2. STATUS

2.1 General status

2.1.1 Area

Statistics on coastal aquaculture in this region have not been given adequate attention until very recently. Records of the areas of existing operations are therefore to be regarded only as approximate. These are shown by country in Table 10 on page 37, along with estimates of potential area for future development.

Coastal aquaculture in this region occupies a total area of approximately 427 000 hectares: fish and shrimp, 416 000 ha; molluscs and others 11 000 ha (see also page 36).

2.1.2 Production and average yield

A total of about 200 000 metric tons of fish and shellfish are produced annually: 160 000 metric tons of fish; 10 000 metric tons of shrimps and prawns, and 30 000 metric tons of cockles, oysters and mussels. The average yield per hectare per annum for fish is about 500 kg, and for shrimps about 350 kg.

2.1.3 Manpower

The total number of persons involved in coastal aquaculture operations has been estimated to be more than 200 000 full-time, with an average of about 2 ha of farm area per person.

2.1.4 Species cultured

About 40 species are being used for coastal aquaculture purposes. Among them Chanos chanos (milkfish), Mugil sp. (mullets), Anadara granosa (cockles), Crassostrea spp. (oysters) are very extensively cultured. Penaeid shrimps are cultured extensively but the methods remain mostly traditional; crabs, eels and other luxury finfish are being experimented with in pilot scale operations. Macrobrachium prawns have been given increasing attention. The farming of the green mussel (Mytilus) is spreading rapidly and could become a major industry.

A list of species cultured is given in Table 1.

2.1.5 Stocking material

Nearly all the stocking material - larvae, fry, juveniles, fingerlings - used in coastal aquaculture in this region is supplied from natural sources. The collection, rearing and supply of “seeds” has become an important industry auxiliary to the coastal aquaculture industry. It involves skilled personnel, and special gear and methods.

Experiments to produce seeds under controlled conditions are being conducted in many countries in the region. Those for the production of juveniles of Macrobrachium and some species of penaeids have achieved encouraging results. It is possible to produce limited numbers of young for experimental purposes; pilot scale production has been programmed, and large-scale commercial production is expected within 2–3 years.

Experiments on the induced spawning and production of fry of mullet have been done successfully in the laboratory, but large-scale production of seeds is still not ready. Induced spawning of the milkfish is still unsuccessful. The annual catch of milkfish fry is in the order of 7 000 million, all of which are collected from coastal areas.

2.2 Status by species

2.2.1 Finfish

Farming of finfish in coastal and estuarine areas has a history of over 400 years in Indonesia and the Philippines. Milkfish is the principal species and mullet next; both are non-carnivorous. For several centuries these species were almost the only ones to be cultured, and the use of carnivorous species for farming is a recent development. The cost of production of non-carnivorous fish is low and they are thus more suitable for the low income rural economy. On the other hand, while the production cost of carnivorous species is very high, the products often are of better quality and bring higher prices, and they are therefore suitable for a high income economy.

The farming of non-carnivorous species still depends mainly on natural food organisms produced in the pond, while the culture of carnivorous species depends on feeds introduced into the pond. But for both groups future development of the farming will depend a great deal on the development of efficient and economical artificial feeds.

The source of supply of seeds of most of the fish used for farming is from nature. Production of seeds under controlled condition is still experimental.

One important trend in the development of finfish farming is to practise intensive culture, using cages or pens in flowing open water systems where it is possible to have a very high stocking density and intensive feeding.

Milkfish

Milkfish culture is one of the most important coastal aquaculture practices in this region. It has great potentials for improvement and development (see Tables 2 and 3).

Culture management - Milkfish ponds vary in size from about 1 to over 100 ha. Those within the range of 5–10 ha are the most convenient to manage, especially when improved culture methods are practised. Management procedures can yield production figures from 1 000 to 2 500 kg/ha/year. Due to lack of skill and knowledge only a small fraction of the ponds in this area are at this level.

Economy - This industry provides a large number of jobs for fry collection, nursery operation, seed trading and farming operations. Most of these trades produce substantial profits.

Problems

1. The most important problem in milkfish culture is the availability of seeds. The present annual requirement of fry is in the order of 7 000 million, all of which are collected from their natural habitat. The occurrence of fry is unpredictable, and fluctuates widely from year to year and from place to place. In years of scarcity the supply of fry is far below the quantity required, the price is high and operators can only afford to have their ponds partially stocked, thus causing increases in production cost and decreases in yield. The importation of fry is often handicapped by restrictions and controls on export by the producing countries, and cholera outbreaks in supplying countries, causing prohibition of importation from these areas.

   Experiments to produce fry under controlled conditions by induced breeding have been attempted in the Philippines, but due to the lack of mature specimens and proper facilities no positive results have yet been obtained.

2. The problem of maintaining the salinity of pond water within the favourable range is serious in many localities, especially where there is no reliable supply of fresh water to compensate for the high rate of evaporation during the dry season, and where there is no efficient drainage system to divert rain water from the pond system during the rainy season.

3. There is lack of technical skill in pond management. Methods are traditional and “extensive”. Modern technology could increase production.

4. Development of new areas requires capital, and sources of financing are often scarce.

5. Whenever cholera occurs, the sale of milkfish, either for domestic consumption or for processing, is prohibited, causing great losses to the pond operators.

Mullet

Mullets are cultured in both freshwater and brackishwater ponds in many countries of this region. In Hong Kong they are cultured mostly in combination with Chinese carps, in the ratio of about 10 grey mullet to 1 carp.

Fry and fingerlings are collected from their natural grounds, acclimatized, and stocked in fishponds.

Experiments to breed this fish under controlled conditions have been conducted in many countries. The first success in rearing larvae hatched from eggs produced by induced spawning by hypophysation to fry and fingerlings ready for stocking was obtained in Taiwan Province in 1968–69. However, many problems such as high mortality and proper food and feeding must be solved before large-scale commercial production is possible.

Mullets cultured in brackishwater ponds can attain sexual maturity in 2–3 years, and are then suitable for spawning purposes. Pond-grown mature mullets will eventually become an important source of supply of breeding stock for mass production of fry and fingerlings.

Eels

The rapidly increasing demand and the high price of Anguilla eels in domestic and foreign markets has encouraged trials in eel farming operations in the Philippines, Malaysia, Indonesia, Thailand and Vietnam, with varied degrees of success. The main species used is Anguilla japonicus, while other closely related species acceptable to consumers are also being tried.

The sources of stocking material are either local waters or foreign countries - Japan, New Zealand, even European countries.

In most cases the management technique developed and practised in China (Province of Taiwan) and Japan have been introduced, and technicians from those countries have been engaged to supervise the operations.

Sea-bass, groupers, etc.

The very high prices and shortages of supply of some of the marine and estuarine fishes such as the sea-bass, groupers, porgy, seabream, siganids, snappers and gobies, have generated great interest in the development of practical methods for farming them under controlled conditions. This is a new venture in this region, and existing operations are still in the early stages of development, either as pilot trials or small-scale commercial operations.

The species used include:

All seeds used are collected from their natural habitats, and shortages of supply have often been experienced. Experiments to breed these fish under controlled conditions are being conducted.

Most of these species are active swimmers and are carnivorous; they thus require well oxygenated water and heavy feeding with high protein food. Farming operations are being conducted in ponds, pens, and floating net cages. Ponds and pens are constructed in coastal areas or cleared mangrove swamps, either by building a bund with sluice water gates or by fencing with screen or netting. The most important factor is an ample and constant exchange of water. Floating net cages are made of synthetic fibres or metal netting of appropriate mesh size. They are set on rafts or floats in areas well protected from storm and strong wave action and where the water is unpolluted and has a constant moderate flow. Stocking rates are very high and feeding intensive. In a net cage of 6 × 6 × 4 m, 1 500–2 500 fingerlings (5–10 cm in length and 10–50 g in weight) are stocked. At the end of one culture cycle (about eight months) the total net yield can be as high as 2 tons of fish.

