Assessment of interspecific variations in the reproductive patterns of co-existing female mullet species inhabiting intertidal mudflats of Indian Sundarbans

Abstract

Mullets are considered as the most abundant and important species with respect to the local fisheries of the Indian Sundarbans. Being economically important, their natural population stock is of much priority for which their reproductive biology needs to be clearly understood followed by the projected trends in recruitment pattern. The study was concentrated towards female specimens as the male specimens were significantly lower in number. The purpose of the study was to investigate and highlight the seasonal pattern of the reproductive cycle through analysis of morpho-gonadal parameters, percentage frequency of maturity stages and flow-cytometric records of ovarian cells of female mullet species, which has not been reported in any other studies till date. The study was conducted in mangrove eco-region situated at the central part of Indian Sundarbans in the main estuarine network of Matla River and Bidya River from April 2015 to January 2018. Results suggested that the prominent peaks of reproductive parameters are indicative of the spawning time for Osteomugil cunnesius during pre-monsoon season (February–May) and in post-monsoon season (October–January) for Chelon parsia and Planiliza subviridis. Seasonal variation of environmental conditions indicated an influence on timing and duration of the reproductive mechanisms of mullets. Evidences suggested temporal segregation of reproductive maturation among the three mullet species with similar feeding niches. The present study highlights an inter-specific reproductive expression of three co-existing female mullets to avoid the struggle for food resources necessary for reproductive maturity to ensure recruitment success under favourable environmental conditions in estuarine intertidal mudflats of Indian Sundarbans.