Brood Stock Management and Production of Seabass (Lates calcarifer) in Tawi-Tawi waters
|Project Title||:||BROODSTOCK MANAGEMENT AND PRODUCTION OF SEABASS (Lates calcarifer) IN TAWI-TAWI WATERS|
|Project Priority Area||:||Sanga-Sanga Channel, Bongao, Tawi-Tawi|
|Funding Agency||:||MSU-TCTO, Sanga-Sanga, Bongao, Tawi-Tawi|
|Project Leader||:||Mr. Ramon Y. Tañgon
|Implementing Station||:||Department of Research
|Date Started||:||September 2014|
|Expected Completion||:||September 2016|
Importance/Significance of the Proposal:
As the human population is continuing to grow, food security is one of the most important global challenges we face today. This is exacerbated by the fact that the landing from capture fisheries is declining (Katavic et al, 2005). With the successful development of induced breeding practices that create better broodstock handling and management, a number of hatcheries were established and developed in recent times (Hussain et al, 1999). Hence, control of broodstocks development is essential for the sustainability of aquaculture production.
The intensification of food production of the sea farming industry has grown considerably through the years. Fish culture techniques have evolved from the crude and simple to the more sophisticated fast growth rate and yielding methods. Therefore, the widespread demand for seed cultivation of highly valued marine fishes has greatly increased.
The common practice currently used in fish farming is from hatchery to fry and juvenile fish production with the size of 1 – 3cm from the tanks and after 21 to 25 days they will be transferred to the sea cages for nursery and grow-out until they reach marketable size and broodstock development. Seabass and snappers are cultured mostly using this technology (Katavic et al, 2005).
In order for the fishery industry farming to be successful, the availability of seed supply should be constant and steady. This can be better attained if the species can be produced in captivity. Consequently, this would break the dependency on the natural source of seed through the development of captive breeders.
Hence, this project deals with the knowledge on the broodstock management of seabass to make entrepreneurs and innovative fish culturists aware of the long-term advantage of establishing, developing, and maintaining captive spawners.
The present project is conducted to be able to:
1). Develop methods of mass production of fry and to determine the propagation method applicable to the physical and economical environment;
2). Provide self-employment opportunities among individuals who desire to engage in such activities;
3). Provide future sea farmers of Tawi-Tawi with adequate knowledge of mariculture management; and
4). Eventually, to make an income-generating institution.
1. Site of brood stock culture
The site of the broodstock farm is the present project where young seabass are being reared in Sanga-Sanga Channel, Sanga-Sanga, Bongao, Tawi-Tawi. It is accessible by land transport through a 3-minute ride to Sanga-Sanga airport.
The site is free from pollution, not overly exposed to prevailing winds and strong waves action. The flow current of the sea is normal providing good circulation of water and the depth of the site at lowest tide is 2.5 -4 meter clearance between the bottom of the net cages and seabed. Transparency of the sea occurs from 7.4 to 4.8 meters.
- Source and Selection of Breeders
One of the keys to the success of broodstock farming operation is the selection of a good and healthy fish. Production and performance quality are the most important traits for which fish are selected. The species must be free from disease, fast growing and active with perfect physical appearance and strongest and largest among their own group (Parazo et al, 1990). Good broodstock management and proper nutrition are essential to ensure sustainable supply of quality eggs and fry for stock enhancement (Reyes, 2014).
Matured seabass spawners may be obtained from the present culture at the MSU- TCTO Marine Research Station I, Sanga-Sanga Channel, Sanga-Sanga, Bongao, Tawi-Tawi. At one year and three months olds, their average weight is 1.3 to 1.5 kilos. These healthy breeders will be transferred to a newly installed fish cage made up of black polythelene screen nets and G.I. pipes 4 x 4 x 2.5m with the mesh size of 1.5 to 2”. Another source of possible spawners may be obtained from the wild weighing 2-8 kg caught either by hook-and-line, gill nets, fish pen (bunsud) or fish traps (bubu) often from the river mouths , lakes or in salt water. In addition, juveniles can be gathered from the wild and grow them in floating cages.
