International Whale Shark Day Date in the current year: August 30, 2024

The whale shark is the largest known extant shark, the largest known extant fish species, and the largest living nonmammalian vertebrate. It can reach a length of around 48 ft (14.5 m); the largest confirmed individual had a length of 62 ft (18.8 m), but some studies have suggested that whale sharks can reach a length of 72 ft (21.9 m).

Despite its size, the whale shark is absolutely harmless to humans. Whale sharks are slow-moving and feed on plankton, like baleen whales, and sometimes small shoaling and schooling fish (anchovies, sardines, small mackerels, etc.). In fact, the whale shark was named after baleen whales due to its size and to its being a filter-feeding species.

Whale sharks live in tropical waters throughout the world ocean, preferring warm water above 70 °F (21 °C). They have two distinct subpopulations: an Indo-Pacific subpopulation, holding three quarters of the entire whale shark population, and an Atlantic subpopulation. The whale shark is migratory, migrating to target seasonal concentrations of plankton and forage fish.

Although the whale shark is primarily pelargic, e. g. prefers to stay near the surface, it remained unknown to science for a long time. Even today very little is known about its behavior and reproduction. It is so different from other sharks that scientists have it classified as the sole member of the genus Rhincodon and the only extant member of the family Rhincodontidae.

The total number of whale sharks is unclear. According to some reports, there are only about a thousand of them left, although some sources report that this number includes only specific individuals that have been sighted by scientists, and the actual number of whale sharks is higher. Be that as it may, the whale shark is classified as an endangered species.

The decline of the population of whale sharks, which amounts to 5–6% per year, is mainly caused by whale shark fishing in South and Southeast Asia, where whale sharks are fished for human consumption. Although most countries have banned fishing, selling, import, and export of whale sharks, illegal fishing is still a problem in some countries.

The population of whale sharks is recovering slowly due to their slow rate of reproduction and late sexual maturity. According to different estimates, whale sharks reach the age of maturity at 30, 35 or even 50. In addition, young whale sharks, which have practically no means of self-defense, can fall prey to blue sharks, blue marlins, or killer whales (adult sharks are protected from predators due to their size and thick skin).

International Whale Shark Day was created in 2012 to raise awareness of this endangered species (although back then the whale shark was classified as vulnerable). It is observed on August 30 by conservation organizations across the world. International Whale Shark Day is marked by various events and awareness campaigns focusing on these incredible animals.