Comparative Study on Seed Production in Two Strains of the Nile tilapia Oreochromis niloticus L.

This experiment was conducted to compare the spawning performance of the non-improved Nile tilapia Oreochromis niloticus (Chiclidae) strain (NS) with the Genetically Improved Strain of the Nile tilapia (GIFT) for 120 days. Three 0.43-m^3 breeding tanks in a recycling water system were assigned for each strain and fish were stocked at 4-breeders/tank with a male to female ratio of 1:3. Water temperature was maintained at 29.0 ± 1.0oC and seeds were harvested biweekly. Results showed no significant difference between the NS and GIFT strains in the total seed production tank^-1 (3705 and 3030 seeds, respectively), relative fecundity (31.3 and 27.5 seeds kg female^-1 day^-1, and 10.1 and 8.0 seeds female^-1 day^-1 , respectively), and system productivity (30.9 and 24.0 seeds m^-2 day^-1, respectively). No significant difference was observed in the spawning rate, inter-spawning intervals, spawning periodicity, seed composition and spawning synchrony between the two strains. Results indicated that under these experimental conditions, the spawning performance of the GIFT strain was not significantly affected by selective breeding for growth and only a slight decrease in fecundity would be expected in this improved strain.