To promote the protection and sustainability of seahorses for their conservation, efforts have been done through stock enhancement by releasing captive-bred seahorses. However, preparatory activities are necessary for the development of long-term program on seahorse stock release and enhancement by conducting baseline stock assessment, developing the appropriate release and monitoring strategies, and encouraging the involvement of concerned communities in the management of the natural seahorse resources. The Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD), with support from the Government of Japan Trust Fund (GOJTF), initiated seahorse resource enhancement efforts in a remote island community in Negros Occidental in central Philippines. Baseline assessment in 2012 to 2019 of the natural stock of seahorses showed an increasing number of stocks over the years. Results of the transport trials of juvenile seahorses (5-7 cm in stretched height (SH)) suggest an optimum stocking density of 3 ind/L for transport duration up to 12 hours. Appropriate protection of the natural habitat and with no gleaning of various intertidal species, the main source of income for the coastal community, suggests a possible sustainability of the wild seahorse stock. The community involvement may be promoted by active participation thru information, education and communication (IEC) and hands-on trainings during field sampling, seed production and nursery rearing of seahorses. Relevant information derived from the activities in the island community may serve as a model for the resource enhancement of seahorses in other potential sites in the Philippines and other countries in the region.

Diseases continue to devastate the shrimp industry. One culture system that has the potential to abate disease occurrence, improve shrimp survival and environmentfriendly is aquasilviculture. Aquasilviculture is the culture of aquatic organism with mangroves inside the pond (mixed system) or in the receiving environment (separate). A previous study reported that the presence of mangroves in the receiving environment enhances shrimp survival via an improved incoming water quality. The present study determined the time required for a mangrove habitat to remove nutrients from shrimp (Penaeus monodon) farm effluents and the factors affecting mangrove efficiency to remove nutrients. Results showed that ammonia, phosphate, chlorophyll a and total suspended solids (TSS) were fluctuating but statistically lower in water drained into mangrove habitat (Mangrove to Pond Area Ratio, (MPR)=2:1 and MPR=4:1) compared to area without mangroves (MPR=0). At MPR=4:1, ammonia is removed from the water after 3 days; TSS after 2 days; phosphate and chlorophyll a after 7 days. At MPR=2:1, only ammonia can be efficiently removed after 3 days. These results further showed that the type of nutrient and MPR affect the efficiency of mangroves to remove nutrients from shrimp farm effluents. The growth of plants in areas receiving and not receiving shrimp farm effluents were compared by measuring the monthly increase in the seedling height and the increase in the stem length between two nodes in saplings and trees. After 3 months, increase in growth was greater in plants in area receiving shrimp farm effluents compared to those not receiving, except for the seedlings. This indicates that mangroves purify the water by nutrient uptake as supported by the data showing greater increase in stem length in saplings and trees.

Fish and fishery products are always in high demand causing pressure on world fish supply. The world’s wild capture fisheries resources ultimately reached its peak around the early 90s and plateaued at around 90 million tonnes. The stagnancy in wild fisheries production poses an alarm to the ever-growing human population. Fortunately, at around the same time, aquaculture production has filled some gap in seafood supply with over 100 million tonnes produced annually. However, there are various concerns about aquaculture and its sustainability. This is where the idea of aquatic resource enhancement comes in, not only to increase fish yield for food but also to compensate for losses caused by anthropogenic interventions, while promoting environmental rehabilitation and conservation. Resource enhancement, as a whole, can include various concepts on sustainable development, habitat conservation and improvement, ecological management, and aquaculturebased stock enhancement. This paper highlights the development of some resource enhancement programs worldwide and provide some examples particularly those from the Southeast Asian Region. We will attempt to tackle some successes and failures, as well as review past and recent experiences to extract important learnings. Based on these lessons, future directions of how resource enhancement initiatives can be made more efficient and sustainable. As a general rule, we recommend that in order to increase chances of success for programs on resource enhancement, it has to be science-based, there needs to be inclusive and participatory planning and management involving all stakeholders and adheres to responsible culture practices. Moreover, there should be concurrent efforts in reducing fishing pressures, as well as in protecting and rehabilitating natural ecosystems.

