On the population structure of Callinectes danae and Callinectes ornatus (decapoda, portunidae), in guanabara bay, Rio de Janeiro state, Brazil

Abstract

Guanabara Bay forms an estuarine ecosystem that is degraded on account of the action of several contamination sources. Despite this, it maintains an important fishery production that is mostly composed by Callinectes danae and Callinectes ornatus swimming crabs. Thirty-three trawlings were conducted from August 2002 to September 2003 in different locations in this bay, as well as visits to the Z-8 fishery colony, and cruises with fishermen. A total of 2,275 specimens were captured, of which 1,445 were C. ornatus and 830 C. danae. Their largest captures occurred in summer, being C. ornatus the most captured species during the season. Continuous reproductive pattern was only verified for C. danae. Capture of adult individuals was higher than that of juveniles for both species and sexes. The sex ratios obtained for C. ornatus and C. danae were significantly different from the expected 1:1. Growth in weight showed a very similar pattern for both species. The fishery recruitment to Guanabara Bay`s trawling fleet started in autumn for C. danae (35.00 mm individuals) and in spring for C. ornatus (30.00 mm individuals).