Why grouper culture?
· A high-value species with great demand in the local and export markets
· With prudent pond management, grouper is easier to culture than shrimp, without the attendant disease problems
· Wild and captive grouper broodstock spawn year round, hence, fry are available anytime of the year
· The technology of cage culture is relatively cheap and easy to run
· Culture can be done in ponds or cages
Grouper is a high-value species like tiger shrimp, and with prudent pond management, grouper is easier to culture without the attendant disease problems with prudent pond management. Shrimp farmers seeking alternative crops have found one in grouper.
Preparing the ponds for grouper is similar to milkfish and shrimp pond preparation. In addition, grouper fry or “tiny” need to be nursed first and must be regularly sorted and size-graded. Rectangular net cages supported by bamboo poles and installed inside the pond can serve as nursery. A hover-type lamp can attract live food for the grouper fry. Nursery takes about a month.
At the same time that grouper fry is stocked in the nursery, adult tilapia are released into grouper grow-out ponds so these, too, have a month to reproduce. Tilapia fingerlings will then serve as prey to grouper fingerlings from the nursery. In addition to tilapia, chopped trash fish and/or a formulated feed for carnivorous species may be given to grouper.
Regular monitoring and water changes are part of the pond routine for taking care of the stock. Grouper takes 5-7 months to attain a market-size of 400-800 g. If marketed live, fish farmers need to install temporary nets and tanks where grouper can be held while awaiting buyers and the completion of live packing for transport.
(1) Prepare the ponds like you would for milkfish. Stock adult tilapia at 5,000 to 10,000 per ha; its fingerlings will later serve as food for grouper.
(2) Install nursery cages if 2-3 cm fry are the only ones available for stocking the grow-out ponds. Bigger-sized fish (5-10 cm) can be stocked directly. Rectangular net cages can be used, and these are kept upright with bamboo or wooden support. Cage size varies, from 4 x 2 x 1.5 m to 8 x 4 x 1.5 m. Net mesh size is 0.5 cm. Stocking density is 60 fry per m3
(3) Install 50-watt incandescent, hover-type lamp in every cage, about a foot above the waterline, to attract mysids, copepods, and other young fishes and crustaceans at night. These are live food for the grouper fry, although they may also be given finely-chopped trash fish and/or mysid shrimps or “alamang.”
(4) Sort and grade the fry weekly to minimize competition for space and food and prevent cannibalism. Make sure there are extra ne tcages for the sorted stock.
(5) Transfer fry to grow-out pond when they are bigger, about 5-10 cm, usually after 30-45 days in the nursery. Stock at 5,000 per ha.
(6) Check if there are already tilapia fingerlings in the pond. There may be a need to feed more, so give chopped trash fish at the rate of 5% of grouper biomass per day. Give half of the feed in the morning, the rest in the afternoon. Place half in a feeding tray for monitoring purposes, and broadcast the rest. If using formulated feeds, take the advice on the feed label. Overfeeding leads to rapid deterioration of water quality.
(7) Do the routine pond activities: monitor water parameters (dissolved oxygen, salinity, temperature, depth), change water as the tide dictates, take weight-length measurements of some of the stock so that feeding can be adjusted.
(8) Selectively harvest in 5-7 months when some of the grouper are already market-sized (400 to 800 g). Harvest by using modified liftnets placed at the pond bottom. Provide shelters like sawed-off bamboos or PVC pipes in the middle of the net. Carefully lift the net in early morning when most of the grouper hide themselves there. Take only the biggest fishes and transfer to a pre-installed net that is 4 x 8 x 1.5 m with 1-2 cm mesh size. Stock the harvested grouper at 20 per m3
(9) To pack live grouper for transport, place 3-5 fish inside double-sheeted plastic bags with enough water to cover the nostrils of the grouper. Close the bags and pack in standard styrofoam boxes. Place crushed ice on top of the plastic bags to keep fish cool.
a. Expected gross revenues – P846,720 from two runs in one year from a production of 1,512 kg per run or 3,024 kg per year sold at P280 per kg ex-farm.
b. Internal Rate of Return (IRR) – 367% at 10% discount rate for 5 years.
c. Return on Investment – 81%
d. Net Present Value (NPV) – P552,959 at 10% discount rate for 5 years
e. Benefit Cost Ratio (BCR) – 1.22
Marine cage culture of Grouper
The technology of cage culture is relatively cheap and easy to run. The materials used in construction are indigenous and readily available like the bamboo supports. Filipinos are used to working with bamboo. In addition, grouper fry can now be produced in hatcheries or transported from areas where fry collection is an established industry, and there are a lot of places in the country where this is so.
