Biological characteristics of Epinephelus merra of coral reef waters in South China Sea

Epinephelus merra is a representative species of coral reef fishes in the South China Sea. Based on E. merra samples collected from the coral reef waters of Nansha and Zhongxisha Islands during 2018 and 2019, we investigated its biological characteristics such as age and growth, body length and body mass, sex ratio, sex gonad maturity, feeding intensity and fatness, in order to gain an in-depth understanding of the growth pattern and population characteristics of E. merra in the coral reef waters of the South China Sea. The results show that the dominant body length of E. merra in Nansha Islands was 80−160 mm; the allometric growth factor (b value) of the relationship of body length and body mass was 2.783 5; the average of fatness was 2.24; the estimated parameters of the von Bertalanffy growth equation were L_∞=183 mm, k=0.260 and t₀= −1.268. The dominant body length of E. merra in Zhongxisha Islands was 110–160 mm; the b value of relationship of body length and body mass was 2.592 5; the average of fatness was 2.02; the estimated parameters of the von Bertalanffy growth equation were L_∞=260 mm, k=0.128 and t₀= −2.494. The age of 61 individuals in Nansha and Zhongxisha Islands ranged from 1 to 6 years old, and the dominant age group was 1–2 years old. The gonad maturities of the two sea areas were mainly at Stage II, while the feeding grade was mainly at Stage I. Compared with the Zhongxisha Islands, the E. merra stock in the Nansha Islands had smaller size and faster growth rate.