 | Lates calcarifer |
CULTURE PRACTICES
Seabass are cultured in earthen ponds and floating netcages, in brackish as well as fresh waters. Cage culture in brackishwater inlets and bays is mainly practiced due to the high cost of land. Fingerlings are produced in hatcheries following the artificial maturation and spawning of broodstock. Suitable culture density is 20 individuals/m2. There are three types of cages commonly used: nursery cages and floating and stationary netcages for the on-growing phase. Nursery cages vary in dimension and are made of a wooden frame and nylon netcage with a mesh size of 1.0 mm. Mesh size is increased to 0.5 cm after one month to allow a better water flow. The floating netcages (usually 5.5×6×2 m) are hung from GI pipe, wooden or bamboo frames kept afloat by styrofoam blocks. Stationary netcages are fastened to wooden poles at the four corners and are set in shallow bays where the tidal fluctuation is narrow. The stocking density in floating netcages is higher than in stationary cages as the former are usually set in sites with better environmental conditions. Farmers usually use chopped fresh trash fish to raise the seabass to market size.
PRODUCTION
HISTORY
Seabass is naturally found in brackishwaters throughout the coast of Thailand. It is a high valued species and has a strong local and export markets. Seabass culture in Thailand boomed following the success in artificial spawning by the Department of Fisheries 20 years ago. At present, its culture is decreasing due to the massive expansion of marine shrimp culture. Seabass are mainly cultured in the southern provinces, particularly in Satun, Trang and Krabi. About 1,408 cages are operating and production output in 1986 was 928 MT.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Lates calcarifer | ||
| Source of seed | Artificial | |
| Culture method | Pond and floating netcage | |
| Yield/ha | 150 kg/cage; 2.5 MT/ha | |
| Market | Domestic and export | |
| Production area | 1,408 cages | |
| Status of culture | Developed | |
| Major constraints | Limited suitable areas | KEY MAP |
 | Epinephelus malabaricus |
CULTURE PRACTICES
Cage culture is popularly practiced in Thailand since it is relatively easy to operate. Fingerlings measuring 5–10 cm are collected from the sea and stocked in cages. There are three types of cages commonly used: nursery cages and floating and stationary netcages for the on-growing phase. Nursery cages vary in dimension and are made of a wooden frame and nylon netcage with a mesh size of 1.0 mm. Mesh size is increased to 0.5 cm after one month to allow a better water flow. The floating netcages (usually 5.5×6×2 m) are hung from GI pipe, wooden or bamboo frames kept afloat by styrofoam blocks. Stationary netcages are fastened to wooden poles at the four corners and are set in shallow bays where the tidal fluctuation is narrow. The stocking density in floating netcages is higher than in stationary cages as the former are usually set in sites with better environmental conditions such as deeper water, narrower salinity fluctuation and better water circulation. Juvenile groupers are fed on chopped fresh trash fish, usually sardines. The culture period varies from 8–12 months. Seedling supply is the major problem affecting this seafarming activity.
PRODUCTION
HISTORY
The estuarine grouper Epinephelus malabaricus is one of the most popular marine finfish species cultured in Thailand. The culture of this high valued species started some 10 years ago. At present, most of the culture sites are concentrated in the southwest provinces, however potential sites have been also identified in the inner Gulf of Thailand. Grouper fingerlings are collected from nature and grown to the marketable size of 400–800 grams in floating netcages. Production in 1986 was 2,553 MT.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Epinephelus malabaricus | ||
| Source of seed | Wild | |
| Culture method | Floating netcage and pond | |
| Yield/ha | 300–400 kg/cage (6–7 months) | |
| Market | Domestic and export | |
| Production area | 700 cages | |
| Status of culture | Developed | |
| Major constraints | Development of hatchery technology Lack of fry supply Lack of high quality food | KEY MAP |
 | Saccostrea commercialis Crassostrea belcheri Crassostrea lugubris |
CULTURE PRACTICES
Sites for oyster culture are usually on the hard, stable bottom of intertidal flats which support heavy collectors for spat attachment and growth. However, a variety of coastal environments have been exploited. Bottom, suspension and midwater oyster culture are practiced in Thailand, and for each type a number of different methods have developed. Rock culture is based on the use of natural rocks, which are usually piled in groups of 5–10 and spread in rows about 50 cm apart in each direction. The tray method is practiced in muddy bottom areas. Trays are usually built in any convenient size. A popular dimension is 100 × 80 cm with a height of 25 cm. Trays, which are mounted on stakes approximately 30 cm above the bottom, are built of strong wood and are fitted with a nylon net bottom. Culture on cement poles and pipes is commonly practiced. Juvenile oysters are fixed on the above structures with quick cement and then positioned in the culture areas over wooden or concrete stakes driven into the bottom. Oyster spat are collected using all kinds of cultch materials one of which is shell of Placuna placenta coated with cement.
