Regression analyses and delta-lognormal models were used to investigate whether river discharge and environmental variables significantly affected relative abundance of brown shrimp, Farfantepenaeus aztecus, in the northern Gulf of Mexico. Significant negative relationships were found between mean river flow during winter and spring months and catch rates (CPUE) off Texas, Louisiana and Mississippi/Alabama. However, during the same months significant positive relationships between CPUE and the variation in mean river discharge were found for each state. In Texas and Louisiana, delta-lognormal models revealed depth zone was the most significant variable (P≤0.001) in describing distribution, while time of day (P≤0.001) was most significant in describing CPUE and also distribution and CPUE in Mississippi/Alabama. These results suggest that brown shrimp relative abundance is effected by river discharge, while gulf-wide environmental variables exert no influence, except dissolved oxygen concentrations affecting distribution off Louisiana.