The Bangladesh floodplain fisheries

摘要

During the monsoon the Bangladesh floodplain becomes integrated into a single biological productive system. A conservative estimate of the number of freshwater bony fish species present in the system is 273 of which 13 are exotics. Cyprinids, catfishes and hilsa shad Tenualosa ilisha, a clupeid, predominate. About 20-30 fishes, mostly blackfishes, which are resident in the floodplain and tolerant of low levels of oxygen provide the majority of the national freshwater fish production. Most of the rural population fish professionally, seasonally or for subsistence. In addition to the harvesters, a further two million people are involved in activities related to the fisheries sector. The yield in the floodplain may vary from 50 to 400 kg ha(-1) per year and the majority of the fishes is eaten fresh. For full-time fishers, conflict over water resources can be intense during the dry season when water is required for irrigation. Flood control, drainage and irrigation schemes may obstruct the lateral migrations of rheophilic whitefish species and the passive drift of larvae from the main channel to the modified floodplains. Existing modifications to the hydrological regimes may cause reductions in catch per unit area and fish biodiversity. The area under flood control is expected to be 5.74 x 10(6) ha in 2010 resulting in a loss of ca. 151,300 t of fishes. There has been a move away from the leasing of water estates ('jalmohals') to the promotion of co-management. The open access policy, which has led to severe competition for the resources, has reduced the effectiveness of co-management. The future aim is to shift the benefits to the fishers and to ensure the long-term sustainability of the resources. Both habitat restoration and fish enhancement are important in sustaining the floodplain fisheries