We evaluated the incidental catch of the blue crab in artisanal fisheries through the analysis of sex ratio, catch per unit effort, net positioning, and size in which the capture probability was 50% (P 50). The specimens were collected from 2011 to 2013 in the estuary of Patos Lagoon, southern Brazil. The analysis showed a higher occurrence of males. Variations in the catch per unit effort showed greatest abundance values close to the mouth of the estuary. Catch per unit effort was similar when comparing fishing seasons and net positions. P 50 indicated a low selectivity of the nets since it varied between studied areas but stayed below the size at first maturity. Catches indicated a greater effort on males, since females migrated to spawn in the ocean area adjacent to the estuary during the fishing period studied. The spatial variation of the catch per unit effort showed heterogeneity in fishing catches. Thus, optimal management of the resource should consider the particularities of each area.