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In Vietnam, culturing striped catfish makes an important contribution to the Mekong Delta's economy. Water level rise during rainy season and salt intrusion during dry season affect the water exchange and quality for this culture. Sea level rise as a consequence of climate change will worsen these influences. In this study, water level rise and salt water intrusion for three sea level rise (SLR) scenarios (i.e., +30, +50, and +75 cm) were simulated. The results showed that at SLR +50, the 3-m-flood level would spread downstream and threaten farms located in AnGiang, DongThap and CanTho provinces. Rising salinity levels for SLR +75 would reduce the window appropriate for the culture in SocTrang and BenTre provinces, and in TienGiang's coastal districts. Next to increasing dikes to reduce the impacts, the most tenable and least disruptive option to the farming community would be to shift to a salinity tolerant strain of catfish.

Shrimp aquaculture is the biggest source of export income in Vietnam. However, the development of the shrimp poses a serious threat to coastal mangroves by converting coastal mangroves into shrimp farms. Much effort has been made to replant mangroves and reduce the impacts of shrimp farming on the environment, and maintaining mangrove coverage at 30–50% of total farm area has provided the highest benefits in the integrated mangrove shrimp model. In this study, we re-examine the benefits of forest cover on the survival and yield of tiger shrimp (Penaeus monodon) in the integrated mangrove shrimp farming systems in Ca Mau province, Vietnam. The study found positive linear correlations of log transformed survival and yield of tiger shrimp with forest cover of the forms: Ln (survival) = − 1.39 + 0.038 × forest coverage (r2 = 0.22; p value = 0.0007); Ln (yield) = 3.55 + 0.026 × forest coverage (r2 = 0.16; p value = 0.004). The households with high forest cover (i.e., > 45%) also had 1.07 ± 0.29 and 1.39 ± 0.36 (CI 95%, p value = 0.000) kg ha−1 higher yield per night harvest than those with medium and low forest cover, respectively. As a result, households with high forest cover have higher benefits than those with lower forest cover. Our findings together with previous published studies lead to the recommendation that farmers maintain mangroves in farming systems for better economic and environmental benefits. [ABSTRACT FROM AUTHOR]

Despite an expansion of production, pangasius farmers have experienced economic challenges in Vietnam. The aim of this study was to identify optimum economic alternatives for pangasius farmers. A single-stage stochastic frontier analysis was used to estimate the economic efficiency of pangasius farms and investigate the farm size–economic efficiency relationship using cross-sectional data collected on Vietnamese pangasius farms. The study found a nonlinear relationship between farm size and economic efficiency, with economic efficiency increasing until the farm area reached a threshold of 26.9 ha, then falling due to transaction and agency costs under asymmetric information. The farming experience of the decision-makers negatively affected efficiency. Similar to previous studies, we found feed and fingerling costs were essential input factors for farms. Based on these results, we recommend three strategies for improving the economic efficiency of farms are: providing timely market information to farmers; determining the optimal farming scale depending upon the specific farmer's available resources; and using a good quality of fingerlings and feed. [ABSTRACT FROM AUTHOR]

Countries increasingly use access and benefit‐sharing laws as a tool for the conservation and sustainable use of biological resources and associated traditional knowledge. These laws generally require the recipient of resources/knowledge to obtain the provider country's prior informed consent before collection, use or transfer and to share the benefits from their use with the provider. The aim of this literature review is to comprehensively analyse access and benefit‐sharing laws and literature about the top five aquaculture‐producing countries – China, India, Indonesia, Viet Nam and Bangladesh – to identify research trends and gaps in relation to accessing and sharing the benefits of aquaculture genetic resources and associated traditional knowledge. Using a systematic quantitative literature review methodology, we found only 5% of the literature examined the implications of access and benefit‐sharing for aquaculture and these only related to publications about India's arrangements. While the other countries had literature about their legal measures and literature about informal genetic resource sharing practices in aquaculture, none of them connected the two research topics. None of the countries had literature analysing the implications of access and benefit‐sharing in relation to traditional knowledge associated with aquaculture. We conclude that given these are the top global producers accounting for up to 80% of all aquaculture products, urgent research is needed to fill the literature gaps to assess whether access and benefit‐sharing as a legal/policy tool is achieving conservation and sustainable use goals for aquaculture genetic resources. [ABSTRACT FROM AUTHOR]

