Morphometric relationships in blue crab males (Cardisoma crassum) and their relationship with sexual maturity

Abstract

On the mainland coast of Ecuador, 490 males of blue crab (Cardisoma crassum) were collected, with the aim of establishing morphometric characteristics and their relationship with sexual maturity. The individuals were measured considering the width, length and height of the carapace, as well as the right and left chelaes. The observed size ranges were 55.26-105.28 mm CW, 38.79- 77.90 mm CL, 48.46-24.74 mm CH. The right chelae had greater size in 52% of the individuals, the left one in 42% while, the 6% of the crabs were homochelos. Significant differences were found (p < 0.01) between the morphometric dimensions of the right and left chelae, as well as between the major and minor chela. Using linear regressions, it was observed that the relationships between the morphometric variables had a linear tendency with a high correlation coefficient (r ≥ 0.80). The values of the slopes (b) showed a negative allometric growth (b < 1) in most of the regressions, except for AlQM vs AnC (b = 1.29) and AnQM vs LC (b = 1.62) that were positive. Two groups of data were identified in the relationships between height and length of the chela vs the width and length of the carapace, which is possibly associated with the presence of juvenile and adult individuals. The point of separation between phases of ontogenetic development could not be detected by the absence of individuals of small sizes (< 55 mm CW).