793 -0.2536 -0.2862 -0.5646  where:  x y r c.v. T  b  1.1119 0.9090 0.2660 0.1578 0.2041 0.2599 0.2487 0.2754 0.0620 0.0285 0.1526 0.1253 0.0752 0.1642  i s fork l e n g t h , i s measurement o f any body p a r t , i s correlation coefficient, i s coefficient of variation, i s Student's t v a l u e .  S.E.of b 0.0124 0.0068 0.0051 0.0041 0.0044 0.0065 0.0057 0.0071 0.0030 0.0018 0.0044 0.0039 0.0033 0.0063  r  c.v.  T  %  0.9959 0.9981 0.9881 0.9778 0.9845 0.9798 0.9831 0.9786 0.9302 0.8801 0.9728 0.9691 0.9417 0.9538  1.21 0.80 1.99 3.19 2.50 2.92 2.65 3.09 5.52 6.27 3.71 3.84 6.12 5.25  89.37 133.03 52.09 37.87 45.60 39.78 43.56 38.61 20.59 15.06 34.10 31.91 22.74 25.79  30 Sexual Dimorphism Rastrelliger  braahysoma  show sexual dimorphism i n body  l e n g t h , m a x i l l a r y l e n g t h , v e n t r a l f i n l e n g t h , and probably caudal f i n length (Table 10). The male has a s h o r t e r head, s h o r t e r m a x i l l a r y , s h o r t e r v e n t r a l f i n and s h o r t e r body; and probably has a longer caudal f i n . The purpose of t h i s sexual dimorphisms i s not y e t been studied i n t h i s p a r t i c u l a r f i s h . I speculate that t h i s dimorphisms i s more f o r sexual purposes r a t h e r than f o r d i s p l a y ; such as longer v e n t r a l f i n i n female i s probably f o r o b t a i n i n g b e t t e r balance and d i v e r g i n g the eggs while d i s c h a r g i n g them. T h i s dimorphism i s l e s s l i k e l y to appear i n f i n s which are c r i t i c a l f o r locomotion.  The longer body  i n female can be r e l a t e d to the need f o r more space i n body c a v i t y f o r eggs, as female gonads are g e n e r a l l y much bigger than male gonads. The longer head and m a x i l l a r y are probably r e l a t e d to the more i n t e n s i v e and a c t i v e feeding i n the female than i n the male. The above c h a r a c t e r s should not be used f o r r a c i a l s t u d i e s . A l l o m e t r i c Growth The morphometric data of R. kanagurta  suggest t h a t perpendic-  u l a r i r i s and p u p i l diameters, p e c t o r a l f i n l e n g t h , and p e c t o r a l breadth show strong a l l o m e t r i c growth (Table 11, 12, 13). These c h a r a c t e r s cannot be used f o r r a c i a l s t u d i e s  purposes.  31 TABLE 10 Comparison o f Body Proportions o f Rastrelliger spp. by Covariance A n a l y s i s f o r the Males and Females Taken from Tg. S a t a i . Data Show Variance Ratio and i t s S i g n i f i c a n c e . Fr  i s the v a r i a n c e r a t i o t o t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n d i f f e r e n c e , Fb t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e , Fa t o t e s t the a d j u s t e d mean d i f f e r e n c e . In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the adjusted mean becomes inappropriate. Character Total l e n g t h Body length Head length M a x i l l a r y length Head depth Dorsoventral depth Dorsoanal depth Greatest body depth Perp. i r i s diameter Perp. p u p i l diameter P e c t o r a l f i n length P e l v i c f i n length Interorbital distance P e c t o r a l breadth  Fr 3.91** 6.46*** 1.35 1.36 2.11 1.03 1.94 1.00 1.16 1.80 2.02 14.88*** 1.24 1.05  Fb  Fa  0.14 0.07 7.38** 5.32* 1.89 0.89 1.52 1.90 2.62 0.87 0.17 0.001 1.10 1.04  5.58* 1.97 (0.05) 0.51 0.49 0.36 0.00007 0.33 0.02 2.59 2.18 1.63 0.91 0.000003  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l . Note:  The above species was named Rastrelliger  brachysoma.  32  RASTRELLIGER BRACHYSOMA  Figure.  4  Sexual  Dimorphisms. male  — — —  Figure.  5  female  Geographical Variations. —  —- f r o m the north coast of J a v a from Tg.  Satai a r e a  33 Geographic V a r i a t i o n s Comparisons were done on head depth, d o r s o v e n t r a l depth, dorsoanal depth, g r e a t e s t body depth and i n t e r o r b i t a l d i s t a n c e s i n c e these c h a r a c t e r s show n e i t h e r sexual dimorphism nor strong a l l o m e t r i c growth i n both s p e c i e s . A n a l y s i s o f covariance on the data i n d i c a t e d t h a t : 1.  between sympatric samples ( h o . 1 and no. 3; no. 2 and no. 4) these c h a r a c t e r s show a very h i g h l y s i g n i f i c a n c e d i f f e r e n c e (0.01%);  2.  the dorsoventral depth, g r e a t e s t body depth, and i n t e r o r b i t a l d i s t a n c e have s i g n i f i c a n c e i n t r a s p e c i f i c d i f f e r e n c e ' 5%), showing  geographical v a r i a t i o n s in-i?. braahysoma  (Table  20).  The f i s h from Tg. S a t a i area possess g r e a t e r d o r s o v e n t r a l depth, g r e a t e r body depth, and longer i n t e r o r b i t a l d i s t a n c e than i t s c o u n t e r p a r t from the north c o a s t o f Java. words the R. braahysoma  from the north coast o f Java i s more  s l e n d e r than t h a t one from Tg. S a t a i (Figure 3.  R. kanagurta  In other  5).  shows geographic v a r i a t i o n i n i t s head depth and  d o r s o v e n t r a l depth (Table  20).  The f i s h from the north c o a s t o f Java possess g r e a t e r head depth and d o r s o v e n t r a l depth.  So thus R. kanagurta  from  Tg. S a t a i i s s l e n d e r and has l e s s e r head depth than the one from the north coast o f Java ( F i g u r e 6 ) .  34 TABLE 11  Comparison o f Body P r o p o r t i o n s o f Rastrelliger spp. by Covariance A n a l y s i s Between Classmodes o f 20.0 cm Fork-Length 17.5 22.4 cm) and o f 16.0 cm Fork Length (14.5 - 17.4 cm) Taken from Tg. Satai Area Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr i s the v a r i a n c e r a t i o t o t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n difference. Fb t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . Fa t o t e s t the a d j u s t e d mean d i f f e r e n c e . In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the adjusted mean becomes i n a p p r o p r i a t e . Character M a x i l l a r y length Head depth Dorsoventral depth Dorsoanal depth Greatest body depth Perp. i r i s diameter Perp. pupil diameter Pectoral f i n length I n t e r o r b i t a l distance Pectoral breadth *  ** *** Note:  Fr  Fb  1.40 1.67 1.15 1.35 1.18 2.32* 1.29 1.58 1.12 3.27**  6.12* 1.51 0.09 0.81 1.54 13.97*** 14.34*** 4.03* 1.91 0.81  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l . The above species was named  Rastrelliger  kanagurta.  Fa 0.95 1.25 2.14 1.05 0.65 (2.54) (2.84) 0.68 0.53 0.07  35 TABLE 12 Comparison o f Body P r o p o r t i o n s o f Rastrelliger spp. by Covariance A n a l y s i s Between Classmodes o f 20.0 cm Fork-Length (17.5 22.4 cm) and o f 14.0 cm Fork-Length (13.5 - 14.4 cm) Taken from Tg. S a t a i Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr i s the v a r i a n c e r a t i o to t e s t the s i g n i f i c a n c e o f the regression difference. Fb t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . Fa t o t e s t the adjusted mean d i f f e r e n c e . In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the a d j u s t e d mean becomes i n a p p r o p r i a t e . Character  Fr  Fb  Maxillary length Head depth Dorsoventral depth Dorsoanal depth G r e a t e s t body depth Perp. i r i s diameter Perp. P u p i l diameter Pectoral f i n i l e n g t h Interorbital distance P e c t o r a l breadth  1.56 1.40 1.04 2.03 2.88 2.62 1.07 1.19 1.37 2.29  0.67 0.91 0.52 0.06 0.01 2.27 0.001 1.49 1.55 0.10  * ** *** Note:  Fa  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l . The above s p e c i e s was named Rastrelliger  kanagurta.  12.20** 4.86* 0.58 0.17 0.12 13.87*** 21.83*** 8.17** 3.06 0.67  36 TABLE 13 Comparison o f Body P r o p o r t i o n s o f Rastrelliger spp. by Covariance A n a l y s i s Between Classmodes o f 16.00 cm Fork-Length (14.5 17.4 cm) and o f 14.00 cm Fork-Length (13.5 - 14.4 cm) Taken from Tg. Satai Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr Fb Fa In the  i s the v a r i a n c e r a t i o and i t s s i g n i f i c a n c e o f the r e g r e s s i o n difference. to t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . t o t e s t the a d j u s t e d mean d i f f e r e n c e . the case where the regression c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , t e s t o f the a d j u s t e d mean becomes i n a p p r o p r i a t e .  Character M a x i l l a r y length Head depth Dorsoventral depth Dorsoanal depth G r e a t e s t body depth Perp. i r i s diameter Perp. pupil diameter Pectoral f i n length I n t e r o r b i t a l distance Pectoral breadth  Fr  Fb  Fa  0.10 1.18 1.10 1.49 2.42 1.12 1.20 1.32 1.22 1.12  0.11 2.08 0.09 0.003 0.02 1.07 0.65 0.89 2.61 0.05  2.32 1.04 0.11 0.04 0.30 0.39 0.45 2.56 0.003 0.01  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l . Note:  The above species was named  Rastrelliger  kanagurta.  37 TABLE 14 Comparison o f Body Proportion o f Rastrelliger spp. by Covariance A n a l y s i s Between Sample No. 1 and Sample No. 2 from Jakarta and Tg. S a t a i respectively Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr i s the v a r i a n c e r a t i o to t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n difference. Fb t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . Fa t o t e s t the a d j u s t e d mean d i f f e r e n c e . In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the a d j u s t e d mean becomes i n a p p r o p r i a t e .  Character Head depth Dorsoventral depth Dorsoanal depth G r e a t e s t body depth Interorbital distance  * ** ***  Fr  Fb  1.15 1.65* 1.49 1.92* 1.82*  1.81 1.37 2.42 0.31 0.31  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l .  Fa 1.26 3.90 2.36 9.90** 1.15  38  TABLE 15 Comparison of Body Proportions of Rastrelliger spp. by Covariance Analysis Between Samples No. 3 (Jakarta) and No. 4 (Tg. Satai) Data show variance ratio and i t s significance. Fr  is the variance ratio to test the significance of the regression difference.  Fb to test the regression coefficient difference. Fa to test the adjusted mean difference. In the case where the regression coefficient difference is s i g n i f i c a n t , the test of the adjusted mean becomes inappropriate.  Character  Head depth Dorsoventral depth Dorsoanal depth Greatest body depth Interorbital distance  *  ** ***  Fr  1.05 1.28 1.05 1.07 1.19  Significant at 5% l e v e l . Significant at 1% l e v e l . Significant at 0.1% l e v e l .  Fb  Fa  1.20 5.89* 3.80 2.80 3.03  6.51* 1.54 2.23 0.39 0.84  39 TABLE 16 Comparison o f Body P r o p o r t i o n s o f Rastrelliger spp. by Covariance A n a l y s i s Between Samples No. 1 ( J a k a r t a ) and No. 3 (Jakarta) Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr i s the variance r a t i o to t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n difference. Fb t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . Fa t o t e s t the adjusted mean d i f f e r e n c e . In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the a d j u s t e d mean becomes i n a p p r o p r i a t e .  Character Head depth Dorsoventral depth Dorsoanal depth Greatest body depth Interorbital distance  *  ** ***  Fr 1.44 2.21* 2.31** 1.62 1.54  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l .  Fb 9.41** 28.92*** 14.83*** 17.26*** 5.26*  Fa (>D (>D (>D (>D  25.41***  40 TABLE 17 Comparison o f Body Proportions o f Rastrelliger spp. by Covariance A n a l y s i s Between Samples No. 2 (Tg. S a t a i ) No. 4 (Tg. S a t a i ) Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr Fb Fa  i s the v a r i a n c e r a t i o to t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n difference. t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . t o t e s t the adjusted mean d i f f e r e n c e .  In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the adjusted mean becomes i n a p p r o p r i a t e .  Character Head depth Dorsoventral depth Dorsoanal depth Greatest body depth Interorbital distance  *  ** ***  Fr 1.31 1.04 1.46 1.09 1.009  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l .  Fb 43.43*** 31.96*** 7.80** 31.39*** 0.03  Fa (>D  (>1) (>1) (>1) 19.82***  41  TABLE 18 Comparison o f Body P r o p o r t i o n s o f Rastrelliger spp. by Covariance A n a l y s i s Between Samples No. 2 (Tg. S a t a i ) and No. 3 ( J a k a r t a ) Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr  i s the v a r i a n c e r a t i o t o t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n difference. Fb t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . Fa t o t e s t the adjusted mean d i f f e r e n c e . In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f t h e a d j u s t e d mean becomes i n a p p r o p r i a t e .  Character Head depth Dorsoventral depth Dorsoanal depth G r e a t e s t body depth Interorbital distance  * ** ***  Fr 1.25 1.34 1.54 1.18 1.18  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l .  Fb 27.65*** 38.75*** 11.73*** 28.36*** 2.93  Fa ( 1) ( 1)  W\  9.87**  42 TABLE 19 Comparison of Body Proportions o f Rastrelliger spp. by Covariance A n a l y s i s Between Samples No. 1 ( J a k a r t a ) and No. 4 (Tg. S a t a i ) Data show v a r i a n c e r a t i o and i t s s i g n i f i c a n c e . Fr Fb Fa  i s the v a r i a n c e r a t i o to t e s t the s i g n i f i c a n c e o f the r e g r e s s i o n difference. t o t e s t the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e . to t e s t the adjusted mean d i f f e r e n c e .  In the case where the r e g r e s s i o n c o e f f i c i e n t d i f f e r e n c e i s s i g n i f i c a n t , the t e s t o f the a d j u s t e d mean becomes i n a p p r o p r i a t e .  Character Head depth Dorsoventral depth Dorsoanal depth Greatest body depth Interorbital distance  *  ** ***  Fr 1.52 1.72* 2.18** 1.75* 1.84*  S i g n i f i c a n t a t 5% l e v e l . S i g n i f i c a n t a t 1% l e v e l . S i g n i f i c a n t a t 0.1% l e v e l .  Fb 9.84** 25.61*** 13.79*** 17.65*** 0.56  Fa ( ( ( (  1) 1) 1) 1)  54.49***  43  SAMPLE NUMBER  CHARACTER No.l Head depth Dorsoventral  No.2  depth  -  D o r s o a n a l depth Greatest  *  body depth  Interorbital  **  distance *  No. 2 **  Head depth Dorsoventral No. 3  ***  depth  D o r s o a n a l depth •if*-*  G r e a t e s t body depth *  i n t e r o r b i t a l distance  **  **# **-•)<•  Head depth Dorsoventral No.4  *  **  depth  Dorsoanal depth Greatest  body depth  Interorbital  *  *#* ***  distance Fr  Table  No. 3  Fb  Fa  ##* Fr  Fb  Fa Fr  Fb  Fa  20.Covariance a n a l y s e s f o r p a i r s o f R a s t r e l l i g e r . F r , Fb and F a a r e t h e v a r i a n c e r a t i o s used t o t e s t the significance of difference i n regression line, regression c o e f f i c i e n t and a d j u s t e d mean r e s p e c t i v e l y . *  : Significant  ** : *** :  "  11  at 5  1 0.1  7* l e v e l . "  io fo  "  RASTRELLIGER  Geographical  KANAGURTA  Variations.  • f r o m T g . Satai a r e a - f r o m the north coast of J a v a  45 3. M e r i s t i c Characters Number o f Vertebrae T o t a l numbers o f v e r t e b r a e appeared to be constant as a l l specimens examined had 31 v e r t e b r a e . 26 specimens o f 7 - 9 cm FL possessed 31 v e r t e b r a e . There i s no d i f f e r e n c e i n vertebrae number between R. and R.  braahysoma  kanagurta.  F i r s t Haemal Spine The f i r s t haemal s p i n e appeared constant on the tenth v e r t e b r a e in  Rastrelliger.  Sample no. 1, i . e . , R. braahysoma  from t h e north c o a s t o f  Java have a mean o f the f i r s t haemal spine l o c a t i o n o f 9.9 (0.3 S.D.) with c o e f f i c i e n t o f v a r i a t i o n 3.1%. Sample no. 2, no. 3, and no. 4 appeared constant on the tenth vertebrae. F i r s t Dorsal Spine The f i r s t d o r s a l f i n spine counts appeared v a r i a b l e between 10.6 (0.5 S.D.) t o 11.0 (0.0 S.D.). Analysis o f variance indicated highly significant (1%) between R. kanagurta Tg. S a t a i a r e a .  differences  from the north c o a s t o f Java and t h e one from  The f i s h from the former area has e l e v e n spines on  i t s f i r s t d o r s a l f i n , whereas the one from the l a t t e r area i s v a r i a b l e ,  46 e i t h e r possessing eleven o r t e n spines (x = 10.6, S.D. = 0.5, n = 20). Dorsal F i n Rays and F i n l e t s The second dorsal f i n rays plus f i n l e t s counts appear t o be l e s s v a r i a b l e . The c o e f f i c i e n t o f v a r i a t i o n ranged from 0.0 t o 2.9%. There i s no s i g n i f i c a n t d i f f e r e n c e between s p e c i e s . The f i n - r a y s vary  from 12 t o 13 and the d o r s a l f i n l e t s  from 5 t o 6. Anal F i n Rays and F i n l e t s The counts o f anal f i n rays and anal f i n l e t s appeared c o n s t a n t , i . e . , 18. The f i n - r a y s a r e 13 and the anal f i n l e t s v a r y  between 5  and 6. F i r s t Occurrence o f Haemal Brace The f i r s t haemal brace occurred as a s t r u c t u r e on vertebrae as d e s c r i b e d by Roedel (1952) ( F i g u r e 7 ) . He suggested t h a t t h i s c h a r a c t e r i s good f o r d i s t i n g u i s h i n g race i n  Pneumatophorus.  The f i r s t occurrence o f haemal brace i n Rastrelliger  appeared  on e i t h e r the t h i r t e e n t h o r the f o u r t e e n t h v e r t e b r a e . The c o e f f i c i e n t o f v a r i a t i o n range from 2.2 t o 3.6. The means range from 13.7 (0.5 S.D.; n = 20) t o 13.9 (0.3 S.D.; n = 2 0 ) .  Figure  7. F i r s t Occurence o f Haemal Brace on V e r t e b r a e ( a f t e r Roedel, 1 9 5 2 ) . 1. P a r t i a l l y Formed Brace 2. Haemal Brace  48 TABLE 21 G i l l Raker Counts o f  Species Name  Rastrelliger  Part o f G i l l Arch  Mean  S.D.  Coefficient of Variations  N  R.  braahysoma  Upper Lower Total  19.0 35.8 55.0  1.0 0.9 1.0  5.47 2.46 1.82  14 25 15  R.  kanagurta  Upper Lower Total  20.6 36.6 57.2  1.3 1.0 1.9  6.27 2.73 3.27  28 30 28  TABLE 22 The Degree o f I n t e r g r a d a t i o n o f the T o t a l G i l l Raker Counts of the F i r s t L e f t G i l l Arch o f Rastrelliger G i l l Raker Count  54  55  56  57  58  59  n  26.7  26.7  6.6  -  -  100  7.1  10.7  21.4  25  Species R.  braahysoma  40  R.  kanagurta  14.3  Intergradation  = 19%.  21.4  99.9  49 A n a l y s i s o f v a r i a n c e i n d i c a t e d t h a t there i s no s i g n i f i c a n t d i f f e r e n c e between and w i t h i n s p e c i e s . T h e r e f o r e , t h i s c h a r a c t e r cannot be used i n r a c i a l s t u d i e s o f Rastrelliger  spp.  G i l l Raker The g i l l raker counts on the f i r s t l e f t g i l l arch show c o n s i d e r a b l e v a r i a t i o n s . The c o e f f i c i e n t o f v a r i a t i o n o f the g i l l r a k e r counts on the lower limb i n R. kanagurta 1.0); i n R. braahysoma  was 2.7, and the mean was 36.6 (S.D. =  was 2.5 and 35.8 (S.D. = 0.9) r e s p e c t i v e l y . Those  values o f the upper limb were 6.3 and 20.6 (S.D. = 1.3); and 5.5,  19.0  (S.D. = 1.0). The t o t a l g i l l r a k e r counts on the f i r s t l e f t g i l l arch show o v e r l a p between s p e c i e s ; the degree o f i n t e r g r a d a t i o n was 19% (Tables 21, 22).  4.  Q u a l i t a t i v e Characters Colouration No d i s t i n c t d i f f e r e n c e s e x i s t i n body c o l o u r a t i o n among  samples. The dark spots or s t r a y spots below the f i r s t d o r s a l and on the t i p and o u t e r margin o f the f i r s t dorsal f i n show a s l i g h t d i f f e r e n c e i n the degree o f darkness between fi. braahysoma  and R. kanagurta.  The  former s p e c i e s possesses darker c o l o u r on i t s t i p and outer margin o f the f i r s t d o r s a l f i n , whereas the second one has c l e a r e r l o n g i t u d i n a l bands above the l a t e r a l l i n e s .  50  Cephalic L a t e r a l Line Canal There i s an apparent d i f f e r e n c e i n t h e appearance o f t h e c e p h a l i c l a t e r a l l i n e system between t h e two s p e c i e s . R. braahysoma  system; whereas  R.  possesses a very f i n e l y d e n d r i t i c canal  kanagurta  has a l e s s f i n e l y d e n d r i t i c one ( F i g u r e  T h i s c h a r a c t e r i s u s e f u l i n d i s t i n g u i s h i n g s p e c i e s , and can be used as a key c h a r a c t e r s . Digestive Tract The d i g e s t i v e t r a c t i n ed than t h a t o f  R. kanagurta.  R.  braahysoma  i s much more convolut-  T h i s d i f f e r e n t appearance i s r e l a t e d  t o t h e longer i n t e s t i n e i n t h e f i r s t s p e c i e s . The shape o f t h e stomach d i f f e r s o n l y i n t h e presence o f a small f l a p p y t i p a t t h e bottom o f t h e stomach o f  R.  kanagurta  (Figure 9 ) . 5. P o p u l a t i o n Study Rastrelliger Rastrelliger  Fisheries i s f i s h e d i n p r a c t i c a l l y a l l c o a s t a l areas o f  Indonesia; and i s caught maily by payang-net. The payang net i s an e n c i r c l i n g s u r f a c e seine with a bag, and have the upper l i n e s . s h o r t e r than t h e lower ones. The fishermen u s u a l l y use a l u r e that i s c a l l e d rumpon to a t t r a c t t h e f i s h and concentrate them. The payang-net i s  8).  51 dragged passing underneath o r a l o n g s i d e t h e rumpon and i s hauled up t o the v e s s e l . The o p e r a t i o n takes place during the day. Thousands o f such rumpons l i e s c a t t e r e d over t h e Java Sea. Several f i s h i n g gears such as shore s e i n e , g i l l n e t , and traps are u t i l i z e d along the c o a s t a l areas. In the l a t e p a r t o f 1971, the purse seine was introduced i n the Bay o f J a k a r t a .  I t has operated economically s i n c e 1972 i n the  c o a s t a l areas o f t h e north coast of Java. The f i s h caught c o n s i s t o f two s p e c i e s , R. brachysoma  or  Kembung Perempuan which i s caught mainly i n the c o a s t a l zones; and R. kanaguvta  o r Kembung L e l a k i o f the o f f s h o r e areas.  The major p a r t o f landings comes from t h e Sunda S h e l f area, i n p a r t i c u l a r t h e north coast of Java, the south and the south west coasts o f Borneo (Kalimantan) and the east c o a s t o f Sumatra. The production i n the north coast o f Java i s estimated as exceeding 10,000 tons per y e a r , o f which t h e g r e a t e r p a r t o f the l a n d i n g c o n s i s t s o f R. kanaguvta  (Table 23).  In t h e e a s t e r n part o f Indonesia the f i s h i n g a c t i v i t i e s are not y e t developed.  Population  Parameters  The present study o f Rastrelliger  p o p u l a t i o n dynamics  i n Indonesian waters begins with a n a l y s i s o f v a r i a b l e s or parameters of i t s populations.  D e t a i l e d analyses o f v a r i a b l e s a f f e c t i n g y i e l d  have been attempted i n the G u l f o f T h a i l a n d and Indian waters.  52  Figure  8.  C e p h a l i c L a t e r a l L i n e System o f R a s t r e l l i g e r . II.  R» brachysoma R. k a n a g u r t a  A b b r e v i a t i o n s : CL, c e p h a l i c l a t e r a l i s ; ' F, f r o n t a l ; 10, i n t e r o r b i t a l ; LL, l i n e a l a t e r a l i s ; POC, p o s t o c u l a r commisure; SO, s u p r a o r b i t a l ; ST,supratemporal.  53  Figure  9.  D i m e n s i o n of m e a s u r e m e n t tract of R a s t r e l l i g e r .  of the digestive  1. stomach;  intestine.  I.  2.  p y l o r i c ; 3.  ths stomach of R .  II. the stomach of R.  brachysoma kanagurta  54 TABLE 23 Production o f Payang F i s h e r i e s i n the North Coast o f Java o f R. kanagurta  1969 (tons)  1970 (tons)  1971 (tons)  I  210  275  535  II  203  358  521  III  408  528  863  IV  849  1,093  1,156  V  547  645  1,003  VI  499  528  934  VII  431  562  739  VIII  438  424  588  IX  551  593  869  X  725  735  1,011  XI  802  774  1,033  XII  509  584  906  6,172  7,099  10,158  Month  Total  Sources: (1) The Sea F i s h e r i e s S e r v i c e o f Jakarta-Raya i n J a k a r t a , (2) " o f the Province o f West Java i n Bandung, (3) " o f t h e P r o v i n c e o f Middle Java i n Semarang, (4) " o f the P r o v i n c e o f East Java i n Surabaya.  55 The i n f o r m a t i o n a v a i l a b l e does not meet the data requirement of modern management models. Moreover, some d i f f i c u l t i e s such as und e t e c t a b l e growth r i n g s on s c a l e s and o t h e r s k e l e t a l s t r u c t u r e s , v a r i a b i l i t y i n growth r a t e s , i n d e f i n i t e spawning periods and the p a u c i t y o f catch s t a t i s t i c s lead to a t b e s t , approximate e s t i m a t i o n s of parameters. However, the r e s u l t s r e p o r t e d here compare f a v o u r a b l y with the r e s u l t s obtained by v a r i o u s i n v e s t i g a t o r s from the adjacent r e g i o n s .  Sexual C o n d i t i o n s Maturity The importance o f age at sexual m a t u r i t y f o r management purposes i s obvious.  N i k o l s k i i (1969) s t a t e s t h a t because o f d i f f e r -  ences i n growth r a t e s , young hatched at the same time w i l l reach m a t u r i t y at d i f f e r e n t ages.  Sexual m a t u r i t y may be governed by  attainment of a c e r t a i n s i z e r a t h e r than age.  The s i z e a t m a t u r i t y i s  t h e r e f o r e an important parameter i n management, e s p e c i a l l y f o r t r o p i c a l s p e c i e s , wherein e x p l o i t a t i o n should allow an adequate number of spawners, i . e . , l a r g e r than o r equal to the s i z e at sexual m a t u r i t y , to assure a continued supply o f young f i s h . The data suggest t h a t Rastvelligev  kanaguvta  i n the Java  Sea a t t a i n s i t s sexual m a t u r i t y at 19.0 (18.0 - 20.5) cm TL about  or at  7 months of age ( F i g u r e 29 i_n Appendices, T a b l e 27). Chidambaram and Venkataraman (1946) found the minimum s i z e  at sexual m a t u r i t y of R. kanaguvta  i n Indian waters to be 20 cm.  56 In t h e same waters Pradhan (1956) suggested 22.4 cm TL a t m a t u r i t y . P a t h a n s a l i (1966) reported that R. kanagurta  caught a t Pangkor I s . ,  M a l a y s i a , a t t a i n e d sexual m a t u r i t y a t 17.5 - 19.8 cm. The s i z e a t mat u r i t y o f t h e same f i s h i n waters o f the P h i l i p p i n e was recorded as 21.0 - 21.9 cm ( P h i l i p p i n e s F i s h e r i e s Handbook, 1952).  Tiews (1958)  g i v e s 18.0 cm f o r t h i s f i s h i n t h e same r e g i o n . No records a r e a v a i l a b l e from t h e o t h e r r e g i o n s o f t h e I n d o - P a c i f i c area. R. braahysoma  a t t a i n s i t s sexual m a t u r i t y a t 17.3 (17.0 -  17.5) cm TL o r about 7.5 months o l d ( F i g u r e 11, Table 28). The o n l y other comparable data f o r t h i s s p e c i e s were obtained i n Manila Bay, The P h i l i p p i n e s , where the s i z e a t m a t u r i t y was 15.0 16.9 cm ( P h i l i p p i n e s F i s h e r i e s Handbook, 1952); Tiews (1958) g i v e s 16.5 cm. Beverton (1963) s t u d i e d the age a t m a t u r i t y o f c l u p e i d s and e n g r a u l i d s and s t a t e d t h a t f i s h with high K value (von B e r t a l a n f f y growth parameter) mature a t an e a r l i e r age than f i s h with low K. The data suggest that Rastrelliger  f o l l o w t h i s p a t t e r n . R.  kanagurta  with a higher K value (= 0.23) mature a t a younger age (= 7 months) than  R. braahysoma  with a lower K value (= 0.19) that mature a t 7.5  months o l d (Table 26, 27, 28; F i g u r e 11, 29 i_n Appendices).  Gonads Several i n d i c a t o r s o f the m a t u r i t y stages a r e a v a i l a b l e e i t h e r f o r the f i e l d or l a b o r a t o r y . These keys have been d e s c r i b e d by Indian workers and were developed from The Key t o the Stages o f Sexual M a t u r i -  57 ty of the Herring by the I n t e r n a t i o n a l Council f o r the E x p l o r a t i o n o f the Sea (Pradhan and P a l e k a r , 1956). In t h i s study the f i e l d keys were employed (Table 24, 25). No f e c u n d i t y study has been c a r r i e d out. Devanesan and John (1940) estimated an average o f 94,000 eggs per female R.  kanaguvta  i n Indian waters. Boonprakob (1966) estimated 86,000 eggs per female f o r advanced group eggs and 479,000 eggs per female f o r t o t a l ova of the same s p e c i e s caught i n the G u l f o f T h a i l a n d .  For R.  bvachysoma  he estimated 100,000 - 166,000 eggs per female f o r advanced group and 200,000 - 500,000 eggs per female f o r t o t a l ova. Furthermore, he w r i t e s that R. kanaguvta chysoma  r e l e a s e d 20,000 eggs per batch and R. bva-  between approximately 20,000 and 30,000 eggs per batch.  Spawning The mature gonads o f R. kanaguvta  are found mostly i n  January and May (Figure 10), but there i s evidence t h a t stage IV (mature) gonads are found i n September.  The data suggest t h a t i n  the Java Sea t h e r e are two spawning seasons, the f i r s t during the West Monsoon probably from October to February and the second during the East Monsoon from June to September. P a t h a n s a l i (1961) assumed that the spawning season o f R. kanaguvta  on the west coast of M a l a y s i a i s from October to A p r i l .  Jones and Rosa (1962) s t a t e d that the spawning season o f t h i s f i s h i n Indian waters appears to be from March to September.  