Sustainable Mangrove Fishery

The Problem

The Sundarbans, the single largest mangrove patch in the world was about three times larger until the 1770s. These mangroves were cleared at different times over the centuries, initially for agriculture and settlement, and more recently for aquaculture. Over the last two decades, on the Indian side of the ecoregion, there has been a steady growth in aquaculture, especially in the north-eastern part. Aquaculture farms now cover approximately 50,000 hectares of the region.

Recent studies suggest that aquafarms have grown at the cost of agricultural land (more than 20,000 ha), mangroves and mudflats (more than 1,700 ha in the last two decades). Despite its economic benefits, shrimp farming has been under scrutiny globally because of its environmental and social impacts. Apart from the loss and degradation of mangroves, aquafarms raise the salinity of adjacent agricultural farms, reducing productivity. Presently, the aquafarms are devoid of vegetation. The social impacts include land alienation and loss of occupation.

A Potential Solution

To bring back vegetation in its historical distribution area, WWF-India is establishing a model of sustainable mangrove fishery as part of Nature-based Solutions (NbS). This intervention, builds on existing models of Integrated Mangrove Aquaculture (IMA) and Sustainable Mangrove Fisheries (SMF).

Regeneration of mangroves in aquafarms not only provide shade and nutrition through the decomposition of mangrove leaves to shrimps, but also improves health of shrimps by tapping into the natural antimicrobial potential of resident microbiome of aquaculture ponds. Carbon sequestration is increased manifold by the mangrove vegetation.

To implement the solution, a partnership with a pioneering organic aquaculture company, Blue Sea Aquaculture Private Limited, was initiated. In consultation with local stakeholders, 5 hectares of aquafarms were identified across one revenue village in Haroa block, North 24 Parganas district. In the demonstration model, 37 aquafarmers are participating.

For planting mangroves, dykes of aquafarms were modified. Mangrove species selection is based on the salinity and soil profile. Erecting bamboo fences to protect the plants from free-roaming livestock is a prerequisite.

With aim of facilitating development of carbon and biodiversity credits, a monitoring protocol has been developed. Workshops will be conducted with carbon and/or biodiversity credit traders for uptake of the model.

The Impact

Re-establishing mangroves into the aquafarms devoid of vegetation will increase shade and nutrition for shrimps, and reduce disease incidence. No use of artificial fish feeds and a disease-free yield may lead to higher economic returns. The participating aquafarmers can also claim carbon and biodiversity credits in the future.