Mangrove forests have long been recognised for their diverse set of ecosystem services including carbon sequestration, biodiversity and protection from tropical storms and tidal surges.
But in the river deltas of southern Bangladesh, where rising sea levels have forced farmers to abandon their rice crops in droves, this recognition is not as pertinent.
Instead shrimp farms – which are endorsed by the Bangladeshi government and a host of development organizations including The World Bank – have taken precedence.
“This shouldn’t be surprising” says Maksudur Rahman, conservationist and founder of the Bangladesh Environment and Development Society (BEDS). “For many who reside near the coast, the aquaculture industry is their only source of income.”
The Food and Agriculture Organization of the United Nations (FAO) estimate that about 4.5 million tonnes of farmed marine shrimp entered the international trade in 2019 – that’s more than the amount caught by fishing. Notably, in China, shrimp exports increased by over 180% in that year alone.
Except this growing market for farmed shrimp comes with a significant ecological trade-off: mangroves are often felled for shrimp ponds.
The Challenge
The construction of ponds, embankments, and other farming infrastructures in lieu of mangrove habitats can lead to coastal erosion and unwanted interference with hydrology.
These practices require significant inputs of feed to ponds in order to boost shrimp production. However, a considerable portion of this feed enters the water as metabolic waste, subsequently causing water pollution, which in turn leads to shrimp disease. Shrimp, lacking in antigens and antibodies, are easily affected by disease.
Inadequate management practices and improper pond construction hinder complete drainage, exacerbating the problem. Additionally, the continuous impoundment of water poses a threat to the survival of mangrove trees. As a consequence, many previously thriving ponds have been left abandoned or devoid of life.
The abandonment of ponds has emerged as a pressing issue, intensifying the hardships faced by local communities. Shrimp aquaculture heavily relies on shared resources such as mangroves and water, which have traditionally served as vital economic assets for marginalized households.
As a result, shrimp farmers and agriculturalists have experienced displacement and marginalization, leading to socio-economic challenges within these communities.
The Solution
Recognizing the ecological trade-offs and socio-economic challenges posed by conventional shrimp farming practices, a promising solution has emerged – integrated shrimp-mangrove aquaculture. This approach seeks to harmonize shrimp production with the preservation and restoration of mangrove ecosystems, offering a more sustainable and resilient alternative.
One of the key principles of integrated shrimp-mangrove aquaculture is the use of mangrove areas as a natural filtration system. Mangroves, with their intricate root systems, act as natural purifiers, enhancing water quality by filtering out pollutants and excess nutrients. This helps to mitigate water pollution issues commonly associated with traditional shrimp farming practices.
In this integrated system, carefully designed shrimp ponds are constructed within or adjacent to mangrove areas, allowing for a mutually beneficial relationship. The mangroves provide a protective buffer against erosion, tidal surges, and storms, reducing the vulnerability of the shrimp ponds to adverse environmental conditions. Additionally, the mangrove ecosystem provides a natural food source for shrimp, reducing the reliance on external feed inputs.
Another crucial aspect of integrated shrimp-mangrove aquaculture is the restoration and conservation of mangrove forests. Efforts are made to rehabilitate degraded mangrove areas by replanting native mangrove species. This not only helps to recover lost habitats but also enhances the overall resilience and biodiversity of the ecosystem.
Integrated shrimp-mangrove aquaculture also promotes sustainable land and water management practices. Proper infrastructure is designed to allow controlled water exchange between the shrimp ponds and the surrounding mangrove areas, ensuring a harmonious balance between the needs of both systems. This includes optimizing pond drainage systems to prevent stagnant water and minimizing the risk of disease outbreaks.
The benefits of integrated shrimp-mangrove aquaculture extend beyond ecological considerations. This approach offers opportunities for local communities, particularly those residing in coastal areas, to diversify their livelihoods.
“It’s important we work with the local people, including shrimp farmers, to develop their capacities to minimize erosion and salinisation.”
Rahman adds “If we creative incentives for proper waste treatment and biofiltration, we will have made progress on finding harmony between people and nature. That is our goal”.
Certification may also be one way forward for maintaining ecosystem health and food safety in aquaculture products.
In 2015, 95% of Belize’s shrimp production was certified under the Aquaculture Stewardship Council (ASC).
By implementing standards for water quality management and adopting practices for effluent retention and treatment, the adverse effects of effluents can be mitigated. It establishes a stable and consistent source of employment for the local community, offering economic security and livelihood opportunities.
For women, this approach increases the prospects for them to actively participate in various aspects of the integrated system, fostering gender equality and empowerment.
It’s important, however, that we don’t rely exclusively on certifications. The occurrence of unusual shrimp mortalities in Belize in the same year, later identified as Vibrio parahaemolyticus-related EMS (early mortality syndrome), serves as a reminder of the need for continuous monitoring and improvement in aquaculture practices.
Integrated shrimp-mangrove aquaculture will require various efforts to address the challenges posed by the transition from conventional farming practices. It necessitates ongoing research, stakeholder collaboration, and community engagement to develop and implement sustainable strategies that ensure the coexistence of thriving shrimp farms and healthy mangrove ecosystems.
Dare’s Approach
Dare is committed to supporting nature-based solutions that improve both environmental health and the overall livelihoods of communities most affected by climate change.
In partnership with BEDS (Bangladesh Environment and Development Society), we are dedicated to securing a sustainable future for the region.