The broodstock should be marked or tagged for record keeping e.g. date stock, number of fish stock in each cage and keeping an adequate number of brood fish, medium-sized, at least the ideal size population brood stock starts at 75-100 breeders per cage ( Reyes, 2014) in order to select the best spawners in terms of size, maturation and breeding efficiency (Hussain et al, 1999).
Asian seabass (Fig. 1) spend most of its growing period about 2-3 years in freshwater such as lakes and rivers that are connected to the sea. Matured fish (3-4 years) migrate to the sea to spawn (Kungvankij et al, 1985). In SEAFDEC, male Asian seabass attained sexually adulthood at 2.5 years and females at 3 years (Reyes, 2014).
- Brood stock Development
Sources of seabass spawners can be collected from wild-caught adults and from cages or ponds about 2-6 years old species averaging in weight from 2 to 8 kg. It is recommended to use cage-reared spawners for they are already used to culture condition and can be developed into brood fish. However, breeders obtained from the natural spawning grounds can be used, but they should be first acclimatized under cage or pond culture for at least 6 months before they are to be used as breeders.
Seabass is carnivorous in nature and they feed voraciously on live fish. However, in captivity, they can be trained to feed on fresh trash fish. It will only take a few days before they can used to new feeds. Foods that are uneaten by the fish and have settled to the bottom of the cage should be removed to prevent from water pollution.
Fig. 1. Asian Seabass (Lates calcarifer sp.)
pressure on the abdomen following a head-to-tail direction and check for the presence of milt or if whitish substance comes out from the urogenital pore then the fish is male (Fig.4). For female spawners cannulation method is applied by gently inserting polythylene tube (0.8mm inner diameter) (Fig. 5a & b) about 10 cm into the urogenital of the fish and aspirate by mouth or syringe as the inserted end of the cannula is carefully withdrawn from the fish. If eggs comes out, take sample and measure the diameter of 25 to 30 eggs with a calibrated microscope. A female with an average egg diameter of least 0.40 mm is sexually ripe and ready for hormone induction.
Fig. 2. 2-Phenoxyethanol, an anaesthesia agent to stun the brood fish.
Fig. 5a. Cannulation method for female inserting gently polythelene tube (0.8mm diameter) into urogenital about 10 cm checking for the presenceof oocytes.
Fig. 5b. Schematic presentation of cannulation process.
A. Syringe to which is attached a 20 gauge needle and 10 cm of polyethylene cannula (Clay Adams POE 100). B. The location of the genital opening. C. Close-up of the genital area.
In sea cages, sample eggs are placed in a vial that contains 1 ml 0.9% saline solution(Fig. 6). Shake well, if the eggs are separated from the egg follicle then the broodstock is ready to induce spawning. In males only those with running milt are chosen.
Fig. 7. Lutenizing Hormone Releasing Hormone analog (LHRHa).
Before the hormone injection, the breeders should be measured and weighed (Fig. 8a &b) and the hormone requirements computed. The spawners should be injected intramuscularly below the dorsal fin or above the lateral line of the fish. Then, carefully lift a scale with a hypodermic needle of the syringe and inject the hormone at 5-10 scales below the dorsal fin of the anaesthetized fish (Fig. 9a & b). This agent injection may be done during daytime. After injection they will be transferred to the floating hapa net cage or to the hatchery tanks and maintain a 1:2 (female:male) sex ratio in the spawning tank or cage. Then wait two nights for the fish to spawn after injection. The schedule of the injection should be synchronized with the natural spawning time of the fish which occurs late evening from 1800 to 2000 hours. SEAFDEC reported that Asian seabass attained its age of sexual maturity for protandrous males 2.5 years and hermaphrodite seabass females 3 years.
Fig. 9a. Position for an LHRHa (liquid) injection of an adult Asian Seabass
Fig. 9b. Injecting the brood fish with LHRHa.
1. Egg Collection
Eggs collection shall be done early in the morning about 5:30 to 7am. Fertilized eggs of the fish stay afloat in the water and are very transparent. Collecting the eggs should be done by gently scooping them out from the hapa net, wash them repeatedly through a filter screen to remove debris i.e., organic detritus, plankton, etc. and transfer to a pail of seawater. Fertilized eggs are then again transferred to the incubation tank and provided gentle aerated seawater. Hatching will occur 14 to 16 hours after fertilization at 28oC and 32-33 ppt. The newly hatched larvae are then collected the following morning by scooping out with beaker and immediately transferred to the larval rearing tanks.
