Dimorphic Growth Patterns on Scales of Striped Bass and Morone Hybrids from a Central Alabama River

Striped bass (Morone saxatilis) and Morone hybrids were studied in the Tallapoosa River downstream of Thurlow Dam from March through November 1980. Age and growth analysis revealed that over 80% of the striped bass scales had numerous false annuli, while none were observed on Morone hybrid scales. The presence of false annuli indicated interruptions in normal growth during the mid- to late-summer period. These interruptions were attributed to striped bass preferential selection of cooler water temperatures in mid-summer. The striped bass are believed to spatially separate themselves from much of their food, resulting in a reduced growth rate until water temperatures subside in the fall.