Some population aspects of Charybdis (Charybdis) hellerii (A. Milne-Edwards, 1867) (Decapoda, Portunidae) at Sergipe River Estuary, northeastern Brazilian coast

The present study provides some parameters of the population biology of Charybdis (Charybdis) hellerii (A. Milne-Edwards, 1867), an invasive swimming crab inhabiting the estuarine portion of the Sergipe River, northeastern Brazilian coast. Samplings were carried out monthly from July 2015 to June 2016 with baited traps. The species was the second most abundant caught organism and its relative abundance ranged over the time from 11 to 59%. Sex ratio was 1:1 and all individuals were morphologically mature. Males were bigger than females. Ovigerous females were observed year-round and the smallest one was 31.35 mm carapace width. These findings show that the population is well established on the Sergipe coast. The entire distribution, and possible impacts, of C. (C.) hellerii on local environments need to be evaluated in further studies.