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Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
132
Protocol development for the improved hatchery
4892
propagation of Tiger grouper Epinephelus fuscoguttatus
4893
(Forsskål, 1775) in Palawan, Philippines
4894
4895
Elmer G. Villanueva1*, Kyra Hoevenaars2, Jonah van Beijnen2,3,
4896
Al P. Gonzales3,4, Roger G. Dolorosa1 and Lota A. Creencia1
4897
1Western Philippines University, Puerto Princesa City 5300, Palawan, Philippines
4898
2Fins and Leaves, Oude Bennekomseweg 23, 6706 ER Wageningen, the Netherlands
4899
3Center for Sustainability, Puerto Princesa City 5300, Palawan, Philippines
4900
4Aqua Bridge Farms Company, Kingdom of Saudi Arabia
4901
*Correspondence: elmer.villanueva@rocketmail.com
4902
4903
ABSTRACT
4904
4905
The expanding grouper cage farming in Palawan,
4906
Philippines requires stable seed supplies from hatcheries to
4907
sustain the demands of fish cage operators. To improve the
4908
current hatchery practices for Tiger grouper Epinephelus
4909
fuscoguttatus (Forsskål, 1775), four experiments were
4910
undertaken. The first experiment (E1), involving three different
4911
temperatures ranges (T1: 24-26oC; T2: 27-29oC; and T3: 30-32oC)
4912
revealed significantly higher hatching rates at 27-32°C. The
4913
second experiment (E2) found that survival rates after 38 days
4914
from hatching were inversely proportional with density (T1: 3; T2:
4915
5; and T3: 10 larvae L-1). The third experiment (E3) found that the
4916
growth and survival of fry raised at three different stocking
4917
densities for three weeks (from 21 to 42 days after hatching) were
4918
not significantly different. The fourth experiment (E4) compared
4919
the growth and survival of fingerlings (from 70 – 91 days after
4920
hatching) fed with two brands of commercial feeds. After three
4921
weeks, both treatments had comparable total lengths. These
4922
desirable results are attributed to the weekly thinning or
4923
reduction in the density of juveniles in E3 and E4 and the use of
4924
small rearing containers.
4925
4926
Keywords: aquaculture, hatchery production, survival, growth,
4927
diet, stocking density, hatching rate.
4928
4929
4930
INTRODUCTION
4931
4932
In Southeast Asia, the main target reef species are groupers (subfamily
4933
Epinephelinae), which are mainly destined for international live reef-fish
4934
trade. The large demand and high price for groupers have led to severe
4935
overfishing. Even more worryingly, to obtain their catch alive, fishers often
4936
employ cyanide to temporarily immobilize their catch (Wilcox 2016). The use
4937
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
133
of cyanide has a deleterious impact on the reef, including the health and
4938
productivity of other reef-dwelling organisms (Halim 2002).
4939
4940
To bring a halt to the overfishing and destruction of coral reefs across
4941
Southeast Asia, there is a need to provide alternative livelihoods to fishermen
4942
(Heeger et al. 2001). In addition, ensuring future food security and inclusive
4943
development in rural areas. The sustainable aquaculture of high-value marine
4944
finfish is often identified as a potential solution that meets these requirements
4945
(Haylor et al. 2003).
4946
4947
In Palawan, a local non-government organization (NGO) has been
4948
pioneering the hatchery production of different grouper species to support the
4949
livelihood of coastal inhabitants. To further refine its hatchery protocols, the
4950
organization teamed up with the Western Philippines University (WPU) to
4951
optimize the production and expand the volume and diversity of hatchery
4952
produced fingerlings.
4953
4954
One of the focal species for this joined research project was the Tiger
4955
grouper Epinephelus fuscoguttatus (Forsskål, 1775), locally known as
4956
“Lapulapu Baboy” or Kugtong Baboy”. This reef-dwelling species was selected
4957
because of its high demand in the local and international markets. This fish
4958
grows relatively fast reaching 500 g in nine to 10 months. However, this fast
4959
growth rate is accompanied by severe cannibalism, which can lower survival
4960
rates (SR). Therefore, improved hatchery and nursery protocols need to be
4961
established to support future grow-out culture in coastal areas. This paper
4962
included four studies which dealt with the following: 1) hatching rates (HR) at
4963
different temperatures, 2) larval SR at different stocking densities, 3) growth
4964
and survival of fry, and 4) growth and survival of fingerlings subjected to
4965
weekly reduction in densities.
