Early Life History of the Northern Pike, Esox lucius L., with Special Reference to the Factors Influencing the Numerical Strength of Year Classes

Abstract

The early life history of northern pike was studied to determine the relationship of adult pike abundance to the strength of resulting year classes and the existence and chronology of critical survival periods, along with the nature and origin of the mortality mechanisms involved. Adult abundance and the strength of the resulting year classes were not directly related. Two critical survival periods were located, one during the embryo stage between fertilization and closure of the blastopore, and the second between hatching and the termination of the alevin stage. The mortality during these periods may result from toxic concentrations of iron compounds or from excessively rapid temperature change. Growth, food utilization, and oxygen, ammonia, and sulfide levels in the nursery slough did not appear to influence survival. Greatest survival of naturally reared fingerlings will result from stabilization of water levels in the nursery areas. Water is required for at least 3 months after egg deposition if the best survival is to be obtained.