Although this sophisticated, intensive culture of highly priced fish requires high production costs, in some cases the market value of the products is high enough to make it a very profitable operation.

2.2.2 Crustaceans

Shrimps and prawns

Culture practices

Marine species - Penaeids - Shrimp and prawn farming in the South China Sea region comprises a wide range of industrial practices, from the traditional trapping-holding operations to modern husbandry. The former is being extensively practised, while the latter is a recent introduction, in the early stages of development.

Existing cultural practices may be grouped into the following types:

Natural stocking - (trapping-holding-growing)

1. In shrimp ponds (Singapore, Thailand, Philippines, Indonesia, Malaysia, Vietnam).

2. In brackishwater fishponds (Philippines, Indonesia, Vietnam).

3. In coastal paddy fields (Vietnam).

Controlled stocking (farming/husbandry)

1. Seeds collected from natural grounds

   1. in brackishwater fishponds (Philippines, Indonesia);

   2. in shrimp ponds (Philippines, Thailand).

2. Seeds produced under controlled conditions (modern shrimp farming - at early stages of experimentation and development)

   1. in fish and shrimp ponds (Philippines, Indonesia);

   2. in shrimp ponds (Thailand, Philippines, Indonesia).

Natural stocking

In shrimp ponds - This method is best exemplified by the operation in Singapore. The ponds or impoundments are constructed in coastal, brackishwater, and estuarine areas where there is a wide tidal range and an abundance of supply of shrimp seeds. The water sluice gates of the ponds are carefully manipulated to control the inflow and outflow of water and maintenance of water level.

The stocking of the ponds depends entirely on natural processes. The sluice gates are opened during daily rising tide, allowing shrimp larvae and juveniles and other living organisms (including fish) to enter the pond with the rush of inflowing water. Wire screens are then placed across the sluice gates to prevent the escape of shrimp. The shrimp feed on the natural food organisms produced in the ponds and grow rapidly. Harvesting is done daily for about 7–8 days during each full-moon and new-moon period.

This method of natural stocking has the following disadvantages:

1. The natural supply of shrimp seeds fluctuates widely in species composition and in abundance from time to time, and it is therefore impossible to control the species composition and to maintain the density of population in the ponds at optimum level.

2. Many of the fish that enter into the ponds together with shrimps are predatory species, preying heavily on the shrimps.

However, being a simple operation that requires no special equipment or sophisticated management technique, it is being extensively done in many countries of this region, especially in Singapore, Malaysia, Thailand and Vietnam.

In fishponds - Many of the milkfish ponds in Indonesia and the Philippines are so located that they can be stocked with shrimps naturally by the same process described above. Such ponds are able to produce substantial amounts of shrimp in addition to fish.

In paddy fields - In Vietnam, large acreages of land around the estuarine and backwater areas are used for paddy culture during the rainy season after the salt is leached from the soil and the salinity of water is low. After the rich harvest the field is used as a shrimp pond, operated by the natural stocking process. Many of these paddy fields have been converted into shrimp ponds.

Controlled stocking

Seeds collected - The seeds are collected by professional collectors from estuarine areas, tidal canals and mangrove areas, using simple hand nets or tow nets.

The seeds are sorted, and those suitable for culture are separated into two groups -Penaeus spp. and Metapenaeus spp. - and are sold to the pond operators for stocking, mainly in milkfish ponds, but some in shrimp ponds without fish.

Seeds produced under controlled conditions - The technique developed in Japan is used to produce young for experiments in Thailand, Philippines, Malaysia, Indonesia and Singapore. Difficulties in obtaining gravid females for spawning, and shortages of suitable cheap food for the larvae are problems awaiting solution.

Brackish/freshwater prawns - Macrobrachium - The culture of the giant prawn Macrobrachium rosenbergii is in its early stage of development but has already shown great promise. The techniques developed in Penang, Malaysia, for rearing larvae to juveniles and for culturing juveniles to marketable size have been introduced to many countries and are being used as a basis for conducting experiments in Thailand, Indonesia, Singapore, Philippines and Vietnam.

Large-scale production of juveniles under controlled conditions is underway in Malaysia and Thailand, and to some extent in Singapore. Experiments on culturing juveniles to marketable size - either alone or in combination with non-carnivorous fish - are being conducted in Malaysia, Thailand and Singapore. Pilot scale commercial production of marketable sized prawn is in operation in Malaysia and Singapore.

Area and scope

The estimated areas of ponds and impoundments already used for some kind of shrimp farming, and areas having potentials for shrimp farming development, are shown in Table 4.

Species suitable for farming

Species suited for large-scale shrimp farming in the countries of the South China Sea region are: Penaeus monodon, P. merguiensis, P. indicus, Metapenaeus ensis and Macrobrachium rosenbergii.

Production rates

Estimated present production rates and those expected in the future after proper improvement and development, are shown in Table 5.

Economy of shrimp farming

Important items of shrimp farming production costs are feeds, seeds, and labour. Shrimp food includes natural food organisms that are produced in the ponds, or artificial food introduced into the pond. Shrimp farming operations that depend solely or mostly on natural food have low costs of production and low yields per unit area. Modern methods are able to produce over 2 500 kg/ha/ann, but the cost of production is often higher than U.S.$ 6.00 per kg.

Problems of shrimp farming development

Shrimp farming is still at an early stage of development. Important technological problems that require concerted, intensive experimentation are:-

1. The biology and habits of culturable species: Their environmental and nutritional requirements, growth rates, age of maturity, spawning habits.

2. Availability and supply of stocking material: From natural grounds - occurrence (seasonal, locality, abundance), collection (gear and methods), handling and transportation (equipment and methods); production under controlled conditions - availability of gravid females (season and locality of occurrence, methods of collection and transportation, production of gravid females under controlled conditions), spawning and hatching of eggs (equipment and methods), rearing of larval and juvenile stages (equipment and methods, food and feeding, management of pond and water conditions, reduction of mortality rates, control of enemies and diseases).

3. Culturing of juveniles to marketable size: Pond and water conditions and their maintenance, stocking rates and maintenance of optimum population densities, food and feeding, control of enemies and diseases.

4. Availability and supply of feed: Natural food organisms (development of methods for increase of production); artificial feeds (development and production of inexpensive formulated feeds).

5. Harvesting: Best season and optimum size of shrimp to harvest, gear and methods, handling and transportation of live specimens, preservation and storaging.

6. Engineering: Selection of sites, studies of topography, determination of sizes and numbers of ponds, design of shrimp farms (including water supply and drainage systems in relation to the physical environmental conditions), construction and maintenance of farms.

Many of the items listed above require careful experimentation under local conditions as a basis for conducting pilot scale trials prior to initiating large-scale commercial operations.

Crabs

(1) Mangrove crab (Scylla serrata)

Experiments to rear larval stages to juveniles have been conducted in Malaysia, Thailand and the Philippines, with varying degrees of success. This technique is not ready for practical application.

Raising of young to marketable size is being done on a small scale in Singapore, the Philippines, Thailand, Hong Kong and Malaysia. Emphasis is on the fattening of “green crabs” (females with immature ovaries) to promote development of ovaries to full size. These are highly esteemed, and bring a high price in the local market.

(2) Swimming crab (Neptunus pelagicus)

Experiments on the rearing of larval stages and the production of juveniles are being conducted in the Philippines and Thailand.

2.2.3 Molluscs

In every country of this region some species of molluscs are being cultured. The methods used are mainly traditional, and modern technology is of recent introduction. Important molluscs cultured are cockles, clams, mussels, oysters and pearl oysters.

Area and scope

Estimates of area of mollusc farms, and potential areas, are given in Table 6.

It can be seen from the above table that the total acreage already developed for mollusc farming is not big, but that the area having potential for future development is very great. Important factors limiting expansion are small market demand and water pollution.

