Multiple Mating by Females in the Chesapeake Bay Blue Crab Callinectes sapidus Population

Mature females of the Chesapeake Bay (USA) blue crab Callinectes sapidus population mate multiple times. Microsatellite DNA analysis of sperm stored in the spermathecae has shown that virtually all (~97%, 104 out of 107) females collected in a 2009−2010 study mated with at least 2 males. Enumeration of stored sperm revealed that despite multiple mating, some females did not have enough sperm to fulfill their lifetime reproductive potential, suggesting that female blue crabs may experience varying levels of sperm limitation. This could result from multiple factors. The average body size of males in the population has decreased, which reduces the amount of sperm that can be produced at a given time. The highly female-biased sex ratio of the population means that more females must be successfully mated per male than historically, placing greater demand on present-day males. Both of these factors are likely to have resulted from fishing mortality and sex-based management of the population. While much attention has been given to the management of female blue crabs, it is imperative to assess these organisms as a reproductive population in order to assure the continued health and maintenance of this ecologically important species