MATING FREQUENCY AND VIABILITY OF STORED SPERM IN THE TANNER CRAB CHIONOECETES BAIRDI (DECAPODA, MAJIDAE)

ABSTRACT In captivity the percentage of multiparous Chionoecetes bairdi that mated prior to extrusion of their annual egg clutch was 62-100% and varied with sex ratio. In test groups where one male was held with eight or fewer females, over 90% of the females mated before egg extrusion but the percentage declined when more females were present. Ten was the maximum number of females mated by a single male during one breeding season. Viable egg clutches were produced by 97 and 71% of females using sperm stored in their spermathecae for one and two years, respectively. The remaining ripe females, held isolated from males, either produced egg clutches composed totally of nondividing eggs or never extruded eggs. Some nonovigerous females that had been isolated from males for two years were allowed to mate and subsequently produced viable eggs. Autopsy revealed that these females had both old and fresh sperm in their spermathecae, suggesting that the older sperm were not viable. Females forced to use stored sperm to fertilize three successive annual egg clutches produced only nonviable eggs in the third year.