Population structure of Hepatus pudibundus (Decapoda: Aethridae) off the coast of Sergipe State, northeastern Brazil

Shrimp trawling is an important socioeconomic activity but catches a large number of non-target species, including Hepatus pudibundus. This study aimed at assessing the population structure of H. pudibundus, analyzing its sex ratio, length distribution, size at first morphological maturity and biometric relationships, and identifying latitudinal patterns. Four samples of 6 kg (shrimps plus by-catch) were monthly collected in March/2015-May/2016 in Pirambu, Sergipe. Carapace width (CW) and length (LC), and total weight (TW, g) were measured. Sex and stage of morphological maturity were defined. A total of 240 individuals was collected from all samples and the sex ratio did not differ from 1:1. This was observed in low latitudes, but females dominated in higher latitudes. The carapace width was 20.8-60.1 mm for females and 19.1-60.8 mm CW for males. Larger sizes were observed in higher latitudes. The estimated carapace width-length relationships for females and males were not significantly different (CL=0.6764+0.7390.CW; sex grouped). The estimated weight-length relationship was TW=0.0004.CW(2.8568 )for females and TW=0.0001.CW(3.1225 )for males. When compared with previous studies carried out throughout the Brazilian coast, slope values (b) for weight-length relationships were higher for males. The length at first morphological maturity for females and males was 28.9 and 29.6 mm, respectively, the lowest ever recorded for this species, reflecting the occurrence of smaller sizes in lower latitudes. These results are the first obtained for northeastern Brazil.