Culture practices:

Cockles

Farming of cockles, Anadara, was started in China before the 17th century, along the south and east China coasts; it was introduced to the South China Sea region after the second world war. Cockles are extensively cultured in Thailand and Malaysia, and this activity is gaining importance in Indonesia, the Philippines and Vietnam.

The principal species cultured is Anadara granosa. It occurs naturally in many estuarine and coastal mudflats, and is able to thrive in waters with a range of salinity of about 20 to 31 percent. It feeds on phytoplankton by filtration, and has a fast growth rate.

Culture management consists of five main aspects: (1) collection of seeds, (2) preparation of culture beds, (3) sowing of seeds, (4) maintenance of beds, and (5) harvesting.

Cockle farming is a profitable enterprise. The operation is simple, requiring inexpensive gears. Neither fertilizer nor supplemental feeding are required. Small farms of about 20 ha can be managed by 3–4 persons, while large ones of about 130–150 ha need only about 12 labourers.

Problems

1. Water pollution is rapidly becoming a very serious factor limiting the expansion and development of cockle farming. It has caused slow growth, high mortality and low reproduction. It has also caused spreading of dangerous diseases to consumers, since cockles are often eaten partially cooked.

2. The present production of cockles from culture farms and natural beds is already able to satisfy the domestic markets fairly well, so that unless domestic and foreign market demand is increased or new processing methods are developed, the scope for expansion and development will be limited.

3. The availability of cockle seeds is a problem, and will be especially so for new culture farms.

Mussels

Mussels, Mytilus smaragdinus and M. sp., occur abundantly in most of the shallow coastal and estuarine waters of this region. They occur attached to the submerged portions of wooden and bamboo poles of the stationary fish traps. They are very efficient phytoplankton feeders, grow fast, reproduce rapidly, and are able to stand rough handling. The annual production is high, about 45 000 tons in Thailand alone. Among the molluscs, the mussel is considered to have the highest potential for farming development.

Some simple mussel farming operations have already been started in Thailand and the Philippines. Experiments on modern mussel culture and research on the life history of this bivalve has been initiated in Thailand, Singapore and the Philippines.

The main problems confronting existing operations and future development are similar to those of cockle farming: water pollution and markets.

Oysters

The main source of oysters in this region is the natural beds. While traditional types of oyster culture have been practised for over 100 years, modern farming techniques were introduced during the early 1950s.

The principal species cultured are Crassostrea gigas, C. malabonensis, C. iredalei, C. cuculata, C. lugubris, C. belcheri and C. commercialis.

Modern oyster farming in this region is still at an early stage of development. At present the total acreage of oyster farms is small, in the order of 4 500 ha, mostly in Hong Kong, the Philippines and Thailand. However, by conservative estimate over 200 000 ha of coastal areas have high potential for oyster farming development.

Farming activities are mostly similar to those of other regions: (1) collection of spat -determination of locality, time, and level of water for spat collection; selection, preparation and setting up of spat collectors; (2) growing of spat to marketable size - selection and preparation of oyster beds for growing and fattening, setting up of collectors with spats (on rafts, lines, etc.), and sometimes shifting of oysters to final fattening grounds; (3) harvesting and marketing.

Problems confronting development of oyster farming are similar to those of cockles and mussel farming - the increasing effect of pollution, and the difficulties in finding markets.

Pearl oysters

Pearl culture was introduced to this region after the second world war, and is now practised in Hong Kong, Malaysia, the Philippines, Thailand and Indonesia. The species of pearl oysters used include Pictada martensii, P. margaritifera, and P. maxima. The culture operations are based entirely on the techniques developed in Japan, in several cases employing Japanese technicians and in collaboration with Japanese companies.

Main problems are difficulties in obtaining mother pearl oysters, lack of skill in producing pearls, and getting a good market price.

2.2.4 Algae

Various species of seaweeds have been used by people of this region for centuries, as food and for medicinal and industrial purposes. Sources have been local natural beds and importations. Farming of seaweeds is a recent activity and is still in the early development stages.

The species being experimented with are: Eucheuma spinosum, E. edule, Porphyra sp., Gracilaria spp., Gelidium sp., the first of these has shown very high potential for development. Eucheuma spinosum is a red alga, growing naturally on rocks, coral reefs and sandy bottoms of intertidal or subtidal zones where the water is clear, fast moving and the salinity is over 32‰. It is eaten raw as salad, and as material for the extraction of carrageenin, a valuable substance used in the manufacture of products that required gelling, suspending, thickening or water-holding properties (paints, cosmetics, textiles, ice-cream, etc.). Experiments on the farming of this species have produced very encouraging results in the Philippines, Singapore and Indonesia.

Porphyra (laver) culture technique developed in Japan has been introduced in the Philippines on an experimental basis with encouraging results. Trials on production of monospores from the conchorcelis stage will be started soon. The laver is cultured on rope-nets; the spores are collected from nature.

Problems of development of seaweed culture are: (1) lack of farming tradition, (2) lack of technical know-how and experienced technicians, (3) climatic limitations, and (4) pollution of coastal waters.

2.3 Status by country

2.3.1 Indonesia

Indonesia is well known for the extensive development of aquaculture, in both fresh and brackish waters. The long history (over 400 years) and huge area (over 180 000 ha) of milk-fish ponds make Indonesia the leading country of the world in brackishwater fish culture.

Area and scope

Based on 1971 records it has been estimated that Indonesia has about 184 000 ha of brackishwater fishponds. All of them are producing milkfish as the principal crop, and many of them are producing shrimps as a secondary crop. Of these ponds at least 100 000 ha could be improved to increase their production of fish and shrimp, and about 20 000 ha could be developed into highly productive modern shrimp farms.

In addition to the existing ponds there are enormous acreages of estuarine, coastal and mangrove areas, coastal flats and shallow coastal waters in Sumatra, Kalimantan, Sulawesi, West Irian, in the order of 6 million ha (Pillay 1973). Of this area it has been estimated that at least 600 000 ha have high potentials for coastal aquaculture development: 390 000 ha for fish and fish-cum-shrimp; 100 000 ha for shrimps, and 110 000 ha for other aquaculture practices.

Yield and production

The total annual production from these brackishwater ponds has been estimated to be about 60 000 metric tons of fish plus 3 500 metric tons of shrimps, or an average production of about 350 kg of fish and 20 kg of shrimps per hectare per year.

With improvement of culture technique the present yield and production rates could be increased by 200 to 300 percent.

If an additional 100 000 ha were developed for milkfish and 50 000 ha for shrimp, and if modern efficient farming methods were adopted, a total annual production of 100 000 metric tons of milkfish and 50 000 metric tons of shrimp could be expected.

Species cultured

Culture practices

Milkfish is the principal species cultured, with shrimp as a subsidiary crop. The culture method and management have been described in detail by Schuster (1952) and others.

Some of the milkfish ponds have been converted into shrimp ponds, for shrimp farming alone. This operation is similar to the traditional trapping-holding-growing method practised in Singapore, and produces an average yield of 200–400 kg/ha/ann.

Controlled stocking has also been introduced but is still in an experimental stage. The species used is Penaeus monodon. The post-larvae of this species are known to occur abundantly in many coastal areas of the country, and can be collected without much difficulty. The potential of annual production of post-larvae from natural sources has been estimated to be about 15 million.

The UNDP/SF project on Brackishwater Shrimp and Milkfish Culture Applied Research and Training is now engaged in research to develop efficient methods for shrimp farming on a large commercial scale.

Research

Most of the research on coastal aquaculture is being conducted at the: (1) Inland Fisheries Research Institute, Bogor, (2) Marine Fishery Research Institute, Djakarta, and their field stations, and (3) the recently established Indonesian/FAO/UNDP research and training centre, Djapara.

Problems

1. Due to the increasing industrialization, the harmful effects of water pollution on coastal aquaculture development will become progressively worse.

