Grouper Culture in Chinese Taipei
T. W. Chu[1]
Abstract
A total of 84 species of the
family Serranidae are found in the surrounding waters of Taiwan but the
aquaculture industry cultures only 13 species of these groupers. The farming area for grouper has increased
by threefold from 1985-1995, i.e., from 192 hectares in 1986 to 576
hectares in 1995. The production of
grouper culture also increased 2.17 times in the same period. Seed for aquaculture are taken from the wild
and from 300 grouper hatcheries that employ the artificial propagation method
for breeding of and spawning by grouper.
From these hatcheries, a total of 20 million grouper fry is produced
annually despite the fact that industry still faces some problems in producing
juveniles in the hatcheries. Thus,
future directions for grouper culture includes enhancement in the techniques of
artificial propagation, improvement in sperm preservation, more understanding
of the study on the natural egg-laying environment, advancement in producing
suitable nutritional feed, and better treatment in combating fish diseases.
Introduction
A total of 84 different species of the family
Serranidae are found in the surrounding waters of Taiwan. These species can be further classified into
five subfamilies (Table 1), namely Anthiinae (25 species), Epinephelinae (52
species), Giganthiinae (1 species), Liopropominae (4 species), and Serraninae
(2 species) (Lee, 1990).
The history of culture of
groupers in Taiwan can be traced back to Penhu area starting from 1972 (Figure
1; Hu and Lin, 1984). Due to its rapid
growth and good profit, groupers soon became the most important marine culture
fishes in that area. The grouper
culture spread to and commenced in the southern coastal areas of Taiwan only in
the 1980s. However, the fry was all
supplied by the catches from Penhu area.
Due to the limited by the
number of seeds collected from natural environment, a catch of only 1.5~3
million per year, the research on artificial propagation techniques of the
grouper is imperative. In 1979, the Penhu
Fisheries Research Institute (PHFRI) successfully induced spawning by injecting
hormone to induce maturation of eggs of Epinephelus amblycephalus. The fertilisation rate was 10~35 % and the
hatching rate 5-11%. The seed only survived three days due to various reasons. The major breakthrough in reproducing E.
malabaricus[2] fry was announced in 1985
by PHFRI after years of continued research.
A total of 140,000 fertilised eggs were collected from six female
spawners and over 10,000 fry grew to the size of 6.5~12 cm. The survival rate was 14% (Huang et al.,
1986a; Huang et al., 1986b; Lin et al., 1986).
Table 1. Species of serranids found in Taiwan (from
Lee, 1990)
Subfamily
|
Genus
|
Species
|
Subfamily
|
Genus
|
Species
|
|
Anthiinae |
Anthias |
A.
pascalus |
Epinephelinae |
Epinephelus |
E.
areolatus |
|
|
|
A.
squamipinnis |
|
|
E.
chlorostigma |
|
|
|
A.
luzonensis |
|
|
E.
septemfasciatus |
|
|
|
A.
elongatus |
|
|
E.
latifasciatus |
|
|
|
A.
truncatus |
|
|
E.
caeruleopunctatus |
|
|
|
A. fasciatus |
|
|
E.
maculatus |
|
|
|
A.
pluerotaenia |
|
|
E.
hexagonatus |
|
|
Caprodon |
C.
schlegelii |
|
|
E.
melanostigma |
|
|
Holanthias |
H.
borbonius |
|
|
E.
trimaculatus |
|
|
|
H.
chrysostictus |
|
|
E.
tauvina |
|
|
Odontanthias |
O.
rhodopeplus |
|
|
E.
corallicola |
|
|
|
O.
unimaculatus |
|
|
E.
amblycephalus |
|
|
Plecranthias |
P.
japonicus |
|
|
E.
suillus |
|
|
|
P.
kelloggi |
|
|
E.
tukula |
|
|
|
P.
helenae |
|
|
E.
bontoides |
|
|
|
P.
yamakawai |
|
|
E. epistictus |
|
|
|
P.
whiteheadi |
|
|
E.
quoyanus |
|
|
|
P.
anthiodes |
|
|
E.
merra |
|
|
|
P.
wheeleri |
|
|
E.
akaara |
|
|
|
P. nanus |
|
|
E.
poecilonotus |
|
|
|
P. longimanus |
|
|
E.
morrhua |
|
|
Sacura |
S.
margaritaceus |
|
|
E.
bruneus |
|
|
Selenanthias |
S.
analis |
|
|
E.
awoara |
|
|
Serranocirrhitus |
S.
latus |
|
|
E.
