Biological study of reproductive characteristics of Acanthopagrus schlegeli in Daya Bay

We collected 721 individuals of Acanthopagrus schlegeli in Daya Bay in January, March, April, August−December, 2018, and then investigated the annual variation of reproductive characteristics of A. schlegeli in Daya Bay so as to provide a theoretical basis for its artificial breeding and conservation. The results show that: 1) the spawning period falls between November and March. The total length ranged 175−487 mm for females averge (297.92±56.61) mm. The body mass ranged 90.96−1 907.12 g for females average (511.36±307.53) g. The total length ranged 110−440 mm for males average (237.61±61.05) mm. The body mass ranged 21.92−1 370.00 g for males average (277.76±210.33) g. The full lengths of females were significantly longer than those of males (P<0.001). 2) The gonad maturity coefficient and gonad development indicate that the reproductive period of A. schlegeli in Daya Bay was from November to March. 3) The existence of androgynous individuals indicates that the species will undergo sexual reversal, and the males will mature first and then change to females. 4) The total lengths (TL) at 50% sex maturity for females and males were 248.52 mm and 148.03 mm, respectively. 5) A. schlegeli is a multiple spawner with indeterminate fecundity by oocyte size-frequency distributions. The number of the individual fertility ranged from 84 100 to 2 655 168 granules (average 728 732±499 547). The relative fertility of total length was 380.54−8 271.55 eggs·mm⁻¹ (2 731.44±1 630.93) egg·mm⁻¹. The relative fertility of body mass was 277.58−3 592.83 eggs·g⁻¹ average (1 443.87±766.82) eggs·g⁻¹. There was a linear correlation among absolute fecundity and total length, body mass and gonadal mass.