Southern Flounder Paralichthys lethostigma is the most commonly harvested flatfish in the north-central Gulf of Mexico (GOM) and supports a major inshore recreational fishery, yet knowledge of the species’ life history is greatly limited. The objective of this research was to describe the growth and reproduction of Southern Flounder in the Mississippi stock. Fish were collected during September 2014 to March 2016 using primarily recreational fishing techniques. Otoliths (n = 313) were sectioned to estimate age, and multiple length-at-age models were fit to total length (TL, mm) and age estimate (y) data. Gonadal tissue samples (n = 221) were preserved for histological analysis and used to classify reproductive phases. Length-at-age model fit was evaluated using Akaike information criteria, revealing that the three-parameter von Bertalanffy growth function best described the female-specific data (L∞ = 509 mm, k = 0.70 y-1, t0= -0.46 y). By fitting a logistic model to binomial maturity data, the mean length-at-50% maturity was estimated as 303 mm TL and mean age-at-50% maturity was estimated as one year for females. Histological indicators and gonadosomatic index (GSI) data were used to estimate that the spawning season lasts from November to January, and to classify Southern Flounder as batch spawners. These results will inform future stock assessments and management decisions for the GOM Flounder fishery
