Based on the results of a survey conducted on the urease activity (UA) in commercial shrimp feed containing soybean meal (SBM) (0.00-29. 70 ppm UA), a study was carried out to determine the effects of different heat treatments on the UA, and on the nutritional quality of SBM. The effect of these heat treated SBMs when incorporated into shrimp diet on the growth and survival of Penaeus monodon juveniles was likewise tested. Various levels of UA in SBM were obtained with different heat treatments. Six practical diets were formulated and contained 0.00 (SBM heated at !20°C for 20 min); 0.50 (SBM heated at 60°C for 160 min); 4.0 (SBM heated at 60°C for 80 min); 8.0 (SBM heated at 60°C for 40 min); 11.0 (SBM heated at 60°C for 20 min) and 22.0 ppm UA (without heating). These diets were fed to P. monodon (average weight = 4.24±0.10 g) juveniles for a period of 60 days. Results showed that protein quality in terms of amino acid content of SBM was not significantly affected by the different heat treatments. Weight gains of shrimps fed diets with 8.0, 11.0, 25.0 ppm UA were significantly lower than those fed other diets. Survival of shrimps was lowest with diets containing unheated SBM, but this was not significalltly different from those heated at 60°C. Heat treatment of SBM at 120°C is adequate to be an effective ingredient in shrimp diets.

This chapter focuses on the historical and current practices of milkfish farming in the Philippines. The Philippines ranks among the top 12 largest fish producers in the world and the milkfish, Chanos chanos, is the official national fish. The milkfish production in the Philippines has fluctuated sharply, but on average, has relatively stagnated over the past decade, partly due to the shrimp boom and low price of milkfish. The milkfish industry has been responsible for the significant loss of valuable mangrove swamps and forests. The loss of mangrove means loss of habitats and biodiversity including nursery grounds for feeding and refuge of commercial fishes, shrimps, crabs and mollusks. Milkfish ponds in the Philippines are either privately owned or leased from the government. Brackish water fish ponds are valuable real estate and good management adds to their value. For milkfish farming, stocking rate should be based on the pond environment and carrying capacity, and the fish size at stocking and the market size desired.

Philippine Mangroves have decreased from around 500,000 ha at the turn of the century to 132,000 ha in 1990. Given the varied and important socioeconomic and ecological functions of mangroves including harvest of forestry and fishery products, coastal protection, erosion control and pollution abatement, there is a need to rehabilitate degraded areas. Half of the mangrove areas lost in the las three decades can be traced to the construction of 141'000 ha of brackish water ponds monocropped to mik fish or shrimp. Integrated aquasilviculture is an alternative, although experimental, technology that combines both the fisheries and forestry functions of the mangrove ecosystem.This paper describes four models of mangrove rehabilitation and conservation with varying degrees of community participation in the philippines-monoculture mangrove planting in Kalibo, Aklan; mixed species planting in Silay City, Negros Occidental; aquasilviculture in Puerto Galera, Mindoro Oriental (family) and in Hinobaan, Negros Occidental (association)- and compares their strengths, weaknesses, opportunities and threats.

From merely growing shellfish and macroalgae along the freinges of the sea, man is naw growing marine fish in cages thus expanding the range of mariculture. While the farming of shellfish may have its own set of problems it is the growing of fish that particularly poses more serious problem. This is especially true since high value fish which invariably are carnivores are the preferred species. Depending on the hydrography of the site, the species culture, culture method, stocking density, feedtype, and husbandry practices marine fish farming has the potential of greatly increasing the organic load of the immediate waters. the use of chemicals such as therapeutants, vitamins, pigments, and anti-foulants futher adds to the pollution. If the rate and manner of development is left to market forces its sustainability may be jeopardized. Areas that are semi-enclosed are often preferred and can rapidly become subject to overcrowding to the extent that its carrying capacity is exceeded. In addition conflicts between growersand other users can arise thus adding a social dimension to the problem. Sustainability of mariculture can be better assured if the development is not haphazard. The concept of zoning and planned development which is now the standard appeoach on land can wery well be applied in the sea. The open waters can be zoned as to type of aquaculture allowable. Beyond zoning, growers can be induced to set up their cages in semi-exposed or even exposed areas where th hydrography is more ideal for growing fish by providing an infrastructure for mariculture. Such infrastructure may consist of nothing more than mooring facilities for deep-watercages and, where necessary, floating breakwaters. With proper spacing of the mooring points, even the density of the cages in an area can be regulated. This will effectively lower start-up cost since growerswill be spared the expense of installing mooring. This will make it possible to broaden the participation to those with limited access to capita such as small-sscale fishers. Users can be charged mooring fees much as ships are charged berthing fees. Service in the form of security may also be provided. this can be complimented by onshor facilities such as a landing area, feed depot, ice plant, cold storage and processing plant. Such an area can be operated like a marine version of an aindusrial park and can aptly be referred to as a mariculture park. This model of mariculture development is being tried in the philippines.

