Vertebrate reproduction is under the neuroendocrine control of the hypothalamic decapeptide GnRH which synchronizes various reproductive events and influences other reproduction related aspects like spawning behavior and pheromonal action in fish. Multiple forms of GnRH peptides have been reported across diverse vertebrate and invertebrate classes. Here we report the partial seabream GnRH (sbGnRH) cDNA sequence cloned from the brain of Channa striatus (snake head murrel) a fresh water perciform with immense economic and medicinal value across Asiatic countries. sbGnRH mRNA was found in brain, gill and ovary of mature murrel with possible implications to the effect of GnRH on pheromonal phenomena and on reinitiation of oocyte meiosis. In keeping with the earlier reported role of GnRH in initiation of oocyte meiosis we here present evidence from RT-PCR, ICC demonstrating an increase in the level of sbGnRH mRNA in ovary from pre-vitellogenic to post-vitellogenic follicles.

The Southeast Asian Fisheries Development Center (SEAFDEC) is a regional treaty organization with 11 member countries. This was established in 1967 to promote fisheries development in Southeast Asia. As one of four SEAFDEC departments, the Aquaculture Department based in Tigbauan, Iloilo, Philippines, has conducted activities for aquaculture research and development in the region. Since 2000, the Regional Fish Disease Project has been implemented at the SEAFDEC Aquaculture Department through the Government of Japan Trust Fund. Under this project, research studies were conducted on various aspects of viral, bacterial and parasitic diseases of fishes and shrimps. In East Asia, koi herpesvirus (KHV) disease initially occurred in Indonesia and Taiwan in 2002. KHV infection was also found in Japan in 2003. This disease had a serious, devastating impact on common carp and koi (Cyprinus carpio) production in Indonesia and common carp production in Japan. Common carp is an important food resource in the rural areas of the region, while koi is internationally traded as ornamental fish among Southeast Asian countries. Under these situations, the Regional Fish Disease Project identified KHV as a serious, transboundary pathogen in the region and decided to work on KHV disease at the SEAFDEC Aquaculture Department in coordination with the SEAFDEC member countries to prevent the spread of KHV in the region. The planned research includes survey of the distribution of KHV in the region, standardization of the PCR (polymerase chain reaction) detection method, characterization of the virus isolated from the region, mode of transmission of KHV, and pathophysiology of KHV-infected fish. To support establishment of the fish disease quarantine and surveillance in Southeast Asia, the Regional Fish Disease Project has, since 2002, annually conducted a hands-on training at the SEAFDEC Aquaculture Department on viral diseases of fishes and shrimps for scientists and technical staff from the SEAFDEC member countries. The trainees are expected to play key roles in the diagnosis, prompt information exchange, and surveillance of fish diseases, including KHV disease, in their respective countries. The Regional Fish Disease Project organized two meetings in March 2004 and will convene another meeting in June 2004: Pre-KHVD Symposium Meeting, International Symposium on Koi Herpesvirus Disease, and Meeting on Current Status of Transboundary Fish Diseases in Southeast Asia: Occurrence, Surveillance, Research and Training.

The read seaweed Kappaphycus alvarezii (Doty) Doty ex. P.C. Silva, commonly called "cottonii" in the processing industry, is used as raw material for the production of the hydrocolloid kappa carrageenan. Through biotechnological advaces, certain carrageenan-producing seaweeds have been truly "domesticated" and are now successfully farmed as marine crops in a number of suitable areas of the world. Significant and sustainable employment opportunities are generated by these activities with few environmental impacts. In mid-2001, the incidence of very heavy epiphytism of cultivated raw material of K. alvarezii (cottonii) was reported for a production centre in the Philippines. This case of epiphytism was "unusual" in that it had been present for a considerable period of time and following epiphyte growth, the seaweed crop began to rot and fall off the cultivation lines (this was not the case of the disease "ice-ice"). The outbreak of the epiphyte infestation followed successional development of an epiphyte community and resulted in a climax population of the read seaweed Polysiphonia sp. This was observed to be preceded by heavy precipitation with consequent siltation reaching the farm site. The presence of the Polysiphonia sp. gave the plants a "hairy" appearance. Where the Polysiphonia was attached, the host plant seemed to produce "galls". The end result was that the Kappaphycus material rotted, fragmented and fell off the cultivation lines. The impact of this epiphyte attack was economically, socially and ecologically serious in that the farmers became disillusioned and either moved from the islands to other cultivation sites, leaving their families behind, or returned to the environmentally damaging practices of dynamite and or cyanide reef fishing. This paper outlines the events of epiphytic settlement and subsequent decomposition of the crop plants. The impact of Kappaphycus farming in the north-east Philippines is outlined as well as steps undertaken to improve the farming practice and enable farmers to return to the sustainable activity of seaweed farming.

