Reproductive traits in dolphinfish Coryphaena hippurus Linnaeus, 1758 along the coastal waters of Karnataka, south-eastern Arabian Sea

Abstract

The maturity, sex ratio, gonadosomatic index (GSI) and fecundity of Coryphaena hippurus was investigated from 347 specimens collected along Karnataka coast, south-eastern Arabian Sea from August 2017 to May 2018. Overall sex ratio of 1:3.5 (male:female) indicated dominance of females in the fishery and differed significantly (p<0.05) in all the months, except in January, May and December. The fork length (FL) at 50% maturity (Lm₅₀) was estimated at 47.5 cm for both males and females. The pattern of GSI and maturity stages suggests peak spawning activity in August-September. However, the incidence of fishes capable spawning all through the year in varied proportions implied that spawning activity occurs throughout the year. The absolute fecundity estimates varied from 1,00,298 eggs for a female of 53.5 cm FL to 6,15,267 eggs for female of 113 cm FL with an average fecundity of 3,18,446 eggs per female. Thefecundity of fish increased with body length and weight as well as with gonad weight. The biological information on maturation, reproductive cycle, spawning periodicity and fecundity of C. hippurus in the tropical Arabian Sea could be useful for developing appropriate management tools and conservation strategies for this commercially important fish species.

Keywords: Fecundity, Gonadosomatic index, Mahi mahi, Sex ratio, Size at first maturity