Effectiveness of community-enterprise approach in promoting crop-fish culture practice in some tidal floodplain areas of Bangladesh

Abstract

Bangladesh has 2.8 million ha floodplain water bodies and these floodplains are essential for the livelihoods of most of the rural people of the country. A study was conducted to assess the impacts of community enterprise approach floodplain aquaculture practices on the local environment, its biota and local production systems in three selected tidal floodplains, namely Jhanjhania Floodplain (FP) in Pirojpur District, and Bisnudia and Uttampurpur Floodplains in Jhalakathi District, located in the southern Bangladesh. In particular, the impacts were assessed in terms of water quality, zooplankton, fish and other aquatic biodiversity, soil fertility and rice production, cropping pattern, abundance of aquatic vegetation, access rights to the floodplain resources by the local people. Field data was collected for the period of three years (2016-2019) with provision for seasonality. Initially, the study focused on the documenting the prevailing environmental quality of the floodplain under the culture practice. Later, concomitantly, data were also collected from three selected control sites, corresponding to each intervention site, with a view to compare the data collected from intervention and control sites in order to able to assess impacts. A total of 12 physico-chemical parameters, namely water pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), salinity, alkalinity, total hardness, total phosphate, total ammonia-N, nitrate-N, ammonia-N, nitrite-N and temperature was monitored quarterly. The values of observed water parameters, particularly that in wet season, represent the typical values for floodplain ecosystem in Bangladesh. There were strong seasonal fluctuations in most measured water parameters. Except pH, salinity and DO levels, in most cases, the intervention sites had higher values for measured water parameters compared to that of control sites. The zooplanktonic community of the project sites was represented by 45 species, belonging to six major groups, viz., Cladocera (9 sppecies), Copepoda (5 species), Ostracoda (3 species), Rotifera (20 species), Ostracoda (3 species). Protozoa (3 species) and others (2 species). Rotifers, copepods appeared most dominant groups, followed by cladocerans and naupli. Seasonal variations were observed in the abundance of zooplankton in all study sites. A total of 60 species of fish belonging to 26 families have been recorded from all the three study sites, of which 51 species occur naturally in the wild and 9 species are cultured in the floodplains. Of the stocked fishes, 5 species were exotic. In the studied floodplains showed a declining trend in fish abundances, which is reflective of regional decline in fish abundance. In general, the study sites were comparatively poor in molluscan fauna. In total, six species of molluscs were recorded from the study sites. Three species of crabs and five species prawn were recorded from the three study sites and all the species were common to fairly common within each site. There is no evidence on the disappearance of any fish species or the other animal species due to project intervention. As per local accounts production of indigenous species in the stocked floodplain has increased which simply reflect the absence of fishing, complete harvest of fish at the outlets, with having any fish escapes. Soil quality analysis was done only for dry season; both for intervention and control sites, and parameters investigated were organic matter, total nitrogen, phosphorous, sulphur, potassium, pH and electrical conductivity. The results indicated that soil fertility of the study sites was medium to high. The measured soil parameters were comparatively higher in intervention sites compared to control sites and probably resulted from fertilizer and feed inputs and less uptake of soil nutrients by the reduced abundance of aquatic vegetation. As revealed by Focus Group Discussion (FGD) and interview of farmers, the production of crop in Jhnjhania intervention site increased by about 25%, compared to pre-intervention period. Concomitantly, the production cost for HYV boro cultivation decreased at least by Tk. 1500-2000 per bigha as because less labour cost for removal of weeds from land and less use of pesticides in crop field, compared to pre-intervention period. There had been little changes in the cropping pattern in the study sites, except the Bishnudia site, which has been modified to perennial water body dedicated for only fish culture. While the project has many positive impacts in increasing the fish production and generating income streams for local people, however, future promotion of the initiative should address the constraints identified. The promotion of floodplain fish culture practices must not be done on a large scale in an area in order to avoid the negative consequences on river fisheries and local biodiversity. Since the floodplains are stocked with over wintered or large fingerlings, the inlets to the floodplains could be blocked with large mesh size nets, allowing the lateral migrations of small fish, juveniles even during the grow out period. In any case the inlets (connectivity with the rivers) must not be blocked /closed before the end of Ashar to facilitate lateral migration of fish, fry, etc. The provision for water inlets/outlets should be kept more and as far as possible no inlets should be permanently closed. An alternate livelihood options should be generated to the affected fishers with provision for easy and interest free access to micro-credits and facilitate their access to different welfare service providers. In each stocking floodplain an auto stocked fish pit should be preserved (unfished) to maintain a self-sustaining indigenous fish population. The modification of floodplains to a complete impoundment in the form of a closed water body (as done in Bishnudia) over a large area with complete regulated hydrology only for fish culture purpose must not been done.