Mangrove forest conservation vs shrimp production: Uncovering a sustainable co-management model and policy solution for mangrove greenbelt development in coastal Bangladesh.

Abstract

Mangrove forests are remarkably diverse and productive ecosystems, with distinctive biophysical environments in intertidal coastal regions of the tropics and subtropics. In these regions, shrimp cultivation is identified as a profitable business and one of the main reasons for clearing of mangroves to construct shrimp farms. Against this backdrop and based on the first author's previous PhD research and other relevant scholarly works, in this commentary we discuss the aspects and contexts of the mangrove-based integrated shrimp farming system. Then, we recommend a model of co-management and a set of policy option towards sustainable silvo-aquaculture to protect/restore the mangrove forests and sustain shrimp production in coastal areas of Bangladesh. Mangroves and shrimp culture are not necessarily incompatible. Many mangrove species have been identified as beneficial for shrimp culture for a number of possible reasons. Most importantly, the nutrients in the leaf litter of several mangrove species have been found to enhance natural food production for shrimp. Besides the nutrient input, the leaf litter also provides surface area for biofilm development, on which different life stages of shrimp can graze. In addition, the combination of mangrove leaf litter and feed has been shown to enhance shrimp production synergistically. Additional economic benefits from mangrove-shrimp co-management include the production of timber (e.g. buildings, boats and fuel woods) and non-timber products (e.g. fruits, honey, fibers, firewood, resins and bark). Thus, mangrove-based aquaculture or silvo-aquaculture system can be considered as a nature-based solution to sustainably revitalize the economy in coastal areas where shrimp has been the economic mainstay. Though there are positive effects, we point out some potential negative impacts of mangrove-based shrimp culture, like the anti-nutrients content in the leaf litter, which might impact shrimp production. In addition, the long term use of mangrove leaf litter might degrade the water quality. Therefore, the co-management policy recommends a controlled practice of mangroves in shrimp culture to balance conservation of mangrove-based ecology and profitable shrimp production. The approach promotes nature-based solutions and fosters sustainable pathways for food production, considering socio-economic and environmental dynamics.