Abu Al Abyad island is characterized by harsh environmental conditions. A preliminary trial conducted at the island to investigate the spawning and hatching performance of the blue finned sea bream Sparidentex hasta indicated that the fish can be successfully bred at high salinity levels exceeding 50 ppt.Salinity tolerance, Spawning, Hatching, United Arab Emirates, Sparidentex hasta

Ali, A.A.

Kumar, K.K.

Yousif, O.M.

English

Research Papers in Economics

13 NAGA, WorldFish Center Quarterly  Vol. 26 No. 4 Oct-Dec 2003
articles
Spawning and hatching performance of the 
Silvery Black Porgy Sparidentex hasta 
under Hypersaline conditions
O.M. Yousif, A.A. Ali and K.K. Kumar
Abstract
Abu Al Abyad island is characterized by harsh environmental conditions. A preliminary trial conducted at the 
island to investigate the spawning and hatching performance of the blue ﬁ  nned sea bream Sparidentex hasta 
indicated that the ﬁ  sh can be successfully bred at high salinity levels exceeding 50 ppt.
Introduction
The silvery black porgy or blue ﬁ  nned sea 
bream Sparidentex hasta, known as subaiti 
in the United Arab Emirates, is native to 
the Arabian Gulf, western Indian Ocean 
and coasts of India. It occurs in habitats 
varying from shallow (Fig. 1) coastal 
waters to deep water. The ﬁ  sh feeds 
mostly on invertebrates and crustaceans 
(Bauchot and Smith 1984; Kuronuma and 
Abe 1986;  Al-Abdessalaam 1995). 
The ﬁ  sh are protandrous hermaphrodites, 
that is, they possess both female and male 
gonadal tissue and mature ﬁ  rst as males, 
then become females as they get older 
(Parvez and Ahmed 2000). They are highly 
prized in the region. In the 1980s it was 
recognized that these ﬁ  sh possess 
characteristics desirable for aquaculture, 
such as readiness to spawn in captivity, 
rapid growth, and tolerance to a relatively 
wide range of culture conditions (Hussain 
et al. 1981). Hatchery technology for the 
commercial production of ﬁ  ngerlings of 
the species was established by the 
National Mariculture Center, Bahrain 
(Al-Ansari et al. 1998). 
The Abu Al Abyad island is situated west 
of Abu Dhabi and has low annual rainfall, 
high evaporation rates, high air tempera-
ture and high humidity. These factors have 
directly contributed to the unusually 
harsh marine conditions prevailing in the 
island. The island is characterized by its 
wide network of natural and artiﬁ  cially 
dredged channels that are fringed with a 
substantial expanse of mangrove trees 
(Avecinia marina) and shrubs.
The desirable characteristics for and the 
success achieved in culturing it have 
encouraged the introduction of this ﬁ  sh 
into Abu Al Abyad island.  The results of a 
preliminary trial undertaken in the Abu Al 
Abyad hatchery to assess whether this 
species can be spawned and hatched under 
hyper saline conditions, ranging between 
50 and 55 ppt, are presented in this paper.  
 
