Reproductive potential of female eastern Bering Sea tanner crab

Abstract

Changes in abundance and sex ratio can contribute to variation in the reproductive potential of a population. The commercially important Bering Sea Tanner crab (Chionoecetes bairdi) are distributed throughout the north Pacific Ocean and display cyclical population dynamics. The goal of this study was to examine how fishing pressures and population dynamics affected the reproductive potential of Bering Sea Tanner crab to better inform sustainable fishery management. I quantified female stored sperm levels and fecundity for both primiparous (in their first reproductive cycle) and multiparous (in their second or later reproductive cycle) crab to examine spatial and temporal variation in reproductive potential. Multiparous female crab had higher spermathecal load than primiparous ones, but spermathecal load varied widely across female size. Higher sperm cell counts were associated with visual indication of fresh ejaculate for primiparous crab but not for multiparous crab. Sperm cell counts increased with increasing spermathecal load for both primiparous and multiparous crab, although the slope of the regression line varied for the two categories. Female fecundity was highest in crab in their second year after the terminal molt to maturity and was lower in the first year and in the third and subsequent years. Female fecundity (size-corrected) did not differ among management areas. Measures of mature female sperm storage and quantification of reproductive stage can provide fishery managers with an early warning of reproductive failures.