Prawn seed resources of Sunkeri back waters indicated the availability of Penaeus indicus, P. monodon, Metapenaeus dobsoni and M. monoceros. The monthly variation in seed composition, its correlation with environmental parameters and the aquaculture potentialities are reporte

Anil, A.C.

Prawn seed resources of Sunkeri back waters indicated the availability of Penaeus indicus, P. monodon, Metapenaeus dobsoni and M. monoceros. The monthly variation in seed composition, its correlation with environmental parameters and the aquaculture potentialities are reported

Anil, A. C.

Publications of the IAS Fellows

Journal of the Indian Fisheries Association, 
12 & 13, 1982-83, 13-20 
PRAWN SEED RESOURCES AND ITS FARMING POTENTIALITIES IN 
SUNKERI BACK WATERS (KALI ESTUARY- KARWAR) 
A. C. ANIL 
National Institute of Oceanography Dorw-Paula, Goa-403 004 
ABSTRACT 
Prawn seed resources of Sunkeri. Hack Waters indicated the availability oC 
Penacus iudicus (H. Milne Edward":.), Penacus monodon (Fabricius) Meta-
pe-!U:tells dobsoni (Miers), and lvletapenueus monoceros (Fabricius). The 
monthly variation in seed c:ompositiop, its correlntion w1th environmental pan\~ 
meters and the aquaculture poteiltialiti.-.s are being r~ported. 
INTRODUCTION 
With the jncreasing demand for aquafanning, the need for production of 
quality seed has become a most vital factor. \Vhile this goal is attained to a 
good extent by induced breeding teclmiques in fresh: water fishes, same amount 
of success is yet called for in the field of brackish water aquaculture. 
It is a we11known fact that tltc estuarine areas are the most potential nursery 
grounds for the :young prawns. Consequently these water bodies fonn tlle mo2.t 
important pr~.wn seed collecting centres. With this· position in view, studies on 
the prawn seed resources were under· taken in Sunkeri back waters which is a 
major fishing centre of the Kali estuary. 
DESCRlPTION ON THE SITE 
Kali esw.ary joins the Arabian sea a~ RJrurwar ( l4 a 51• N lat and 7 4 o 7 ' E 
long) . The tidal influence of this estuary extends upto about 29 Krns (M. 
Nagaraj, personal communication) Ba:ck water s-ystem of lhis estuary 1s 
moderately well developed owing to the availability of the low lying areas. 
The Sunkeri backwater lies on the southern side !Jt the estuary and is ab01.1"' 
3 kms away from the mouth of the estuary (Fig. 1) . It is connected \Vith Ka!i 
estuary through a narrow neck channel, which supports mangroves and grass land. 
The backw~~ter is divided into two by a bund which serves as the road link 
between Sunkeri on the west and Kadwad on the east. The bund has a bridge 
provided with 29 wooden sluice gates, which control the water movement. 
14 ANIL 
111111 SLUICE GATES 
'*. GRASS LAND 
(9 MANGROVE 
Fig, 1. Location of Sunkeri backwaters. 
s 
The backwater harbours different types of vege·tartion, on the southern side 
of the bund, at the eastern half there is a grassland which is submerged most of 
the time. The mangroves on the southern s~de of the bund are sparsely distri-
buted, where as that on the northern side the concentration is considerably 
more. The depth of the water column increases gradually from the eastern S·ide 
to the' western side. Wave action is almost negligible through out the area. 
MATERIALS AND METHODS 
The period of observation was from November 1980 to April 19~1. Water 
samples were collected from Sunkeri backwaters at fortnightly intervals. Water 
temperature was measured on the spot using thermometer. Water samples were 
analysed in the laboratory fdr salinity and dissolved oxygen following the standard 
methods given by Strickland and Parsons (1968) . pH was measured using the 
