Great White Sharks
Let’s dive into Australian Marine Parks and learn more about the Great White Shark
In the crystal-clear marine park waters off the coast of Port Lincoln lies a once in a lifetime experience – swimming with the mighty great white shark!
Marine Parks provide the perfect location to dive down and see great white sharks, but fear not – it is all from the safety of a cage! Shark cage diving is described as one of the most magical and special ways to interact with these beautiful creatures as swimmers and divers get to experience them in their natural environment.
Great white sharks are found in most global coastal waters, and are also known as 'white sharks', 'white pointers', or the simple 'great white'.
These formidable creatures draw attention globally for their size and power. They can grow up to six metres long and have enough strength to launch their two-tonne bodies out of the water.
White sharks are able to live for longer than 30 or 40 years, with one study even suggesting that white sharks can reach 73 years old!
Importance of Marine Parks
Marine parks provide a safe place for marine species, including great white sharks. Not only are sharks protected from fishing pressure in marine parks, but they are also areas with more fish and prey for white sharks to hunt on.
The Neptune Islands, where shark cage diving occurs, is a protected area and forms part of the Neptune Islands Group (Ron and Valerie Taylor) Marine Park. The sharks are drawn to this area likely due to large numbers of long-nosed fur seals which reside and breed here and are also protected by the marine park.
Protecting prey items within marine parks help maintain the safety of magical creatures such as the elusive white shark.
Classification
White sharks are Chondrichthyes, a class that contains cartilaginous fishes - their skeletons are made of cartilage instead of bones. This class includes all sharks, rays, skates, and chimaeras.
White sharks are from the lamnidae (or mackerel) family, which also includes shortfin mako, salmon shark, and porbeagle sharks. White sharks are the only current species of the genus Carcharodon that are still alive on earth!
Kingdom – Animalia
Phylum – Chordata
Class – Chondrichthyes
Order – Lamniformes
Family – Lamnidae
Genus – Carcharodon
Species – C. carcharias
Did you know? White sharks are the only current extant (still alive on earth) species of the genus Carcharodon!
Distribution
Where can you find the white shark in Australia?
In Australia, white sharks can be found from northern Queensland, all the way along the southern coast to the north-western coast of Western Australia.
Australian white sharks are split into two genetically-different populations, the south-western population and the eastern population. 4 The south-western population, off the coast of Western Australia and South Australia, has an estimated population of 1,460 adult sharks, while the eastern Australian population has just 750 adults. 5 These populations cover the north-west, south-west, south-east and temperate east marine park networks.
Where can you find the white shark globally?
White sharks are found in most coastal waters globally. Usually, they are found in waters less than 100 metres deep – although there are records of white sharks swimming down to more than 1km below the surface. 2
White sharks are commonly spotted in South Africa, Guadalupe Island, California, and southern and eastern Australia.
Great white sharks prefer cool temperate to subtropical latitudes globally. Although their heat-exchanging circulatory systems mean that they can keep a body temperature up to 14 degrees above the sea water they swim in. 3
Satellite tagging has shown that great white sharks can also travel far distances across deep waters and spend extended periods offshore. The Australian white shark population tends to remain close to shore more than other populations, but they are still reported to travel to New Zealand across the Tasman Sea and one shark from South Africa came all the way to Western Australia.
Many of the waters where white sharks travel are unprotected from human pressures, so it is important, where possible, that marine parks are created to protect beautiful creatures like the white shark.
Habitat
White sharks are pelagic species, meaning they mostly swim in the middle of the water column. However, they are also often spotted on the water surface or on the ocean floor.
Marine parks provide important protection for the habitat of white sharks, keeping continental shelf breaks and seafloors safe from human pressures.
Sea Country
Great white sharks occur throughout First Nations’ Sea Country. Sea Country includes all oceans, beaches, land, and freshwater coastline. It covers all plants and animals, including the great white shark.
Sea Country encompasses the weather, sky, and People. It includes all living things, beliefs, values, spirits, and cultural obligations from coastal areas.
Great white sharks are mobile species, so can move throughout all areas of Sea Country. In Nauo Sea Country white sharks are often spotted.
Role in the ecosystem
What do white sharks eat?
White sharks aren’t fussy eaters – they happily eat a broad range of prey including large fishes, seals, sea lions, rays, whales, and other shark species.
Marine parks provide diversity hotspots and rich foraging grounds for white sharks to feed. Marine parks provide safe homes for Australian sea lions, seals, and pelagic fish, all of which are key food sources of the white shark.
