Cambodia has 435 km of coastline with 85,000 ha of mangrove forest. A big part of the mangrove area is in Koh Kong province (63,700) where intensive shrimp culture activity is also concentrated. Shrimp (Penaeus monodon) farms occupy 850 ha, producing 450 tons/yr (1995). But lately, production decreased by 20% due to diseases and self-pollution. The government has since placed restrictions on shrimp farming.

Silvofisheries is a form of integrated mangrove tree culture with brackishwater aquaculture. It is a form of low input sustainable aquaculture. This integrated approach to conservation and utilization of the mangrove resource allows for maintaining a relatively high level of integrity in the mangrove area while capitalizing on the economic benefits of brackishwater aquaculture. Silvofisheries is being promoted in Indonesia as part of a mangrove rehabilitation, conservation and management program. Pond-based silvofisheries follow three design models: (1) the basic “empang parit” model that is essentially identical to an extensive aquaculture pond with maintenance of mangrove trees on the central platform; (2) modification of the basic model to include a dike constructed around the treed central platform so that the water level within the mangrove area and the open water perimeter culture area can be controlled separately; and (3) further modification of the second model to completely separate the open water culture area from the mangrove area by a gated dike with the pond culture area consolidated to a square or rectangular shape at the end of the enclosed diked area. The ratio of mangrove tree to open water culture area is 8:2 to 6:4. In addition, various methods of minimizing the costs associated with pond construction are being considered. This includes the cultivation of mangrove crabs (Scylla sp.) in pens. The State Forestry Company in Indonesia has successfully developed and implemented silvofisheries sites (e.g., 6,000 ha in West Java-Cikiong with 1,508 farmers; 5,300 ha in Blanakan with 2,060 farmers). A conditional lease program with non-government organizations providing technical assistance to farmers has been successful. This program exemplifies what can be accomplished in mangrove rehabilitation and management within a controlled and enforced program. Production and financial return from silvofishery varies with the system, site characteristics, the level of energy input (mainly from mangrove litter - green manure) and utilization by cultured species, among other factors. Annual profit of up to $2,000/ha/yr for a milkfish and shrimp polyculture silvofisheries system has been reported. There is a need to refine data and analysis, since all costs are often not included, and revenue projections are often based on expected production rather than actual production. Farm interviews in West Java showed a range in gross income from $313 to $946/ha/yr while net profit per individual farm (1.5-10 ha farm size) ranged from $943 to $1,558/farm/yr. There was greater production effort per unit area by farmers with smaller farms. Individual silvofishery farmers often combine incomes from multiple sources. The application of silvofisheries practices requires reasonable measures of caution as with any activity in an environmentally sensitive area as the mangroves. Additional important considerations in the development of silvofisheries as part of an activity within the mangrove ecosystem include the issues of land ownership, integrated coastal zone planning and development, comparative economic assessment, systems models, optimizing use of inputs, selection of mangrove tree and aquaculture species, better understanding of trophic production and food web utilization, and improvement of economic return.

Although Japan has large-scale aquaculture, there is no aquaculture development in mangrove areas because the total area is small (553 ha) and strictly protected. Mangroves are preserved in comparatively good condition. Future development of aquaculture in mangrove areas is considered small-scale. Rather than aquaculture, Japan practices enhancement and management of wild fisheries. Tourism is another industry that would have an important role in mangrove utilization. But basic research on mangrove ecosystems is essential prior to determining policies for utilization of mangrove areas. International cooperative research work is important to encourage mangrove-friendly aquaculture and protect the environment.

The paper describes some mangrove-friendly aquaculture activities that are practiced in Malaysia. Among these are the culture of cockle and oyster, semi-intensive culture of tiger prawn, fish cage culture, and pen culture of mud crab. Policies, regulations, future directions and priority areas in research and development that can contribute to sustainable mangrove utilization are discussed.