pH meter. 
Prawn seed collection was made at the same intervals during low tide from 
.different places i.e. mangroves, low lying area, and channel connecting the 
estuary, using a dragnet of 12 1 x 6 1 with a mesh srize of 2mm . The net was 
dragged against the wate,r current in shallow waters within 1 meter depth for 
at distance of two meters, each time. The total operation period in each locality 
was about one hour. 
PRAWN SEED RESOURCES OF KALI ESTUARY 15 
Identification and segregation of the seed were made in the laborator'/ 
following the standard key (Rao and Gopn1krishna, 1968; Rmo, 1969). Prawn 
seed samples were measured for their total length (tip of the rostmm to tip of 
telson). 
RESULTS ANb DISCUSSION 
The prawn seeds encountered during: the study period wcro those of 
penaeus indicus (H. Milne Edwards), Penaeus mono don (Fabricius), Meta~ 
Penaeus dobsoni (Miers), Metapenaeus monoceros (Fabricius). 
All the above penacid spp. migrate to the estuaries and backwaters where 
they are avn.ilable in the mysis nr early post larVal stages. They sper d D 
part of the ·life in these ecosystems before returning to the sea (Project report 
on assessment of aultivabJe penaeid prawns at selected centres in Kcrala a:nd 
Karnatalm. 1980.) It is this phaLSe of their life that constitt1tes the seed resource'5 
in the estuaries and buckwaters. 
Prawn Seed Composition : 
The percentage conlpo:sition data showed a gradu.a1l increase in the percen-
tage cohlposition of the seeds of P. indicus from November to Marcn. During 
AprJl it declined slightly, but maintaining. relatively higher. values than those of 
November to Febmary montns. (Table 1). 
Table I : Prawn Seed composition (Values given as percentage) 
SpcQies Nov. 80 Dec. Jan. 81 Feb. Mar. Apr. Total 
average 
P. indic~ls 22.22 25.00 25.00 25.64 41.66 32.25 28.63 
P. monodon $.55 8.33 6.18 7.64 4.63 
M. dobsont 13.33 33.33 40.90 38.46 22.22 48.38 36·10 
M. monocerQs 38.88 33.33 27.27 28.20 36.1! 19.7$ 29.·69 
P. monodon seedJ:> made their contribution during November to· February 
to the total composition. During. the months of December and Febn1ary tbc 
values were higher but .disappeared thereafter. 
M. dobsoni seed composition steadily increased from November to Janua.t'y 
and then SJcaled down, but reached peak in the month of April, its contribwtio,r· 
being about 48.88% of the total prawn seeds (Table l). 
The M. monoceros seeds contributed maxiinum during the months of 
November and March. Its least contribution was foti.nd in April. During the 
16 ANIL 
months oif November, M. monoceros seed constituted the major portion of 
pr,awn seeds (38. 88%). During December M. dobsoni and M. monoceros 
took equal shares (33. 33%). In January, February, and April the seed of 
M. dobsoni was domincnt' i.e. 40.90%, 38.46% and 48.38% respectively. 
In March, the seed of P. indicus formed the dominant spedes and its contribu .. 
tion to percentage composition was 41.66% . 
On the who1e, the percentage contribution of M. dobsoni w.a:s highest during 
November to April period (36 .10%) followed by M. monoceros (2Q. 69%), 
P. indicus (28.63%) and P. monodon (4.63%). 
45 
40 
35 
30 
E 25 
E 
IV 
N 
. 
en J5 ,-
I• 10 
5 
-·--·-
I"""- v r-·-
v F""·-
!-·-
( 
1/ 
;. 
I 
o-t\ // 
6- r-~\ N lI 
I 
1\1 
.l:. 
N 080 J F M A81. 
f. indicus 
'T 
I 
I 
N 080. J F M A81, 
M. dobsoni 
--·- Mmtimum 
o---o Dominant 
6---....o Minimum 
N 080, J F M A81. 
M. monoceros 
Fig. 2. Size Variation in different Species of prawn larvae 
Size Ranges : 
The seed of P. indicus obtained during the period of November to February 
had a size range of 10 to 40 mm and those obtained during March and April 