Marine cage culture of grouper can be done in 4- to 12-compartment cage as one unit. There are nursery (small mesh is used in the cage) and grow-out phases (larger mesh). Grouper need to be sorted and size-graded every week. Other routine procedures include feeding (trashfish and/or formulated feeds), net maintenance, stock sampling, and monitoring water quality.
Groupers can reach the market-size of 400-600 g in 6-8 months when 2.5-7.5 cm fry are stocked. The live export market has the best price to offer.
(1) Construct floating netcages, usually of size 5 x 5 x 3 m, and having 4 to 12 compartments. Attach floats (plastic drums, barrels) and sinkers or anchors (concrete blocks, etc). For the nursery cage, use a 0.5 to 1 cm mesh; for grow- out, use a 2-5 cm mesh. Place hides and shelters inside the netcage; these may be made of sawed bamboo tied in triangular bundles.
(2) Stock wild- or hatchery-reared fry (2-10 cm length) in nursery cages at 100-200 per m3. Install hover-type lamp to attract copepods and other young fishes and crustaceans; these can be eaten by the grouper. But give added feed like mysid shrimps or finely chopped trash fish at 10% of fish biomass. Feeds are divided and given 2-4 times a day. If formulated feed is also used, go with the directions in the manufacturer’s label. Do not overfeed; pollution can bring a fish kill.
(3) Sort, size-grade, or thin out stock every week. Transfer same-sized grouper to the next vacant cage. When groupers are twice as big as initially stocked, they can be considered in the grow-out phase.
(4) Do the same procedures as in the nursery: feed (reduced to 5% because large fish are over their growth spurt), size-grade and transfer,
monitor water quality, change the nets at least once a month, sample the stock, and monitor fish for diseases and parasites.
(5) Selectively harvest the 400-g or bigger groupers. Do not give feeds a day prior to harvest.
P187,545 broken into P35,545 for capital outlay (construction of cages) and working capital of P152,000 for one run. There are 6 units of cages with sizes at 5m x 5m x 3m.
a. Expected gross revenues –P302,400 per run (6-7 months per run)
b. Internal Rate of Return (IRR) – 390% at 10% discount rate, 5 years projections
c. Return on Investment – 59%
d. Net Present Value (NPV) – P290,104 at 10%discount rate, 5 years projections
e. Benefit Cost Ratio (BCR) – 1.15
|Size of net cage||5 m x 5 m x 3 m|
|Total number of net cages/module||6 units|
|Stocking rate per net cage||500 pcs|
|Size of initial stock||2.5 to 3 inches|
|Total number of stocks in one module||3,000 pcs|
|Culture period||5 to 7 months|
|Average body weight at harvest||450 grams|
|Croppings per year||1|
|Total harvest||1,080 kilograms|
|Feed conversion ratio||5:1|
Unit Cost (P)
|Wage of caretaker (months)||8||4,000||32,000|
|Repairs and maintenance||1,066|
|Depreciation of cages and hut||11,848|
|Interest at 14%||26,256|
|Total operating cost||191,170|
Source and Photo: SEAFDEC Aquaculture Department
For more information, contact:
SEAFDEC Aquaculture Department
Tigbauan 5021, Iloilo, Philippines
Trunkline connecting all offices:
(63-33) 5119170 to 71
Fax: (63-33) 3351008
Training and Information Division
Tel No.: (6333) 511 9172; Fax No.: (63 33) 511 8709
SEAFDEC Aquaculture Department
Room 102, Ground Floor
Philippine Social Science Center
Commonwealth Ave. corner Central Ave.
1101 Diliman, Quezon City, Philippines
Tel: (63-2) 455 – 0981, 927 – 5542
Telefax: (63-2) 927 – 7825
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