From December through February, the whales can be seen traveling southward in small groups along the California coast on their way to the bays and lagoons of Baja California where mating occurs and the females calve. In March and April, they once again travel north following the shoreline. The whales cover approximately 6,000 to 7,000 miles each way. It is believed that memory and vision aid them on their long migration. The California gray whale was designated the State Marine Mammal in 1975.