Reproduction and Growth of the Commercial Sand Crab, Portunus pelagicus (L.) in Moreton Bay, Queensland

The biology of the commercial sand crab Portunus pelagicus is described in subtropical Moreton Bay, Queensland, Australia. The population samples were characterized by more males than females. Recruitment of O+ yr individuals occurred throughout the year, although it was greatest during spring. Crabs attained sexual maturity in their first year of life. After rapid growth of juveniles in shallow inshore habitats during summer and autumn, molting and growth slowed during winter. Von Bertalanffy 613 growth 19 functions were derived as follows 1 1 = 175 (1-e·l.597(t-0,203)) for males, and 1 1 = 170 (1-e-l.C-0.1a)) for females. Crabs moved further offshore as they in­creased in size. Ovigerous females were present throughout the year, although their proportion peaked during August-October. Maximum gonad development or male P. pelagicus was during May, whereas the peak period or female gonad activity occurred in July. The presence or many postmolt mature females with spermatophores in their spermathecae during May-June, confirmed those months as the major mating period.