According to the International Shark Attack File, bull sharks (Carcharhinus leucas) are among the top 3 shark species implicated in shark attacks. They are likely a greater threat than other large shark species because they prefer to live in shallow, murky coastal waters, and can even survive in freshwater for a period of time. So, they have more potential to interact with humans than sharks that spend more time offshore.
Other names for the bull shark include the Zambezi shark, Swan River shark, Lake Nicaragua shark, cub shark and estuary shark. Many of these names refer to the shark's tendency to be found in rivers, far upstream from the ocean.
Bull sharks have a blunt, rounded snout, and a stout, gray back and sides with a light underside. Their name comes from their sturdy appearance and their "pugnacious reputation." They may grow to about 11.5 feet in length and weigh up to about 500 pounds. On average, females are larger than males.
Habitat and Distribution:
As mentioned above, bull sharks prefer shallower waters, and tend to inhabit waters less than 100 feet deep. They have been found in the Mississippi River as far north as Illinois.
Bull sharks usually inhabit warmer tropical and subtropical waters around the world, although they may be found in cooler, temperate waters. In the U.S., they may be found in the Atlantic Ocean from Massachusetts to the Gulf of Mexico and in the Pacific Ocean off the coast of California.
Prey for bull sharks most often includes fish (both bony fish and elasmobranchs). But they may feed on a wide variety of organisms, including crustaceans, sea turtles, cetaceans (such as dolphins), and squid.
Since bull sharks are often in murky water, and they have small eyes, they likely find prey not by eyesight, but by using their lateral line system, hearing, or smell. Because of these factors, they may bite humans more than some other shark species and may easily confuse humans with other prey.
According to the Florida Museum of Natural History, to avoid bull shark attacks, you should not swim near river mouths or in estuaries where bull sharks live, should not swim near schools of fish, be cautious if you are spearfishing, and overall, use common sense when swimming in areas where sharks are known to occur.
Where to See Bull Sharks:
Because of their hardiness, bull sharks are kept in some aquariums - so if you'd like to see one up close with the comfort of a thick glass wall between you and the shark, here are some aquariums where you may see bull sharks (check ahead, as exhibits may change):
Undaunted by the bull shark's fierce reputation? Here are a few places where you can scuba dive with bull sharks (note: obviously, this is an activity that comes with lots of risk. Make sure you have enough experience and pick a reputable company):
The bull shark is listed as near threatened on the IUCN Red List. These sharks may be caught as a game fish, for their meat, fins, or their skin, which is made into leather. Scuba diving with bull sharks is also popular in some areas. Since they inhabit waters close to shore, they may be more affected by coastal development, runoff and pollution than more pelagic shark species.
References and Further Information:
- Bailly, N. 2011. Carcharhinus leucas (Müller & Henle, 1839). In: Nicolas Bailly (2011). FishBase. Accessed through: World Register of Marine Species, January 29, 2012.
- Carpenter, K.E. and Boden, G.E. 2010. Bull Shark. FishBase.org. Accessed January 29, 2012.
- Compagno, L., Dando, M. and S. Fowler. 2005. Sharks of the World. Princeton University Press.
- Crist, R. 2002. Carcharhinus leucas. Animal Diversity Web. Accessed January 29, 2012.
- Curtis, T. Bull Shark. Icthyology at Florida Museum of Natural History. Accessed January 29, 2012.
- Florida Museum of Natural History. 2011. International Shark Attack File. Accessed January 29, 2012.
- NOAA Fisheries. Bull Shark Fact Sheet.
- Simpfendorfer, C. & Burgess, G.H. 2009. Carcharhinus leucas. IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. Downloaded on 29 January 2012.
- Martins, C. and C. Knickle. White Shark (Online). Florida Museum of Natural History Icthyology Department. Accessed September 6, 2009.
- Viegas, J. Largest Great White Shark Don't Outweigh Whales, But They Hold Their Own (Online). Discovery Channel: Discovery Shark Guide. Accessed September 6, 2009.