58  TABLE 24 F i e l d Key o f M a t u r i t y Stages o f  Rastrelliger  (Males) Extent o f Testes i n Body C a v i t y  General Appearance o f Testes Stage and S t a t e  Less than 1/2 l e n g t h of c a v i t y  Very small t r a n s l u c e n t o r whitish strand visible  S l i g h t l y more than 1/2 length o f c a v i t y  D i s t i n c t o v o i d o r elongate f l a t body v i s i b l e ; mostly translucent; whitish  About 2/3 o r over length o f c a v i t y  Opaque; white and f l a t ; sometimes creamy  Much over 2/3 t o f u l l length o f c a v i t y  Opaque; white; s o f t ; sperm extrusable  Much reduced i n s i z e , about 1/3 o f c a v i t y  Bloodshot and f l a b b y , p a r t l y translucent  Note:  For Fresh M a t e r i a l .  I Immature II Maturi ng III Maturing IV Mature V Spent  59 TABLE 25 Field Key of Maturity Stages of  Rastrelliger  (Females)  Extent of Ovary in Body Cavity  General Appearance of Ovary  Stage and State  About 1/3 length of cavity  Translucent; redish to pinkish in colour; ova i n v i s i b l e  I Immature  About 1/2 length of cavity  Translucent; pinkish in colour; ova i n v i s i b l e  II Maturing  About 2/3 length of cavi ty  Pinkish yellow colour; granular, opaque in appearance  III Maturing  Over 2/3 to f u l l length of cavity  Orange to pink in colour; superficial blood vessels conspicuous; translucent eggs v i s i b l e ; ripe eggs are extrusable  Shrunken to about 1/2 length of cavity; walls loose  Remnant of disintegrating opaque and ripe ova v i s i b l e ; may be dark red or translucent  Note:  For Fresh Material.  IV Mature  V Spent  60 R. bvachysoma  from Tg. S a t a i appears t o have a long spawning  season t h a t l a s t s from May to October. T h i s c o n c l u s i o n i s based upon the m a t u r i t y stages data ( F i g u r e 11) and the disappearance o f t h i s f i s h f o r several months d u r i n g which time they migrate from the area to spawn. In the G u l f o f T h a i l a n d , Boonprakob (1966) r e p o r t e d t h a t the spawning season o f R. braohysoma  i s from January to August.  Druzhi-  nin (1968) s t a t e s t h a t i n Burma waters the same s p e c i e s has a spawning season t h a t l a s t s from September to May. Jones and Rosa (1962) s t a t e t h a t Rastrelliger  spawn i n  s u c c e s s i o n over a prolonged p e r i o d and o n l y a small p o r t i o n o f ova mature each time g i v i n g a " s p e c k l e d " appearance stage. P a t h a n s a l i (1966) s t a t e s t h a t t h e r e i s c o n s i d e r a b l e d i f f e r e n c e i n the m a t u r i t y stages of R. kanagurta  o v a r i e s w i t h i n f i s h of the same school and  i n the same s i z e range. T h i s r e s u l t e d i n p e c u l i a r modes o f egg r i p e n ing and spawning.  As the spawning o f any one batch o f ova i s not  simultaneous i n a l l f i s h , a number o f broods are produced during each r e p r o d u c t i v e season. Boonprakob (1966) suggested t h a t a spawner o f R.  braohysoma  a f t e r r e l e a s i n g the f i r s t batch of eggs probably r e l e a s e s subsequent batches o f eggs a t s h o r t i n t e r v a l s o f time. Evidence o f repeated spawning i s not unusual i n the f a m i l y Scombridae. japonicus  Fry (1936) i d e n t i f i e d repeated spawning i n  Scomber  which he says may spawn two or more times a season.  The  spawning season i s from A p r i l to August and occurs o f f the C a l i f o r n i a Coast.  61  40-  Nov.71  Jun.7?  Dec.71  Jul.72  Jan.72  Aug.72  Feb.72  Ser>.72  20  4020 04G2G CUC  2G C4C 2C C  May.72  4C 2C  i nniy/T Figure  1  IffllTY  10. S e x u a l M a t u r i t y Stages Com-oosition o f R. kanagurta from the n o r t h c o a s t o f Java,  62  Sexual Maturity  17 Figure  n  18  19  20  Stage  21  TL  (cm)  Length end S e x u a l M a t u r i t y Stage Compositions o f R. brachysoma from T g . S a t a i , on March 1°72.  63 If t h e number o f batches can be determined, t h e time taken by each batch t o develop could be determined which i n t u r n would a l l o w one t o measure t h e l e n g t h o f the breeding season. Without knowledge o f a d e f i n i t e breeding season i t i s d i f f i c u l t t o determine annual r e cruitment and t o r e l a t e r e c r u i t s to the broods o f young i n one y e a r . Repeated spawning w i t h i n a y e a r c r e a t e s sub-year c l a s s e s , possessing d i f f e r e n t growth r a t e s , which causes o v e r l a p s i n t h e l e n g t h frequency d i s t r i b u t i o n making t h e d i f f e r e n t age groups d i f f i c u l t t o identify. Fry (1936) s t a t e s t h a t Scomber scombrus  spawns i n water  deeper than 70 meters, with a temperature range o f 16.7 t o 20.6° C. He found p e l a g i c eggs o f s. japonicus  f l o a t i n g a t o r near t h e sur-  f a c e i n t h e open sea. Bigelow and Welch (1925) found eggs i n water temperature ranging from  4 to 17.8° C with s a l i n i t y from  31.9 to  33.0 °/oo. The s u r f a c e ( < 10 m) temperature i n t h e Java Sea and adjacent areas i n January, February, and March  ranges from 27.5 -  29.0° C, and the s a l i n i t y ranges from 32.0 - 33.0 °/oo. May, and June  t h e temperature i s approximately 29.0°C  s a l i n i t y approaches 34.25 °/oo).  In A p r i l , and t h e  33.5 °/oo ( i n t h e e a s t e r n p a r t o f Java Sea i t i s  These c o n d i t i o n s continue throughout  J u l y , August,  and September, except i n t h e e a s t e r n p a r t o f t h e Java Sea where s a l i n i t y i s s l i g h t l y higher.  In October, November, and December the  temperature' and s a l i n i t y decrease to 27.5° (the western edge o f t h e Java Sea: 27.5 - 29.0°) and 32.5 °/oo (the e a s t e r n p a r t o f t h e Java Sea ranges from 33.5 - 34.5 °/oo) ( B a r k l e y , 1968).  64  The s a l i n i t y in the coastal areas is generally lower than that of the offshore due to the inflow of rivers.  This condition  might prevent egg development as they need water of high density for the osmotic requirements of the eggs. If  Rastrelliger  spawns in the same depth as Scomber  they  must migrate to deeper waters from the Java Sea area (where the depth does not exceed 50 m).  These areas could be the South China Sea,  the Indian Ocean or the eastern part of the Java Sea adjacent to the Flores Sea.  I suspect that the West Monsoon population spawns in the  South China Sea or the Indian Ocean, and the East Monsoon population in the Flores Sea. Egg and larval studies in the above areas and in the Java Sea might help elucidate the spawning behaviour of  Rastrelliger.  Sex Ratio The males and females of  R. kanagurta  in the commercial  catches  exist in approximately equal proportions with a ratio of 1.0  to 1.1.  The unpublished data of the Institute for Marine Research  in Jakarta show that in the West Monsoon (1971/1972) the ratio is 1.0 to 1.2 and in the East Monsoon (1972) i t is about equal. waters,  In Indian  Jones and Rosa (1962) observed a ratio of 1.0 to 1.0. In  R. braahysoma the ratio is 1.3 to 1.0 (1972); whereas  Druzhinin (1968) recorded a ratio of 1.0 to 1.7 between males and f e males in Mergui Arch., Burma.  65  !  Longevity The data suggest that R. kanaguvta  in the Java Sea can  attain 24.0 cm TL or 3 years of age (Table 26, 27). In unpublished data of the Marine Fisheries Research I n s t i - ' tute in Jakarta, Kadir (1966) recorded a specimen of 26.5 cm caught in the south west of Borneo.  The largest specimen caught in Indian  waters was 27.0 cm (Jones and Rosa, 1962).  De Beaufort (1951) record-  ed a length of 37.0 cm. R . bvachysoma 26,  28).  can reach 23.0 cm TL or 3 years of age (Table  In the Gulf of Thailand i t is recorded as 21.0 cm and de  Beaufort (1951) recorded 21.9 cm.  Environmental Tolerance Although there is no d e f i n i t i v e study concerning the hardiness of these f i s h ,  some information.is  available from  various  investigations.. Pradhan (1956) writes that  R. kanaguvta  can withstand low  s a l i n i t y of 2.04 °/oo but without stating the duration.  Jones and  Rosa (1962) write that the f i s h are known to enter estuarine water of Kali River, India, and ascend along the tidal current to a distance of more than 2 km during the month of April and May when the range of s a l i nity is 29.7 - 34.6 °/oo. tvelligev  Moreover, they stated that the genus  Ras-  i s distributed in the Tropical Indo-West Pacific Faunistic  Region only; i t does not extend eastward to the East Pacific Barrier. Oceanographically the former region possesses a high surface tempera  66  ture which does not f a l l below 17°C i n any season and a t the 200 m i s o b a t h the temperature i s 15°C. Pradhan and Gangadhara (1962) s t a t e t h a t R. kanagurta  appears  to be more s u c c e p t i b l e to changes i n temperature than s a l i n i t y .  The  t o l e r a n c e to these f a c t o r s depends upon the s i z e o f the f i s h i n t h a t l a r g e r f i s h are more r e s i s t a n c e to a higher temperature and s a l i n i t y . Competitor and Predator The scads (Decapterus  spp.) and the o i l - s a r d i n e s (Sardinella  spp.) seem to be the most important competitors f o r food. . The f i s h e s , l i k e Rastrelliger,  are plankton f e e d e r s .  The tuna and t u n a - l i k e f i s h e s (Katsuwonus nus  spp.), sharks and porpoises a r e Rastrelliger  spp. and  Euthyn-  predators.  Parasites U n i d e n t i f i e d nematodes were recovered from the body c a v i t y of R. kanagurta  but none from  R.  braahysoma.  Several Indian i n v e s t i g a t o r s recorded trematode, cestode, and copepode p a r a s i t e s i n R. kanagurta  ( S i l a s , 1962).  Growth Growth i s manifested as an i n c r e a s e i n the s i z e of an organism.  The best measurement i s  weight.  However, s i n c e accurate  weighing i s not e a s i l y done at sea, growth can be determine from length data; t h e r e f o r e , the length-weight r e l a t i o n s h i p i s necessary. The methods used i n growth s t u d i e s are g e n e r a l l y i n v o l v e d :  .  67 J  tracing the seasonal or annual increase in mean or modal length of  successive age groups in the population; - the back calculation method of Petersen (1891), i . e . , by taking measurement of skeletal structures, usually scales (Lea, 1910) or otoliths (Hickling, 1933); - by tagging, i . e . , by measuring the increase in length of tagged f i s h between capture and recaptures. The f i r s t method gives the average growth characteristics of a population and the last two methods give growth data for i n d i v i - . dual f i s h , or the last one can also be used to provide data to supplement the other methods. George and Bannerji (1964) used the f i r s t method to study the age and growth of Rastrelliger  kanagurta  in India and Hongskul (1972)  combined the f i r s t and the third methods to study the population dynamics of R. braohysoma  in the Gulf of Thailand.  In this study the modal progression method as described by George and Bannerji (1964) was employed.  The main d i f f i c u l t y in deter-  mining length frequency distributions was caused by the prolonged and fractional spawning season. Another important consideration involves determining the age of f i r s t appearance.  To obtain an accurate estimation, larval and  juvenile studies must be conducted.  Larval collections have been done  in India, but did not involve growth and age studies.  Growth Model  68 The well known Von B e r t a l a n f f y ' s (1934) model was employed. The method o f f i t t i n g has been d e s c r i b e d by Beverton and Holt (1957), R i c k e r (1958), and o t h e r s . In t h i s study a computer program developed by A l l e n and d i f i e d by Wilimovsky  (1972) was used ( F i g u r e 12, 13).  The l e n g t h at any time l where:  l L  t  t  mo-  = L  (1 - e "  t i s g i v e n by: "  K ( t  the length at time  V)  t  the asymptotic length that i s the value of 1 assuming age i n c r e a s e s i n d e f i n i t e l y  K  the c o e f f i c i e n t of growth r a t e at which a f i s h approaches  t  i t s maximum length  the h y p o t h e t i c a l time at which the l e n g t h of a f i s h would have been zero.  Von B e r t a l a n f f y growth parameters obtained i n the Indo-Pacif i c Regions show c o n s i d e r a b l e v a r i a b i l i t y (Table 26).  The i n c o n s i s -  tency among the estimations from v a r i o u s i n v e s t i g a t o r s may p a r t l y d e r i v e from the v a r i a b i l i t y of samples, average modes employed, and probably the o v e r l a p p i n g lengths i n the l a t e ages, as growth s i g n i f i c a n t l y decreases c r e a t i n g poly-age groups.  The l a s t reason may have  r e s u l t e d i n an over estimate of the growth r a t e . Hongskul (1972) s t a t e s that those parameters obtained from tagging data and modal p r o g r e s s i o n method a n a l y s i s are n e a r l y the same.  ITTING OF VON EERTALANFFY GROWTH EQUATION  KEM3LNG PEREMPUAN (RASTRELLIGER BRAGHYSOM/ 20.0  ,  0.0  0.9  1.8  2.8  3.7  4.6  5.5  6.4  7.3  8.3  9.2  10.1  (month)  F i g u r e 12  Growth Curve o f R. braohysoma. Abscissa-age i n months; ordinate-!ength i n cm. (IBM 1130, CALCOMP 565)  11.0  FITTING OF VON BERTALANFFY GROWTH EQUATION KEMBUNG LELAKI (RASTRELLIGER KANAGURTA) 22.4  +  Figure 13  Growth Curve o f R. kanagurta. Abscissa-age i n months; o r d i n a t e - l e n g t h i n cm. (IBM 1130; CALCOMP 565)  71 TABLE 26 Von B e r t a l a n f f y Growth Parameters o f Rastrelliger from Various Authors and L o c a l i t i e s i n t h e I n d o - P a c i f i c Region Species  Author-Year-Locality  K  *o  (month) R.  R.  kanagurta  kanagurta  (cm)  - Cochin  0.43  21.77  - Calicut  0.26  23.26  - Karwar  0.36  22.40  Pooled  0.30  22.84  S u d j a s t a n i (1973) 0.23  0.92  (0.02) (.13 SE) (SE)  23.89 (.52 SE)  Hongskul (1972) - the G u l f o f T h a i l a n d  R. braahysoma  oo  George and Banerji (1964)  - Java Sea  R. negleotus (braahysoma)  L  0.28  -0.03  20.91  0.19  0.10  22.92  S u d j a s t a n i (1973) - Java Sea  (0.02) (SE)  (.18 SE) (.76 SE)  72 The estimated parameters o f the Von B e r t a l a n f f y model o f from the Java Sea a r e : R.  K *0  L  kanagurta  R.  braahysoma  0.2316 (0.0176 S.E.)  0.1885 (0.0187 S.E.)  0.9182 (0.1294 S.E.)  0.0993 (0.1817 S.E.)  23.8886 (0.5186 S.E.)  22.9170 (0.7638 S.E.)  month cm  The Point o f I n f l e c t i o n on t h e Growth Curve T h e o r e t i c a l l y a s t a b i l i z e d f i s h population has i t s maximum y i e l d i n f l u e n c e d by the nature o f growth and depends on the r a t e s o f natural and f i s h i n g m o r t a l i t y ( T e s t e r , 1952). As i t i s known t h a t a f i s h has maximum change i n weight a t the i n f l e c t i o n p o i n t , then, i t i s necessary to know the p o s i t i o n o f the i n f l e c t i o n p o i n t on the growth curve.  