Ovarian Maturation, Size at Sexual Maturity, and Spawning Season of Parapenaeus FissuroidesCrosnier, 1985 (Decapoda: Penaeidae)

Abstract

Reproduction, including ovarian maturation, size at sexual maturity, and spawning season of Parapenaeus fissuroides Crosnier, 1985 (Decapoda: Penaeidae), were studied using females collected from Kagoshima Bay, Kyushu, Japan. The ovaries of individuals were examined by histological observations to estimate the degree of ovarian maturation. Ovarian maturity stages were classified into four categories based on the developmental stage of the most advanced oocytes in the ovary as follows: undeveloped, developing, nearly ripe, and ripe. The mature females were defined as those having nearly ripe or ripe ovaries containing cortical granules in the peripheral region of the oocytes. The gonadosomatic index (GSI) significantly increased with progress of ovarian maturation and most of the females with GSI ⩾ 6% were mature. The size at sexual maturity of female P. fissuroides was estimated to be 23.5 mm in carapace length. The spawning season of this species was estimated to last from July to February with a peak during October and November.