Culture conditions in tanks were manipulated to improve the growth and agar quality of Gracilaria heteroclada Zhang et Xia. Specific growth rates during culture ranged from -0.51% to 1.40% and gel strength of agar from 439 to 2155 g cm^-2. G. heteroclada at a stocking density of 2kg ton^-1 and fertilized with ammonium chloride at 40 mg L^-1 grew best when water was changed once a month and ammonium chloride was replenished at 20 mg L^-1 after water change. When water was not changed, good growth was observed in plants supplied with 1 mg L^-1 diammonium phosphate on the 3rd wk of culture.

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes a complex comprising three valid species: Leiognathus aureus Abe and Haneda, 1972, widely distributed in the western Pacific Ocean (Taiwan, Philippines, Thailand, Singapore, Indonesia, and northern Australia); L. hataii Abe and Haneda, 1972, currently known only from Ambon, Indonesia; and L. panayensis sp. nov. Kimura and Dunlap, currently known only from Panay Island, the Philippines. The L. aureus complex can be defined by the following combination of characters: mouth protruding forward, not downward; small but sharp conical teeth uniserially on jaws; a black line between lower margin of eye and lower jaw articulation; and lateral line incomplete, ending below posterior part of dorsal fin base or on anterior caudal peduncle. Leiognathus hataii differs from both L. aureus and L. panayensis in having a large dark blotch below the spinous dorsal fin base and fewer counts of scales (lateral line scales 50–58 vs. 64–85 in the latter two species; scales above lateral line 7–10 vs. 12–18; scales below lateral line 22–26 vs. 30–41). Leiognathus panayensis is distinguished from L. aureus in having a deeper body (41–51% SL vs. 35–45% SL in the latter), long posterior limb of maxilla (21–25% HL vs. 15–23% HL), wholly scaled belly (vs. naked along preanal median keel), and a dark blotch on nape (vs. absent).

This manual, describing the pen culture of mudcrab (Scylla spp) in mangroves, is intended for the use of fishfarmers and aquaculturists, extensionists, and students of aquaculture, not only in the Philippines but also in other mudcrab-producing countries in Southeast Asia. It covers the following: Site selection; Installation of net enclosure; Materials; Rearing operation; Feeds and feeding; Stock sampling; Water quality and pen management; Harvesting; and, marketing.

A method of marking abalone (Haliotis asinina Linne) for sea ranching and stock enhancement purposes was developed. Three-month-old abalone juveniles (11.8-mm shell length, 0.28 g) were fed artificial diets for 1, 2, or 3 weeks. The width of the bluish-green shell band produced by abalone juveniles was 1.7, 2.6, and 4.2 mm after 1, 2, or 3 weeks of feeding respectively. The growth and survival of juveniles fed artificial diets did not differ from that of juveniles fed the seaweed Gracilariopsis bailinae (control). Feeding the diet-fed juveniles with the seaweed thereafter produced the natural brownish shell, thus forming a sandwiched bluish-green band. An experimental release in outdoor tanks with natural growth of seaweeds and diatoms, and in a marine reserve showed that the shell band remained clear and distinct, indicating the usefulness of this shell marking method in sea ranching and stock enhancement of abalone.

Mangrove red snapper fed advanced broodstock diets containing squid meal and squid oil exhibited higher hatching rates, cumulative survival and survival activity index than those fed a basal diet or a basal diet supplemented with mixture of antioxidants. On the other hand, fatty acid analyses of ovaries and fry of wild fish and eggs and larvae of broodstock fed raw fish revealed high arachidonic acid (ARA) and docosahexaenoic acid (DHA) levels and relatively lower eicosapentaenoic acid (EPA) levels consequently showing high ARA/EPA and DHA/EPA ratios compared to cold water species. This suggests that ARA may be nutritionally more important for egg and larval development and survival in tropical marine fish and its supplementation in broodstock diets may enhance reproductive performance of mangrove red snapper.