2. Difficulties in transportation prevent efficient shipping of coastal aquaculture products from places of production to markets.

3. Increasing difficulties in getting supplies of stocking material from natural sources; efficient methods for the production of quality stocking material under controlled conditions are still under experimentation.

4. Insufficient knowledge on the life and habits of the species cultured.

5. Shortage of technical personnel at all levels.

6. Lack of adequate financial resources for capital investment and operating costs.

2.3.2 Khmer Republic

Fish culture in the Republic of Khmer is not well developed. Apart from a few fresh-water farms near Phnom-Penh, fish farming is being done almost entirely in floating cages or per a set along the edges of rivers. Coastal aquaculture has not been practised.

It has been estimated that there are over 50 000 ha of estuarine areas, mangrove swamps and coastal flats suitable for coastal aquaculture, but none have been properly developed for this purpose. Fisheries production in these rich areas still depends on capture.

Most of the high quality culturable species that occur in Thailand and Vietnam also occur in Khmer. Some of the species that could become of major importance in future development are: finfish - Chanos chanos, Mugil sp., Lates calcarifer; crustaceans - Penaeus monodon, P. merguiensis, P. indicus, Metapenaeus ensis, Macrobrachium rosenbergii, Scylla serrata; molluscs - Anadara granosa, Mytilus sp.

The huge fertile brackish and coastal areas of Khmer have very high potential for coastal aquaculture development. This could become a very important economic asset to the national economy, and should be given priority consideration in post-war reconstruction and development programmes. If only one-fifth of the 50 000 ha of potential areas were developed, with an average production of 1 000 kg of fish and shrimp/ha/ann, an annual production of 10 000 metric tons of high priced fish and shrimp, worth over U.S.$ 10 million, could be produced.

The main problems are: (1) lack of coastal aquaculture tradition, (2) lack of technical know-how, and management skill and experience, (3) lack of technical personnel of all grades, and (4) lack of financial resources.

2.3.3 Malaysia

Coastal aquaculture in Malaysia is still at an early stage of development. It was started after the second world war in Panchor village in Perak, with experiments on cockle farming. Since then cockle farming has spread rapidly throughout the west coast of West Malaysia. Pearl culture, prawn farming and milkfish culture are of recent introduction. In spite of her short history in coastal aquaculture development, Malaysia has gained considerable prominence for the important research conducted at the Marine Fisheries Research Institute, Penang, on the life history, rearing of larvae and culture of adults of the giant freshwater prawn, Macrobrachium rosenbergii.

Area and scope

Malaysia has very extensive brackishwater areas, mangrove swamps, and coastal flats, of which at least 150 000 ha are suitable for aquaculture development. Of these only about 4 000 ha are being used for this purpose. Aquaculture is operated on a limited scale, with cockle farming as the most important, prawns next, and fish the least.

The potential and scope for future development is extremely great, especially for prawns (both penaeids and Macrobrachium), and to some extent for finfish farming also. There are over 120 000 ha of brackishwater areas suitable for fish and prawn farming development.

Species suitable for culture

High quality species available for aquaculture development in Malaysia are:

Culture practices

Milkfish - Some 85 000 ha of brackishwater area in East and West Malaysia have potential for development of milkfish farming (and for prawn farming). Of these only about 20 ha (in Sabah) have been used.

The seeds are collected from natural grounds, in the vicinity of the farm, using simple hand nets. Culture management is still primitive; stocking is of a single size group, with total harvesting at the end of each culture period. The annual yield is about 9 tons, with an average of about 450 kg/ha/ann.

Milkfish is regarded as a second grade fish in East Malaysia, and is unknown in West Malaysia. Farming of this fish is at a very early stage of development. An experimental brackishwater fish culture station will be established in Johore State, West Malaysia, and a demonstration station near Kota Kinabalu, East Malaysia.

Prawns - There are about 400 ha of brackishwater ponds in Johore, West Malaysia, and some 100 ha in East Malaysia being operated as prawn ponds (Singapore type). A very conservative estimate is that over 50 000 ha of extensive estuarine and mangrove areas have high potential for prawn farming (also fish farming) development.

Most of the existing brackish prawn ponds are constructed and operated according to the Singapore style (described in greater detail under “Singapore”). Macrobrachium culture is still in the experimental stage; these prawns are cultured either with non-carnivorous fish or alone.

The annual production of marine prawns is about 300 tons, with an average yield of about 600 kg/ha/ann. No record is available for total production of Macrobrachium, but an average yield of 200–250 kg/ha/ann has been obtained in addition to the normal yield of about 1 ton of fish.

The source of seed for marine prawns is from the natural habitat. For Macrobrachium hatcheries at Penang and Kuchin (Sarawak) are producing juvenile prawns for experimental purposes as well as for distribution to prawn farmers.

Problems

1. Shortage of technical personnel and funds for conducting experiments on:

   1. production of juveniles,
   2. efficient methods for raising juveniles to marketable size,
   3. control of pond conditions favourable to the life and growth of prawns, and
   4. control of enemies, etc.
   
   

2. Lack of experienced extension officers.

3. Lack of financial resource to meet the high cost of construction of ponds and costs of operation.

4. Difficulties in obtaining supply of gravid penaeid prawns for spawning.

Cockles - There are about 2 000 ha of cockle farms, mostly in West Malaysia, and some in East Malaysia. Over 10 000 ha of coastal flats suitable for cockle farming are available for the expansion of this industry, should the demand increase.

The average yield is about 14 mt/ha/ann; the total annual production is about 27 700 tons.

All cockle seeds are collected from natural beds, mainly in the Perak and Penang areas, during two seasons: from October to December in Penang and February to March in Perak. The natural seed beds are not stable; they tend to fluctuate widely in seed abundance, and even shift from locality to locality.

Problems - The present market is saturated, and new markets for raw cockles need to be found or new products developed.

Pearl oysters - Over 16 000 ha of coastal waters (10 000 ha in East Malaysia and 6 000 ha in West Malaysia) could be used for oyster, mussel and pearl oyster culture. Of this area, about 870 ha in Sabah are being developed into a pearl culture farm. This operation is a joint venture between Malaysians and Japanese, under the technical management of the Japanese.

The pearl oysters are obtained from natural grounds. The total annual production is about 40 000 pearls (mainly half-round-pearls), with an average yield of about 45 pearls/ha/ann.

The main problems are: (1) extreme difficulties the Malaysians encounter in learning the techniques from the Japanese, (2) shortage of pearl oysters, and (3) high mortality of oysters caused by illegal fishing with explosives.

Research

Research in coastal aquaculture made its true beginning in 1959 when the Marine Fisheries Research Institute was established. Since then nearly all the research has been conducted either at this Institute or using the Institute as the base of operations. In the beginning the research programme included studies on the biology, life history, breeding habits, and breeding technique of the cockles, Anadara granosa, the freshwater prawn, Macrobrachium rosenbergii, and the mangrove crab, Scylla serrata; some breeding experiments on the marine prawns, Penaeus monodon, P. merguensis and Metapenaeus ensis, have also been conducted.

At present the main emphasis of research is on Macrobrachium rosenbergii - the production of juveniles and their culture to marketable size, either alone or in combination with non-carnivorous fish. A new set of breeding tanks, some as large as 200 tons capacity, has been constructed at the Institute. Experiments are being carried out to increase survival and growth rates of larvae and juveniles, including the use of manufactured formulated feeds.

Some preliminary experiments and observations have been initiated at the Institute on the life habits, feeding and growth of Lates calcarifer, Mugil sp. and Epinephelus sp., all of which have potentials for farming.

With the technical assistance of FAO a plan for the establishment of a coastal aquaculture research and demonstration station has been prepared for the Malaysian Government. A suitable plot of land about 100 ha in area at Gelang Patah, Johore, has been selected as the site of this station. The main items of research will include the development of practical techniques for the various phases of farming of mullet, milkfish and prawns (Penaeus monodon, Metapenaeus ensis, and Macrobrachium rosenbergii).

