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Grouper as warm water fish lately has been having
good price about Rp 70,000 (US$ 70.00 per kg) especially for big
restaurant in and outside the country. The grouper used to exported in
live to several countries such as Singapore, Japan, Hongkong, Taiwan,
Malaysia, and United States. High price and compatability of the
environment for grouper cultivation, as Local Government invited
Universities and Enterpreneur as partner to explore those challenge of
investment.
Feasibility studies conducted in Pangkalan Susu (Langkat, North Sumatera)
and Pacitan (East Java) to ensure the possibility for investment on
grouper cultivation using pond raising system or even floating
karamba system (karamba = local term for basket of dragnet
put in a stream / lake for raising fish). The studies as cooperation
between Local Gov't Pacitan Regency and researcher of Indonesian
University succeeded on maping 4 hectares potential area in southern
coast of Java. The closed distance to main consumer in Singapore and
large domestic market in Batam is another advantage for developing the
grouper rearing in Langkat, North Sumatera.
As not all coastal area suitable for rearing grouper, should the
location be considered for several main factors as followed :
1. Protected from big wave and typhoon as used to
stress fish and decreasing their
appetite.
2. Protected from predator threat which is marine carnivore and sea bird
3. Protected from industrial cesspool pollution, as well as compost heap
and
household wastage
4. Protected from up and down of big ship traffic as they created
wavelength and
ship disposal (diesel fuel)
Determining feasibility of location for cultivation grouper with
floating net karamba system basically using cradit value based on
several key parameter. The location will be categorized as good
as in range of 80 - 100; feasible as in range 70 - 79;
quite feasible as long as under qualified parameter could be
improved by technological approach; and unfeasible
criteria whereas the value below 60.
Species. Grouper has 46 species spread in several habitat,
grouped within 7 genus and 3 genus has been commercially reared so far
which is Chromileptes, Plectropomus, and Epinephelus. The commercial
species Chromileptes altivelis known as polka dot grouper or hump backed
rocked or in local term as kerapu bebek. The species has
grey body color with black spot. Their habitat cover such areas from
Kepulauan Seribu, Kepulauan Riau, Bangka, Lampung and ridge of rock
waters territorial. Another species known as Kerapu Sunuk
(coral trout) used to find live in coral waters. Also known as
kerapu merah due to their red or brownish body color and change
their color while in stress condition; and having blue spots. Habitat
areas from Kepulauan Karimunjawa, Kepulauan Seribu, south
ern Lampung, Kepulauan Riau, southern Bangka, and coral waters. Kerapu
Lumpur is local term for estuary grouper (Epinephlus spp) has black body
color, and some time called as black grouper. This species being a most
reared considering their fast growing. Habitat areas most ly in Banten
Gulf, Segara Anakan, Kepulauan Seribu, Lampung and estuary areas.
Rearing. Research Station so far faced a lot of obstacle in producing
grouper fry from artificial rearing. Farmers much depend on catch from
nature for their fry requirement using several devices such as fishhook,
lift up net tied between 2 rafts (or boats), 'sero' such kind of bamboo
trap used in rise and fall tides of waters, 'bubu' such kind of basket
of bamboo / wire plaited placed at the bottom of waters, dragnet pouch,
and pushing dragnet. Fry transported from the collection point to the
rearing area are put in 20 liter plastic bag, filled with 3 liter sea
water to hold 20 fry 25 gram body weight on average. Inside temperature
maintained at 17 - 20 Celcius degree for 1 - 2 days transportation.
Grouper in grower phase used to feed with under quality catch fish, cut
into pieces to suit the small opening mouth of the fish. Feeding 2 - 3
times a day. Entering the next phase (finisher), feeding rejected fish
given at 15 % of total biomass of the 20 - 50 g size of grouper. Feed
amount then decreased to remain 10 % of total biomass 100 gram size
grouper. The best time for feeding is right after rising sun or right
before sun set.
Market weight fro grouper is about 500 gram which is different between
species (400 - 1200 gram for estuary grouper; 500 - 2000 gram for hump
backed rocked grouper). Daily growth rate also differ depend on species
and body weight. Grouper with initial weight 50 - 100 gram will grow 2 -
3 % daily, meanwhile 200 - 300 gram grouper will have 0.7 - 1.5 % daily
growth rate. It takes 5 months of rearing to have 500 gram market weight
from 100 gram initial weight. Estuary grouper fed with rejected fish
will have 5 - 8 feed conversion ration, compared to 8 -12 of coral
trout.
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