A higher and centralized hatchery is planned on a state basis to service mainly the Ban Merbok brackishwater aquaculture ponds, the coastal aquaculture ponds along the west coast of the state of Kedah, and the fish cages at Langkawi Island.
The initial phase of the project will concentrate on small tank culture which utilizes a small water volume of not more than 5 tons1 (5 cubic meters) and the separate culture of larval shrimp food. Food for the finfish will be processed from trash fish and other (outside) sources, not cultured within the hatchery complex.
The choice of species for spawning and larval culture shall be both Penaeus monodon, P. Merguiensis for penaeid shrimp and Lates calcarifer (siakap) for finfish.
The selection of the site for the proposed hatchery facilities takes into account the following basic criteria:
The site area is where a shrimp fishing industry exists so that broodstock/gravid females from the natural grounds can be readily, easily, and cheaply obtained for spawning.
Transportation and communication facilities should be available for acquisition of gravid adults, acquisition of larval food materials, transfer of seedlings to the ponds and hauling of fuel and supplies. Gravid females brought from other areas should reach the hatchery within few hours after capture.
Electrical power is essential to hatchery operation and hence the site must have an adequate and reliable power source, both from the lines of a local electric company and/or from a standby generator.
Clean sea water, relatively free from silt should be available the whole year round. The site should be away from river mouths in order to avoid lowered salinities. It should be away from sources of pollution as well as from agricultural areas where heavy pesticides may contaminate the water. Freshwater should be available throughout the whole year.
There shall be an abundance of clear and bright days for outdoor and large-tank cultures. The site should be in an area protected from waves and adverse weather conditions.
The site should be near a mangrove swamp which may be converted and developed into nursery and rearing ponds and for the maturation of the broodstock. For year round hatchery operations, earthponds shall be constructed near the hatchery. Ovigerous females from the ponds can be available for spawning purposes.
Visits to three sites in Langkawi Island (Pulau Langkawi) were made during four days in the months of August and September. Comparative study of the proposed hatchery sites were made. The prospective sites shown in Fig. 25 are described below.
A coastal area near Kampong Penarak (Penarak Village) about two miles from the town of Kuah, is situated at a cove at the southeastern part of the island (Site II, Fig. 25). Adjacent to a possible hatchery site in this area is a small area of mangrove swamp. For water quality, the site is suitable. The area gives no room for expansion in the future. The village is not reached by the municipal power lines and there is no piped water mains. A high cliff rises on the southwestern part of the area, which condition may not be favourable for cultures that require bright sunshine.
Three-and-a-half miles from the town of Kuah is alternative Site I (Fig. 25) located on the southern part of Langkawi Island. The site is along the coastal road, near Kampong Bakau (Bakau village) rising about 40 feet above sea level. Below the area towards the southwest is a vast swamp of mangrove crossed by two fairly large rivers.
A site for the proposed hatchery could be where a rubber plantation is located, now being tapped for latex. The ground slopes gently towards the mangrove swamp, suitable for development into brackishwater aquaculture ponds.
Inquiries were made with JKR Kedah Utara (Office of Public Works), and it was gathered that the extension of the existing municipal water mains to the site has been programmed for 1980. Electrical transmission lines stop at the two-and-a-half milestone. The site is well protected from the southwest monsoon by Pulau Bunting (Bunting Island). Water is clear and apparently good for hatchery use.
Site III (Fig. 25) is located at the northern part of Langkawi Island near the village of Ayer Hangat (Kampung Ayer Hangat), a fishing village for anchovies, 14 miles (22 km) from the town of Kuah. Near this area is Pantai Ru (Ru Beach), a tourist spot famous for its wide, beautiful beaches. It was gathered from JKR that Pantai Ru has been programmed for development into a resort for tourists, and hence, the future availability of electrical power and communication line facilities when development is completed. An extensive network of rivers criss-crosses a vast mangrove area, mostly sandy near the coast. In terms of land use, the land could be expensive and acquisition difficult.
Site I (Fig. 25) appears to be the more suitable of the other two sites. The configuration of the land which is undulating towards the mangrove, makes it ideal for siting reinforced concrete saltwater and fresh water reservoirs and sand filters. Delivery of fresh and salt water to the hatchery and to the other buildings and facilities would purely be by gravity. Freshwater to the freshwater reservoir will not require pumping. It was observed that during high tides, the water is very clear but quite turbid during the receding low tides and during heavy rains. Sea water salinity is within the desirable limit range of 28 to 32 ppt.
Transportation facilities are available as the area is near the town of Kuah, where the presence of a jetty with landing facilities make easy transfer of seedlings, adult shrimp and handling of fuel and supplies.
