This paper reviews the results of studies on the pond culture of milkfish Chanos chanos Forsskal at the SEAFDEC Leganes Brackishwater Station, Leganes, Iloilo since its establishment in 1973. Substantial contribution on the nursery system includes increased stocking density and survival through the use of nylon substrates, supplemental feeding with rice bran, the use of hatchery-reared and stunted fingerlings as alternative sources of stocks, and improvements in the acclimation process. Studies on monoculture and polyculture in grow-out ponds investigated the use of stunted fingerlings, kitchen or algal nursery ponds, stock manipulation techniques, increased stocking density using the plankton method, method frequency and quantity of fertilization, modular pond culture system, and initial findings on fish diseases. Constraints setting back increased production in the Philippines are discussed.

Malaysia is a fish-consuming country with fish representing 60% of a total animal protein intake. At an annual per capita consumption of 32 kg some 560 000 mt of fish is required for the projected of 17.5 million people in year 2000. Coastal marine capture fisheries, the mainstay of Malaysia's fishsupply, has not shown any increase in landings over the last few years. In fact in 1985 there was a decline of 3.7% compared to 1984 fish landings. This declining contribution of marine fisheries is compensated by an increase in aquaculture production. In 1985, aquaculture contributed 51 709 mt to the total fish supply. This represents 10% of the total fish landings of 514 570 mt or 13% of total table (edible) fish landings. Malaysia does not have a long standing aquaculture tradition unlike its neighbours in the Indo-Pacific. Even then, the industry has seen rapid growth in the last few years. Today there are 19 species of finfishes, crustaceans and shellfish cultured in the country. The main freshwater fish species bred and cultured are bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), Indonesian carp (Punctius gonionotus), catfish (Clarias macrocephalus and Pangasius spp), snakefish gourami (Trichogaster pectoralis) and tilapia (mainly Oreochromis niloticus). Marine finfishes bred and cultured are sea bass (Lates calcarifer), grouper (Epinephelus sp.) and snapper (Lutjanus johni). Penaeus monodon is the dominant marine prawn species bred and cultured but culture of P. merguiensis is receiving considerable interest. Macrobrachium rosenbergii is the only freshwater prawn cultured commercially. Molluscs cultured are the blood clam (Anadara granosa) and the green mussel (Perna viridis). In 1985, blood clam and mussel culture accounted for 87% of all aquaculture production of Malaysia, freshwater fish 12%, floating cage culture of marine fish 0.7% and brackishwater pond culture 0.3%. In terms of value blood clam and mussels represented 30% (M$15M) of total value (M$49.5M), freshwater fish 57% (M$28M),cage culture of marine fin fishes 7% (M$3.4M),and brackishwater pond production 6% (M$2.1M). Aquaculture in Malaysia has considerable growth potential. It is projected that 22 000 ha of mangrove will be opened by the year 2000 for shrimp culture. Some 330 000 m2 of protected coastal waters have been identified for cage culture. Some 6500 rafts can considerably expand the present capacity. In freshwater culture about 8000 ha of land and 17 500 ha of mining pools can be developed while 200 000 ha of artificial lakes and impoundments for freshwater fish cage culture are available. Yet such development is not without constraints. Freshwater finfish culture is hampered by lack of good quality broodstock. There is also a limited market for freshwater finfishes. Marine finfish culture is limited by lack of fingerlings and good quality compounded diet to replace trash fish which is deteriorating in quality and quantity. Marine prawn culture is heavily dependent on wild spawners, the supply unpredictable and inadequate. Acid sulfate soil continues to cause the deterioration of brackishwater ponds. Cockles and mussels can be sold to export markets only if they meet specific quality standards.

This paper reviews the works on mussel and oyster culture conducted from 1975 to 1985 by the Southeast Asian Fisheries Development Center Aquaculture Department at Tigbauan, Iloilo, Philippines. Innovative techniques developed in increasing collection of natural seeds and in improving farming techniques are presented. Results of the work on artificial seed production, bacterial depuration, uptake and elimination of heavy metals by green mussel, investigations on red tides, and microbiology of spoilage are discussed.

Countries in Southeast Asia still display a vivid spectrum of developmental stages in aquaculture, the most and the least developed seen in contiguous areas despite geographic similarities. The Network of Aquaculture Centres in Asia-Pacific is actively involved in the development of aquaculture in the region, approaching it from a holistic viewpoint by integrating issues in environment, resource management, and socioeconomics into its program of work. Constraints related to site, inputs, and markets have assumed more importance in many countries, but transfer of technology is still the problem in about half the region. More intense culture systems, especially shrimp pond and fish cages, have resulted in serious problems of self-pollution, which affects the industry's own sustainability. A recent FAO-NACA regional study indicated that non-aquaculture sectors such as industries, agriculture, urbanization, and tourism have serious impacts on aquaculture, but there is little evidence that aquaculture is seriously affecting non-aquaculture sectors. Sustainability of aquaculture has to be considered along with economic and environmental sustainability. It appears from examples in the region that aquaculture that seriously damages the environment is economically unsustainable. Various constraints that impinge on the sustainability of aquaculture in the region are discussed.