The growth in global aquaculture production may address the lack of sustainability in wild fisheries, alleviate poverty in rural and coastal areas, and help meet the worldwide increase in demand for animal protein. However, there is an ongoing debate about the severity of the environmental impact of aquaculture production. Investing in new high-tech production systems can address both productivity growth and the environmental externalities, but high investment costs hinder adoption of high-tech production methods. We investigate the potential of a payment for environmental services program easing access to capital for producers to increase willingness-to-invest in more sustainable aquaculture practices in Vietnam. We conducted two discrete choice experiments to explore the supply and demand side of the policy. First, we elicited the public's willingness-to-pay to reduce the environmental impact of conventional shrimp aquaculture, and second, we elicited farmers willingness-to-accept a credit subsidy to invest in high-tech production methods. Our results show that the public care about reduced environmental impacts, while farmers strongly prefer increased productivity. Furthermore, the public's willingness-to-pay for reduced environmental impacts exceeds producer's willingness-to-accept a subsidy to invest under most scenarios. This implies a potential for more sustainable aquaculture production in Vietnam. [ABSTRACT FROM AUTHOR]

The Mekong River is a vital fisheries resource supporting millions of people in mainland Southeast Asia. However, numerous threats have the potential to negatively impact fish populations in this region including overfishing, pollution, climate change and increased urban, agriculture and upstream hydropower development. Although a few studies have examined the population genetic structure of fishes within the upper Mekong River, no known studies have explored that of fishes within the Mekong Delta (MD). Here, we examine the population structure of an important food fish within the MD, Polynemus melanochir, using a panel of 1735 single nucleotide polymorphisms (SNPs) generated by restriction site-associated DNA (RAD) sequencing across eight locations on the Tien (Mekong) and Hau (Bassac) Rivers in Vietnam. Pairwise FST values, principal component analysis and Structure analysis all indicate high levels of gene flow among the sites sampled across the MD. In contrast to the lack of genetic structure, high levels of relatedness were found, including 26 putatively related pairs, as well as an effective population size (Ne) of less than 500 across the MD. While panmixia indicates that fragmentation of this population is not presently an important threat, a low Ne estimate suggests this species may not be resilient to long-term environmental changes in the MD. The reliance on P. melanochir as a food resource may be contingent on management and mitigation of low effective population sizes. [ABSTRACT FROM AUTHOR]

This study investigated the determinants of the adoption of improved rice-fish farming systems in the Mekong delta to support policy making, agricultural land-use planning and extension of integrated rice-fish farming. Recently these systems have been referred to as adaptations to climate change, while traditional rice-fish systems have often been abandoned. In 2006, we carried out surveys among 94 farmers either practising rice monoculture or having an improved rice-fish system. We analysed data among others with binary logistic regression and simulated adoption by using fuzzy logic. Per capita and per hectare incomes of households practising rice-fish systems were nearly double, while their farm size was 1.3 times larger than that of the rice monoculture farms. Households with larger homesteads, i.e. neighbouring irrigated fields and ponds, better access to financial capital and more know-how of rice and fish culture and their integration, were more likely to adopt rice-fish systems. Previously identified drivers and factors for adoption, such as an appropriate agro-ecological context and the farmer's education and training level, were confirmed. Promoting rice-fish systems needs participatory extension and research approaches for sustainable agriculture strategies such as integrated pest management (IPM) in which farmers, trainers and researchers optimize technologies in constantly changing contexts. [ABSTRACT FROM AUTHOR]

