Spawning success in relation to the size of spawner, clumping of eggs, percentage of spawning and frequency of spawning was studied in Penaeus monodon collected off Tamil Nadu, India. The results indicated positive correlation between the size of spawner and the fecundity and hatching percentage, but not the start of hatching. Hatching characteristics were influenced by clumping of eggs or abortive spawning; the greater the clumping, the longer the time taken for hatching, resulting in a lower hatching percentage. The start of hatching time increased when the frequency of spawning increased. Lower hatching rate was observed as the frequency of spawning increased

Babu, M.

Kitto, M.R.

Marian, M.P.

Ravi, C.

English

Aquatic Commons

13Naga, The ICLARM Quarterly (Vol. 24, Nos. 1 & 2) January-June 2001
Factors Determining Spawning Success in
Penaeus monodon Fabricius
M. Babu, C. Ravi, M.P. Marian and M.R. Kitto
Abstract
Spawning success in relation to the size of spawner, clumping of eggs, percentage of spawning and frequency
of spawning was studied in Penaeus monodon. The results indicated positive correlation between the size of spawner
and the fecundity and hatching percentage, but not the start of hatching. Hatching characteristics were influenced by
clumping of eggs or abortive spawning; the greater the clumping, the longer the time taken for hatching, resulting in
a lower hatching percentage. The start of hatching time increased when the frequency of spawning increased. Lower
hatching rate was observed as the frequency of spawning increased.
Introduction
Aquaculture plays a major role in
increasing fish production in tropical
countries like India. India’s vast
coastal belt and conducive
environment has led to the rapid
expansion of shrimp farming
activities. The tiger shrimp Penaeus
monodon contributes a major share
to shrimp production in India. If
management of a hatchery is to be
successful, full attention must be
given to the processes of spawning
and hatching. Many researchers have
optimized different conditions like
light, temperature, pH and oxygen for
successful spawning and hatching.
But few studies have been done on
other factors which affect spawning
success such as size of spawner,
clumping of eggs or abortive
spawning, percentage of spawning
and frequency of spawning. This
paper discusses the results of a study
of factors in spawning success
carried out on P. monodon.
Material
and Methods
Adult P. monodon were collected
from the sea at Ovari and
Idinthakarai off Tamil Nadu, India,
during the month of August 1999.
One hundred males and 100
females weighing more than 75 g
and 125 g each respectively, were
selected. The selected animals were
transported to the hatching site in a
special tank (Babu and Marian
1998). On arrival at the hatchery,
the animals were treated with 50
ppm formalin for 10 minutes. The
treated animals were then
transferred to the maturation tank
in 1:1 ratio (male and female) and
fed with squid and crab meat at
15% of body weight. Sardines and
encapsulated adult Artemia were
also given at 20% of body weight
daily (Babu and Marian 1998).
From the second day of stocking
50 – 100% water was exchanged in
the maturation tank.
One hundred female spawners
were unistalk ablated after five days
of collection from the sea. The time
of ablation was determined by the
health condition of the spawners. The
maturation room was provided with
photoperiods of 12 hrs light and 12
hrs darkness. The temperature,
salinity, dissolved oxygen and pH
were maintained at 30 ± 1°C, 30 ±
1ppt, 5 mg/l and 7.5 ± 0.5 respectively.
The water used in the maturation
system was not chlorinated but was
filtered through a gravity flow sand
filter. The maturing animals were
treated with 2 ppm Furozolidone and
0.2 ppm Treflan for bacterial and
fungal diseases respectively.
Start of hatching was assessed by
checking five 500 ml glass beakers,
each containing 100 eggs, collected
from the spawning tank with the
water taken from the same tank.
Strong aeration was allowed in both
the tank and glass beaker in order to
keep the eggs in suspension. In order
to assess the start of hatching, the
eggs present in the beakers were
observed  every 10 minutes, 14 hrs
after spawning. Percentage of
hatching was calculated 19 hrs after
spawning. The calculation was made
by counting the hatched-out nauplii
from  five samples taken at different
places of the hatching tank with a
100 ml beaker.
Total number of eggs in the
hatching tank was calculated by
taking 10 samples in different places
