Weight/carapace width relationship and condition factor in Dilocarcinus pagei Stimpson (Crustacea, Trichodactylidae) in Sao Jose do Rio Preto, Sao Paulo, Brazil.

The biology of freshwater crabs has been little focused in the carcinology literature, mainly in relation to Dilocarcinus pagei Stimpson, 1861. This study alms to analyze weight/size relationship and temporal/seasonal variations of the condition factor, comparing with species biology. Individuals were monthly captured at Sao jose of Rio Preto Dam's (Sao Paulo), during October 1994 to September 1996, and 962 specimens (534 males and 428 females) measured (CW = carapace width) and registered to weight (WW = total wet weight). Empirical points of WW/CW relationship were analyzed to each sex and submitted to regression analyses by power function (y = ax(b)), and represented by:WWMales = 0.0002CW(3.08) and WWFemale = 0.0005CW(2.82). Condition factor were monthly and seasonally calculated, with females' condition factor 2.5 times larger than of the males, due to the largest size/weight of the ovary. In general the summer was characterized by the smallest average of condition factor (reproductive period), contrasting with the largest verified in the winter (gonad reorganization). The results obtained are focused for the first time in the carcinological literature, being very important in population management and preservation of this species, that it comes being explored intensely and used as bait in the sporting fishing.