fasciotomaculatus |
|
|
Tosana
|
T.
niwae |
|
|
E.
fasciatus |
|
Epinephelinae |
Aethaloperca |
A.
rogaa |
|
|
E.
rivulatus |
|
|
Anyperodon |
A.
leucogrammicus |
|
Gracila |
G.
albomarginata |
|
|
Cephalopholis |
C.
igarashiensis |
|
Plectropomus |
P.
laevis |
|
|
|
C.
boenack |
|
|
P.
leopardus |
|
|
|
C.
formosa |
|
Saloptia |
S.
powelli |
|
|
|
C.
argus |
|
Triso |
T.
dermopterus |
|
|
|
C.
sonnerati |
|
Variola |
V.
louti |
|
|
|
S.
urodeta |
|
Giganthias |
G.
immaculatus |
|
|
|
S.
sexmaculatus |
Giganthiinae |
Lipropoma |
L. susumi |
|
|
|
S.
miniata |
Lipropominae |
|
L.
japonicum |
|
|
|
S.
spiloparaea |
|
|
L. latifasciatum |
|
|
|
S.
analis |
|
|
L.
aragai |
|
|
Cromileptes |
C.
altivelis |
|
Chilidoperca |
C.
hirundinacea |
|
|
Epinephelus |
E.
cyanopodus |
Serraninae |
|
C.
pleurospilus |
|
|
|
E.
undulosus |
|
|
|
|
|
|
E.
retouti |
|
|
|
|
|
|
E.
bleekeri |
|
|
|
Figure 1: Main Production of Grouper
Culture in Taiwan
Cultured Species
Thirteen species of groupers
are being cultured in Taiwan (Table 2).
Some are wild seed caught in the surrounding waters of Taiwan, others
are imported from abroad (Lee, 1990).
The sources for the grouper seeds include the native spawners bred
domestically by artificial means, namely, Epinephelus amblycephalus, E.
malabaricus, E. coioides[3], E. tauvina, E. rivulatus, and Plectropomus
leopardus (Table 2; Hu and Lin, 1984).
The spawners are imported from abroad and fostered domestically by
artificial means, namely, the E. akaara, E. fuscoguttatus, E. lanceolatus, and
E. longispinis[4] all belong to this category
(Chen and Chen 1987). The seeds that
are imported directly from abroad are of the species Cephalopholis argus, C.
miniata, and Cromileptes altivelis.
Table 2. Species of groupers cultured in Taiwan
Species
|
Sources of Fry
|
Notes
|
|
Cephalopholis argus |
imported |
|
|
C. miniata |
imported |
|
|
Cromileptes altivelis |
imported |
|
|
Epinephelus akaara |
artificial propagation |
imported spawner |
|
E. amblycephalus |
artificial propagation |
native spawner |
|
E. coioides (= suillus) |
artificial propagation |
native spawner |
|
E. fuscoguttatus |
artificial propagation |
imported spawner |
|
E. lanceolatus |
artificial propagation |
imported spawner |
|
E. longispinis (= fario) |
artificial propagation |
imported spawner |
|
E. malabaricus |
artificial propagation |
native spawner |
|
E. rivulatus |
artificial propagation |
native spawner |
|
E. tauvina |
artificial propagation |
native spawner |
|
Plectropomus leopardus |
artificial propagation |
imported spawner |
Statistical Summary
The farming area for grouper has increased by
threefold in the past ten years, from 192 hectare in 1986 to 576 hectare in
1995 (Figure 2; Fisheries Yearbook Taiwan Area, 1986-1995). The production of grouper culture also
increased 2.17 times in the same period from 971 to 2,104 tons (Figure 3). The economic income from the culture of
groupers grew 5.05 times from NT $ 136,396,000 to NT $ 689,222,000 (approx. USD
25 million) (Figure 4). The overall
trend in the past ten years is increasing, even though suffering sporadically
short-term fluctuations.
Figure 2. Increasing areas for the culture of groupers
in Taiwan from 1986-1995
Figure
3. Grouper Production in Quantity by
Inland Culture and Marine Culture
Figure 4. Value of Grouper
production, by Inland Culture and Marine Culture in Taiwan, 1986-1995 in
thousand NT$
Taiwan has imported fry in 1989 and adult grouper in
1992 for the aquaculture industry. In
1989, the import of grouper fry was 19,934 kg for a total value of NT $ 15.9
M. The amount of imported grouper fry
has climbed to 2,110 kg with a value of NT$ 1.6 in 1995 while the live adult
grouper reach to 20,056 kg which is worth NT $3.6 M (Figure 5, 6).