of the spawning tank by random
sampling using a 100 ml beaker.
a
q
u
a
b
y
t
e
14 Naga, The ICLARM Quarterly (Vol. 24, Nos. 1 & 2) January-June 2001
Clumping of eggs was noted
even in the highly aerated spawning
tank under optimum conditions. The
percentage of clumping was
calculated by weighing the clumped
and individual eggs separately by an
electronic digital balance. From the
total of both clumped and individual
eggs, the percentage of clumping
was calculated. Ten animals of
different size groups were studied
for relationship between percentage
hatching and size of spawners and
hatching; size of spawners and
fecundity; percentage clumping and
hatching rate/time.
In the case of partially spawned
spawners, the spawned eggs were
collected separately and weighed. The
remaining unspawned eggs were
taken out along with the ovary by a
longitudinal incision on the dorsal side
of the animal. All eggs were carefully
separated from the ovary and weighed.
From the total weight of the spawned
and unspawned (collected from ovary)
eggs, the percentage of spawning was
calculated.
Frequency of spawning refers to
the number of times the same
spawners are allowed to spawn. In
this study, the same spawners were
allowed to spawn three times after
ablation by separating them after
each spawning. Five replicates were
maintained for each set of
experiments.
Result
On average, 76% of spawners
spawned for the first time in each
batch. There was a direct relationship
between percentage of hatching and
weight of spawners (r+ >0.9). In the
100.6 ± 4.57 g size group, the
percentage of hatching was 86.40 ±
2.16. In the other size groups viz.
125.35 ± 3.43 g, 150.62 ± 7.4 g,
200.45 ± 7.25 g, 225.56 ± 4.60 g and
250.22 ± 8.30 g there was an increase
in percentage of hatching in the order
of 88.36 ± 2.36, 89.25 ± 3.40, 90.25 ±
2.21, 91.5 ± 3.41 and 93.75 ± 3.38,
respectively. But the size of spawners
had no effect on the start of hatching
(r=0.3).
Size of spawners was observed to
play a major role in the fecundity of
individuals. Fecundity increased with
increase in size of animals from 416  050
in size group of 100.43 g to 703 110
in size group of 225.8 g. (Fig. 1)
Increase in the percentage of egg
clumping resulted in a decrease in
the hatching percentage and also
delayed the start of hatching (Table
1). As clumping percentage
increased from 0 to 81.65, the start
of hatching time also increased from
14.40 ± 0.30 to 18.0 ± 1.54 hrs.
When the clumping percentage
Table 2. Rate of spawning in relation to success of spawning.
Spawning (%) Start of hatching (hrs) Hatching (%)
21.75 ± 3.00 14.50 ± 0.53 63.4 ± 2.7
40.50 ± 2.08 15.30 ± 0.43 77.8 ± 3.4
60.54 ± 2.64 14.50 ± 0.34 90.6 ± 2.9
79.59 ± 2.08 14.30 ± 0.52 92.3 ± 1.8
97.20 ± 1.81 14.40 ± 0.45 95.2 ± 2.1
Table 1. Influence of clumping of eggs on spawning in P. monodon.
% of clumping Start of Hatching (hrs) % Hatching
0 14.40 ± 0.30 92.6 ± 2.4
21.36 ± 1.26 15.10 ± 1.50 64.7 ± 2.6
40.50 ± 1.29 15.50 ± 1.20 30.8 ± 4.7
60.37 ± 1.40 17.10 ± 1.35 22.6 ± 3.6
81.65 ± 1.82 18.00 ± 1.54 8.5 ± 6.8
Table 3. Frequency of spawning related with % hatching and start of hatching.
Frequency of spawning Start of hatching (hrs) Hatching (%)
First spawning 14.20 ± 0.45 95.4 ± 3.6
Second spawning 15.40 ± 0.32 84.7 ± 4.1
Third spawning 15.50 ± 0.50 76.8 ± 6.8
Fig. 1. Relationship between weight of P. monodon spawner and fecundity.
750
700
650
600
550
500
450
400
350
300
0
100.43 125.64 150.76 175.66 200.48 225.84
N
O
. 
O
F
 E
G
G
S
WEIGHT OF SPAWNER (g)
15Naga, The ICLARM Quarterly (Vol. 24, Nos. 1 & 2) January-June 2001
increased to 81.65% from 0%, the
percentage of hatching decreased to
8.50 ± 6.86% from 92.6 ± 2.4 %.
When the percentage of
spawning decreased from 97.20 ±
1.81 to 21.75 ± 3.00, the hatching
percentage also decreased to 63.4 ±
2.7 from 95.2 ± 2.10 but there was
no remarkable change in the start of
hatching; it fluctuated between 14.30
and 15.30 hrs (Table 2).
A positive relationship was
observed between frequency of
spawning and start of hatching and
percentage hatching (Table 3). In the
first spawning, hatching started at
14.20 ± 0.45 hrs and the hatching
percentage was 95.40 ± 3.6. In the
second spawning, the start of hatching
and hatching percentage were 15.40
± 0.32 hrs and 84.7 ± 4.1%
respectively. In the third spawning,
the start of hatching was 15.50 ± 0.50
hrs and the percentage of hatching was
76.8 ± 6.8% (Table 3).
Discussion
Variations in reproductive quality
of shrimp brood stock have been
