Fisheries production in Thailand has demonstrated a remarkable growth over the last three decades. Total production exceeded 2 million t for the first time in 1977, then declined, but has been staging a recovery to over 2 million t again since 1982. In 1997, a record nearly 3.4 million t of products from aquaculture were harvested, of which 79.2% came from marine capture fisheries. Coastal aquaculture, freshwater aquaculture and inland capture fisheries contributed the remaining 8.8%, 5.9% and 6.1%, respectively (Table 1).
The country's total aquaculture production is divided into a) coastal and b) freshwater production. Freshwater aquaculture had a predominant role in the early days. However, coastal aquaculture has played an important role from 1988 onwards, due to the rapid development of intensive marine shrimp culture. In 1997, freshwater aquaculture shared 40.0% and 10.6% in quantity and value, respectively (Table 2) to total aquaculture production.
2.1 Production systems and species cultured
Fish farming practice is classified into four types:
Considering the number of farms and areas cultured, pond culture is the most popular form of aquaculture. However, in terms of productivity, cage culture has the highest yield. The main purpose of raising fish in paddy fields is to utilize the available water and to earn supplementary income.
The pattern of culture, either monoculture or polyculture, varies according to species raised. Monoculture is commonly practised for carnivorous species such as walking catfish and snakehead fish, and other peculiar species, such as freshwater prawns (Macrobrachium rosenbergii), catfish (Pangasius sutchi) and sand goby (Oxyeleotris marmoratus). Polyculture is generally practised for raising herbivorous species, namely, tilapia, silver barb, common carp, Chinese carp, and mrigal (Cirrhinus mregala). Nevertheless, some farmers, especially in the north, raise tilapia together with walking catfish in order to reduce tilapia fries. The species' high fecundity is an impediment to the growth of cultured tilapias.
Furthermore, the development of fish culture in Thailand has been designed to fit into the socio-economic condition of the rural population. Wherever possible, people are encouraged to culture fish in addition to raising pigs or poultry, fruit and vegetable and planting rice. Therefore, integrating fish culture with animal husbandry and/or cropping is a common practice in Thailand.
In 1997, the main species cultured were Nile tilapia, walking catfish, Thai silver barb, sepat siam, striped catfish and striped snakehead contributing nearly 90% in quantity and over 75% in value[31]. During 1977-1997, production of all species, except for sepat siam, rose significantly. Particularly Thai silver barb, walking catfish and tilapia posted tremendous increases in production, averaging 24.2%, 20.3%, 17.5%, respectively (Table 3). Tilapia, which accounted for over 33% of total cultured freshwater fish, is becoming increasingly popular in all regions, because the species is easy to grow and matures fast. Consumers are fond of Tilapia's taste, texture and price, which has not fluctuated much over the past two decades.
2.2 Production by regions
In 1997, fish from inland cultures were harvested from 168 972 farms that comprised a total culture area of 67 608 ha. Production areas were divided into six regions: the north, the northeast, the central plain, the east, the west and the south. Main species cultured differed slightly from one region to another. Nile tilapia was the number one fish raised in every region, except in the south and the central plain, where walking catfish was the most popular species selected for culture.
Table 4 illustrates that during 1977-1997, production increased significantly in all regions. However, the contribution of the east to total output fell from 54.4% in 1977 to 21.4% in 1997. Nevertheless, the latest figures show that shares to total production came mainly from the west, the central plain and the east. Each region contributed about 21-22% to total output. Supply from the northeast and the north was 16.8% and 12.2%, respectively, whereas the south contributed only 4.5%.
Of total area used for inland culture, 35.4% was concentrated in the northeast, followed by the east (28.8%), where half of the area consisted of paddy fields. Hence, the largest average farm-size amounted to about 1.24 ha (Table 5). The smallest farm-size of 0.08 hectare was located in the south. Generally, the average size of a farm for inland fish culture in Thailand is rather small, about 0.4 ha per holding.
A large number of farmers in Thailand use traditional methods for culturing fish and no additional feed. Some of them may use feed occasionally, or may utilize by-products from raising poultry. Every now and then, fertilizer is used to generate natural fish feed. Fish farmers in rural areas, particularly in the northern and northeastern parts of the country, raise fish for household consumption and to earn supplementary income. Most of these small-scale farmers earn a subsistence-type of living. Intensive culture requires high investments, especially in construction, fish feed and fingerlings. Thus, controlling the quality of the water and the time it takes to raise fish to harvest are important issues for all culture operations, particularly for farmers in the central plain, who raise walking catfish, and snakehead fish. A survey on the status of land holdings of fish farmers[32] found that 82.96% of them owned their land. Most farms were situated in the northeast, whereas the most productive farms were found in the central plain. Average output ranged from 880-5900 kg/ha.
