This collaborative SEAFDEC/ASEAN project aimed to develop sustainable shrimp culture technology packages to address the problems in shrimp culture (e.g. discharges from shrimp farms threatening mangrove and marine ecosystems, clearing of mangrove forests to make way for shrimp ponds, etc.). In this context, a closed recirculating shrimp farming system is discussed touching on: pond preparation, water preparation, stocking, feeding, management, DO level, problems, record keeping, and harvesting.

Misleading identification and subsequent publications on biological, molecular, and aquaculture data of mangrove mud crab (genus Scylla de Hann 1833) is a major concern in many countries. In this study, multiple molecular markers were used for genetic identification of all four known mud crab species under genus Scylla collected from India, Philippines, Myanmar, Malaysia and Indonesia. Internal Transcribed Spacer (ITS-1), Polymerase chain reaction (PCR)–Restriction Fragment Length Polymorphism (PCR–RFLP) and PCR-based species-specific markers were used to resolve taxonomic ambiguity. PCR–RFLP techniques using NlaIV and BsaJI restriction endonucleases were efficient to differentiate four different mud crab species under genus Scylla with specific fragment profile. The results also justified the use of ITS-1 and PCR-based species-specific markers to identify mud crab species available in many countries quite rapidly and effectively. Several new molecular markers generated during the study are reported here to resolve the taxonomic ambiguity of Scylla species and the results reconfirmed that India is only having two commonly available mud crab species which was reported by the authors earlier.

Abalone are among the most important fishery resources with high commercial values worldwide, with Haliotis asinina being the most in demand and widely studied species in the Philippines. Abalone culture in the country mainly depends on the red alga, Gracilariopsis heteroclada, as food for cultured stocks. This however, is not sustainable as this alga is also being farmed both for agar production and human consumption. Hence, other sources of natural food need to be explored for large-scale culture of abalone. This study investigated the viability of Ulva reticulata as food for abalone. This green alga is common in the intertidal zones of the Philippines but of no commercial value. H. asinina early juveniles (N = 60, shell length 2.12–3.07 cm, body weight 1.7–5.9 g) obtained from the Abalone Hatchery of SEAFDEC Aquaculture Department were randomly distributed (n = 10) in three replicate containers and fed with G. heteroclada and U. reticulata for 15 days. After 15 days, abalone fed with G. heteroclada were significantly larger and heavier (2.82 ± 0.04 cm and 4.64 ± 0.19 g) than those fed with U. reticulata (2.62 ± 0.03 cm and 3.45 ± 0.14 g). Abalone fed with U. reticulata also exhibited weakness, hardfoot, and easily detached from the walls of the culture containers. Based on these results, despite its availability in large quantities, U. reticulata could not be solely used as an alternative natural food to G. heteroclada for abalone culture. However, its potential as a partial substitute to G. heteroclada may be further examined.

The effects of dietary poly-β-hydroxybutyrate (PHB) on the lipid and fatty acids (FA) in crustaceans were investigated using Artemia as model species. Supplying PHB either in crystalline or amorphous form significantly increased the whole-body lipid contents of starved Artemia. Co-supplying dietary PHB with bacterial PHB degrader Comamonas testosteroni at 10⁶ cells ml⁻¹ for 24 hr also significantly increased this parameter. These findings have important implications on the lipid-saving effects of PHB in crustacean tissues. Dietary PHB, however, did not contribute to the increase in docosahexaenoic acid (DHA) of the naturally DHA-deprived Artemia. Alternative strategy of co-supplying dietary PHB with highly unsaturated fatty acid (HUFA)-rich emulsion for 24 hr effectively improved the nutritional contents of Artemia and at the same time assured efficient delivery of PHB to the larval predator. According to a ¹³C stable isotope tracer study, the significantly higher δ¹³C levels measured in Artemia 2 hr postfeeding with ¹³C-labelled R. eutropha DSM545 indicate that PHB offered in natural matrix is rapidly assimilated. Overall, this study demonstrated the lipid-saving effects of PHB in Artemia. PHB assimilation following gastrointestinal degradation could attribute to its reported beneficial effects in various aquatic farmed species.

