Density and water exchange-dependent growth and survival of Litopenaeus setiferus postlarvae

Abstract

P < 0.03. According to this equation the optimum shrimp density-water exchange combination was between 5 to 12% of water exchange at stocking density of between 50 and 150 shrimp/m2. Salinity, ammonia-N and nitrite-N increased according to the time spent in tanks without water exchange. With no (0%) water exchange, water quality parameters measured were outside the optimum for L. setiferus postlarvae, The use of optimum density and water exchange in a nursery system for L. setiferus with optimum variables established is proposed.

This present study was designed to investigate the effects of stocking density and water exchange on the growth rate, survival and performance index of L. setiferus postlarvae under controlled laboratory conditions. The experiment was done with postlarvae (PL10 to PL40) at densities of 50, 150, 250 and 350 shrimp/m(2) and various different water exchanges rate per day (0, 6, 12 and 18%). The maximum growth rate was obtained for shrimp with 12% water exchange per day at all densities. A reduction of the maximum growth rate was observed in relation to density with the highest values in shrimp stocked in a density of 50 and 150 shrimp/m(2) (mean value of 0.53 mg/d) and the lowest in shrimp stocked in a density of 350 shrimp/m(2) (0.24 mg/d), The multiple regression equation obtained to relate performance index (growth rate survival : PI), shrimp density (X-1) and water exchange (X-2) was: PI = 0.31 + (0.001) X-1 + 0.039 X-2 + 2.28 x 10(-6) X-1(2) + (-0,0017) X-2(2) + (0.000026)X1X2,R-2 = 0.78