2. Larval Rearing
A typical larval rearing tank is rectangular in shape. Its volume ranges from 8-10 tons (7×1.2x 1m) and the stocking density for newly hatched larvae is between 50-100 larvae per liter. Another one utilized is a conical tank with 10-ton capacity of water volume. The initial stocking density of larvae is 30 ind/L. At 10 days old the density is reduced to 50% say 15 ind/L and further 6 ind/L when the larvae reached 20 days old (Parazo et al., 1980).
3. Feeding Management
After 24 hours hatching the larvae are passive swimmers and for the first two to three days, the larvae are not allowed to feed as they have obtained nutrient from their yolk sac. However, it is advisable to apply earlier larval feed to avoid starvation. Nanochlorum sp. ( chlorella or tetraselmis sp.) are added on the fisrt day to 21 days to maintain water quality and serve as food for the rotifers.
After three days, when the yolk sac has been fully digested, the larvae’s mouth start to develop. Brachionus plicatilis are then introduced as feed for the larvae and this will be maintained three times a day until the larvae reach day 10. On day 11 add rotifers to the rearing tanks at 15-20 ind/ml until larvae reach day 20. The density may be maintained daily by adding rotifers. On the other hand, artemia nauplii (brime shrimp) may be introduced from day 15 until day 25.
4. Water Management
Starting from 0 – 4th day no cleaning of the rearing tanks is allowed. From 5th until 10th day of culture, the larval rearing tanks will be drained and replaced daily about 20 – 30% of water volume. On day 11 until day 18, the water volume change will be 50% and 70% on 19 to 25 days. However, starting on the 5th day the rearing tanks should be siphoned off with feces and other debris that settled at the bottom of the tanks. This will be done every morning until harvest (25 days) (Fig.10).
Protocol for larval rearing of seabass
│← Nanochlorum sp. (3-5 x ind. 105 cells/ml) →│
│← 2-3 →│← 10 → │← 20 ind./ml rotifer →│
│← 1 – 5 ind./ ml artemia →│
│← Siphon the tank bottom →│
│←20-30%→│← 50% →│← 70% →│
│ │ │ │ ________ │
0 5 10 15 18 20 25
Days of culture
Fig.10. Feeding and Water management for larval rearing seabass
BROOD STOCK MANAGEMENT AND PRODUCTION OF SEABASS (Lates calcarifer) IN TAWI-TAWI WATERS.
Activity Status Prepartion:
(Months): 1 – 12
(Months) : 1 – 7 8 9 10 11 12
Activities : A B C D E F
Year One :
A – For the whole year, it will be feeding and monitoring of the
brood stock of seabass and changing net cages every
A – Feeding and monitoring continued and maintaining change
of net cages.
B – Selecting healthy and good brood fishes to prepare for
C – Induced Spawning of matured seabass.
D – Larval rearing.
E – Harvest and nursery rearing for young seabass.
F – Grow-out culture until marketable or for ranching.
- Personal Services:
1- Project Manager at P5,000/mon. x 24 mons. . . . P 120,000.00
1- Fish Cage Tech’n at 4,000/mon. x 24 mons. . . . 96,000.00
1- Caretaker at 4,000/mon. x 24 mons. . . . 96,000.00
4- Admin Staff at 1,000/qrt. x 8 qrts . . . . 32,000.00
Sub-total . . . . . . . . P 344,000.00
Maintenance and Operating Expenses:
A – Travel (Training, educational tour, etc.). . . . P 32,000.00
B – Materials and supplies . . . . . . . . . . . 575,420.00
Sub-total . . . . . . . . P 607,420.00
Personal Services . . . . . . . . . . . . . P 344,000.00
- Maintenance and Operating Expenses . . . . . 607,420.00
- Contingency (10% of MOE) . . . . . . . . . .
GRAND TOTAL. . . . . .P 951,420.00
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