Fig. 6.—
The population age structure for free-ranging killer whales (Orcinus orca) of the eastern North Pacific (NSR, northern and southern resident population from 1975 to 2015) for males and females of known-age (NSR) and for all NSR animals (estimated age + known age, NSRt) as reported on 31 December 2014. The population age structure of captive killer whales at SeaWorld Parks and Entertainment (SEA) includes known-age animals and animals whose age was estimated based on length at capture. No differences (P > 0.05) were detected in the distribution patterns of age group categories among the 3 population types prior to the 41- to 50-year category. In that category, the number of animals present as a proportion of the living population for NSR was lower than that of the value for animals of estimated age NSRt (Z = 2.38, P = 0.017).