Quality of eggs spawned by Epinephelus coioides fed fish by catch (control). Cod liver oil-enriched fish by catch (TFC), and commercial HUFA A-enriched fish by catch (TFS) was monitored. Monthly egg production, spawning frequency, fertilization rate, egg viability, and hatching rates of the control were significantly higher compared to TFS Egg production. Spawning frequency and hatching rate of TC and TFS were not significantly different. Results suggest that varying the species of fish by catch could provide the requirements of E. Coioides broodstock so as to provide quality eggs.

Shrimp harvests from intensive aquaculture have recently declined in areas which have been productive for many years. Because the most convenient, although not necessarily factual, explanation for these crop failures has been the occurrence of infectious diseases, there is a need to consider shrimp health from a holistic point of view. The classical method used for the study of shrimp disease dealt mainly with identification of the causative organism and the search for methods of prevention and control through chemotherapy. The adverse affects resulting from the use of chemicals in aquaculture have led to a clamor for alternative approaches to disease management. For effective shrimp health maintenance and surveillance, the following components need consideration: development of rapid and sensitive methods for pathogen detection; establishment of shrimp tissue cultures for virology; immunological studies, toxicological studies and drug efficacy evaluation. The epidemiological approach to disease management should augment the classic approach to shrimp pathology, and this calls for multidisciplinary cooperation.

Historically, reports on the occurrence of disease problems in milkfish, seabass and grouper were mainly on the isolation and identification of etiological agents. Studies on the tolereance of fish to chemotherapeutants were also conducted. Various species of vibrios and gill-infesting parasites have been associated with diseases in all life stages of these fish. Presently, mortalities due to diseases of unknown etiology, environmental failure and nutritional or husbandry shortfalls affect successful fry production in the hatchery. Morphological deformities in hatchery-produced milkfish fry is a major problem to be solved. In seabass fry production, swim-bladder stress syndrome occasionally occurs and results in mass mortalities. In larval grouper culture, the problem of low survival is being addressed through improved husbandry and nutrition. For cage-held broodstock that naturally spawn in captivity, such as milkfish and grouper, the main problem is fouling of net enclosures in the cages. However, for fish that need hormonal manipulation to spawn, such as seabass and snapper, stressful handling procedures during sampling and hormone injection may lead to injuries and scale loss. The damaged areas become focal points for secondary bacterial infection. Future fish health management strategies in these fish should incorporate a holistic approach to include environmental monitoring, nutritional manipulation, immunostimulants and vaccine use, and biological control in addition to pathogen exclusion in the rearing system and the fish.

META^R metaldehyde formulations were tested under laboratory and faild conditions againts brackishwater pond snails (certhium so.). Under laboratory conditions the LC₅₀ and LC₉₉ 3 days after treatment ranged from 2 - 3.5 and 4.8 - 5.4 kg/ha, respectively. However. these levels proved inffection when applied directly under actual pond conditions. In ponds with snail populatin of about 300/m², a higher application rate of 30 kg/ha is recommended. Application of META metaldehyde concentrations of 0 - 175 kg/ha did not affect milkfish juveniles (1 - 3g body weight) 7 days after treatment. Results suggest that META metaldehyde formulations were effective for pond snail control without detrimental effect on juvenile milkfish.

The Asian catfish, Clarias macrocephalus, is a popular freshwater foodfish in the Philippines. However, grow-out farming of this species is hampered by the lack of juveniles for stocking. A series of experiments on zooplankton feed density, weaning and stocking density were conducted in order to improve production of C. macrocephalus fry in the hatchery.