Resource use was investigated at 34 Litopenaeus vannamei and five Penaeus monodon farms in Thailand and 30 L. vannamei and 24 P. monodon farms in Vietnam. Farms varied in water surface areas for production, reservoirs, canals, and settling basins; in pond size and depth; and in water management, stocking density, feeding rate, amendment input, aeration rate, crop duration, and crops per year. Production of L. vannamei averaged 17.3 and 10.9 m.t./ha/yr, and feed conversion ratio averaged 1.49 and 1.33 in Thailand and Vietnam, respectively. On average, production of 1 m.t. of L. vannamei required 0.58 ha land, 5,400 m3 water, 60 GJ energy, and 1218 kg wildfish in Thailand and 1.76 ha land, 15,100 m3 water, 33.7 GJ energy, and 1264 kg wildfish in Vietnam. Resource use per metric ton of shrimp declined with greater production intensity. In Thailand, P. monodon was produced at 0.2–0.4 m.t./ha/yr, with no inputs but water and postlarvae. In Vietnam, P. monodon production averaged 3.60 m.t./ha/yr. Production of 1 m.t. of P. monodon required 0.80 ha land, 36,000 m3 water, 47.8 GJ energy, and 1180 kg wildfish, and resource use per ton production declined with increasing production intensity.
There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm-level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0-1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm-level natural resource use efficiency. Additional research that incorporates economic analysis into on-farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.
Mangrove swamps are key ecosystems along the Vietnam coast. Although mangrove litter is thought to represent an important input of organic matter and nutrients to the coastal aquatic systems, the factors determining the quality and size of this litter flux have not been studied so far. We monitored leaf, stipule, twig, and reproductive litter monthly in monocultures of Rhizophora apiculata mangrove forests of 7, 11, 17 and 24 years old in the Camau province, Mekong Delta, Vietnam. Litter traps were used to measure litter fall production from June 2001 till May 2002. Total litter fall was in the range of 8.86-14.16 t DW ha À1 year À1 . Leaves were the main component, and represented 70% of litter fall production in all stands. Total litter fall was lower in the older stands but the amount of reproductive litter was significantly higher in these stands (17 and 24 years). Biomass of leaf litter was highest between the end of the wet season and the beginning of the dry season. Phosphorus and nitrogen levels in leaf litter were significantly higher in younger than in older stands. Overall, our study indicated that young stands produced the highest input of litter and particularly of nitrogen and phosphorus to the surrounding aquatic system. Consequently, these stands contribute significantly to the fisheries.
Engineering design studies and financial feasibility assessments were made for construction, maintenance, equipment, operations, loan requirement, shrimp sales and predicted cash flows for simulated transformations of extensive shrimp farms to intensive shrimp farms in the Mekong Delta, Vietnam. Farms with less than 2.8 ha of feedbased, aerated production ponds would not be profitable at shrimp yields less than 5 t/ha/year. Profit projections increased in response to greater production area on farms and larger annual pond yields. Farms with 6 ha or more of production ponds and yields of 10 t/ha/year or more had the best profit potential. Greater profitability at higher production intensity resulted from a reduction in the labour cost/product weight ratio as yield per unit area increased. Transformation from extensive to intensive farms would allow greater shrimp production, increase worker income and lessen land and water use. Environmental benefits would include a reduction in sediment starvation of the Mekong Delta, and the option to restore some of the several hundred thousand hectares of mangrove area severely degraded by extensive shrimp farming.These two improvements would be of benefit in retarding erosion along the Mekong Delta coastline. The possibility of intensification and consolidation of the shrimp farming area in the Mekong Delta deserves further consideration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.