Four species of sea lice were found parasitic on ten species of marine fishes either cultured in the coastal ponds or occurring in the sea water supply canals in the Philippines. They are: Caligus epidemicus Hewitt, 1971 on Acanthurus mata Cuvier), Epinephelus coioides (Hamilton), Glossogobius celebius (Valenciennes), Liza parmata (Cantor), Lutjanus argentimaculatus (Forsskael), Monodactylus argenteus (Linnaeus), Oreochromis urolepis hornorum (Trewavas), Oreochromis mossambicus (Peters), Rachycentron canadum (Linnaeus), and Siganus guttatus (Bloch); Caligus quadratus Shiino, 1954 on L. argentimaculatus and S. guttatus; Lepeophtheirus sigani n. sp. on S. guttatus; and Pseudocaligus uniartus n. sp. on S. guttatus and L. argentimaculatus. These ten species of fishes are new host to C. epidemicus, except for O. mossambicu which has been reported to carry C. epidemicus from Taiwan. Caligus quadratus is new to the Philippines and the two species of fish harboring it are the new host. While L. sigani was found only on S. guttatus, P. uniartus was recovered mostly from S. guttatus, and C. quadratus, largely from L. argentimaculatus. Caligus epidemicus exhibits extremely low host specificity and was found on all species of fishes examined.

Recombinant rabbitfish growth hormone (rfGH) protein was expressed in Escherichia coli, BL21(DE3) cells. The cDNA encoding the mature protein of rfGH was first cloned in pGEM-Teasy vector and then transferred to pET-3d expression vector. Expression in E. coli cells was then induced by IPTG (0.4 mM). Inclusion bodies (IB) containing the expressed protein were purified by treating bacterial cells pellet with lysozyme followed by repeated washings in cold water containing Triton X-100, sonication, and centrifugation. IB were then solubilized in 4.5 M urea, refolded at pH 11.3 in the presence of catalytic amounts of cysteine and purified by Q-Sepharose column. Gel filtration on Superdex column showed the purified protein to be a monomeric GH. Based on SDS–PAGE, the purity of the recombinant rfGH preparation is approximately 98%. The recombinant rfGH was tested for its biological activity both in vitro, by its ability to stimulate IGF-I mRNA expression in the liver, and in vivo, by its ability to accelerate growth in rabbitfish fry injected with the hormone. A significant increase in growth was observed in rabbitfish fry given the recombinant hormone. Polyclonal antibody raised against the native rfGH immunoreacted with the recombinant rfGH in Western blots and in ELISA, indicating the suitability of these reagents for future quantification of GH in rabbitfish plasma.

A local algal isolate Tetraselmis tetrathele was studied to determine the suitable levels of three growth factors (nutrient medium, light intensity and photoperiod) for mass culture. Significantly higher population cell count (141.92 × 10⁴) were found in 4-day-old cultures (exponential phase) enriched with Conwy medium and exposed continuously to 93.31–103.5 μmole photon m⁻² s⁻¹ light intensity compared with two other media (F, SEAFDEC/AQD) under the same light conditions. Cultures exposed to higher levels of photosynthetic photon flux density and continuous photoperiod had a significantly higher cell count regardless of nutrient media used. The chemical composition of T. tetrathele varied as the culture aged. Significantly higher crude protein (49.6%) and crude ash (15.9%) were found in cultures harvested at exponential than at stationary phase of growth. In contrast, significantly higher carbohydrate (55.2%) was noted as the culture aged. There was an increase in the percentage of saturated, monoenoic and n-3 highly unsaturated fatty acids at the stationary phase of growth. Addition of filtrate from various phases of growth and from 10-day-old cultures at various concentrations stimulated cell growth of T. tetrathele. This study identified the optimum growth conditions for mass culture of T. tetrathele and demonstrated its change in the chemical composition as the culture aged.