This paper describes the present status of aquaculture in Japan. The production volumes of many of the wide variety of aquatic organisms cultured in Japan, including finfishes, bivalves, crustaceans and seaweeds, are on a continuing decreasing trend. According to the national statistical data published by the Ministry of Agriculture, Forestry and Fisheries, the total marine aquaculture production decreased by 20 % by volume in 20 years since 1996 (1.3 million t). In fed aquaculture of marine finfishes, productions of the red seabream (Pagrus major), Japanese flounder (Paralichthys olivaceus) and horse mackerel (Trachurus japonicus) have declined markedly in both volume and value. On the other hand, productions of Pacific bluefin tuna (Thunnus orientalis), which has been included in the statistics since 2012, is increasing remarkably because of the strong affinity of Japanese consumers and the dwindling wild population. Production of white trevally (Pseudocaranx dentex), which is recognized as a luxury foodstuff, is also increasing. Productions of yellowtails (Seriola spp.) and pufferfish (Tetradontidae spp.) are rather stable in terms of volume and value. International demand for yellowtails is growing, and the export is expanding. As for unfed culture of bivalves, productions of oysters (Crassostrea spp.) and Japanese scallop (Mizuhopecten yessoensis) were severely impacted by the Great East Japan Earthquake in 2011, and the production of the oysters, which is on a long-term decreasing trend, has not recovered to the level prior to the earthquake. Production of the major seaweeds (Pyropia yezoensis, P. tenera, Saccharina japonica, S. angustata and Undaria pinntifida) are all on a continuous decreasing trend both by volume and value. Inland (freshwater) aquaculture production is only about 3 % of the marine aquaculture production by volume. About 70 % of the freshwater aquaculture production value comes from Japanese eel (Anguilla japonica), which has been increasing since 2002 due to the increasing unit price despite the decreasing production volume. The insufficient supply of wild glass eel is a problem for the eel aquaculture. The reduced aquaculture production is partially due to socio-economic and environmental reasons. For fed aquaculture, increasing feed cost and international competition are the major issues. Diseases also remain to be a problem. Prevalence of vaccination has reduced the disease damage from about 10 to 4 % of the total production value since around 2000, but the emergence of new diseases continues to occur. Infectious diseases have long been a problem in kuruma prawn (Marsupenaeus japonicus) aquaculture. Red tides still occur almost every year, causing damages mostly in western Japan. For unfed aquaculture, the reduced production is considered to be related with oligotrophication of coastal waters. Intensive reduction of terrestrial nutrient loads by advances in wastewater treatment is thought to have reduced the seaweed productivity, as well as other primary production, resulting in reduced productivity of not only unfed aquaculture of bivalves but coastal fisheries in general. Social factors are also involved. Production declines of many of these species are partially attributed to the reduced labor force due to aging and insufficient recruitment of farmers. The number of management body of oyster aquaculture, for example, decreased from 4,349 in 1963 to 2,018 in 2013. Structure of aquaculture industry in Japan (mostly privately-owned small business) and strong Japanese currency bring about the weak international market competitiveness.

Predictability of food fish derived from the aquaculture sector is a pragmatic concern for the society at large. In this paper, the trend in aquaculture production is presented, with emphasis on the two major food fish species, milkfish and tilapia. Particular interest is on the assessment of observed over-all decline on the rate of output generation in the recent years and its major cause. Accordingly, the impacts on supplies and estimates on the needed catch-up growth rates for the milkfish and tilapia sub-sectors (excluding municipal inland fisheries) are explained. Adjustments currently being implemented by the milkfish and tilapia farming sub-sectors are discussed. Finally, selected prospects related to farming site expansion, emerging farmer-oriented information needs and quality of critical inputs are discussed. In the context of this important occasion, the International Workshop on the Promotion of Sustainable Aquaculture, Aquatic Animal Health and Resource Enhancement in Southeast Asia (SARSEA), interventions offered herein are deemed relevant to the greater Southeast Asian region as well.