Figure 5. Trends in the imports of livefish and fry of grouper in Taiwan from 1989-1995
Figure 6. Value of grouper Import in Taiwan, 1989-1995,
Thousand NT$
Figure
7. Quantity of exported fry and
livefish grouper from Taiwan from 1989-1995
The exported grouper fry is only a tiny 13-kg in
1989 but no adult grouper was exported at all.
Focusing on establishing the grouper culture, the Taiwan government
began inhibiting the export of grouper from 1992. The amount of the adult grouper exported in 1995 is 66,587 kg
with a price tag around NT $ 892,000 (Figure 7, 8). As a whole, the grouper produced in Taiwan mostly targets the
domestic market and exports only 3.16 % of the annual production in 1995.
Figure 8.
Increasing quantities of grouper export in Taiwan from 1989-1995
Culture Systems and Management
The grouper culture
in Taiwan, according to its phases of growth, can be classified into three
different culture farms.
1.
The fry farm - After being purchased from the hatcheries, the fertilised eggs are
first raised to 3 cm (30-40 days) to pass the dangerous period. The major food source at this stage is
zooplankton, including oosperm and larvae of bivalves, rotifer, larvae of
barnacles, brine shrimp, and copepods, and others. Developed to the stage possessing the appearance of grouper but
still without the coloration, the fingerlings are sold to the fingerling farms
at the cost of NTS 15 - 30 each.
2.
The fingerling farm - The fingerlings are further raised to the length of 6~9cm (15-25
days) by feeding frozen small shrimps and artificial feed common to other
marine fingerlings. By the time they
will attain the semblance of adult groupers and are robust enough to be
transferred to the outdoor pond, the fingerlings are sold to the fish farm at a
price of NT $ 40-80 each.
3.
The fish farm - The water temperature most suitable for the grouper growth is
ranging from 22°C to 28°C; water temperature lower than 10°C will prevent the grouper from taking
food. Salinity is maintained around 30
ppt but the grouper can adapt to changes of 1-4 ppt salinity. The adult grouper can be fed exclusively
with trash fishes, trash fish mixed with fishmeal, eel powder feed, or other
marine fish (e. g., seabass) artificial feed. In the farm, two different size-groups of grouper are placed into
different breeding ponds. This separation is important because of the predatory
nature of groupers and its territorial behaviour. The smaller fishes usually cannot compete with the bigger ones in
taking food or cannot avoid being attacked by the bigger ones. On the other hand, the larger grouper is
often found choking to death by taking smaller ones, which causes two
casualties instead of one. Fry usually
takes about 8 months to grow to its market size, weighing 600-700g.
Breeding
There are
approximately 300 grouper hatcheries employing the artificial propagation
method in the grouper reproduction. A
total of 20 million grouper fry is produced annually. The spawners come from three different sources:
Caught from the sea - April and May are the breeding months of groupers mainly in the
Penhu Sea in Taiwan. The local
hatcheries purchase the large-sized female spawner and then induce maturation
in the hatchery to promote the development of the eggs. It is then fertilised artificially with the
male spawner that is also caught from the sea.
The seeds from the fertilised eggs are then sold to the fry farms in
southern Taiwan.
Bred in pond - After June, the grouper spawners bred from the ponds located in
Taiwan will be brought together to mate naturally and to spawn in
captivity. They will be injected with
hormones from the salmon or catfish pituitary gland to induce maturation of the
gametes. Artificial fertilisation may
also be performed.
Imported from abroad - Due to the limited species of the grouper
spawners produced locally, spawner of large (Epinephelus lanceolatus)
species or economically valuable species (Cromileptes altivelis)
are imported from in Southeast Asian countries in the hope of increasing the
profits from the culture of groupers.
Grouper is a protogynous
hermaphrodite. The size of the female
grouper is usually smaller than the male counterpart. The adult male grouper is usually the dominant ones. Therefore, the collection of the mature male
grouper is not an easy task. Moreover,
the amount of sperms produced is not proportional to the size of the male
grouper.
In the hatchery, the methods
of breeding are artificial fertilisation and natural spawning. These steps are outlined briefly below:
1. Artificial fertilisation
·
examination
of the maturity of spawners - The following are the characteristics to guide
the examination:
Female - large, soft, and tender abdomen,
swollen towards both sides; dark red or orange genital aperture; maturity of
eggs (can be expressed and examined by using plastic pipette)
Male - maturity of sperm
which can be examined by applying pressure on the large abdomen to release
sperm. (Due to the fact that it takes
many years to breed a mature spawner and the low numbers of sperm per spawner,
do not apply too much pressure to cause stress and mortality.)
