Bluegill collected in four heated reservoirs in Texas (Lake Bastrop, Lake Nasworthy, North Lake and Lake Colorado City) were aged by scale-reading. Back-calculated length frequency distributions of scale-aged bluegill matched with the observed length-frequency distributions of bluegill caught during periods of greates annulus formation except for back-calculated lengths based on samples taken by gear with a mesh size that only captured the largest individuals of a year-class.