Fish jumping across the water at a fish farm in Satkhira District, Bangladesh. Photo by Andrew Aitchison / In pictures via Getty Images.
Shrimp cultivation as climate adaptation in coastal Bangladesh
As rising sea levels contribute to increasing salinity in coastal Bangladesh, farmers are adapting by converting rice fields into saltwater ponds for shrimp cultivation. While this transition encourages in situ adaptation and bolsters against local demand shocks, it can also create negative externalities for nearby agricultural plots, highlighting the need for smart policies that safeguard both shrimp and rice farmers.
Climate models predict that Bangladesh faces severe climate change risk, which threatens to undermine the country's recent successes in growth, poverty reduction and human development. One of the ways in which climate scientists expect this risk to manifest is through increased groundwater and river salinity, caused in part by climate change-induced sea-level rise.
In coastal districts of southwestern Bangladesh, landowners and operators have responded by flooding plots of land previously used for rice cultivation with this newly saline water to convert them into ghers, or shallow saltwater ponds, that can be used for the cultivation of shrimp and other saltwater fish.
Note: Rice plot and pond separated by an irrigation ditch. Picture provided by the authors.
Why might shrimp cultivation hold promise?
The transition from rice farming to shrimp cultivation allows people to adapt in situ to changing climate conditions, rather than making the risky choice of migrating to cities for work. Encouraging in situ adaptation can be an important objective for policymakers, as the large-scale movement of people into cities may lead to overcrowding, congestion or other unfavourable outcomes and challenges.
Second, while rice farmed in this region is largely sold in local or regional markets, 20-40% of shrimp produced in Bangladesh is exported. Because demand for shrimp is influenced by international markets, rather than driven by domestic consumption, switching from rice farming to shrimp cultivation may act as a form of insurance.
However, it is important to note that shrimp cultivation is unlikely to be a silver bullet against climate change in this region. It may be more volatile than rice farming due to disease outbreaks and poor cultivation techniques.
Additionally, shrimp cultivation requires less manual labour than rice farming, which may lead to lower wages or employment levels among casual labourers in coastal settings.
Community perceptions about rising salinity and production spillovers
As part of a project on shrimp farming supported by the International Growth Centre, we conducted 10 focus group discussions and surveyed 739 households in a rural coastal region of Bangladesh, where salinity levels are expected to rise, to gain a better understanding of the context behind this form of climate adaptation.
Figure 1: Location of surveyed unions in Bangladesh
Notes: Surveys were carried out in the southwestern districts of Khulna and Satkhira (shown in green). Sampled unions (shown in orange) were selected from among those with a high share of both agricultural workers and aquaculture workers. Unions are the smallest rural administrative units in Bangladesh. Figure generated by the authors.
We noticed that focus group discussants reported high levels of concern about the changing climate and believed that future increases in salinity will lead to lower yields for current rice varieties. As one discussant from a village with both shrimp cultivators and rice farmers explained:
“Salinity is increasing after the seasons change and the temperature rises. And this is not just happening here in our salt areas, it is happening in the whole area because of increased temperature, and that is causing salinity.”
Discussants expect that this will be more extreme for those living in areas where agricultural plots have been converted to saltwater ghers, which suggests that they are aware of negative externalities – such as production spillovers, which will affect those who remain in agriculture if shrimp cultivation leads to increased saline intrusion.
Cultivators of shrimp ponds told us how the process of spillovers worked in practice: “The situation of the land deteriorated for one to two years as salt water entered the land,” said one farmer.
Note: Shrimp for sale at a market in Satkhira, Bangladesh. Picture provided by the authors.
Farmers are concerned about climate change, but face barriers to converting land
Survey findings echoed the climate concerns expressed by the focus group discussants. When asked whether ‘climate change is a very serious threat, a somewhat serious threat, or not a threat at all to the people in this country in the next 20 years’, 78% of survey respondents chose ‘very serious threat’. They were not only concerned about climate change, but also cognisant of the spillover risks from the adaptation behaviours of their neighbours.
In our sample, 95% of respondents working in agriculture expect an increase in salinity in their plot if neighbouring plots are converted to saltwater ponds for shrimp farming. Likewise, 98% of respondents expect the yields from their rice seeds to decline in that scenario.
In our sample, shrimp cultivators reported higher incomes than those who operate rice paddies, despite the groups being similar in age, education and gender. One friction preventing farmers from making the switch appears to be the costs of converting land from agriculture to shrimp plots. The average respondent estimated that it would take more than three weeks to convert a rice field into a gher. Only 18% of those surveyed currently have enough savings to cover the conversion costs, though 75% believe they would be able to take out a loan for that purpose.
Balancing adaptation policies to safeguard livelihoods
Bangladesh’s coastal districts are already adapting to rising salinity by converting rice fields to saltwater ghers for shrimp cultivation. However, our research suggests that adaptation policy should balance two priorities: mitigating spillover harms on the remaining rice producers (through the introduction of salinity-tolerant varieties and embankment maintenance) while easing barriers for those who could benefit from switching (through targeted credit, phased cost-sharing, and technical support).
Supporting both groups – households who adopt shrimp farming and those who remain in agriculture – will be critical to safeguarding livelihoods as the effects of climate change intensify.