Shrimp monoculture systems have been beset with devastating losses due to infectious diseases and environmental deterioration. On a global scale, efforts to make shrimp culture a sustainable industry are warranted because of the high value and demand of shrimp. A Code of Practice for Sustainable Shrimp Farming prepared by the Global Aquaculture Alliance has been adopted by various shrimp producing countries addressing issues like mangroves, site evaluation, design and construction, feeds and feed use, shrimp health management, therapeutic agents and other chemicals, general pond operations, effluents and solid wastes, and community and employee relations. Shrimp hatcheries have benefited from technological advances in practically every aspect of rearing including implements to control water quality, eliminate pathogens, and improved nutrition through innovative artificial feeds and supplements. These technologies have made postlarval production very successful, although in many cases, high survival cannot exactly be equated with good quality. Thus a closer look at hatcheries is essential to ensure that rearing protocols match the conditions to which postlarvae will be exposed to upon stocking in ponds. Compiled information on the estimated number of hatcheries and forms in major shrimp growing areas in Asia show a relatively smaller number of small independent hatcheries compared to farms, which demonstrates that effective disease control programmes need to emanate from hatcheries. Presently, three programmes for the hatchery need serious attention. These are (a) the continued implementation of fry analysis procedures, not only as a marketing tool, but so as to exclude pathogenic organisms from ponds, (b) adherence to agreed-upon codes of practice and conformity with accepted guidelines on live transfers to minimise disease spread, and (c) development of a reliable source of domesticated broodstock and incorporating specific pathogen free (SPF) and specific pathogen resistant (SPR) stocks in these programmes to minimise or eliminate dependence on wild broodstock. One of the main constraints is the lack of cost-effective and efficient methods to prevent and correct environmental deterioration, and to maintain biosecurity. In addition to providing primary health care, disease control strategies should be a combination of pathogen exclusion and environmental management: the former for primary pathogens such as viruses and the latter for secondary pathogens like bacteria, whose pathogenicity is heightened by environmental degradation and lowered resistance of shrimps. Shrimp forming should start employing systems to manage and lessen waste and the outflow of organic pollutants that could contribute to self-pollution or deterioration of the quality of receiving waters. These include improved feeds and conversion ratios to make feed utilisation more economical and efficient, implementation of recirculating or zero discharge technology, improving the efficiency of aeration systems, improvement of pond siting, understanding of the pond ecosystem and the role of microbes in the environment. In addition to implementing disease control measures and ensuring product quality in various industry sectors, approaches need to be welded together for a holistic approach to health management.

The SEAFDEC Aquaculture Department studies on mangrove-friendly aquaculture (MFA) can be categorized under two models: a) mangrove filters where mangrove forests are used to absorb effluents from high-density culture ponds, and b) aquasilviculture or the low-density culture of crabs, shrimp and fish integrated with mangroves. In a study using the first model, shrimp pond effluents were retained in an enclosed mangrove area prior to release to receiving waters. Nutrients and other water quality parameters, and bacterial levels were monitored in the untreated effluents and post-mangrove water. In the second MFA model, mangrove pens and ponds installed in old growth and newly regenerating mangrove sites in Aklan, central Philippines were stocked with mud crab Scylla olivacea/S. tranquebarica and shrimp Penaeus monodon. Investment costs, survival and production, and cost-return analysis for the pens and ponds are reported in the paper. Aside from the aquasilviculture trials in collaboration with local government units, other activities in the Aklan mangrove sites are the survey and mapping of the 75-ha area in Ibajay, construction of a treehouse, and the educational use as field site by Coastal Resource Management trainees of SEAFDEC Aquaculture Department and field biology students of the University of the Philippines in the Visayas.

