Fifteen years after SEAFDEC Aquaculture Department first offered its training course on Barangay Prawn Hatchery Management, the giant tiger shrimp industry has grown tremendously. Among the private investors in shrimp (Penaeus monodon) hatchery is Jamandre Industries, Inc. But problems (e.g., scarcity of spawners and lack of effective artificial feeds) led the company to explore culture of penaeid shrimps other than tiger shrimp. Although survival of P. stylilostris and P. vannamei were found to be higher than P. monodon in grow-out ponds and in the hatchery, their culture did not take off in the country. For the penaeid shrimps, technology remains largely an art.

The major commercial shrimp species in the Philippines belong to the genus Penaeus and Metapenaeus. The important penaeid shrimps are: P. monodon (giant tiger shrimp or sugpo); P. japonicus and P. semisulcatus (tiger shrimp and bulik or sugpo); and P. merguiensis and P. indicus (white shrimp and Indian white shrimp or putian). The giant tiger shrimp is the major species cultured in ponds while the others are incidental crops. There are 210,000 ha of potential and existing brackishwater ponds in the Philippines (Fig. 1). Because most of these are underdeveloped, present technologies are aimed at improving production or encouraging the development of new areas. Brackishwater fishfarming in the country is primarily centered on milkfish (Chanos chanos) (Table 1). Shrimp used to be merely an incidental crop when postlarvae from the wild enter the milkfish ponds. In the last decade, many traditional milkfish growers recognize the market of shrimps, primarily the giant tiger shrimp. Polyculture of milkfish and shrimp was practiced, and the fishfarmers shifted to shrimp monoculture when price of shrimp in the international market went up. In the mid-70s, SEAFDEC/AQD developed and extended its shrimp hatchery technology, and hatcheries proliferated throughout the country. Seed supply became abundant, encouraging more people to invest in grow-out culture. However, production remained low and inconsistent since the growout technology remains largely an art. When Taiwanese grow-out technology was introduced in the country and research in shrimp was intensified in the Department of Agriculture, University of the Philippines, and SEAFDEC/AQD, new coastal areas were developed particularly in Negros Island where vast tracts of sugarland and rice land were converted to shrimp ponds. Milkfish ponds were also renovated for shrimp culture. There are four shrimp culture levels in the country, namely: traditional, extensive, semi-intensive, and intensive which vary mainly in pond design, stocking density, feeds and feeding, and water management (Table 2). Only the semi-intensive and intensive culture systems are discussed.

Aquaculture especially brackishwater fish culture in Malaysia has a very high potential for development. It is also a very important source of protein. The three major species cultured in cages are sea bass, grouper, and snapper. They are very popular, especially sea bass which is a highly esteemed delicacy. Sea bass culture started in the mid-1970. The fry was obtained from the wild or imported from Thailand or Singapore. This industry developed slowly because of inadequate supply of seed. During this period also, the culturist had very little experience in managing the cages. As an answer to the problems of the industry, the Fisheries Research Institute (FRI) of the Department of Fisheries, Ministry of Agriculture, Glugor, Penang, established a unit responsible for research on hatchery propagation, larval feed development, and cage culture of sea bass. The Brackishwater Unit of FRI situated in Gelang Patah, Johor is responsible for research and development of sea bass grow-out in coastal ponds. The Marine Finfish Production and Research Centre (MFPRC) situated in Tanjung Demong, Terengganu was set up in 1982 for marine fish fry mass production. The Extension Branch of the Department of Fisheries in Kuala Lumpur is responsible for all extension services, including promotion of sea bass aquaculture as well as other species. The Extension Branch also operates the MFPRC and organizes training on coastal aquaculture at the Brackishwater Aquaculture Centre in Johor. The Fisheries Development Authority of Malaysia (LKIM), a government statutory body formed in 1971 with the objectives of upgrading the socioeconomic status of fishermen and developing the fisheries industry, is also involved in marine fish culture, especially in setting up commercial culture projects involving local fishermen. In addition to government bodies, some universities in Malaysia also carry out activities related to marine fish culture, especially disease studies.

Research studies conducted from 1988 to 1991 focused on breeding, seed production, and farming of thirteen aquaculture species of regional importance. Studies aimed at developing economical feeds, as well as disease prevention and control were undertaken. Guided by the recommendations of ADSEA I (Seminar-Workshop on Aquaculture Development in Southeast Asia; 8-12 Sept. 1987; Iloilo City, Philippines), workshops to review the previous years' progress and identify specific studies for implementation were held annually since 1989 with the participation of academic institutions, government and private sectors. Some 212 studies were implemented. Majority were on tiger shrimp, milkfish, and sea bass. Studies on other species of fishes, crustaceans, molluscs, and seaweeds, as well as larval food organisms, seafarming and economics of hatchery and grow-out culture systems were also undertaken. As of December 1991, 168 studies were completed. Research results were published in 204 scientific journals, proceedings, and other publications. In addition, 27 papers were in press and 63 manuscripts had been submitted. That research output is gaining recognition in the international scientific community can be gleaned from the number of papers published in refereed journals covered by Current Contents (CC). Of the 142 papers published in scientific journals in 1988-1991, 115 (81%) appeared in CCcovered journals. This has increased from 58.8% (124 of 211) in 1976-1987. The active participation of the research staff in scientific meetings is equally evident from the number of publications in proceedings of scientific meetings from 1988-1991 (63).

