The area and output of freshwater shrimp increased markedly up to about 2008. However, production has declined significantly in the past decade due to chemical pollution from neighbouring HYV rice paddies, reduction in flood levels (the flood peak in 2015 was the lowest in 100 years), and unstable market prices. The area of shrimp ponds in An Giang peaked at 650 ha in 2007 and fell to 214 ha by 2016, while the average yield fell sharply from over 2 tons/ha in 2012 to be less than 1 ton/ha in 2016 (Fig. 17.8 above). With this decline in area and yield, total production in An Giang fell from 1334 tons in 2008 to just 194 tons in 2016. The same trends have occurred in both An Giang and Dong Thap Provinces.^Footnote7

Rice combined with brackish-water shrimp was observed in five coastal provinces as early as the 1930s (Nguyen, H. C. 1994). In 1984, there was about 5000 ha of rice-shrimp farming (Xuan and Matsui 1998). At this time, the yield of shrimp averaged 640 kg/ha and the yield of rice ranged from 3.5 to 4.0 tons/ha (Xuan and Matsui 1998). In 2000, the total area of rice-shrimp was 71,000 ha, distributed across five coastal provinces: Ben Tre, Soc Trang, Bac Lieu, Ca Mau, and Kien Giang. This had increased to 153,000 ha in 2014 (USAID 2016). These semi-intensive rice-shrimp systems include one crop of wet-season rice and one or two crops of tiger shrimp or white-leg shrimp (USAID 2016). This system is very common in Soc Trang, Ca Mau, Kien Giang, Ben Tre, and Tra Vinh Provinces. Total brackish-water shrimp production was 65,000 tons with yields ranging from 300 to 500 kg/ha (USAID 2016). Preston and Clayton (2003) found that farmers’ incomes had improved significantly from adopting this system.

The rice-shrimp systems have several technical problems that threaten their sustainability. Nutrient use in rice-shrimp systems is less efficient than in dedicated shrimp grow-out ponds, causing low shrimp survival rates and low production (Dien et al. 2018). Leigh et al. (2017) found water temperature and salinity were too high in the dry season and dissolved oxygen was too low, causing low survival rate and low shrimp production. The rice crop was also affected adversely by high salinity levels (Leigh et al. 2017). Although rice-shrimp systems are economically and environmentally viable, farmers have tended to switch to intensive shrimp production systems (Preston and Clayton 2003).

Climate change poses new risks to rice-shrimp farming systems. Early saline water intrusion in November negatively affects rice yields while contributing to an accumulation of soil salinity over time (Preston and Clayton 2003; ACIAR 2016). The impacts of climate change have increased in recent years. Saline intrusion due to drought events occurs more frequently. The historical drought event in 2015 caused severe damage to rice, vegetables, flowers, fruit trees, livestock, buffaloes, cattle, and small fishponds. The coastal provinces were most affected, with rice, fruit, and aquaculture taking the brunt of the impact.

Rice-based farming systems in the Mekong Delta have been transformed over the last three decades due to farmer initiatives and government policy. Facing an urgent need to boost rice production after 1975, the government increased investment in water control and irrigation and promoted the intensification of rice farming through green revolution technology, leading to widespread adoption of double- and triple-cropping systems. With the expansion of irrigation and increased cropping intensity, the area of rice in the Delta increased from around 2.0 million ha in the immediate post-war decade to 3.2 million ha in 1995 and 4.3 million ha in 2016. The yield of the main wet-season (autumn) crop increased from about 2 t/ha in 1975 to 3.8 t/ha in 1995 and 5.3 t/ha in 2016 due to better water management, use of HYVs, and greater use of fertilisers. Total production of paddy rice was only about 4 million tons in 1975, increasing threefold to 12.8 million tons in 1995 and doubling again to 24.2 million tons in 2016. The increase is attributable in equal measure to the increase in planted area and the increase in yields. From being a net importer of rice in the 1970s and 1980s, Vietnam exported 1.4 million tons in 1989 following the first phase of intensification and market reforms. In 2016, exports totalled 4.5 million tons worth USD 2 billion, 90% of which was produced in the Delta. By any standard, this has been an amazing economic transformation.

However, the focus on rice intensification has shifted since 2000 as the impacts on farmer livelihoods and the environment have become apparent. Locking farmers into producing low-quality rice for the export market has not provided them with adequate returns, especially as both domestic and global demand have shifted in favour of higher-quality rice and more diverse diets. Specialisation in continuous rice production has also restricted the dietary diversity of rural households. Intensive use of fertilisers and pesticides has led to soil and water pollution and reduction in wild food supply. Moreover, the “total management” of hydrology in the Delta has had major impacts on water flows, sedimentation processes, aquatic species, and land-use options. The Delta is also highly vulnerable to the effects of climate change, including sea-level rise, increased drought and flooding, and saline intrusion, the latter affecting up to half the surface area.

In response, the government has progressively relaxed its restrictions on the use of paddy lands—originally conceived to achieve food security and maintain export earnings. Hence, rice-based farming systems have become more diversified in the last two decades, with the increased use of paddy lands for non-rice field crops, orchards, and freshwater and brackish-water aquaculture. Irrigated dry-season horticultural crops and productive and profitable orchards now abound in the Alluvial Floodplain. While the traditional inland fish catch has declined, the production of freshwater fish in ponds, especially local catfish, has developed into a major export industry in the upper Delta. Freshwater shrimp, however, after a rapid increase since 1990, appears to be in decline. In the Coastal Complex and the Ca Mau Peninsula, brackish-water shrimp culture has had a longer and more successful history, though it is facing challenges due to disease outbreaks, market fluctuations, and climate change.

The most recent indication of the shift in policy was the November 2017 resolution in support of sustainable development strategies for the Delta. These strategies include (1) promotion of high-quality rice, (2) reduction in the area planted to rice, (3) further diversification of farming systems, and (4) promotion of agro-ecological and organic agriculture. Targets have been set to increase the quality rather than the volume of rice and to diversify rice-based farming systems to make the best use of each agro-ecological zone in the Delta. Even traditional floating rice is being encouraged in the remaining deep-flooding pockets. Reduction in the area planted with rice is intended to help counter the overuse of chemicals in the paddy field ecosystem while opening further opportunities for the diverse range of crop, livestock, and aquatic products that are increasingly in demand in Vietnam’s cities. Promotion of integrated (or agro-ecological) rice-based farming systems is intended to provide the basis for more profitable and sustainable rural livelihoods in the Delta, with greater adaptability to changing markets and climate.