had 25 to 45mm size range .. 
PRAWN SEED RESOURCES OF KALI ESTUARY 17 
r..mperature •c 
.. ·=== 
pH 
Saliflit~ %e 
00 
(/) 
..., 
29 
:l 
...J 
<( 20 
> 
'' 
10 Dinolved ORygen mlllilre 
fl 
0 
NOV 80 DE9 80 JAN 81 P'll:ll $1 MAR 81 API! Ill 
PERIOD 
Fig. 3. Variatiomrin some -Physico Chemical parameters at Sunk.eri backwater. 
P. monodon seed obtadned had a size range of 15-40mm. M. dobsoni 
seed collected during November to January period had a size range of 9 to 
35mm and the ones collected in February and March had a size range of 10 .. 
37mm. The seed of M. dobsoni collected during April showed a size range of 
30 to 40mm. 
M. monoceros seeds obtadned during November-December had a size range 
of 12-40 mm and during Janua,y to March the range was 10-30 mm. In April 
the size range of these was between 20-30 mm. 
Environmental Parameters : 
During the period of investigation. the variations in temperature, salinity, 
dissolved oxygen and pH were· respectively 27 .2-29.5°C, 27-32%o, 4.59-6.91. 
ml/litre, and 6 . 8 to 8 . 0 . 
ANIL 
The vadation in the salinity, temperature, dissolved oxygen during the 
study period faDs with in the 'ideLtl range of paralJleters suggested by 
C.M.F.R.I. (Kartha and Nair, 1980). 
However, it was observed that the maximum abundance of all sp~·cies of 
prawns available was found in the months of December ;:1nd January. During 
these two months salinity (28. s· to 30. 5%0) and te~erature ( 27.2 oc to 
27. 4 oc) were comparatively lower compared to the period from February to 
April (31-32%o and 27.7-29. 5°C). However, during December-Jamwry ih~~ 
dissolved oxygen content (5. 45-6.91 ml/litre) was higher than that of Fcbmat")) 
to April period ( 4. 42 to 6. 81 ml/litre) . ln case of P. monodon the secu;; 
were totally absent during March to April when the salinity was comparativeiy 
higher than the previous 4 months. 
Aquaculture potentialitifs : 
The lowlying area extends to about 200 acres with water depth ranging' 
from 1 . 5 to 1 feet. The variations in the environmental parameters during the 
study period fell with in the range that is ideal for a.quafarming. fiowevc:·, arrwng 
the different parameters, the pH needs special consideration before establishilw 
commercial aquafarrning in the area. The v,ariation in pH is from 6 . 8 to 8 . 0 and 
the pH range between 7. 5 to 8. 5 is best ..,uited for aquafarming (Kartha and 
Nair, 1980). 
The. problem of controlling this fa1ctor is being achieved by liming the farm 
before filling wate:r (Jhingran, 1975). During the p3riod of observation it wa:~ 
found that the availability of P. morwdon was very poor and 'Vas totally absent 
during Feb;ruary to April period. The ea:rlier stlldtes carried out by Nagaraj 
and Neelakantan (1980) in the Kali estuary has indicated that the seed of 
P. monodoh .was more abundant during the e.airly parr··of. monsoon He1ke con-
sideration of this factor is very es·semial, if monoculture of P. monodon is to 
b~· un'dertake:n iti. this ·area during the November to April period. 
The distribution of ·mangroves on the margin:s is also advantageous 'sine·~ 
the mangrove· leaves· upon· falling into the water get deca.yed by bacterial action .. 
there by enriching the area with mltrients (Saundararaj 1978) . 
!t has been bbserved that the area has seed potentiaJity for. the finfi.~hesJike­
Mullet, Etroplus suratensis, Scatophagus argus. Sillago sihmna. 
The methods of prawn seed collection in this ar~a. nre wo:r.th .01.1r attentipn. 
since it is an important prerequisite for aqua[ arming. The most common method 
is" by· os.ing ::a ·dragnet of" a m:csh size .'2. to·· 6 -rr:lm This: method :is maiilly lused 