4966
4967
4968
METHODS
4969
4970
Egg Collection
4971
4972
Eggs were collected from 15 E. fuscoguttatus breeders (each weighing
4973
15 to 20 kg) from floating sea cages (4 x 4 x 7 m) by the Bureau of Fisheries
4974
and Aquatic Resources (BFAR) – Inland Sea Ranching Station for over 5 years
4975
along the Sta. Lucia cove of Puerto Princesa Bay. The upper half of the inner
4976
circumference of the cage holding the breeders (~20 individuals) were lined
4977
with fine-meshed net to retain any floating eggs inside the cage. The breeders
4978
were monitored between 2300 and 0100 hours on the night of new moon and
4979
up to three consecutive nights thereafter. When spawning occurred, eggs were
4980
collected with a fine meshed net 10 minutes after the main spawning activity
4981
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
134
to ensure proper fertilization. Eggs were then transported from the broodstock
4982
cage to the land-based hatchery using 10-L buckets with gentle aeration.
4983
4984
Egg Cleaning and Incubation
4985
4986
Newly collected eggs were first rinsed with fresh seawater to remove
4987
algae and other foreign materials. After this, the eggs were rinsed in water with
4988
an iodine solution for 1 min. Viable floating eggs were separated from the non-
4989
viable suspended eggs. Then the eggs were incubated in conical 50-L
4990
incubators with an upwelling flow-through system. Eggs typically hatched
4991
between 24 to 28 hours after spawning. Undeveloped eggs and other debris
4992
which sank at the bottom of the tanks were regularly removed by opening the
4993
bottom drain valve of the conical tank. The produced larvae were used in E2,
4994
E3 and E4, respectively.
4995
4996
Experiment 1 (E1): Hatching rates of E. fuscoguttatus Eggs at
4997
Different Temperature Regimes
4998
4999
In this experiment the HR at three temperature regimes (3
5000
replications), T1: 24-26oC; T2: 27-29oC; and T3: 30-32oC were evaluated for a
5001
24-hour period in nine 15-L capacity cylindrical plastic containers. For each
5002
treatment-replicate, 12,000 newly collected eggs were stocked in each
5003
cylindrical container (Table 1). Seawater ice (in double-layered plastic bags)
5004
and water heaters were used to maintain the desired temperature ranges. The
5005
temperature was monitored every five hours, and additional ice were added
5006
when necessary. After 24 hours, subsamples from each treatment-replicate
5007
were taken to determine the ratio between larvae and un-hatched eggs.
5008
5009
Table 1. Density of tiger grouper Epinephelus fuscoguttatus eggs subjected to
5010
different temperature ranges for 24 h. T-treatment; R-replicate.
5011
5012
T
R
Temperature
Range (oC)
Duration (h)
Egg
Density/Container
Water
Volume (L)
1
3
24-26
24
12,000
15
2
27-29
3
30-32
5013
Experiment 2 (E2): Larval Rearing of E. fuscoguttatus at Different
5014
Stocking Densities
5015
5016
For this experiment the SR of newly hatched fry was monitored at
5017
three different stocking densities (individuals per liter or ind L-1) or treatments
5018
(T1: 3 ind L-1; T2: 5 ind L-1; and T3: 10 ind L-1) with three replications. This was
5019
carried out for 38 days (from the first day after hatching or DAH) in nine
5020
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
135
5,000-L capacity concrete tanks (Table 2). The larvae were fed with a
5021
combination of rotifer, Artemia and imported commercial grouper feeds.
5022
5023
Table 2. Density of tiger grouper Epinephelus fuscoguttatus larvae at different
5024
stocking densities fed with a combination of rotifer, Artemia and commercial
5025
feed. T-treatment; R-replicate.
