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Do sharks migrate?

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Scalloped hammerheads swarm in a massive migration each year at the Galapagos Islands. Credit: Kladivoun Bronzový Galapágy.

By Blaise Jones

Sharks are a highly migratory species. While there are a few exceptions, sharks do not stay in one place for long. They’re always on the move looking for new sources of food. However, not all shark movement is simple meandering. Sometimes sharks go to places in large groups for very specific purposes, which is called a migration.

Have Fins, Will Travel

While some species of shark don’t travel all that far, such as the bonnethead shark and the bull shark, others are prodigious travelers. The bigeye thresher shark has been recorded migrating from New York to the Gulf of Mexico, covering 1,719 miles (2,767 km). Sandbar sharks routinely travel between the northeastern United States and the Yucatan Peninsula in Mexico, a trip of 3,480 miles (5,600 km).

However, both of these long distance travelers pale in comparison to the migration king. Female blue sharks will go to great lengths to have their offspring. During a mating season a single female blue shark, from conception of her pups to their birth, will travel as much as 10,000 miles (16,000km).

Just like the blue shark, sharks always migrate with a reason in mind.

Tis the Season

Like most migratory animals, sharks follow a seasonal migration pattern. During the summer months the cold, nutrient-rich, waters of the northern polar seas experience large plankton blooms. This causes a mass influx of smaller animals that eat the plankton, and are in turn eaten by larger predatory animals, including sharks.

As the summer comes to an end the plankton stops blooming, and the abundant food sources that sustained these migratory predators fades away. Once fall hits and the northern polar waters turn colder, the sharks begin their migration back to more tropical and temperate climes, where there might be less food, but it is a lot warmer.

Migratory Mating

Besides feeding, the other main reason shark migrate is to breed. Some species of shark are s regular in their mating migrations that entire tourist industries revolve around them. Scalloped hammerhead sharks congregate in huge numbers off the Galapagos Islands in order to breed and each year thousands of scuba divers come to see the huge schools of shark.

Sandbar sharks travel to Florida during the spring months to mate and then travel up north to give birth in estuaries. The pups will spend the summer maturing and then by winter they will be big enough to migrate down south for the winter.

This map of the Pacific Ocean shows the migratory route that great white sharks take from California to Hawaii. The large mass in between the two is the region known as Shark Cafe, where great white sharks gather by the thousands. Credit: NOAA.

The Shark Café

Perhaps the most mysterious and elusive migratory shark is the great white. Extensive research has been done on the migratory patterns of great whites, so much so that we now know that there are two distinct populations of great white sharks in the world. One migrates between South Africa and Australia, and the other migrates between Hawaii and California. However, this second population of sharks makes an unusual pitstop.

What is now known as The Shark Café is a desolate strip of the Pacific Ocean in the middle of great white shark migration paths. What makes this empty stretch of ocean noteworthy is that for some reason great white sharks gather here. There is no food to be found, and great whites are a coastal dwelling species, so it is unknown why exactly they gather here. What is known is that there are some very odd behaviors put on display in this area.

The male great whites will routinely dive down to depths of as deep as 3,000 feet, doing so as often as 150 times a day. The exact purpose of this bizarre behavior is unknown, though it is speculated that it is a type of mating display. At this time we just don’t know enough to make any assumptions.

However, as time goes on and technology gets better, easier to use, and cheaper still maybe we will one day solve the mystery behind The Shark Café.

SOURCES:

“Sharks: The Animal Answer Guide” by Gene Helfman and George H. Burgess

“The Encyclopedia of Sharks” by Steve Parker

http://www.natureworldnews.com/articles/24768/20160706/look-great-white-shark-camera-reveals-strange-journey-cafe.htm

http://www.nwf.org/news-and-magazines/national-wildlife/animals/archives/2014/blacktipped-sharks.aspx

http://oceanofk.org/tag/Tagmigrate/cfactorscause.html

-TSF-

#sharks #migration #bluesharks #greatwhite #SharkCafe #TSF

 
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