Annual Whale Shark Swarm Offers Unique Opportunity to Study the Mysterious Species

whale sharks photo

Photo credit: Proyecto Domino

Once every year, the world's largest and most mysterious fish gathers in swarms in the warm waters off the coast of the Yucatan Peninsula. The typically elusive whale sharks come in search of plankton, which blooms here in early spring thanks to an upwelling of colder water.

Called the "afuera," because it occurs outside Mexico's designated whale shark preservation zone, the event provides a unique opportunity for scientists to study the poorly-understood species.

whale shark mouth photo

Photo credit: Christian Steen/Creative Commons

Using satellite tags, scientists have determined that whale sharks travel astonishing distances. One tagged female covered more than 4,500 miles in 150 days and others have been measured at 6,325 feet, well over a mile beneath the ocean's surface.

WATCH VIDEO: Today on Planet 100: Top 5 Endangered Sharks

Still, there remains much that scientists don't know about the whale shark. Mating, in particular, is a mystery. Jennifer Schmidt, a biologist at the University of Illinois at Chicago, commented that:

The genetics tell us that there seems to be a large degree of migration and interbreeding between animals around the world...there must be a place where adult males and females meet to breed, but we don't know where that place is.

It's not, at any rate, in the Yucatan. The populations that gather are predominately adolescent males.

whale shark swimming photo

Photo credit: quinn.anya/Creative Commons

Though it has not produced any clues on mating, the afuera has helped scientists understand whale shark eating habits. Like true whales, whale sharks are filter feeders. They skim across the surface of the ocean, separating plankton and small fish from gallons and gallons of water.

It is this feeding pattern, scientists say, that makes whale sharks particularly vulnerable to ocean pollution—like the droplets of oil suspended in the waters of the Northern Gulf.

Read more about whale sharks:
Ocean Film Fest 2010: Whale Sharks By The Hundreds at Isla Holbox
Free Sammy! Whale Shark in Dubai Aquarium Should Be Freed
UN Agreement Protects Seven Migratory Shark Species, But Australia Opts Out (Partially)

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