5026
5027
5028
The first feeding in E2 occurred on the 3rd DAH when the mouth of the
5029
larvae was large enough to consume rotifers (L type). The rotifer density in the
5030
larval rearing tanks was monitored twice a day (0700 and 1500 h) to maintain
5031
the desired number and size until the 25th DAH. On the 12th DAH, a pinch of
5032
artificial pellet was introduced every hour between 0600 and 1700. Artemia
5033
were added two times daily (0700 and 1500 h) between 12 DAH and 30 DAH,
5034
starting with newly hatched Artemia. As the grouper larvae increase in size,
5035
larger Artemia were fed. Artemia were enriched with vitamins for 4 h before
5036
feeding to the larvae. Water temperature, salinity, pH and ammonia were
5037
monitored in the morning (0800 h) and afternoon (1500 h).
5038
5039
Experiment 3 (E3): Growth and survival of E. fuscoguttatus Fry at
5040
Different Stocking Densities Fed with Commercial Feed
5041
5042
The experiment was carried out for three weeks in 15 plastic 25-L
5043
capacity blue basins to monitor growth and survival for 42-day old juveniles at
5044
different stocking densities. Three different stocking densities (treatments)
5045
5046
Table 3. Weekly density of tiger grouper Epinephelus fuscoguttatus juvenile
5047
at different treatments fed with commercial feed raised in small basin (25-L)
5048
for 21 days. T-treatments; R-replicates; W-week; DAH-days after hatching.
5049
5050
T
R
Feeding
Density
(ind L-1)
Number per
Basin
Starting
Age
(DAH)
Water
Volume
per Basin
(L)
W1
W2
W3
W1
W2
W3
1
5
ad libitum, 3-5
min every hour
from 0700 - 1800
6
4
2
150
100
50
42
25
2
12
8
4
300
200
100
3
18
12
6
450
300
150
5051
T
R
Feeding
Density
(ind L -1)
Density/Tank
Duration
(day)
Tank
Volume (L)
1
3
rotifer,
Artemia,
commercial
feed
3
15,000
38
5,000
2
5
25,000
3
10
50,000
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
136
were reduced each week for a period of three weeks by manually removing the
5052
largest and the smallest individuals (Table 3). Each treatment was replicated
5053
five times. The juveniles having the following initial average total length (TL):
5054
2.66±0.34 cm (T1); 2.99±0.40 cm (T2); and 2.89±0.60 cm (T3) were fed ad
5055
libitum throughout the day using imported commercial grouper feed. Wastes
5056
that settled on the bottom of the basin were siphoned 2-3 times a day.
5057
5058
Experiment 4 (E4): Growth and Survival of E. fuscoguttatus
5059
Fingerlings Subjected to Weekly Reduction of Densities and Fed
5060
with Two Different Commercial Diets
5061
5062
This experiment monitored the growth and survival of fingerlings fed
5063
with two different commercial diets: an imported (T1) and a locally
5064
manufactured pelleted feed (T2). The experiment with nine replications was
5065
carried out in 18 plastic 25-L blue basins. To maintain uniform size and prevent
5066
the occurrence of cannibalism, the densities were manually reduced on a weekly
5067
basis (Table 4). The 70-day old fingerlings initially measured 6.07±0.70 cm (T1)
5068
and 6.17±0.70 cm (T2), respectively. The fingerlings were fed ad libitum
5069
throughout the day. The treatments received continuous water exchange at 2 -
5070
4 L hr-1 and gentle aeration. Waste was siphoned 2-3 times daily.
5071
5072
Table 4. Weekly density of tiger grouper Epinephelus fuscoguttatus
5073
fingerlings fed with two commercial feed. T-treatment; R-replicates.
5074
5075
T
R
Feeding
Feed
Pellet
Density
(ind L -1)
Actual
Number/Basin
Starting
Age
(DAH)
Water
Volume
per
Basin (L)
W1
W2
W3
W1
W2
W3
1
9
ad libitum, 3-
5 min every
hour from
0700 - 1800
Imported
4
3
2
100
75
50
70
25
2
Local
5076
Data Analyses
5077
5078
The HR in E1, the SR in E2, E3 and E4, and the growth rates in E4 were
5079
all compared separately using analysis of variance and Scheffe post hoc tests.
5080
The TL and SR in E4 were compared using T-test. All analyses were performed
5081
at 5% significance level using SPSS 19.0 trial version.