Aquaculture has been identified as a priority sector in the development of Malaysia’s economy. It receives a wide participation as a result of the progressive development in most parts of the country. From producing only about 7% of the national fish production in 1992, aquaculture has produced almost 13% to that of capture production in 2003, and expected to produce equal volume to the latter in the future. The aquaculture production leaped from less than 80,000 metric tonnes in 1992 to more than 427,000 metric tons in 2017 valued at MYR3 billion. Demand is expected to continue to grow with anticipated population growth. Aquaculture provides employment, business and investment opportunities in this country. As of 2017, there are over 18,000 aquafarmers in Malaysia, with a total farm size of more than 34,000 ha. Two key factors i.e. the physical and financial factors, have boosted the competitiveness of Malaysia’s aquaculture industry. The National Key Economics Area (NKEA) has become a mechanism to allow big players to lead private sectors participate in this industry. This paper intends to explicate Malaysia’s aquaculture potentials with a view to provide insight prospects for aquaculture growth.

Despite the abundance of potential marine resources, including fisheries, Indonesia is still struggling with several issues, particularly in the aquaculture sector. Environmental issues, aquaculture feeds, fish diseases, and exceeding carrying capacity are some of the many challenges that Indonesia must face these days. The Indonesian government through the Directorate General of Aquaculture (DGA), Ministry of Marine Affairs and Fisheries (MMAF), however, has undertaken efforts to overcome the challenges and at the same time ensuring the sustainability of the sector. Sovereign, competitive, and sustainable aquaculture development policies have been implemented through three main aspects of development: 1) production technology, 2) socioeconomics, and 3) natural resources. Harmonizing and simplifying regulations to encourage investments, interconnecting business chain from downstream to upstream in the industry and strengthening product competitiveness through IndoGAP (Good Aquaculture Practices) implementation are among the steps taken by the government. However, among the efforts to overcome the existing challenges and gaps, Indonesia continues to strive to develop its potential to make Indonesian fish farmers more prosperous and independent in the best possible way.

The technical viability of tilapia (I-ExCEL strain Nile or red) and giant freshwater prawn (GFP) co-culture in cages-within-tanks was evaluated while appropriate feeding protocols for tilapia-GFP co-culture in cages in a eutrophic lake were determined. Specifically, production parameters in all test species grown for five months in tank co-culture (where only tilapias were fed) were compared, while the best feeding protocol from among the following treatments: (a) T_fed—fed tilapias; (b) GFP_fed—fed prawns and (c) T-GFP_fed—both species fed, were defined. I-ExCEL Nile tilapias grew faster in tank co-culture whether reared singly or otherwise. However, red tilapia-GFP tank co-culture gave the best results considering key production traits in all test species (red tilapia —2.52%/day specific growth rate or SGR, 83.3% survival; GFP—1.17%/day SGR, 72.85% survival). Lake-based co-culture was technically feasible at stocking densities of 12.5/m² for tilapia and 2.4 to 4/m² for prawns even when only tilapias were fed; prawns grew to desired marketable sizes by thriving mainly on detritus and natural food organisms in the lake. However, further refinements can still be made to optimise the co-culture schemes to make them more sustainable and provide artisanal fish farmers options in increasing farm yields through multi-species aquaculture.

One of the most recent diseases affecting the shrimp industry is the early mortality syndrome (EMS). EMS, characterized by observed mortality in shrimp within the first 35 days of culture, is due to several diseases, one of which is the acute hepatopancreatic disease (AHPND). Outbreaks due to AHPND have caused economic losses to many shrimp producing countries globally. This paper investigates factors affecting mortality of shrimp, Penaeus monodon experimentally infected with Vibrio parahaemolyticus causing AHPND (VP_AHPND). Tank experiments done suggested that exposure to 10⁷ cfu/ml VP_AHPND, 35°C, and 10 and 28 ppt increase the risk of shrimp mortality due to AHPND. The VP_AHPND concentration in the water that P. monodon can overcome is <105 cfu/ml. Observed mortality due to VP_AHPND is age related, with higher mortalities in younger infected shrimp.