Whale sharks

The Ningaloo Coast is famous for the whale sharks that aggregate on Ningaloo Reef between April to August each year, which lends itself to one of the most exciting and rewarding experiences of many people's trip to the region - swimming with whale sharks.

Biology

The whale shark (Rhincodon typus) is the world's largest living fish - reaching a maximum size or around 20 m in length.  The whale shark has a mouth which can be up to 1.5 metres wide, a broad flat head and two small eyes located towards the front of the head.  Three ridges run along the side of each animal and there are five large pairs of gills which they use for filter feeding. The body is greyish, bluish or brownish above, with an upper surface pattern of creamy white spots between pale, vertical and horizontal stripes, and a white belly.  These spots are unique to each whale shark and because of this they can be used to identify each individual animal.

Despite their large size, whale sharks are one of only three filter-feeding sharks (the other two are the basking and megamouth sharks) that feeds on very small plankton including small crustaceans like krill, copepods and crab larvae as well other tiny invertebrates such as squid, small fish and jellyfish.  Whale sharks have thousands of tiny teeth arranged in more than 300 rows but they neither bite nor chew their food.  Instead, the shark sucks in a mouthful of water, closes its mouth and sieves prey as small as a millimetre through the fine mesh of the gill rakers.  They are able to open their mouth wider than a metre, which optimises feeding. Unlike the megamouth and basking sharks, the whale shark does not rely on forward motion but can hang vertically in the water and ‘suck' in food.

The whale shark is largely solitary and is rarely seen in groups unless feeding at locations with abundant food.  Males range over longer distances than females and they can dive to great depths of 1500 m.  Whale shark eggs hatch inside the mother's body and the females give birth to live young between 40 to 60 cm long.  It is believed that they reach sexual maturity at around 30 years and their life span has been estimated to be between 70 and 180 years.

Distribution

The whale shark occurs in all of the world's tropical and warm-temperate oceans, usually between latitudes 30°N and 35°S, and is thought to prefer surface sea-water temperatures between 21 to 25°C.  Whale sharks are known to inhabit both deep and shallow coastal waters and the lagoons of coral atolls and reefs.  Western Australia is one of the most reliable locations to find whale sharks in the world.  From around mid-March to mid-May each year they are common in Ningaloo Marine Park.  At times, in December and January, they have also been seen as far south as Shark Bay and even Kalbarri.  The sharks regularly appear at locations where seasonal food 'pulses' are known to occur, for instance, the mass spawning of coral triggers the arrival of whale sharks at Ningaloo Marine Park.

Threats

While little is known about the natural threats to whale sharks, humans are the biggest threat to whale shark populations.  Hunting is banned in most countries but illegal fishing still exists.  In Taiwan, whale sharks are known as ‘Tofu fish' because of the taste and texture of their flesh, and their fins can fetch up to US$15,000 on the black market for use in shark fin soup.  Whale sharks are also vulnerable to boat strikes as they often swim at the surface.

Conservation

The whale shark is protected in Australian waters under State, Commonwealth and international legislation and it is illegal to disturb, harm or fish for whale sharks. The population of whale sharks is unknown and the species is listed as vulnerable to extinction in the IUCN Red List of Threatened Species.

Swimming with whale sharks at Ningaloo

The Western Australia Department of Environment and Conservation (DEC) is responsible for the conservation and management of Western Australia’s wildlife, lands, waters and resources for the benefit of present and future generations.  As such, DEC are responsible for the protection and management of whale sharks within Western Australian waters.  That said, Ningaloo Marine Park is a multiple-use Marine Park and access is permitted to users to interact with whale sharks within the Marine Park waters.

To assist in the management of the recreational use of whale shark interactions, DEC has introduced a licensing system for all persons who wish to run whale shark interaction tours.  Only persons who are licensed by DEC are permitted to conduct commercial tours with whale sharks.  Two codes of conduct have been developed in conjunction with tour operators - applying to people swimming with whale sharks, and for vessels (both private and commercial) operating in the vicinity of a whale shark.

To ensure that interacting with whale sharks is a safe and enjoyable experience and to prevent the animals themselves from being harmed or disturbed, the following Code of Conduct applies when interacting with whale sharks.

click image for larger image view

Exclusive contact zone:

• An exclusive contact zone of a 250 m radius applies around any whale shark.
• Only one vessel at a time may operate within the zone for a maximum time of 90 mins and at a speed of 8 knots or less.
• The first vessel within that zone is deemed to be ‘in contact’.  The second vessel to arrive must keep a distance of 250 m from the shark, and any other vessels must be 400 m from the shark.

Vessel operators in the contact zone:

• Must not approach closer than 30 m to a shark.
• Should approach from ahead of the shark’s direction of travel when dropping swimmers into the water.
• Must display both whale shark (commercial vessels only) and dive flags when swimmers are in the water.
• Commercial tour operators operate under similar requirements to other vessels but have specific licence conditions that apply to their operation.

Swimmers in the contact zone must not:

• Attempt to touch or ride on a whale shark.
• Restrict the normal movement or behaviour of the shark.
• Approach closer than 3 m from the head or body and 4 m from the tail.
• Undertake flash photography.
• Use motorised propulsion aids.
• Exceed more than 10 people in the water at any one time.

For more information, contact the DEC Exmouth District office.