APPENDIX 11

PRESENT STATUS AND TRENDS OF SEAFARMING IN THAILAND

responsibility for all aspects of Brackishwater annimals (Shrimp, fish, mollusk and other), research, development, and extension. This includes hatchery, post larval development, breeding, and other biological suspects that influence culture.

Sea farming, in the context of what I am talking today, will be taken to mean the increase in the production of aquatic animals from an area in the sea or intertidal zone not include deteriorating nangrove forests or ponds through human activities.

At present, sea farming exists at many places along the extended sea-coast of Thailand. Most important commercial operations are centered around the estaurine areas of the main rivers, lakes, and intertidal coastal areas. Possibilities exist not only for the culture of finfish, principally sea bass and grouper, but also other economic species of crabs, molluscs and seaweeds. With regard to artificial breeding of these species. The Department of Fisheries Biologists succeeded in breeding all of these species, many year ago.

The main opportunities for increases in aquacultural production at present is from brackishwater species. An accelerated program of coastal aquacultural development will require an expansion of the extension service through training and demonstration. Accordingly, rapid development of shrimp pond, fish cage culture, and mollusc culture can spread to all areas of the Gulf of Thailand and the Andamand Sea coast as well.

Major species cultured

• Major species cultured as sea farming are listed below (overhead project No.1)

• Production from culture activities (pond and sea farm of the major species are listed in Table 1,2,3 (overhead projecter No.2,3,4) Export and import

Shrimp is the major exported product from coastal aquaculture but exports and imports exist for the other products are shown in Table 4. (overhead projecter No.5)

• Major species cultured as sea farming are listed below

Seafarming species

PRODUCTION OF SHRIMP CULTURE. 1981–1985

PRODUCT : TON

TABLE 2 PRODUCTION OF FISH CULTURE. 1981–1985

PRODUCT : TON

TABLE 3 PRODUCTION OF MOLLUSK CULTURE. 1981–1985

PRODUCT : TOM

Table 4. Exports and Imports of Coastal aquaculture Production 1987–1985

Table 5 PRODUCTION AND VALUE OF COASTAL AQUACULTURAL PRODUCTS

PRODUCT=TON
VALUE=1,000 BAHT

* INCLUDES HOY KRANG

2. Culture techniques for Sea Bass, Lates calcalifer

Until recently sea bass were a by product from shrimp farms. For more than 40 years sea bass have been produced in shrimp ponds in the coastal areas of Thailand. The method involved collection of sea bass fry from estauries near the river mouth, mangrove areas, and from shrimp ponds. The major problem was lack of fry for stocking. This problem limited the distribution of culture areas. In 1973, the Department of Fisheries succeeded in artificially spawning sea bass. With fry available the Department developed culture systems. Cage culture was demonstrated to be an effective system. Following the lead established by the DOF, the private sector has established both breeding and culture on a commercial scale.

During the last decade the Department of Fisheries succeeded in establishing different techniques for producing sea bass fry.

1. Artificial breeding
2. Natural breeding: Using male-female at a 1:1 ratio in the breeding tank. Using 12–15 pairs of breeders. Par 150 Ton Tan Breeding pairs about 3 years old. The method was used by Satul and NICA.
3. Harmone injection: The method was established at Prachuap Khirikhan Station and used by many private farms.

The Department of Fisheries can produce more than 30 million fry/yr. After 30–45 days when the fry are approximately 1–1.5 cm. in length they are distributed to farmers. The fry can be culture in brackish or freshwater areas.

The culture techniques for sea bass are as follows;

1. Earthen pond culture: using fingerlings 2–3 inches long (50– 100 grams/pc). Production period is 6 months to produce 400 kg/rai. Stocking density is 2/m2.

2. Cage culture: Well developed in southern and eastern part of the coastal area of Thailand. Cage dimension is 50 m3 (6 × 5 × 2). Production is 150 kg/cage/6 months. Stocking density is 12/ ³ and harvest weight is 500 grams. There are presently about 1400 cages of seabass in Thailand.

3. Pen culture: This system is not popular in Thailand because of the difficulty in finding suitable production areas.

Thailand is well known throughout Southeast Asia for sea bass. Large amounts of seed are exported to Hong Kong, Singapore, Malaysia, and Formosa.

3. Culture Techniques for Grouper Epinephelus tauvina and E. malabaricus

Grouper is a well known and popular fish for consumption in South east Asia. The fish can be cultured in ponds or cages. The fish is fast growing to the marketable size of 600–900 grams.

The Department of Fisheries succeeded in artificial breeding of grouper by harmone injection in 1981. Other methods of breeding include natural and artificial by the dry method.

Culture method is as follows; The fry are reared in a net cage until reaching 5–8 cm. feeding is with chopped fish. After attaining sufficient size the fingerlings are transferred to a net cage 5×5×2 meters at 7,000 per cage. The fish are fed with trash fish until attaining a weight of 400–500 grams. The culture period is usually 6–7 months in length and food conversion ratio is 1:5–6. Production is 300–400 kg per cage.

Cage culture of grouper is distributed throughout southern Thailand. There are about 600 cages in the coastal zone and total value of production exceed 18–20 million baht/yr.

Shortage of seed remains as a constraint to expansion of production. The Department of Fisheries is conducting research on rearing the larval stages of the fish. After the techniques have been established the technology will be transferred to the private sector.

