The whale shark (Rhincodon typus) is a slow-moving filter feeding shark and the largest known, still surviving, fish species. The largest confirmed individual had a length of 12.65 m (41.5 ft) and a weight of about 21.5 t (47,000 lb).
It is the sole member of the genus Rhincodon and the family, Rhincodontidae (called Rhiniodon and Rhinodontidae before 1984), which belongs to the subclass Elasmobranchii in the class Chondrichthyes. The species originated about 60 million years ago.
The whale shark is found in open waters of the tropical oceans and is rarely found in water below 22 °C (72 °F). Modelling suggests a lifespan of about 70 years, but measurements have proven difficult. They have very large mouths and are filter feeders, which is a feeding mode that occurs in only two other sharks, the mega mouth shark and the basking shark. They feed almost exclusively on plankton and, therefore, are completely harmless to humans.
The species was distinguished in April 1828 after the harpooning of a 4.6 m (15 ft) specimen in Table Bay. The name “whale shark” comes from the fish’s size, being as large as some species of whales and also that it is a filter feeder like baleen whales.
The whale shark inhabits all tropical and warm-temperate seas. The fish is primarily pelagic, living in the open sea but not in the greater depths of the ocean. Seasonal feeding aggregations occur at several coastal sites such as the southern and eastern parts of South Africa; Off Tofo Reef near Inhambane in Mozambique; Although typically seen offshore, it has been found closer to land, entering lagoons or coral atolls, and near the mouths of estuaries and rivers. Its range is generally restricted to about 30° latitude
Whale sharks have a mouth that can be 1.5 m (4.9 ft) wide, containing 300 to 350 rows of tiny teeth and 10 filter pads which it uses to filter feed. Whale sharks have five large pairs of gills. The head is wide and flat with two small eyes at the front. Whale sharks are grey with a white belly. Their skin is marked with pale yellow spots and stripes, which are unique to each individual. The whale shark has three prominent ridges along its sides. Its skin can be up to 10 cm (3.9 in) thick. The shark has a pair of dorsal fins and pectoral fins. Juveniles’ tails have a larger upper fin than lower fin, while the adult tail becomes semi lunate
The east coast of Southern Africa is blessed with a very healthy population of “Rhincodon typus” or Whale Shark, for now! Unfortunately, these gentle giants are being mercilessly fished by the local fishermen along the entire east coast of Africa.
Whale Sharks are highly efficient filter feeders favouring the warmer waters of the oceans following seasonal concentrations of food. Off the coast of southern Africa, their range extends from the sub-tropical waters of KwaZulu/Natal, north to the equator, and beyond. Being warm water animals, in South Africa they are seasonal, and are found mainly off the KwaZulu/Natal north coast, but only during the summer months, (November through March), when the water temperatures reach a maximum of about 28º C. However, off the cost of Mozambique, which lies mainly in the tropics, they are found year round.
So, in reality, as for encountering Whale Sharks off the coast of KZN, your chances are slim! Please do not bank on seeing them at all, even if you go out daily. Divers at Sodwana “occasionally” see them on their way out to the reef for a dive, or on their way back to shore, after a dive, buts that a very lucky and special sighting.
Off the cost of Mozambique, the concentrations of Whale Sharks are the greatest north of Xai Xai. Here you are likely to find Whale Sharks all year round, with greatest concentrations in the summer months when the waters are at their warmest.
The best way to interact with these giants of the ocean is to “cruise” the back-line just beyond the breakers in a boat. The tell-tail sign that there is a whale Shark in the water is the tip of their caudal fin breaking the surface of the water. Because the boats that we use off the coast of Southern Africa are mainly “Rubber Ducks” or Zodiac’s we are positioned very low in the water so it is not possible to spot the animal’s great hulk from above. The other way in which to spot them is from a micro-light aircraft, but this is very expensive as there are no micro-lights based anywhere along the coast of Mozambique, so the plane and pilot would have to be “imported”.
