Broodstock development of giant grouper
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Broodstock development of giant grouper, Epinephelus lanceolatus.
Vichai Vatanakul, Janjit Kongkumnerd, Sunit Rojanapitayakul, Renu Yashiro and Poonsin
Panichasuke
NICA*, Songkhla
(Translated by Mr Hassanai Kongkeo)
Abstract
Broodstock development of giant grouper was conducted in net cages (5.0x5.0x3.0
m3) at Nu Island, Songkhla. Giant groupers (258.30±111.00 gm and 4,410.00±90.00
gm) were stocked at the density of 3 and 1.5 fish/m2 respectively. Fish were cultured
for 4 years and fed with trashfish. The result showed that growth rate of the 1st, 2nd,
3rd and 4th years were 500.99–646.00; 456.67–674.50; 650.00–694.16; and 507.50–
588.57 gm/month respectively. The 3rd year of the experiment, sperm milt could be
observed when stripped at the abdominal part of male. In the 4th year, eggs and sperm
could be observed. The first successful positive spawning response of the giant
grouper by HCG and Puberogen injection. The result indicated that giant grouper can
be cultured in net cages for broodstock development. Water quality parameters during
cultivation period were pH: 7.17-8.43, salinity: 0-34 ppt, alkalinity: 52-220 ppm while
nitrate, nitrite, ammonia-N and total P were 0-0.277, 0-0.048, 0-0.0237 and 0.0010.468 ppm respectively.
NICA*=National Institute of Coastal Aquaculture, Songkhla 90000, Thailand
Introduction
Giant grouper Epinephelus lanceolatus is the largest grouper which can be found in
both Andaman Sea and Gulf of Thailand, particularly in Phuket, Trang, Krabi, Satul,
Chantaburi, Trad and Cholburi Provinces (Boonliptanont P., 1997). Small size fish is
better taste and very expensive as it is the most favourable fish among Chinese. It can
be found in estuaries, mangrove areas and river mouths. There is world wide
geographic distribution of this fish such as East Africa, Red Sea, Pakistan, south
China, south Japan, Hawaii, Australia and Fitkalin Island (Heemstra and Randall,
1993). There has been giant grouper culture in Thailand but it was not expanded due to
limited amount of wild fries. Most of giant grouper production are by product from
cage culture of other grouper as it is difficult to identify the species of wild grouper
fingerlings. In order to promote new economic fish for marine aquaculture, giant
grouper has been selected as a promising species due to its fast growth rate. The
cultured giant grouper can reach 1.0 kg within 4 month (Boonliptanont P., 1997).
Many shrimp farmers would like to have alternate species due to the decrease in
Broodstock development of giant grouper
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shrimp production mainly caused by environment and pond deterioration. Giant
grouper is one of the required species by these farmers as it can yield very good price
and high demand in international markets. Therefore the Coastal Aquaculture Division,
Department of Fisheries initiated the broodstock development programme for further
fingerling production in order to promote giant grouper culture in the future.
Materials and methods
Giant groupers were collected from commercial net cages in Trang Province
(285.30±111.58 gm body weight and 26.12±3.31 cm length in average) and Phang-nga
Province (4,410±90.00 gm body weight and 60.35±4.38 cm length).They were
separately cultured in net cages (5.0x5.0x3.0 m3) with stocking densities of 3 and 1.5
fish/m2 respectively.
Net cages: 5.0x5.0x3.5 m3 cages were built in 20.0x20.0 m2 raft supported by
polyfoam blocks. Sizes of polyethylene nets for small and large fish were 1.5 and 3.5
inches respectively.
Feeding: Once a day, fish were gradually fed until fish stopped feeding by fresh
sardines which were chopped according to the sizes of fish mouths.
Data collection:
1. Growth rates were recorded by measuring total length and body weight monthly
from sampled 10-20 fish.
2. Gonad developments were studied from sampled fish by measuring body weight,
body length and gonad weight. Gonad tissues were preserved in Bouins fixative
for further study on gonad development using Yamamoto, 1956 method.
3. Mature eggs were checked by inserting a plastic tube of 2 mm diameter into
oviduct and sampling some eggs (generally over 0.42 mm size). Male
broodstock were considered matured if they released white milt after gently
pressed on their abdomens. Spawning was induced by hormone injection.
Broodstock were initially injected by HCG at the rates of 150 and 500 IU/Kg
B.W. and followed by Puberogen hormone at the rates of 100, 200 and 300
IU/Kg B.W. respectively.
Data analysis: Data were analysed by SPSS programme which was translated into
Thai by Ngamsantiwong T., 1995.
Results
1. Growth rates, food conversion ratios and survival rates of giant grouper broodstock
cultured in net cages at NICA substation, Nu Island were observed. In Figure 1, the
Broodstock development of giant grouper
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average growth rates in 1st, 2nd, 3rd and 4th years were 500.99-646.00; 456.67-674.50;
650.00-694.16 and 507.50-588.57 gm/month respectively. The final weight and length
at the end of experiment were averaged as 28.27-28.31 Kg and 109.16 cm
respectively. In Table 1, the increases in body weight and length were 15.91-19.46
gm/day and 0.035-0.058 cm/day respectively. Specific growth rate for body weight
was 0.15-0.37% per day and for body length was 0.07-0.11% per day. Average food
conversion ratio and survival rate were 3.85-4.09:1 and 24-84.44% respectively.
(A)
(B)
Fig. I Weight gain of giant grouper culture in net cage with stocking density 3/m3 (A)
and 1.5/m2 (B)
Table I Results of growth rate, Food conversion rate ratio and Survival rate of giant
grouper cultured in net cages.