Fig. 1.  A 2.5 kg female Sparidentex hasta
Fig. 2.  Oval spawning tank with the egg 
collector placed at the overflow water exitNAGA, WorldFish Center Quarterly  Vol. 26 No. 4 Oct-Dec 2003 14
articles
Brood stock management
The hatchery bred ﬁ  ngerlings were reared 
to sexual maturity in 5x5x2.5 m ﬂ  oating 
net cages placed in one of the artiﬁ  cially 
dredged channels of the island. During the 
grow-out period the ﬁ  sh were fed to 
satiation with a combination of 52 per cent 
crude protein commercial pelleted feed 
and trash ﬁ  sh (sardines) enriched with ﬁ  sh 
oil (10 g/kg).  At the end of the ﬁ  rst year of 
rearing, the S. hasta ﬁ  ngerlings in the net 
cages reached a size of 500 g in weight and 
the whole population was observed to 
have matured as males with thick and 
glutinous ﬂ  owing milt.  At the end of the 
second year, the ﬁ  sh had an average weight 
of 1 kg and some of them were observed 
to have changed sex but had not attained 
complete maturity. In the third year, about 
10 per cent of the population was easily 
distinguishable as females. 
In mid-December 2000 when the ﬁ  sh 
were two years old, eighty males with an 
average weight of 1.9 kg (1.30 to 2.50 kg) 
and eighty females with an average weight 
of 2.1 kg (1.60 to 2.75 kg) were 
segregated into two net cages. Beginning 
early January 2002, females with swollen 
abdomens were selected, injected with 
HCG at 400 IU per kg body weight of ﬁ  sh 
and kept in a separate net cage.  After 24 
hours a resolving dose of 100 IU/kg body 
weight was administered to the females. 
Immediately after the second injection, 
females and males with free ﬂ  owing milt 
were transferred to the hatchery where 
they were stocked for spawning, at a sex 
ratio of 1:1, in an oval 40 t concrete tank 
at a density of one ﬁ  sh/m3. Filtered 
seawater was continuously supplied at 40 
l/min, allowing a 200 per cent daily water 
exchange. Fish in the spawning tanks were 
fed squid meat at a rate of two per cent 
body weight. During the spawning season 
the water salinity was constant at 54 ppt 
and the average maximum and minimum 
water temperatures ranged between 18 
to 19 ºC and 22 to 23 ºC, respectively. In 
another identical tank, a second group of 
spawners was also stocked at a sex ratio 
of 1:1 and left to spawn naturally.  
 
Spawning and hatching
The induced ﬁ  sh were observed to spawn 
48 hrs after the second hormonal injection. 
The buoyant eggs were directed towards 
the overﬂ  ow opening by the gentle inlet 
water current. Pelagic eggs were collected 
twice daily (8:00 hrs and 17:00 hrs) in ﬁ  ne-
meshed 400µ collection buckets placed at 
the overﬂ  ow waters from the spawning 
tanks (Fig. 2). The eggs were then washed 
thoroughly with fresh seawater and placed 
in a measuring cylinder for separation of 
good buoyant fertilized eggs from sinking 
bad eggs as well as for volumetric 
estimates (Fig. 3). To ensure good water 
quality, about 50 per cent of the bottom 
water from the tank was drained out daily 
after the second egg collection in the 
afternoon through a drain exit located at 
the bottom of the tank.
 
Spawning period Lunar cycle
Collected eggs
       Total           good         bad
      (106)            (%)             (%)
Incubation period
(hrs)
Hatching rate
(%)
Water temp. (°C)
 max        min
8 - 13 Jan 2nd quarter       0.99          39.30          60.70 24 6.05   20         19
14 - 27 Jan 1st quarter       3.29          33.70          66.30 30 2.16   19         18
28 Jan - 12 Feb 2nd quarter       3.78          33.40          66.60 42 72.48   19         18
27 Feb - 13 Mar 2nd quarter      16.32          78.80            21.20  22 20.65   23         22
Table 1. Induced spawning and hatching rate of S. hasta in 40 t indoor concrete tanks
The total number of eggs collected from 
30 females during the whole spawning 
period (8 January-13 March) was 24.4 
million eggs at an average of 0.39 million 
eggs per one kilogram of female (Table 1).  
Each female spawned once during this 
period. The good ﬂ  oating eggs comprised 
64 per cent of the total number of eggs 
collected. Only buoyant eggs were 
stocked in 600 µ mesh incubators (70 cm 
in diameter and 65 cm in height) placed in 
5 t rectangular ﬁ  berglass tanks with ﬂ  ow-
through ﬁ  ltered and sterilized seawater. 
Eggs were stocked at an average rate of 
300 ml/incubator (approx. 600 000 eggs/ 
incubator). Dead eggs were continuously 
siphoned out from the bottom of the 
incubators.  The average hatching rate was 
only 23.17 per cent of the total incubated 
eggs. The incubation period ranged 
between 42 hrs (at a minimum water 
temperature of 18 ºC) and 23 hrs (at a 
maximum water temperature of 23 ºC).
In the control tank, the ﬁ  rst natural 
spawning occurred at the end of January 
and continued till the middle of March. 
The total number of eggs collected from 
30 females was 32.6 million eggs at an 
average of 0.52 million eggs per one 
kilogram of female.  About 81.41 per cent 
of this number were good eggs. The 
average hatching rate was only 27.87 per 
cent of the total incubated good eggs 
(Table 2).
For both the induced and naturally 
spawned groups, spawning was continuous 
at both the ﬁ  rst and second quarters of 
the moon, suggesting that spawning of this 
species is not synchronized with the lunar 
cycle. On the other hand, it was observed 
that ﬁ  sh spawning activity increased 
following the ﬂ  ushing out and sudden 
reﬁ  lling of the spawning tanks. This 
suggests that there is a correlation 
between spawning and tidal ﬂ  oods or 
currents. Further investigations are 
suggested to test the use of this natural 
trigger in initiating and controlling the 
Fig. 3. Separation and volumetric 
counting of eggs15 NAGA, WorldFish Center Quarterly  Vol. 26 No. 4 Oct-Dec 2003
articles
spawning activity of S. hasta. The 
incubation period was observed to 
increase with decreasing water 
temperature. Owing to limited hatching 
facilities, spawning activity was 
discontinued by the middle of March and 
the spawners were transferred back to 
their respective net cages.  
 
