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larger size than males: all pikeminnow identified as males in this and other studies have been less than 800 mm long; females from the Colorado River have been as large as 965 mm. New, gender-specific growth curves were constructed based on average annual growth increments. These curves indicated that females grow faster than males, but do not necessarily live any longer. Because all very large pikeminnow were found to be females, the female-specific growth curve was employed to estimate age of the largest fish. Based on these findings, the average age of 900-mm long pikeminnow was revised down to 39 years from an earlier estimate of 56 years. Average body condition (Kn) for almost all length-classes of pikeminnow significantly declined between the early and recent study periods in both reaches. Mean Kn of pikeminnow 500-599 mm long was relatively constant in the upper reach during 1998-2000, but significantly increased in the lower reach during the same time period. As previously reported, length-frequency and scale-aging analyses indicated that many fish recruited from the 1985-1987 year classes, accounting for an increase of adults in the mid-1990s. Especially high spring runoff in 1983-1984 evidently created favorable environmental conditions that resulted in high reproductive success and survival of young during 1985-1987, years of moderately high spring runoff. New data presented here revealed more recent recruitment from the 1990-1994 year classes, although this was lower than for the 1985-1987 year classes. The upper reach length-class containing the greatest percentage of individuals during 1991-1994 was the 550-599-mm-group; however, this shifted to the 600-649-mm-group during 1998-2000. This increase in length of the most common-size fish resulted from the pulse of fish produced during the mid 1980s continuing to grow and work its way up through the age classes. An experimental exercise in predicting change in adult abundance using population point estimates, growth rates, length frequency, and survival estimates was attempted with mixed results. The estimated number of individuals capable of growing to adult size by the following year was calculated and added to the current-year population point estimate of adults; the number of adults expected to die based on the average annual mortality rate was then subtracted. The resulting predictions of adult numbers in the following year was calculated for all years for which the requisite values were available. These were compared ix