The development into ponds of a vast mangrove swamp nearby would, in the future, be a constant source of pond-reared gravid adults and the hatchery produced fry can be reared in these ponds. Gravid females brought in from other areas can reach the site within a few hours. A ferry service is available in two runs daily, from the coastal town of Kuala Perlis in the mainland peninsula to Kuah municipality. This trip takes an hour-and-a-half.
Signs of pollution have not been observed at and nearby areas. Water salinity is expected to be always high throughout the year.
The following criteria give the guidelines in design of the proposed hatchery. These are tentative as much will depend on the nature of the site that will finally be selected, among other things.
Facility and programme for the proposed hatchery shall initially be oriented towards production.
Constant maintenance and replacement of materials and equipment due to the corrosive atmosphere will require that installations be in the open. If metals as brass are in contact with water, it should be covered with a coating of fiberglass resin or epoxy.
The design should be flexible with due regard to savings in energy, labour and expense. Smaller tanks may be combined with larger vats.
Present methods of culture1 and materials considered adaptable shall be utilized.
Water supply shall be by gravity. Freshwater and sea water reservoirs shall be sited on elevated ground.
Waste disposal should be properly planned. A lagoon may be built for dumping waste after it goes through a septic tank.
Plumbing will be over-designed to allow for increased flow if necessary for future changes.
The size, number and types of design of the culture tanks may vary to meet production demands. Spaces are reserved in the building area for increased demand.
Positioning of the tanks in the building shall be such that the tanks get the maximum amount of sunlight.
1 The Galveston method is to be adopted.
Extend intake pipe well beyond the low tide levels. Reduced pipe flow rates due to fouling shall be prevented by adopting a method that kills fouling organisms1. Pumping of sea water is done once a day for a period of 4 hours during the day high tides.
The use of PVC or asbestos cement pipes and PVC valves shall be preferred. Elevation of the reservoir shall be such that a fairly low water pressure is maintained.
There shall be two salt water reservoirs of reinforced concrete, circular tank on an elevated ground. Supply of sea water to the hatchery facilities is purely by gravity. The inside walls of the reservoir shall be plastered smooth to facilitate cleaning.
Piping shall be installed such that freshwater can be used to flush out all sea water pipes.
Reservoir capacity shall preferably be 15 tons per tank and shall be always kept full by pumping once a day. Diameter to depth ratio shall be large.
There shall be one freshwater reservoir.
Freshwater may be obtained from the municipal water system or from a water well (deep well).
The freshwater reservoir shall be of reinforced concrete circular tank on elevated ground. Supply of freshwater to the hatchery and other facilities is by gravity.
The use of galvanized iron pipes may be allowed for the distribution of freshwater.
Freshwater reservoir shall be of 10 tons capacity.
1 See Cook (1977), SCSP-SFDC/AEn/CP13
Maturation tanks are to be stationary structures of reinforced concrete. These tanks are to be used for the holding of the broodstock and for the maturation of the gonad after ablation.
Tanks are rectangular, of the outside dimensions, 5 m × 8 m × 1.40 m deep, consisting of: one part - filter side, other part - holding side.
The bottom and side corners are rounded and so the inside of the tank approaches an avoid shape in order to have better circulation of water.
Provide a water exchange siphon. This is an inverted U-shaped structure made of PVC pipe. The length of each arm is dependent of the size of the tank and the inside water filter box. A water inlet funnel with a stopcock is attached at the top of the siphon and a valve near the end of the outside arm. To operate the siphon, shut off the outside valve, open the top stopcock and pour water until the tube is full. Close the stopcock. To exchange water in the tank, open the valve for clean water inlet.
Provide a water exchange filter. A filter box is used constructed of hardwood and measuring about 0.30 m × 0.30 m × 0.80 m high. Two layers of screening material are attached to the frames, the inside screen of 3 to 4 mm openings to support the outside screen of plankton netting material of about 350 microns openings. The inside arm of the siphon is inserted inside the filter box.
Maturation tanks shall be located near the entrance.
There shall be provision for the installation of screens for grading of broodstock.
Spawning tanks shall be 2.00 m diameter × 0.8 m depth. It shall be of PVC with aluminum frame, or of fiberglass material, and are portable. Ten tanks are required for the initial phase.
Spawning tanks shall be inside the building near the holding tanks and within the monitoring area of the building.
Tanks for the disinfection of spawners shall be of 20-liter capacity. Aeration during disinfection shall be provided.
Plumbing shall be provided for rinsing of the spawners with clear sea water before they are placed in the tank. Plumbing is provided for freshwater and for aeration.
The larval rearing tanks are adjacent to the spawning tanks and shall be inside the building. The roof of the building shall be of colourless, corrugated plastic or fiberglass material.
There shall be provisions for control of water salinity. Salinity may be lowered by the addition of freshwater.
