Researchers Reveal Whale Sharks' Secrets

September 29, 2005

Release from: Matt Saindon
Babson Free Press (Massachusetts)

By attaching hi-tech electronic tags to the world's largest fish, whale sharks, researchers now know how and where they find their food. This new data and knowledge regarding the whale shark's behavior helps authorities adjust conservation policies because these gigantic fish are listed as being vulnerable to extinction. Researchers in Belize have tracked the sharks as they dive almost half a mile in search of food, including shoals of spawning fish so they can eat the offspring.

The whale sharks grow to a length of over 65 feet.

According to researchers, their findings will also help those better plan tourism operations around the whale sharks in such a way that does not harm the creatures in any possible manner. These new and unparalleled insights into the whale sharks' world come from the world's second largest barrier reef system and a site given United Nations World Heritage status, the Belize Barrier Reef.

Rachel Graham of the Wildlife Conservation Society for the United States says that the study has showed that whale sharks dive much deeper than previously alleged. They reach depths of over 3,200 feet in search of food. The water at this depth is only a few degrees above freezing, and consequently, scientists finally understand why whale sharks have an insulating fat layer right below their skins.

Whale sharks typically remain in shallow water during the night while feeding off plankton and reserving deep dives for the heat of the day. In order to give their bodies a burst of oxygen after swimming in an area having much less oxygenated water, the whale sharks often end the deep dive with a high speed ascent.

Every time there is a full moon, whale sharks have a big feast of snapper caviar because Cubera snappers come together and generate offspring. Scientists can attach the electronic tags to the whale sharks when they surface for their feast. The tags make normal recordings of temperature, water pressure and light level, and after a pre-programmed period, they routinely detach from the shark, float to the surface, and beam their data back to the researchers as an e-mail through a satellite. Whale sharks are found around the world in open water and near the shores. Although they are the world's largest fish, they would rather eat plankton than people. Their slow movements make them easy to catch by harpoon or net.

IUCN, the World Conservation Union, lists the whale shark as being vulnerable on its Red List of threatened species. Under the Convention on International Trade in Endangered Species, trading a whale shark's fins is now regulated. In Belize, the gigantic creatures are now even used as tourist attractions. It is very important for Belize to protect the feeding sites and habitat of the whale sharks when they visit, so they can help sustain the number of sharks in the wild.