In this study, blue catfish were sampled from tidal reaches of the Chesapeake Bay in Maryland (Nanticoke River, Broad Creek, Marshyhope Creek, and Patuxent River) from March - October and at some sites, during specific times of the year. All fish were analyzed with histology to assess reproductive stage (immature, pre-spawn, and post-spawn) and plasma was collected for multiple endpoints including 17β-estradiol (E2), calcium, and total protein. The histology results showed that the number of vitellogenic, pre-spawn females began to increase in April with the greatest number of individuals observed in May, which gradually declined through July. In males, the greatest number of pre-spawn individuals was observed in April and gradually declined through June. Additionally, female E2 levels showed a trend similar to the histology results, indicating that this plasma endpoint was beneficial for assessing reproductive changes over time. Collectively, these results showed typical spawning patterns observed in blue catfish and future work will need to be done across different watersheds to provide additional data for management purposes.