Recent advaces in the spontaneous and hormoneinduced breeding of caged sea bass (Lates calcarifer bloch, Family Centropomidae) are reviewed. Spontaneous spawnings follow a semilunar rhythm, with most spawings accurring in the evening of quarter moon. Independent of the Lunar-associatd rhythm, mature sea bass which have attained the critical oocyte size of 0.40 mm spawns after an injecton or implantation of luteinizing hormone-releasing hormone analogue (LHRHa) Pelleted LHRHa along together with methyltestosterone can advance sexual maturation and spawning in April-May, ahead of peak breeding in July-August. Depending on the pelleted or injected LHRHa dose, mature female sea bass spawns singly or consecutively over 4 evenings. LLHRHa-induced egg release peaks during the first day of a multiple spawning bout. Daytime injection of LHRHa stimulates spawning in the evening until dawn, while fish injected LHRHa at night induces spawning at daytime and releases fewer eggs compared to nighttime spawning. these results optimize the use of LHRHa to stimulate gonad maturation and spawning so that sea bass seed are made available for hatchery rearing and grow-out.

Epizootic ulcerative syndrome (EUS) is a disease of wild and cultured freshwater fishes in Asia and IndoPacific (Roberts et al., 1986; Lilley et al., 1992). In the Philippines, the first confirmed EUS outbreak is reported in Laguna de Bay in December 1985 to February 1986 (Llobrera and Gacutan, 1987). Since then, EUS has been observed annually in the lake during the coldest months of the year - December to February or March. The disease has spread throughout Luzon, affecting wild and cultured fishes in lakes, ponds, paddy fields, and rice fish systems (Bondad-Reantaso et al., 1992). In September to December 1990, EUS was recorded among brackishwater and marine fishes from a lagoon in northern Luzon (Reantaso, 1991). Although EUS is recognized as a regional problem, no definite primary causative agent has been established. Virus, fungi, bacteria, and parasites have been isolated in EUS-positive fishes, but none has been implicated as the primary pathogen (Roberts et al., 1993a & 1993b). Among the bacteria associated with EUS, Aeromonas hydrophila is consistently isolated in affected fishes from the Philippines (Llobrera and Gacutan, 1987; Torres et al., 1990; Lio-Po et al., 1992). This paper reviews the work done on the bacterial aspects of EUS in the Philippines.

The feasibility of rearing seabass, Lates calcarifer, fry for fingerling production in illuminated floating nursery cages was determined. In experiment 1, seabass fry of 20.0 mm mean TL were stocked at 600 and 1200 in 1 m³ illuminated cages and reared without supplemental feeding. Control fish were stocked at same densities in non-illuminated cages and fed minced trash fish. After 42 days, fish held in illuminated cages at either density had higher specific growth rates (SGR) and percent survival (20-38%) than those of fish reared in non-illuminated cages. Mean number of zooplankton trapped inside the illuminated cages was significantly higher than those found in the non-illuminated cages which was dominated by Copepods such as the Calanoid, Cyclopoid and Harpacticoid and their nauplii. In experiment 2, minimum body size of seabass fry at stocking in illuminated cages was determined. Seabass fry of 7.35, 11.30, 18.73 and 20.71 mm total length (TL) were stocked at three replicates in illuminated cages and reared for 30 days. Percent survival was significantly higher for fish stocked at an initial size of 11.30 mm TL than the other size groups. Number of “shooters” (range = 6-9%) was significantly higher among fish with initial size of 7.35 mm and 20.71 mm than in other groups. SGR of 8.28%/day was highest for fish with mean stocking size of 7.35 mm TL. Feeding incidence (FI) ranging from 13.16 ± 6.7% to 54.9 ± 4.2% was similar for all size groups during the first week of rearing and significantly increased towards the end of rearing period except for fish stocked at 7.35 mm initial TL. Results showed that nursery rearing seabass fry in illuminated cages is feasible. Natural zooplankton were attracted into the cages by artificial illumination sufficiently served as food to fish. Minimum stocking size of seabass fry is from 10-15 mm TL for better survival. Early transfer of fry in nursery cages and availability of natural zooplankton through artificial illumination can be a cost-effective method of nursing seabass fry.

The chemical composition of Spirulina platensis NIES-46 and K-2 strains grown under varios condition of hight intensity and temperature were determined. The dry weight, chla, carotenoid, carbohydrate, protein, and lipid content in INES-46 strain were affected by various light intensities. Changes in carbohydrate, protein, and pigment content in INES-46 and K-2 strains occurred with different temperature condition, with the growth yield of NIES-46 strain increasing significantly with increased protein content. S. platensis NIES-46 and K2 strains contained sufficient quantities of essential amino acid except for methionine and histidine. The increase in the content of 18:2 and 18:2n6 fatty acids with respect to changes in light intensity and temperature would be important in maximizing their in S. platensis.

