August 30th is International Whale Shark Day

30 August is dedicated to the world’s largest fish, the whale shark, in an effort to raise awareness of this animal’s vulnerable conservation status.

The whale shark, Rhincodon typus, can grow to a length of approximately 12 m and weigh as much as 21 metric tons. A filter feeder, it preys mainly on microscopic plankton – although it has been documented feeding on larger fish in some instances. The species’ range extends to tropical seas around the globe, but populations in many areas have historically been depleted by fishing. Other threats include pollution, depletion of prey and habitat through overfishing, collision with boats and the continued demand for whale shark fins in Chinese medicine.

Despite its large size, little is known about the life history of the whale shark. Mating and birthing behaviors have never been observed in the wild, although the species is believed to be ovoviviparous – incubating eggs internally before giving birth to live young. Even the maximal size of adult sharks is unknown, with some unconfirmed sightings indicating that lengths of 14 m or more are possible.

In addition to being the largest non-mammal vertebrate and the only member of the Rhincodon genus, the whale shark also holds a cultural and social significance. In Vietnam, the shark is considered to be a deity, and is referred to as ‘Ca Ong’ (‘Sir Fish’). In Kenya, it is known as ‘Papa Shillingi’, in reference to the myth that God threw shillings onto the fish’s back, creating its spots. In many countries, including Mexico, the fish is also the basis of profitable ecotourism, which encourages more sustainable use of natural resources.