A preliminary study on reproduction and feeding habits of Lutjanus gibbus from Meiji Reef of Nansha

Lutjanus gibbus, a kind of coral reef fish with delicious meat and high economic value, whose spawning aggregation can easily lead to overfishing. Based on 67 individuals of L. gibbus collected by diving fishing in the waters of Meiji Reef in July 2020, we investigated its basic biological characteristics, including sex ratio, sexual maturity body length, egg diameter characteristics, fecundity and feeding habits, in order to provide basic biological data for the protection and management of L. gibbus. The results show that the ratio of female to male of L. gibbus was 2:1; the 50% sexually mature body lengths of males and females were 204.757 and 201.623 mm, respectively; the egg diameter of Stage IV gonadal was 0.176–0.419 mm with an average of 0.296 mm; the frequency distribution of egg diameter was unimodal. The fecundity of L. gibbus was 51 858–276 205 eggs with an average of 139 145 eggs. Its fecundity had a significant power function relationship with body length and body mass. The preys of L. gibbus from Meiji Reef were crabs, fish, snails, shellfish and shrimps. The stable isotope study shows that the average trophic level of L. gibbus was 3.33, and its feeding habits changed significantly with individual development (The niche width was narrower and the trophic level was higher).