·
preparation
of injection dosage of hormones - use hormones from the pituitary gland, HCG,
etc.
·
injection
- sites of injection are either the back or the abdominal cavity
·
stripping
eggs and milt
·
fertilisation
- by the ‘dry method’ where eggs and milt are collected first and then mixed
evenly; seawater is added to the mixture after a few minutes and then poured
into a larger container.
·
egg-rinsing
- filtering out the dead eggs
2. Natural spawning - The grouper exercises fractional spawning.
Therefore, the quality of the fertilized eggs is better and the stress that
spawners experience is far less in the natural spawning setup. After the eggs are fertilized, they can be collected
into:
a. small ponds - Seawater is injected into
the pond forming water currents. A
plankton net is placed inside the water outlet to collect the floating
fertilized eggs carried by the currents.
b. large ponds - Paddle wheels are used to
create water currents. A plankton net is set up, circled in U-shaped, against
the direction of the currents to collect the fertilized eggs.
Future
Directions
1. Enhancement in the techniques of artificial
propagation
Even though the artificial
fertilization techniques of grouper in Taiwan have reached significant
improvement, there is still much to be desired. The female grouper, after
induction of maturation of eggs, cannot be simply put in the pond with the male
ones. The precision of the timing
squeezing-out the eggs from the abdomen are still not determined. The biggest problem lies on the mixing of
the eggs that have to be just right to increase the fertilization rate. Otherwise, even though fertilization occurs,
the quality of the eggs is not satisfactory enough to render good survival
rates.
2.
Sperm preservation
The amount of sperms that
the male grouper produced is very low.
In natural spawning, only one or two drops of sperm will be gathered
through the squeezing procedure. This is
the most common problem encountered in artificial fertilization. To ensure the availability of sperm for
fertilization with good quality of eggs, the preservation of sperms in a low
temperature environment (i.e., in liquid nitrogen) is important.
3. The study on the natural egg-laying
environment
The spawning habit of the
grouper is quite unique in that the male grouper will put its head tightly
against the female and rush out of the waters together while the female one is
laying the eggs. This behavior may be
attributed to the scarcity of the sperms[5]. Therefore, the water has to be at least two meters deep to
warrant the completion of the grasping and rushing movements.
The optimum time needed for
the egg to mature is the most difficult part to determine in artificial
fertilization for the production of viable eggs. The quality of the eggs has great impact on the success or
failure of the following seed breeding.
Due to the structure of the ponds and the rarity of the sperms of the
male grouper, to simply let female and male grouper naturally mate in the pond
does not allow good fertilization rate. Mating and spawning of groupers in
ponds is still a topic to be explored.
4. The study on the nutrition of the feed
Taiwan has not yet developed
a complete artificial feed specifically for groupers. The fundamental study on
the nutritional requirements of both fry and adult fish is still needed in
order to succeed in developing the artificial feed suited for the groupers’
growth. Also, the nutrition of the
spawners cultured in the pond is directly connected to the nutritional content
and balance inside the egg yolk, which in turn affect the breeding of the
grouper’s progeny.
5.
The study on fish diseases
The density of the culture
and the variety of fish species in the pond influence fish diseases. The major cause responsible for the death of
the grouper is due to Cryptocanyon irritans, which is a protozoid from
the sea. This protozoid cause damages
to the fish's skin and gill filament, block excretion, causing secondary
infection by some other disease. The
infected fish lacks appetite to eat, turning its body occasionally. Due to the protozoid parasites in the gills,
breathing is difficult. At night, the
oxygen intake will be insufficient, causing the infected grouper to float on
the surface of the water. The ones with
severe infection will submerge at the bottom of the pond. When one or two dead fishes are discovered,
the whole situation is already quite severe; the infection will spread all over
the pond in just a few days and the health of the broodstock will take a steep
downturn.
Literature Cited
Chen,T. F. and
L. L. Chen. 1987. The experiment for
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Chu, T. W. 1993.
Grouper culture. National Kaohsiung
Inst. Mar. Tech. 87 p.
Fisheries Yearbook
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K. J. Lin. 1984. Food and feeding frequency in rearing
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K. J. Lin, C. L. Yen, C. Y. Lin, and C. L. Chen. 1986a. Experiments on the
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Inst. 40: 241-258.
Huang, T. S.,
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C. S. Tu, and W. C. Su. 1977. Primary report of grouper, E.
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