Over the last three decades, shrimp farming in saline and semi-saline ponds has expanded rapidly and become a dominant livelihood strategy in many coastal areas. The coastal region, comprising 19 districts and home to nearly 38 million people, relies heavily on agriculture, aquaculture, and small-scale fisheries. Today, communities on the frontline of climate change are struggling with rising salinity and declining freshwater availability, making the transition toward resilient and well-managed aquaculture more critical than ever for supporting fragile livelihoods.

Salinity intrusion refers to the movement of saline water into freshwater systems such as rivers, soils, and aquifers, causing profound physical and chemical changes. In Bangladesh, this process has accelerated due to natural drivers such as sea-level rise, tidal surges, and reduced dry-season river flows, alongside human-induced pressures including upstream freshwater diversion, poor water governance, unsustainable land-use practices, and inadequate regulation and management of coastal aquaculture systems. During dry seasons, when river discharge is insufficient to repel seawater, the saline front advances further inland, increasing both surface and groundwater salinity.

According to the Soil Resources Development Institute (SRDI), saline-affected land in Bangladesh expanded from 0.83 million hectares in 1973 to over 1.056 million hectares by 2019, an alarming increase that underscores the persistence and severity of the problem. This expanding salinity footprint directly threatens aquaculture systems that depend on stable water quality conditions.

Key Impacts on Aquaculture and Livelihoods
Shrimp aquaculture initially generated high to moderate profits, attracting farmers to convert agricultural land into saline ponds. However, over time, socio-economic benefits have declined due to frequent viral infections, disease outbreaks, poor drainage, and rising soil and water salinity across entire farming landscapes. Erratic rainfall, temperature stress, and increasing siltation of riverbeds have further reduced the suitability of coastal environments for both crops and aquaculture.

As a result, many farmers are now attempting to revert to paddy–aquaculture integrated systems, which are more socially acceptable, environmentally friendly, and better aligned with the delta’s natural ecology. In this climate-stressed region, smallholders increasingly seek resilient livelihood strategies capable of adapting to rapid biophysical and socio-economic changes.

The major impacts of salinity intrusion on aquaculture include:

Reduced Productivity: Elevated salinity levels severely affect freshwater fish species such as carp and tilapia, leading to high mortality rates and reduced overall aquaculture output.

Land Degradation: Unplanned and poorly managed conversion of farmland into saline aquaculture ponds can degrade soil structure, reduce fertility, and increase waterlogging, making land unsuitable for future agricultural use.

Increased Livelihood Risk: Inadequate institutional support and unequal access to resources in brackish water aquaculture systems can exclude marginal farmers, often resulting in land dispossession and loss of income for poorer households.

Disease Vulnerability: Salinity fluctuations weaken the immune systems of aquatic organisms, increasing susceptibility to disease and undermining long-term aquaculture sustainability.

Impacts on Communities and Food Security
The transition toward saline aquaculture systems has also reshaped rural society. Wealthy and influential actors often benefit disproportionately from shrimp farming, while traditional farmers and laborers face declining employment opportunities and widening income inequality.

Salinity-induced scarcity of drinking water, reduced crop production, and loss of grazing land for livestock have intensified health and nutritional challenges. Many households are forced into seasonal or permanent migration in search of alternative livelihoods. Declining availability of freshwater fish, milk, and vegetables has further weakened food and nutrition security in coastal communities.

Although some areas have adopted salinity-tolerant crops and integrated farming systems, the overall trend points toward increasing vulnerability, particularly for landless and smallholder households.

Drivers of Salinity Intrusion
The drivers of salinity intrusion in coastal Bangladesh are both climatic and anthropogenic. Climate change has intensified sea-level rise, altered monsoonal patterns, increased average temperatures, and heightened the frequency and intensity of cyclones and storm surges. These processes contribute to embankment breaches, tidal flooding, land erosion, and widespread saline water inundation.

Human interventions such as reduced upstream river flow due to dam construction, poorly planned embankments, deforestation, weak governance, and inadequate regulation and monitoring of coastal resource use have compounded these impacts. Cyclones such as sidr (2007) and Aila (2009) caused extensive and long-lasting salinization of agricultural lands, freshwater ponds, canals, and rivers, with consequences that persist to this day.

For many farmers, aquaculture remains a vital livelihood strategy, but its sustainability increasingly depends on improved management, governance, and climate-resilient practices.

Professional Management and Adaptation
Despite these challenges, the industry is moving toward modern, resilient technologies. Mismanagement is being replaced by scientifically informed strategies:

Automated Monitoring: Adoption of real-time IoT sensors allows farmers to manage tidal intake and prevent “salinity shocks”.

Advanced Systems: Implementing biofloc and closed-loop recirculating systems (RAS) minimizes the need for external water exchange.

Diversified Models: The “Golda-Paddy-Vegetable” model, using salt-tolerant varieties, stabilizes the farm ecosystem.

Infrastructure: Strengthening polder embankments and improving drainage canals are essential to prevent waterlogging.

By adopting optimal stocking densities and biosecurity measures, aquaculture improves its resilience and sustainability. Addressing salinity contributes to SDG 2 (Zero Hunger), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 14 (Life Below Water).

The Sundarbans Context: Risk and Opportunity
Aquaculture in the Sundarbans and its surrounding islands is particularly vulnerable to climate change. Cyclones and storm surges frequently inundate fishponds with saline water, causing dyke failure, mass fish mortality, disease outbreaks, water quality deterioration, and escape of stocked species. Farmers often rely on short-term coping mechanisms that offer limited protection.

Long-term resilience requires scientifically informed adaptation strategies that reduce negative impacts while enhancing positive outcomes. As salinization continues, some areas may shift toward regulated brackish water aquaculture systems. However, such transitions must be carefully managed to avoid repeating past mismanagement practices and ensure proper planning, environmental safeguards, social equity, and sustainable seafood production.

Salinity intrusion is a present and escalating challenge for coastal livelihoods. Addressing it requires integrated planning, stronger governance, and climate-resilient aquaculture practices. With decisive action and improved management, Bangladesh can protect its coastal food systems and ensure sustainable seafood production for the future.

Md. Shofiullah
Student, Department of Oceanography
Noakhali Science and Technology University

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