The Great White Shark, (Carcharodon carcharias) is also known as the White Shark or White Pointer, is widely distributed, and located throughout temperate and sub-tropical regions in the northern and southern hemisphere. In Australia, its range extends primarily from Moreton Bay in southern Queensland around the southern coastline and to North West Cape in Western Australia.
Due to their rarity and size, it is relatively difficult to obtain information on the biology of Great White Sharks. It is known that the females mature at between 4.5-5.0 metres and attain a greater length and weight than males. Males mature at about 3.6-3.8 metres.
The gestation period is unknown, but is thought to be approximately 18months, with females breeding only every 2-3 years. Female Great White Sharks produce up to 10 pups per litter.
Great White Shark pups are fully developed and independent at birth. They are 1.2-1.5 metres in length and may weigh up to 32kg. Longevity in these sharks is unknown but is considered to be in excess of 30 years.
Although it is difficult to assess the population size of Great White Sharks, available data indicates a decline in abundance and size of the species in some areas of Australian waters.
The Great White Shark is fully protected in Commonwealth waters under the Environment Protection and Biodiversity Conservation Act 1999, which lists it as a vulnerable species. The listing was the result of a nomination from HSI and was based on a number of factors, including evidence of a declining population, its life history characteristics (long lived and low levels of reproduction), limited local, distribution and abundance and bycatch in commercial fisheries.
The Great White Shark is also fully protected in the coastal waters of Tasmania, South Australia, Victoria, New South Wales and Queensland.
Commercial fishers threaten Great White Sharks. Although not specifically targeted, they are caught as bycatch on long liners and in the nets of professional fishers and in fin fish farm cages such as tuna farms. This is currently thought to be the largest cause of mortality for Great White Sharks.
The estimate of Great White Sharks caught by commercial and recreational fisheries is between 100-440 each year throughout Australian waters.
Great White Sharks are also caught by shark control activities including beach meshing and drumlines, which most often kill the captured shark. Some non-lethal methods are being trialed include using electrical fields to repel sharks, but these practical trials have encountered many logistical problems. Great White Sharks are a target species in control activities but other non-target species are impacted by shark meshing such as turtles, dugongs and dolphins.
Queensland and NSW are the only two states to employ beach meshing. In Queensland a mixture of baited drumlines and nets are used. Drumlines consist of a marker buoy and float supporting a trace and baited hooks anchored to the bottom.
There is also an illegal trade in Great White Sharks for trade in trophy products (such as jaws and teeth) and fins for food items such as “shark fin soup”. There are several Australian fisheries that take shark fins as a by-product. Dried shark fins can attract a high price on Asian markets. There is growing concern that shark finning is both wasteful, when the fins are removed and the carcass discarded. This method is also a possible inducement to fishers to actively target sharks.
It has been argued that tourism has a negative indirect impact on Great White Sharks, whereby it can limit the recovery of the population by altering the behaviour of the animal. Both shark cage diving and shark boat tours depend on attracting the sharks to the boat through a process called “chumming”. This involves releasing a mixture of fish oil and/or animal products into the water at regular time intervals to develop a slick to attract sharks into the vicinity.
Some conservationists have come to the conclusion that “chumming” affects Great White Sharks negatively by making them habituate areas they would not normally visit, and learn to associate boats with food. Chumming adjacent to sea lion and seal colonies can have a detrimental effect on these animals as Great White Sharks deplete the population. Tourism also raises the question of whether Great Whites are disturbed whilst catching their natural prey.
Tag and release schemes have been blamed for the death of some Great White Sharks. If they are not carried out with due care or prior knowledge, the sharks have been known to die through the stress of capture.
HSI proposes that tag and release programs of Great White Sharks must be assessed against the risk to individual sharks and the benefit of the knowledge that is proposed to be gained. We do not support tagging programs where it is simply an excuse recreational fishers use to justify targeting the animals for fun.
Out of concern for the international trade in shark jaws and teeth for trophies, HSI lobbied the Australian Government to nominate the species for CITES protection. They agreed but unfortunately, the nomination was not successful at the CITES meeting in 2000. It fell short of the 2/3 majority of country votes needed to secure a listing. However HSI will urge the Australian Government to try again at the next CITES meeting.
HSI has also nominated the 'nets and drumlines used on ocean beaches in shark control programs' as a Key Threatening Process under the Environment Protection and Biodiversity Conservation Act. We are urging New South Wales and Queensland Government to use non-lethal methods of bather protection.
Picture courtesy of Rachel Robbins