This study assesses the use of pesticides and attitude to pest management strategies among rice and rice-fish farmers in Cn Th and Tin Giang provinces of the Mekong Delta, Vietnam, in 2007. A comparison is made to a similar study in 1999, in order to identify changes in patterns of pesticide use and possible influences of integrated pest management (IPM) programmes and brown planthopper (a major pest) outbreaks. One hundred and twenty farmers used 66 different pesticides, similar to the 64 pesticides recorded as being used in the 1999 survey. Nine of the 10 most popular pesticides in 2007 were the same as those found to be popular in 1999. Insecticides are used by 73–95% of the farmers, which is the most commonly employed type of pesticide. The number of applications of both herbicides and fungicides has more than halved since 1999 for all farmers, while insecticide applications has doubled for IPM farmers (those with prior training in IPM methodology). Similarly, the average dose of active ingredient (a.i.) of insecticides per crop has decreased slightly for non-IPM rice farmers, while it has more than doubled among IPM farmers, resulting in almost the same amount of a.i. per crop for all groups of farmers (insecticides 0.6, fungicides 0.5, and herbicides 0.3 kg a.i. ha−1 crop−1). Overall, the results indicate a temporal trend for more selective use of pesticides and an increased awareness among non-IPM farmers of the negative side effects of pesticide use. [ABSTRACT FROM PUBLISHER]

Purpose: Intensive striped catfish production in the Mekong Delta has, in recent years, raised environmental concerns. We conducted a stakeholder-based screening life cycle assessment (LCA) of the intensive farming system to determine the critical environmental impact and their causative processes in producing striped catfish. Additional to the LCA, we assessed water use and flooding hazards in the Mekong Delta. Materials and methods: The goal and scope of the LCA were defined in a stakeholder workshop. It was decided there to include all processes up to the exit-gate of the fish farm in the inventory and to focus life cycle impact assessment on global warming, acidification, eutrophication, human toxicity, and marine (MAET) and freshwater aquatic ecotoxicity (FWET). A survey was used to collect primary inventory data from 28 farms on fish grow-out, and from seven feed mills. Hatching and nursing of striped catfish fingerlings were not included in the assessment due to limited data availability and low estimated impact. Average feed composition for all farms had to be applied due to limitation of budget and data availability. Results and discussion: Feed ingredient production, transport and milling dominated most of the impact categories in the LCA except for eutrophication and FWET. Most feed ingredients were produced outside Vietnam, and the impact of transport was important. Because of the screening character of this LCA, generic instead of specific inventory data were used for modelling feed ingredient production. However, the use of generic data is unlikely to have affected the main findings, given the dominance of feed production in all impact categories. Of the feed ingredients, rice bran contributed the most to global warming and acidification, while wheat bran contributed the most to eutrophication. The dominance of both was mainly due to the amounts used. Fishmeal production, transport and energy contributed the most to MAET. The biggest impacts of grow-out farming in Vietnam are on eutrophication and FWET. Water nutrient discharge from grow-out farming was high but negligible compared with the natural nutrient content of the Mekong River. The discharge from all grow-out farms together hardly modified river water quality compared with that before sector expansion. Conclusions: Feed production, i.e. ingredient production and transport and milling, remains the main contributor to most impact categories. It contributes indirectly to eutrophication and FWET through the pond effluents. The environmental impact of Pangasius grow-out farming can be reduced by effectively managing sludge and by using feeds with lower feed conversion ratio and lower content of fishery products in the feed. To consider farm variability, a next LCA of aquaculture should enlist closer collaboration from several feed-milling companies and sample farms using their feeds. Future LCAs should also preferably collect specific instead of generic inventory data for feed ingredient production, and include biodiversity and primary production as impact categories. [ABSTRACT FROM AUTHOR]

