This study investigated the feasibility of artificial propagation of the giant grouper Epinephelus lanceolatus. Experiments with HCG and LHRH-a injection were conducted to observe the spawning behavior, embryonic development and hatching. The results are summarized as follows:
Spawning season extended from May to October.
Dosages of 390-400 IU／kg HCG and 41-42g／kg LHRH-a body weight
were used for injection during the early spawning season in May and June, and 350 IU／kg HCG and 38 g／kg LHRH-a body weight in the mid spawning season.
Ovulation occurred about 48 h after injection and once per month. After injection, males jumped as part of chasing the females. The chasing behaviour lasted for six hours. The fertilized eggs were pelagic, spherical, and transparent. They ranged 0.80-0.89 mm in diameter, and each had an oil droplet of 0.18-0.19 mm in diameter. The fertilization rate was 80%. Incubation period was approximately 19 h 36 min at the water temperature of 28-29℃. The newly hatched larva was 1.65 mm in length. Hatching rate of fertilized eggs and survival rate of newly hatched larvae varied significantly with salinities. Hatching rate was highest (90%) at 30 ppt, but hatching failed at salinities ranging from 0 to 5 ppt. The survival rate of newly hatched larvae was highest (84%) at 30 ppt. Newly hatched larvae did not survive at the salinities lower than 20 ppt.
Key words: Epinephelus lanceolatus, Artificial propagation, Embryonic development