Whale shark, where it lives and conservation

The IUCN Red List classifies it as endangered.

by Lorenzo Ciotti
Whale shark, where it lives and conservation

The Whale Shark inhabits all the tropical and temperate seas of the Earth with water temperatures not lower than 21 °C. This fish is primarily pelagic and can be found in both coastal and oceanic habitats living in the open ocean but not in the greater depths of the ocean, although it has been known to occasionally dive to depths of up to 6,200 feet.

It is migratory and has two distinct subpopulations: an Atlantic subpopulation, from Maine and the Azores to Cape Agulhas, South Africa, and an Indo-Pacific subpopulation which holds 75% of the entire whale shark population.

It usually wanders between 30°N and 35°S where water temperatures are above 70°F (21°C), but has been sighted as far north as the Bay of Fundy, Canada and the Sea of Okhotsk, Al northern Japan and as far south as Victoria (Australia).

Seasonal feeding aggregations occur in several coastal sites such as the Persian Gulf and the Gulf of Oman, the Ningaloo Coast in Western Australia, Darwin Island in the Galápagos, Quintana Roo in Mexico, the province of Inhambane in Mozambique, in the Philippines, around Mahe in the Seychelles, the coasts of India of Gujarat and Kerala, Taiwan, South China and Qatar.

In 2011, more than 400 whale sharks gathered off the coast of Yucatán. It was one of the largest recorded whale shark gatherings. Aggregations in that area are among the most reliable known seasonal gatherings for whale sharks, with large numbers occurring between May and September most years.

The associated ecotourism has grown rapidly to unsustainable levels. Whale sharks are known to prey on a range of planktonic and small nektonic organisms that are spatiotemporally patchy. These include: krill, crab larvae, jellyfish, sardines, anchovies, mackerel, small tuna and squid.

In ram filter feeding, the fish swim forward at a constant speed with their mouths wide open, filtering prey particles from the water by forward propulsion. This is also called passive feeding, which usually occurs when prey is present in low densities.

Because of their feeding pattern, whale sharks are susceptible to ingesting microplastics. As such, the presence of microplastics in the stomach of whale sharks has recently been confirmed. The shark is seen by divers in many places including: the Bay Islands in Honduras, Thailand, Indonesia, Philippines, Maldives, Red Sea, Western Australia, Taiwan, Panama, Belize, Mozambique, South Africa, Galapagos Islands, Sant' Elena, La Paz, Baja California Sur and Bahía de los Ángeles in Mexico, Seychelles, West Malaysia, islands off Peninsular East Malaysia, India, Sri Lanka, Oman, Fujairah, Puerto Rico and other parts of the Caribbean.

Juveniles can be found near the coast in the Gulf of Tadjoura near Djibouti in the Horn of Africa. The whale shark is a fish that is still caught today in some countries where it is eaten both raw and cooked, for food (fins, meat), industrial (liver oil) and popular (it is an ingredient in traditional Chinese medicine).

The IUCN Red List classifies it as endangered. In 1982 the UN commission on the sea classified it as a migratory species in need of scientific studies to understand its risk of extinction. In 1999 the Bonn Convention on migratory species considers it a species with an unfavorable conservation condition and since 2003 attempts have been made to diplomatically prohibit its trade in countries that hunt and consume whale sharks.

Since 2005, three specimens have been housed in captivity in the Churaumi Aquarium in Okinawa (Japan) while a pair is housed in the Georgia Aquarium in Atlanta.