The striped catfish ( Pangasianodon hypophthalmus) (Sauvage), also referred to as tra catfish or sutchi catfish, farming sector is an icon of aquaculture development in Vietnam and globally. Over a decade it has developed from a humble backyard operation to one that currently accounts for the production of over one million tonnes, employing over 180 000 rural poor, and generating an export income exceeding US$ 1.4 billion (2010). It accounts for the highest average production, ranging from 200 to 400 t ha crop, ever recorded for the primary production sector. The system is integrated and incorporates seed production, fry to fingerling rearing and grow-out, and is concentrated in a few provinces in the Mekong Delta (8°33′-10°55′N, 104°30′-106°50′E), along two branches of the Mekong River. In essence, perhaps, the initial trade restrictions on catfish exports to the USA provided the impetus and then the associated developments from 2002 to 2005 of the sector to a great extent in seeking new markets. The explosion of tra catfish farming has resulted in many competitive sectors challenging this 'tra catfish' invasion into a globalized market. These confrontations still exist with many instances of attempts to discredit the sector and discourage international consumers. However, the Vietnamese catfish sector is resilient and has managed to withstand such pressures and continues to thrive. This paper reviews the development of catfish farming in the Mekong Delta, its current status and what is required to sustain it as a major food source and livelihood provider. [ABSTRACT FROM AUTHOR]

To reveal farmers' motives for on-farm diversification and integration of farming components in the Mekong Delta, Vietnam, we developed a fuzzy logic model (FLM) using a 10-step approach. Farmers' decision-making was mimicked in a three-layer hierarchical architecture of fuzzy inference systems, using data of 72 farms. The model includes three variables for family motives of diversification, six variables related to component integration, next to variables for the production factors and for farmers' appreciation of market prices and know-how on 10 components. To obtain a good classification rate of the less frequent activities, additional individual fine-tuning was necessary after general model calibration. To obtain the desired degree of sensitivity to each variable, it was necessary to use up to five linguistic values for some of the input and output variables in the intermediate hierarchical layers. Model's sensitivity to motivational variables determining diversification and integration was of the same magnitude as its sensitivity to market prices and farmers' know-how of the activities, but less than its sensitivity to labour, capital and land endowment. Modelling to support strategic decision-making seems too elaborate for individual farms, but FLM will be useful to integrate farmers' opinions in strategic decision-making at higher hierarchical levels. [ABSTRACT FROM AUTHOR]

Abstract  Rural aquaculture is the farming of aquatic organisms with extensive and semi-intensive husbandry practised by small-scale rural households for their consumption and income. From a field survey in Southeast Vietnam, using enterprise budget analysis and nonparametric tests with indices of change, adoption, and agreement, this study justifies that rural aquaculture is a good option for rural development, making an important contribution to farm income with a high adoption rate among poor farmers. Fish farmers have gained an increased level of satisfaction by means of fish culture production growth along with corresponding economic gains. This enterprise continues to play an increasing important role in their livelihoods and has potential to develop further in the area. [ABSTRACT FROM AUTHOR]

Vietnam is the largest producer for the export of striped catfish. Traditionally striped catfish production in the Mekong Delta took place in integrated agriculture-aquaculture systems, but has shifted recently to intensive systems to meet increasing export demands. A recent study quantified the environmental impact of intensive striped catfish production in Vietnam. Another did the same for integrated systems. Both studies used life cycle assessment, covered similar environmental impact categories, and were roughly matched in the production stages included. However, an environmental comparison of both systems has not been made so far. The objective of this paper is to make a comparative life cycle assessment of striped catfish production in intensive and integrated systems. The comparison was based on existing life cycle assessments on these systems, but their methodological choices and data had to be aligned. The results show that striped catfish production in intensive systems contributes considerably more to seven of the nine assessed impact categories (global warming, ozone depletion, acidification, eutrophication, photochemical oxidation, human toxicity, freshwater ecotoxicity, marine aquatic ecotoxicity, fossil depletion). Only contributions to eutrophication and freshwater ecotoxicity were higher for the integrated systems than for the intensive systems. In both systems, grow-out fish farming contributes most to eutrophication and freshwater ecotoxicity, whereas feed production contributes most to all other impact categories. The environmental performance of integrated striped catfish production is convincingly better in most impact categories. This raises questions about whether (elements of) these systems can be used to mitigate the environmental impact of intensive striped catfish production. [ABSTRACT FROM AUTHOR]