4. Oyster culture

In general there are four species of oyster found in the coastal waters of Thailand. The important and valuable species for culture purposes are Saccostrea cucullata, Crassostrea belcheri and Crassostrea lugubris. The former is distributed along the river mouths and coastal areas of Trat, Chanthaburi, Rayong, Chon Buri, and Prachuap Khiri khan Provinces while the latter is found in Krabi, Phangnga, Surat Thani, Pattani, and Chumphon. Oyster culture has existed in Thailand for more than 40 years. Several traditional methods have been practiced depending on the nature of the substratum. Stones, stakes, or concrete blocks may be used as substrate for attachment of the oysters. The oyster seed are micro organisms that prevail generally in the water mass. Pairoj (1974) conducted an experiment with C. lugubris growing on concrete culvert material. The oyster could be harvested after a period of 7–12 months. Yield was 40,000– 50,000 oysters per rai. For the small oyster, S. cucullata cultured in Chanthaburi Province, yield of 3 tons per rai is obtained.

At present, the oyster culture area is approximately 7,046 rai while the potential area for development is nearly 40,000 rai (Table 4). Recent production figures are 5,663, 8,422, and 5,171 tons for the years 1980 through 1982.

5. Mussel culture

Culture of green mussel has been carried out in Thailand for more than 60 years. The fishermen gained experience by first collecting mussels attached to the stakes of certain types of stationary fishing gear. It was relatively easy to convert to driving strong lengths of bamboo or date palm stakes into the muddy bottom of the intertidal zone as collectors of mussel spat. The method is commonly and successfully used along the coastal area of Thailand. The attached mussels are allowed to grow for a period of 6–8 months before harvesting for market. Pairoj (1971) reported that yield of about 10 tons could be obtained per rai.

In the Southern Provinces, it is believed that the first mussel farming began in Chumphon Province about 16 years ago. Promotion and extension has been slow due to the lack of natural seed in the coastal areas of Nakhorn Si Thammarat, Pattani, Surat Thani, and Phangnga. The Department of Fisheries has attempted to introduce adult male and female mussels into other areas. The first trial was attempted in 1977 at Pattani. Later, a transplantation was also made at Nakorn Si Thammarat and Phangnga. The results of these attempts have been moderately successful.

At present, mussel farms occupy an area of 4,132 rai while the potential area is estimated at approximately 66,282 rai for the 23 maritime provinces, (Table 4). Almost the entire production of green mussel is from culture activities.

6. Horse mussel culture

Horse mussel (Arcuatula arcuala) is an economically important bivalve in Thailand. Culture of this specie has been conducted for more than 30 years. In 1973, there were 730 rai of farming area. The area was increased to 911 rai by 1978.

Two methods of farming are usually employed; First, seed horse mussel, 5–10 mm in size, are spread over the mud flat at a rate of 9–10 tons/rai. After 8–12 months the mussels are harvested, by dredging, at a size of 2–3 cm. Production per rai ranges widely from 12–36 tons. Second, seed mussel are spread over the bottom of shrimp ponds. No research data are available on the yield per area.

The horse mussel, 2–3 cm in length, are sold for human consumption at 1.4 baht/kg. smaller horse mussel are harvested and sold for animal feed at a rate of 0.75 baht/kg.

The potential area for horse mussel production is over 28,000 rai or 450 hectares.

TABLE 4. EXISTING BIVALVE FARMS AND POTENTIAL AREA (1983) (CONT.)

7. Seaweed culture techniques

Thailand does not utilize large quantities of seaweed. Harvest is from natural beds. The Department of Fisheries is conducting research and examining the feasibility of mass propagation of seaweed species, especially Gracilaria sp.. This species of algae is found in Trat, Songkhla, Pattani, and Trang Provinces. Local fishermen collect the seaweed and dry for sale to middlemen for export. Price is about 30 baht/kg (approximately $1.10 U.S.) Total export in 1982 was 68 tons valued at 20,983,000 baht.

The Laver (Porphyra sp.) is collected from natural areas during the cool season (December-January). The main habitat is Songkhla Province. Production is very limited amounting to 100–300 kg annually.

7. Cockle Culture

Cockle farming has been conducted in Thailand for many years with the early farming located in Phetchaburi Province. In that area, approximately 50 centimeter high bamboo sticks are used to fence each producers production area. The average production area is 6 rai (6.25 rai equals 1 hectare). Farms are located in the mud flat or shore line adjacent to the mouth of the river or canal. The site must have sufficient width, intertidal, and have a small gradient. The cockle seed are collected from the wild in the same location. The prevailing species is Anadara granosa.

During the last decade a different method of culture has developed in the southern provinces, both on the Andaman Sea Coast and The Gulf of Thailand. Production is in the mud flat areas with water depth of 2–5 meters. Farm size ranges from 200– 2000 rai. Farms of this size require a tremendous amount of seed for stocking. More than 4,000 tons of cockle seed were imported from Malaysia annually. The species stocked is Anadara granosa. Seed are usually stocked at the rate of 540–1080 kg/rai. The seed are dredged after a certain growth period to spread them evenly throughout the area. The market size cockle are harvested after 12–18 months of growth. The period of culture is dependent on the size of seed cockle stocked.

TABLE 4: EXISTING BIVALVE FARMS AND POTENTIAL AREA (1983)