Multiple reproductive strategies in snow crab, Chionoecetes opilio: Physiological pathways and behavioral plasticity

We review the three major reproductive pathways displayed by snow crab, Chionoecetes opilio. Females can copulate in either a soft- or hard-shelled condition and also fertilize eggs with sperm stored in their spermathecae. Spermatophore partitioning and preservation mechanisms in the spermatheca plus postulated spermatophore removal abilities in males play central roles in shaping mating behavior. However, fitness consequences of the various strategies are enigmatic, Fecundity is influenced by both spermatophore source and female characteristics; also, egg production estimates are confounded by high loss rates and uncertainties surrounding brooding period. Males challenge the concept of ''maturity'' as they copulate both as morphometrically immature (MI) with small chelae and morphometrically mature (MM) with large chelae individuals. Reproductive opportunities for each male morph vary according to long-term population cycles influencing inter-male competition levels. Thus, during phases when MM males are abundant, reproductive opportunities for MI males are probably low; however, the window opens when MM males become scarce, We explore possible mechanisms that control whether males with small chelae either continue to molt and remain MI or attain full sexual maturity and, hence, probable terminal molt-status.