The sea cucumber Holothuria scabra (sandfish) was studied to determine what digestive enzymes are present, to perform a basic characterization of their activity, and to attempt to correlate enzyme activity with nutritional status of the animal. Enzymes alpha amylase, protease (as well as chymotrypsin), cellulase, mannanase, agarase, and xylanase were detected. The enzymes trypsin, alginate lyase and laminarinase were also tested for, but the presence of trypsin was inconclusive, and no alginate lyase or laminarinase was detected. The pH optimum of protease was pH 5 and that of alpha amylase pH 7. Alpha amylase, protease, chymotrypsin, cellulase and mannanase continued to digest their substrates over time. A 2-week starvation experiment showed changes in alpha amylase and protease levels. No differences in cellulase, mannanase, agarose or xylanase activity were detected as a result of the starvation experiment. Another starvation experiment wherein sandfish intestines were sampled every 3 days for 15 days showed that only alpha amylase levels changed with starvation. All samples had lower alpha amylase activity after the withdrawal of feed compared to the day 0 samples. These results suggest the possibility of the use of alpha amylase activity as an indicator of nutritional status, particularly feed deprivation, in sandfish.

It is important to accurately evaluate the wellbeing or nutritional condition of organisms when monitoring the wild stock conditions and improvement in aquaculture techniques; however, reliable nutritional condition indexes have not been established for sea cucumbers. In this study, the effects of starvation on condition factor (body weight / body volume), coelomic fluid constituent (protein, carbohydrate and cholesterol) concentrations and coelomic fluid density were analysed in an attempt to establish a method to determine nutritional condition in juvenile sandfish (Holothuria scabra). Body length, breadth and weight of juveniles produced at the sea cucumber hatchery of the Aquaculture Department, Southeast Asian Fisheries Development Center, were measured after anaesthetisation with 2% menthol-ethanol. Coelomic fluid protein level was analysed by the bicinchoninic acid method. Carbohydrate level was analysed by the phenol – sulfuric acid method. Cholesterol level was analysed by the Zak method. Coelomic fluid volume and coelomic fluid weight were measured. Starvation caused a concomitant decrease in body length, breadth and weight, resulting in no net change in the condition factor. This result indicated that condition factor cannot be used as a nutritional condition index. Coelomic fluid constituent level could be measured with a small volume of sample (i.e. 10–20 μL). Although no clear pattern was observed in coelomic fluid protein and cholesterol levels during the starvation trial, carbohydrate level increased, as did coelomic fluid density. These results suggest that coelomic fluid density and carbohydrate level may be used as indexes for nutritional condition of sandfish without sacrificing the animal.

Apart from a decade of undergraduate teaching, my professional life has been directly or tangentially devoted to mangrove issues. Strife in my native Mindanao pushed my family and me to the peace and quiet of Panay Is. in central Philippines and to research on marine shrimp, the commercial superstars of the mangrove macrobenthos. My early focus was on broodstock development, larval rearing and pond grow-out of penaeids, mainly the mangrove-associated giant tiger prawn Penaeus monodon and the white shrimp P. indicus: Because brackishwater ponds are the dominant aquaculture system in the Philippines, species whose rearing requirements mimic the estuarine habitat, e.g., fluctuating salinity levels, have become the crops of choice. Published papers from this period include a classification of P. monodon egg quality types (Fig. 1: Primavera and Posadas 1981) which allows hatchery technicians to predict larval numbers and the corresponding tank water volume to prepare.

