Induction of maturity and spontaneous spawning of captive broodstock of Bhetki, Lates calcarifer (Bloch) through hormonal manipulation.

Abstract

Central lnstitute of Brackishwater Aquaculture (CIBA), Chennai for the first time in India, has succeeded in the development of seed production technology for the priority candidate species sea bass (Lates calcarifer). Captive land based broodstock.of Lates calcarifer has been succes~fully developed. Broodstock of sea bass held in 100 tonne capacity RCC tanks with proper water, health and feed management strategies could be made to attain gravid condition through LHRH-a hormone treatment. Female fishes weighing 6-1 Okg size were implanted with LHRH-a hormone pellet intramuscularly. Fishes with average ova diameter d 346~-391 p were implanted with hormone pellet @ 1 0OPg/kg body weight to accelerate the maturation. Within 45 days of implantation fishes attained gravid condition with mean ova diameter of more than 450p suitable for induction of spawning. However, fishes without hormone implantation with initial mean ova diameter of 354p and 355p attained maturity only after 80 and 109 days respectively showing the importance of hormone manipulation to accelerate and advance the maturity stages. These fishes were induced to spawn through LHRH-a hormone injection @ 60-70pglkg body weight for females and 30-35pg/kg body weight for males. Spawning was spontaneous after 32-35 h of injection. Fertilization rate was from 40 to 80% with hatching rate between 25-90%. The details are discussed.