Whale Shark
- Whale Shark Photo
- Julie Larsen Maher ©WCS
Among the often-fearsome sharks, the whale shark is comparatively benign. It is the largest living fish, growing up to 65 feet long, but feeds on the smallest of sea creatures—namely, zooplankton, small squid, jellyfish, and sprat plankton. Whale sharks stand out from their other big-jawed kin with their distinctive markings, a checkerboard pattern of pale yellow spots and stripes that is unique to each individual.
Whale sharks live in tropical and warm oceans. Primarily solitary creatures, they occasionally gather in all-male or all-female groups that are often segregated according to size and age. Seasonal aggregations have been sighted offshore in Belize, Mexico, the Seychelles, Honduras, Mozambique, Kenya, Djibouti, the Philippines, Australia, and the Maldives. These groups can reach 400 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 ovoviviparous fish, whale sharks give birth to live young, which develop within an egg case in the mother’s uterus. Mothers can carry up to 300 pups at a time. 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.
Fast Facts
| 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 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.
|
Challenges
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. Captured for their meat, known as tofu-shark in Taiwan, they are also sought after for their liver oil and fins. Elsewhere in Asia, their fins are used as shop signs and status symbols.
Whale sharks are considered Vulnerable to Extinction by IUCN. Information on their global population size, highly migratory natures, and seasonal gathering sites is scarce, posing a great challenge to their conservation.
WCS Responds
To determine the status and needs of whale sharks, WCS is studying their environmental and habitat preferences, site preferences, and movements. Researchers use acoustic tags, which emit pulses of sound picked up underwater by submerged receivers; satellite tags, which transmit the animal’s location when it surfaces; and pop-up tags, which record ambient temperature, depth, and light levels and send this data via overhead satellite, and eventually, to the researcher by email. These tools enable WCS scientists to determine the animals’ environmental preferences and both their horizontal and vertical movements, day and night and seasonally. Our researchers are using this information to better understand whale shark behavior and to help develop appropriate conservation plans.
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.