State, Brazil

The present work aims to study the size vs. weight relationship and the condition factor of a commercially important crab, Callinectes danae, from an estuarine complex located at Pernambuco State, Northeastern Brazil. After sampled, the specimens were measured on their carapace width (CW; mm) and weighted on their wet weight (WW; g). A total of 1,635individuals of C. danae were analyzed, being 881 males (53.8%) and 754 females (46.2%). Males were significantly larger and heavier than females (p < 0.05), the expected pattern to many crabs. The relationship WW vs. CW, described through the potency equation, was allometrically positive for both males (b = 3.12) and females (b = 3.02), a result also observed in other swimming crabs. The mean condition factor of males was 8.0 10-5 ± 1.5 10-5, and that of females was 11.5 10-5 ± 2.8 10-5, being significantly higher in females (p < 0.05), due to the fact that female gonads are heavier than that of males. The condition factor oscillated throughout the sampling year, for both sexes, which was related to the reproductive cycle. Key words: Allometry, biometry, estuary, relative growth. Huxley’s equation, is the most used to show this relationship, and represented by y = a.xb (Huxley, 1950). The x is the independent variable, related to other body dimensions of the species (dependent variables, y), that can be the size and the weight, respectively. The b is the allometric constant, which expresses the analogy between these two variables, and th