PRODUCTION
HISTORY
Up to 50 years ago Thailand had abundant oyster resources from natural beds. These resources have gradually decreased due to over-exploitation and pollution brought about by a substantial population increase in coastal communities. To meet the growing demand for oysters in the country and to exploit foreign markets, oyster culture was first initiated in Chonburi, Rayong and Chanthaburi provinces, later spreading to the southern part of Thailand. In 1986 oyster production amounted to 580 MT most of which was derived from culturing Crassostrea belcheri in Surat Thani province.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Crassostrea belcheri | ||
| Source of seed | Wild | |
| Culture method | Bottom, pole and hanging | |
| Yield/ha | 19 MT/ha (2–3 years) | |
| Market | Domestic | |
| Production area | 1,100 ha | |
| Status of culture | Developed | |
| Major constraints | Lack of seed supply Limited suitable areas Poor quality control | KEY MAP |
 | Perna viridis |
CULTURE PRACTICES
The traditional system of culturing mussels in Thailand is the fixed method done by driving bamboo or mangrove poles into the sea bottom. The advantages of this system are the simplicity of the farming techniques and the low material and maintenance cost. After setting the poles, hardly any culture activities are involved. A major draw-back of the pole method is the loss of large portions of the originally settled spat. Major losses occur due to over-crowding which often leads to slippage, of whole mussel clusters, and predation. Regular management practices are limited to inspection of the farm area to reinforce or remove weak or rotten poles. Harvesting of mussels starts after 4–6 months when the mussels have attained a marketable size of 8–10 cm. Mussel hanging rope (raft) culture is also being carried out on a relatively small scale. Raft are normally used in sheltered waters not less than 3–4 m deep at low-water spring tide. Mussel ropes hung from the raft are usually 1 m above the sea bottom to prevent bottom predators from climbing up the ropes. Main advantage of raft culture is that the mussels are submerged all the time and feed constantly.
PRODUCTION
HISTORY
The green mussel Perna viridis is one of the most important bivalve species in terms of quantity produced in Thailand. Culture of this species has been practiced for more than 60 years. Culture areas are located on both the east and west coasts and major culture provinces are Chonburi, Chachoengsao, Chumphon and Pattani. The culture practice initially adopted was the fixed method. Mussel culture has since developed due to the simplicity of the culture method, availability of suitable culture areas and fast growth of the organism. At present 660 ha are being cultured.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Perna viridis | ||
| Source of seed | Wild | |
| Culture method | Pole and hanging | |
| Yield/ha | 60–100 MT/ha (7–10 months) | |
| Market | Domestic | |
| Production area | 660 ha | |
| Status of culture | Developed | |
| Major constraints | Refinement of culture technology Poor quality control Marketing Low price in domestic market | KEY MAP |
 | Modiolus senhausenii |
CULTURE PRACTICES
Suitable salinity level for culturing horse mussels is 8–35 ppt and turbidity level is 5–70 cm (Secchi disc). Spats are collected from natural settling areas and transferred to on-growing grounds where they are cultured for 4–8 months depending on the initial size of spat. Suitable culture sites require hard bottoms with a good mixture of silt, sand and mud and a water depth usually less than 2 m. The horse mussels can be exposed for short periods, preferably less than 1 hour a day. The marketable size of horse mussels is 2.5–4 cm shell length. The major constraint to expansion of this seafarming practice is the low market demand. However, horse mussels are becoming a popular feed for marine shrimp (Penaeus monodon) and therefore future production may increase to serve this purpose.
PRODUCTION
HISTORY
The horse mussel Modiolus senhausenii is distributed along the entire coast of Thailand and are particularly abundant off the coast of Surat Thani, Petchaburi and Chonburi. They are typically found in mangrove areas or sites with relatively firm bottoms. The culture of this bivalve species has not widely developed in Thailand probably due to the low market demand. Culture areas are mainly concentrated along the coast of Bangsai District in Chonburi Province, however potential sites have been identified elsewhere. Production in 1986 was less than 400 MT harvested from extensive culture grounds.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Modiolus senhausenii | ||
| Source of seed | Wild | |
| Culture method | Bottom | |
| Yield/ha | 75–200 MT/ha (8–12 months) | |
| Market | Domestic | |
| Production area | 240 ha | |
| Status of culture | Developing | |
| Major constraints | Low market demand | KEY MAP |
 | Anadara granosa |
CULTURE PRACTICES
Cockle spat are collected from natural spatfall areas and transferred to enclosed sites (pen), usually located in estuaries or coastal areas where salinity level is around 25 ppt. Cockle spat, ranging in size between 1,000–10,000 spats/kg, are initially seeded at densities of 450–1100 kg/rai (1 rai = 1600 m2). The culture density is reduced after 3–6 months. Cockle farms are 200 to 2,000 rais in size with a bottom slope usually not exceeding 15 degrees. Culture grounds with a steeper slope are undesirable due to large cockle losses as a result of wind and wave action. Water depth in the culture ground is between 0 5–1 m (below mean sea level) with an exposure period of 2–3 hours a day. Cockles attain the marketable size in 12–18 months depending on the initial size of spat. Major constraints affecting further expansion of this seafarming activity are: unstable seed supply, predation, environmental pollution and lack of an export market. Potential areas for cockle culture have been identified in various localities in Ranong and Trang Provinces on the Andaman Sea as well as in Chanthaburi in the Gulf of Thailand.