5082
5083
5084
5085
5086
5087
5088
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
137
RESULTS
5089
5090
Experiment 1 (E1): Hatching Rates of E. fuscoguttatus Eggs at
5091
Different Temperature Regimes
5092
5093
Treatment 3 had the highest HR (80.32±8.37%) although it was not
5094
significantly different (P>0.05) from T2 (75.43±10.64%). The HR
5095
(54.66±23.87%) in T1 was significantly lower (P<0.05) compared to the other
5096
treatments (Figure 1).
5097
5098
5099
5100
5101
Figure 1. Average (±SD) hatching rates of Epinephelus fuscogutatus eggs at
5102
three temperature regimes (T1: 24-26oC; T2: 27-29oC; and T3: 30-32oC).
5103
5104
Experiment 2 (E2): Survival of E. fuscoguttatus at Different
5105
Stocking Densities
5106
5107
The SR was inversely proportional to density (Figure 2) and was
5108
significantly different (P<0.05) among treatments. The average (±SD) SR in
5109
T1 (6.86 ±0.54%) was significantly higher than in T3 (1.33±1.42%) but not in
5110
5111
5112
5113
Figure 2. Average (±SD) survival of Epinephelus fuscoguttatus fry at three
5114
different stocking densities (T1: 3 ind L-1; T2: 5 ind L-1; T3: 10 ind L-1) raised
5115
in concrete tanks from day 1 to 38 days after hatching.
5116
0
2
4
6
8
T1 T2 T3
Percentage (%)
b
ab
a
0
25
50
75
100
T1 T2 T3
% Hatching Rate
b a a
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
138
T2 (4.26 ±1.32%). At the end of the rearing period, the fry measured 20.7 (±
5117
0.52) mm, an average 18.7 mm TL increment. The range of average water
5118
temperature: 28.37oC (±0.58) to 28.71oC (±0.51); salinity: 26.14 (±0.63) to
5119
26.29 (±0.70) ppt; pH: 8.50 (±0.18) to 8.67 (±0.19); and ammonia: 0.43
5120
(±0.16) to 0.45 (±0.15) did not significantly differ among treatments.
5121
5122
Experiment 3 (E3): Growth and Survival of E. fuscoguttatus Fry at
5123
Different Stocking Densities fed with Commercial Feed
5124
5125
The weekly increase in TL was about 1 cm for all treatments. In week
5126
1, the average (±SD) final TL in T2 (4.03±0.54 cm) was significantly bigger
5127
than the other two treatments (Table 5). The SR (Table 6) for the first week
5128
were significantly different than the second and third weeks (P<0.05).
5129
However, SR among treatments were not significantly different (P>0.05).
5130
5131
Table 5. Initial and final total length (cm) of Epinephelus fuscogutatus at
5132
different stocking densities. The same letter superscript (per column) means
5133
not significant at 5%. n-number of measured samples per treatment; TL-total
5134
length; w–week.
5135
5136
Treatment
Weekly Average (±SD) Total Lengths (cm)
W1
W2
W3
Initial TL
(cm)
Final TL
(cm)
Initial TL
(cm)
Final TL
(cm)
Initial TL
(cm)
Final TL
(cm)
1 (n=50)
2.65a
(±0.34)
3.70a
(±0.49)
4.39a
(±0.35)
5.38a
(±0.37)
5.86a
(±0.24)
6.94a
(±0.30)
2 (n=50)
2.98b
(±0.40)
4.03b
(±0.54)
4.35a
(±0.41)
5.33a
(±0.38)
5.84a
(±0.31)
6.92a
(±0.34)
3 (n=50)
2.89b
(±0.60)
3.64a
(±0.44)
4.33a
(±0.45)
5.22a
(±0.42)
5.92a
(±0.32)
6.92a
(±0.42)
5137
5138
Table 6. Weekly survival rates (%) of Epinephelus fuscogutatus at different
5139
stocking densities. T-treatment; w-week.
5140
5141
T
Weekly Survival Rates (%)
W1
W2
W3
1
95.73
99.20
100.00
2
94.47
99.40
99.20
3
94.84
98.73
99.73
5142
5143
5144
5145
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
139
Experiment 4 (E4): Growth and Survival of E. fuscoguttatus
5146
Fingerlings Fed with Different Commercial Feeds
5147
5148
The weekly increase in TL was less than 1 cm for both treatments.
