Specimens randomly collected from Sassoon Docks, Bombay, India, at monthly intervals during 1979 to 1981 were considered for age/growth studies. Cynoglossus macrolepidotus, the fish, attained a length of 202 mm at 1 year, 250 mm at 1 1/2 year and 272 mm at 21 months respectively; the maximum length of the fish could be 353 mm and the life span could be 7 years. The scale ring studies showed presence of only 0 to 3+ rings. Majority of the fishes were of 1 and 1+ year class

Dwivedi, S.N.

Rao, M.R.

Aquatic Commons

Journal of the Indian Fisheries Association 
19,1989,43-48 
LENGTH FREQUENCY AND GROWTH STUDIES ON 
CYNOGLOSSUS MACROLEPIDOTUS (BLEEKER) OFF 
BOMBAY COAST 
MAITHILI R. RAO AND S.N. DWIVEDI° 
Department of Biological Sciences, Ramnarain Ruia College, 
Matunga, Bombay-400 019 
ABSTRACT 
Specimens randomly collected from Bassoon Docks at 
monthly intervals during 1979 to 1981 were considered for 
age/growth studies of Cynoglossus macrolepidotus. The fish 
attained a length of 202 mm at 1 year, 250 mm at 1 1/2 year and 
272 mm at 21 months respectively and that the maximum length 
of the fish could be 353 mm and the life span could be 7 years. 
The scale ring studies showed presence of only 0 to 3+ rings. 
Majority of the fishes were of 1 and 1+ year class. 
INTRODUCTION 
Several authors have studied age and growth in many commercial fishes. For 
determination of age and growth in flat fishes, methods used are check of scales 
on the snout and length-frequency distribution. Seshappa and Bhimachar (1954) 
and Kutty (1967) have studied the age and growth of some cynoglossids. Studies 
on the ecology and biology of Cynoglossus macrolepidotus were made by Rao 
(1985). According to Devaraj (1983) it is diffcult to arrive at reliable age-length key 
for tropical fishes due to problems arising mainly from protracted spawning and 
multiple broods comprising individual year classes. However, when familiar 
method of length-frequency analysis for age determination is appropriately 
modified it serves the purpose of age determination of tropical fishes (Devaraj, 
1982). Hence this method was followed in the present study to determine the age 
and growth of C.macrolepidotus. 
° Present address Department of Ocean Development, Mahasagar Bhavan, Block-92, COO 
Complex, Lodi Road, New Delhi-110 003. 
44 	 RAO AND DWIVEDI 
MATERIAL AND METHODS 
4646 specimens of C. macrolepidotus were collected at monthly intervals from 
Sassoon Docks from December 1979 to February 1981. Specimens ranging from 
70 to 350 mm were measured and grouped into size groups of 10 mm interval. 
A single frequency polygon was prepared. The modal lengths for each month 
were plotted for the scatter diagram technique of modal progression analysis 
(Devaraj, 1982). The trend in the progression of the modes through time was then 
indicated by an eye-fitted line. The fitted line was extrapolated freehand with 
reference to the intermodal slopes, so that it intersected the time axis indicating 
the time of brood origin, the number of broods per year class, the periodicity of 
brood release, the growth of the brood since its origin through successive months 
and approximate longivity of the fish. From data, the mean length at age was 
estimated. The mean length at age data was used for the estimation of the growth 
parameters according to Von Bertlanffy growth equation (Bagenal, 1955). 
Lt = L« (1 	 e -K(t-t o ) 
where Lt = length at age t 
assymptotic length 
e = the base of natural logarithm 
K = the growth coefficient and 
to  = the arbitrary origin of growth 
The scales on the eyed side from the pectoral region below the mid lateral line 
were collected by rubbing with wet hand. The scales were mounted on slides and 
observed under microscope for the number of rings. 
RESULTS AND DISCUSSION 
The length-frequency graphs were polymodal indicating that C. macrolepidotus 
is a protracted spawner (Fig. 1). Studies on maturation and spawning showed that 
this fish had spawning activity from June to December. Length frequency 
distribution showed that the fishes of smaller sizes occurred in higher 
percentages during January and February 1981, indicating that there was 
recruitment of the new brood into fishery during this period. 
When growth parameters were estimated, the following results were obtained. 
K = 0.07054 (on monthly basis) 
= 353 mm 
t 	 = -0.0161 (month) 
0 
40 
1.L3 0 
0 
ICY 
tal 
0 0 
0. 0 
to- 
JAN 81 
DEC 80 
NOV 80 
OM' 80 
SEP 80 
AUG 80 
JUL BO 
JUN 00 
MAY 80 
APR 80 
MAR SO 
FED 00 
JAN 80 
DEC T9 
0 
460 	 200 	 250 	 300 
GROWTH STUDIES ON CYNOGLOSSUS MACROLEPIDOTUS 
45 
E8 81 
TOTAL LENGTH IN mm 
Fig. 1 Length - frequency distribution of C. macrolepidotus 
46 
	 RAO AND DWIVEDI 
From the results as given above it was seen that at t o , the age of the fish was 
-0.0161 month, at T.0, approximately 7 years and finally attained a maximum 
length of 353 mm. This data was in confirmation with the only report on C. 
macmlepidotus, indicating that the life span of the fish is 7 years (Kutty, 1967). 
Thus the Von Bertlanffy growth equation for this fish may bewritten as 
Lt 353 [1-e -0.07054(t+0.0161), 
0 0 
0 	 0 
280 
260 
E 
z 240 
X 22 
200 
w 
'41 460 
0 
1— 140 
X 420 
100 
LL/ 
80 
eo 
0 40 
J F1AAMJJAS0NDJ FMAPAJJ ASONDJF 
19 79 	
 I 	 1980 — -9981 
MONTHS 
Fig.2 . Scatter diagram of modal length-month. 
GROWTH STUDIES ON CriOGLOSSUS MACROLEPIDOTUS 
	 47 
The scatter diagram technique of modal progression analysis (Fig. 2) had 
shown that the respective length of fish were 70, 124, 168, ?02. 250 and 272 mm 
at 3, 6, 9, 12, 18 and 21 months. (Table I). This was confirmed by the application 
of Von Bertlanffy growth equation. It was observed that theoretical lengths and 
observed lengths tallied (Table I). In scale ring study three growth rings 
Table I: Estimated growth parameters and mean empirical length and calculated length 
(Von Bertlanffy growth equation) 
Age in months Estimated 
Length at each month in mrn 
parameters Mean 
empirical 
Von Dealer-iffy 
growth equation 
1 L = 353 mm 28 24.32 
2 52 46.84 
3 K = 0.07054 per month 70 67.63 
4 92 86.98 
5 
6 
t 
0 
= -0.0161 110 
124 
105.12 
122.14 
7 140 137.88 
8 155 152.43 
9 168 162.59 
10 180 178.87 
11 194 190.69 
12 202 201.77 
13 214 212.08 
14 220 221.61 
15 230 230.61 
16 237 238.98 
17 244 246.71 
18 250 253.98 
19 258' 260.69 
20 265 267.15 
21 272 272.83 
were observed 
	
