The Great White Shark and Its Migratory Patterns Along the East Coast of the US


The Largest Predatory Fish on Earth

LeapingShark.jpgexternal image insert_table.gif
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Lamniformes
Family: Lamnidae
Genus: Carcharodon
Species: C. carcharias

Average Length: 15 feet
Some been recorded longer than 20 feet and weighing over 5,000 pounds

It should be noted that both the Basking Shark and the Whale Shark are larger
than the Great White Shark, but are not predatory. Instead, they feed on plankton.


great_white_shark.gif
21 ft. Great White Shark beside 6 foot human



Gwsanatomy.jpg
The Great White Shark is distinguished by its torpedo shaped body, gray to blue-gray top half and white underbelly. At any given time, the Great White can have 3,000 teeth. The Great White's teeth continue to grow in rows and replace other teeth when they break off during hunting and feeding. Known for their tremendous sense of smell, the olfactory of the Great White is extremely large and helps the Great White detect one drop of blood in 25 gallons of water.1




Their powerful bodies and tails allow Great Whites to descend to incredible depths, as well as propel themselves completely out of the water to hunt prey when the water is deep enough for them to gain enough speed during their ascent.8


Diet:


The Great White Shark preys upon a variety of fish and marine mammals. The fish the Great White feeds on include but are not limited to Salmon, Halibut, Mackerel, and Tuna. The Great White also feeds on mammals such as harbor porpoises and seals. Because seals are such a large portion of the Great White's diet, the shark's migratory patterns are influenced greatly by the habitats of the seals. The diet of the Great White is also influenced by their age. When they are young, the sharks feed mainly on fish, rays and even other smaller sharks. As they grow older and larger, they begin to feed on marine mammals for the increasing amount of energy their powerful bodies require. While the Great White normally would not feed on the enormous Whale Sharks and whales of the ocean, they are opportunistic feeders that will sometimes act as scavengers, devouring the floating carcasses of dead whales.2





The Marine Mammal Protection Act of 1972:


harborseal
The Marine Mammal Protection Act of 1972 effectively banned the fishing and hunting of all marine mammals. The act was passed by Congress after they decided that, "All species and population stocks of marine mammals are, or may be, in danger of extinction or depletion due to human activities; these mammals should not be permitted to diminish below their optimum sustainable population; measures should be taken immediately to replenish any of these mammals that have diminished below that level, and efforts should be made to protect essential habitats; there is inadequate knowledge of the ecology and population dynamics of these mammals; negotiations should be undertaken immediately to encourage international arrangements for research and conservation of these mammals. As a result of the act, there was a population explosion of one of the Great White Sharks favorite prey, the seal, especially along the shores of Cape Cod and other parts of the Northeastern coast during the summer months.


Reproduction:





Great White Sharks reproduce in what is called a placental viviparity. This means that Great Whites do not have a placenta in the female which helps to assist the development and the nourishment of the babies. At birth, the female can give birth to anywhere from two to fourteen fully developed pups that can measure up to five feet in length. Unlike mammals, Great Whites, like all other sharks, have eggs that are fertilized and then hatch in the womb. The baby shark will eat other unfertilized eggs and its siblings for nourishment. The Great Whites are solitary creatures. Once born, the pups will swim away from their mother and must survive on their own.3





A Great White pup beaches itself and needs to be rescued

Habitat:
migration.jpg
Migratory patterns of a Great White from September to January


The Great White Shark travels in the coastal and offshore waters of the continental shelf. The Atlantic Coast provides the perfect habitat for Great Whites migrating from the warm water off the coast of Florida in the winter to the waters off the coast of Cape Cod and the rest of the Northeast during the summer months. Great Whites can survive from the surface of the water to as deep as 4,240 feet. Presumably to hunt, Great Whites will travel offshore to great depths. Scientists assume that Great Whites must be hunting as the dive would drain so much energy that the shark would need to feed to replace the lost energy. The chance that the Great White could descend to hunt the Giant Squid excites marine biologists. Great Whites live within an ideal temperature range of 59 to 67 degrees. Because of this, the migration of the Great White Shark is determined by, even more than the migration of their prey, water temperatures as the seasons shift.8





Migratory Patterns to Massachusetts:

While it is clear that Great White Sharks migrate to Cape Cod and other locations in the along the Northeastern Atlantic Coast of the United States in an effort to travel within their ideal water temperature range, the presence of seals on Chatham's Monomoy Island also draws the Great Whites closer to shore. Great Whites find themselves in the media in the New England area because they arrive for their annual feeding frenzy just as tourists and locals emerge to enjoy the beautiful Atlantic beaches.

taggedGW
A member of the Cape Cod Shark Hunters watches as a tagged Great White swims off


A group of scientists known as the Cape Cod Shark Hunters describe themselves as a small group of fishermen from Cape Cod that have dedicated our time and efforts into the conservation of sharks in the waters surrounding Cape Cod. They tag several Great Whites each year with pop-up satellite tags that track the migratory patterns along the East Coast. Each year, tags begin to pop up in the waters off the coast of Florida during the winter months indicating that Great Whites can travel great distances driven by changing temperatures and prey.7


Interaction With Humans:

Contrary to the picture that is painted in Hollywood movies such as Jaws, Great Whites are not the mindless killers the media sometimes makes them out to be. In general, Great White Shark attacks are extremely rare. Even when an attack does occur, they are rarely fatal and are usually a case of mistaken identity when humans venture into areas where they can be confused with the Great White's natural prey. Great Whites are curious creatures that will bump, and sometimes bite, in order to investigate their surroundings. Attacks are rarely fatal due to the fact that Great White's desire a prey that is much higher in fat than humans, such as in the blubber of whales and seals. Because Great Whites are so rare, they are a protected species that is threatened by commercial fishing and media-led "witch hunts" following an attack(s). Because Great White females do not reach sexual maturity until 12 to 15 years old, the species takes a long time to reproduce. Therefore, it is vital that the Great Whites are protected so their numbers can continue to rise. As apex predators, they are an integral part of the entire oceanic ecosystem.9




Sources:

1. http://www.elasmo-research.org/education/white_shark/structure_brain.htm
2. http://www.ucmp.berkeley.edu/vertebrates/Doug/shark.html
3. http://www.enchantedlearning.com/subjects/sharks/species/Greatwhite.shtml
4. http://www.bbc.co.uk/nature/life/Great_white_shark
5. http://news.stanford.edu/news/2002/january9/sharks-19.html
6. http://www.shark-tracker.com/en/Great-White-Shark/Profile/index.php
7. http://www.capecodsharkhunters.com/default.html
8. http://www.great-white-shark.com/shark-habitat.html
9. http://www.whitesharktrust.org/pages/index.html