A review is made of current information on Penaeus monodon covering various aspects, including taxonomy, morphology, distribution, bionomics and life history. Reproduction, embryonic development, larval stages, spawning, food and feeding, and physiology are described and applications of such information to culture of the species are considered.

The aim of the present study was to use three PCR-based techniques for the analysis of genetic variability among Vibrio parahaemolyticus strains isolated from the Philippines. Seventeen strains of V. parahaemolyticus isolated from shrimps and from the environments where these shrimps are being cultivated were analyzed by RAPD, ERIC and REP-PCR. Antimicrobial susceptibility of these strains to selected compounds was investigated using broth microdilution method. Results of this work and analysis of similarity among strains using Dice coefficient and unweighted average pair group method have demonstrated genetic variability within the V. parahaemolyticus strains. The RAPD, ERIC and REP-PCR were found to be suitable typing methods for V. parahaemolyticus. They have good discriminative ability and can be used as rapid means of comparing these strains for epidemiological investigation. However, the REP-PCR analysis yielded a relatively small number of products suggesting that the REP sequences may not be widely distributed in the V. parahaemolyticus genome. Results of antimicrobial susceptibility revealed that resistance among the strains was rare. In conclusion, RAPD, ERIC and REP-PCR techniques are useful methods for molecular typing of V. parahaemolyticus strains. To our knowledge this is the first study of this kind carried out on V. parahaemolyticus strains isolated from the Philippines.

This is the first report of the isolation and characterization of a fish virus from the Philippines. The virus was isolated using snakehead spleen cells (SHS) from severely lesioned epizootic ulcerative syndrome (EUS)-affected snakehead Ophicephalus striatus from Laguna de Bay, in January 1991. The virus induced cytopathic effects (CPE) in SHS cells yielding a titer of 3.02 x 106 TCID50 ml-1 at 25°C within 2 to 3 d. Other susceptible cell lines included bluegill fry (BF-2), catfish spleen (CFS) and channel catfish ovary (CCO) cells. Replication in chinook salmon embryo cells (CHSE-214) was minimal while Epithelioma papulosum cyprini cells (EPC) and rainbow trout gonad cells (RTG 2) were refractory. Temperatures of 15 to 25°C were optimum for virus replication but the virus did not replicate at 37°C. The virus can be stored at -10 and 8°C for 30 and 10 d, respectively, without significant loss of infectivity. Viral replication was logarithmic with a 2 h lag phase; viral assembly in the host cells occurred in 4 h and release of virus occurred 8 h after viral infection. A 1-log difference in TCID50 titer between the cell-free virus and the total virus was noted. Freezing and thawing the virus caused a half-log drop in titer. Viral exposure to chloroform or heating to 56°C for 30 min inactivated the virus. Exposure to pH 3 medium for 30 min resulted in a more than 100 fold loss of viral infectivity. The 5-iododeoxyuridine (IUdR) did not affect virus replication, indicating a RNA genome. Neutralization tests using the Philippine virus, the ulcerative disease rhabdovirus (UDRV) and the infectious hematopoietic necrosis virus (IHNV) polyvalent antisera showed slight cross-reaction between the Philippine virus antiserum and UDRV but established no serological relationship with SHRV and IHN virus. Transmission electron microscopy (TEM) of SHS cells infected with the virus showed virus particles with typical bullet morphology and an estimated size of 65 x 175 nm. The Philippine virus was therefore a rhabdovirus, but the present study did not establish its role in the epizootiology of EUS.

Hepatopancreatic parvovirus (HPV) was detected in samples of Penaeus monodon postlarvae (PL-13, PL-18, PL-19, PL-26) from 2 hatcheries in 2 provinces (Samar and Iloilo) in the Philippines. The percentage of infection was 20 to 100% in postlarvae obtained from the hatchery in Samar in August 2001. Postlarvae from the hatchery in Iloilo, sampled in October and November 2001, had 70 to 99% HPV infection. Wet mounts of squashed hepatopancreatic tissue stained with malachite green (wet-mount technique) and histopathology revealed the presence of large, usually single, basophilic intranuclear inclusion bodies in the distal tubules, which led to displacement of the nucleoli. Light microscopy showed ovoid to spherical inclusion bodies, 5 to 11 µm in diameter. Transmission electron microscopy revealed that the inclusion bodies were composed of electron-dense granular material and virions. The virions appeared roughly spherical and averaged 18 to 22 nm in diameter. An experiment was undertaken to induce HPV infection by feeding P. monodon postlarvae with virus-infected postlarvae. P. monodon postlarvae (PL-16), initially determined as free from HPV, were found HPV-positive 24 h after being fed with infected material. The percentage of infection ranged from 30% at Day 1 post-infection (p.i.) to 100% at Day 7 p.i. determined by the wet-mount technique and by histopathology. This is the first report of a successful horizontal transmission of HPV in P. monodon postlarvae.

