Length, age, and growth of two species of juvenile black bass in a trout tailwater

Juvenile shoal bass Micropterus cataractae and largemouth bass M. salmoides were studied in the Upper Chattahoochee River, Georgia to assess environmental variation on fish length, age, and growth.  Juvenile shoal and largemouth bass were sampled in summer 2004 along a longitudinal temperature gradient: below Morgan Falls Dam (MFD), Cochran Shoals (CS), and Paces Mill (PM).  Differences in shoal bass mean length were observed between MFD and CS and between MFD and PM.  Largemouth bass illustrated a similar trend.  Mean daily growth rates of shoal bass while in the hatchery were greater than at ≥ 30 days post-stocking.  Largemouth bass growth rates were higher than shoal bass at the same sampling interval.  Shoal bass exhibited natural otoliths marks corresponding to stocking dates.  Post-mark daily rings were constricted and difficult to discern.   As a result, mean daily ages were typically underestimated (range: 3-9 days).  Largemouth bass were, on average, two days older at PM than at CS.  Mean lengths, growth rates, and ages of shoal bass and largemouth bass downstream from Morgan Falls Dam appear to be concomitant with longitudinal increases in water temperature.