Age, growth, and food of northern pike in eastern Lake Ontario
Northern pike ( Esox lucius ) from eastern Lake Ontario were sampled with gill nets and trap nets in 1972-1973. Fish of age-groups IV, V, and VI were predominant in the catch. Although males were slightly longer after the 1st yr of life, females gained a 25-mm advantage in the 2nd yr and a 30-mm advantage in the 3rd yr. In later years, the increments of growth of males and females were similar. All males were mature after 2 yr and females after 3 yr. The stomachs of northern pike contained only fish; the alewife ( Alosa pseudoharengus ) was the principal forage species consumed. Electivity indexes for alewives, white perch ( Morone americana ), and yellow perch ( Perca flavescens ), the three most common species in the diet, indicated a positive selection for alewives that increased from June to October during a period when the relative abundance of alewives steadily decreased.