Growth of three strains of Oreochromis niloticus L. fry exposed to salinity stress in the presence of an internal reference fish were compared. The Central Luzon State University (CLSU) strain was obtained from the Freshwater Aquaculture Center, CLSU, Philippines. The ISRAEL strain was acquired from the Philippine government's Bureau of Fisheries and Aquatic Resources National Freshwater Fisheries Technology Center (BFAR-NFFTC), Munoz, Nueva Ecija. The National Inland Fisheries Institute (NIFI) strain was obtained from the NIFI, Bangkok, Thailand. Eight to nine full-sib families (replicates) per strain were split into two groups. One group was grown in freshwater for 2 weeks, acclimated to 32 ppt and reared for 2 weeks and finally grown in freshwater for another 2 weeks. Another group was contemporaneously grown in freshwater polyethylene tanks for 6 weeks. Each replicate family included a size-matched internal reference population of red tilapia strain. Two-way analysis of variance (anova) revealed no significant strain differences (P=0.081; r²=0.106). However, analysis of covariance with the internal reference strain used as a covariate showed significant (P=0.049; r²=0.638) strain effects on specific growth (based on standard length measurements). The ISRAEL strain showed consistently better growth rate in both saline and freshwater environments than the NIFI and CLSU strains. We estimated the statistical power of the two-way anova (ϕ=√(k′−1)(factor MS−s²)/(k′s>²); Zar 1984) to be ∼0.30. There was a 70% probability of a Type II error and no true difference in the growth of the three strains was detected. The use of internal reference strain as a covariate improved the r² from 0.106 to 0.638 and increased the efficiency of the test in detecting a true difference. Other strain comparison studies in our laboratory at the Southeast Asian Fisheries Development Center Aquaculture Department showed that the ISRAEL strain shows better growth than the NIFI and CLSU strains in a crowding stress tolerance experiment, when fed only with rice bran and under restrictive feeding regimes.

The study was conducted to determine if stunting of young bighead carp Aristichtys nobilis (Richardson) would affect subsequent growth and reproduction. Juveniles (3 g each) were stocked directly in cages (control) in a lake or stunted in tanks for 6, 12, 18 or 24 months before being stocked in cages. Initially, body weights and lengths of stunted carp in cages were significantly lower (P<0.05) than those of the control fish. The carp stunted for 6, 12 and 18 months showed growth compensation, although their weights and lengths were slightly lower than those of the control fish. The body weight and length of fish stunted for 24 months were the lowest throughout the rearing period. Sexual maturation occurred only in the control fish and those stunted for 6 and 12 months. However, the onset of gonad maturity was delayed significantly (P<0.05) in males stunted for 12 months and in both groups of stunted female fish. The relative fecundity (44 000–56 000 eggs per kg body weight) and number of 3-day-old larvae produced per female (78 000–89 000) did not differ significantly among the three treatments (P>0.05), but production was somewhat lower in fish stunted for 12 months.

This paper presents the results of an economic analysis of the aquaculture of two species of grouper E. coloides (orange‐spotted grouper, green grouper, red‐spotted grouper) and E. malabaricus (malabar grouper, black‐spotted grouper) for small producers in the Philippines. The findings of the analysis indicate that, based on the assumptions, grouper culture is financially feasible. However, the capital requirements for the broodstock, hatchery/nursery, and integrated system may be beyond the financial means of many small producers. These stages of grouper culture may need to be developed as a larger project by private investors or government. The capital investment requirement for grow‐out (not including purchase of transport boxes) is within the financial means of small producers. Loans or other incentives will need to be made available for the small producer, but the cash flow indicates that these loans can be repaid in the first year of production.

Fatty acid composition was determined in five candidate aquaculture species, mangrove red snapper (Lutjanus argentimaculatus), two rabbitfish (Siganus guttatus and S. canaliculatus), coral trout (Plectropomus leopardus) and striped jack (Caranx fulvoguttatus) sampled in the Central Philippines. Special attention was paid to arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Total lipids of hatchery-produced eggs and newly hatched larvae of mangrove red snapper unexpectedly had equal levels of ARA and EPA. Ovarian polar lipids were subsequently found to have intermediate or high ARA (5.5–10.7%) and DHA (14.4–20.4%) levels but relatively low EPA levels (1.5–1.9%), consequently showing high ARA/EPA (4.4–6.0) and DHA/EPA (7.4–14.9) ratios in wild mangrove red snapper and rabbitfish (S. guttatus and S. canaliculatus). Similar trends were observed even in hatchery-reared mangrove red snapper, rabbitfish (S. guttatus) and coral trout. Not only ovary but also liver and muscle contained relatively higher ARA compared with EPA in mangrove red snapper, regardless of the sample source. ARA, EPA and DHA levels in the polar lipids of wild fry (whole body) ranged respectively from 3.2% to 4.0%, from 2.7% to 4.7% and from 23.5% to 27.6% with intermediate or high ARA/EPA (0.8–1.5) and DHA/EPA (5.9–8.8) ratios in mangrove red snapper, rabbitfish (S. canaliculatus) and striped jack. As overall traits, the five species in the Central Philippines appear to have intermediate or high ARA and DHA levels with low EPA level, consequently having high ARA/EPA and DHA/EPA ratios compared to species in high and temperate northern hemisphere. Thus, the present results indicate that ARA is not a minor component in the tropical species, suggesting that ARA may be nutritionally much more important for egg development and larvae growth in the tropical species than in cold water species. The information of the present study can be used as a guideline for development of appropriate broodstock and/or larval diets in the Philippines.