Reproductive biology of Exopalaemon carinicauda (Decapoda, Palaemonidae) in the Hampyong Bay of Korea

Investigations on reproductive aspects of the ridgetail prawn, Exopalaemon carinicauda were made in the Hamopyong Bay of Korea from January 2003 to December 2004. Males and females comprised 31.6% and 68.4% of the total sample, respectively. There was a predominance of females in the sex ratio. Females progressively dominated the larger size classes. Female maturity was determined by the size of ovigerous females and of females with maturing ovary. The size at which 50% of females are mature is estimated as 14.97 +/- 4.63 mm CL. The main breeding season, from June to August, coincided with higher gonadosomatic indices. A significant differences in ovarian weight between females with non-eyed and with eyed egg stages was found. In this season, ovaries rematured during embryonic development, indicating a potential for multiple ovulations. Based on the incubation time of the embryos, females seemed to have at least two broods per year. Brood size showed a positive allometry to female body size with no apparent egg loss during incubation. The egg volume increased by 91% from 0.78 +/- 0.17 mm(3) at non-eyed eggs to 1.50 +/- 0.34 mm(3) at eyed eggs. Based on dry weight, an egg batch averaged 14% of female weight, indicating an investment in egg production similar to that in other marine shrimps, but lower than that of freshwater shrimps.