The whale shark is the largest fish in the sea, they can reach lengths of 40 feet or more, and can live for over 100 years. They are filter feeders, scooping tiny creatures including plankton, crustaceans and small fish with their colossal gaping mouths while swimming close to the water's surface. Their food becomes trapped in the shark’s dermal denticles whilst filtration takes place. The whale shark can filter more than 1,400 gallons of ocean water per hour.
As a pelagic species, the whale shark inhabits open sea areas, as opposed to other shark species who dwell near the ocean floor. They are known to gather at a dozen major feeding locations around the world, from western Australia and Indonesia to Belize. But between May and September, the waters of Mexico's Quintana Roo state, on the north-eastern Yucaton Peninsular, draw far more animals than other spots and attract an estimated 800 or more in each season.
Whale sharks have been relatively understudied by scientists. This is primarily because despite being the largest non-mammalian vertebrate alive, these majestic animals are actually very secretive. Whale sharks were first discovered in 1828, but it wasn’t until the 1980’s that scientists realised they could reliably be spotted at various feeding sites. However, it tends to only be juveniles or adult male sharks at these spots, and the females and babies remain elusive.
Whale sharks may have an internal sat-nav
Scientists have recently found that Darwin Island in the Galapagos, appears to attract very large whale sharks and pregnant females. Unfortunately, these sites are hard to get to, and so a lot remains unknown about these animals, particularly why they pass through Darwin, as it is not a feeding ground. One theory is that they are calibrating their internal GPS system.
Volcanic eruptions at Darwin have created magnetically polarised rock on the seafloor. This can provide a relief map for animals who are able to detect the Earth’s magnetic field. Scientists think that whale sharks may be attracted to Darwin island as they can use this magnetic map to position themselves. The whale sharks will often dive extreme depths in this area too, and these dives coincide with the Earth’s varied magnetic intensity which fluctuates on a daily cycle. Scientists think that the sharks may be performing these deep dives to get a more accurate idea of their location.
Whale sharks give birth to live young
Whale sharks are particularly unique in that they give birth to about 300 live young. Like other sharks, they produce eggs, but the female whale shark keeps the fertilised eggs safely in her abdomen until they hatch. She then gives birth to the live young.
Just look at their spots
Whale sharks are covered in white spots. The patterns are as unique to individual whale sharks as fingerprints are to humans. Whale shark researchers use specialised computer software to identify individuals from their spot patterns. This software, which was originally developed for star constellations, can compare pictures of whale sharks to help scientists identify and track individuals.
Whale sharks really are amazing animals
Whale shark conservation
Whale sharks are classed as endangered on the IUCN Red List and are at risk of becoming extinct if things do not change. Sadly, these amazing animals have been the victim of the shark finning trade, where they are hunted for their valuable fins. Overfishing from this trade has caused a significant decline in whale shark numbers. There is also a high demand for whale shark meat and oil, and although illegal, they are still caught by illegal fisheries.
Thanks to an increase in tourism, the trade in shark fins and meat is declining, as these animals are more profitable alive than dead. However, there is still an active trade which remains a considerable risk to their conservation status. Whale sharks may also be caught up in fishing nets by mistake as by-catch, which is often fatal.
More recently, whale shark tourism has dramatically increased, resulting in high numbers of humans swimming with these graceful creatures in their natural habitat. If done correctly, this can benefit the conservation status of the fish, however several operators see the activity as a profit maker, interrupting the whale sharks feeding process to entertain tourists. There have also been cases of boat/propeller injuries within this industry, as the whale sharks collide with the boats, causing serious and often fatal injuries.
Whale sharks, like many ocean species are also in danger from the ingestion of microplastics in the sea. Microplastics are small pieces of plastic less than 5mm in size. Some microplastics are manufactured, such as the microbeads added to health and beauty products, whilst others are the result of larger plastics gradually breaking down. These plastics are pervasive in marine environments, and they are known to harbour toxic substances such as heavy metals and phthalates.
How can we help the Whale Shark?
There is still much more we can learn about these elusive animals. The main way we can help the whale shark is by using scientists to discover more information regarding their life cycles, habitats and overall behaviour. This information can allow specific conservation plans to be put in place and allocate areas to be protected. The more we know, the more we can do!
The shark finning trade is slowly decreasing, which is good news for all shark species. However, illegal fishing does still occur, meaning campaigning against this trade is essential in ensuring a growing whale shark population.
If visiting or taking part in a whale shark diving activity, make sure the operator is a trusted and sustainable company. Most conservation focused providers make this clear prior to your dive!
Conservation of these far-roaming animals will take international cooperation because whale sharks spotted in one area may depend, in other seasons, on resources located many hundreds of miles away.
For more details see;
Whale Shark Research Project
Whale sharks in captivity:
Many whale sharks are now being ripped from the wild to supply the ocean park industry, where they must adapt to an artificial diet and habitat, excessive noise and the proximity of people and unknown animals, and deal with the adverse impacts of swimming within chemically treated waters. Many suffer from the stress of confinement, often resulting in illness and premature death. Whale sharks are wide-ranging animals with diverse physical, behavioural and psychological needs. Keeping whale sharks in captivity causes them to suffer unnecessarily. Whale sharks can live up to 150 years, and so a life in captivity is cruel and long.
For details of the captive industry in China seehttp://chinacetaceanalliance.org/en/china-cetacean-alliance/