reported to be primarily genetic in
nature (Coyama et al. 1991). But the
present study shows that some factors
like spawner size, amount of clumping
of eggs, types of spawning and
frequency of spawning also influence
spawning success by changes in
hatching rate and start of hatching.
Motoh (1981) established a positive
correlation between fecundity and
female size in terms of carapace length
and Villegas et al. (1986) demonstrated
a positive correlation between
fecundity and spawner weight. The
present study also showed a positive
relation between the weight of
spawners and hatching percentage.
But no relationship was observed
between the size of spawner and start
of hatching.
Primavera (1982) working with
ablated females of P. monodon found
that the rematuration rate decreased
from 23.2 to 5.9% in the second and
third spawnings respectively. The
present study showed a decreased
hatching rate from the first spawning
to the third spawning (Table 3). This
may be due to the decrease in fatty
acid profile of  the ovary from the
first spawning to the subsequent
spawning (Marte 1982).
Clumping or aborted spawning
which occurs frequently during the
spawning of P. monodon also affected
spawning success. Some workers
have opined that it is due to the lack
of sufficient aeration during
spawning. But observation during the
present experiment substantiates that
it is due to the inherent reproductive
failure in spawning and stress. The
rate of clumping was higher when the
animal was under stress or when a
white necrotic spot appeared in the
matured ovary due to microsporidial
attack (Babu and Marian 1998).
In this study, it was observed that
two types of spawning take place in
P. monodon, i.e. full spawning and
partial spawning. Partial spawning
has been shown to be stress induced
during transport of spawners to the
hatchery (Babu and Marian 1998).
Stress increases cortisol release and
decreases the secretion of ovarian
ascorbic acid. This induces the
animal to spawn partially. The
reduced hatching rate with
successive spawning could be
attributed to reduced availability of
body reserves and lower deposition
of spermatophore in the helical
receptacle.
It is clear from the present study
that there is a need for an in-depth
study of the problem of clumping of
eggs, partial spawning and
increasing the spawning success
with repeated spawnings.
It is also clear that to run a
hatchery profitably,  special attention
must be paid to: the selection of
bigger size spawner; spawners with
empty space in the ovary must be
avoided; stress free transport must be
ensured; and frequent use of the same
spawners must be avoided.
References
Babu. M.M. and M.P. Marian.1998. Live
transport of gravid Penaeus indicus using
Coconut Mesocarp dust. Aquacultural
Engineering. 18: 149 – 155.
Coyama. R., C. Deupree, M. Chang, and
Edralin. 1991. Chapter 2. The biology
of Penaeus vannamei, p. 33-37. In
Wyban A.and J.N. Sweeney. Intensive
shrimp production Technology. The
Oceanic Institute shrimp manual.
Marte. 1982. Seasonal variation in food and
feeding of Penaeus monodon Fabricius
(Decapoda : natantia) Crustaceana 42:
250 – 255.
Motoh, H. 1981. Studies on the fisheries
biology of the giant tiger shrimp Penaeus
monodon in the Philippines. Tech. Rep.
No. 7. Aquaculture Department,
SEAFDEC., Philippines 128 p.
Primavera, J.H. 1982. Studies on brood stock
of Sugpo Penaeus monodon Fabricius
and other penaeid at the SEAFDEC
Aquaculture Department. Proceedings
of the symposium on coastal
aquaculture, 12-18 January 1980,
Cochin, India. Marine Biological
Association of India 1: 28 – 36.
Villegas, C.T., A, Trino and R. Travina. 1986.
Spawner size and the biological
components of the reproduction process in
Penaeus monodon Fabricius, p. 701-701.
In Maclean, J.L. and L.V. Hosillos (eds.)
Proceedings of the First Asian Fisheries
Forum, 26-31 May 1986, Manila,
Philippines. Asian Fisheries Society.
__________________
M. Babu, M.R. Kitto, C. Ravi and M.P.
Marian are from the Institute for Coastal
Area Studies, Manonmaniam Sundaranar
University Research Centre, Scott Christian
College Campus, Nagercoil, Tamil Nadu,
India. Corresponding address: Trisea
Shrimp Hatchery, Tiruchendur Marine
Drive, Chettikulam – 627 124, Tirunelveli
District, Tamil Nadu, India.
a
q
u
a
b
y
t
e


Factors determining spawning success in Penaeus monodon Fabricius

http://aquaticcommons.org/9071/1/aquabyte%202.pdf

Factors determining spawning success in Penaeus monodon Fabricius

Abstract

Similar works

Full text

Available Versions

Aquatic Commons