Insights into the reproductive biology of the common dolphinfish Coryphaena hippurus Linnaeus, 1758 (Coryphaenidae), in Indian seas

Understanding the reproductive biology of a species aids in formulating conservation strategies and in developing sustainable culture practices. The common dolphinfish, Coryphaena hippurus Linnaeus, 1758, is caught all along the Indian coast in different gears such as gillnets, hooks and lines and trawl nets. This study was undertaken to examine the reproductive behaviour of the species focusing on peak spawning season, fecundity and size at first maturity. The study was based on a total of 1973 individuals collected from seven landing centers across the country. Length of females ranged from 25 to 103.5 cm TL with a mean of 74.74 cm TL, while males ranged from 31.7 to 123.5 cm TL with a mean of 74.01 cm TL. Females predominated across all months and size groups, with an average annual sex ratio of 1.9:1 (Female:Male). The estimated size at first sexual maturity (Lm50) was 62.6 cm TL for females and 65.9 cm TL for males. Absolute fecundity was estimated at 402,085 eggs per female and relative fecundity at 185 eggs (SD ± 85) per gram weight of female. Mature adults were observed year-round, with peak gonadosomatic index (GSI) values in August, September and January. Ova diameter study showed asynchronous spawning in the species. The results of this study provide valuable inputs for developing a species-specific fishery management plan for common dolphinfish in Indian waters. Keywords: Asynchronous spawning, Fecundity, Gonadosomatic index, Indian fisheries, Pelagic fish, Sex ratio, Spawning