POPULATION-STRUCTURE OF HEPATUS-PUDIBUNDUS (DECAPODA, CALAPPIDAE) IN FORTALEZA-BAY, BRAZIL

The population of Hepatus pudibundus crabs in Fortaleza Bay, Ubatuba ( Sao Paulo), was studied with emphasis on structural aspects such as se x-ratio, size, and reproductive time, based on the number of ovigerous females and on seasonal distribution. Crabs were sampled monthly from November 1988 to October 1989 using a shrimp fishing boat equipped wi th two otter-trawls. A total of 405 specimens (males: 133 adult and 34 immature; females: 175 adult, 19 ovigerous and 44 immature) were samp led. Mean animal size, based on the measurement of carapace width (CW) , was 53.27+/-10.59 mm for males and 46.7+/-7.86 mm for females. indiv idual size frequency distribution was bimodal and skewed to larger siz e classes in males, and unimodal and normal in females, with the large st numbers occurring in March (83), May (70) and July (50). Reproducti on occurred throughout the year, with a high incidence of ovigerous fe males from January to April 1989. The large number of females was prob ably due to the reproductive strategy of the species. The heterogeneou s seasonal distribution was probably related to migration to other are as (open sea, estuaries) because of environmental conditions or partic ular demands during the developmental phase.