In this study, locally available marine species were tested, milkfish (Chanos chanos) as the fed species, seaweed (Kappaphycus alvarezii) as inorganic-extractive species for the water column, and sandfish (Holothuria scabra) as organic-extractive species on the sediments. This study aims to verify and improve IMTA systems suitable for farm conditions in coastal areas in the Philippines, with emphasis on mitigating the environmental impacts of mariculture of milkfish.

This study aimed to integrate the mangrove clam Anodontia philippiana, which has the capacity to assimilate sulfide in a pond culture system with milkfish Chanos chanos and seaweeds Gracilariopsis heteroclada. Specifically, it aimed to know the effects of integrating other commodities on the growth and survival of milkfish, the primary culture species in IMTA in ponds.

The study was conducted within the integrated finfish broodstock facility complex of SEAFDEC/AQD at Tigbauan, Iloilo, Philippines. The broodstock facility has a water recirculating system. The 500-ton capacity broodstock/spawning tanks were stocked with 25 grouper (Epinephelus coioides) and 90 milkfish (Chanos chanos) breeders. Water from the broodstock tanks passes through the sedimentation tank, then through the filter tank before it goes back to the broodstock tanks. The filter tank has an area of 20 m², a water depth of 25 cm, and a water flow rate of 43 L sec^-1 (≈3720 m³ day^-1).

The nearshore (Soya Warm Water (SWW)) and offshore (Intermediate Cold Water (ICW) and Okhostk Sea Low Salinity Water (OSLSW)) waters in the Okhotsk Sea differ substantially in their physico-chemical characteristics. Thus, the extent to which water mass mixing impacts phytoplankton dynamics in the Japanese scallop Patinopecten yessoensis culture areas needs to be assessed to properly manage scallop stocks. This study examined the phytoplankton dynamics in nearshore (SWW) and offshore (ICW and OSLSW) waters and phytoplankton response to water mass mixing (SWW + ICW, OSLSW + ICW) for 5 days in spring (2007) and summer (2007–2009) microcosm experiments. Increased chlorophyll a concentration in ICW was observed due to higher nutrients available for phytoplankton uptake than in OSLSW and SWW at the start of each microcosm experiment. In comparison to spring microcosm, mixing of SWW + ICW promoted higher chlorophyll a concentration and faster Si(OH)₄ utilization than in OSLSW + ICW in summer. In addition, the size structure of chlorophyll a differed from micro-size (>) in SWW + ICW to nano-size (<) chlorophyll a in OSLSW + ICW. Suspended particulate organic matter (SPOM) \(\mathsf{\delta^{13}C}\) ratios were positively correlated with chlorophyll a in both mixed microcosms whereas SPOM \(\mathsf{\delta^{15}N}\) isotopic ratios were inversely related to nitrate concentration in SWW + ICW, except in spring. This suggests that stable isotopes can be used in predicting phytoplankton biomass and nutrient utilization. In comparison to microcosm experiments, nearshore water column structure suggests vertical water mixing in summer to autumn when phytoplankton biomass and micro-size fraction were at maximum. Taken together, the advance of nutrient-rich ICW to nutrient-poor nearshore areas in the Okhotsk Sea resulted in increased chlorophyll a biomass and dominance of micro-size phytoplankton in summer, potentially enhancing nutrient and food supply to bottom-cultured scallops as suggested by both microcosm experiments and field observations.

What are sex pheromones and how do they function in the courtship and mating of shrimps and other crustaceans? Best known as chemical compounds excreted by animals to initiate reproduction-related responses from their potential mates, pheromones became an important factor in shrimp culture. An earlier study, showed that the domesticated shrimp had a reduced level of pursuit behavior than the wild-caught and suggested that sex pheromones could have played a role in this behavioral difference. Domesticated penaeids are typically reared communally until ready for use as broodstock wherein animals are continually exposed to varying chemical cues. There is a close relationship between chemicals involved in molting and mating of closed thelycum species but information regarding the effect of prolonged exposure of male penaeids to molting and sex pheromones of females on reproduction behavior is not available. In 2021, SEAFDEC/AQD conducted a research to evaluate the possible implications of monosex rearing on gonad maturation and reproduction behavior of Penaeus indicus broodstock. Results demonstrated that the traditional communal rearing of male and female P. indicus broodstock do not have a significant effect on the ovary development and sperm quality of female and male broodstock, respectively. But this common practice of rearing male and female broodstock together significantly reduced reproductive related behavior leading to lower successful matings compared to when broodstock were reared monosex. This novel information could be linked to previous report on reduced successful matings previously reported in black tiger prawn, P. monodon. Therefore, monosex rearing should be considered as an alternate broodstock setup as this will facilitate optimized sexspecific nutritional manipulation and even potentially increase the mating success of domesticated penaeid broodstock.

Fish diseases have seriously threatened and hampered the aquaculture industry. Low stress yet effective mass vaccination strategies for disease control and prevention are needed for sustainable aquaculture. Fishvax, a vaccine using a nanocomposite biomaterial for oral delivery, was developed and applied in this study for vaccination against Aeromonas veronii, a bacteria that can cause major disease outbreaks in fish. The project team, based at the Institute of Biology, College of Science, University of the Philippines Diliman, was headed by Dr. Anacleto Argayosa, in collaboration with Dr. Rolando Pakingking Jr. of SEAFDEC Aquaculture Department. The project was funded by the Department of Science and Technology, Philippine Council for Aquatic and Marine Research and Development, now the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development.

One dilemma facing the farming of the carrageenophyte Kappaphycus is the deteriorating quality of seedstock. Rejuvenating the commercial stocks using spores from reproductive wild parents that are sexually and asexually produced could perhaps restore the traits that are useful for culture. The use of gametophyte and sporophyte (=tetrasporophyte) phases of Kappaphycus alvarezii from spores is explored as a source of seedstock. The growth and physical properties of semi-refined carrageenan extracted from the resulting sporophyte and gametophyte thalli of the same ages were determined. The growth rate of the diploid tetrasporophyte thalli was significantly higher than that of the haploid gametophyte. Gel strength and yield of semi-refined carrageenan from the two life cycle phases were not significantly different, whereas the viscosity was significantly higher in the diploid tissues. Kappaphycus sporophytes were potentially superior to gametophytes as a source of seedstock for mariculture, but problems need to be addressed – including improving the growth rate and reducing the cost of production – before its application could be realized.