5149
Those fed with imported commercial feed (T1) were larger on the third week
5150
and were significantly different (P<0.05) to the other treatment (Table 7).
5151
Survival rates (Table 8) varied between 91.67% and 99.78% and were not
5152
significantly different between treatments (P>0.05).
5153
5154
Table 7. Initial and final average (±sd) total lengths (cm) of juvenile
5155
Epinephelus fuscoguttatus fed with two brands of commercial grouper feed.
5156
T-treatment; n-number of samples; w-week. TL-total length.
5157
5158
T
Weekly Average (±sd) Total Lengths (cm)
W1
W2
W3
Initial TL
(cm)
Final TL
(cm)
Initial TL
(cm)
Final TL
(cm)
Initial TL
(cm)
Final TL
(cm)
1 (n=90)
6.07
(±0.70)
6.69
(±0.65)
7.03
(±0.72)
7.47
(±0.66)
7.67
(±0.47)
8.51
(±0.61)
2 (n=90)
6.17
(±0.70)
6.62
(±0.63)
7.09
(±0.64)
7.41
(±0.69)
7.50
(±0.71)
8.04
(±0.53)
remarks
P>0.05
P>0.05
P>0.05
P>0.05
P>0.05
P<0.05
5159
Table 8. Survival rates of Epinephelus fuscoguttatus fed with two different
5160
commercial feed. w-week.
5161
5162
5163
DISCUSSION
5164
5165
Experiment 1 (E1): Hatching Rates of E. fuscoguttatus Eggs at
5166
Different Temperature Regimes
5167
5168
The average HR for E. fuscoguttatus in T2 (75.43%) and T3 (80.32%)
5169
were comparable to the following reported HR for other grouper species:
5170
83±10.12% for Epinephelus polyphekadion (James et al. 1997), 84.3% for
5171
Epinephelus akaara (Okumura et al. 2002), and 75.7% for E. malabaricus
5172
(Ruangpanit et al. 1993). The high HR in T3 and T2 showed a large
5173
temperature range (27oC and 32oC) for incubating E. fuscoguttatus eggs. This
5174
large range is comparable to that of E. coioides (Kawahara et al. 1997;
5175
Treatment
Weekly Survival (%)
W1
W2
W3
1
91.67
98.22
99.78
2
92.78
96.74
99.11
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
140
Fouroofghifard et al. 2012; Table 9). Ideal temperature for fertilization and
5176
hatching for other species may be narrow (28 and 30oC) as for the case of
5177
Heterobranchus bidorsalis (Okunsebor et al. 2015). The observed wide range
5178
for E. fuscoguttatus is therefore an advantage when breeding the species.
5179
5180
Table 9. The hatching rates of Epinephelus fuscoguttatus at three different
5181
temperature ranges compared with similar studies. T-treatment.
5182
5183
Species
T (oC)
Stocking
density/
Liter
Culture
System
Duration
(h)
Hatching
Rate (%)
Source
Epinephelus
fuscoguttatus
24-26
800
Cylindrical
plastic
containers
(15 L)
24
54.66
This study
27-29
75.43
30-32
80.32
Epinephelus
coioides
22
428.6
Beaker (7 L)
33
2.1 - 93.2
Kawahara et
al. 1997
24
87.2 - 96.5
26
86.4 - 98.3
28
85.1 - 98.2
30
67.3 - 93.8
32
45.7 - 84.8
34
1.2 - 9.6
Epinephelus
polyphekadion
29
300 – 500
Fiber glass
tanks (2,000
to 2,800 L)
19
83
James et al.
1997
Epinephelus
akaara
84.3
Okumura et
al. 2002
Epinephelus
malabaricus
28.15
1,500-1,600
Flow-
through
Pan-like
tanks
(30 L)
24
75.7
Ruangpanit et
al. 1993
Epinephelus
coioides
23 – 24
25
Polyethylene
tanks (300
L)
24
0
Fourooghifard
et al. 2012
26 -27
23
28-29
75
31-32
23
5184
Experiment 2 (E2): Larval Rearing of E. fuscoguttatus at Different
5185
Stocking Densities
5186
5187
Survival of grouper larvae up to metamorphosis is generally low across
5188
all species. James (et al. 1997) recorded a survival of 1.73% – 2.98% for E.