Net
cage
Year
I
II
nd
I
2
II
rd
I
3
II
th
I
4
II
Average I
II
1st
No.
Weight gain
Specific growth
rate (%/day)
g./month cm./month Weight
500.99
646.0
674.50
456.67
694.16
650.0
507.50
588.57
594.29
585.31
3.11
2.20
1.83
0.84
1.48
1.01
0.50
0.14
1.73
1.05
0.97
0.30
0.25
0.11
0.13
0.11
0.13
0.07
0.37
0.15
Length
0.30
0.10
0.08
0.04
0.05
0.03
0.02
0.11
0.11
0.07
Food
Conversion
rate
3.94
3.78
3.29
3.97
4.26
4.63
3.89
3.96
3.85
4.09
Survival
Rate
(%)
58.66
91.11
55.26
88.88
30.00
86.67
24.00
84.44
Broodstock development of giant grouper
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2. Gonad tissues were observed from sampled broodstock for gonad development. It
was found out that ovary development in the third year was in the tertiary growth
phase with average body weight of 20.08 Kg and average GSI of 1.04 (0.664-1.47).
3. The results from first injection with HCG 150 and 500 IU/Kg B.W. and followed by
injection of Puberogen at the rates of 100, 200 and 300 IU/Kg B.W. respectively were
11 females spawned and 164,550 larvae developed (Table 2).
Table II Number of eggs spawned, Ferlilization rate and hatching rate
Date
Hormone
Number Eggs spawned
(x 103)
%
%
Fertilization Hatching
Larvae
1,021
62.0
9.99
102,150
11/10/1998 Puberogen
400
22.6
0.0
0
11/10/1998 Puberogen
1,001
9.9
0.0
0
11/10/1998 HCG
1,021
61.8
6.1
62,400
12/10/1998 Puberogen
802
12.9
0.0
0
13/10/1998 Puberogen
621
8.9
0.0
0
14/10/1998 HCG
120
0
0.0
0
HCG
1,620
0
0.0
0
21/11/1998 HCG
1,744
0
0.0
0
21/10/1998 HCG
640
0
0.0
0
21/10/1998 HCG
Average
121
0
0.0
828.3
16.1
1.45
0
Total
164,550
10/10/1998 HCG
9/11/1998
4. Water quality parameters during experiment were as follows:
pH
salinity
alkalinity
nitrite-N
= 7.17-8.43
= 0-34 ppt
= 52-220 ppm
= 0-0.048 ppm
Broodstock development of giant grouper
nitrate-N
ammonia-N
phosphorus
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= 0-0.277 ppm
= 0-0.237 ppm
= 0.001-0.468 ppm
Conclusion and discussion
It is possible to culture giant grouper broodstock in netcages until they spawn. At the
end of 4-year experiment, average body weight was 28.27-28.31 Kg with weight
increase at the rate of 19.51-22.76 gm/day and length increase at the rate of 0.0350.058 cm/day. The average specific growth rates for body length and weight were
0.046-0.0993% per day and 0.144-0.32% per day respectively. It can be concluded
that giant grouper is the fastest growing species in comparision with the body weight
increase at the rate of 2.3-2.9 gm/day in other grouper (Sakares W. and P. Kampang,
1987). Feeding by fresh sardines, food conversion ratios in giant grouper ranged from
3.29:1 to 4.26:1 which were close to the study of Boonliptanont P., 1997 (3.72:1).
However, its FCR is still lower than estuarine grouper (6.78:1) which was studied by
Sakares W. and P. Kampang, 1987. Survival rate in one experiment was unfortunately
poor due to grouper diseases spread from nearby grouper cages. In another
experiment, survival rate was high because fish were stocked after disease spread. For
gonad development in giant grouper, males became mature at the average weight of
17.585±2.681 Kg and at the average length of 97.971±11.0981 cm. Mature eggs were
observed when the average body weight and length of females were 25.03±6.4 Kg and
102.64±12.86 cm respectively. It was found out by Boonliptanont P, 1997 that gonad
development in giant grouper started when fish reached 2.5 Kg weight and the smallest
female with mature eggs was 15.21 Kg in size. In his experiment, the average body
weight of females with mature eggs which could be detected during breeding season,
was 22.08 Kg.
It was found out that the smallest size of eggs suitable for induced breeding by
hormone injection (HCG:150 and 500 IU/Kg B.W. and followed by Puberogen: 100,
200 and 300 IU/Kg B.W. with 24 hours interval) was 0.42 mm. As 164,550 larvae
have been produced in the first success in artificial breeding of giant grouper, it can be
shown that its broodstock can be artificially developed by netcage culture.
References
Ngamsantiwong Tawatchai, 1995. SPSS/PC+SPSS for Windows: Principles and
methods for the use of computer in statistics for research, Information Division,
Office for Technology Development, King Mongkut Institute of Technology,
North Bangkok Campus, 301-357.
Boonliptanont Paiboon, 1997. Some biological study of Epinephelus lanceolatus
(Bloch), Scientific Paper No. 2/1997, Coastal Aquaculture Division, DOF, 19
Broodstock development of giant grouper
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pp.
Sakares Wichien and Pornchai Kampang, 1987. Effect of stocking densities on the
growth and production of grouper in netcages, Scientific Paper No. 3/1987,
Rayong Coastal Aquaculture Station, Coastal Aquaculture Division, DOF, 24
pp.
Heemstra, P.C. and J.E Randall, 1993. FAO Species catalogue Vol.16: Grouper of the
world, FAO Fisheries Synopsis No. 125, Vol 16, FAO Rome, 172-175
Yamamoto, K. 1956. Studies on the formation of fish eggs: 1. Animal cycle in the
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Zool., Hokkaido Univ, 12:362-373.