World Aquaculture September 2018

46 SEP TEMBER 2018 • WORLD AQUACULTURE • WWW.WA S.ORG riphyton on crab boxes, thereby serving to clean boxes biologically and reducing farming costs. In crab fattening systems, tilapia, mullet, milkfish and pearlspot are among the most compatible fish species for polyculture (Sathiadhas and Najmudeen 2004). In Bangladesh, research efforts are needed for species selection and the development of culture techniques under crab cages. Challenges to Soft-shell Crab Production in Bangladesh Mud-crab aquaculture remains in its infancy (Paterson andMann 2011, Azra and Ikhwanuddin 2015). Soft-shell crab farming is a recent commercial aquaculture activity in coastal Bangladesh and operates at a very low scale compared to the heavy market demand. Some of the shortcomings/limitations on this type of business include: Lack of infrastructure. The primary sites for producing soft- shell crabs are in close proximity to the Bay of Bengal, within comparatively disadvantaged coastal sub-districts. Natural disasters have had a significant negative impact on transportation and communication systems in this area. An irregular electricity supply requires farmers to use backup generators, increasing the cost of farming soft-shell crabs. Problems with access to information (limited telephone and internet access) and poor contact with buyers and other business connections result from insufficient coverage by cellular telephone networks. The poor availability and high price of production materials are barriers for the smooth functioning of soft- shell crab production. Many farms lack access to good-quality saline water for farming and fresh water for cleaning crabs and human use. Regulatory policies also make it difficult to obtain required permits for establishing farms and exporting products. Lack of technical knowledge. The production technique for soft-shell crabs can be challenging. The process of obtaining soft crabs has a very technical focus and requires skill and considerable patience. Many biological and environmental factors are involved in molting and maintaining optimal environmental and nutritional conditions during the process contributes to greater production. Poor quality of stocked crabs and pond water conditions can delay molting. Additionally, the ability to critically observe and monitor molting status during premolt stages to forecast the timing of molting and to enable immediate harvest of newly molted crabs can directly influence production rates of soft-shell crabs (Ostrensky et al. 2015). Poor knowledge of crab fatteners about farming was documented in previous studies (Ferdoushi and Xiang-Guo 2013, Amutha 2016). Limited supply of seeds andhighprice of inputs. The daily demand for juvenile crabs for stocking is a critically important issue for this sector. As a result of the gradual expansion of soft-shell crab farms and increases in the capacity of existing production units, the requirement for seed has grown substantially. Additionally, irrespective of sizes collected for soft-shell crab farming, there is a sharp demand for the same inputs as the traditional production and marketing of hard-shell crabs, most of which are exported live. The intensive collection of juvenile mud crabs has had a negative impact on the status of wild populations. Secondly, the augmented demand for trash fish as crab feed is also generating environmental pressures in coastal areas. The price of these inputs is generally rising and at times supplies are unpredictable. These factors have contributed to a lack of business security and in some cases the failure of small-scale producers. For these reasons, a steady supply of seed is indispensable for the strength and sustainability of this emerging sector (Quinitio et al. 2015). Lack ofmarketing access for small-scale farmers. In Bangladesh, access to export markets for soft-shell crabs is limited. External buyers of soft-shell crabs prefer larger-scale suppliers, favoring bulk purchases and shipments. Consequently, small-scale producers of soft-shell crabs sell their production to larger-scale producers with processing facilities and shipment capacity. These pooled supplies are then exported in the absence of market competitors, in a somewhat monopolized business environment. For these reasons, smaller operators and investors in soft-shell crab production may be restricted to marginal profit levels. Quality assurance andquality control. The maintenance of prop- er product quality of soft-shell crabs for export is crucial. Many soft- shell farms have facilities for freezing and storage but smaller farms send their products to nearby processing plants that can compromise product quality during handling and transportation (Fig. 9). Internationalmarket competition. Commercial exploitation and marketing systems for crabs in Bangladesh are entirely export based, with limited demand in domestic markets (Chandra et al. 2012, Ferdoushi and Xiang-Guo 2013). Requirements for development of adequate and equitable connections with international export and domestic markets present significant challenges for the Bangladesh crab sector. Apart from these, other crab-producing countries may have competitive advantages with the advancement of technological innovation in the production and processing of value-added products to meet consumer preferences. Conclusion Recent increases in the production of cultured mud crabs, accompanied by advancing technology and encouraging prospects in coastal Bangladesh, suggest that the mud crab industry will continue to develop in that area. Economic and market incentives are strong and soft-shell crab production has compelling potential in terms of profitability and sustainability. The future of the soft-shell crab industry hinges largely on the continued development of reliable sources of juveniles. Improved hatchery methods are the subject of a focused effort in Bangladesh and elsewhere. Hatchery technology, coupled with more effective conservation management of wild stocks, should contribute to the emergence of an economically and environmentally sound industry. As availability of crablets increases, FIGURE 9. Soft-shell crabs from small farms ready for transport to a processing plant in Shyamnagor, Satkhira (Photo: Md. Mojibar Rahman).