Development and Deterioration of Spermatophores in Pond-Reared Penaeus vannamei

Spermatophore deterioration in pond-reared Penaeus vannamei was studied, and spermatophore quality was evaluated and improved. Sperm production of males collected from grow-out ponds was increased by two techniques: eyestalk ablation using a fresh frozen maturation diet (13% body weight); and laboratory culture using a diet of the formulated feed Nicovita Plus (3% body weight/ d) and frozen squid (2%). Findings are complementary to previous reports that eyestalk ablation improves quality of spermatophores in young (25.7 g) males. The timing of eyestalk ablation for activation of the endocrine mechanism, leading to improved spermatophore quality was also explored. After eyestalk ablation, performed between postmolt and intermolt stages, 26 g males required a minimum of three spermatophore regenerations or 42 d to significantly increase spermatophore size and sperm count. On the other hand, the laboratory culture (2.5 mo) technique improved the quality of spermatophores in successive regenerations for non-ablated males. In the present study, subadult P. vannamei produced spermatophores which, if not transferred or manually ejaculated, gradually deteriorated (successive stages are described), while a new compound spermatophore was being synthesized.