and there was 	 growth beyond the third ring in a 
few fish studied but not a single fish with four rings was found. Fish obtained 
mostly belonged to 0, 1 and 1+ year groups. Fish with no rings ranged from 115 
to 214 mm. The 204-214 mm and 214 to 224 mm length groups had the first ring 
just being formed although fishes of 1+ ring group ranged from 165-234 mm 
which according to the length frequency studies were about 9 to 15 months old. 
Since the median of this range is 12 months it may be assumed that the first ring 
was laid down at an age of one year. The 2+ ring group fishes, the length ranged 
from 185-294 mm which according to the length frequency studies were 11 to 25 
months. As the median of this range is 18 months, it may be assumed that the 
second ring was laid down when fish was about 18 months old. The 3+ ring group 
fishes ranged from 234 to 304 mm which according to the length frequency 
studies were 15 to 28 months and hence the median of this range, 22 months, 
may be taken as the age at which the 3rd ring was formed. 
48 	 RAO AND DWIVEDI 
The commercial fishery of this fish consists mainly of zero and 1 year classes 
with a length ranging from 170 to 250 mm. This group consists of 84.38 percent of 
the total catch of the species. However, this fish is included under miscellaneous 
category as per the fish landing data for Bombay zone. 
ACKNOWLEDGEMENTS 
The authors record their thanks to Dr. M. Devaraj, CIFE, Bombay for his help 
and valuable suggestions. 
REFERENCES 
Bagenal, T.B. 1955. The growth rate of the long rough dab Hippoglossoides 
platessoides (Fabr.). J. Mar. Biol. Ass. U.K. 34 : 297-311. 
Chugunova, N.I. 1959. Age and growth studies in fish. English version 
published in 1963 by office of Technical Services. Washington, D.C. 132 pp. 
Devaraj, M. 1982. Age and growth of three species of seerfishes Scomtreromorus 
commerson, S. guttatus and S. lineolatus. Indian J. Fish. 28 : 104-127. 
Devaraj, M. 1983. Fish population dynamics course manual. CIFE. Bull. No.3 (10) 
: 98 pp. 
Kutty, M.K. 1967. Observations on the growth and mortality of the large scaled 
tongue sole Cynoglossus macrolepidotus (Bleeker). Proc. Nat. Inst. India. 33 
B : 94-110. 
Rao, M.R. 1985. Ecology and biology of the flatfish Cynoglossus macrolepidotus 
(Bleeker, 1851) Off Bombay Coast. Ph.D. Thesis, University of Bombay. 
Seshappa, G. and Bhimachar, B.S. 1954. Studies on thr, age and growth of the 
Malabar Sole Cynoglossus semifasciatus Day. Inds. J. Fish. 1 : 145-162. 


Length frequency and growth studies on Cynoglossus macrolepidotus (Bleeker) off Bombay coast

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Length frequency and growth studies on Cynoglossus macrolepidotus (Bleeker) off Bombay coast

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