Mangrove forests along the tropical coast are one of the most important and productive ecosystems in the world. It plays an important role in stabilizing the world's climate by high carbon storing capacity. They are the nursery of countless fish species that are important for inshore fishing and they also protect the coastal population from tropical cyclones by reducing their intensity. But in recent decades, these productive ecosystems have come under severe threat. Mangrove forest cover has decreased by 20 percent worldwide since 1980. One of the main factors for their destruction is the indiscriminate expansion of shrimp aquaculture - especially in the countries of South and Southeast Asia. Another problem associated with shrimp and crab aquaculture is that the demand for pathogen-free shrimp larvae and crablets cannot be met by existing hatcheries. As a result, they are illegally caught in alarming proportions in the wild in mangrove areas to fulfill the demand. Additionally, in the complex supply chain in Bangladesh, up to six middlemen are involved between farmers and processing or exporting companies, leading to economic discrimination of farmers and limiting their economic and strategic position.
Mangrove regeneration in aquaculture ponds which is called Integrated Mangrove Aquaculture (IMA) could be a good way to increase mangrove coverage in the shrimp culture areas of southwestern Bangladesh. Integrated mangrove-shrimp cultivation, also known as organic aquaculture, is an option for mangrove restoration to compensate for mangrove area lost through conventional shrimp aquaculture. Shrimp farming with the integration of mangroves is a promising mechanism to reduce blue carbon emissions. Integrated mangrove aquaculture is environment friendly shrimp farming with the incorporation, conservation and restoration of mangrove forests. It is a sustainable farming system where shrimp and other fish species are grown in natural habitat of mangroves. In IMA, mangroves are planted alongside of aquaculture farms and provides natural ecosystem to the shrimps and other fish species which improves the quality and productivity of the fishes. Organic farming system is practised in IMA to ensure the quality of the aquaculture species. IMA causes no environment pollution and excess feeds and chemicals are avoided in IMA ponds, thus it is an environment friendly approach. The production cost of shrimp farming reduces in IMA as the organic leaf litters can add natural feed sources into the pond’s water. The international market price of organic shrimp is high. Farmers can get more profit by producing and exporting the organic shrimp in IMA ponds which can improve the economic condition of the farmers as well as conserve the mangrove ecosystem.
The aim of the project is also to establish a partnership-based dialogue on topics of sustainability and mangrove protection in shrimp production and trade in the producing countries in India and Bangladesh, and Germany as a central export and consumer market on the other hand. This will be done by involving various stakeholders along the value chain - from the small farmers and the processing companies to the consumers. Integrating and further developing various existing approaches through multi-stakeholder partnerships, concrete measures will be implemented to promote environmental protection technology and policies in the sector.
The social benefit of IMA is ensured by the socio-economic development of the IMA farmers through local value creation. This improves their organizational structures by introducing innovative management models that leave a higher added value with the IMA farmers. The IMA farmers will be able to represent their products in different national fair through the cooperative society. Additional feeds and chemical application are not required in IMA ponds as the mangrove ecosystem provides natural feed for shrimp and other fish species. This reduces the production cost of shrimp and fish on the one hand and the risk of aquatic pollution on the other. Growing mangroves in IMA ponds creates a comfortable environment for fish by providing shade during extra sun and reduces the risk of shrimp and fish mortality.
IMA provides local communities with regular income from shrimp farming as well as from fishery products, while rehabilitating mangrove forests. The IMA farmers are producing shrimps organically and the value of organic product is much higher in international markets. IMA farmers will be able to sell their produce directly to the company through cooperative societies. Thus, the manipulation of the middlemen will be reduced and farmers will be able to get the desired value of their products.
In IMA, mangroves are conserved in the shrimp/ aquaculture farms. This will contribute to the conservation of diverse ecological functions of the mangrove forests on the spot. It increases mangrove area and helps maintain biodiversity as mangroves provide nursing grounds for a number of aquatic species and are home to numerous animal and bird species. The restoration of mangrove forests by practising IMA can help reduce greenhouse gas emissions as these trees are highly efficient in capturing and storing carbon. The presence of mangrove trees protects coastal regions from soil erosion and reduces their vulnerability to negative impacts of climate change and natural disasters. The presence of mangrove trees can improve the water quality of shrimp ponds, which can limit disease outbreaks because they have bio-filtering capabilities and they prevent water temperature shocks. Mangroves are also called salinity tolerant trees. These trees help reduce the concentration of salt in the soil and water in the coastal areas. The reduction of salt concentration by mangrove trees in coastal areas is called natural filtration.
Since shrimp is cultivated in a large area in the south-western region of Bangladesh, therefore, through the integrated mangrove aquaculture in these shrimp farms, it is possible to preserve the mangrove ecosystem on the one hand and financially benefit the fish farmers on the other. This is also a good way to contribute to the development of citizen science as well as the achievement of SDGs.
The writer is a Professor of Agrotechnology Discipline, Khulna University