Bonnethead Shark
Latin Name: Sphyrna tiburo
Species: Fish
Conservation Status: Not Evaluated
Bonnetheads are the smallest of the 9 species of hammerhead sharks. Their heads are spade or shovel shaped with eyes on either side. Bonnetheads are gray-brown with small, dark spots on the sides and white on the underside. The position of their mouths is on the underside, indicating they are bottom feeders. Adults reach a maximum of 5 feet with the average being 3.3 feet. The record bonnethead weighed 24 pounds. Females are larger than males.
Range & Habitat (map)
Bonnetheads are only found in the western hemisphere. In the Atlantic Ocean, they are found from New England to the Gulf of Mexico and Brazil. In the Pacific Ocean, they are found from southern California to Ecuador. Bonnetheads travel long distances, following warmer water temperatures. During the winter, they move into deeper coastal water closer to the equator, and in the summer they move north and are found in shallower water.
Diet
Bonnetheads are bottom-feeders, eating crustaceans, including blue crabs and shrimp, along with mollusks, squid, and small fish.
Life History
In South Carolina, bonnetheads are commonly seen inshore from June to October. Bonnetheads have a cerebrospinal fluid that is used in chemical communication among the species, informing them when other bonnetheads are nearby. They are normally found in schools of 15 individuals but have been spotted in schools of hundreds or thousands while migrating. Females reach maturity at 2.5 feet. Bonnetheads are viviparous, meaning they give live birts, first relying on a yolk sac for nutrition but also developing a placental connection, like mammals. They have 4-14 pups that are about 14 inches long. Gestation is only 4-6 months, the shortest of all sharks.
Significance
The Port Royal Sound is thought to have the highest concentration of shark species on the east coast. Many sharks, including bonnetheads, are found here because the estuaries and marshes are great nursery habitats for juvenile sharks, offering plenty of food and protection.
Threats & How You Can Help
Bonnethead are often captured by small fisheries with shrimp trawls, nets, and longlines. They are marketed for human consumption and are also processed into fishmeal. Bonnetheads can be caught recreationally, but anglers must follow size and catch limits. Purchasing a Saltwater Fishing License is required to fish recreationally in the Port Royal Sound, and also contributes money towards conservation.