Bull sharks are viviparous, meaning that they give live birth. The gestation period is about one year, usually during the summer months but sometimes in early autumn as well. Bull sharks usually migrate to river mouths to mate and have their young. Pups are about 60 cm (24 inches) long, and mothers give birth to 5 to 15 pups at a time. Coastal lagoons, river mouths, and estuaries with low salt contents are common nursery habitats.