The Effects of Artificial Aeration on the Depth Distribution of the Crayfish Orconectes virilis (Hagen) in Two Michigan Lakes

Abstract

Crayfish (Orconectes virilis) usually exhibit seasonal depth distributions in certain northern Michigan lakes based on sex, age and water temperature. After releasing attached young in shallow water, the adult females typically migrate to deeper cold water while the adult males remain in the warm shallow water. This pattern was thought to be related to the sexual maturation cycle. However, when two lakes were artificially aerated and destratified with compressed air, both sexes distributed throughout the lakes. It is, therefore, postulated that under normal conditions of thermal stratification, the social aggression of the larger males forces the females into deeper, colder water and that this aggression is temperature-related. If oxygen or some other factor is not limiting, 10 C seems to be the lowest temperature selected by O. virilis during the summer.