Effect of photoperiodism on ovarian maturation of female freshwater prawn Macrobrachium lamarrei lamarrei {H. M. Edwards 1837}

Abstract

The effect of photoperiodism on the ovarian maturation and ovarian indices of female freshwater prawn Macrobrachium lamarrei lamarrei {H. M. Edwards, 1837} was investigated in the laboratory over a period of 28 days. 90 healthy specimens of M. lamarrei lamarrei were taken with uniform weight (0.286-0.325gm) and length (35-40 mm). The experimental prawns were divided into three groups Viz, control, continuous dark and continuous light. The ovarian maturation was assessed by microscopic and histological observations. G.S.I (ovarian indices) of all the 3 groups has been calculated. The result from this study revealed that in continuous dark the ovaries are in more developed conditions as compare to control and continuous light. The GSI revealed after the study shows marked difference as that of control group. Therefore, it was concluded that complete darkness is useful to accelerate ovarian maturation in M. lamarrei lamarrei.