fdr the. colleQtion.:..ofCseed ranging ftorn 0. 5 to 2 clh in .length. Howeve1\ .seedS 
PRAWN SEED RESOURCES OF KALI ESTUARY 19 
of relatively bigger size i.e. upto 3 em are usually preferred and as such cast 
net is also used for such collections; 
Another common method under practice for the collection of seed is by 
constructing ounds in the ·shallow water areas forming srriall jmpoundments into 
which the seed enriched water gets entra:pped at the time of high tide and this 
seed is scooped out during low tide. Further, some fishermen adopt the pit 
collection~ where in small pits are made in the shallow intertidal area into which 
the seed enriched water enters Rnd thus entraped seed is easily ScOoped OUt dur· 
ing low tide . However this method is not very common. 
Though a variety of seed colleoting me-thods arc known from different 
parts of our country, the methods followed along the Kali estuary are rather 
simple and less efficient. The gear such as midnapore shooting net common along 
West Bengal and hapa nets are not used despite their high efficiency 
At present the prawn culture is carried out at two places-Kadwad and 
Hottegali, adjacent to the Kali estuary. The total area under culture is abont 
200 acres when compared to the existing areas around Kali estuary, this iS 
meagre. Since the stocking is done just by allowing the seed enriched waters 
during high tide into the fawms, the need for actual collection of seed and then 
stocking is not actually felt. However, the seed collection is practiced to a little 
extent and this seed collection for stocking is usually restricted to P. monodon 
and P. indicus. It is thus clear that the present rate of exploitation of seed as. 
a whole is not high, compared to the relative abundance of the seed and the vast 
scope for expanding the operations. 
ACKNOWLEDGEMENT 
I am greatly indebted to Prof. B. Neclakantan, Head of the Department 
P. G. Dept. of Marine Biology, Karnatak University Karwa:r for his guidance 
during the study period. I thank Mr. M. Nagaraj, Research Fellow, for his 
kind co-operation. 
REFERENCRS 
C. M. F. R.I. , 1980. Project report on .assessment of fry resource of Cultivable 
penadid prawns at selecte·d centres in Kerala and Karnataka . 
Jhingran, V. G. , 197 5 . Fish and Fisheries of India : 4 72 pp. 
Kartha, K. N. R. , and Nair, P. K., 1980. Krishi vigyana patrika, M aricu}p 
ture, series~S. Krishi Vigyana Kendra, C. M. F. R.I. Narakal, 13pp. 
20 ANIL 
Nagaraj M. and 'Neclakantan, B. 1980. Fish and ·shell fish seed resources ·ot 
Kali estuary along with the note on the Mariculture potentiality in Uttara 
Kannada. M .B .A .1. Symp. coastal aquaculture Cochin. Abst. No. 108. 
Rao; M. a:nd Gopalkrishnan,. V. 1968 . Identification of the juveniles of the 
prawns ·P. monvdoi1· and P. · indicus. Indo .Paci(zc fish. Council Proc • 
13th sess. Brisbane Queensland Australia. 128.,.131 . 
Rao, V. 1969. On .the identification of juveniles of three Spp. of MetapenamJ.s 
(Decapoda, Penaeidae.). Indian!. Fisheries 16: 5lpp.. 
Strickland, J . ..J. H. and Parsons, T. R.; 1968. A practical1tand book for 
Sea water analysis. Bull. 169. Fish. Res. board of Canada 167: 311 pp. 
Saundararaj V., 1978. Suitability of mangrove biotope for brackish water aqua· 
cultnre. Seafood export jour 10: No. 12. 


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Prawn seed resources and its farming potentialities in Sunkeri back waters (Kali Estuary - Karwar)

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Prawn seed resources and its farming potentialities in Sunkeri back waters (Kali Estuary - Karwar)

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