The Philippine seaweed industry is affected by multiple but interrelated risks. Farmers mainly encountered environment-related risks (e.g. disease, pest infestations) which, if unmanaged, could result to production failure. Traders and processors considered volatility of seaweed supply and poor quality of raw materials as precursors of other risks such as increased competition among local traders and processing companies. Gender differences in awareness and knowledge of risks were more prominent among seaweed farmers but not among traders and processors as roles become more homogenous up the value chain. Poor governance resulted in the adoption of informal and market-driven strategies to prevent or minimise losses. However, this restricted farmers to participating in higher-income trading and processing activities and contributed to increased market inefficiency. The lack of government support has also curtailed the capacity of traders and processors to engage in product development and diversification. Gender and community experiences influence and shape people’s understanding of their situations and environment including their coping and adaptive strategies in sustaining livelihoods amidst recurring risk events. Embedding informal structures and the differential needs of the stakeholders in the national institutional framework is therefore essential for the promotion of resilient and sustainable seaweed industry.

Various factors to be taken into account in the operation of a prawn hatchery are examined under the following headings: 1) site selection; 2) hatchery facilities and equipment; 3) larval stages of prawn; 4) spawner and broodstock collection and transport; 5) larval rearing; 6) post-larval rearing; 7) harvesting, packing and transporting; 8) diseases; and 9) economics.

Oyster farming is an important industry both in developed and developing countries. The high demand for oysters has caused overexploitation of natural stocks. This led to dwindling spat fall and unstable production. This study was conducted to compare growth and survival of wild and hatchery-bred spat of the oyster Crassostrea iredalei in grow-out culture. Results of the experiment revealed that both wild (n = 1450) and hatchery-bred spat (n = 1450) had comparable growth rates in grow-out culture. Growth rates of wild and hatchery-bred oysters did not differ significantly at 5.69 ± 0.88 mm shell length (SL) and 8.85 ± 1.07 g body weight (BW) mo⁻¹ and 6.88 ± 1.33 mm SL and 8.26 ± 1.15 g BW mo⁻¹, respectively. Growth rates, in terms of shell length, both for wild (p < 0.05, r = 0.74) and hatchery-bred oysters (p < 0.05, r = 0.76), showed strong positive correlation with salinity. Meat yield was almost the same at 16.41 ± 0.57% for wild oysters and 15.59 ± 0.37% for the hatchery-bred ones. Proximate composition of dried whole flesh oyster samples also showed the same amounts of crude protein, crude fat, crude fiber, nitrogen free extract, and ash in both wild and hatchery-bred oysters. The length-weight relationships of wild [W = 0.000492 L^2.6512 (R² = 86.8%, p < 0.001)] and hatchery-bred [W = 0.000052 L^3.1779 (R² = 92.6%, p < 0.001)] C. iredalei were also calculated from the length and weight data obtained during the duration of culture and revealed higher b for the smaller hatchery-bred oysters. Moreover, mean survival at harvest did not significantly differ at 85.03 ± 1.09% for wild oysters and 85.31 ± 1.40% for the hatchery-bred ones (Two-sample t-test, p > 0.05). The results of this study showed the potential of hatchery-bred oyster spat as seeds for grow-out culture to address the declining number of spat fall in natural oyster beds. Producing the same quality of oysters, it can be inferred that the hatchery-bred spat are just as competent as their wild conspecifics.

The SEAFDEC Aquaculture Department is mandated to: 1) promote and undertake aquaculture research relevant and appropriate for the region; 2) develop human resources for the region; and, 3) disseminate and exchange information on aquaculture. The document provides highlights of activities of the Department for the year 1996.

Bristle patches on the carapace behind the eyes were found for the first time in both males and females of the four species of mud crab Scylla spp. Electrocardiography revealed that the bristle patches of Scylla paramamosain were sensitive to touch (with a glass capillary) but not to chemical stimulation (with sugarcane juice). To elucidate the function of these touch signals, the courtship behaviour of S. paramamosain was video-recorded in a broodstock tank. A male approached a female, extended a walking leg over her carapace, touched her bristle patches with a dactyl, mounted her, and probed the bristle patches further with the third maxillipeds. Touch stimulus may be a signal for courtship in Scylla and one of the chain stimuli for the completion of mating behaviour.