Maturity and Breeding of the Pacific Edible Crab, Cancer magister Dana

Abstract

The breeding procedure of C. magister is described. Contact between the male and female in the pre-mating embrace causes marks on the exoskeletons. These "mating marks" are used as an indicator of breeding activity of male crabs. Differences in intensity of mating marks are discerned, and these are interpreted as evidence of polygamy under natural conditions.Examination of vasa deferentia and sampling of male breeding crabs has indicated that onset of maturity in the Queen Charlotte Islands occurs at a carapace width of about 110 mm, or at approximately three years of age. However, sexual activity is not appreciable until the width is about 140 mm.Female crabs are mature at a carapace width of 100 mm, at about two years.