Bull Sharks   


Characteristics and Distribution

Unlike most of the other sharks described in this site, bull sharks are not particularly striking in their form or coloration. Their habits and interactions with humans do, however, make them very memorable. Bull sharks are greyish, heavy bodied sharks with distinctly short, bluntly rounded snouts and small eyes. They are reported to reach nearly 3.4 m (11 ft) at their maximum length. Found in all tropical and subtropical seas and common in water less than 30 feet deep (9.4 m), bull sharks can, unlike many fishes, can tolerate a wide range of salinities. Bull sharks enter estuaries and creeks, sometimes moving hundreds of miles upstream. A population of these sharks is found in Lake Nicaragua. These sharks have been documented to move readily between the lake and the Caribbean. Bull sharks have also been reported in the Mississippi, Amazon, Tigris, and Gambia rivers as well as Lake Ysabel in Guatemala.

Life History

Bull sharks are estimated to live to the age of 24. Females grow larger and live longer than males. They are able to reproduce for the first time between the ages of six and fifteen. Following a year long preganancy, females give birth to live young in shallow nursery grounds in estuaries and near river mouths. In Florida coastal lagoons, females were found to arrive from deeper water in late April and give birth in June or July. Bull sharks give birth to 1-13 live young. Adults apparently leave the lagoons after giving birth. Juveniles remain in lagoons and nearshore coastal waters until reaching the age of maturity. The use of different habitats by adult and juvenile sharks is thought to be an adaptation that helps improve the survival of young sharks through a decreased risk of being preyed upon by the adults. Bull sharks are often found in water less than 30 feet deep.

The bull shark, like the tiger shark, is known to be extremely opportunistic and versatile in its feeding habits. The most common prey items are bony fishes (such as tarpon, catfish, mullet, flatfish, jacks, grunts, etc.) and other sharks. Rays seem to be particularly important components of its diet as well. Invertebrates including, but not limited to, crabs, shrimp, squid, and sea urchins have been identified in stomach contents. Sea turtles, birds, dolphins, and land animals that have been washed out or dumped at sea are also readily eaten.

Interactions with Humans

The bull shark may be the most dangerous of all the sharks occupying the coasts of tropical and subtropical waters. This species is less distinctive than the Tiger or White shark and is thought to be responsible for many of the attacks that are attributed to sharks.

Threat from Humans

Because of their large numbers and availability near shore, bull sharks are taken in fisheries throughout the world. Their flesh is used for human consumption and the skin is often used as leather.

     

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