Allometry in Callinectes bellicosus (Stimpson, 1859) (Decapoda: Brachyura: Portunidae): single-power model versus multi-model approach

We examined the length-weight relationship (LWR) in Callinectes bellicosus (Stimpson, 1859) (Brachyura: Portunidae). The power model W = aLb is practically the only model used for allometry in aquatic animals, where the allometric coefficient b is considered as constant and determined by the overall size of the animal. We tested the hypothesis that the single-power model is not adequate to describe LWR in C. bellicosus. Five models were tested, and the best selected by multi-model approach and information theory. A total of 4,089 individuals of C. bellicosus (2,531 males and 1,558 females) were collected from the Gulf of California, Mexico and measured. According to the bias-corrected form of Akaike Information Criterion, a cubic function on log-transformed data was the best model in males, whereas the quadratic and cubic models showed very similar support for females. Overall, Fulton's condition factor (FC) increased with size, but a significant increase of the factor was observed in the last size class of both sexes. Our results show that the allometric coefficient changes progressively as size increases in C. bellicosus.