Variations in Total Width-Weight Relationships of Blue Crabs, Callinectes sapidus, in Relation to Sex, Maturity, Molt Stage, and Carapace Form

Abstract

ABSTRACT Equations expressing total width-weight relationships of blue crabs, Callinectes sapidus Rathbun (Decapoda: Portunidae), from the Ashley River, South Carolina, were calculated for each sex in relation to molt stage and for intermolt (Stage C) crabs of each sex in relation to maturity and carapace form. Sex, maturity, molt sign, and carapace form significantly affected width-weight relationships. Overall, males were heavier than females of equal width. Mature males weighed more than similar-sized immature males; in contrast, mature females weighed less than immature females of equal size. Crabs with short lateral spines were heavier than those of the same sex and width with long spines. Intermolt (Stage C) and premolt (Stage D) blue crabs of both sexes were heavier than recently molted (Stages A and B) crabs of the same sex. Premolt females were heavier than intermolt females; this difference was not observed for males. Ashley River crabs were generally heavier than crabs reported from Florida, Texas, or Virginia. These differences may not be real, however, because many variables affect width-weight relationships of blue crabs and only sex differences were reported in all but the present study. Geographical variation is known to exist in crab populations, but only well-defined comparisons between populations should be considered.