T e s t e r d e s c r i b e s three types of growth curves, the growth  curve with the i n f l e c t i o n p o i n t i n the e a r l y o f l i f e , about m i d - l i f e , and l a t e i n l i f e . Rational management and e x p l o i t a t i o n o f a f i s h species r e q u i r e s knowledge o f the i n f l e c t i o n p o i n t p o s i t i o n i n the growth curve p r i m a r i l y i n i t s r e l a t i o n s to the age at sexual  maturity.  Ssentongo (1971) generated a formulae t h a t d e r i v e d from the Von B e r t a l a n f f y ' s growth equation to determine t h e age a t the i n f l e c t ion point.  It i s :  73 t. i.p. n  where:  t.  = 1/K In b + t  o  is the age at the inflection point.  I • [J •  b  is the length-weight exponent  The inflection point of Rastrelliger  kanagurta  months (17.8 cm TL), whereas for R. braahysoma (15.1  cm TL).  is at the 5.9  i t is at 5.7 months  Both species have inflection points early in l i f e ,  meaning they attain their maximum growth increments before they reach the age at sexual maturity (7.0 and 7.5 months of age for R. and R. braahysoma Rastrelliger  respectively).  kanagurta  Thus, the exploitation of the  should be beyond the inflection point to allow sufficient  spawners (certain age classes).  The natural mortality coefficient of  the f i s h i s high, about 0.4, so that kind of exploitation could mean a loss of biomass.  However, the results of the Ricker Yield Model  suggest that at the present conditions where the age at f i r s t capture (t ) £  is 3.0 months for R. braahysoma  and 4.0 months for R.  kanagurta,  the exploitation w i l l hot endanger the populations since the stocks exhibit strong 7.0 - 8.0 months age classes (Tables 34, 35 and 36).  Behaviour Hardenberg (1938) states that Rastrelliger migrate.  are pelagic and  Their migration in the Java Sea follows the migration pattern  of the scad (Deoapterus  spp.) one of their competitors for food, but is  generally later by one or two weeks.  He describes that at the end of  74  the West Monsoon a stock o f oceanic Rastrelliger  i s present.  At the  beginning o f the East Monsoon the water o f the Java Sea begin to flow i n a w e s t e r l y d i r e c t i o n and the Rastrelliger d i r e c t i o n and disappears.  moves o f f i n a w e s t e r l y  A f t e r some weeks a new stock e n t e r s the  Java Sea through i t s e a s t e r n entrance.  At the end o f the East  Monsoon the reverse happens and two new stocks e n t e r the Java Sea, one from the north west out o f the South China Sea and one from the south west out o f the Indian Ocean. An attempt was made to prove t h i s hypothesis.  As was  d e s c r i b e d i n the previous s e c t i o n , there i s geographical v a r i a t i o n R. kanagurta  i n head depth and d o r s o v e n t r a l depth.  in  I suspect t h a t  these d i f f e r e n c e s suggest t h a t the two samples might come from two d i f f e r e n t p o p u l a t i o n s . Secondly, there are two spawning seasons i n t h i s a r e a , i . e . , from October to February ( i n the West Monsoon) and from June to September ( i n the East Monsoon). Moreover, the catch per u n i t o f e f f o r t and t o t a l e f f o r t r e l a t i o n s h i p ( F i g u r e 14) suggests t h a t there are two d i f f e r e n t populations i n v o l v e d i n one calendar y e a r .  The  f i r s t p o p u l a t i o n was present i n the months o f January, February, March, and reappeared i n September, October, November and December; while the second p o p u l a t i o n was present i n A p r i l , May, June, and J u l y . evidences support the hypothesis o f Hardenberg  These  (1938).  In a d d i t i o n to these m i g r a t i o n s , Rastrelliger  appears to  e x h i b i t l o c a l movement. Pradhan (1956) w r i t e s t h a t i n Karwar, I n d i a , during a n o r t h - e a s t e r l y wind, R. kanagurta  schools e n t e r inshore waters.  Jones and Rosa (1962) s t a t e t h a t s c h o o l s o f t h i s f i s h u s u a l l y move  75 CPUE  |-  2001  i  1  5  \  10  i  1  15  20  1  25 (X 1 0 0 0 )  1  TOTAL EFFORT  F i g u r e . 14. R e l a t i o n ^ b e t w e e n T o t a l E f f o r t ( T o t a l C a t c h / C a t c h per u n i t o f e f f o r t ) and C a t c h Per U n i t o f E f f o r t o f R. kanagurta from t h e n o r t h c o a s t o f Java, i n 1 9 7 1 (arable-numbers r e p r e s e n t e d months).West Monsoon East  Monsoon  76 with the c u r r e n t o f water a t high t i d e .  When there i s a s t r o n g  e a s t e r l y wind the schools come c l o s e to the shore through deeper l a y e r s o f water. The m i g r a t i o n o f R. braahysoma area.  was observed i n Tg. S a t a i  T h i s f i s h always disappears d u r i n g the months o f May to  October.  I t seems they migrate to somewhere nearby t h i s area to  spawn, s i n c e t h e i r gonads i n A p r i l are mostly mature. The l o c a l movement has a l s o been observed i n the G u l f o f T h a i l a n d area (Hongskul, 1972). The reason f o r t h i s phenomenon i s not y e t c l e a r , but Hardenberg (1955) s t a t e s t h a t t h i s f i s h tends to f o l l o w the h i g h e s t d e n s i t i e s of plankton. Age The a b i l i t y to determine the age o f f i s h i s an important tool i n f i s h e r i e s b i o l o g y and management. The e v a l u a t i o n o f age a l l o w s one to understand the age composition o f a f i s h p o p u l a t i o n and to determine the r o l e o f p a r t i c u l a r age c l a s s e s i n the f l u c t u a t i o n s . The e x i s t i n g p r i n c i p l e o f age d e t e r m i n a t i o n i s based on the r e c o g n i t i o n o f seasonal changes i n the form and composition o f s k e l e t a l s t r u c t u r e s o r o t h e r hard p a r t s which have been named growth marks o r growth checks.  Those marks are a r e s u l t o f f l u c t u a t i o n s i n the growth  o f the. f i s h . The ease and accuracy i n a p p l y i n g the p r i n c i p l e depends upon i t s e x i s t e n c e and r e g u l a r i t y .  Research on t h i s problem s t a r t e d almost  77 a hundred years ago.  R e i b i s c h (1899) was among the e a r l y i n v e s t i g a t o r s  to use o t o l i t h s , Heincke (1904) used bones and Dahl (1909) has d e s c r i b e d the method o f age determination  in detail.  I t i s known that the growth r a t e o f f i s h i s not uniform, even when t h e . e n t i r e l i f e c y c l e takes place i n an almost steady s t a t e c o n d i t i o n such as t h a t found i n t r o p i c a l waters. s o - c a l l e d seasonal v a r i a t i o n i n growth r a t e .  environmental  There i s a l s o t h e  This v a r i a t i o n w i l l be  expressed i n the hard parts o f the f i s h such t h a t periods o f r a p i d growth w i l l be i n d i c a t e d by wide zones and slow growth by narrow zones.  Generally,  i n the temperate zone, where i n winter the growth r a t e i s a t i t s minimum, the f l u c t u a t i n g p e r i o d i c i t y i s annual; whereas i n t r o p i c a l waters i t i s completely d i f f e r e n t . As e a r l y as Hoffbauer's  (1898) work on carp s c a l e s , t h e use  o f s c a l e s f o r age determination has depended upon the appearance o f recognizeable y e a r l y growth r i n g s c a l l e d a n n u l i . ent appearance i n d i f f e r e n t s p e c i e s .  Annuli have a d i f f e r -  In many species f a l s e annuli o r  accessory marks have been observed and sometimes they a r e d i f f i c u l t t o d i s t i n g u i s h from true a n n u l i .  Van Oosten (1957) s t a t e s t h a t these f a l s e  a n n u l i can be a t t r i b u t e d t o growth c e s s a t i o n caused by d i s e a s e , p a r a s i t i s m , i n j u r y , s t a r v a t i o n , o r a temporary drop o r r i s e i n temperature or some other s i m i l a r unfavourable  environmental  changes.  However,  the c a u s a t i v e f a c t o r s i n the formation o f these growth checks have not y e t been determined. As has been s t a t e d before, s c a l e s and o t o l i t h s w i l l be used f o r age determination.  On the s c a l e the f a s t growing zones a r e  represented by wider s c l e r i t e s o r c i r c u l i i and the slow growing zones  78 by narrow sclerites arranged close together in the form of bands or rings.  The literature which deals with temperate f i s h species  describes that these rhythms of growth are seasonal and that there is a close relation between periodic structure of the f i s h hard parts and the growth of the f i s h .  In several instances those hard parts show  the secondary rings or false annuli described above in addition to the normal annual rings. ing  Some doubts have been raised as to the qualify-  characters of an annual and a secondary ring.  This leads to the  some uncertain assumptions in the quality of the causative factors that are responsible for the formation of the growth checks of a f i s h in tropical waters. The classic theory that growth rate is greater during the period of higher temperature is well known.  Cutler (1918) states that  temperature was a controlling factor of s c l e r i t e width in the scale of A higher temperature produce wider sclerites correspond-  Pleuroneotes. ing  to the summer zone and lower temperatures produced narrow sclerites  or the winter zone. Dannevig's (1925) experiments gave the contrary results, that i s , that the s c l e r i t e width was greater at lower temperature and lower feeding.  Dannevig (1925), and Graham (1929) state that there is  a marked correlation between s c l e r i t e width and growth rate caused by an inherent rhythmical response. The narrow zones on the scales and otoliths of cod (Dannevig, 1933)  and the transparent zones in the otoliths of hake (Hickling, 1933)  have been observed to be found during the last part of the summer and autumn in the majority of the specimens; whereas in several other  79 f i s h e s these growth checks are l a i d down d u r i n g the p e r i o d o f lowest temperature.  T h i s c o n t r a d i c t i o n i n the r e l a t i o n o f temperatures to  the formation o f the annual growth checks throws doubt on the p o s s i b l e i n f l u e n c e o f temperature i n the phenomenon o f p e r i o d i c i t y o f the s t r u c t u r e o f the hard p a r t s o f f i s h (Menon, 1950). Gray and Setna (1931) found t h a t Salmo irideus  [S.  gaivdnerii)  which had been f e d c o n t i n u o u s l y throughout the y e a r d i d not show any well d e f i n e d summer and w i n t e r zones Brown (1946) observed t h a t i n specimens kept under c o n t r o l l e d temperature, food, l i g h t , flow o f water, and amount o f l i v i n g space,  composition and a e r a t i o n o f water, the annual  p e r i o d i c i t y i s markedly v i s i b l e on the s c a l e s . Fage and V e i l l e t (1938) suggest t h a t the maturation o f gonads was g e n e r a l l y f o l l o w e d by a decrease i n the growth r a t e . Menon (1950) s p e c u l a t e s t h a t an i n h e r e n t p h y s i o l o g i c a l rhythm i s a more probable c a u s a t i v e f a c t o r i n the formation o f the growth checks. Chidambaram e t a l . (1952) s t a t e t h a t there i s a decrease i n the r a t e o f f e e d i n g and the amount o f food consumed d u r i n g the maturation of gonads.  Food i s an important f a c t o r i n the growth o f a f i s h and  maturation o f gonads i s a momentous p h y s i o l o g i c a l event i n the growth h i s t o r y o f the animal.  The simultaneous occurrence o f reduced f e e d i n g  and gonad maturation may p l a y an e f f e c t i v e p a r t i n the p e r i o d i c formation o f the growth checks." Schneider (1910) suggests t h a t the decrease o f f e e d i n g a t the spawning time, a s s o c i a t e d with the d r a i n on the r e s e r v e s to supply m a t e r i a l to the gonads, i s a heavy output over input o f m a t e r i a l s  ( i n / H i c k l i n g , 1933).  excess of  80 The growth checks s i m i l a r to those found i n temperate f i s h e s have been reported i n the t r o p i c a l f i s h e s by Hornell and Naidu (1924), Devanesan (1943), Nair (1949) and o t h e r s .  However, the v a l i d i t y and  i n t e r p r e t a t i o n o f these checks remains u n c e r t a i n . A d e t a i l e d study o f the l i f e h i s t o r y of the o i l - s a r d i n e (Sardinella  longioeps)  by H o r n e l l and Naidu (1924) gives i n t e r e s t i n g  d e t a i l s on the question o f the age and growth r a t e o f the f i s h .  They  s t u d i e d the growth r a t e by s i z e a n a l y s i s and computed the age by Petersen's method i n a d d i t i o n to s c a l e reading.  T h e i r works lead  s e v e r a l Indian s c i e n t i s t s to determine age and growth o f  Rastrelliger  kanagurta.  Seshappa (1958) s t a t e s that R. kanagurta to 23 cm TL e x h i b i t c l e a r r i n g s on the s c a l e s .  g r e a t e r than o r equal He b e l i e v e s t h a t these  are spawning marks, and thus could be useful i n age s t u d i e s .  Since  t h i s f i s h reaches sexual maturity at 20 cm TL (Chidambaram e t a l . , 1946) or a t 22.4 cm TL (Pradhan, 1956) there i s no reason why the r i n g s only e x i s t a t s i z e 23 cm or above i f the causal f a c t o r i s spawning.  More  s t u d i e s must be conducted to decide whether those r i n g s are useful f o r age determination o f t h i s f i s h .  In g e n e r a l , the absolute age determina-  t i o n o f t r o p i c a l s p e c i e s has not y e t proven to be s u c c e s s f u l . A review o f the l i t e r a t u r e suggests that not enough work has been done on the p h y s i o l o g i c a l f a c t o r s r e s p o n s i b l e f o r the formation o f growth r i n g s . At present, very l i t t l e i s known o f the b a s i c  chemistry  and h i s t o l o g y o f t h i s phenomenon. As has been stated above i t i s not y e t p o s s i b l e to determine the absolute age of t r o p i c a l s p e c i e s , i . e . , Rastrelliger,  using the  81 growth checks.  In s p i t e o f t h e i n a c c u r a c y , the s t a t i s t i c a l method  demonstrated by Petersen (1891) and others  remains the best technique  to o b t a i n the r e l a t i v e o r t h e s t a t i s t i c a l age o f t h i s f i s h .  