This paper reviews the progress of mollusc and seaweed research at SEAFDEC AQD from 1995 to 1999. Because of the pressing need for seedstocks for stocking, research on the donkey s ear abalone, Haliotis asinina focused on the development of seed production and culture techniques. To improve the spawning performance and egg/larvae production of captive broodstock studies on reproductive biology, management of broodstock and development of diet were conducted. Studies to refine techniques for post-larval settlement and metamorphosis and development nursery rearing techniques were carried out to increase production of abalone juveniles. An artificial diet has been developed to enhance growth rates of juveniles during nursery as well as grow-out. However, since long-term use of artificial feeds did not favor the growth and survival of abalone during grow-out culture in tanks due to difficulties in maintaining water quality, sequential feeding with artificial diets and then seaweed Gracilariopsis bailinae seemed more practical. Broodstock development and seed production were the major research areas for the window-pane oyster Placuna placenta. Gonad development was enhanced by feeding a mixture of high densities of Isochrysis galbana and Tetraselmis tetrahele at a 3:1 ratio. P. placenta larvae reared with Isochrysis as feed showed best growth and survival. Settling stage was reached after 14 days of rearing. A salinity of 34 ppt was optimal for larval survival. Poor growth and survival of larvae was observed at low (10 ppt) and high salinity (40 ppt) levels. Re-stocking immature adults and juveniles was conducted in a depleted coastal bed to evaluate potentials for recruitment of the window-pane oyster. After 91 days, a survival rate of 51% was observed among immature adults. No juveniles survived after re-stocking. Studies on seaweeds focused on three economically important genera of red algae: (1) Gracilaria, (2) Gracilariopsis, and (3) Kappaphycus. These studies are in recognition of Gracilaria and Gracilariopsis as agarophytes and Kappaphycus as carrageenophyte having significant roles in the seaweed industry. Research studies therefore aimed to optimize culture techniques for and to develop environment-friendly aquaculture of these seaweeds. Optimization of biomass production was attempted by manipulating the nutrient environment, biomass density, the proportion of harvested biomass, and crop quality for conversion to agar and carrageenan. The use of G. bailinae as a bio-filter focused on the capacity of the seaweed and its agar to sequester heavy metals like cadmium copper, lead and zinc after exposure to various concentrations of these metals. Likewise, excess levels of nitrogen and phosphorus in a finfish broodstock tank with re-circulating water were reduced, demonstrating the efficiency of the seaweed as a bio-filter in aquaculture. Eco-physiological studies of Gracilaria changii, G. coronopifolia, G. firma, and G. bailinae involved the mass production of spores-in vitro as a possible source of seedlings for outplanting. A socioeconomic survey of Kappaphycus culture in the Philippines revealed that, although expensive, deep-sea farming of K. alvarezii using the multiple raft long-line technique was more productive and profitable than the traditional mono-line or the popularly practiced hanging long-line technique.

Studies on tilapias focused on the refinement of strain comparison methods, refinement and pilot-testing of broodstock improvement procedure, selective breeding and evaluation of red tilapias, genetic variability determination in hatchery-bred tilapia and the development of criteria for tilapia fingerling quality assessment. On carps, feeding of bighead carp (Aristichthys nobilis) to enhance reproductive performance was done and stunting was applied as a technique in broodstock development. Studies on the tolerance of bighead carp fry to low salinities were conducted. Free-living nematodes were tested as alternative larval food. The culture potential of grass carp in lake-based cages was also determined. Research on the native catfish (Clarias macrocephalus) focused on endocrine studies during the final stages of maturation. Hatchery techniques were refined by identification of factors that increase fry production. Practical diets were developed for broodstock, hatchery, nursery and grow-out phases. A collaborative project on the ecological impact of African catfish (C. gariepinus) introduction in natural waters was undertaken. The occurrence of EUS (epizootic ulcerative syndrome) among wild fishes in Laguna Lake decreases the marketability of both wild and cultured fishes from the lake. Hence, the bacteria and virus associated with EUS and their virulence, modes of disease transmission, developmental stages of dermal lesions and hematological changes in severely affected fish were studied. Laguna Lake, where fish catch and aquaculture production contribute significantly to the country s total freshwater fish production, has been the focus of extensive ecological research in collaboration with other local and foreign research and academic institutions.

