Reproductive Success of Multiparous Female Tanner Crab (Chionoecetes bairdi) Fertilizing Eggs With or Without Recent Access to Males

Abstract

Sperm storage in female crabs is assumed to provide resiliency in population reproductive potential for exploited crab stocks with male-only harvest restrictions. However, contrasting results have been reported for the reproductive success of female Tanner crab (Chionoecetes bairdi) relying on stored sperm for fertilization. Ovigerous multiparous female C. bairdi were collected and held in the laboratory in the absence of males from hatching to extrusion or collected after hatching and extrusion of a subsequent clutch in situ in Glacier Bay, Alaska. Females were classified into two groups based on extrusion site, LE (laboratory) or FE (field). Mating of multiparous females was important for maintenance of reproductive potential as sperm reserves were likely insufficient for full fertilization of an additional egg clutch from stored sperm in 44% of LE females. High incidence of fresh grasping marks for FE (97%) versus LE (4%) females and significantly higher sperm reserves indicated that most FE females were likely to have recently mated. Mean postextrusion spermathecal load and sperm cell counts increased significantly from 0.21 to 0.44 g and 2.00 × 107 to 9.35 × 107, respectively, between LE and FE females (p 99%), with similar fecundity. Characterization of spatiotemporal trends in mating status, sperm reserves and egg production in C. bairdi may be valuable for understanding natural variability in reproduction and possible fishery effects on population reproductive potential.