Conclusion
The husbandry procedures applied in this 
trial indicate that hormonal injections are 
unnecessary for spawning induction, 
especially when the water temperature is 
above 20 ºC, and ﬁ  sh can spawn naturally. 
The incorporation of polyunsaturated 
fatty acids in the brood stock feed 
improved to some extent the quality of 
the eggs as well as the hatching rate.
Hormonal treatment resulted in poorer 
egg quality and a lower hatching rate than 
Fig. 4. Newly hatched larvae collection from the 600 µ eggs incubators 
Spawning period Lunar cycle
Collected eggs
       Total           good         bad
      (106)            (%)             (%)
Incubation period
(hrs)
Hatching rate
(%)
Water temp. (°C)
 max        min
28 Jan - 12 Feb 2nd quarter     14.46           73.24         26.76 42 20.65   19         18
13 Feb - 26 Feb 1st quarter       3.16           68.35         31.65 30 51.06   21         20
27 Feb - 13 Mar 2nd quarter     14.98           92.05           7.95 22 29.78   23         22
Table 2. Natural spawning and hatching rate of S. hasta in 40 t indoor concrete tanks
natural spawning. However, the spawning 
performance obtained in this trial is 
considered low as compared to those 
reported from other parts of the region 
(Al-Ansari et al. 1998). The cause for this 
low performance is not speciﬁ  cally 
known but high salinity could be a factor. 
Towards the end of the spawning season, 
the total number of eggs produced, 
fertilization and hatchability increased 
compared to those obtained at the 
beginning of the season. This might be 
due either to lower water temperatures 
in January or to the immaturity of the 
eggs. These observations suggest that the 
proper spawning season for S. hasta in 
Abu Al Abyad island is between February 
and March. In general, these ﬁ  ndings 
indicate that the spawning and hatching 
of S. hasta is possible in the harsh 
environmental conditions of the island 
and plans for mass larvae production 
should be encouraged.
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______________________________
O.M. Yousif, A.A. Ali and K.K. Kumar 
are from the Fish and Shrimp Farming 
Project,  Abu Al Abyad, P.O. Box 372,  
Abu Dhabi, United Arab Emirates.
E-mail: onrash@emirates.net.ae

FAO species identification sheets for fishery purposes.

First observations on natural sex reversal in a protandrous bream (Sparidentex hasta: Sparidae) from Kuwait.

Marine species of the Sultanate of Oman. An Identification Guide.

Production of sobaity bream, Sparidentex hasta, larvae and fry at the

Spawning, egg and early larval development, and growth of Acanthopagrus cuvieri (Sparidae).

Spawning and hatching performance of the silvery black porgy Sparidentex hasta under hypersaline conditions

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Spawning and hatching performance of the silvery black porgy Sparidentex hasta under hypersaline conditions

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