In addition to research, this proposed station will also serve as a centre for training aquaculture technical personnel of all grades, as well as a centre of extension and demonstration.

Training

There is no school specialized for the training of aquaculturists, but courses in fish culture have been conducted at the Agriculture College and at the University of Malaya, and courses in coastal aquaculture are expected to be conducted at the University of Science in Penang.

The present aquaculturists are from: (1) home university graduates having some special training abroad, (2) graduates of the fisheries training course at the University of Singapore, and (3) graduates from universities abroad.

2.3.4 Philippines

Aquaculture in the Philippines has a history of over 400 years. Coastal-brackishwater fish farming has been the principal activity. According to the 1971 records of the Philippines Bureau of Fisheries, coastal aquaculture in the Philippines covered a total area of about 4 000 hectares, had an investment of more than 332 million pesos, employed more than 166 000 persons, and had an annual production of about 98 000 metric tons of fish and shellfish, valued at about 328 million pesos. The industry provides an important source of animal protein food and valuable items for export for foreign exchange.

Since the end of the second world war, coastal aquaculture has attracted a great deal of attention from Government and private sectors, and programmes for the improvement of the existing practices, and development of new areas and new practices, have been included among the high priority national economic development projects. Large loans from the World Bank have been approved for aquaculture development, and implementation is expected shortly.

Area and scope

It has been estimated that about 174 000 ha are used for various coastal aquaculture operations. Among the huge acreage of mangrove swamps, estuarine areas, tidal flats and shallow shore areas, there are at least 550 000 ha suitable for future development (Table 7).

The present average production of fish plus shrimps is about 500 kg/ha/ann, which could be increased to 1 000 kg/ha/ann with improvement in techniques. The total acreage of the existing farms and of potential areas is about 724 000 ha, with a total potential capacity of about 724 000 metric tons of fish and shrimps, worth more than U.S.$ 360 million.

Species cultured or culturable

Milkfish is the principal finfish species raised. Culture of eels and mullets has already been tried and has shown encouraging prospects. Other fish include Siganus, Epinephelus, Lates, Scatophagus. The most important crustacean species is Penaeus monodon, followed by P. merguiensis, P. semisulcatus, P. indicus and Metapenaeus monoceros; Macrobrachium rosenbergii has a great potential. The mangrove crab, Scylla serrata, and the blue crab Neptunus pelagicus, also have good prospects.

The oysters cultured are Crassostrea malabonensis, C. iredalei, C. palmipes and C. cuculata; there is only one important species of mussel, Mytilus smaragdinus; and one of cockle, Anadara granosa. Eucheuma spinosum has high potential for development among the algae, followed by species of Gracilaria, Gelidium and Porphyra.

Culture practices

Milkfish - Chanos chanos is a euryhaline species that spawns in the open sea and around some islands, from April to late August. Sexually mature specimens have never been observed among the cultured fish. Induced spawning by mature specimen caught in the sea has not yet been successful. All fry and fingerlings used for culture are collected from fry grounds along the coastal areas. The annual catch of fry is in the order of 4 000 million. The fry are either sold to the pond operators directly or are cultured in nursery ponds until they are fingerlings of 4–6 cm, then they are sold for stocking.

In addition to culture in brackishwater ponds, a new method has been started at the Laguna Lake for the farming of the milkfish in pens and in marginal areas of lakes partitioned with nylon netting. This operation has proven to be highly productive and profitable, and is expanding rapidly.

Shrimp - Nearly all the brackishwater ponds produce some shrimps. Stocking is mainly by natural processes: larvae and juveniles of several species of shrimps enter the ponds with the inflow of water during high tides. The average production, in addition to fish, is about 20–100 kg/ha/ann.

Some progressive pond operators are doing supplementary stocking with collected juveniles of Penaeus monodon. In such cases a higher production of shrimp, 150–200 kg/ha/ann, has been achieved.

Some of the brackishwater ponds have been converted to shrimp culture alone. Stocking may either be by natural processes, or by controlled stocking or both. The yield per hectare varies from about 100 to 500 kg/ha/ann.

Sugpo (P. monodon) juveniles are collected from estuarine areas, lagoons, bayous, tidal creeks, seawater supply canals of brackishwater pond systems, etc., and are sold to farmers for stocking. The life history of P. monodon is known, and spawning and roaring of larval stages to juveniles have been successfully done in the laboratory. However, mass production of sugpo for commercial farming is still at an early stage of experiment and development.

The prawn, Macrobrachium rosenbergii, occurs in many of the large rivers and their estuarine areas. It has great potential for farming development, and could become as important as the farming of penaeid shrimps, if not more so.

Crabs - Experiments and small pilot scale farming of crabs has produced good results, and there is a good potential for its development.

Oysters and mussels - The farming of molluscs was started at the beginning of the present century, and through several decades of gradual development plus the introduction of modern cultural methods after the second world war, has developed into the present profitable industry, covering more than 3 500 ha. Oysters are the principal molluscs cultured, followed by mussels, cockles, and Paphia. Some pearl oyster farms are also in operation. Modern methods of oyster culture are being used and the industry is expanding rapidly. Mussel culture is gaining popularity, but modern cultural methods have not yet been introduced. Mussels are able to reproduce and grow very fast in Philippine waters, and they have a very great potential for large-scale farming, for producing large quantities of cheap animal protein food for the people, and as animal feed.

Algae - Culture of seaweed has made a good start and is progressing steadily. The principal species used is Eucheuma spinosum. The culture of Gracilaria, Gelidium, Porphyra, Caulerpa, and Gelidiella are in the early stages of experiment and development.

Training

The College of Fisheries, University of the Philippines, and the College of Fisheries of the Mindanao State University are offering undergraduate and graduate courses in aquaculture, including coastal aquaculture. The Philippine Bureau of Fisheries has conducted in-service training courses in milkfish and shrimp culture for its junior fishery biologists and aquaculture extension officers. The Agriculture and Fisheries Loan and Extension Section of the Development Bank of the Philippines has also conducted a series of training courses on aquaculture for their extension technical assistants. The new Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC) is expected to conduct a series of training courses on coastal aquaculture in general and on shrimp culture in particular in the near future.

Research

Important research on aquaculture is being conducted by the College of Fisheries of the University of Philippines, the College of Fisheries of the Mindanao State University, the bilateral aid programme on the research and development of aquaculture (USAID and University of the Philippines), the Fisheries Section of the Laguna Lake Development Authority, and some private agencies and associations. The Department of Aquaculture of SEAFDEC is expected to conduct research on shrimp farming and related subjects.

Problems

Among the numerous problems confronting the improvement and development of coastal aquaculture in the Philippines, the principal ones are:

1. Shortage of technical personnel of all grades - from pond operators to research aquaculturists.

2. Lack of basic knowledge of the biology, habits, and environmental requirements of the cultured or culturable species, under local conditions.

3. Difficulties in getting sufficient quantity of stocking material from natural sources.

4. Lack of technical skills and facilities for the production of quality seeds.

5. Lack of technical skills in cultural techniques and operations.

6. Lack of financial resource for capital investment and operating costs.

7. Water pollution problems; these are increasing rapidly in intensity and are spreading to new areas.

2.3.5 Singapore

Fish culture in Singapore has a long history. It was started by Chinese immigrants, using mainly Chinese major carps. Caostal aquaculture, however, apart from the prawn pond operations, has not been practised on an organized industrial scale. The culture of finfish, giant prawns, oysters and mussels is only at early experimental stages.

Area and scope

During recent years the rapid development of this small island nation toward industrialization, and the urgent need for increasing housing projects, made it necessary to make full use of all available land. Because of this many of the existing fish and shrimp ponds were filled or reclaimed. There remains a total of about 1 500 ha - 1 000 ha of freshwater ponds for finfish and 500 ha of saltwater ponds for shrimp. This small acreage of ponds could be a great asset to the economic development of the country if intensive culture is practised, with emphasis on species of high market price.

