Feasibility of rice-crab (Scylla olivacea) co-cultures in the south-west coastal ghers of Bangladesh

Abstract

To assess the production performance in terms of growth, survival and intactness of mud crab in co-culture with rice plants an experiment was conducted for a period of 120 days in the ghers of two villages under Paikgacha Upazilla, Khulna. The crab juvenile was collected from adjacent Shibsha River and stocked in two experimental ghers of 0.004 ha area each without considering male female ratio. The stocking density was 50 per decimal, 75 per decimal, 100 per decimal in T₁, T₂ and T₃ treatments of two experiments, respectively. Fresh chopped tilapia fish was fed to the crab and the requirement of supplied tilapia fish was adjusted periodically in accordance with the growth performance or body weight of crab. Production and physico-chemical parameters were recorded and analyzed according to standard methods. Among these parameters salinity had significant (p<0.05) role on survival of mud crab. After 120 days of rearing we obtained average final weight of cultured crab (Scylla olivacea) was 154.6±12.19g, 135.46±21.30g and 107.23±14.87g; with the estimated yield of 995.96±193.43 kg/ha, 1179.4±266.68 kg/ha and 1144.22±544.05 kg/ha, survival was 45%, 47% and 42% in T₁, T₂ and T₃ treatments respectively in Bayra village; On the other experimental site in Gopalpur village  we obtained average final weight of cultured crab was 169.2±19.20g, 155.22±17.73g and 167.53±18.60g; with the estimated yield of 476.83±160.51 kg/ha, 793.73±361 kg/ha and 1636.19±868.32 kg/ha, survival was 25%, 27% and 22% in T₁, T₂ and T₃ treatments respectively The yield of rice was found 6006±1021 kg/ha, 6026±991 kg/ha, 5995±1005 kg/ha in T₁,T₂,T₃ treatments respectively in the experiment of Bayra village on the other  hands in Gopalpur village the yield was 5877±1297 kg/ha, 5743±1350 kg/ ha, 5468±1190 kg/ha in T₁,T₂,T₃ treatments respectively. Results and findings of the present study suggested that yield of rice was not hampered for rice-crab co-culture in ghers. According to the experimental results poor salinity level, temperature, water level fluctuation and winter seasons are the potential constraints in the growth, survival and intactness of rice crab co-culture in the coastal ghers of Bangladesh.