5189
polyphekadion. Survival for E. fuscoguttatus reported in Reyes (undated) was
5190
between 0.109% and 0.91%. In this study, the SR were inversely proportional
5191
with density. However, these SR (1.33%, 4.26% and 6.86%) in three
5192
treatments were higher compared to the 0.9% survival of E. fuscoguttatus
5193
raised at 30 ind L-1 for a period of 45 days (James et al. 1998; Table 10). This
5194
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
141
shows that density greatly affect the survival of E. fuscoguttatus fry, and is
5195
also reported for many other species such as Clarias gariepinus (Jamabo and
5196
Keremah 2009), Rachycentron canadum (Hitzfelder et al. 2006), and Soiea
5197
soiea (Schram et al. 2006). While lower stocking densities in indoor tanks may
5198
result in higher SR, this requires increased space and resources in hatcheries.
5199
However, the use of other culture facilities, such as outdoor concrete tanks for
5200
Epinephelus fuscoguttatus x lanceolatus at 8 ind L-1, had 26.9% survival
5201
(Anita and Dewi 2020). If available space permits, a trial on outdoor rearing
5202
of fry could be performed for E. fuscoguttatus to possibly increase SR.
5203
5204
Table 10. Average total lengths (TL) and survival rates (SR) of Epinephelus
5205
fuscoguttatus fry compared with other similar studies. T- treatments.
5206
5207
Species
T
Density
(ind L-1)
Duration
(day)
Mean
TL
(mm)
Feed
SR
(%)
Culture
System
Source
Epinephelus
fuscoguttatus
1
3
38
20.7
Natural/
commerci
al feed
6.86
Concrete tank
(5,000 L)
This
study
(E2)
2
5
2.26
3
10
1.33
Epinephelus
fuscoguttatus
1
30
45
34.40
Natural/
artificial
diet
0.9
Fiberglass
tank (2,800 L)
James
et al.
1998
Epinephelus
polyphekadion
2
19.77
1.7
Epinephelus
fuscoguttatus x
lanceolatus
1
8
30
28
Natural/
artificial
diet
26.9
Concrete
pond (10,000
L)
Anita
and
Dewi
2020
Epinephelus
fuscoguttatus
1
15
30
7.47 –
9.70
Rotifer/
Artemia
0.38 -
0.91
Concrete tank
(3,000 L)
Reyes
Undated
2
43
15.7–
17.39
0.109 –
0.115
Concrete tank
(5,000 L)
Epinephelus
polyphekadion
30
50
Natural/
artificial
feeds
1.7 – 2.98
Round
fiberglass
tank (2,800 L)
James
et al.
1997
5208
In commercial hatchery operations, it is not only the SR that is of
5209
importance, but also the overall performance of the hatchery (the combination
5210
of survival, and growth rate). The grouper in this study completed the
5211
development into juveniles and reached 20 mm average TL at 38 DAH. This
5212
is much faster than in the study of Sugama et al. (2012), where E.
5213
fuscoguttatus completely metamorphosed at 45 DAH (TL reached 20–28
5214
mm), and juvenile E. lanceolatus metamorphosed at 45 DAH at 35.4 mm TL
5215
(Garcia-Ortega et al. 2013). It could be noted however that Sugama et al.
5216
(2012) suggested a density of 10 ind L-1 which could attain 5 to 40% survival.
5217
These variations in larval development and survival could be related to water
5218
conditions and nutrition. The early occurrence of complete metamorphosis in
5219
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
142
this study could be attributed to the lower stocking densities which promoted
5220
faster growth. Reduced stocking density promotes good water conditions, and
5221
minimizes the chances of serranid larvae of becoming entangled with each
5222
other via their elongated dorsal and pelvic spines (Sugama et al. 2012).
5223
5224
Experiment 3 (E3): Growth and Survival of E. fuscoguttatus Fry at
5225
Different Stocking Densities fed with Commercial Feed
5226
5227
The results in this study were comparable to that of Salari et al. (2012)
5228
where stocking density did not significantly affect the survival of E.
5229
fuscoguttatus juveniles (Table 11). Severe cannibalism often occurs at this
5230
stage, but this was not observed even when the densities were much higher
5231
than the recommended density by Ismi et al. (2012).
