A Review of Size at Maturity in Male Tanner (Chionoecetes bairdi) and King (Paralithodes camtschaticus) Crabs and the Methods Used to Determine Maturity

This paper reviews existing studies on the size of sexual maturityfor male Tanner or snow crab (Chionoecetes bairdi), a brachyuran,and the anomuran red king crab (Paralithodes camtschaticus).In this report the term sexual maturity is denned as the abilityto reproduce. A variety of indirect and direct methods thathave been used to determine maturity are reviewed. Examiningthe vas deferens for the presence of spermatophores was usefulin determining the size at which males first become mature.Breeding experiments in the laboratory demonstrated that mostmales, from both species, that produced spermatophores couldbreed with soft-shelled mates. Males of both species can breedat smaller sizes than do females. Morphometric techniques basedon reproductive tract weights and chela morphometry overestimatedthe sizes at which males mature in both species. Previous experimentsfor Tanner crab, which have internal fertilization, suggestsmall mature males can fertilize two to five females. Breedingexperiments showed recently matured red king crab do not appearto be able to fertilize more than one female per breeding season,while males nearing harvestable size can fertilize more thanone female. Breeding experiments and in situ observations of grasping pairsappear to be the most feasible methods for identifying malesize at maturity for these species. The value of morphometricestimations for determining when males mature is questionable.