South-East Asia has traditionally been the global centre of production of tropical sea cucumbers for Chinese markets. Early research into culture methods took place outside this region, notably in India, the Pacific region and China. However, recent investment in Holothuria scabra (sandfish) culture has led to some significant advances within this region. The Philippines and Vietnam have been at the forefront of recent efforts, with involvement from substantial national programs and local institutions as well as international donors and scientific organisations. Smaller programs are ongoing in Thailand, Malaysia and Indonesia. Recent advances and simplifications in hatchery techniques are a major step forward, having promoted the development of experimental-scale sea-ranching ventures, and given rise to a small, commercial pond-based culture industry in Vietnam. Technology developments in nursery systems are likely to provide opportunities for culture enterprises in a broader range of environments than is now possible. A major research thrust in the Philippines towards developing cooperative sea-ranching enterprises has demonstrated good potential, and institutional/legislative arrangements to ensure adequate property rights have been tested. Rotational culture with shrimp is proving successful in Vietnam, while the possibility of proximate co-culture of sandfish and shrimp has largely been ruled out. Small-scale experiments in the Philippines raise the possibility of co-culture in ponds with a number of finfish species. Current research directions are looking at diversifying technology to increase success in a range of coastal conditions, better understanding the social and biophysical conditions required for success, and finding ways of effectively scaling-out developed systems and technology.

Koi herpesvirus infection causes significant mortalities in common carp (Cyprinus carpio carpio), koi carp (Cyprinus carpio koi) and ghost carp (common x koi cross, Cyprinus carpio koi). Outbreaks have been reported in many countries worldwide i.e. UK, Germany, Israel, USA, Belgium, South Africa, Switzerland, The Netherlands, France, Denmark, Austria, Italy, Luxemburg and Poland. The first outbreaks attributed to KHV in Asian countries were reported from Hong Kong in 2001; Indonesia in 2002; Taiwan in 2002; Japan in 2003; Thailand in 2005; and Singapore in 2005. Thereafter, research studies embarked on KHV focused on pathogenicity, cell line susceptibility, fish size susceptibility, predilection to fish organs, persistence in fish, vaccine development and application, surveillance and gene sequence analyses of KHV strains. To date, annual active surveillance of the virus in Cambodia, Lao PDR, Myanmar, the Philippines and Vietnam showed that these countries were free of KHV from 2004 to 2007. Several strains of KHV apparently affect koi and common carp in this region indicating that transboundary movement of the virus has occurred not only in Asia but also from Europe and the Americas. The extensive international trade in live ornamental koi fish has largely contributed to the global spread of KHV. Hence, KHV disease (KHVD) was recently added to the list of notifiable diseases of the World Organisation of Animal Health or the Office International des Epizooties (OIE), an indication of the global significance of this viral infection.

Milkfish produced from aquaculture is one of the most traded fish in local markets and it also provides export earnings for the Philippines. Annual per capita consumption of milkfish among Filipinos is 4 kg which comprise the major portion of the 25 kg annual intake of all types of fresh fish. Increasing milkfish production from aquaculture constitutes the strategies for securing fish food supply, especially for the growing middle- and low-income households. However, there are diverging analyses and criticisms on the effectiveness and performance of the milkfish industry in improving access to fish and protein sources among the poor in the Philippines. The generally increasing volumes of milkfish production due to improved technologies are indeed desirable. But higher levels of production does not guaranty the availability and access to fish food supply, especially in geographically dispersed production and consumption centers around the archipelago. Efficiency in marketing perishable fishery products is a crucial factor to ensure availability of safe and fresh milkfish in deficit areas. This review of milkfish marketing literature showed that meeting the milkfish demand-supply gaps, in geographic and temporal sense, is an immediate market objective for the Philippines. The spatial and inter-temporal variations in production volumes influence investment decisions on infrastructures and other public support systems. There is enormous challenge for the industry in view of the declining productivity of capture fisheries, the emerging preference for organic food and value-added forms arising from socio-cultural transformations and lifestyle changes among consumers. This chapter elaborates on the potentials of the milkfish industry by presenting the challenges for traders who should deal with the issues on the demand side of the market; and the challenges for milkfish farmers and processors who should act on the supply side. The constraints and corresponding strategies to meet potentials are also discussed.

