Reproductive Dynamics of Coryphaena hippurus (Linnaeus, 1758) Recorded from the Bay of Bengal, India

Coryphaena hippurus, one among the large pelagic species landed from Bay of Bengal, forms an important bycatch in drift gillnets and hook and lines. The present study, first from the region, is aimed at elucidating the reproductive biology from 1150 fishes from 2017 to 2019. Fork length of sampled fishes ranged from 25 cm to 110 cm and females contributed to the catch only up to a length of 88 cm. Growth was negatively allometric and length composition varied between sexes. Sex ratio was 1M:2.04F, significantly favouring females in most months, and more so in fishes measuring below 60.0 cm. Size at sexual maturity for females and males was 54.57 cm and 59.97 cm. Monthly percent contribution of spawning females and males ranged between 20.00 to 60.61 and 29.17 to 53.57. Monthly gonadosomatic index for females and males varied between 1.48 to 3.82 and 0.89 to 1.94. The values differed significantly; higher values during August to November indicated a peak in spawning. However, spawning occurred round the year, as evident by the presence of spawners and moderate values of the gonadosomatic index. Absolute fecundity ranged from 115,200 eggs to 1,501,808 eggs, with an average of 434,688 eggs. Egg size distribution demonstrated asynchronous gonadal development and batch spawning. Egg diameter of most abundant oocytes ranged from 0.60 mm to 0.69 mm, followed by another peak at 0.80 mm to 0.89 mm. Present study, first from region, provides detailed insights on reproductive biology, some of which are maiden information from Indian Ocean and knowledge generated would contribute significantly to stock management.

Automated summary

This study provides detailed insights into the reproductive biology of Coryphaena hippurus in the Bay of Bengal, including information on sex ratio, size at sexual maturity, monthly spawning contribution, gonadosomatic index, and absolute fecundity. It is the first study of its kind in the region and contributes important knowledge to the management of this species in the Indian Ocean.