[Commentary] Is expansion of aquaculture in the Indian Sundarbans an ecological threat or a pathway to sustainable development?

Image shows aquaculture farms in Sundarbans
  • The rapid expansion of aquaculture in the Indian Sundarbans is bringing huge profits to some while short-changing the local communities of their right to a sustainable future.
  • Salinisation is not the foremost driver of rapid aquaculture expansion in the Sundarbans Biosphere Reserve.
  • In this commentary, Shaberi Das and Sugata Hazra discuss the economic incentives that lead to the conversion of agriculture to aquaculture in the Indian Sundarbans.
  • The views in this commentary are that of the authors.

Aquaculture is a rapidly expanding sector globally, with India being the second-largest producer of aquaculture resources and contributing approximately 6.3% to global aquaculture production. The state of West Bengal, with its long, serrated coastline, has a vast potential for aquaculture. It is the largest producer of tiger prawns in the country, most of which are cultured in the rapidly expanding aquaculture areas of the Sundarbans Biosphere Reserve (SBR).

Is the expansion of aquaculture, in response to growing market demand and profitability, a threat to this critically vulnerable coastal area? Or is it a means for sustainable development of the local communities struggling to adapt to accelerating climate change impacts?

The SBR is a unique mangrove forest comprising a network of mudflats and low-lying islands at the confluence of the populous Ganges river delta in West Bengal, India, with the royal Bengal tiger as its flagship species. It is a UNESCO World Heritage Site, spanning 9,630 sq. kms. across core and buffer forest areas and a transition zone. As many as 4.43 million people inhabit the transition zone (5,367 sq. kms. area) and traditionally practice rainfed agriculture, artisanal fishing and forest collection for their subsistence.

Large-scale clearance of mangrove areas in the 19th century transformed the Sundarbans into a settlement for revenue generation by the colonial regime. Freshwater flow to the region diminished with time so that river water, and even the groundwater in many places, is brackish-to-saline.

While some farmers traditionally practiced freshwater aquaculture in backyard ponds, brackish water aquaculture (BWA) proliferated low-lying areas adjacent to river banks and creeks when globalisation brought the international demand for prawns to the doorstep of the mangrove forest.

Map indicating that most of the aquaculture farm clusters in the region are concentrated in areas far removed from the seafront. The Dampier-Hodges line represents the extent of the mangrove forest as mapped in 1830. Photo courtesy School of Oceanographic Studies, Jadavpur University.
Map indicating that most of the aquaculture farm clusters (in blue) in the region are concentrated in areas far removed from the seafront. The Dampier-Hodges line represents the extent of the mangrove forest as mapped in 1830. Photo courtesy School of Oceanographic Studies, Jadavpur University.

A range of socioeconomic and environmental drivers, supported by a significant lack of vision for sustainable development, has led to the rapid growth of BWA at the expense of over 1,000 hectares of mangrove forest, 2,322 hectares of eco-sensitive mudflats and 2,4000 hectares of multi-crop agricultural land, defying coastal regulations.

While some part of the land conversion can be attributed to the terrible legacy of cyclone Aila (2009), which rendered agricultural lands in some cyclone-affected areas unfit for cultivation for several years, salinisation is not the foremost driver of rapid aquaculture expansion in the SBR.

The promise of higher profitability from commercial aquaculture enticed farmers to illegally convert their agricultural fields to aquafarms.

In the last few decades, erratic monsoon alongside temperature rise on land and sea, frequent cyclones and floods, a high rate of coastal erosion, and the rising cost of fertilisers and farming, have gradually reduced agricultural productivity and driven more and more farmers to adapt by shifting to aquaculture.

A recent study by a team from India’s Jadavpur University along with researchers from Sweden and the U.K., has concluded that economic profitability to the tune of Rs. 1,50,000 to 4,85,000 (US$ 2,023-6,540) per hectare per year, is the main incentive for this rapid expansion, challenging the myth of salinity being the primary driver.

Though there are evidences of increasing salinisation and degeneration of mangroves in parts of the SBR, particularly in the sea-facing southeastern and southwestern parts of the mangrove islands (as indicated in Samanta et al., 2022), this can hardly explain why the majority of brackish water farms are located more than 100 km away from the seafront and close to the market center of Kolkata (as discussed by Giri et al., 2021).

Read more: Scientists raise caution as mangroves erode faster along the Bengal coastline

The SBR now supplies aquaculture products to new international market segments like organic shrimp. Though seemingly lucrative, commercial aquaculture critically undermines several environmental and socioeconomic targets of the Sustainable Development Goals (SDGs). Brackish water monoculture uses indigenous wild post-larvae (seeds) collected from rivers and creeks by marginal fisherwomen, generating a large by-catch and destroying 400 different species, including prawns, fishes, crabs and molluscs-and often exposing the collectors to human-animal conflict.

