Migration and reproduction patterns differ between crab populations along the East Coast and the Gulf of Mexico. A distinct and large scale migration occurs in Chesapeake Bay, where "C. sapidus" undergoes a seasonal migration of up to several hundred miles. In the middle and upper parts of the bay, mating peaks in mid to late summer, while in the lower bay there are peaks in mating activity during spring and late summer through early fall. Changes in salinity and temperature may impact time of mating because both factors are important during the molting process. After mating, the female crab travels to the southern portion of the Chesapeake, using ebb tides to migrate from areas of low salinity to areas of high salinity, fertilizing her eggs with sperm stored during her single mating months or almost a year before.