This  method has been observed t o be s a t i s f a c t o r y f o r f i s h e r i e s work i n v o l v ing lower age c l a s s e s p r o v i d e d there a r e r e l a t i v e l y l a r g e samples. In t h i s study the s t a t i s t i c a l age o f Rastrelliger  was d e t e r -  mined by the modal p r o g r e s s i o n method as d e s c r i b e d by George and Bannerji (1964). By f o l l o w i n g , f o r s e v e r a l seasons, the modal p r o g r e s s i o n o f the average length from t h e time o f f i r s t appearance i n the f i s h e r y , von B e r t a l a n f f y growth parameters can be estimated and the age-length key can be generated. Rastrelliger  1.  kanagurta  e x h i b i t the f o l l o w i n g c h a r a c t e r i s t i c s :  t h e l e n g t h frequency d i s t r i b u t i o n data i n d i c a t e s t h a t a mode o f 14.5 cm appeared i n June and mode o f 14.0 cm appeared i n November ( F i g u r e 16);  2.  the m a t u r i t y stages data show t h a t the l a r g e s t percentage o f s e x u a l l y mature i n d i v i d u a l s was found i n January and May ( F i g u r e 10) ;  these data suggest t h a t the 14.5 cm mode which appeared i n June and the 14.0 cm mode which appeared i n November must r e p r e s e n t the broods t h a t hatched i n about February and June r e s p e c t i v e l y . R. kanagurta  Therefore, the  o f 14.0 - 14.5 cm l e n g t h a r e about 5 months o l d .  82 R.  braahysoma:  1.  the l e n g t h frequency d i s t r i b u t i o n data o f November e x h i b i t modes o f 10, 11, 12, and 16 cm ( F i g u r e 15);  2.  the m a t u r i t y stages data o f March and A p r i l i n d i c a t e mostly s e x u a l l y mature where 100% o f i n d i v i d u a l s were found i n mature gonad c o n d i t i o n s ( F i g u r e 11);  3.  t h i s f i s h always disappears i n May and reappears a t the end o f October and i s never caught during t h i s i n t e r v a l ( i n Tg. S a t a i )  These evidences suggest t h a t the polymodal p o p u l a t i o n was a r e s u l t o f a prolonged spawning season t h a t l a s t s from May t o September.  Therefore,  the s m a l l e s t mode must come from the l a t e s t hatched brood, v i z . , the 10 cm R. braahysoma  has t o be 3 months o l d .  The Von B e r t a l a n f f y growth parameters from both s p e c i e s have been d e s c r i b e d i n the previous s e c t i o n . By employing those parameters and u s i n g t h e age-length formulae d e r i v e d from the Von B e r t a l a n f f y equation as: t  = 1/K ( - I n (1 - l / L ) ) + t t  Q  the age l e n g t h key can be generated (Tables 27 and 28). The r e s u l t s f o r R. kanagurta  i n d i c a t e t h a t the c a l c u l a t e d  lengths have h i g h e r value than the observed modes i n younger groups but are approximately equal i n oTder age groups. a very s l i g h t d i f f e r e n c e e x i s t s .  In R. braahysoma,  however,  83 Age and S i z e Composition E. kanagurta  o f 10 months age c l a s s (21 cm TL) were dominant  i n the 1972 c a t c h (Table 39 j_n Appendices). The f i s h o l d e r than 18 months (23 cm TL) were r a r e l y r e p r e s e n t e d . The range o f the samples was from 4 - 2 4  months o f age (12.5 - 23.5 cm T L ) ; g e n e r a l l y the  commercial catch i s from 6 to 12 months o l d (17.0 - 22.5 cm T L ) . George and B a n n e r j i (1964) s t a t e s t h a t the commerical f i s h e r i e s f o r t h i s f i s h i n India depend mainly on f i s h ranging i n s i z e from 18 22 cm TL, i . e . , the f i s h which are i n the 0-year completing i t s f i r s t y e a r o f l i f e through the f i s h e r y . kanagurta  Manacop (1955) s t a t e s t h a t R.  caught i n the P h i l i p p i n e has an average l e n g t h o f about  25 cm. D r u z h i n i n (1968) recorded the f i s h caught i n Burma waters cons i s t s mainly o f 19.1 - 21.0 cm FL ( o r 21.2 - 23.3 cm TL, c o n v e r t e d ; whereas D r u z h i n i n and Myint (1968) recorded a range o f 15.6 - 22.5 cm FL ( o r 17.3 - 25.0 cm TL, converted) i n t h e i r samples i n the same a r e a , Mergui A r c h . , Burma. In t h i s study E. braahysoma  o f the 9 months age c l a s s (18.5 cm  TL) were dominant i n 1971/1972 c a t c h ; f i s h o l d e r than 18.0 months o f age (22 cm TL) were r a r e l y caught (Table 38 j_n Appendices). The range o f the samples was from 4"- 21 months of age ( 10.0 - 22.5 cm TL ); but g e n e r a l l y the f i s h i n the commercial c a t c h range from 7 to 12 months o l d (17.0 - 20.0 cm T L ) . Hongskul (1972) observed a range o f 10.0 - 23.0 cm TL i n the G u l f o f T h a i l a n d f i s h e r y ; however, the f i s h caught were g e n e r a l l y w i t h i n the 14.0 - 22.0 cm TL range. Manacop (1955) recorded an average  84 TABLE 27 Age-Length-Weight Key o f Age (Month)  Computed Length (cm)  B. kanagurta  from the Java Sea  Observed Mode (cm)  Computed Weight (g)  1  4.93  -  .99  2  8.85  -  6.39  3  11.96  -  16.71  4  14.43  -  30.43  5  16.38  14.5  45.60  6  17.93  16.8  60.87  7  19.16  18.2  75.23  8  20.14  19.3  88.22  9  20.91  20.8  99.45  10  21.53  21.2  109.17  11  22.02  21.6  117.30  12  22.41  22.0  124.07  18  23.52  -  144.77  24  23.79  -  150.15  36  23.88  -  151.97  85 TABLE 28 Age-Length-Weight Key o f R. braohysoma  from Tg. S a t a i  Age (Month)  Computed Length (cm)  1  3.93  _  2  7.19  -  7.56  3  9.89  10.0  18.94  4  12.13  12.0  34.09  5  13.98  13.5  51.31  6  15.52  15.7  69.97  7  16.79  16.3  86.95  8  17.84  17.9  103.55  9  18.71  18.5  118.76  10  19.44  19.5  132.60  11  20.03  20.0  144.53  12  20.53  -  155.16  18  22.15  -  193.10  24  22.67  -  -  36  22.89  -  -  Observed Mode (cm)  Computed Weight (9) 1.33  Figure  15.  Length-Frequency D i s t r i b u t i o n o f R. braohysoma from Tg. S a t a i i n the 1971/1972 f i s h i n g season.  87 H  1  1  1-  H  0ct.71  May.72  Nov\71  Jun.72  2a.  1  1  l-  a.  40  20-  /\  o-  \  •40..Dec,71  Jul.72  20• a. 4 0 - -  Jan.72  Aug.72  20Q.  40Sep.72  Feb.72  20  a.  40Mar. & Apr.72  200  It  Figure  16 16  18  Oct.72  20  $2  tk  —i 1 4  1—-—i  1 1  6  1  8  2  \ 0  2  2  i—i 2  4  TL(  Length-Frequency D i s t r i b u t i o n o f R, kanpgurtn from the north copst o f J P V B i n the 1 9 7 1 - 1 Q 7 2 f i s h i n g sepson.  cm  88 o f about 18.0 cm TL i n the P h i l i p p i n e s waters and D r u z h i n i n (1968) recorded a dominant group o f 18.1 to 21.0 cm FL (20.3 - 23.6 cm TL, converted) i n Burma waters.  In the same l o c a t i o n D r u z h i n i n and Myint  (1968) r e c o r d e d a range o f 16.6 - 22.0 cm FL (18.6 - 24.7 cm TL, conv e r t e d ) i n t h e i r samples. The above data suggest t h a t the Rastrelliger  fisheries in  the I n d o - P a c i f i c Regions a l l i n v o l v e t h e same s i z e range o f f i s h and i t can thus be concluded that these f i s h e r i e s depend on a s i n g l e y e a r c l a s s , i . e . , one y e a r o l d s . Age and S i z e a t F i r s t Capture The age and s i z e a t f i r s t capture o f R. kanagurta o f age (12.5 cm TL) and f o r R. braohysoma  was 4 months  i t was 3 months o l d (10.0 cm  TL) (Figure 15, 16). ' Jones and Rosa (1962) s t a t e t h a t the s m a l l e s t dominant group was 12.0 cm TL f o r R. kanagurta  i n I n d i a ; w h i l e Hongskul (1972) uses  age a t f i r s t capture 4 months as a parameter i n h i s study o f R. p o p u l a t i o n dynamics i n the G u l f o f T h a i l a n d .  braohysoma  No o t h e r r e c o r d o f t h i s  parameter i s a v a i l a b l e i n the I n d o - P a c i f i c Regions. Age and S i z e a t M a t u r i t y The importance o f t h i s parameter i s r e l a t e d to the need f o r adequate spawning s t o c k t o assure a continued supply o f young. d i s c u s s i o n has been conducted on pages 59 and 71.  The  89 Maximum Age and S i z e In t h i s study the maximum length o f R. cm TL (0.52 cm S.E.) and f o r S.E.).  R. braohysoma  kanagurta  was 23.89  i t was 22.92 cm TL (0.76 cm  Both being over 3 years o f age (Table 26, 27, 2 8 ) . Comparison w i t h i n t h e I n d o - P a c i f i c Regions were d e s c r i b e d i n  the previous s e c t i o n . The Length-Weight  Relationship  In f i s h e s the length and weight r e l a t i o n s h i p can be adequately represented by:  W  = aL  b  where b i s an exponent with a value between 2 and 4. I f b = 3.0 i t i n d i c a t e s  isometric  growth, w h i l e b values o t h e r  than 3.0 a r e i n d i c a t i v e o f a l l o m e t r i c growth. The length-weight r e l a t i o n s h i p o f R.  kanagurta  was determined  s e p a r a t e l y f o r males and females, s e x u a l l y mature, immature and u n d i f f e r entiated.  The t o t a l length TL o f samples ranged from 10.0 t o 22.5 cm.  The b values obtained are l i s t e d i n Tables 29 and 30. Comparisons w i t h i n the I n d o - P a c i f i c Regions, i . e . , Indian waters and the G u l f o f T h a i l a n d show t h a t the b values o f t h i s f i s h from the Java Sea area a r e lower. I t i s well known t h a t t h i s c o e f f i c i e n t d i f f e r s between species and a l s o o f t e n d i f f e r between p o p u l a t i o n w i t h i n s p e c i e s . The d i f f e r e n c e s  TABLE 29 The Length-Weight E x p o n e n t i a l (b) Value o f R. kanagurta Identification  B  Variance  from the Java Sea  Male  3.134  0.0068  a (In) -12.15  Female  3.013  0.0072  -11.49  0.0332  Sex U n i d e n t i f i e d  3.175  0.0013  -12.38  0.0332  Sex Immature (mixed)  3.189  0.0062  -12.44  0.1776  Sex U n i d e n t i f i e d  3.175  0.0013  -12.38  0.0332  Sex Mature (mixed)  3.010  0.0037  -11.48  0.1063  Female, M a t u r i t y Stage < I I I  2.933  0.0073  -11.08  0.2084  Female, M a t u r i t y Stage > I I I  3.078  0.0687  -11.82  0.0199  3.193  0.0004  -12.46  0.0106  2.880  0.1266  -10.29  0.3325  A l l Mixed o f R.  kanagurta  A l l Mixed o f R.  braahysoma  Note: * i s 5% l e v e l o f s i g n i f i c a n c e .  Variance (In) 0.1930  ** i s 1% l e v e l o f s i g n i f i c a n c e .  ANC0VA ( t h e S i g n i f i cance o f F Value) F(c.v.) = F(b) = F(a) =* F(c.v.) = F(b) = F(a) = F(c.v.) = F(b) = * F(a) = ** F(c.v.) = F(b) = F(a) = **  ^ o  TABLE 30 The Length-Weight Exponential (b) Values from Various Author i n the Indo P a c i f i c Region o f the Identification R.  kanagurta:  Male Female  Author (Year) Rao, K.V.N., (1962) W a l t a i r , India  R.  kanagurta:  Pradhan, L.B., (1956) Karwar, India  R.  kanagurta:  V a n i c h k u l , P. and V. Hongskul (1963), G u l f of Thailand  Male Female R.  neglectus  Male Female |  b  Variance  3.2628 3.2785  -  .004983 .004874  3.1737  -  .005978  3.7633  -  -6.7081 (log) -5.0244 (log)  -  -  -5.2417 (log) -5.1819 (log) -6.0421  -  5.5390 (log)  -  3.0375 V a n i c h k u l , P. and V. Hongskul (1963), G u l f of Thailand  Rastreliger  3.1463 3.1235  R.  braohysoma  Jones and S i l a s (1962) Andaman I s . , India  3.5779  -  R.  kanagurta  Jones and S i l a s (1962) Andaman I s . , India  3.3087  -  a  Variance  -  -  vo  92 may be due to sex, maturity and season.  Vaznetsov (1953) s t a t e s that  during development f i s h pass through s e v e r a l stanzas, each of which may have i t s own the  b value.  Tesch (1968) s t a t e s that w i t h i n any stanza  b value w i l l o f t e n be nearly constant throughout the year or  throughout a s e r i e s of d i f f e r e n t environments, whereas the  a_  value  w i l l vary s e a s o n a l l y , and between h a b i t a t s . The a n a l y s i s o f covariance i n d i c a t e s that b d i f f e r s s i g n i f i c a n t l y ( 5 % ) , i n R. kanagurta,  between s e x u a l l y - u n i d e n t i f i e d and sex-  u a l l y - i d e n t i f i e d (mixed) specimens (Table 29). of b values due to sex or sexual maturity The c o e f f i c i e n t due to the above evidences  There i s no d i f f e r e n c e  stages.  a_, by c o n t r a s t , show s i g n i f i c a n t d i f f e r e n c e s (Table 29).  These two c o n d i t i o n s suggest that the f i s h e x h i b i t s at l e a s t two stanzas during i t s l i f e ; the f i r s t i s while i t i s young and s e x u a l l y undifferentiated.  The second stanza begins as soon as i t s sex can be  i d e n t i f i e d which i s probably a few months before i t reaches  maturity.  In many s p e c i e s s e v e r a l stanzas are completed during embryonic and l a r v a l l i f e ,  and a l l subsequent growth comprises a s i n g l e stanza  (Tesch, 1968). Hecht (1916) s t a t e s that i n f i s h the body form i s l a i d down very e a r l y i n l i f e and i s maintained w i t h i n narrow l i m i t s throughout the period of growth, and thus has uniform but indeterminate  growth.  Ssentongo (1971) says that t h i s kind of growth a p p l i e s o n l y to external surfaces  f o r K e l l i c o t (1908) shows that  i n a dog f i s h  the b r a i n  and v i s c e r a d i f f e r  i n t h e i r growth rates i n much the same way as i n  higher v e r t e b r a t e s .  To obey H e c h t s law Ssentongo s t a t e s that the 1  b  93 value should be w i t h i n a 2.5 - 3.5 l i m i t , otherwise the b value cannot apply over a wide range o f l e n g t h without causing profound changes i n body form.  Furthermore, he suspects t h a t these values came from b i a s e d  samples. Recrui tment Recruitment i s g e n e r a l l y d e f i n e d as the number o f f i s h of a s i n g l e y e a r group e n t e r i n g the e x p l o i t a b l e phase o f a s t o c k , o r , as the number o f f i s h o f a s i n g l e y e a r group a r r i v i n g on a f i s h i n g grounds. I t i s important i n f i s h e r i e s management as an index o f abundance t h a t i s used f o r p r e d i c t i o n , and has been d i s c u s s e d i n d e t a i l by R i c k e r (1954 , 1958), others.'  Beverton and H o l t (1957), Gushing (1973), and  1  Recruitment i n Rastrelliger  has not y e t been s t u d i e d . Whether  i t occurs e a r l y o r l a t e i n l i f e i s determined by the r e l a t i v e p r o x i m i t y of the nursery grounds to the f i s h i n g grounds. yet understood.  T h i s r e l a t i o n s h i p i s not  However, to determine the age a t r e c r u i t m e n t ( t ) the r  most d i r e c t i n f o r m a t i o n a v a i l a b l e i s t h a t obtained from l a n d i n g samples.  The estimated t w i l l not be h i g h e r than the t r u e v a l u e ,  s i n c e r e j e c t i o n o f the s m a l l e s t f i s h w i l l not o c c u r .  