5232
5233
The culture systems and stocking densities affect the growth
5234
performances, feed utilization and water quality (Samad et al. 2014). The
5235
rearing of fish at higher densities optimizes productivity of the facilities but
5236
increases the demand for dissolved oxygen, higher chances of cannibalism and
5237
disease outbreaks. However, the survival in this study (99.2 to 100%) are
5238
higher than the estimated 60% survival for E. fuscoguttatus upon reaching 7
5239
cm TL (Ismi et al. 2012). The weekly manual thinning which was carried out
5240
by removing the smallest and the largest individuals to reduce both the density
5241
and variations in sizes could have efficiently prevented cannibalism. Although
5242
frequent grading has been reported to cause stress which may lead to disease
5243
outbreak (Ismi et al. 2012), this did not occur during the experiment. The use
5244
of small basins and manual sorting could have facilitated efficient cleaning,
5245
water exchange, faster sorting, and reduced disturbance to the fish. The low
5246
mortality could have been caused by other factors, but this was not
5247
investigated due to limited laboratory facilities and equipment. Future studies
5248
may deal on these unknown aspects in the nursery rearing of this species.
5249
5250
In terms of growth, the fish reached 6.94 cm from an initial of 3.65 cm
5251
TL after three weeks or 21 days, which was comparable to the estimates of Ismi
5252
et al. (2012), that E. fuscoguttatus juveniles from an initial TL of 3 cm, could
5253
reach a final TL of 7 cm in 30 days. However, it is worth reiterating that our
5254
study used small basin with densities several times higher than the
5255
recommended density in tanks and cages (Ismi et al. 2012).
5256
5257
Factors affecting fast fish growth includes the maintenance of
5258
optimum water conditions, good nutrition and reduced stress (Ismi et al. 2012;
5259
Hien et al. 2016). The use of small basin instead of concrete tanks could
5260
further significantly reduce the cost in setting up a large hatchery, making this
5261
better suited for backyard or small-scale hatcheries. The results suggest that
5262
hatchery-produced E. fuscoguttatus could be raised at higher stocking
5263
densities in plastic basins without affecting their growth and survival. Other
5264
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
143
higher stocking densities maybe tested to optimize the use of space in small-
5265
scale hatcheries.
5266
5267
Table 11. Average total lengths (TL) and survival rates (SR) of Epinephelus
5268
fuscoguttatus in Experiment 3 in comparison with a similar study. CP-
5269
commercial pellets.
5270
5271
T
Starting
Density
(ind L-1)
Final
Density
(ind L-1)
Duration
(day)
SR
(%)
Final
TL
(cm)
Final
Weight
(g)
Feed
Culture
System
Source
1
6
2
21
100.00
6.94
6.16
CP
Basin (25
L)
This
Study
2
12
4
99.20
6.92
6.00
3
18
6
99.73
6.92
5.82
1
1
1
42
80.83
7.615
7.77
CP
Flow
through
Round
Fiberglass
tanks (80
L)
Salari
et al.
2012
2
3
3
82.77
8.492
10.45
3
5
5
80.91
7.852
8.90
1
1
1
78.33
7.211
6.92
2
3
3
84.86
6.942
6.90
3
5
5
79.58
7.212
6.74
5272
Experiment 4 (E4): Growth and Survival of E. fuscoguttatus
5273
Fingerlings Fed with Different Commercial Feeds
5274
5275
In this experiment, the fish in T1 having an initial 6.07 cm TL on the
5276
first week reached 8.51 cm TL during the final sampling on the third week
5277
(Table 12), suggesting 0.81 cm weekly average increase. Treatment 2 on the
5278
other hand performed a little slower having 0.62 cm average increase per week.
5279
This variation could be sampling or nutrition related. Samples were unmarked
5280
and were randomly taken each week for size measurement thus causing
5281
possible variations. However, the variation due to sampling could be minimal
5282
with 90 fish samples per treatment per week, and the relatively similar SD for
5283
both treatments. The faster growth in T1 could have been mainly influenced
5284
by the quality of the feed. The imported commercial feed used in T1 listed
5285
nutritional information (11% moisture, 44% crude protein, 7% crude fat, 16%
5286
ash and 3% crude fiber) in its label and manufactured to industry standards.
