Abstract
Photoperiod and temperature control ovarian growth and maturation in the crayfish Orconectes virilis, and increased water temperature induces egg laying in spring.Laboratory experiments with O. virilis from Alberta revealed that although ovarian growth will occur in warm water and darkness, or cold water and long-day photoperiod, subsequent exposure to spring temperature and photoperiod will not induce egg laying when the ovary has matured under these conditions. Complete ovarian maturation requires 4–5 months of low temperature and constant darkness.