The crayfish Orconectes virilis: survival in a region with severe winter conditions

Abstract

An attempt was made to determine whether Orconectes virilis from a shallow river system in eastcentral Alberta has evolved a behavioral or physiological response which allows it to survive under the severe winter conditions of this region. From observations and experiments in the field and laboratory it was concluded that O. virilis cannot withstand even a small degree of freezing, and does not actively burrow into mud to escape the danger of freezing. The only observed behavior contributing to winter survival is a seasonal movement of mature animals to deeper water, and this is apparently associated more with gonadal maturation than with winter survival. The results from these experiments indicate that immature animals suffer a higher winter kill than do mature animals, and that winter survival of the species in any region is dependent upon the presence of habitat in which there is some water which does not freeze to the substratum at any time during the year.