PRODUCTION
HISTORY
Cockle culture was first practiced 82 years ago at Bantaboon District in Petchaburi Province. It has since expanded to other maritime provinces such as Samut Songkram, Surathani, Nakhon Si Thammarat, Pattani, Satun, Trang and Ranong. This bivalve is a popular species in Thailand and every year consumption exceeds local production so that Thailand imports yearly several thousand MT of marketable size cockles and seed from Malaysia. Production in 1986 was about 7,000 MT a considerable drop from the previous year's. Fluctuating annual landings is a result of unstable seed availability.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Anadara granosa | ||
| Source of seed | Wild and imported | |
| Culture method | Bottom | |
| Yield/ha | NA | |
| Market | Domestic | |
| Production area | 1,400 ha | |
| Status of culture | Developed | |
| Major constraints | Lack of seed supply Predation | KEY MAP |
 | Penaeus monodon |
CULTURE PRACTICES
Two sizes of cages are typically used: a) 5–25 m2 with depths of 1–2 m, and b) 16–36 m2 with depths of 4–5 m. The mesh size of the netting used varies depending on the initial size of the shrimp larvae. These cages can be either floating or fixed to the bottom, particularly in estuarine areas. Post larvae are stocked at densities ranging between 100–200 individuals/m2. Shrimp juveniles are fed with trash fish, squid, mussels and commercial pellets. Artificial feed is usually used as a supplement particularly when the larvae are still small. The feed is placed on feeding trays which are hung around the cage. This method allows an easy inspection on feed consumption. Due to the intensive culture practice, nets require frequent cleaning in order to ensure a proper water circulation. Sorting shrimp juveniles according to size is usually carried out after the first month. Major problems affecting this culture practice are: high larvae mortality during the first month, bottom deterioration, net clogging and water quality fluctuations, particularly during the rainy season.
PRODUCTION
HISTORY
The boom in marine shrimp culture in Thailand during the past 5 years has drastically increased the price and reduced the availability of land. In 1988, over 250,000 rais (1 rai = 1600 m2) were under cultivation. To cope with such constraint, cage farming has been introduced for culturing the tiger shrimp. Initial culture trials using the above method have been carried out in Chachengsao under the supervision of the provincial Fisheries Station. This method has proved to be productive and efficient. Yields of 80–120 kg/25 m2 have been obtained.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Penaeus monodon | ||
| Source of seed | Artificial | |
| Culture method | Pen and floating netcage | |
| Yield/ha | 80–120 kg/25 m2 (3–4 months) | |
| Market | Domestic and export | |
| Production area | NA | |
| Status of culture | Developing | |
| Major constraints | Refinement of culture technology | KEY MAP |
 | Gracilaria spp. |
CULTURE PRACTICES
At present Gracilaria in Thailand is only cultured in ponds or netcages on an experimental basis. Gracilaria culture using the monoline method or polycultured in shrimp ponds are being tested. The culture period is usually 3–4 months. Optimum salinity range for culturing this red seaweed is 25–32 ppt and the water column should not be deeper than 0.5–2 m in order to allow good sunlight penetration. Production level achieved in pond culture has been 6,400 kg/ha/yr, while 50–100 kilogrammes have been annually harvested from seabass (Lates calcarifer) floating netcages. Major problems affecting the expansion of this seafarming practices are the lack of suitable culture techniques and trained personnel and the low price in the local market due to the absence of processing plants. At present local fishermen collect and dry the seaweed which is bought by middlemen at 30 baht/kg. The Department of Fisheries is conducting research and examining the feasibility of mass propagating Gracilaria and other seaweed species.
PRODUCTION
HISTORY
To date, four endemic species belonging to the genus Gracilaria have been identified in Thailand: G. tenuistipitata var. liui, G. firma, G. irreqularis and G. salicornia. Thailand exports annually about 20–200 MT of dry seaweed most of which is Gracilaria. Major export markets are Japan, West Germany, Hong-Kong and Malaysia. This agarophyte is mostly harvested from the wild and from the nets of floating and stationary fish cages. Rich natural beds are found in Songhkla Lake and in the shallow mudflats off Pattani Bay. Research on agar processing and culture techniques is ongoing.
TOTAL REGIONAL PRODUCTION
STATUS OF CULTURE
| TOPIC | SPECIES |  |
| Gracilaria spp. | ||
| Source of seed | Wild | |
| Culture method | Pond, bottom and floating netcage | |
| Yield/ha | 6.5 MT/ha (pond) ; 100 kg/cage | |
| Market | Export | |
| Production area | Experimental | |
| Status of culture | Experimental | |
| Major constraints | Development of culture techniques Low price in domestic market | KEY MAP |
