Title : Mud crab fisheries management and farming opportunity in the coastal area of Bangladesh, enhancing coastal livelihood resilience amid climate change
Abstract:
Bangladesh’s coastal regions, home to nearly 29% of the population and projected to reach 57.9 million by 2050, are increasingly threatened by natural disasters such as cyclones, storm surges, and riverbank erosion. These recurring events damage infrastructure, disrupt livelihoods, and endanger vital coastal industries like fisheries and aquaculture. While shrimp farming has traditionally been the cornerstone of brackish water aquaculture, frequent disease outbreaks have highlighted the need for alternative livelihoods. Mud crab (Scylla olivacea), a species with high market value, has emerged as a promising option. However, harvesting and exportation continue to grow without adequate knowledge of crab biology, habitat requirements, or modern farming techniques.
A comprehensive three-year study (2021–2023) investigated the ecological dynamics of mud crab habitats in mangrove ecosystems. It revealed that salinity is the most critical environmental factor shaping crab distribution and reproductive behavior. High-salinity zones with low elevation and clay loam soils supported the highest crab abundance (3.02 ± 0.77 individuals/hr/gear) and plankton diversity, critical for juvenile recruitment. While male crabs dominated across all investigating areas, mature females were more prevalent in low to moderate salinity zones. These findings emphasize the importance of habitat-specific conservation, sustainable harvesting, and adaptive management to support long-term mud crab viability and biodiversity in the Sundarbans.
To explore aquaculture-based solutions, Bangladesh's first indoor vertical mud crab farming trials using a Recirculating Aquaculture System (RAS) were conducted. The trials tested crab adaptation to different salinity levels, tied versus untied conditions, and water flow types. Higher survival rates were recorded under high salinity (>15 ppt), untied conditions, and running water. In fattening trials, crabs were reared individually in vertical boxes and fed with tilapia feed, achieving 55% survival and 91.67% fattening success, excluding the initial trial. These results confirm the feasibility of vertical mud crab farming in controlled indoor systems. However, the method faces key challenges: prolonged fattening periods (over 30 days), high mortality from transport stress, and significant initial investment, mainly due to RAS infrastructure. Future efforts should explore using natural coastal water to lower operational costs and improve sustainability. With further optimization, indoor vertical farming of mud crabs can offer a resilient, high-value livelihood for coastal communities, particularly during climate-induced instability.
