Eight Facts About the Whale Shark

It’s International Whale Shark Day! The day for the world to celebrate one of its most remarkable creatures – the whale shark. To get you in the spirit, here are eight facts about the largest fish in the sea and what’s being done to help conserve these beautiful creatures.

1. Whale sharks are second in size only to actual whales – they weigh over 20 tons and can measure over 12 meters in length. Some unconfirmed accounts even claim sightings of sharks over 17 meters! A hefty figure isn’t the only thing whale sharks have in common with their namesake however, because just like a whale…

2. Whale sharks filter feed. They do not use teeth to catch prey, instead slowly drifting through the water holding their mouths wide to suck in plankton and small fish. Modified gills sort out the loot. Whale sharks are one of only three known sharks in the world that feed in this way, along with the basking shark and the mysterious megamouth shark, and all three evolved this trait independently. How very enterprising!

Whale Shark Image courtesy of Flikr user KAZ2.0

Whale Shark Image courtesy of Flikr user KAZ2.0

3. Each whale shark has a unique pattern of spots, which acts like a human fingerprint. These spots are crucial for identifying whale sharks and keeping tabs on the population size. The WWF alone has studied 458 individual whale sharks using this technique. And getting an idea of whale shark population sizes is important because…

4. In July, the whale shark was reclassified from Vulnerable to Endangered on the International Union for Conservation of Nature (IUCN) Red List. This move was informed by an increased amount of data on the whale shark in the ten years since its status was last assessed. Estimates now show that whale shark populations have declined by over 50% globally and 75% in the Indo-Pacific alone over the past three whale shark generations (about 75 years). This decline has been brought about by the major threats to whale sharks, which brings us to Fact Number Five:

5. Though the whale shark trade is supposedly regulated by the Convention on International Trade in Endangered Species (CITES) and fishing for whale sharks is banned in countries like the US, they are still heavily targeted by fisheries in Southern China and are frequently caught as by-catch in purse seine and gillnet fisheries. This is a troubling state of affairs, and has already done serious damage to the population, but hope is not lost. There are things you can do to help! For instance…

6. Whale shark conservation benefits immensely from ecotourism. In fact, whale sharks are doing unusually well in the Gulf of Mexico because they are worth much more to local communities alive than dead. This means that helping whale sharks can be achieved just by paying to go hang out with these gentle giants – neat!

Image by Feefiona123 (http://creativecommons.org/licenses/by-sa/4.0), via Wikimedia Commons

Image by Feefiona123 (http://creativecommons.org/licenses/by-sa/4.0), via Wikimedia Commons

7. You can also give whale sharks a helping hand by making sure you only eat sustainable seafood. For instance, tuna fisheries have high levels of whale shark bycatch and many other types of fisheries target the highly productive areas of the ocean where whale sharks like to feed. When possible, buy hook and line caught fish or look for fish caught by smaller inshore vessels.

8. The IUCN itself is doing its share to protect this newly Endangered shark. On September 1, the IUCN Conservation Congress in Hawaii will kick off, and two of the six key topics to be discussed (protected areas and increased ocean governance) could directly benefit the whale shark. Check out the links below to learn more about the whale shark and the upcoming Conservation Congress!

Image by Zac Wolf (http://creativecommons.org/licenses/by-sa/2.5), via Wikimedia Commons

Image by Zac Wolf (http://creativecommons.org/licenses/by-sa/2.5), via Wikimedia Commons

Resources to learn more

The updated IUCN Red List page on whale sharks:


Video explaining the rationale for the Red List status change:


National Geographic Article about the way forward for whale shark conservation:


Information about the IUCN World Conservation Congress


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