Aquaculture is still at an early stage of development in Malaysia; however, it has expanded quite rapidly over the past decade or so. Under the National Agriculture Policy, aquaculture development has been given high priority and entrepreneurs are given various incentives and support services. The technologies of various aquaculture systems in Malaysia are already well developed. Many farms adopt intensive culture system and where inadequate fish seed is a constraint, importation from neighboring countries supports culture. It is in the intensive culture system, both in the hatchery and grow-out phases, that diseases often occur. Diseases have resulted in significant economic loss to fish and shrimp farmers. The study of fish parasites has been carried out for sometime but it dealt mainly with taxonomy. The systematic study of fish disease and its documentation are comparatively new. At present, three institutions are involved in fish disease research: Fisheries Research Institute under the Department of Fisheries, Agriculture University of Malaysia, and Science University of Malaysia.

Aquaculture prior to World War II was limited because marine and freshwater fish catches were still abundant. But shortage of fuel and other necessities led to an increase in food prices including fish. The demand for increased fish production in turn increased the number of people involved in fish farming and the number of species cultured to more than 25. The 13 species most commonly cultured include the walking catfish (Clarias batrachus), snakehead (Channa straitus),striped catfish (Pangasius sutchi), gouramy (Trichogaster pectoralis), sand goby (Oxyeleotris marmoratus), grass carp (Ctenopharyngodon idellus), silver carp (Hypopthalmichthys molitrix), bighead carp (Aristichthys nobilis), Nile tilapia (Oreochromis niloticus), freshwater prawn (Macrobrachium rosenbergii), sea bass (Lates calcarifer), grouper (Epinephelus tauvina), and tiger shrimp (Penaeus monodon). Thailand is a major producer of agricultural products in Asia. Large quantities of raw feed materials are produced and consumed each year. Although aquaculture has been in existence as long as land-based agriculture, it has not kept up in terms of feed development. The feeding methods of most cultured fishes are still largely traditional and based on experience using trash fish, rice bran, and broken rice. It was only recently that aquaculture began using feeds to increase production. In 1986, shrimp culture began evolving toward the semi-intensive and intensive systems, and the demand for compound feeds greatly increased. Commercial feed factories expanded to include shrimp feeds, further developing the feed industry.

This paper outlines the opening introductory presentation made at the “Expert Meeting on the Use of Chemicals in Aquaculture in Asia,” which was held 20-22 May 1996 at the SEAFDEC facilities in Tigbauan, Iloilo, the Philippines. Its purpose is to provide a balanced and realistic perspective on the needs, issues and challenges with respect to the use of chemicals in Asian aquaculture. We hope to assist participants in identifying development opportunities and in differentiating real hazards from hypothetical threats to cultured organisms, end-users and the environment as a consequence of chemical use. We do not attempt to provide answers to issues related to chemicals in Asian aquaculture, but rather offer some basic directives and opportunities to the workshop participants to assist them in their discussions and in the compilation of realistic recommendations.

Many aquaculture chemicals are, by their very nature, biocidal, and may be released to the surrounding environment at toxic concentrations either through misuse, or in some cases, even by following generally accepted procedures for use. Thus, there is a potential for mortality of nontarget organisms. Illustrations are provided of three classes of aquaculture chemicals and their effects on non-target biota: 1) use of a carbaryl pesticide and mortality of non-target invertebrates; 2) use of an organophosphate parasiticide and suspected effects on nearby biota; and 3) effects of antibacterial residues in aquatic sediments on the associated microbial community. Efforts to assess the risks posed by aquaculture chemicals are often frustrated by a lack of information on environmental fate and effects, and data needs to resolve this situation are identified.

Various chemicals and additives used in fish and shrimp feeds may have impacts on animal health, product quality and the environment. This paper reviews the use and effects of vitamins (vitamins C and E), essential fatty acids, carotenoids, immunostimulants, hormones and attractants added to feeds for cultured fish and shellfish.

This preliminary review looks into legislation governing the use of chemicals in aquaculture in Asia. Brief assessments are made of the legislation relating to chemical contamination and the use of veterinary drugs and feed additives, a section is dedicated to trade in aquaculture products, and a few conclusions are then drawn. While mandatory measures of control are desirable and feasible, soft law instruments, such as codes of practice and conduct, allow an element of flexibility to be maintained while avoiding undue legislative restraints on scientific and technical progress.