The possibilities of using the shallow water areas around Singapore and the islands for farming of mussels, oysters and seaweeds are being explored. There are strong indications that there is substantial potential for the development of mussel farming.

Species cultured

Among the finfish Epinephelus sp., Lates calcarifer and Siganus sp. are in experimental stages. The crustaceans cultured include Penaeus merguiensis, P. indicus, P. semisulcatus, Metapanaeus ensis, M. burkenroadi, M. brevicornis, M. monoceros in prawn ponds; Macrobrachium rosenbergii is at the experimental and pilot stage; Scylla serrata (the mangrove crab) is cultured on a small scale. The molluscs cultured are Mytilus smaragdinus and Crassostrea cuculata, both experimentally. The alga Eucheuma spinosum is cultured experimentally as well.

Culture practices

Singapore has about 600 ha of shrimp ponds, about half on Singapore island and the rest on neighbouring islands - 180 ha in Ponggol, 120 ha in Pulan Ubin, and 50 ha in Pulan Tekong. These are trapping-holding-growing operations. The ponds are created by the construction of strong dykes around swamp land partially cleared of mangrove trees.

Stocking of the ponds depends entirely on natural processes. The sluice gates are opened during every high tide, allowing young prawns and young fish to enter the pond with the rush of inflowing water. Wire screens are then placed across the sluice gates to prevent escape of prawns with the receding tide. The prawn larvae and young prawns feed readily on the rich food organisms produced in the pond, grow fast, and are big enough for harvesting in about 4–6 months.

Natural stocking is simple but is able to use only a fraction of the high productive potential of such ponds. The natural supply of prawn larvae and young prawns fluctuates widely in quantity and in species composition from time to time, and thus it is impossible to control and maintain the density and ratio of the prawn population at optimum levels. Many of the fish that enter the pond are predators, preying heavily on the prawns. Because of these factors the average production of these ponds is only about 250–400 kg/ha/ann, while the potential productive capacity has been estimated to be about 600 kg/ha/ann without supplemental feeding, and as high as 2 000–2 500 kg/ha/ann when properly developed and managed, with controlled stocking and intensive feeding.

The degree of success of existing traditional prawn pond operations depends a great deal on knowledge and experience in: (1) the selection of suitable sites for the construction of ponds - location, elevation, nature of soil, tidal range, salinity range and fluctuation, occurrence of larvae and young prawn of commercially valuable species, etc., (2) the design, construction and management of ponds and of water sluice gates, (3) controlling the inflow and outflow of water and the maintenance of water level, (4) the prevention and control of predators, and (5) harvesting.

Experiments on Macrobrachium culture were started in 1970, at the Sembawang Fish Culture Station of the Primary Production Department, with about half a dozen berried female prawns imported from Penang, Malaysia. Experiments on spawning and rearing of larval stages have been successfully carried out and a stock of mature prawns has been produced and maintained for propagation.

With the juveniles produced by the Aquaculture Unit of the Primary Production Department, experiments on culturing this prawn in ponds - either alone or together with non-carnivorous fish - have been conducted in cooperation with Chinese carp farmers. The results obtained were very encouraging and enthusiasm for farming of this prawn has increased very rapidly. It could become a profitable industry in the near future.

The culture of the mangrove crab is done on small scale in brackishwater ponds of about 0.2 to 1.0 ha in size. The water is clear; salinity about 15–25 percent; depth about 0.5 to 2.0 metres, subjected to daily tidal fluctuations.

The culture practice is in reality a fattening operation. Young or lean “green crabs” are bought very cheaply from collectors and released into the ponds. They are fed daily with trash fish and within a few weeks grow fat. The emphasis is on the fattening of lean female crabs to develop their ovaries fully. These are highly esteemed as luxury food, and command high prices in local markets.

Research

The principal research on coastal aquaculture in Singapore includes:

Training

The Fisheries Biology Unit of the Department of Zoology, University of Singapore, has been functioning as a training and research centre in aquaculture as a whole, and in coastal aquaculture in particular. It has a Diploma Course (equivalent to undergraduate) and a post-graduate course. It has trained aquaculturists not only for Singapore but also for Malaysia and some other neighbouring countries.

Problems

1. Many gaps exist in the knowledge of the life history and ecology of the culturable species.

2. There are difficulties in obtaining supplies of quality stocking material, and methods and facilities for the production of stocking material need to be developed.

3. Efficient methods for commercial scale intensive aquaculture operations have not been developed.

4. There is lack of space for expansion.

5. The effects of water pollution are becoming increasingly worse.

2.3.6 Thailand

Fish culture in inland waters has been extensively practised in Thailand for many decades. Coastal aquaculture, however, is of more recent development, having a history of less than 50 years.

The Thais are great lovers of seafood. Many kinds of clams, mussels, oysters, crabs and fish are caught from estuarine and coastal areas by thousands of people. From the collection of shellfish from their natural beds, mussel and cockle farming has evolved, and the trapping of shrimp in the salt pens during the rainy season has gradually developed into the present shrimp farming.

After the second world war, the rapid increase in the demand for protein food for the people has prompted the Government and the public to initiate various projects resulting in the expansion and development of coastal aquaculture practices.

Area and scope

The total acreage under coastal aquaculture in Thailand is approximately 10 000 ha, which represents only about 1/15 of the areas having rich potential for future development. It has been roughly estimated that along the coastline (about 1 500 km on the Gulf and 900 km facing the Indian Ocean) there are over 1 million ha of productive estuarine areas, mangrove swamps and coastal flats, of which over 150 000 ha are suitable for aquaculture development. A breakdown of the important types of existing coastal aquaculture practices and their potentials for future development are given in Table 8.

Yield and productivity

Records of yield and productivity of cultured and natural production are often difficult to separate; data given in Table 9 are estimates.

Source: Sribhibhadh 1972

Species cultured

Among the many culturable species those suitable for large-scale commercial farming development are:- finfish: Mugil spp., Lates calcarifer, Anguilla sp., Chanos chanos; crustaceans: Penaeus merguiensis, P. monodon, P. semisulcatus, Metapenaeus monoceros, Macrobrachium rosenbergii, Scylla serrata; molluscs: Anadara granosa, Mytilus smaragdinus, Crassostrea commercialis.

Culture practices

In comparison with the extensively practised fish culture in inland waters, farming of finfish in brackish and coastal waters is at an early stage of development and is on a small scale. The species used are milkfish, sea-bass and mullet.

Milkfish fry and fingerlings occur in fairly large numbers in shallow coastal waters, river mouths and mangrove swamps along both coasts of the Gulf. The fry collection season is from April to July, with the peak period in May. At present the demand for fry is small, and an annual catch of less than 500 000 is sufficient to satisfy the requirement. A much larger quantity of fry can be collected should the demand increase.

The total area of milkfish ponds is about 230 ha; of these about 10 ha are used as nursery ponds for rearing fry and fingerlings, and the rest for growing table fish. Culture management is simple and traditional; it is based on single stocking and complete harvesting, using small amounts of fertilizers and little supplementary feeding. The stocking rate ranges from 2 000 to 4 000 fingerlings per ha. The growing period is 4–5 months. The yield is low, with an average of only 560 kg/ha/ann.

Young sea-bass of 20–30 cm size are collected from estuarine areas for culturing in ponds, partitioned water canals or water ditches of plantations. The salinity of water ranges widely, from about 1 to 20‰. The stocking rate is about 1 000 per ha. The fish are fed daily with small trash fish. The growth rate varies in accordance with the quality and quantity of supplemental feeds given. Normally the young stocked fish grow to table size in 12–18 months. The average yield is low, estimated at 400 kg/ha/ann, but since the market price of this fish is high the operation is profitable.

