Reproductive biology of estuarine migrants Mugil cephalus from Narmada estuary, west coast of India

Abstract

The reproductive biology of an estuarine migrant, Mugil cephalus, as well as the estimated length-weight relationships of the specimens obtained from the west coast of India, downstream of the Narmada estuary, were examined in the present study. From November 2018 to February 2020, gill nets, bagnets, and dragnets were used seasonally to collect fish samples from the four landing sites of Jhanor, Bharuch, Bhadbhut, and Mehegam. The studies also looked at how salinity, total alkalinity, pH, specific conductivity, depth, water temperature, transparency, dissolved oxygen, and pH affected M. cephalus reproduction. Mugil cephalus had a size range of 113–296 mm and weighed 13.2–283 g, and there were no noticeable differences between the sexes (0.97: 1.0). Males were estimated to be 158 mm in length and females were estimated to be 171 mm in length at first maturity. Throughout the seasons’, spawning activity has been seen, with a peak in winter months (January and February). The spawning season, which occurs in the months of January and February, was when highly gonado-somatic (GSI) values were observed. Mugil cephalus was found to be a high-fecund species, with absolute fecundity, ranging from 18525–567688 (184706 ± 159527, mean ± SD) and relative fecundity from 207–2117 (1012 ± 582, mean ± SD). Variations of GSI values for females’ individuals indicated that the highest values were observed during January 2019 (18.31 ± 8.50, mean ± SE) and February 2020 (10.63 ± 2.97, mean ± SE) indicating peak spawning seasons of M. cephalus during those months. The distribution of ova diameter frequency indicates that the species spawns at least twice a year in batches. The current findings will improve our understanding of the biology of M. cephalus, an estuary migratory species, which will be useful in the subsequent management of similar migratory species in estuarine environments.