- Whale Shark Photo
- WCS conservation biologist Dr. Rachel Graham tags a whale shark with a monitoring device that will enable her to track the animal's movements, and help in determining the species' status and needs.
- ©Dan Castellanos
- Whale Shark Photo
- ©Rachel Graham
- Whale Shark Photo
- Julie Larsen Maher ©WCS
Despite its enormous size, the whale shark is a benign creature. This largest living fish is purported to grow up to 65 feet long, but feeds on the smallest of sea creatures—namely, zooplankton, small squid, jellyfish, and sprat. Whale sharks stand out from other sharks due to their checkerboard pattern of pale white spots and stripes stippling a brown background. Each individual has a unique pattern.
Whale sharks live in tropical and subtropical seas, but may make short forays into colder climes. Primarily solitary creatures, they occasionally gather in feeding aggregations that are often segregated according to sex and size. Seasonal aggregations have been sighted in numerous countries including Belize, Cuba, Mexico, the Seychelles, Honduras, Mozambique, Kenya, Djibouti, the Philippines, Australia, and the Maldives amongst others. Feeding groups can reach up to 420 animals in number. Together they feed on seasonal pulses of food, such as thick “soups” of plankton like the copepod blooms off Baja, Mexico or reef fish spawning aggregations in Belize. Often, they undertake large-scale, transoceanic migrations in search of these patches of food.
As viviparous fish, whale sharks give birth to live young, which develop within an egg case in the mother’s uterus. Based on information from one female captured in Taiwan, a mother can carry up to 300 pups at a time and store sperm to fertilize embryos when males may not be present. These pups grow quickly in their first few years of life—more than 3 feet a year—to “outsize” potential predators, including other sharks, orcas, and finfish such as marlin. Humans remain the most effective predator of adult whale sharks.
|Scientific Name||Rhincodon typus|
- Whale sharks are estimated to live 60–100 years.
- Their mouths are up to 5 feet wide and can contain more than 4,000 tiny teeth.
- After their early growth spurts, whale sharks grow slowly, reaching maturity around an estimated 25–30 years of age.
- The smallest free-swimming whale shark measured just over a foot long, and was captured in the Philippines.
- Most cultures where whale sharks are found have special names for them, typically relating to their size and characteristic spots. In Madagascar they are named “marokintana,” meaning “many stars,” and Mexicans call them “domino,” like the game.
Whale sharks are protected in several countries worldwide—including Belize
, Mexico, Honduras, the Maldives, Australia, the Seychelles, India
, and the Philippines. However the highly lucrative Asian shark fin trade and the growing mega-aquarium trade continue to put pressures on their populations, and fishing poses a serious threat to their survival. The animals can get fatally entangled in purse, drift, and gill nets and risk being struck by ships while they bask or feed at the water’s surface. They are targeted by artisanal fishers and occasionally by purse seine netters, primarily in the Indo-Pacific. Although the meat is rarely consumed outside of eastern Asia, whale sharks are increasingly captured for their liver oil, used to waterproof boats and for their fins, which are used as shop signs and status symbols.
Whale sharks are considered Vulnerable to Extinction by the International Union for the Conservation of Nature (IUCN) and are listed on Appendix II of the Convention on the International Trade in Endangered Species of Flora and Fauna (CITES), which helps to regulate their trade. Information on their global population size, highly migratory natures, and seasonal gathering sites is limited, posing challenges to their global conservation.
To determine the status and needs of whale sharks, WCS is studying their environmental and habitat preferences, site residency, and migration pathways as they travel within and between major oceans. We are also examining the tourist industry associated with them. Researchers use an array of tools to study the world’s largest fish: photo-identification, based on the unique pattern of spots that each shark possesses; acoustic tags, which emit pulses of sound picked up underwater by submerged receivers; position-only satellite tags, which transmit the animal’s location when it surfaces; and pop-up tags, which record ambient temperature, depth, and light levels. (Pop-up tags, once detached from an animal, send the data collected via overhead satellite, and eventually, to the researcher by email.) Our researchers and collaborators are using this information to better understand whale shark behavior and to help develop appropriate management and conservation plans.
Shark fisheries have expanded in size and number around the world since the mid-1980s to meet the rapidly rising demand for shark fins, meat, and cartilage. Most of these fisheries are unregulated and undocumented. As a result, numerous shark species now face extinction. WCS is working to improve regulation of the global trade in shark products to reverse the decline of these remarkable fishes.
From the Newsroom
The New York Times interviews WCS's Dr. Rachel Graham about her work in the Gulf and the Caribbean to create a constituency for the protection of a magnificent—and often misunderstood—ocean giant: the shark.
WCS conservationists help Belize develop a management program to restore the health of both fisheries and the coral reef ecosystems at its Glover’s Reef and Port Honduras Marine Reserves.
Dr. Graham, director of WCS’s Gulf and Caribbean sharks and rays program, receives one of the world’s most prestigious prize for grassroots nature conservation. The award recognizes her work to implement a national action plan for sharks and get more local people actively involved in protecting ocean wildlife and coastal biodiversity.