Indonesia has a long tradition in aquaculture, particularly in fresh water and brackish water. Most aquaculture is still in extensive systems with low productivity. Mariculture only started in the 1980s and contributes yet little to the total national production. Aquaculture has become increasingly important, particularly in supporting rural economies. The development of shrimp and prawn culture became a Government priority after trawl fishing was banned in 1980-81. With its strategic geographic position and enormous inland and coastal resources, Indonesia has good prospects in aquaculture.

Health management strategies are very important in aquaculture. In Asia, health management practices are broadly similar for the various aquatic species that are cultured. These focus mainly on maintaining the good health of the organisms throughout the life cycle. Good health management is based on an understanding of the interactions between the environment (water), the host, and the pathogens. In an ideal system, the three factors are balanced to offset a disease process. This balance is difficult to maintain in an intensive culture system and significant mortalities usually result. The outbreak of disease is thus related to poor health management. This paper deals with the health management practices applicable to the hatchery and grow-out stages of shrimp and fishes cultured in the tropics.

Research on seaweeds focused on the carrageenan-producing Kappaphycus alvarezii and the agar-producing Gracilaria spp. Growth of K. alvarezii was better on horizontal lines than on vertical or cluster lines from bamboo rafts. All morphotypes (brown green, and red) grew faster at 50 cm than at 100 cm below the water surface, but the green morphotype showed better carrageenan properties. A socioeconomic survey of K. alvarezii farming in Panagatan Cays, Antique revealed that a farmer has an average annual production of 3 tons/ha (dry) with the fixed bottom and hanging longline methods. Three species of Gracilaria in natural beds in lloilo showed monthly variations in biomass and agar quality; G. heteroclada had the highest biomass and gel strength. When this species was grown in tanks, growth and agar sulfate content were influenced by the interaction of light, salinity, and nutrients. Enriched and unenriched stocks of G. heteroclada differed in agar quality. When G. heteroclada was grown with the tiger shrimp Penaeus monodon in extensive ponds, the highest growth rate and production were obtained at the seaweed stocking density of 250 g/m2; this was in November when average water temperature, transparency, and salinity were low. Salinity tolerance varies among Gracilaria species.Oyster (Crassostrea iredalei) and mussel (Perna viridis) farming in Western Visayas were assessed in 1992 in terms of the culture methods, socioeconomics, marketing, and profitability. A more localized survey of oyster and mussel fanning was conducted through rapid rural appraisal in two coastal towns in 1993. A farmer-participatory study followed in 1994 for the culture of oysters, mussels, seaweeds, and rabbitfishes in a river mouth in Dumangas, lloilo. Green mussel, brown mussel (Modiolus metcalfei), and seaweeds transplanted to Dumangas from Capiz have reproduced. In another study, the green mussel was tested as a biological filter in tiger shrimp ponds; shrimps stocked with mussels grew better than those without. A nationwide survey on the Placuna placenta fishery in 1993 showed 27 remaining 'kapis' beds; many others have been depleted due to excessive gathering, pollution, siltation, and trawling. Broodstocks are being developed to produce 'kapis' seed for grow-out and restocking. For the first time at AQD, adult donkey-ear abalone Haliotis asinina from the wild spawned naturally in laboratory tanks. Juvenile abalones can be successfully grown on Gracilaria or abalone diet.

This paper reviews the interactions between shrimp culture and the natural environment. It considers and gives details of the effects of shrimp culture on the environment and the effects of environmental change on shrimp culture. Examples are given where the environmental impacts on and of shrimp culture have caused serious economic losses to shrimp farmers. The paper concludes that economic sustainability is and will continue to be closely related to how the shrimp farming industry deals with environmental problems. Strategies are considered for improved environmental management of shrimp aquaculture, and priorities are highlighted for future research on the relations between shrimp culture and the environment.

The Community Fishery Resources Management Project, launched in 1991 in Malalison Island, Philippines is a development-oriented research project integrating biology, economics, sociology, engineering, and public administration. The general objective is to support, and learn from, the collaboration of people's organization, biologists, and social scientists in applying community-based techniques in fishery management. During Phase I, the Project concentrated on community organizing, institution building, and the introduction of seaweed farming as alternative livelihood. Studies were made on the marine resources of the island, the traditional boundaries and territorial use rights, the economic utilization of resources in the island, and the cultivation techniques for seaweeds. Phase II started in 1994 with the implementation of the territorial use rights in fisheries and the test deployment of prototype concrete artificial reefs. Phase II includes impact assessment (environmental, social, and economic), institutional arrangements in fishery co-management, ethnographic studies, economics of Seafarming techniques, and management of fishery cooperatives.

Crustacean research at the SEAFDEC Aquaculture Department during the last three years focused mostly on the tiger shrimp Penaeus monodon. Studies were done along six problem areas: (1) developing spawning techniques for captive broodstock, (2) defining physico-chemical levels tolerable by larvae or postlarvae, (3) finding alternative feeds or fertilizers for extensive culture, (4) reducing the cost and evaluating the quality of formulated feeds for semiintensive culture, (5) preventing and controlling disease, and (6) documenting the chemicals used in shrimp culture and their effects on the environment. To reduce feed costs, substitutes for expensive feed components were screened and the specific nutrient requirements of tiger shrimp during culture were determined. A few studies were made on other crustaceans. The vitellogenin levels during maturation of the white shrimp P. indicus were measured. The digestibility of feedstuffs was also tested in the white shrimp. Culture techniques are being developed for the mudcrab Scylla serrata in ponds, pens, and cages.