Divers wanting a Whale Shark experience are normally based at a dive resort along the cost of Mozambique, either at a resort close to the town of Inhambane, on one of the islands of the Bazaruto Archipelago or at Pemba in the north of the country. The Whale Sharks are usually encountered on the boat ride out to the dive site, and on the return trip back to shore after the dive. The distance from the shore to the reefs is anything from a few hundred meters to 25 km’s out to sea, so the chances of “bumping” into a Whale Sharks is very good when on your way to and from a dive.
As soon as the caudal fin of the Whale Shark is spotted the skipper of the “duck” (Zodiac or RIB) positions the boat in the path of the oncoming Whale Shark and the divers bail overboard, as quickly and quietly as possible, and wait for the Whale Shark to swim up to them. The amount of time that the divers are able to interact with the Whale Shark can be anything from a few seconds to 15 minutes and longer, depending on the individual animal. Experience has shown that it’s best to interact with the Whale Sharks when on snorkel and not on scuba as the exhaust bubbles from the regulator often frightens the Whale Sharks away.
For the non-scuba diver wanting the experience of being able to interact with Whale Sharks, you are able to charter a “Rubber Duck” purely for this purpose, and you spend as many hours as you like, or can afford, cruising the back-line, just beyond the breakers, looking for, and when found, interacting with the animals. The “Duck’s” are chartered out on an hourly bases, just as they would be for divers going on a dive or for deep-sea fishermen going out for a day’s fishing.
To be able to get to any of the main locations in Mozambique, either, Inhambane, the Bazaruto Archipelago or Pemba is to fly. Flights depart out of Johannesburg International but to Inhambane and to Pemba, these flights only operate on certain days of the week, unlike flights to Bazaruto which operate daily.
Divers must also please remember that Whale Sharks are animals in the wild, who have the whole world’s oceans as their “back yard”. They are extremely sensitive to water temperature, ocean currents, wind and most importantly, the availability of zooplankton, which is their main source of food. Having said that, you must appreciate that although the east coast of Southern Africa has a large and currently healthy population of Whale Sharks it is impossible to guarantee sightings of these gentle giants of the ocean. Obviously, the more time you are able to spend on the water looking for the Whale Shark, the better your chances are of interacting with them.
Whale Sharks are also protected species in the waters of Mozambique with the result any diver, snorkeler or swimmer want to go out and interact with Whale Sharks will be required to sign a “Code of Conduct” (attached) which specifies the “Do’s and Don’ts” when diving and interacting with Whale Sharks. As you will see from this code of conduct, it is forbidden to touch and hang on to these animals. Please be advised of this, as this code of conduct is strictly enforced and is there for the protection of these wonderful animals.
Also, when diving anywhere in South Africa or Mozambique, please don’t expect to do more than 2 dives a day. By noon, along the entire east coast of southern Africa the wind tends to pick up quite a bit, causing white caps on the ocean and making diving conditions difficult and even dangerous. As all dives are drift dives, it’s very difficult for the skipper of the Rubber Duck to spot the buoy in rough conditions and even more difficult to spot individual divers as they surface after their dive. The first dive of the day is usually scheduled for sunrise with the second dive of the day being scheduled after surface interval time and breakfast, at about 10h30. By noon, when the wind has picked up, all dives for the day have been completed. If by chance there is no wind, then a 3rd or even 4th dive might be possible, but this is very unlikely. The wind tends to drop by about 17h00, and if it does, then there is the possibility of a night dive. But this can only be confirmed on the day, at about mid-afternoon.
Remember when diving anywhere off the coast of Mozambique you are thousands of kilometres from the nearest medical facility and recompression chamber with the result that all dive operators in Mozambique do not allow “pushing the limits” and prefer to err on the side of caution, so as to minimise the possibility of any dive accidents. There is no technical diving or deep de-co diving in Mozambique.
That’s the whale shark story.