Ovarian Development of Female Red Swamp Crayfish (Procambarus Clarkii) as Influenced by Temperature and Photoperiod

The effect of combinations of each of two photoperiods (14L: 10D and 10L:14D)and each of two temperatures (20°C and 27°C) on ovarian development in mature red swamp crayfish (Procambarus clarkii) was evaluated as measured by gonadosomatic index (GSI). Mean GSI for all treatments increased over time from an initial value of 0.063% to a final range of 0.481― 1.225% after 70 days. The effect of temperature and photoperiod varied at different sampling periods with temperature being significant at day 14 and photoperiod being significant at day 70. Interaction of the two variables was significant at day 56. Regression analysis indicated that the mean rate of increase of the GSI over time under the cold temperature (20°C), short photoperiod (10L: 14D) regime was significantly lower than those for all other treatments. Ovaries of females held under long photoperiod (14L: 10D) had the greatest mean rate of increase of GSI, but not significantly greater than that of the warm temperature (27°C), short photoperiod treatment. Mean rates of increase of whole body weight of crayfish in the warm temperature treatments were significantly greater than those for the cold water treatments but were not accompanied by significant increases in mean ovarian weights. Field data and laboratory results collectively suggest that temperature controls the onset of ovarian development which is accelerated by increasing day length.