Induced maturation in ablated Penaeus notialis and Penaeus schmitti

Abstract

Wild Penaeus notialis and P. schmitti were induced to mature by unilateral eyestalk ablation of females in 0.5, 1.6 and 2.0-m super(3) tanks stocked at 9-12 shrimps/m super(3). A total of 71 spawns was obtained from 80 P. notialis) females in 2 experiments and 29 spawns from 72 P. schmitti females in 3 experiments over 16-19 days per experiment. Average fecundity and hatch rate were 44,410-64,997 eggs/spawn and 0-71.70% for P. notialis and 41,672-48,083 eggs/spawn and 0-0.17% for P. schmitti , respectively. The low hatch rates throughout the experiment period for P. schmitti , an open thelycum species, and towards the second week for the closed thelycum P. notialis , indicate a failure of spermatophore transfer in the maturation tanks. This lack of copulation may be traced to the high stocking densities and the small sizes of the tanks. Attempts to artificially transfer spermatophores to mature P. schmitti females were generally unsuccessful.