T h i s i s caused  by the nature o f the market and f i s h e r i e s systems i n the a r e a , where n e i t h e r mesh s i z e nor l e g a l f i s h s i z e r e g u l a t i o n s e x i s t , and a l l s i z e s of f i s h are marketable. The data suggest t h a t the t f o r R. braahysoma of age (10.0 cm TL) and f o r R. kanagurta (12.5 cm TL)  ( F i g u r e 15, 16).  was 3.0 months  was 4.0 months o f age  94  The change in recruitment seems to exert more influence than does fishing pressure on stock fluctuations of Rastrelliger  as this  fishery depends on a single 0-year class. The stock recruitment relationship which is necessary to relate the abundance of pre-recruit phase to age class strength is not yet established.  Therefore, the increase in fishing intensity  should be conducted cautiously.  Survival Rates The method of a single catch curve analysis as described by Robson and Chapman (1961) was employed (Figures 17 and 18; Table 31 and 32).  This method has been shown by B a y l i f f (1966) to be better  in estimating this parameter than other methods. The survival rates of R. kanagurta  for three different fishing  seasons were calculated in monthly periods. In West Monsoon 1971 the survival rate was 0.3348 (variance = 0.0010); in the East Monsoon 1972 was 0.7154 (variance = 0.0020), and in the West Monsoon 1972 was 0.3540 (variance = 0.0020).  A marked  difference between the survival rates in the West and East Monsoon suggests that they are two different populations, which again supports Hardenberg's hypothesis (1938). Assuming that the fishing and natural mortalities are constant, then there was an increase in the recruitment of 5.47% in the 1972 West Monsoon's population. The survival rate of R. braahysoma  from Tg. Satai in 1972  fishing season was 0.4411 (variance = 0.0002). Hongskul (1972 reported that the average of the instantaneous  95 TABLE 31 E s t i m a t i o n o f S u r v i v a l Rates o f R. kanagurta i n the Java Sea by the Method o f Robson and Chapman (1961) 1. November 1971 Age-Month  Frequency  7  Coded Age  Calculation  -  -  T = 10+2(7)+3(2) = 30 n = 41+10+7+2 = 60 m = 2  9  18  -  s = n-m+T - 60-2+30= 0 34  10  41  0  11  10  I  12  7  II  18+  2  III  .  8  T  30  5  v a r i a n c e = ^" ^ = 0.0026 n(l-s ) s  s  3  2. December 1971 Age-Month  Frequency  7  Coded Age -  8  18  9  36  -  10  51  0  11  14  I  12  5  II  18+  2  III  Calculation T n m „  = 14+2(5)+3(2) = 30 = 51+14+5+2 = 72 = 2 _ 30 _ ~ 72-2+30 n  n  v a r i a n c e = • ^ " ^ = 0.0021 72(1-.30^) 3 0  , 3  2  96 TABLE 32 E s t i m a t i o n o f S u r v i v a l Rate o f R. braohysoma  Age (Month)  Frequency  Coded Age  i n Tg. S a t a i Area (1972)  Calculation  9  450  0  T = 786  10  327  I  n  11  206  II  12  13  III  18+  2  IV  0.8185 0.5589  = 998  m = 2 s =  0.44  v a r i a n c e = 0.0002  1  I K  Figure  1  5  1  1  1  1  1  1  1  6  7  8  9  10  11  12  1  H  1  1  16  18  1  AGE  17. C a t c h c u r v e s f o r R. k a n a g u r t a o f t h e n o r t h c o a s t o f J a v a , A. West Monsoon 1971; B. E a s t Monsoon 1972: C. West Monsoon 1972. A b s c i s s a age l n months; o r d i n a t e - l o g a r i t h m o f t h e %frequency.  98  l n %f 3f  2+  It  01  -14-  k  5  6 7  8  9  10  11  12  14  16  18 AGE  F i g u r e . 18. C a t c h curve f o r R. brachysoma o f Tg. S a t a i i n 1971-1972 f i s h i n g season. A b s c i s s a - age i n months; o r d i n a t e - l o g a r i t h m o f the % frequency.  t o t a l m o r t a l i t y (Z) d u r i n g 1962-1968 o f R. braohysoma  99 i n the G u l f of  T h a i l a n d v a r i e d between 0.7028 - 1.3470, with an average value o f 1.0124 along the western c o a s t and the inner G u l f ) . Assuming the n a t u r a l m o r t a l i t y r a t e s o f t h i s s p e c i e s i s equal then the lower instantaneous m o r t a l i t y (Z = 0.8185) i n the Tg. S a t a i area i s probably due to a much lower f i s h i n g pressure as compared with the G u l f o f T h a i l a n d . Mortalities There are a number o f approaches t h a t can be taken to estimate m o r t a l i t y o f e x p l o i t e d f i s h populations.. Tagging o f f i s h and subsequent recaptures i s the best f i e l d technique t h a t can be employed i n the c a l c u l a t i o n o f m o r t a l i t i e s and other p o p u l a t i o n  parameters.  Monitoring o f the c a t c h and f i s h i n g e f f o r t i s another u s e f u l technique s i n c e catch per u n i t o f e f f o r t i s approximately  proportionate  to stock abundance. Total m o r t a l i t y can a l s o be i n f e r r e d from the age o f the c a t c h .  compositions  T h i s approach was employed i n t h i s study by u t i l i z i n g  the method d e s c r i b e d by Robson and Chapman (1961). The s e p a r a t i o n o f t o t a l m o r t a l i t y i n t o i t s components, nature and f i s h i n g m o r t a l i t i e s , i s d i f f i c u l t i f f i s h i n g represents only a small f r a c t i o n o f the t o t a l m o r t a l i t y (Cushing, 1968). Assuming t h a t n a t u r a l m o r t a l i t y o f R. kanagurta  i s constant  throughout the y e a r , Gull and's (1969) method can be used to estimate these parameters  (Table 33).  He s t a t e s t h a t i f the amount o f f i s h i n g  100 TABLE 33 Estimates o f M o r t a l i t i e s o f R. kanagurta November 1971 s  =  by the Method o f Gulland (1969) December 1971  0.34  = 0.30  i = 1.0789 ( o r Z)  = 1.2040  f  = 6,923  = 5,853 ( t o t a l e f f o r t )  Gulland's equation  Z = q f  1.0789 = q x 5,853 + M then:  +  M 1.2040 = q x 6,923 + M  q = 0 00012 M = 0 37 ( n a t u r a l m o r t a l i t y )  f i s h i n g m o r t a l i t y = 0.70  f i s h i n g m o r t a l i t y = 0.83  101 changes t h i s w i l l r e s u l t i n a change i n t o t a l m o r t a l i t y . He shows t h a t p l o t t i n g estimated t o t a l m o r t a l i t y Z a g a i n s t f i s h i n g e f f o r t ( f ) values y i e l d s a s t r a i g h t l i n e with a slope q(= the c o e f f i c i e n t o f c a t c h a b i l i t y ) , and an i n t e r c e p t M on the y - a x i s . The e s t i m a t e d  survival rate of  R. kanagurta  i n November 1971  was 0.34 (rounded value; v a r i a n c e = 0.0026) gives an instantaneous t o t a l m o r t a l i t y Z o f 1.08.  In December 1971 i t was 0.30 (rounded v a l u e ;  v a r i a n c e = 0.0021) with a corresponding Z o f 1.20. The t o t a l e f f o r t f (= t o t a l catch d i v i d e d by catch per u n i t o f e f f o r t ) were 5,853 and 6,923 u n i t e f f o r t s f o r November 1971  and  December 1971 r e s p e c t i v e l y (Table 41 i n Appendices). By employing Gull and's method d e s c r i b e d above, those data o f R. kanagurta  give an estimate o f q = 0.00012, F = 0.70 i n November 1971  and F = 0.83 i n December 1971, and an instantaneous n a t u r a l m o r t a l i t y M of  0.37. The n a t u r a l m o r t a l i t y and growth r a t i o (M/K) o f  o f the Java Sea then was 1.6. ratio for  R. kanagurta  R. kanagurta  Bannerji (1970) suggests t h a t t h i s  p o p u l a t i o n i n the eastern coast o f India ranged  from 1.5 to 2.5 (with various values o f K and an estimated value o f M = 0.65).  The M/K value o f t h i s f i s h from the Java Sea compared  f a v o u r a b l y with the M/K values obtained by Bannerji i n Indian waters. Hongskul (1972) estimates the M/K r a t i o f o r the G u l f o f T h a i l a n d to be 2.0.  I f the  R. braohysoma  R. braohysoma  in  p o p u l a t i o n from  Tg. S a t a i has the same M/K value as i n the Gulf o f T h a i l a n d , the n a t u r a l m o r t a l i t y M and f i s h i n g m o r t a l i t y F values w i l l be 0.38 and r e s p e c t i v e l y (K was 0.19; and Z was 0.82).  0.44  102 These estimated parameters w i l l be used l a t e r i n p o p u l a t i o n dynamics s t u d i e s . Dynamics o f P o p u l a t i o n s The r e s u l t s obtained as mentioned i n the previous s e c t i o n s i n d i c a t e the c h a r a c t e r i s t i c s o f the Rastrelliger  p o p u l a t i o n s i n the  Java Sea. They possess high values o f growth and n a t u r a l m o r t a l i t y r a t e s . The stock r e c r u i t m e n t r e l a t i o n s h i p cannot be determined i n t h i s study, thus o n l y the y i e l d p e r r e c r u i t model has been used.  The model i s  based on the assumption t h a t c a t c h obtained from a y e a r c l a s s throughout i t s f i s h a b l e l i f e span i s p r o p o r t i o n a l t o i t s i n i t i a l numbers when r e c r u i t e d . Beverton and H o l t Y i e l d Model Beverton and H o l t (1957) have d e r i v e d a y i e l d model t h a t i s very useful f o r e v a l u a t i n g the p o t e n t i a l y i e l d o f a f i s h e r y . T h e i r equation i s :  e-^W  Y/R = FW  3  ;  -nK(t -t ) c  0  Z  n=0  (1-e ,-(F+M+nK)(t -t ) x  F+M+nK  The b a s i c assumption i s t h a t growth i s i s o m e t r i c . Y  y i e l d i n weight,  R  number o f r e c r u i t s e n t e r i n g the f i s h e r y a t age t  Woo  maximum weight o f an i n d i v i d u a l f i s h , h y p o t h e t i c a l age o f zero l e n g t h , o r t p i s age a t time o f r e c r u i t m e n t , o r t , i s age a t f i r s t capture, p  age o f e x i t from the f i s h e r y ,  c  103 K  the Von B e r t a l a n f f y growth parameter,  U  i s 1,-3, 3, and -1 f o r n = 0, 1,2,  and 3 r e s p e c t i v e l y .  I t i s well accepted that the growth o f many f i s h i s not isometric.  For such growth the c a l c u l a t i o n o f y i e l d can be conducted  by using the Incomplete Beta Function t h a t was d e s c r i b e d by Jones (1957) and the equation was expressed  by Wilimovsky and Wicklund (1963) as:  Y = F/K R W e ^ " ^ ) { [x, P, Q]-[X P, Q] } 2  r  where:  Z X  instantaneous ~K(t -t )  Xi  e  P Q  Z/K 1 + b;  e  c  total mortality,  0  -K(t-t ) 0  b i s the length-weight  exponent.  Wilimovsky and Wicklund (1963) prepared a t a b l e f o r t h i s f u n c t i o n . Employing the Beverton and H o l t (1957) model, the y i e l d s were c a l c u l a t e d and i s o p l e t h diagrams were constructed (Figures 19, 20, 21, 22 and 24). R.  kanagurta:  to  =  t  = 4.0  months,  t  = 4.0  months,  t  = 18.7  months,  K  = 0.2316  W  = 152.0 grams  n  r  m  0.92 months,  104 R.  braohysoma:  t  Q  = 0.10 months  tr  = 3.0 months  t  = 3.0 months  t  = 21.3 months  K  = 0.1887 = 213.0 grams.  The model was simulated with v a r i o u s parameter v a l u e s , the f i s h i n g m o r t a l i t y F ranged from 0.1 to 1.5 with 0.1 increments; the natural m o r t a l i t y M ranged from 0.1 t o 1.0 with 0.1 increments; and t from 4.0 months f o r R. kanagurta  and 3.0 months f o r R. braohysoma  to  12.0 months with one month increments. D e t a i l e d d i s c u s s i o n on the concept o f y i e l d models have been given by Beverton and H o l t (1957), R i c k e r (1958), Schaefer and Beverton (1963), Gulland (1969), and o t h e r s . In an e x p l o i t e d f i s h p o p u l a t i o n the f i s h a r e r e c r u i t e d to the f i s h e r y a t age t but a r e not caught u n t i l the age a t f i r s t c a p t u r e , t .  In Rastrelliger  f i s h e r i e s i n the Java Sea, where t h e r e i s no  f i s h i n g r e g u l a t i o n such as l e g a l mesh o r f i s h s i z e , the t i s equal to t .  T h i s c o n d i t i o n o f the f i s h e r y i s named a "knife-edge" f i s h e r y . Observation on y i e l d o f R. kanagurta  as r e v e a l e d by the  i s o p l e t h diagrams a r e given below ( F i g u r e s 19, 20 and 21). The g r e a t e s t y i e l d o f R. kanagurta  can be o b t a i n e d i f the  s i z e o f f i r s t capture i s 15.5 cm TL with a f i s h i n g m o r t a l i t y o f 1.4  105 (the natural m o r t a l i t y was 0.4).  The y i e l d i n weight per r e c r u i t i n  t h i s c o n d i t i o n i s 22.4 g; and a t present where the f i s h i n g m o r t a l i t y i s 0.8, the y i e l d i n weight per r e c r u i t i s 21.5 g. The age a t f i r s t capture a t present i s 4.0 months (with F = 0.8) and the y i e l d per r e c r u i t i s 21.3 g.  The f i s h i n g i n t e n s i t y can  be increased without a f f e c t i n g the f i s h e r y u n t i l the maximum y i e l d per r e c r u i t i s reached a t a f i s h i n g m o r t a l i t y o f 1.3.  T h i s means that a t  maximum f i s h i n g pressure, the i n c r e a s e o f 62.5% f i s h i n g m o r t a l i t y w i l l cause the y i e l d per r e c r u i t t o increase by 1.6%. A g r e a t e r i n c r e a s e o f f i s h i n g m o r t a l i t y o r f i s h i n g pressure o f 75% t h a t gives a y i e l d per r e c r u i t increase o f 4.2% can be achieved i f the f i s h e r y s t a r t e d to catch the f i s h a t 15.5 cm TL ( o r 4.5 months o f a g e ) . An estimated natural m o r t a l i t y o f 0.38 and f i s h i n g m o r t a l i t y of 0.44 (see the previous s e c t i o n ) were employed i n c o n s t r u c t i n g the i s o p l e t h diagram o f R.. braahysoma  o f Tg. S a t a i (Figures 22, 23 and 24).  Under the present c o n d i t i o n where the f i s h i n g m o r t a l i t y i s 0.44, the natural m o r t a l i t y i s 0.38 and the s i z e a t f i r s t capture i s 10.0 cm TL, the y i e l d i n weight per r e c r u i t i s 18.0 g. The h i g h e s t y i e l d per r e c r u i t o f 20.8 g can be obtained i f the length o f f i r s t capture i s 12.0 cm TL and the f i s h i n g m o r t a l i t y i s 1.5. The f i s h i n g pressure can be doubled without harming the stock s i n c e R. braahysoma  has an asymptotic y i e l d per r e c r u i t to f i s h i n g  m o r t a l i t y r e l a t i o n s h i p diagram f o r n a t u r a l m o r t a l i t y greater than 0.4. Under t h i s c o n d i t i o n the y i e l d per r e c r u i t w i l l gain an i n c r e a s e o f only 15.6%.  106  1  I  .1  .2  Figure  1  .3  1  .4  1  .5  1  1  >  .6  .7  .8  1  .91.0  1—  1  1  1  1  .1  .2  .3  .4  )——  .5  F  19. Y i e l d i s o p l e t h diagram of R. kanagurta. Y i e l d i n weight per r e c r u i t (Y /R) was a t an i n t e r v a l s o f 2 grams; natural m o r t a l i t y (M) was 0.4, t = 4.0 months. The f i s h i n g m o r t a l i t y F = 0.8 was i n 1971. w  c  1 -  1  Figure  *  2  «  3  '«5  1 .6  1 .7  1 .8  1 .9  1 1.0'  1  1  .1  .2  —| .3  1.4  .5  F  20. Y i e l d per r e c r u i t as a f u n c t i o n o f f i s h i n g m o r t a l i t y o f R. kanagurta. The natural m o r t a l i t y M range from 0.05 to 1.0; t = t = 4.0 months. The f i s h i n g m o r t a l i t y F = 0.8 was i n 1971. c  r  Figure  21. Y i e l d per r e c r u i t as a f u n c t i o n o f f i s h i n g m o r t a l i t y of R. kanagurta; the natural m o r t a l i t y (M) range from 0 . 