The growth and reproductive cycle of a landlocked population of blueback herring (Alosa aestivalis) were evaluated in Lake Theo, a North Texas reservoir. Scales were collected and length, weight, and gonad characteristics were recorded for individual herring. Herring reproduced each year of the study. Average size of Age I herring ranged from approximately 70 to 170 mm total length (TL). Average size of Age II herring was approximately 200 mm TL and maximum size was 237 mm TL. Scale annuli formation in immature fish began in April; spawning marks occurred on scales in late summer. Herring matured at Age I or II and lived 2-3 years. Size at sexual maturity was 175-200 mm TL. Fecundity ranged from approximately 30,000 to 60,000 eggs (> 0.2 mm diameter) for females 190 to 216 mm TL. Gonadosomatic indices suggested protracted spawning from April through July with a peak in May and June. Spawning temperatures ranged from 21° to 25°C; spawning ceased above 27°C.