Provide control or sensing of water level in the culture tanks. The use of a flexible hose attached to the end of the outlet valve will adjust the water level by adjusting the height of the terminal end of the hose.
The larval tanks shall be circular and of PVC with an aluminum frame. There shall be 10 tanks of 5 tons capacity, each tank measuring 3.35 m diameter and 0.90 m depth, and 4 tanks of 14 tons capacity each measuring 7.30 m diameter and 1.20 m depth.
Half the number of larval tanks shall be conical, so that the Galveston method of larval rearing technique could be adopted. All tanks empty through 0.10 m (4 inches) PVC valve located centrally at the bottom.
For the 5-ton tanks, the stocking densities can be from 250 000 to 500 000 nauplii per ton. Assuming 14 runs per year, one run lasting 16 to 18 days, yearly per tank production would be 3 500 000 nauplii. Ten tanks would produce 35 000 000 nauplii. Assuming 30 percent mortality net production would be about 11 000 000. Similarly 4-ton tanks would produce 12 320 000 nauplii. Total production at full capacity would be 11 000 000 plus 12 320 000 or 23 986 000 nauplii. Half this valve for initial hatchery operation will more than suffice for the pilot project demand at Ban Merbok.
Provide water exchange filter.
Provide a depth marker for water exchange, mixing estimates and for population estimates.
Production of clear and clean sea water requires the use of gravity rapid sand filter. Two units of similar capacity are placed adjacent and operated in parallel. Each unit will be designed for a rate of filtration of 2–3 gallons (13.63 liters) of water per minute per square foot of bed area, with beds of 30 inches (0.30 m) thick of sand, 0.35 to 0.45 mm effective grain size.1
The depth of the reinforced concrete filter basin would be about 8 ft. (2.44m) or more, to include an under drain system below layers of gravel and sand, and a water depth of 3–4 ft (0.915–1.22m) plus a freeboard of one foot (0.30m).
The inner side walls should be roughened to discourage streaming of water between the walls and the sand. The influent pipe is to be discharged behind a baffle wall. Washing of the filter is done by reversing the flow of filtered water upward through the filter to remove the mud, etc., lodged in the sand. The wash water leaves the filter through wash water troughs placed above the sand bed. Rate of application of the wash water, supplied by gravity from the elevated freshwater reservoir of 30 ft (9.14m) above the bed is 15 gallons/min/square foot (1.9 liters/min/m2) of bed surface area. This produces wash water rise of 24 inches (0.60m) per minute. The quantity of water required for backwashing is about 2 percent of the total water filtered and the period between washings could be about 7 days or more.
The freshwater reservoir in addition to other requirements, should hold water enough to wash two filters for about 5 minutes each. A wash water rate controller may be incorporated for the desired wash water rate. The pump operates automatically by means of a liquid level sensing device. The wash water after passing through the filter is discarded.
A filtered water waste valve is provided which permits wasting of filtered water to the sewer for about 5 minutes before opening the effluent valve. A valve for the surface wash may be provided to supplement conventional reverse flow. The water level over the filter beds is controlled by liquid level sensing devices.
Fig. 26 shows the position of the filter beds in relation to other units. The filtered saltwater reservoir, previously explained, is located below the filter bed. The filter bed is designed to a capacity of 4 hours of 4 hours of pumping output during high tide. Sand filtering may be bypassed as pumped seawater can be brought directly to the seawater reservoir.
Single phase current will generally be satisfactory up to 10 hp but a three-phase system is preferable. Voltage shall be 220 volts of alternating current (VAC). Install all-weather fixtures if this is feasible. Use plastic instead of metal conduits for enclosed wiring if this is allowed by the building code. All outlets should be in the ceiling at many places. Extension cords are inserted into electrical outlets and these extend to at least a meter from the floor.
A standby generator is necessary. Power failure will alert the technician so he can start the generator. Synchronous motors shall be preferred as their efficiency is generally higher than other types. Power factor may be made unity by varying the exciting current.
It is sometimes desirable to use two or more pumps in parallel rather than a single larger pump. One pump can be shut down when flow requirement drops, the remaining pump allowed to operate closer to its peak capacity. Repairs or maintenance work on one unit could be done without shutting down the entire system. Special care must of course be taken in selecting pumps for parallel operation, the shut-off head for the two pumps in parallel being the same as for a single pump operation. Both pumps shall have similar characteristics.
A centrifugal type of pump is considered as it has the advantage of large capacity and low first cost. It is simple, no valves, few moving parts and dependable and suitable for sandy water.
Emergency power sources, as gasoline/diesel engines should be provided and these should be installed appropriately coupled to the pump should its use be needed. Pump performance is shown by its typical characteristic curve which shows the total dynamic head, brake horsepower, efficiency and net positive suction head. The materials of construction recommended for pumps handling seawater is bronze fitted; stainless steel shaft with mechanical seal.
