Reproduction / Life History

The Bull shark is a viviparous species that gives live birth to its young.  While the young are inside their mother, they receive nourishment from a yolk-sac placenta.   The estimated gestation period is 10-11 months, with the litter size of this shark being 1 to 13 pups, which are 60 to 80 centimeters in length.  Males of this species usually reach sexual maturity between the ages of 14 and 15 years, while females reach maturity at around age 18.  Females typically give birth in late spring and early summer, but these times can vary depending on habitat.  For instance, sharks that live in the close proximity of Nicaragua can give birth all year round, but those that live in most other regions of the world do not. Male Bull sharks participate in courtship with the females, and this often results in injuries and bite marks to the females.  During courtship the male shark bites at the female and will grasp one of the female’s pectoral fins in his mouth.  If a female allows a male to mate with her, the male will insert his claspers into the female, which are extensions of the pelvic fins used to transfer sperm into the female’s cloacae.  Bull sharks do not take care of there young after birth like most other shark species do, but they usually give birth in shallow coastal regions which protects them from most predators.  Bull sharks always give birth in salt water even though it is possible for them to give birth in fresh water.    An adult bull shark usually grows to be around 7.5 feet long, and around 280 pounds but can grow up to 10 feet and weigh over 300 pounds.  Female sharks usually grow to a larger size than the males.

           Photo by: Tobey Curtis