Every August 30th, International Whale Shark Day is celebrated, a date dedicated to highlighting the largest fish on the planet . Despite its imposing size, this animal is completely harmless to humans and feeds mainly on plankton and small organisms that it catches by filtering water.
In the following lines we review the most striking curiosities of this species , the threats that put its survival at risk and the initiatives that seek to guarantee its future in the oceans.
Amazing characteristics of the world's largest fish
The whale shark (Rhincodon typus) It reaches lengths of up to 20 meters and a weight of 42 tons.Although the most common length is around 12 meters, it is not a whale, but a cartilaginous fish with a cartilage skeleton like that of sharks. It feeds by opening its enormous mouth, which can exceed one meter in width, and swallowing large volumes of water from which it filters plankton, krill, and eggs. de peces and small crustaceans. Its throat is so narrow that it cannot swallow large prey.
One of its most striking features is its skin, with a pattern of light spots and lines on a dark background. Each specimen has a unique design, like a fingerprint , allowing scientists to identify them without marking them. It is also a tireless migrant: it travels thousands of kilometers a year, and it has been documented diving to depths of almost 2.000 meters, a record for any fish. To withstand the low temperatures, it has skin up to 30 centimeters thick.
As for its life cycle, it is estimated that it can live between 130 and 150 years, although its growth is very slow. Its reproduction has been a mystery for decades : only one confirmed pregnancy has been recorded, that of a female in Taiwan carrying 304 offspring. This giant also plays an essential ecological role by controlling plankton populations and providing refuge for smaller fish that feed on its parasites.
Threats and efforts to protect the whale shark
Despite its size, the whale shark is listed as an endangered species on the IUCN Red List, with a declining population trend. Among the main threats are bycatch in fishing nets, the illegal wildlife trade , plastic pollution, collisions with vessels, and unregulated tourism that can disrupt its feeding grounds. According to the Marine Megafauna Foundation, more than half of the global population has disappeared since the 80s.
To halt their decline, several initiatives have been launched. In Tanzania, for example, the population on Mafia Island increased from approximately 100 individuals in 2012 to 206 in 2019 thanks to conservation efforts. In the Philippines, 29 individuals have been fitted with satellite tags to track their movements, and in Mexico, tourists and tour operators are being trained to reduce dangerous encounters related to tourism . Furthermore, it is recommended that sightings be conducted from authorized vessels, at a distance, and without flash photography to avoid stressing the animals.
Conserving the whale shark benefits not only the species itself, but the entire marine ecosystem. By protecting this giant, we also contribute to the health of the oceans, and therefore to the health of all the species that depend on them. This international day aims to remind us that our everyday choices, such as reducing plastic use or choosing sustainable fish, have a direct impact on their survival. With coordinated efforts, it is possible for this colossus of the sea to continue roaming the waters for many years to come.