The article highlights the SEAFDEC Aquaculture Department's (Philippines) Community-based Fishery Resource Management Project activities. Several problems encountered in project implementation and the suggested ways in dealing these problems are also presented.

During the past two decades, many investigators have assumed that the major locus of regulation of cysteine catabolism is the partitioning of cysteinesulfinate between its decarboxylation and transamination pathways. Hepatic cysteinesulfinate decarboxylase activity correlates well with the capacity of animals to synthesize taurine1–4, and low cysteinesulfinate decarboxylase activity in the cat has been associated with its nutritional requirement for dietary taurine5. More recent studies in our laboratory have indicated that cysteinesulfinate-independent pathways also play a major role in cysteine metabolism6,7. In contrast to cysteinesulfinate-dependent metabolism of cysteine, which leads to both taurine and sulfate production, the cysteinesulfinate-independent pathways all result in release of reduced inorganic sulfur and its subsequent oxidation to sulfate. This evidence revealing a contribution of cysteinesulfinate-independent pathways to cysteine catabolism suggested that partitioning of cysteine between cysteinesulfinate formation and metabolism by cysteinesulfinate-independent pathways may also be important in the regulation of cysteine metabolism to taurine.

Snakehead (Ophicephalus striatus) and catfish (Clarias batraclus) with the Epizootic Ulcerative Syndrome (EUS) were sampled for bacteria. Total bacterial counts of skin and muscle/dermal lesions revealed mean colony forming units (CFU) per gram tissue of 1.22 x 10³, 1.40 x 10⁵, 5.31 x 19⁵ and 1.14 x 10⁷ in apparently normal, slightly lesioned, moderately lesioned and severely lesioned snakehead samples, respectively. In catfish, mean CFU per gram tissue were 4.30 x 10⁴ and 2.00 x 10⁵ in apparently normal and slightly lesioned specimens, respectively. Kidney samples likewise revealed the presence of bacteria. Bacteria isolated on trypticase soy agar and Rimler-Shotts medium were predominantly Aeromonas hydrophila occurring in 90% of snakeheads and in 33% of catfish specimens. Infection experiments of A. hydrophila injected intramuscularly into healthy snakehead and catfish induced dermo-muscular necrotic lesions. A dose of at least 10⁶ cells of A. hydrophila was required to induce EUS-like lesions in snakehead and catfish at 21-25 degree C in 24-96 h.

The Philippines is an archipelago of more than 7,100 islands with 17,460 km of coastline, including mangrove forests which covered about 450,000 ha in the 1920s. Coastal aquaculture began a few centuries ago when earthen ponds for the culture of milkfish (Chanos chanos) were first converted from mangrove swamps. For a long time, coastal aquaculture was synonymous with milkfish pond culture; while prawns and shrimps were incidental byproducts resulting from wild fry that entered the ponds during tidal water exchange. In 1943, studies on low density monoculture of the giant tiger prawn (Penaeus monodon) using wild fry were initiated at the Dagat-dagatan Experimental Station of the Bureau of Fisheries in Malabon, Rizal Province. Information on the ecology and early life history of P. monodon generated by the Institute of Fisheries Research Development of the Mindanao State University (MSU-IFRD) in the early 1970s was used in setting up the first experimental prawn hatchery at IFRD. This was followed by the establishment of big-tank and small-tank hatcheries at the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD) in Iloilo Province. An active technology transfer program that included short-term, hands-on training courses on small-scale hatchery starting in 1977, contributed to a dramatic hatchery production of 15 million prawn PL in 1978. Based on the earlier Dagat-dagatan studies, SEAFDEC/AQD started higher-density (semi-intensive) growout pond experiments with P. monodon in the mid-1970's. At that time, farmers started stocking more than 10,000 PL/ha using hatchery fry. Soon after, the first intensive culture trials, using imported Taiwanese technology and feed formulations were undertaken by a Philippine food conglomerate. The availability of both seed and feed, and the attraction of lucrative export market prices contributed to the take-off of the prawn industry. In 1983, when the country's 56 hatcheries produced 85 million PL's, and commercial pellets for intensive culture first appeared in the market, pond production totalled 12,100 MT, a quantum leap from a harvest of only 1,800 MT the previous year. Since then production of PL, adults and exports have steadily increased to a peak of 20,000 MT of exports from 40,000 MT of pond harvests in 1988. The following year the bubble burst. From a high of P200/kg (US$1 =P21) in 1988, farm gate prices plummeted to as low as P70/kg in mid-1989 due to Southeast Asian excess production of black tiger prawn, and to prawn exports from China glutting the Japanese market. This chapter discusses the various components of the Philippine prawn industry with a focus on growout, problems of the farming sector, and problems of the industry as a whole. Lastly, recommendations are offerred for long-term viability.