0 5 - 1 . 0 : t=45 and t = 4.0 months. c  109  I  1  1  1  1  .2 .3  .4  Figure  1  .5  1  1  .6  .7  :  i  .8  1  .9  1  1  1  1  1  1  1.0 .1  .2  .3  .4  .5  22. Yield isopleth diagram of E. bvachysoma. recruit (Y /R) at an interval w  -I  F  Yield in weight per  of 1.0 gram.  i t y (M) = 0.4 and the age at f i r s t capture t  The natural mortal = 3.0 months.  Figure  23. Y i e l d per r e c r u i t as a f u n c t i o n o f f i s h i n g m o r t a l i t y (F) o f R„. braahysoma from Tg. S a t a i ; with t = 3.0 and t = 3.0 months, the natural m o r t a l i t y (M) ranged from 0.1 t o 1.0:  Figure  24. Y i e l d per r e c r u i t as a f u n c t i o n of f i s h i n g m o r t a l i t y of R. braahysoma. The natural m o r t a l i t y M range from 0.1 to 1.0; t = 4.0 and t = 3.0 months.  112  As has been s t a t e d above, the h i g h e s t y i e l d per r e c r u i t i n c r e a s e can be obtained by i n c r e a s i n g the s i z e at f i r s t capture from 1 0 . 0 cm to 1 2 . 0 cm TL. were drawn from the (Hongskul,  1972),  However, s i n c e the e s t i m a t i o n o f parameters  H. braahysoma  s i t u a t i o n i n the G u l f o f T h a i l a n d  these p r e d i c t i o n s need v e r i f i c a t i o n with o r i g i n a l  data from these areas. The Incomplete Beta Function gives unbiased y i e l d estimates f o r f i s h with a l l o m e t r i c growth.  I t was d e s c r i b e d by Jones  an equation was generated by Wilimovsky and Wick!und  (1963)  (1957)  and  from the  Beverton and H o l t Y i e l d equation. The d i f f e r e n c e s i n y i e l d a b s o l u t e values obtained are caused p a r t l y by l o g transformations and probably the rounded f i g u r e o f the instantaneous t o t a l m o r t a l i t y Z.  However, the a b s o l u t e y i e l d value  i s not o f primary importance i n t h i s study but i t responded to the changes o f parameters.  R i c k e r Y i e l d Model Ricker  (1958)  growth r e l a t i o n s h i p .  g i v e s a y i e l d model which i s based on an e m p i r i c a l I t permits s i m u l a t i o n o f growth and m o r t a l -  i t i e s when they cannot be expressed i n a s i n g l e f u n c t i o n o f time. This model i s probably the best y i e l d  model  a v a i l a b l e t h a t can be  a p p l i e d t o t r o p i c a l s p e c i e s which possess a s h o r t l i f e span, seasonal growth, and v a r i a b l e f i s h i n g i n t e n s i t y over a f i s h i n g season.  This  113 has been demonstrated by B a y l i f f (1966) f o r anchovieta,  Cetengvaulis  mysticetus, i n the G u l f o f Panama.  The equation i s :  (  P T * W 1  +  e T 9  "  1  T)  i T=T  R R  where: Y£  e q u i l i b r i u m y i e l d under given c o n d i t i o n s ,  g  instantaneous  rate o f growth,  i  instantaneous  rate o f total mortality,  p  instantaneous  rate o f fishing mortality,  q  instantaneous  r a t e o f natural m o r t a l i t y ,  T  time i n t e r v a l (months),  T^  the f i r s t p e r i o d under c o n s i d e r a t i o n ,  T  the l a s t p e r i o d under c o n s i d e r a t i o n ,  W  weight o f an i n d i v i d u a l f i s h during t h a t p e r i o d .  The assumption o f the model are: 1.  growth and m o r t a l i t y r a t e are independent o f population size;  2. c a t c h a b i l i t y i s constant throughout f i s h i n g season; 3.  the population i s s t a b l e . A computer program by Wilimovsky (1972) was used. The r e s u l t s  appear on Tables 24, 35 and 36.  114 The t o t a l e q u i l i b r i u m y i e l d o f R. kanagurta  f o r an i n s t a n t a n -  eous f i s h i n g m o r t a l i t y o f 0.8 and natural m o r t a l i t y o f 0.42 was 1.35 g per gram r e c r u i t . The f i s h i n g m o r t a l i t y 0.0 f o r age c l a s s e s 11, 12, 13, and 14 months o l d i s r e l a t e d t o u n a v a i l a b i l i t y o f these groups as they were l e a v i n g the f i s h i n g ground i n the East Monsoon ( f o r West Monsoon population) and were being r e p l a c e d by another new stock t h a t enter the f i s h i n g ground. This s i t u a t i o n l i k e l y serves as a " n a t u r a l " c l o s e d f i s h i n g season f o r the f i s h e r y , which w i l l strengthen the incoming stock on the f i s h i n g ground. The same s i t u a t i o n occurs with R. braahysoma  i n Tg. S a t a i  area where the f i s h a r e u n a v a i l a b l e during the months o f May to October.  The t o t a l e q u i l i b r i u m y i e l d f o r a f i s h i n g m o r t a l i t y o f 0.48  and a natural m o r t a l i t y o f 0.34 was 1.96 g per gram r e c r u i t .  I f the  f i s h i n g i s doubled, the y i e l d w i l l increase t o 2.98 g per gram r e c r u i t with a decrease i n the mode length o f the biomass f r o m 21.3 cm TL t o 20.9 cm TL. The i n c r e a s e i n f i s h i n g pressure tends to decrease the mean s i z e (length) o f the biomass.  Y T F l r> V Q D F L  AGE 4,00  MEAN LENGTH 144.  MEAN WEIGHT  —  5.00  164.  0.  6.C0  179.  0.  7.CO  192.  0.  6.00  2C1 .  0.  209 .  0.  10.00  21 = .  0.  , 11.CC  22C.  c.  12.00  224.  0.  13.00  227.  c.  14.00.  2 30.  0.  15.CC  232.  c.  16.00  233 .  0.  17.00  234.  0.  13.00  233 •  0.  9.00  !  i  1 ir—-—  1 i  TOTAL  TABLE  0  AR 1 Tr-iVFT I C r.SA.'i  P  G-P-Q  WEIGHT CHANGE  C.29S  1.347  STOCK  MEAN BICMASS  YIELD  1C00.  C.  V  >  G  =  0. 40  0.0 3  0.C60  0.23  0.03  0.030  C.174  1.190  0.21  0.03  0.030  0.103  1.114  0.15  0.02  0.0 = 0  0.042  1.04 3  0. 11  0.C3  o.oeo  0.2 09  0. 09  0.03  o.oeo  -0.016  0.953  0.07  0.02  0.000  0.041  1.0-2  0.05  0.03  coco  0.C26  0. C4  0.02  O.CCO  0.012  1.012  0. 04  0.03  0.000  0.010  1.010  0.0 2  0.0 3  0.030  -C.032  0.920  so ~ o.cso  -0.C96  0.903  -0.093  0 . 9 1C  -0.096  0.903  0.01 ~0"f03~  1347.  ~67b  0. O i  0.02  0.01  0.03  0.020  1.56  0.42  0.50  1173.  93.  1475.  lis.  1696.  135 .  1S26.  .146.  1374.' "  149.  1567 .  149.  1604, 1737. ISo:.. 1.009 16S2. 1852. 1B91.  0.  1936.  0.  1994.  0.  2017."  0.  1921. ' 1.026 19S2. 2C07. 2023.  0.343  1947.  155 .  1732.  14 2.  1620.  129.  1473.  117.  1S67. 1696. 1544. 1402. TOTAL YIELD =  1245.  34 Instantaneous r a t e s o f growth (q). natural m o r t a l i t y "(a) and f i s h i n a m o r t a l i t y (p) f o r R. kanagurta o f the Java Sea. The f i s h i n g and n a t u r a l m o r t a l i t y i s d i v i d e d evenly through the y e a r , except during the months which where i t migrates Trom the Java Sea and, t h e r e f o r e , u n a v a i l a b l e to the fishermen, g - p - q i s equal t o g - i . Instantaneous r a t e s of growth (g) d i s t r i b u t e d according to t h e i r observed seasonal "Incidence. The computdliun uT e q u i l i b r i u m y i e l d , i n successive, ribhiny seasons, from 1 ,000 w e i g h t - u n i t s at age 4.0 months. :  i  YIrL!)  r AGE  MEAN  M E A.N  LENGTH  WEIoHT  121.  5.30  139.  0.040  16S.  0.  S.00  17S.  0.  9.00  1 S 7.  +i vn • w.-\ vr\  1 94 .  c. c.  11 . C C  2 00.  0.  12.00  2C5 .  o..  13.00'.  209.  0.  14.CO  213.  0.  16.00  213.  0.  17.00 .  2 20.  It .00  222 .  0.  19.CC  223.  0.  20.30  224.  0.  1343 .  5 3 .  0.02  0.040  1.394  0.332  2023.  30.  0.02  0 . 040  0.257  1.293  2702 .  ICS . •  0.02  0.040  0 . .6 3  1.13 3  3323 .  133.  3823.  152 .  4201.  163 .  3607. 0.02  0  4  C' 0 L  0.112  1.119 4039.  0.13  0.02  C. i l  0.02  COS  0.02  0.07  0.02  0.040  c.coo coco  0.000  l.OSC  0.077  43 6 3. 1.094  0 •09 C  4569 .  C.  493= .  0.  5234.  0.  54 6 9 .  0.  5652 •  c.  5673 .  227 .  ; pi J .  221  5 347 .  213 .  5 169 .  206.  496;  i i c i  4775. 1.06c  . C.06 6  5101. 0.C51  1.052 5363.  0.05  .0.02 0.02  coco 0. 000  n <J * s, J ^  1.C37  C.32 9.  1.029  5570. 5734.  0.C4 3.  YIELD  r'.AS S  30<-9.  0. 04  216.  MEA.^I  61C  2 3 5 6.  0.17  15.00  STOCK  1.690  0.525  0.  7.0 0  0.02  0.040  0.9S0  -0.019  -  5622. 0 . 02  0.02  0.040  "0 •  03  C. 967  2  5437. 0. 02  0.02  C.04_0  0.966  - 0 .03 3  5257. 0 . 02  TOTAL  0.02  0.  0 . 22  ... —  oHT  1690.  0.31  1  A'E I  0. -  C  C - K - Q  3 I Tr> r T T T " F A N  1000.  0.39  ". Z  P  A  CnAMGE  0.53 4.00  0  •on"!.  0.  99.  3.00  r•  G  ?  0.02  C966  -0.033  .  5 03 2. 0 • Z x  0.02  0. 0 1  0.C2  C.0',0  0.954  -0.04 7  .  4545 . C.C40  -0.047  •  4737 .  C.953  139.  4625. 2 . 36  0 . 34  C.4S  1.540  •  TOTAL  YIELD  =  1962 .  TABLE 35. Instantaneous r a t e s ' o f growth ( g ) , natural m o r t a l i t y (q) and f i s h i n g m o r t a l i t y (p) f o r R. brachysoma from Tg. S a t a i area. As i n TABLE 34, except that the computation of e q u i l i b r i u m y i e l d from 1 ,000 w e i g h t - u n i t s a l aye 3.0 inuriLlis. ; :  —  sir*-*  ———. r  ,  AGE  MEAN LENGTH  1  3 .CO  t  1  iI i 1  i  !  99.  MEAN WEIGHT  121.  0.  5. CC  139.  0.  6. CO  155.  0.  7.00  168.  0.  S .00  173.  C.  9.CO  137.  0.  • 10.00 •  194.  0.  11. C C  2 CC .  o. •  1 2 .CO  2C5 .  0.  13.CO' •  209.  0.  14.00  213.  0.  15.00  216 .  0.  16 •GC  218.  0. .  17.CO  220.  0.  15.00  222 .  0.  19.00  223.  0.  20. CO  224.  0.  TOTAL  TABLE  0  p  G-P-Q  WEIGHT CHANGE  STOCK,  0.  4. CO  : :  G  Yf-i n  0.58 0.39 0.31 0. 22  0.02 0.02  0.07 0.05  1.624  0.292  1.339  0.C3O  0.217  1.242  0.02  0.030  0.12S  1.136  0.072  1.075  0. 13 0.02  0.0 3  0. C 8 0  0.4i-5  0.02  0. 17 0.02  0.11  0. C30  C.C2 0.02 CO 2  0.02  0. 030 0. 0 3 0 0. GOO 0. CCO O.OOO  0.027 0.090 0.066 0.051  0.029  1.029  0.02  0.02  -0.059  C C30  _ ^  ~- ~i  — w .U /  0. C2 0.02  0.02 _C_C80 __^0 C7 3 JL  0.02  0 . C 5 0 -0.07 2  0.01 . C.C-2 0. 030 0.01 2. 36  i Z  0.02 . 0.030 0. 34  0.96  -0.037 -0.03 7 1.060  2704. 3074. 3307. 3432. 3756. 4 012.  1.C52  0.04 _ _ C _ 0 2 _ _0.COO  o.oac  2175.  1.06 3  1.037  0.02  1624.  1.C94  0. C 2 6  0. 04  1000.  1.037  0. OCC  4222. 4331. 4511.  0.942  42^9.  0.929  3943 .  0.92  2665.  0• v2S 0.916 0.916  MEAN BIC.v.ASS  3406. . 3122. 2662. '  YIELO •  1512.  104.  1399.  1T  2439.  195.  2 5 59.  23i.  3190.  25 5 .  3269 .  269 .  3 594.  °»  33S4.  0.  4il7.  0.  4302.  0•  4446 .  0.  433C.  350.  4099 .  327.  3 303.  20^- .  3537.  232 .  i •  261. 2 992.  TOTAL YIELD =  239. 29S3.  36. Instantaneous r a t e n f g r o w t h ( g ) , n a t u r a l m n r t a l i t y (q) anH f i c h j n g m o r t a l i t y (p) of R. braohysoma from Tg. S a t a i a r e a , as i n TABLE 35, except t h a the f i s h i n g m o r t a l i t y (p) was doubled. ~ ; " :  118 IV. >*  GENERAL DISCUSSION  The genus Rastvelligev  has been accepted s i n c e the time Jordan  proposed i t (Jordan and S t a r k s , 1908). There are two species w i t h i n the genus that have caused controversy, namely Rastvelligev Bleeker (1851) and  R. neglectus  van Kampen (1907).  bvachysoma  Some recognize them  as two v a l i d s p e c i e s and others t h i n k t h a t R. neglectus the former s p e c i e s .  i s a synonym of  T h i s problem probably e x i s t s because past systema-  t i c s t u d i e s of marine f i s h e s i n v o l v e d too few specimens and were l e s s a n a l y t i c a l than the systematic s t u d i e s of f r e s h water f i s h e s (Hubbs, 1943). Natural populations are almost always d i s t i n g u i s h a b l e by d i f f e r e n c e s i n t h e i r morphology. The general method used to i d e n t i f y populations at any rank i s by determining the d i f f e r e n c e s of t h e i r morphological  characters.  These characters can be d i v i d e d i n t o two  kinds, q u a l i t a t i v e and q u a n t i t a t i v e c h a r a c t e r s .  Any of the l a t t e r can  be expressed e i t h e r as a count ( m e r i s t i c character) or as a measurement (morphometric c h a r a c t e r ) . Two c l o s e l y r e l a t e d species u s u a l l y d i f f e r i n s e v e r a l characters.  Sometimes the d i f f e r e n c e s between them are not pronounced,  thus the characters employed should be those t h a t e x h i b i t the g r e a t e s t divergence.  The degree of d i f f e r e n t i a t i o n i s d i f f i c u l t to  determine,  e s p e c i a l l y from small samples, but, as Hubbs (1943) s t a t e d , i t i s the t r u e s t measure one can o b t a i n of the stage of s p e c i a t i o n . In search f o r d i s t i n c t i v e c h a r a c t e r s , one seeks those which r e f l e c t i n h e r i t a b l e g e n e t i c d i f f e r e n c e s r e g a r d l e s s of sex, s i z e , and environment.  119 Determining whether two c h a r a c t e r s do o r do n o t i n t e r g r a d e is  a main problem i s s y s t e m a t i c s .  The degree o f i n t e r g r a d a t i o n as  d e s c r i b e d by Ginsburg (1938) and Royce (1957) was employed. As has been s t a t e d i n the previous s e c t i o n s each morphometric c h a r a c t e r was subjected t o r e g r e s s i o n a n a l y s i s . Regression  technique  was chosen because o f i t s value i n morphometric study i n t h a t the s i z e or growth o f one c h a r a c t e r i s r e l a t e d i n a p a r t i c u l a r way to the s i z e o r growth o f another c h a r a c t e r .  A n a l y s i s o f c o v a r i a n c e was used to  compare r e g r e s s i o n l i n e s ; t h i s provides answers as whether two o r more samples d i f f e r more than would be expected from  chance.  The f a c t o r s such as the d i s t i n c t n e s s o r the s i z e o f the gap, the e v o l u t i o n a r y r o l e o r the nature o f the a d a p t a t i o n zone and the degree o f d i f f e r e n c e must be weighed before any d e c i s i o n on the systematic s t a t u s i s to be made. The g r e a t e r the d i f f e r e n c e o r the gap between two c l u s t e r s o f s p e c i e s , the g r e a t e r the j u s t i f i c a t i o n f o r r e c o g n i z i n g both c l u s t e r s as separate taxa.  The d i f f e r e n c e i s  measured not only i n terms o f phenetic d i s t a n c e but i n terms o f biological significance.  The e x i s t e n c e o f a gap i m p l i e s r e p r o d u c t i v e  i s o l a t i o n and t h i s d i f f e r e n c e may be used f o r taxonomic r e c o g n i t i o n o f the s p e c i e s . The d i f f e r e n c e i n t h e u t i l i z a t i o n o f t h e environment i s r e s p o n s i b l e f o r the s i z e o f gap between taxa. The data obtained d u r i n g t h i s study suggest t h a t i n the Java Sea there are only two species o f Rastvelligev, kanaguvta;  and R.  other species a r e reduced t o synonyms. Rastvelligev  waters.  R. bvachysoma  i s d i s t r i b u t e d abundantly i n the Indonesian  This genus i s caught i n the Java Sea and c o n t r i b u t e s s i g n i f -  120 i c a n t l y to marine f i s h e r i e s p r o d u c t i o n .  