Population biology of Xiphopenaeus kroyeri (Heller 1862) (Decapoda: Penaeidae) from Ubatuba Bay, Sao Paulo Brazil

The population structure and abundance of Xiphopenaeus kroyeri (Heller, 1862) were analyzed during monthly samples from October 1992 to September 1993 in Ubatuba Bay (23 degree 26 theta S and 45 degree 02 theta W), Brazil. Sampling was carried out at two parallel transects: one of them located in its midregion and the other at the mouth of the bay. After trawling, shrimps were separated from other benthic organisms, sexed, and counted. Their total length was also measured, and the degree of gonadal development was assessed. Xiphopenaeus kroyeri, the most common penaeid species in the bay, was recorded in all samples, but its abundance decreased from November to March. Size ranged from 14.3 to 118.3 mm in males and from 12.7 to 133.6 mm in females, suggesting a slight sexual dimorphism related to body size. Males prevailed during most of the year; whereas, females predominated during summer and midwinter. Based on the percentage of mature females during this study, two main reproductive periods were identified, occurring in spring and autumn. Despite some breeding activity throughout the year, such a trend indicates that the population follows a tropical/subtropical reproductive pattern.