A great variety of seaweeds grow abundantly along the 81,000-km coastline of the 13,000 islands comprising the Indonesian archipelago. However, it is only recently that the economic importance of seaweeds has really been appreciated. At present, seaweeds collected in Indonesia are mainly used for food supplement, domestic agar manufacture, and for export. Because of the increasing demands for the carrageenan-containing seaweed, mass cultures have been undertaken in both experimental and production sites established in many parts of the country. These efforts are expected to increase the annual volume of exports from 2000 to 6000 mt. The paper reviews the state and problems of seaweed utilization, development, and farming efforts in Indonesia.

An outline is given of research conducted at the Aquaculture Department of SEAFDEC at Rizal, Philippines regarding algal culture and utilization. Culture methods for both brackishwater and freshwater algae are described and details given of applications of microalgae in the aquaculture industry, which include feed for fish and shrimp larvae.

The bulk of world seaweed production today comes from developed countries in the temperate region, including Japan, China, and Korea. The seaweed production potentials in the developing countries of Asia will have to be explored to meet the increasing world demand. Extensive shallow and farmable reef areas as well as cheap labor highly favor seaweed production. Harvesting from natural stocks is unreliable; efforts should thus be directed toward actual farming of seaweeds. In the Philippines, development of the farming technology on Eucheuma alvarezii and E. denticulatum significantly increased production by the middle of the 70 s. Harvests of Eucheuma from farms and other seaweeds from natural stocks now rank third among the fishery exports of the country. The socioeconomic implications of the development of the seaweed resources in the developing countries of Asia are discussed. The Philippine experience is cited specifically to show the benefits derived from seaweed farming technology.

A brief discussion is presented on the commercial importance of seaweeds in the Philippines, which is mainly concerned with their use as sources of industrial gums such as agar, carrageenan, and alginic acid. Carrageenan as a substitute for microbiological agar and the use of seaweeds as a binder of heavy metal pollutants are examined.

Trentepohlia odorata, a filamentous green alga, grows profusely and imparts an orange color on walls of many high-rise apartment buildings in Singapore. Since bulk cultures are needed in the screening of possible chemicals to control infestation, variations in the growth and development of the alga in the laboratory under different physico-chemical conditions were investigated. Bold's medium either as a liquid or solidified with agar was suitable substrate for the culture of the alga. An acidic growth medium (pH 4.5-6.5) favored the formation of sporangia that developed into yellowish-green colonies, whereas a basic medium (pH 7.5-9.5) produced green colonies and no sporangia. An agar concentration of 0.7% as well as the addition of thiamine to the liquid basal medium enhanced the production of sporangia developing into numerous daughter colonies after two months. High relative humidities increased colony growth and promoted the formation of yellow colonies of cylindrical cells. On walls of buildings, the cells are elliptical to barrel-shaped, bright orange, and possess few sessile sporangia. In cultures where moisture and nutrients are not limiting, cells are narrow and elongated, with the filaments radiating from a central mass, and the sporangia are of the sessile and pedicellate types.

The manual on milkfish (Chanos chanos) broodstock management covers the following topics: reproductive biology; sources of broodstock; holding facilities for broodstock; feeding; determination of gonadal development; spawning and egg collection; transport of spawned eggs; determination of percent viable eggs; and determination of hatching rate.

The manual addresses sea bass (Lates calcarifer) fry production in the hatchery. It describes the principles and practical procedures for rearing sea bass - from eggs until metamorphosis - as practiced by the SEAFDEC Aquaculture Department in Tigbauan, Iloilo, Philippines. It is presented under the following main section headings: General principles; biology; Selecting a suitable site; Design - tank systems, seawater supply system, freshwater supply system, aeration system, other facilities; Broodstock - source of breeders, breeding techniques; Egg collection, transport and hatching; Larval rearing - stocking density, feed types and feeding management, water management size-grading of larvae; Harvest and transport of fry; and, Propagation of larval food - Chorella, Brachionus, Artemia, Moina.

This paper describes the sense organs and some of the behavioral characteristics of milkfish (Chanos chanos ) fry, based on studies conducted at the Aquaculture Department, SEAFDEC, Philippines and at Kagoshima University, Japan in 1982. Based on the experimental results obtained and the observations made in the Philippines, Indonesia, and Taiwan, existing fry collection techniques such as the employment of fish lamps and scare lines are considered effective and rational. Several recommendations are made for improvements of the collection gear and for research on fry behavior.

This paper reviews the work on milkfish (Chanos chanos ) culture techniques conducted from 1973 to 1983 by the Brackishwater Aquaculture Center, the aquaculture research arm of the College of Fisheries, University of the Philippines in the Visayas at Leganes, Iloilo, Philippines. Significant findings and innovative techniques dealing with milkfish fry collection and fingerling production such as those obtained from survival studies of fry during collection, sorting, handling acclimation storage, transport, and rearing in nursery ponds or land-based nurseries are reviewed. Fingerling production utilizing improved methods and techniques is discussed. Results of work on pond culture techniques are presented and discussed.

The present methods of collecting fry and fingerlings involve filtration by mobile or stationary devices. The bottom topography of the fry ground, wind direction, and tidal fluctuations are the most important considerations in the design and construction of fry and fingerling catching gear. The behavior of young milkfish (Chanos chanos ) in the different environments where they are exploited determines the catching methods to be employed. Collection, handling, storage, and transport activities expose the fish to undue stress, which contributes to poor survival. The simple method of lowering the salinity of the water medium considerably reduces mortality. Prior acclimation history has significant effects on subsequent survival and adaptation. Although it appears that milkfish fry are more hardy than the fingerlings, both have the same capability for resisting subsequent environmental stress provided sufficient time is given for the fish to recover from previous stress.