Research on marine fishes at SEAFDEC/AQD from 1995 to date was mostly on milkfish Chanos chanos. Studies focused on the refinement of broodstock and seed production techniques to improve egg and larval production as well as to eliminate morphological deformities in hatchery-bred fry. A verification study with former shrimp hatchery operators demonstrated the technical and economic viability of the AQD-generated milkfish hatchery technology. Production and efficiency of semi-intensive grow-out in ponds were enhanced by the use of formulated feeds and appropriate feeding scheme. Milkfish farming in the Philippines was critically reviewed and recommendations to sustain milkfish culture production were made. Tobacco dust and metaldehyde formulation were proposed as alternatives to organotin-based pesticides in controlling the population of pond snail. The growth hormone of milkfish has been isolated and purified. Addition of highly unsaturated fatty acid (HUFA)-rich oils in the diet did not improve the quality of spawned eggs of grouper Epinephelus coioides. A protocol for the intensive larval rearing of grouper was developed based on the results of several studies. A semi-intensive seed production method using copepod nauplii during the early feeding stages was also developed as an alternative to intensive method. Metamorphosis of larvae was significantly accelerated by exogenous thyroid hormones. Nutritional studies to reduce the amount of fish meal in grouper diets are in progress. Groupers grown in ponds or cages harbor a variety of parasites. Biochemical criteria to assess the quality of spawned Asian sea bass Lates calcarifer eggs was characterized. Diaphanosoma or other copepods may be an alternative or supplemental live prey to Artemia during sea bass larviculture. A practical diet for sea bass culture was developed. Studies to determine the essential amino acid requirements of sea bass are about to be completed. The effects of immuno-stimulants in sea bass are presented. Induced and natural spawning of mangrove red snapper Lutjanus argentimaculatus in concrete tanks or floating net cages has been documented. An improved larval rearing method has been developed using screened rotifers during the early feeding stage of the larvae. Exogenous thyroid hormones have advanced metamorphosis of larvae. A practical diet for snapper is under development. Research on rabbitfish Siganus guttatus were geared to developing tools for growth enhancement. Pituitary growth hormone (GH) has been cloned, allowing the production of recombinant rabbitfish GH. Rabbitfish prolactin, somatolactin have also been purified. Studies on marine ornamental fish focused on two species of seahorses, Hippocampus kuda and H. barbouri, and on blue tang Paracanthurus hepatus. Progress on the biology, breeding, and seed production of seahorses are presented. Successive natural spawnings of blue tang in concrete circular tank have been recorded.

This chapter reviews information on nutrient requirements, feeds and feeding practices of milkfish.

Mystus nemurus is one of the most commercially important freshwater fish in Malaysia. Even though artificial breeding or reproduction of M. nemurus is done in private hatcheries around Peninsular Malaysia, inadequate seed supply coupled with relatively high fingerling prices limits its production. Presently, the supply of fingerlings cannot satisfy the demand for fish farming due to some constraints on the larval rearing, so larval rearing of M. nemurus has yet to be improved in terms of nutrition requirement and suitable size of food for the larvae. At present, the conventional method of fish larviculture using live food such as Artemia nauplii is being practiced by most Malaysian catfish hatchery operators. Using expensive live food like Artemia has made the mass production of catfish fry/fingerlings less profitable. Alternative measures are necessary in order to help minimize importation and use of Artemia. Indigenous species of live food organisms, which are great potential as feed and can easily be cultured and mass-produced at low cost, may be used as substitutes. Studies on those live foods are lacking, hence this study was conducted to determine the effect of different live foods on growth and survival of Mystus nemurus larvae.

To integrate production of crabs and shrimp with mangrove conservation, the SEAFDEC Aquaculture Department initiated studies on Mangrove-Friendly Aquaculture (MFA). Culture pens and ponds in old growth and newly regenerating mangrove sites in Aklan, central Philippines were stocked with mudcrab Scylla olivacea/S. tranquebarica. Investments costs, survival and production, and cost-return analysis for mudcrab culture in pens and ponds are reported in the paper. Aside from the aquasilviculture trials in collaboration with local government units, other activities in the Aklan mangrove sites are the survey and mapping of the 75-ha area in Ibajay, construction of a treehouse, and the educational use as field site by Coastal Resources Management trainees (of SEAFDEC-AQD) and field biology students (of the University of the Philippines in the Visayas).

Juveniles of Haliotis asinina, 10 mm shell length were subjected to four photoperiodic regimes namely, 6L:18D, OL:24D, diffused 12:12D, and ambient light (12L:12D) serving as control. Juveniles were fed fresh seaweed, Gracilariopsis bailinae, in excess amounts throughout the experiment. At the end of a 105-day experiment, juveniles held under ambient photoperiod were significantly bigger and had higher average daily growth rate than the rest of the treatments. Feed conversion efficiency was higher at ambient light than at other photoperiodic regimes. Daily feeding rates at 65-day culture period were similar for all treatments; however towards the end of culture period, feeding rate of abalone at ambient light was lowest compared to the rest of the treatments. Percent survival was significantly higher in animals at ambient light and at 6L: 18D with 99% and 97% respectively, than at other photoperiodic regimes.