Age Determination of the Spider Crab Maja squinado and the European Lobster Homarus gammarus by 228Th/228Ra Chronology: Possible Extension to Other Crustaceans

Abstract

A method of age determination was developed on carapaces of the spider crab, Maja squinado Herbst and European lobster Homarus gammarus L., by measuring the natural radionuclides activity ratio, 228Th/228Ra in the exoskeleton. This method allows the determination of the time elapsed since the preceding molt of the animal. It was successfully tested on five spider crabs and four lobsters which had molted in captivity and therefore had a carapace of known age. It is probable that the method could, with some reservations, be extended to all marine Decapod Crustacea bearing a well calcified exoskeleton.