Reproductive biology of the Crimson jobfish Pristipomoides filamentosus (Valenciennes, 1830) landed along the southern coast of Kerala, India

The crimson jobfish Pristipomoides filamentosus is an important food fish belonging to the family Lutjanidae, distributed widely throughout the Indo-Pacific region, with high consumer demand and potential as a candidate species for farming. Reproductive biology of P. filamentosus was studied from 594 specimens (317 females and 277 males) collected from Vizhinjam fish landing centre on the south-west coast of India during October 2022-March 2023. The fork length (FL) of the fish ranged from 19.1 to 75.1 cm in females and 19.7 to 76.5 cm in males and the body weight (BW) ranged from 103.5 to 4276.5 g in females and 130.1 to 4346.1 g in males. The sex ratio (male: female) was 1:1.1, reflecting a marginal dominance of females in most of the months and size ranges. For females, the mean length at first maturity (Lm50) was estimated at 36.6 cm FL and for males, 35.5 cm FL. GSI showed maximum values for both females (1.73) and males (2.52) in January and February, respectively. Spawning-capable females and males were dominant during February (62.2%) and January (59.4%). Asynchronous ovarian development demonstrated multiple spawning with two distinct modes (375-404 m and 465-494 m) in the oocyte diameter distribution. Fecundity increased with fork length, body weight and ovary weight, which ranged from 151,573 to 724,856 eggs, with an average of 432,983 eggs. Based on the analyses of maturity phases and histological studies, immature, developing, spawning capable, regressing, and regenerating maturity phases for both sexes are described. Globally, information on the reproductive biology of P. filamentosus is meagre. Results of the present study could contribute to broodstock development and effective management of its fisheryin the region. Keywords: Batch spawner, Broodstock development, Fecundity, Gonadosomatic index, Histology, Length at first maturity, Sex ratio