The problem o f whether  o r not t h i s Rastrelliger  i s composed o f a number o f p o p u l a t i o n s has  not y e t been analysed.  Hardenberg's hypothesis (Hardenberg,  based on Decapterus  m i g r a t i o n patterns d e s c r i b e s the  1938)  Rastrelliger  s t o c k s i n the area and i s the only p o p u l a t i o n study t o have been attempted. In order to approach the above problem and to v e r i f y the h y p o t h e s i s , morphometric s t u d i e s have been conducted.  Four samples  from two d i f f e r e n t f i s h i n g grounds were compared. The r e s u l t s o f the comparisons  o f R. braahysoma  sub-samples  from Tg. S a t a i area suggest t h a t l o n g i t u d i n a l measurements and p e l v i c f i n l e n g t h are s i g n i f i c a n t l y d i f f e r e n t (1%) between sexes (Table 10). These c h a r a c t e r s were d e l e t e d from f u r t h e r morphometric a n a l y s e s . To a v o i d p o s s i b l e bias due to a l l o m e t r i c growth, among R. kanagurta  comparisons  sub-samples from the north coast o f Java were done  by length-groups.  The r e s u l t s are t h a t the p e r p e n d i c u l a r i r i s  diameter and the p e r p e n d i c u l a r p u p i l diameter, p e c t o r a l f i n l e n g t h , and p e c t o r a l breadth are s i g n i f i c a n t l y d i f f e r e n t (1%) among the groups (Tables 11, 12., 13).  These c h a r a c t e r s e x h i b i t s t r o n g a l l o m e t r i c  growth and thus, should be d e l e t e d f o r f u r t h e r a n a l y s e s . The c h a r a c t e r s t h a t do not e x h i b i t e i t h e r sexual dimorphism o r s t r o n g a l l o m e t r i c growth are compared among samples and the r e s u l t s are shown on Table 20.  The data suggest t h a t R. braahysoma  exhibits  geographical v a r i a t i o n i n the d o r s o v e n t r a l depth, g r e a t e s t body depth, and i n t e r o r b i t a l d i s t a n c e , R. kanagurta  i n the head length and the  121 dorso v e n t r a l depth.  T h e r e f o r e , from the standpoint o f morphometry  there a r e two d i f f e r e n t p o p u l a t i o n s o f Rastrelliger  spp. i n the Java  Sea area which supports the Hardenberg hypothesis f o r R.  kanagurta  stocks. The m e r i s t i c c h a r a c t e r s examined do not e x h i b i t i n t e r - o r intraspecific differences. The q u a l i t a t i v e c h a r a c t e r i n d i s t i n g u i s h i n g s p e c i e s i s the appearance o f the c e p h a l i c l a t e r a l l i n e canal system. The l a n d i n g s o f Rastrelliger area.  mostly come from the Sunda S h e l f  In t h i s study, as has been s t a t e d b e f o r e , two s p e c i e s o f  Rastrelliger  a r e r e c o g n i z e d , R. braahysoma  R. kanagurta  o r Kembung L e l a k i .  o r Kembung Perempuan and  Kembung L e l a k i i s caught mostly by  payang-net i n the o f f s h o r e r e g i o n s , w h i l e Kembung Perempuan i s caught i n the c o a s t a l areas by s e v e r a l kinds o f f i s h i n g gears such as g i l l n e t s , s h o r e - s e i n e s , and t r a p s . The data i n t h i s study suggest t h a t the Rastrelliger  fisheries  depend mainly on the 0-year c l a s s which i s completing i t s f i r s t year o f l i f e i n the f i s h e r i e s .  The f i s h a r e immature o r j u s t mature.  The success o f t h i s kind o f f i s h e r y w i l l depend on the s t r e n g t h o f the incoming 0-year c l a s s which i s dependent on the seasonal s u r v i v a l r a t e o f the young, and the c o n d i t i o n s o f the environment t h a t i n f l u e n c e m i g r a t i o n o f the f i s h to the f i s h i n g grounds.  The change i n r e c r u i t -  ment seems to have a s t r o n g e r i n f l u e n c e than f i s h i n g pressure on the f l u c t u a t i o n o f the stock.  The study o f s t o c k - r e c r u i t m e n t r e l a t i o n s h i p s  are a n e c e s s i t y and must be undertaken to r e l a t e the abundance o f the  122 p r e - r e c r u i t phase to age c l a s s strength f o r f i s h i n g success p r e d i c t i o n . The data suggest that the Kembung f i s h e r i e s i n the Java Sea have not y e t reached maximum e x p l o i t a t i o n which suggests the p o s s i b i l i t y of i n c r e a s i n g production by i n c r e a s i n g f i s h i n g i n t e n s i t y .  Since the  p a r e n t - r e c r u i t r e l a t i o n s h i p i s n o t y e t e s t a b l i s h e d the i n c r e a s e should be undertaken c a u t i o u s l y to avoid causing a d e c l i n e i n s u f f i c i e n t enough t o hurt the f i s h e r i e s .  recruitment  However, the " n a t u r a l " c l o s e d  f i s h i n g seasons i n the Java Sea a r e l i k e l y t o keep the f i s h e r i e s i n good c o n d i t i o n .  123 V.  CONCLUSIONS  Analyses o f morphometric data suggest t h a t there a r e two species i n the genus Rastrelliger, R. kanagurta.  ysoma.  R. negleotus  Rastrelliger  braahysoma  and  i s considered to be a synonym o f R.  braah-  Both species e x h i b i t i n t r a s p e c i f i c geographical v a r i a t i o n s  i n the d o r s o v e n t r a l depth, the g r e a t e s t body depth and the i n t e r o r b i t a l d i s t a n c e i n the former s p e c i e s ; and i n the d o r s o v e n t r a l depth and the head depth i n the l a t t e r ones. A n a l y s i s o f catch curves i n d i c a t e s a v a r i a t i o n i n the i n s t a n taneous t o t a l m o r t a l i t y c o e f f i c i e n t ; f o r i ? , kanagurta November 1971 and 1.20 i n December 1971.  i t i s 1.08 i n  I t also indicates variation  i n the s u r v i v a l rates o f the West and East Monsoon Rastrelliger  kanagurta  p o p u l a t i o n s , t h a t i s o f 0.34 and 0.72 r e s p e c t i v e l y . The s u r v i v a l r a t e s o f the West Monsoon p o p u l a t i o n i n 1971 and 1972 are n e a r l y the same. The estimated natural m o r t a l i t y M was 0.40. R. braahysoma  had a s u r v i v a l r a t e o f 0.82 i n the 1971/1972  f i s h i n g season, with an estimated n a t u r a l m o r t a l i t y M o f 0.40. The f i s h i n g m o r t a l i t y F o f R. kanagurta  i n the north coast  o f Java area was 0.83 (December 1971) and i t was 0.44 f o r R.  braahysoma  i n Tg. S a t a i area (1971/1972 f i s h i n g season). In o r d e r to determine the p o t e n t i a l y i e l d o f the f i s h p o p u l a t i o n s , the y i e l d per r e c r u i t models o f Beverton and H o l t (1957) and o f R i c k e r (1958) were employed. The data suggest t h a t y i e l d can be i n c r e a s e d by  124 i n c r e a s i n g the f i s h i n g pressure more than 60% f o r R. kanagurta be doubled f o r R. braahysoma  and can  o f Tg. S a t a i area.  The g r e a t e s t y i e l d f o r both s p e c i e s can be achieved by extending the age o r s i z e o f the f i r s t capture t o 4.5 months o f age (15.5 cm TL) and 4.0 months o f age (12.0 cm TL) r e s p e c t i v e l y . The f l u c t u a t i o n s o f the catch during past years was probably caused by f a i l u r e o r success o f r e c r u i t m e n t r a t h e r than by the i n c r e a s e i n f i s h i n g pressure. The f i s h p o p u l a t i o n s do not appear to be i n a s t a t e o f overe x p l o i t a t i o n , t h e r e f o r e , the f i s h i n g a c t i v i t i e s should be i n c r e a s e d t o gain more food and to i n c r e a s e employment.  However, s i n c e the parent-  . r e c r u i t r e l a t i o n s h i p i s not y e t known, the i n c r e a s e should be undertaken cautiously.  125 LITERATURE CITED A g a s s i z , J.L.R. 1874.  P i s c e s Celebes.  Icones  Piscium,  London.  Barkley, Richard A. 1968. 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C r i t e r i a f o r s u b s p e c i e s , s p e c i e s and genera, as determined by researches on f i s h e s . Ann N.Y. Acad. Sci.,  Jones, R.  44: 109-21.  1957.  A much s i m p l i f i e d v e r s i o n o f the f i s h y i e l d e q u a t i o n . Document No. P. 21 submitted to the Lisbon J o i n t Meeting o f ICNAF/ICES/FAO,  8  pp.  Jones, S. and H. Rosa J r . 1962. Synopsis o f the b i o l o g i c a l data on the f i s h e s of the genus Rastrelliger Jordan and S t a r k s 1908 with an annotated b i b l i o g r a p h y . Symposium on Scombroid F i s h e s , Marine  Biol.  Assoc.  India,  III:  1190-1236. Jones, S. and E.G. S i l a s .  1962.  Mackerel from Andaman Sea.  Symposium on Scombroid F i s h e s . India, I: 255-82.  Marine  Biol.  Assoc.  Jordan, D.S. and M.C. Dickerson. 1908. On a c o l l e c t i o n o f f i s h e s from F i j i with notes on c e r t a i n Hawaiian f i s h e s . Proc. U.S. Nat. Mus.  3  34: 603-17.  Jordan, D.S. and F.S. S t a r k s . 1908. 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Neue W i r b e l t h i e r e . Meeres: 10-38.  F i s c h e des Rothen  Schaefer, M.B. and R.J.H. Beverton. 1963. F i s h e r y dynamics i n t h e i r a n a l y s i s and i n t e r p r e t a t i o n . In M.N. H i l l ( e d i t . ) , The Sea, Interseienoe, N.Y., 2: 463-483. S i l a s , E.G. 1962. P a r a s i t e s o f Scombroid F i s h e s . Scombroid F i s h e s . Marine  Biol.  Assoo.  India,  Symposium on  I I I : 799-875.  Sheshappa, G. 1958. Occurrence o f growth checks i n the s c a l e s o f the Indian-mackerels, Rastrelliger kanagurta cuvier. Current  Sci.,  27: 262-63.  SSentongo, George W i l l i a m . 1971. Y i e l d equations and i n d i c e s f o r tropical freshwater f i s h populations. M. So. Thesis,  Dept. Zoology,  U.B.C.  S t a r k s , E.C. 1921. A Key to the F a m i l i e s o f Marine F i s h e s o f the West Coast. C a l i f o r n i a S t a t e F i s h and Game Comm. Fish. Bull.,  5: 16 pp.  Tesch, F.W. 1968. Age and Growth. j_n W.E. R i c k e r ( e d . ) , Methods f o r Assessment o f F i s h P r o d u c t i o n i n Fresh Waters. IBP,  London,  313 pp.  Tiews, K. 1958. Report to the Government o f the P h i l i p p i n e s on Marine F i s h e r y Resources. Phil.  J. Fish.,  6 ( 2 ) : 107-208.  V a n i c h k u l , P. and V. Hongskul. 1966. o f chub-mackerel {Rastrelliger T h a i l a n d . Proo. Indo-Pacif.  Length-weight r e l a t i o n s h i p s spp.) i n the G u l f o f Fish. Coun., 11(2): 20-23.  135 van Kampen, P.N. 1907. Uber Zwei Scomber - Are tn des Archipels.  Bull.  Dept. Agric.  Indes.  Neerl.,  indischen 8(Zool. 2):  1-8. Van Oosten, John. 1957. The s k i n and s c a l e s . Jto M.E. Brown e t a l . , The P h y s i o l o g y o f F i s h e s New York, Academic P r e s s , 1957. von B e r t a l a n f f y , L. 1934. Untersuchungen uber d i e G e s e t z l i c h k e i t des Wachstums, Arch. Entw. Mech. Org. Berlin, 131: 613-652. . 1938. A q u a n t i t a t i v e theory o f o r g a n i c growth. Hum. Biol.,  10: 181-243.  . 1957. Q u a n t i t a t i v e laws i n metabolism and growth. Q. Rev. Biol.,  32: 217-31.  Wilimovsky, N.J. and E.C. Wicklund. 1963. Tables o f the incomplete Beta f u n c t i o n f o r t h e c a l c u l a t i o n o f f i s h p o p u l a t i o n y i e l d , Vancouver, Univ., B r i t i s h Columbia, I n s t i t u t e o f F i s h e r i e s , 291 pp. . 1972. L e c t u r e s on F i s h e r i e s B i o l o g y and Management and I c h t h y o l o g y , U n i v e r s i t y o f B r i t i s h Columbia, Vancouver, B.C., Canada. Whitley, G.P. 1944. New Sharks and f i s h e s from Western A u s t r a l i a . Australian  Zoologist,  10: 252-73.  136a  c  A P P E N D I  CES  Body measurements of R a s t r e l l i g e r .  CO  137  5  10  15  20  25 (X 1000)  Figure  TOTAL EFFORT  14 a. R e l a t i o n between T o t a l E f f o r t and C a t c h P e r U n i t of E f f o r t ; and between T o t a l E f f o r t and T o t a l C a t c h of R. k a n a g u r t a from t h e n o r t h c o a s t of J a v a i 1971. T h i s i s the s i m p l i f i c a t i o n o f F i % u r e 14; f i t t e d by eyes. n  Catch I (X 1 0 t o n s !  140  40 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0  •i  1  2  1  3  »  4  1  5  6  —I**  1  \  1  1  7  8  9  10  11  r  12  1971  28. Monthly p r o d u c t i o n s o f t h e n o r t h coast o f Jev i n 1971. A. R. kpnpgurta; B. Decautprus snn.t C, Euthynnus snn.  141  %  40 ••  30 . .  20 +  10  1  o •  '  17.0  1  1  > 5  1  18.0  1  1  > 5  19.0  — 5  I 20.0  J > 5  21.0  I  I  < 5  22.0  I >  1=3= s  23.0 TL (cm)  Figure 29.Frequency d i s t r i b u t i o n Java Sea (1972) .  of mature R. kanagurta from the  142  T /R w  1.0 t c R. kanagurta. R. Figure  brachysomp.  30. Y i e l d per r e c r u i t es a f u n c t i o n o f t w i t h f i s h i n g m o r t a l i t y F ranged from .1 t o 1.5. 0  143 TABLE 37 Rastrelliger  Month  braahysoma  1968 (ton)  Productions o f Tg. S a t a i Area 1969 (ton)  1970 (ton)  360 373 511 136 64 9  600 712 584 281 120 56  I II III IV V VI VII VIII IX X XI XII  70.6 287  120 592  85 239  Total  1,621.1  2,165  2,678  Source:  357 398 303 143 55 7.5 -  ••  _  •  -  _  -  -  _  -  -  _  The Sea F i s h e r i e s S e r v i c e o f t h e Province of West Kalimantan (Borneo) i n Pontianak.  144 TABLE 38 Age D i s t r i b u t i o n o f R. braahysoma i n Tg. S a t a i Area i n 1971/1972 F i s h i n g Season Age (Month)  Frequency  %  4  12  .75  5  27  1.7  .5195  6  190  11.8  2.4707  7  263  16.4  2.7958  8  116  7.2  1.9773  9  450  28.0  3.3329  10  327  20.4  3.0136  11  206  12.8  2.5515  12  13  .81  .2114  13+  2  .13  2.0832  In % .2914  145  TABLE 39 Age Distribution in the Catch of R. kanagurta  Age (Month)  West Monsoon 1971 (f)  East Monsoon 1971 (f)  in the Java Sea  West Monsoon 1972 (f)  4  -  4  -  5  -  16  -  6  -  32  1  7  24  33  5  8  22  27  8  9  70  23  24  10  no  22  52  11  30  21  14  12  15  16  7  6  9  4  13+  146  TABLE 40 Average E f f o r t o f a Payang-Boat i n 1971 i n the North Coast o f Java n = 8 boats; power = 20 H.P.; crew = 16 Fishing Trip  Month  F i s h i n g Day  I  22  4  II  10  2  III  22  4  IV  14  3  V  17  3  VI  14  3  VII  13  3  VIII  12  2  IX  16  4  X  18  4  XI  13  2  XII  16  4  Total  187  38  Average  15.6  3.2  147 TABLE 41 i?.  Month  kanaguvta  S t a t i s t i c s i n 1971 i n the North Coast o f Java  T o t a l Catch (kg)  Catch/Boat/Day (CPUE)  Effort =  T o t a l  C a t c h  C/B/D  I  535,004  19.2  27,865  II  520,879  26.6  19,582  III  863,163  65.4  13,198  IV  1,156,411  51.9  22,282  V  1,002,515  78.2  12,820  VI  934,393  125.2  7,463  VII  739,127  148.3  4,984  VIII  587,734  25.6  22,958  IX  869,431  38.8  23,626  X  1,010,473  62.6  16,142  XI  1,032,547  176.4  5,853  XII  905,458  130.8  6,923  

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