Why is the white shark's future endangered?

Résumé du document

Sharks are marine predators, well known as bloodthirsty killers by humans owing to the incidence of shark attacks and subsequent human casualties. But for these 4 or 5 people killed in a year, almost 100 millions of sharks are killed each year. According to the association "Shark savers", 97 to 99% of regional populations of shark species are gone already, and within 5 to 10 years, there will be no more sharks in the water. The great white shark is now listed as "vulnerable" in the International Union for the Conservation of Nature (IUCN) Red list, because it is currently in a high risk of extinction. It is now more urgent to protect them because they have a very important role to play in the functioning of an ecosystem in the oceans, as keystone species. This aspect will be developed later in this report.

Indeed, multiple causes are involved and humans are, of course, responsible for this massacre. Many governments are now aware of the magnitude of this phenomenon, and steps have been taken, but the killing persists, and the white shark in all likelihood will become extinct. The great white shark is one of the most dangerous sharks in the world. Its name was given because of the white color on its abdominal area, despite the fact that its back is grey. Its Latin name 'Carcharodon caracias' means "shark with sharp teeth" in Greek. It deserves its name because its teeth cut like a razor blade, it allow the white shark to kill any prey. the teeth can renew itself in their entirety in just 8 days. The white shark can be found near the shore in cold water as in warm water.

Extraits

[...] The white shark is located near the shore in cold water as in warm water. Fig.1: Map showing the geographical distribution and abundance of the focal points of the white shark in the world Life expectancy is estimated at between 25 to 30 years, it has a maximum size in excess of 6 meters and its weight is almost 3 tons. White sharks have a very low reproductive rate, in fact, they have a late sexual maturity (about 10 years for males), females are ovoviviparous and the gestation period is about one year. [...]

[...] The great difficulty for the protection of this species is that it is migratory and therefore they go through national waters and international waters while inducing the problem of different authorities and their power. Conclusion Despite of its status of “high level predator”, the Great White Shark is extremely fragile. Due to its low reproductive rate and its several threats it is facing, it is now listed as “vulnerable” in the IUCN red list. The consequences of its extinction are not yet well understood by the scientists, but it seems that this will entail an overall upheaval of the marine ecosystems. [...]

[...] The measures taken by the authorities to forbidden its fishing are no longer sufficient. References: - Great white shark population lower than previously believed http://www.csmonitor.com/Environment/Wildlife/2011/0311/Great-white- shark-population-lower-than-previously-believed - Population Growth Rates of Reef Sharks with and without fishing on the Great Barrier Reef : Robust estimation with Multiple Models - Sharks in danger of extinction http://sharksavers.org/education/sharks-are-in-trouble/70-sharks-in-danger- of-extinction.html - Collapse and Conservation of Shark Populations in the Northwest Atlantic http://www.cfr.washington.edu/classes.esrm.450/Baum2003.pdf - The Role of Sharks in the Ecosystem http://www.mesa.edu.au/seaweek2005/pdf/infosheet04.pdf - White shark ecology and conservation http://www.elasmo-research.org/education/white_shark/conservation.htm - The Role of Sharks and Longline fisheries in a Pelagic Ecosystem of the Central Pacific http://www.stanford.edu/group/Palumbi/manuscripts/Kitchelletal2002.pdf - White Shark Carcharodon carcharias: status and management challenges http://www.cites.org/common/com/ac/20/E20-inf-01.pdf Why the white shark's future is endangered? [...]

[...] Indeed, because of his size, it can't escape of being captured by fishing nets. We must also understand that man acts as a competitor because of overfishing greatly reduces the amount of prey available, and this is one of the causes of its progress towards the coast where it is strongly threatened. Besides, sharks can represent an important economic source in alimentary sector or in leisure activities (represented by trophies). Indeed, its flesh can be used for making Asiatic soups or others traditional meals. [...]

[...] In fact, when a predator's population is reduced, the population of the main prey begins to explode. They are so many that they eat themselves, from lack of food. This will change the entire ecology of a marine ecosystem, and it could be a worldwide effect. Fig.2: simplified diagram of a marine food web In the Caribbean, scientists have found that the corals were dying because of the overgrowth of algae. Indeed, local people took away the sharks from the coral reefs, which resulted in an increase in intermediate carnivores, and thus ate more fish herbivores. [...]