Comparative Pattern of Reproductive Traits in Labeo rohita (Hamilton 1822) from Six Tropical Rivers of Ganges Basin: A New Insight

Abstract

The pattern of reproductive traits of six wild populations was studied for a native, commercially important Indian major carp, Labeo rohita. It was examined whether environmental conditions of water and temperature could explain interpopulation variation in the reproductive traits of this fish. The results indicated that nearby populations subjected to slight variation in environmental conditions exhibited a significant variation in reproductive traits. No significant differences (P < 0.05) in reproductive traits were noticed in the same river in different years (2009–2011). It was noticed that with increase in length of fish the absolute fecundity increased and peaked at the maximum length whereas, the relative fecundity remained constant as the length of fish increased except in river Sharda, where it was highest at lower size classes. It was also noticed that males matured earlier than females in all the selected populations. A significant (P < 0.05) correlation was observed when fecundity was plotted against total length, total weight and ovary weight of fish. The ova diameter was higher in rivers Sharda and Betwa and comparatively similar in other rivers. The peak of the sexual activity was observed from May to August in both sexes suggesting no variation in the reproductive cycle of this species over the years. These results will help in further studies on the population assessment of this species.