Thermal enrichment of a reservoir and the effects on annulus formation and growth of largemouth bass, Micropterus salmoides

Analysis of largemouth bass scales, including those from 48 tagged and recaptured fish, revealed that many scales had more ‘annuli’ than possible for the age of Flint Creek Cooling Reservoir. The mark‐recapture data indicated the formation of one supernumerary annulus per year for most bass. Time of formation of true and supernumerary annuli and the causative factors are discussed. Growth of bass from this reservoir greatly exceeded that reported for thermally unaltered reservoirs of Northwest Arkansas, due to the existence of a nearly year‐round growing season, a result of thermal enrichment. The relationship between the ratio of electric power output to reservoir surface area and growth offish was evaluated with reference to published data on cooling reservoirs.