Milkfish is the most important farmed fish species in the Philippines. In the last 5 years, milkfish production has been increasing. Culture of milkfish in brackishwater ponds still contributes most to milkfish production, although production from marine cages has been on the rise, recently. To sustain milkfish production, a reliable supply of good quality seeds is imperative. Following the spontaneous spawning of milkfish in floating net cages in 1979, protocols for broodstock management, breeding and seed production were developed and these have been continuously refined over the years. Compared to Indonesia and Taiwan, however, commercialization of milkfish seed production in the Philippines, took a long time to take off. Currently, there are a number of government-run and private milkfish hatcheries in operation. In contrast, milkfish fingerling production in brackishwater ponds has long been practiced in the Philippines and is an industry in itself. Traditionally, milkfish fry were from catch from the wild. Recently, more and more come from local hatcheries as well as fry imported from neighboring countries like Indonesia and Taiwan. Prospects for the milkfish hatchery and nursery industries are discussed in light of the Philippine government initiatives to increase fish production, including milkfish, through mariculture as well as by improving production efficiency in other traditional culture systems.

In this chapter, we provide new data on the timing of ossification of cranial and paired girdle elements, and compare our results, when it is possible, with previous work on early ossification development of Chanos chanos. This is particularly important because of the basal phylogenetic position of Chanos among living ostariophysans and among extant gonorynchiforms as well (see Fig. 3.1). We describe the normal cranial and girdle patterns of ossification in Chanos chanos and evaluate to what extent the cranial development is consistent, or whether some intraspecific differences occur in comparison to previous results by Taki et al. (1987) and Kohno et al. (1996a) based on ontogenetic series grown in the same Aquaculture Department as the specimens used in this study. We assess previously published developmental work in a few ostariophysans and test some previous hypotheses on heretochrony and patterns of diversification. [A study of chondrification versus ossification processes in Chanos chanos is outside the scope of this paper, but it is the subject of a separate paper (Arratia and Grande, in preparation).]

In Southeast Asia, the Viral Nervous Necrosis (VNN) or Viral Encephalopathy and Retinopathy (VER) and the Koi herpesvirus (KHV) infection are currently economically-important diseases of fishes. The VNN affects groupers (Epinephelus akaara, E. coioides, E. tauvina, E. fuscogutatus, E. septemfasciatus, E. malabaricus, E. moara and Cromileptes altivelis), Asian sea bass (Lates calcarifer), mangrove red snapper (Lutjanus argentimaculatus) and milkfish (Chanos chanos) in Thailand, Taiwan, Indonesia, Brunei, Malaysia, Singapore, Philippines and Vietnam. The Piscine nodavirus of the genus Betanodavirus, genotype red-spotted grouper nervous necrosis virus (RGNNV) is predominantly involved. Research on fish species pathogenicity, optimum temperature, cell susceptibility, organ predeliction, pathology, virus reservoirs, experimental infection, vaccination and diagnosis have been reported. The Koi herpesvirus (KHV) infection causes significant mortalities in common carp (Cyprinus carpio carpio), koi carp (Cyprinus carpio koi) and ghost carp (common x koi cross, Cyprinus carpio goi). Outbreaks have been reported among koi in Hongkong in 2001; common carp in Indonesia, in 2002; koi in Taiwan in 2002; and common carp in Japan, in 2003. A dramatic spread of the disease was subsequently observed among most prefectures in Japan, with outbreaks that eventually involved koi carp. In Thailand, KHV was first diagnosed in March 2005 while in Singapore, in Sept 2005. By Feb 2006, two batches of Thai koi exported to Singapore, tested KHV PCR positive from which the virus was successfully isolated on KF-1 cells. In Malaysia, no KHV outbreak was reported but the presence of the virus was detected among koi carp exported to UK in 2000 and in 2001. In 2004, koi carp in Malaysia tested positive for KHV by nested PCR. To date, annual active surveillance of the virus in Cambodia, Lao PDR, Myanmar, Philippines and Vietnam from 2004 to 2008 showed these countries are free of KHV. Recent developments on research of KHV focused on pathogenicity, cell line susceptibility, fish size susceptibility, predilection to fish organs, persistence in fish, vaccine development and application, surveillance and gene sequence analyses of KHV strains. The extensive international trading of live ornamental koi fish has largely contributed to the global spread of KHV. Hence, KHV was recently added to the list of notifiable diseases to the World Organisation of Animal Health or the Office International des Epizooties (OIE).