A whale shark encounter is probably one of the things closest to the top of your personal diving “bucket list”, and if you have already been lucky enough to dive with one of these magnificent animals, then it’s likely that you are eagerly anticipating another opportunity to do so again. Let’s head to warm, tropical waters; we’re about to swim with whale sharks.
Whale Shark Facts
Whale sharks inhabit all tropical and warm temperate seas, migrating each spring to the Australia’s central west coast. Primarily pelagic, whale sharks feed seasonally in areas from South Africa to Belize, the Philippines to Zanzibar, and in many other places. Although they are normally found some distance offshore, they are known to enter lagoons and find their way into coral atolls where plankton is abundant. Whale sharks are normally encountered between latitudes of ±30°.
Capable of diving to depths of 1,000 meters, whale sharks are not air-breathing mammals, nor are they related to whales; they were named for their size and for their cartilaginous bodies. Slow moving, Rhincodon Typus is a filter feeder and is the only member of its genus and family. Part of the subclass Elasmobrachii, which includes other sharks, rays, and skates, it is thought to have originated approximately sixty million years ago.
While it was long believed that whale sharks subsisted on plankton and microscopic animals alone, it is now known that they are capable of ingesting tiny fish, along with their eggs and sperm. In addition, they feed on squid and tiny crustaceans.
The largest ever recorded whale shark weighed more than 9 tons and was nearly 12 meters long, although unconfirmed sightings of whale sharks as long as 18 meters have been reported. With light colored undersides and dark brown dorsal sides covered in unique two tone patterns of lines and spots in shades of yellow, whale sharks have skin approximately 10 centimeters thick. No two are exactly alike, which allows researchers to easily identify individuals.
No one has witnessed whale shark mating behavior; however, University of Illinois Chicago scientists were able to study 29 of 304 embryos carried by a female whale shark which was caught off Taiwan’s coast in 1995. The embryos represented an entire spectrum of age and development stages, with some being encased in eggs, and others being nearly fully developed. Paternity was found to be the same for all 29 embryos studied, leading researchers to believe that females mate, then manage to store sperm to fertilize their own eggs as they are produced. While other findings have suggested that whale sharks are not monogamous animals, and while this is an isolated incident, it does point to intriguing possibilities.
Whale sharks give live birth to pups, which are between 16 and 24 inches long at birth. It takes approximately thirty years for these animals to reach sexual maturity; and their life spans are estimated to be between 70 and 100 years. The smallest living whale shark was discovered in the Philippines, with its tail tied to a stake at a beach in Pilar, presumably having been captured by a local fisherman. It was just 15 inches long, and after a short period of study, the creature was released back into the wild. Many of the whale sharks seen at popular dive sites are estimated to be between 15 and 20 years old, which concerns scientists greatly; larger, older sharks are becoming rarer, suggesting that overfishing is taking place.
Diving With Whale Sharks
Encounters with whale sharks occur in many parts of the world, with frequency increasing during specific months. In Thailand, for instance, whale sharks frequent the Phuket area between February and May, and in Belize, between April and August. In Australia, the whale sharks visit Ningaloo Reef between April and July, and in the Galapagos, where an albino whale shark was seen in 2008, they visit from June through November. If you plan to go to a particular area to dive with whale sharks, be sure to find out when the best time to visit tends to be; scientists have begun tracking tagged individuals, so predictions are becoming even more accurate.
Whale sharks often follow or approach dive boats, as if they know that they are about to receive a visit. Once you enter the water with the animals, you may get a close up look at their giant mouths, which hold about 300 tiny teeth so small that they don’t even play a role in feeding. You may see feeding behavior, which sometimes involves swimming forward, or which sometimes takes place in a stationary position. First, the whale shark sucks water into its mouth, then it discharges the water via its gills. Anything larger than 2 or 3 millimeters in diameter is then trapped against the shark’s sieve-like dermal denticles, and is swallowed. On occasion, you may see a whale shark cough; this is normal behavior that scientists believe clears the denticles of food build up.
While diving with whale sharks, and with all creatures for that matter, remember that you are a visitor in the animal’s environment. Try to stay at least ten feet away, and allow the whale shark to control the entire encounter. It may approach you; if this happens, do not touch the animal! Remain quiet.
As you approach a whale shark, move slowly and deliberately so that you are not perceived as a threat. Try to avoid approaching the front quarter of the shark, and avoid flashing lights in its eyes as this can cause it to flee. In addition, stay clear of the shark’s tail. Like other sharks, whale sharks propel themselves by moving their tails from side to side. A powerful tail strike can cause injury.
When diving with a group, avoid surrounding a whale shark; be sure that it has the ability to leave when it wants to. By following these rules, you’ll help the shark feel comfortable with the encounter, and your time together is likely to last longer.
Unfortunately, the world’s biggest fish is on the verge of extinction. Whale sharks are listed as “Vulnerable” by the World Conservation Union, and sightings are beginning to decline. Not only are whale sharks overfished, they are the victims of pollution and poor conservation. Combined with their slow growth rate and low birth rates, their population is incapable of keeping up with man’s greed. For instance, whale shark meat is considered a delicacy in many Asian countries, and a single whale shark fin goes for an exorbitant $15,000 or more. Fortunately, Asian governments are beginning to realize that live whale sharks are worth much more than dead ones; recent studies show that whale shark tourism is worth more than fifty million dollars worldwide, and continues to grow. With strong conservation efforts and better education, we can work to bring whale shark populations back to health.
Comments
I recommend that everyone dive with whale sharks; it is such an amazing experience.