Suction piping size and design should never be smaller than the suction connection of the pump, at least one size larger. Suction pipes should be as straight as possible and pipe velocities in the 5–8 foot per second range. Suction pipe slopes gradually from the source of supply. A long radius elbow is used to connect the vertical points of the suction line at least 2 diameter distance from the pump. Eccentric rather than concentric reducers are used. A foot valve and strainer is attached to the suction end.
Main delivery pipes from the reservoir to the hatchery should be 0.10 m internal diameter. The main pipes shall preferably be asbestos or PVC.
Brackishwater and freshwater lines should be connected so that freshwater can be used to flush out all saltwater lines periodically. All dead ends of piping should be fitted with a valve instead of a cap so that stagnant water in the lines can be drained. Plumbing for secondary saltwater supply shall be of PVC pipe, fittings and valves of schedule 40. Because PVC pipes can easily break at the valves, cut-off valves shall be installed on the main supply line in each section of the building for emergency shutdown. Black PVC is recommended for use especially outdoors as it is not affected by sunlight.
Two 0.10 m main water supply lines, one for fresh and the other for sea water, will be installed along all walls of the hatchery building. Auxiliary water supply lines to the components of the hatchery shall be 0.058 m (2 in.) internal diameter.
There shall be a storage room containing a complete set of fittings for all sizes of pipes, PVC glue, tape, hacksaw and measuring tape. The technician, to operate the hatchery, shall be familiar with all the plumbing installation so that use, operation and repair will not be difficult. It is a good practice to colour code the pipes and the central valves.
There should be no direct drainage to the concrete floors. Drainage shall be by covered sumps, located properly and throughout the building. The sumps empty into open, concrete lined ditches.
Roots-blowers should be used instead of compressors, in providing oil free oxygen in the culture tanks. Install two blowers outside the hatchery building. A low pressure, high volume aerator will be used for all tanks.
A secondary shaft should be fitted to each blower for an on-line gas or diesel engine in case of electrical failure. The engine's exhaust should be away from the intake manifolds of the air blowers. Blowers are installed outside the hatchery building. Sound proofing of the blower/engine should be provided. Care is exercised to bleed the excess air. The main air supply shall be PVC schedule 40 (0.025–0.051m) internal diameter with one pressure relief valve and brass pipe valves. This is branched into a multi-valve outlet system.
The auxiliary supply lines shall be plastic tubing, 9 mm inside diameter. Gang valves are used to disperse and regulate the air to the individual hatchery tanks, with aerators/air stones of carborondum, 3 cm in diameter and 9 cm long at the rate of one air stone per 5–10m2 of water. One air stone per 3m2 of tank bottom is used for the breeding tank. A heavy sinker is tied at the neck of the air stone.
Blowers operate 24 hours a day. Two Conde No. 6, 1.5 hp, threephase 25 cfm with auxiliary filters are suggested. A relay type of warning system is required should there be a sudden failure of power.
The use of airlift tubes is recommended as another method for increasing water circulation and movement of suspended food materials in the water column. A piece of polyvinyl chloride pipe of about 3 cm is held vertically in the tank, extending from near bottom to the water surface. A plastic tubing with an air stone at the end is inserted into the pipe, the air stone positioned at the bottom of the pipe. To the surface end of the pipe is connected a piece of elbow fitting and the direction of flow positioned. For a one-meter deep tank, 0.036 cubic meter of air is required for every square meter of area.
Cook (1977) presented a design of an airlift pump for water movement. This shall be incorporated into design of a modified raceway for culturing post larvae.
The initial phase of hatchery operation will require a building of the size shown on the plan (Fig. 27). Space for future building extension shall be reserved. Roof frame shall be of steel trusses. This is to admit more light as possible. The roof covering shall be colourless corrugated plastic sheets, preferably with mylar sheets laid above it to prolong the life of the sheets. Roof covering over the spawning area shall be opaque, asbestos cement corrugated sheets, for control of photo periods and temperature.
Ventilation shall be well provided. This is attained by the installation of monitors at the roof ridge. Cross ventilation is provided by fixed louvers at all walls of the building above the windows. There shall be no overhang of the roof; a green house effect is to be obtainable.
The building is designed to accomodate a mechanical conveyor for heavy equipment, etc. The building is to be oriented so as to receive the most sunlight as possible during the entire day. The floor shall be of concrete slab on fill with the required slopes for effective drainage to covered and grated canals. All piping and electrical wiring shall be exposed to ensure easy maintenance and repair.
Ceiling height above the floor shall be such that overhead pipes and electrical installation are within easy reach when used. Windows shall be provided with screens, if necessary.