Some studies have suggested that white sharks need to feed on about 30 kilograms of energy-rich prey every three weeks, which works out to be the equivalent of one seal pup every three days! 6
Hunting
White sharks are ambush predators, pouncing on their prey using a high burst of energy. White sharks swim slower than expected around seal colonies to increase the number of seals that they will come across (letting the seals come to them rather than searching for seals). Both of these strategies are used to save energy. 7
What eats white sharks?
The only oceanic animal which has been documented to prey on white sharks is the killer whale. Although juvenile white sharks could potentially be attacked by larger shark species.
Historically, humans may have hunted white sharks or caught them for trophies – although this is now banned in Australian waters.
Reproduction
Reproduction and mating of white sharks is a great unknown, with limited sightings of mating in the wild having occurred... We do know, however, that all shark species (including white sharks) have internal fertilisation, but where or how that occurs is still being discovered.
Despite this, scientists have some information on the reproductive strategy and cycle of white sharks. White sharks are aplacental viviparous, meaning that the baby sharks (pups) grow inside the uteri of their mother and are birthed live, but there are no placenta or umbilical cord. White shark pups are grown in their mothers for up to eleven months before they are born as fully independent, one-metre-long baby great white sharks!
White sharks can have between two and ten pups in each litter – although there has been one record of a female with 17 baby sharks!
Tourism
Worldwide, shark cage-diving is a popular tourist activity allowing divers and swimmers to witness white sharks in their natural environment, all in the safety of a cage.
Globally, the most popular places to dive with sharks are South Africa, California, Guadalupe Island, and, of course, South Australia!
Researchers and tourist operators are careful to ensure the cage-diving industry has minimal negative impacts on the white shark and ecosystem of the Neptune Islands. 8, 9, 10, 11, 12 While some changes to the residency of white sharks have previously occurred, the government, scientists, and the industry have worked together and developed new management regulations that have returned residency back to baseline levels.
In South Australia, the sharks aggregate at Neptune Islands Group (Ron and Valerie Taylor) Marine Park, off Port Lincoln, with a number of different companies taking day-trip or multi-day tours to the area. Sharks are attracted to the boat using a variety of methods, from bait to blasting loud music underwater!
Shark cage diving tourist operators in South Australia include Calypso Star Charters for day trips or Rodney Fox Shark Expeditions for longer adventures.
Environmental Threats
The white shark is classified as globally vulnerable on the IUCN red list, as they have the potential to become endangered unless the circumstances which are causing them to be under threat improve.
The white shark's low reproductive rate, along with their late sexual maturity and long gestation period make white sharks particularly susceptible to pressures such as overfishing and environmental change.
In the case of white sharks, they are not often commercially targeted for fishing, but recreational fishing for trophy jaws, catches in shark control programs, and bycatch led to concern about the conservation status of the species. While white sharks are illegal to catch in Australia presently, white sharks can still be caught in shark control programs, which might slow down the recovery of the species.
This factsheet is part of the University of Adelaide's Fab Five project, focused on raising awareness of five fabulous species and the marine parks that help protect them. This 'Our Marine Parks Grants' project received grant funding from the Australian Government.
References
1. Hamady, L.L., et al., Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks. PLOS ONE, 2014. 9(1): p. e84006.
2. Bradford, R., et al., Evidence of diverse movement strategies and habitat use by white sharks, Carcharodon carcharias, off southern Australia. Marine Biology, 2020. 167(7): p. 96.
3. Harding, L., et al., Endothermy makes fishes faster but does not expand their thermal niche. Functional Ecology. n/a(n/a).
4. Blower, D.C., et al., Population genetics of Australian white sharks reveals fine-scale spatial structure, transoceanic dispersal events and low effective population sizes. Marine Ecology Progress Series, 2012. 455: p. 229-244.
5. Bruce, B.D., et al., A national assessment of the status of White Sharks, in National Environmental Science Programme, CSIRO, Editor. 2018, Marine Biodiversity Hub: CSIRO.
6. Semmens, J.M., et al., Feeding requirements of white sharks may be higher than originally thought. Scientific Reports, 2013. 3(1): p. 1471.
7. Watanabe, Y.Y., et al., Swimming strategies and energetics of endothermic white sharks during foraging. Journal of Experimental Biology, 2019. 222(4).
8. Meyer, L., et al., The impact of wildlife tourism on the foraging ecology and nutritional condition of an apex predator. Tourism Management, 2019. 75: p. 206-215.
9. Meyer, L., et al., The effects of wildlife tourism provisioning on non-target species. Biological Conservation, 2020. 241: p. 108317.
10. Huveneers, C., et al., Interacting with wildlife tourism increases activity of white sharks. Conservation Physiology, 2018. 6(1).