5287
By contrast, the label of local commercial feed used in T2 did not contain such
5288
information. The use of good-quality pelleted feed is one of the best practices
5289
during the nursery phase as low-quality feeds result in poor nutrition and
5290
increase the chance of cannibalism (Ismi et al 2012). In addition, Alvarez-
5291
González (2001) and Hien et al. (2016) reported the significant effect of the
5292
quality of feed on the grouper growth. The limited laboratory facilities
5293
hindered the conduct of independent proximate analysis for both feeds, which
5294
should be considered when doing future growth studies involving the use of
5295
commercial feed.
5296
5297
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
144
For E. fuscoguttatus measuring between 5 cm and 9 cm TL, Ismi et al.
5298
(2012) recommended stocking densities between 400 and 1000 ind m-3
5299
(equivalent to 0.4 to 1 ind L-1) for both tanks and cages. Our study however,
5300
showed that this could be increased up to 2-4 ind L-1 with high SR (99.11% to
5301
99.78%) when small basins were used as rearing containers. Information on
5302
the survival of grouper having similar size with the fish we used are limited.
5303
Ahmad et al. (1999) reported 85.5% to 93.8% survival for E. coioides raised in
5304
tanks and cages at 1 ind L-1, while James et al. (1998) did not mention the
5305
survival of E. fuscoguttatus raised in fiberglass tanks for 30 days (Table 12).
5306
The densities used in this study were much higher than the recommended
5307
number in tanks and cages, but we obtained a much higher SR compared to
5308
the 60% estimate of Ismi et al. (2012).
5309
5310
Table 12. Average total lengths (TL) and survival rates (SR) of Epinephelus
5311
fuscoguttatus in Experiment 4 compared with other similar studies. T-
5312
treatment.
5313
5314
Species
T
Starting
Density
(ind L-1)
Final
Density
(ind L-1)
Duration
(day)
SR
(%)
Final
TL
(cm)
Final
BW
(g)
Feed
Culture
system
Source
Epinephelus
fuscoguttatus
1
4
2
21
99.78
8.51
12.1
Pellet
Brand
A
Basin
(25 L)
This
Study
2
99.11
8.04
10.06
Pellet
rand
B
Epinephelus
coioides
1
1
1
30
93.80
10.9
Pellet
Tank
(2,800 L)
Ahmad
et al.
1999
2
85.50
10.6
Cage
(1,000 L)
Epinephelus
fuscoguttatus
1
0.2
0.2
30
14.28
Pellet
Rounded
fiberglass
(2,800 L)
James
et al.
1998
Epinephelus
polyphekadion
2
8.84
5315
In aquaculture, cannibalism can cause considerable problems in larval
5316
culture (Liu et al. 2017). Epinephelus fuscoguttatus tend to eat other fish very
5317
close to their own size (Ismi et al. 2012), but the absence of cannibalism in this
5318
study proved that the use of basin is a good practice in hatchery management
5319
to facilitate fast and effective grading of grouper fingerlings. Basins are also
5320
less expensive and easier to manage than concrete tanks and could easily be
5321
adopted in small-scale hatcheries.
5322
5323
5324
ACKNOWLEDGMENTS
5325
5326
This research was made possible through the USAID-STRIDE-RTI
5327
Grant number AID-492-A-13-00011. We are indebted to the assistance of
5328
Villanueva et al.: Propagation of Tiger grouper
The Palawan Scientist, 13: xx-xx
© 2021, Western Philippines University
145
April Pitong, Ariel Valoroso, Rodney Arcilla, Bryan Chua, and Robert
5329
Arangorin. The grouper eggs were provided by the BFAR Inland Sea Ranching
5330
Station. The two anonymous reviewers provided insightful comments and
5331
suggestions which helped improve the paper.
5332
5333
5334
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5436
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5439
5440
ARTICLE INFO:
Received: 08 November 2020
Revised: 25 January 2021
Accepted: 09 Feb. 2021
Available online: _ Feb. 2021
5441
5442
5443
Role of authors: EGV –gathered and analyzed the
data, and co-wrote the paper; KH and JvB –
conceptualized and supervised the conduct of the
study, and co-wrote the paper; APG-supervised the
conduct of the study and gathered the data; RGD –
analyzed the data and co-wrote the paper; LAC – led
the project and co-wrote the paper.