Mullet culture experiments are now being conducted at government experimental stations and in private fish farms. Many of the milkfish farmers are also experimenting with mullet culture. The prospects for mullet culture development are fairly bright.

The type of shrimp farming practised in Thailand is a simple and traditional “trapping-holding-growing” operation. It was started around 1930 at the coastal mangrove areas of the inner Gulf, in the vicinity of the mouth of the Chao Phyra River; since then it has spread to several other coastal provinces, covering a total area of about 8 000 ha.

The early shrimp farms were mostly converted from salt pens, but recent ones are constructed in mangrove swamp areas. The main structures are the bunds, water gates, and water supply and drainage canals.

The stocking material - post-larvae and juveniles - are all from natural stock. They enter the impounded area with the incoming water, either by natural flow during high tide or through pumping. They are held in the pond to grow for a period of 3–4 months before being harvested. Partial harvesting is done with traps set in the ponds, or with castnets. Total harvesting is done by draining the pond and catching the outgoing shrimps with nets set at the water control gates. This culture operation can be repeated as long as brackishwater and shrimp seeds are available. In some rich areas four or more crops of shrimps can be produced in one year.

Modern shrimp farming is expected to be developed in Thailand in about five years, with Japanese technical and financial assistance.

Farming of the giant prawn, Macrobrachium rosenbergii, is at an early stage of development, but has already shown very great potential and scope for future development. Experiments and pilot scale operations on the production of prawn juveniles are being conducted fairly successfully at the fisheries stations at Songkhla and Bangkhen. The present production capacity of about 1 million juveniles a year can easily be increased when more are needed. The small private prawn hatcheries have been started recently and both are already able to produce some juveniles.

Experiments on culturing this prawn in ponds, either alone or in combination with non-carnivorous fish, are being conducted at several fisheries stations. A national project for the development of prawn farming has been approved by the government, and a suitable site is expected to be selected soon for the establishment of an experimental station.

The farming of the mangrove crab, Scylla serrata, is in an experimental stage, conducted at the marine and brackishwater fisheries stations of the Fisheries Department. The progress of work has been slow. Studies on the life history, and experiments on rearing the larvae of this crab are being conducted by the Marine Science group of Chulalongkorn University.

The cockle, Anadara granosa, is very extensively cultured and is in great demand by the Thais. It occurs in most of the shallow coastal flats all over the country. Culture beds are found mainly in the muddy intertidal flats along the inner Gulf.

The seeds are all collected from their natural beds, by professional collectors or by the cockle farmers themselves. They are transported to the cockle beds and scattered during high tide.

The culture period is 8–12 months, but harvesting can be done over a period of 1–2 months. Harvested cockles are washed in seawater, then packed in gunny bags for transportation to the market. They can be kept alive for several days under moist conditions. One or two days are allowed for the cockles to discharge their intestinal contents.

Cockles are usually consumed partially or very lightly cooked. The shells are cleaned and placed in a wire or bamboo basket and submerged in boiling water for less than one minute, just long enough to paralize the abductor and abductor mussels. The shells can then be opened without much effort and the lightly cooked meat is eaten with a special sauce. It is also used for making stews, curries, etc. Dried and canned cockles have also been produced for domestic and foreign markets.

The major sources of supply of mussels are from the thousands of poles of the stake fish traps, and from other natural substrata. With the decreasing numbers of fish traps, planting of poles to grow mussels was started, and this led to the development of mussel culture.

Bamboo poles are planted in shallow coastal areas where the depth is about 5–10 metres. These poles are planted about 1 metre apart, in rows. Spat are collected on these poles from December to March. The young mussels grown from the early spats are usually harvested as duck feed, when they are about 2 months old. Feeding on the rich phytoplankton of the Gulf, mussels grow rapidly and are able to attain marketable size and sexual maturity in 8–10 months.

Mussels are well liked and extensively consumed by the Thais, and they represent one of the cheapest animal protein foods. During the peak harvesting season, large quantities of surplus mussels are used as duck feed. Substantial quantities of mussels have also been dried for domestic use especially in remote interior districts, and for foreign markets.

The most serious problem confronting the development of mussel farming is water pollution.

Of the half dozen or so common species of oysters in Thai waters, Crassostrea lugubris, C. belcheri and C. commercialis are the most important for farming.

Culture practices are still at an early stage of development, but several oyster farms are already operating successfully. The old practice of collecting young oysters from their natural beds and planting them in rich grounds to grow has been replaced or supplemented by planting and growing of collected spat. Material used as cultch for collecting spat include mangrove tree branches, bamboo, concrete blocks, corrugated tiles, oyster shells and stones. The growing period is 1–1½ years. Production from these farms is limited in amount, and is mainly sold to hotels and restaurants.

A fairly large pearl oyster farm was established a few years ago as a joint venture between Thai and Japanese private companies, with Japanese technicians. Details of the operation are not available but it is known to be successful.

Training

Courses in practical fish culture are offered at several agriculture vocational schools in the country. Unfortunately, due to the lack of trained instructors, graduates from these schools are not competent to do practical work. Some of the more progressive graduates continue their studies at universities while others take other jobs.

In-service training or refresher courses in aquaculture have been conducted by the Fisheries Department, for junior and medium grade fisheries officers, once or twice a year.

The College of Fisheries of the Kasetsart (Agriculture) University has a Fishculture Department, offering both undergraduate and graduate course. An average of 5–10 students in aquaculture are graduated each year; most of them are absorbed by the Thai Fisheries Department to serve as fisheries officers at the various experimental stations; some take up teaching or other professions, and very few are employed by the industry. About 80 percent of the technical staff of the Thai Fisheries Department are graduates of this University.

Courses in fishery biology and aquaculture are being offered by the Department of Zoology and Marine Sciences of this national university, to both undergraduate and post-graduate students. The training is academically oriented, aiming at producing technical personnel for research.

Many fisheries officers have been sent abroad for advanced training in various aspects of aquaculture. These government scholarships may be sponsored by UNDP/FAO or bilateral aid agencies. Up to the present a total of over 30 fisheries officers serving in the field of aquaculture have received training abroad.

Research

A large number of research projects in coastal aquaculture are being conducted at the various fisheries and biological experimental stations and laboratories of the Fisheries Department, Kasetsart University, Chulalongkorn University and the Thai/Danish Marine Biological Research Institute; at Bangchan, Rayong, Songkhla, Phuket, Samutsakorn, Suratthani, and Bangkhen.

A national project on the research and development of marine shrimp farming is being implemented with technical and financial assistance from Japan. A national project on the research and development of Macrobrachium farming has been planned by the Fisheries Department and is included in the country programme.

Problems

1. Lack of knowledge and experience in culture techniques.

2. Lack of knowledge on the life histories and habits of the important culturable species, and their environmental requirements.

3. Lack of skill and experience in the production of stocking material.

4. Lack of technical personnel of all levels.

5. Difficulties in obtaining low-interest loans to meet capital investment and operating costs.

6. There are good domestic and foreign markets for shrimps and prawns, but not necessarily for cockles and mussels. New markets must be found.

7. There are no cooperatives organized and operated for the benefit of the aquaculture farmers.

8. The harmful effect of the existing water pollution on coastal aquaculture will increase in intensity.

9. Some conflicts of interest in the use of coastal mangrove areas are to be anticipated, expecially with forest reserves, fish and shrimp nurseries, industrial development and agricultural development.

2.3.7 Hong Kong

Hong Kong has been well known, especially during 1930–1965, as the nursery and distribution centre for Chinese major carp fry and fingerlings. Young fry were imported from China and reared in special nursery ponds by experienced operators. Fingerlings were exported, especially to Taiwan Province, Thailand, Singapore and Malaysia. The importance of this industry has declined considerably since induced breeding of these fish has been successfully accomplished by many of these importing countries.

