Effect of different species combinations of finfish with black tiger shrimp (Penaeus monodon) on production performance, economic efficiency and water productivity in extensive brackishwater polyculture system

摘要

We examined species compatibility, production performance, water productivity, water use efficiency and profitability aspects of shrimp-fish polyculture to promote livelihood options for resource-poor coastal farmers. Four species were evaluated in this polyculture system. Initial weight ofP. monodon, M. cephalus, C. chanos and L. parsiaat the time of stocking was 0.02 +/- 0.01, 3.29 +/- 1.81, 7.29 +/- 1.41 and 0.39 +/- 0.08 g, respectively. Stocking density of each finfish was 0.5 m(-2)while that of shrimp was 2.0 m(-2). During 240-day experimental trial, growth performance ofP. monodonwas 42.65 +/- 1.25, 35.54 +/- 1.95, 31.63 +/- 1.42 and 44.17 +/- 1.53 g, respectively in T-1(P. monodon, M. cephalus and L. parsia), T-2(P. monodon,L. parsiaandC. chanos), T-3(P. monodon,M. cephalusandC. chanos) and T-4(P. monodon, M. cephalus, C. chanos and L. parsia) and differed significantly (p < .05) among treatments. Among fishes, higher (p < .05) mean body weight ofM. cephalus(487.17 +/- 20.42 g) andL. parsia(54.16 +/- 6.3 g) was recorded in T-1, while that ofC. chanos(382.91 +/- 18.39 g) in T-2. Species-wise biomass contribution (kg/ha) ofP. monodon(352.72 +/- 11.4), M. cephalus(1235.07 +/- 20.4),and L. parsia(151.63 +/- 7.4) was significantly higher (p < .05) in T-1, while that ofC. chanos(621.49 +/- 19.3) in T-3. Although higher productivity was recorded in T-4(1931.64 kg/ha), species-wise higher growth performance (p < .05) of all species in T(1)was indicative of species compatibility. Higher net total water productivity (INR 8.83-17.62 m(-3)), water use efficiency (91.6-102.3 g biomass m(-3)) and benefit-cost ratio (1.82-2.79) in all the treatments except T(2)were an indicative of efficient water use and economic viability of polyculture system. However, keeping in view the growth performance, species compatibility, benefit-cost ratio and consumer preference, T(1)was found to be the most promising. Since the growth rate at early life stage is slow, stocking advanced fish fingerlings in polyculture system is advisable for higher survival rate, productivity and profitability.