Many people living in the rural areas in the Philippines, as in other developing countries in Southeast Asia, depend on aquatic resources for their food and livelihood. For the past two decades, the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC-AQD) has been working with fishing communities and people’s organizations, business sector, local government units, national government agencies, non-government organizations (NGOs) and academic and other research institutions to promote the efficient conservation, management and sustainable development of the country’s fisheries and aquatic resources so that these may continue to serve the needs of the people today and tomorrow. Using the lessons learned from those two decades of multi-sectoral and inter-disciplinary collaborations, SEAFDEC-AQD launched in late 2006 a project called Institutional Capacity Development for Sustainable Aquaculture (ICDSA) to hasten the transfer to and adoption by coastal villagers of appropriate technologies that would enhance the productivity of aquatic resources and at the same time safeguard the fragile balance of the aquatic ecology. The experience of SEAFDEC in coastal resource management shows that it is important to engage the collaboration of the local government units and other “on-the-ground” institutions, such as NGOs and people’s organizations, to be able to introduce effectively any social and technological interventions to target community-beneficiaries. However, before a fruitful collaboration among these institutions could be attained, there is a need to build their capacities, and those of the beneficiaries, for the vital roles that they play in the implementation of livelihood projects and environmental management programs. As of January 2008, SEAFDEC-AQD is implementing ICDSA projects in four provinces—Antique, Capiz, Guimaras and Northern Samar in central Philippines. In the pipeline are similar projects for a province in southern Philippines and two provinces in the north.

It is a common belief that the zoea of Penaeus monodon are completely filter feeders. Thus, diatoms like chaetoceros and phytoflagellates are maintained at high feeding densities as much as 80 000 cells/ml in hatchery tanks during the zoeal states of the P.monodon. This feeding scheme often results in the reddening of the larvae followed by weakening, loss of appetite and eventual mass mortality. It was found out recently that zoea larvae are not completely filter feeders. It was observed as early as Zoae 1, the mouth parts of the larvae are already functional and can eat food particles as big as Artimeia and Brachionus. Based on this observation, a new feeding scheme was developed. Boiled egg yolk is fed to the larvae at 15-22 particles (as big as Brachionus) per ml from Zoea 2 to Mysis 3 stages. Tetraselmis is given from Zoea 1 to Mysis 3 stages at a low density level of 5 000 cells/ml. Artemia is also fed at 10-15 individuals/ml from Mysis 1 to Postlarvae 5. If Tetraselmis is not available, bread yeast is given from Zoea 1 to 3 at 0.1-03 g/ton as supplementery feed. With this new feeding scheme, the hatchery producers have been greatly simplified considering that the most difficult and tedious part in larval rearing is the maintenance of algal food especially diatoms. This feeding scheme was tested in a private hatchery in Bataan, Aklan province by the SEAFDEC Aquaculture Department from July to October 1981. All 44 runs were successful, yielding survival rates ranging from 22 to 75 percent and an average rate of 52.9 percent. The hatchery system was further simplified when experiments at the Bataan Substation of the SEAFDEC AQD revealed that as high as 60 percent survival can be attained with minimal aeration. Instead of centralized aeration system using compressors or blowers, portable aquarium-type aerators (5-watt) could be use thus minimizing energy consumption. Based on these developments, a new model for a small-scale hatchery system is proposed. based

This study evaluated the feed intake of the milkfish (Chanos chanos Forsskål) in commercial brackishwater ponds under different management regimes. Feed intake and growth were compared between a rather intensive culture management in a fish farm of 1 ha pond size and a semi-intensive one, with a total pond area of 30 ha. The data suggested a direct consumption of only 12 % of the supplemental feed in the intensive farm, leading to a wastage of high quality fish feed and a significantly lower specific and metabolic growth rate (P< 0.001) than in the semi-intensive system without any supplementation and only relying on abundant natural food through fertilization. These results suggest that a heavy reduction in, or even the abandonment of the use of, supplemental feed for milkfish culture would be more cost-effective.

Research on larval rearing of Macrobrachium is reviewed. The future of prawn culture is discussed.

This paper discusses the handling and rearing of hatchery-produced Penaeus post larvae. The survival and growth of hatchery produced fry and wild caught fry are discussed.

Seaweed research at the Aquaculture Department of SEAFDEC focuses mainly on 2 genera of agarophytes (Gracilaria and Gracilariopsis) and carrageenophytes (Eucheuma and Kappaphycus). From 1988 to 1998, research works were mainly on Gracilaria and Gracilariopsis along these areas: (1) refinement of culture technique, (2) basic biology, production ecology, and corp management, (3) product utilization, (4) screening and characterization of natural products, and (5) economics of farming system. Four years ago, the Seaweed Program of the Department re-focused its thrust on Advanced Aquaculture Technologies (Biotechnology) to include also Eucheuma and Kappaphycus in answer to the needs of the industry. This paper briefly describes the highlights of the different studies done on biotechnology.