However, because of the high price of fresh fish, aquaculture operations in Hong Kong continue to be a profitable industry, in spite of limited land space, rapid industrialization and the high cost of production.

Area and scope

There has been a substantial increase in aquaculture operations in Hong Kong during the past eight years. The acreage of fishponds has increased from about 700 ha in 1966 to about 1 200 ha in 1973; the target is 1 600 hectares. Most of the new ponds are converted from paddy fields of low production or paddy fields located adjacent to tidal creeks.

The total area used for marine culture of finfish is small, probably only about 25 ha, while there are about 1 000 ha of coastal areas having possibilities for this purpose; some of these may also be developed for shrimp culture.

The present oyster beds occupy an area of about 2 000 ha. Another 5 000 ha or so of potential area for the expansion of oyster farming may be found along the coast of the New Territories and some of the islands under the jurisdiction of Hong Kong.

Species cultured

The finfish cultured include Mugil cephalus (on an extensive scale), Epinephelus altaara, E. awoara, E. brunneus (pilot scale), Mylio spp., Siganus sp., Chrysophrys sp., Evyunis sp., Lutjanus argentinaeulatus (on experimental or pilot scales). The oyster, Crassostrea gigas, is extensively cultured.

Culture practices

The grey mullet, Mugil cephalus, is mainly cultured in ponds in combination with Chinese major carps. It grows fast and is esteemed as a food fish in Hong Kong. It can be acclimatized to live in brackish or freshwaters, but it is known to grow best in slightly saline water - about 5–10‰.

Any pond that is suitable for Chinese carps can be used for culturing mullets. However, ponds that are located within easy reach of fresh and brackishwater are preferred.

All fry and fingerlings are collected from their natural habitats. Young fingerlings of about 2.5 to 3.5 cm occur, usually in small schools, from the end of January to the end of March along the coastal waters, especially where there is some discharge of freshwater containing sewage. The fingerlings are collected with fine-meshed handnets, scoopnets, liftnets and small seines, and are kept in open tins with brackishwater (mixture of half seawater and half freshwater) for transportation to pond area.

Fingerlings of three common species of mullets (Mugil cephalus, M. longimannus and M. troscheli) often occur together, but only those of M. cephalus are suitable for culture.

Stocking

Stocking of fingerlings is done from February to April. Transplanting of half-grown fish is done in autumn or early spring. The annual stocking rate of fingerlings of about 3 cm is as follows:

The fish are fed daily with about 2 500 kg of rice bran and 31 000 kg of peanut cake. The ponds are given repeated applications of animal manure and chemical fertilizers per ha per crop of fish, for a growing period of 300 days.

The 10 000 to 15 000 grey mullet fingerlings of about 3 cm size is believed to be a suitable population density for a one-hectare pond to start with. The increasing need for space as the fingerlings grow reaches its climax about five months after stocking. By that time the growth of fish will be very slow unless the population is reduced to about 3 500 fish. The thinned-out fish, averaging about 140 g each, are sold either as stocking material or as food fish.

With adequate application of fertilizers and with supplementary feeding, within a growing period of 300 days the average yield per ha is as follows:

The heavy demand and the continuing rapid increase in price of some of the marine fishes has generated great interest in their culture. Species that have attracted attention are groupers, Epinephelus altaara, E. awoara and E. brunneus, porgies and seabreams, Mylio berda, M. macrocephelus, M. latus, Siganus rostratus, Chrysophrys major and Evyunis cardinalis. Most of the operations are in experimental stages or on a pilot scale, but some are now commercial ventures.

The fish are cultured in floating cages and in ponds. The cages are made of wire nettings, nylon nettings, wood or bamboo, and are supported by floats or rafts. The Japanese floating net cage fish culture has also been introduced experimentally. Floating cages are easy to make and set up and can be operated on either a small or large scale, and are gaining popularity rapidly. Many of the floating restaurants which normally maintain a few cages as storage for live luxury fish and shrimps are now actually growing and fattening fish in cages.

Ponds are converted from shallow protected coastal areas by the construction of strong embankments and water gates that allow free access to the continuing supply of fresh seawater.

Stocking materials are all collected from their natural habitats. Young fingerlings are reared in floating cages, separately according to species and size. They are given minced trash fish as their main food until they are big enough (7–8 cm) for stocking into ponds. Stocking is done whenever most of the big fish have been harvested or when a supply of large fingerlings is available. The fish in the ponds are fed daily with large quantities of trash fish and other feeds. The cost of production is high, but since the market price is even higher there is profit to the operators.

Traditional types of oyster farming have been practised for over 50 years; modern methods of culture were introduced after 1940, and both kinds of methods are now used. The oysters produced are mainly sold fresh in the local markets, but some are dried and smoked, and the inferior grades are used for making oyster sauce.

Pearl oyster culture operations are mostly under joint ventures with Japanese companies, with Japanese technicians. The scale of operation is small.

Research and training

Research activities on coastal aquaculture are centred on: (1) studies on the problems of water pollution - origin, spread, effects on the life of coastal aquatic organisms and on cultured species, (2) studies on the biology and habits of cultured and some important culturable species, especially the shrimps, (3) improvement of existing culture techniques, and (4) development of new and more efficient techniques. There is considerable interest in the development of shrimp farming, and some studies have already been attempted on the life history, and on experiments on the spawning or rearing of larvae of the important culturable species (Penaeus semisulcatus, P. indicus, Metapenaeus ensis).

Organized training courses on coastal aquaculture have not yet been initiated. However, the Zoology and Botany Departments of the University of Hong Kong and the Chinese University of Hong Kong have courses related to aquaculture.

Problems

1. Gaps in the knowledge of the biology of culturable species.

2. Lack of trained personnel for practical coastal aquaculture.

3. Difficulties of supply of stocking materials from natural habitats; production of fry and fingerlings under controlled conditions have not yet been started.

4. Feeds are expensive.

5. The intensity of water pollution is increasing rapidly and is spreading.

2.3.8 Republic of Vietnam

Area and scope

Vietnam has more than 2 000 km of coastline, plus the huge Mekong River delta. The extensive estuarine areas, mangrove swamps and tidal flats are rich in fisheries production, and about 600 000 ha of these areas are considered as suitable for coastal aquaculture development.

However, because of the availability of a plentiful supply of fisheries products from natural habitats, coastal aquaculture was not attempted until after the second world war. It made a good start, but the development was interrupted by the long years of war and political unrest. At present there are about 20 000 ha of brackish ponds used for finfish and 50 000 for shrimp trapping ponds. The potential for future development is very great for large commercial farming of shrimp, fish, clams, mussels, oysters, etc.

Species suitable for culture

Finfish: Chanos chanos, Mugil sp., Lates calcarifer, Epinephelus spp., Anguilla sp.; crustaceans: Penaeus monodon, P. merguiensis, P. indicus, Metapenaeus ensis, Macrobrachium rosenbergii; molluscs: Anadara granosa, Mytilus sp., Crassostrea spp.

Culture practices

Coastal fish culture is still at a very early stage of development. Milkfish and mullet are the main species. The methods used are “extensive”, resulting in relatively low production - about 10 000 metric tons annually with an average yield of about 500 kg/ha/ann.

Shrimp farming in converted paddy fields is a trapping-holding-growing operation, depending mostly on natural stocking, and without supplemental feeding. The annual production is reported to be about 230 metric tons, an average of 500 kg/ha/ann. The shrimps produced are of mixed species and sizes.

Crabs, oysters, cockles and mussels are collected from their natural habitats, and farming operations have not yet been practised.

Research

Programmes of practical research and experiment on the farming of finfish, shrimps and prawns, oysters, cockles and mussels have already been planned by the Government, and some projects are being started.

Problems

1. Lack of technical personnel of all levels, including skilled labourers.

2. Lack of technical skills and experience.

3. Lack of basic knowledge of the biology of the culturable species.