Intensive and extensive seed collection for the expansion of this culture and the salinisation of agricultural land adjacent to brackish water aquafarms violates SDG 15, which aims to protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, reverse land degradation and halt biodiversity loss. Several pieces of research have unequivocally indicated that the degradation of the natural landscape and industrial-scale growth of aquaculture plots have led to a substantial increase in global greenhouse gas emissions (Yuan et al. 2019; Arneth et al. 2021).

Leaching of antibiotics and other pollutants from aquafarms into the environment also directly contradicts SDG 14, which calls for reducing marine pollution. A large-scale shift to semi-intensive or intensive brackish water cultures of exotic species like the white leg shrimp (L. vannamei) and African catfish (C. gariepinus) in freshwater ponds endangers the critically sensitive Sundarbans ecosystem to satisfy the profit-making appetite of major aquaculture farmers and external investors and the government’s vision of a ‘blue economy’.

But will this thrust for a ‘blue economy’ ultimately oppose the green growth promised at the United Nations Sustainable Development Summit 2015 in New York?

Expanding aquaculture farms in the Sundarbans Biosphere Reserve.
Expanding aquaculture farms in the Sundarbans Biosphere Reserve. Photo by School of Oceanographic Studies, Jadavpur University

Several laws such as the West Bengal Land Reforms Act, 1955, West Bengal Inland Fisheries (Amendment) Act, 1993, and the Coastal Aquaculture Authority Act, 2005, have outlawed the conversion of agricultural and forest land for aquaculture in the coastal areas. How then does the expansion of aquaculture at the expense of sustainable development and conservation continue unabated?

The answer lies in the government’s tacit support and significant political and commercial clout in commercial aquaculture. Lukewarm enforcement of existing laws becomes the most potent instrument for promoting profitability at the cost of the environment and the well-being of the local communities.

What then is the way forward? Stricter enforcement of existing laws to discourage land conversion for aquaculture and wild seed collection, encouraging existing aquaculture farms to use more sustainable farm management practices like traditional and improved-traditional polyculture of shrimps, finfish and crabs, and manually stocking farms with seeds acquired from other state hatcheries are recommended.

Additionally, skill development for non-farm-based livelihoods, rainwater harvesting to enhance agricultural productivity and cropping intensity, and incentives for Joint Forest Management can also arrest further aquaculture expansion.

Read more: Grasses spur mangroves to grow in an erosion-riddled Sundarbans patch

The Calcutta High Court, in a remarkable judicial order dated December 10, 2020, called for the formation of a two-member committee led by a senior officer of the Indian Police Service to immediately halt the illegal conversion of forest land into aquaculture farms, resorts and adventure sports outlets in the SBR, acknowledging the unregulated expansion of aquaculture as a massive failure of governance.

While sources indicate that the committee has been partly successful in its endeavours, neither is the preliminary report of its activities (ordered to be presented before the Court in December 2021) available in the public domain nor have fresh executive orders to halt aquaculture expansion been issued, leaving one to wonder how long the administration will continue to privilege the profit motive over sustainable development in the critically vulnerable Sundarbans, especially after the state forest department’s post-Amphan (2020) pledge to plant 50 million mangroves in the SBR each year.


Shaberi Das is a researcher and Sugata Hazra is a professor in the School of Oceanographic Studies, Jadavpur University, Kolkata.


Calcutta HC forms committee to stop illegal conversion of forest land in Sunderbans. (2020). Deccan Herald.

Giri, Sandip, Daw, Tim M., Hazra, Sugata, Troell, Max,Samanta, Sourav,Basu, Oindrila, Marcinko, Charlotte L.J., & Chanda, Abhra. (2022). Economic incentives drive the conversion of agriculture to aquaculture in the Indian Sundarbans: Livelihood and environmental implications of different aquaculture types. Ambio.

Giri, Sandip, Samanta, Sourav, Mondal, ParthoProtim, Basu, Oindrila, Khorat, Samiran, Chanda, Abhra, &Hazra, Sugata. (2021). A geospatial assessment of growth pattern of aquaculture in the Indian Sundarbans Biosphere Reserve. Environment, Development and Sustainability24, 4203–4225.

Samanta, Sourav, Hazra, Suagata, Mondal, Partho Protim, Chanda, Abhra, Giri, Sandip, French, Jon R., & Nicholls, Robert J. (2021). Assessment and Attribution of Mangrove Forest Changes in the Indian Sundarbans from 2000 to 2020. Remote Sensing 13(24), 4957.


Banner image: A cleared mangrove patch making way for aquafarming in the Sundarbans Biosphere Reserve. Photo by School of Oceanographic Studies, Jadavpur University

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