Reproductive biology of the speckled shrimp Metapenaeus monoceros (Fabricius, 1798) (Decapoda: Penaeidae) in the gulf of Gabes (Southern Tunisia, Eastern Mediterranean)

摘要

The present study describes the reproductive biology including sex-ratio, ovarian maturation, size at sexual maturity and spawning season of the speckled shrimp Metapenaeus monoceros (Decapoda: Penaeidae) in the Gulf of Gabes (Southern Tunisia, Eastern Mediterranean). Samples for biological investigations were collected from the commercial catches of trawlers and tramel nets from January 2007 to January 2008. A total of 4226 specimens ranging from 46 to 170 mm TL (total length) and 0.656 to 39.554 g BW (body weight) were analysed in the present Study. Females outnumbered males by 1.5 to 1 (2533 vs. 1693 individuals). Sexual maturity stages were classified into five categories for females and four categories for males based on the visual observation of gonad's coulour and shape. The spawning season was estimated based oil monthly changes of gonadosomatic index, condition factors and gonadal Maturity stages. The spawning occurred twice a year, with the first peak in May-June and the second more intensive one in October-November. The size at sexual maturity (TL50) was 76.5 mm TL for males and 122.3 mm TL for females. The data presented in this study would be useful for the sustainable management of the speckled shrimp fishery in the Gulf of Gabes.