Reproductive biology of the freshwater prawn Macrobrachium rude (Decapoda: Palaemonidae)

Abstract Macrobrachium rude is a notable freshwater prawn in Bangladesh owing to its palatability and considerable market value. This study examined the reproductive biology of the species for the first time, encompassing sex ratio, size at sexual maturity, reproductive pattern, egg size, and fecundity. A total of 917 individuals were examined, with males ranging from 4.1 to 7.4 mm carapace length (CL) and females from 4.8 to 14.0 mm CL. The sex ratio exhibited a male bias in the smaller size group and a female bias in the larger size group. The size at which 50% of females reach maturity was estimated to be 8.4 mm CL. Ovigerous females had no mature ovaries right after spawning; however, the percentage of mature ovaries increased as the eggs developed, approaching nearly 100% prior to hatching, suggesting the potential for multiple spawning of females within a reproductive period. Egg size was not correlated with female size but increased with development. The total number of eggs was significantly larger in larger females. The results of this study will help in developing sustainable management and conservation approaches for this significant fishery.