A major problem with assessing the status of the world's shark populations is finding them. Many sharks species are rarely seen. The IUCN Red List lists numerous sharks that can't yet be categorised because we simply don't know enough about them.

• The Ganges shark (glyphis gangeticus) is found in the Ganges river area in estuarine and inshore waters. Our sum knowledge of them has been derived from three ancient museum specimens. This species is critically endangered. It should not be confused with the bull shark (Carcharhinus leucas) which is also sometimes called the Ganges shark.



• The Borneo shark is classified as endangered. Once again, it is found inshore and in coastal areas and has not been widely studied. It is threatened by a rise in shark fisheries in the region.
• Other shark species listed as endangered include the rare speartooth shark that is at risk from increased coastal development in the Indo-Pacific region which is rapidly destroying its coastal and river habitat. The whitefin tope shark is also struggling for survival in the overfished waters around the Philippines. Its range is extremely restricted and there is no recent information.



• You might think that a good strategy for sharks would be to head for the depths, but you'd be wrong. The smoothback angel shark is a bottom-dwelling species found off Brazil in the waters of the western South Atlantic shelf. Here the species is being depleted by bottom-trawl fisheries. The problem is made worse by the fact that the smoothback angel shark is particularly slow to mature - young sharks are caught before they have a chance to breed.



• Many more sharks' species that are not yet endangered could be soon if current trends continue. A number of 'lower risk' classifications are considered to be 'near threatened' or 'conservation dependent'. Similarly, many species classified as 'vulnerable' are more at risk in some areas than the category would imply. Here are just a few of them.



• The great white Shark
  The film Jaws brought the great white star status but also fuelled demand for great white shark products, strange though it may seem to use an animal's dental work as an ornament. Peter Benchley, the author of the book, has been prominent in the campaign to stop the practice of shark finning but conservationists are still concerned that the film perpetuates the idea that the only good shark is a dead one.



• Great whites mature late and have few young and they are caught as bycatch as well as being deliberately targeted.



• Studies have shown that great whites are declining, both in number and size. They are protected in some areas, but even if they are, the conservation measures are not always enforced with much vigor.



• Basking Shark
  The basking shark is the second largest fish in the world. It is often seen in British coastal waters. Certain sub-populations, especially those in the North Pacific and Northeast Atlantic, have been seriously overfished in recent years. The basking shark has a particularly large dorsal fin, which may be its downfall at a time when the demand for shark fin soup is increasing.



• Basking shark numbers have been falling rapidly because of over-exploitation in some areas. There are real concerns that populations will never recover because the fish mature so slowly and have such a low reproductive rate.



• In November 2002, basking sharks were added to Appendix II of the Convention on International Trade in Endangered Species (CITES). This means that basking shark products can only be sold with special permits. They've been protected in waters within 20 km of the British coast for some time.



• Whale Sharks
  Whale sharks are gentle giants and are particularly vulnerable because they move slowly and close to the surface. Like their name-sakes, they are targeted by harpoon fisheries because their meat and fins fetch a high price on the international market. Even back in 1999, a single whale shark fin was on sale in Beijing for £11,000.



• Paradoxically, whale sharks could play an important role in eco-tourism because they are no threat to humans and are safe to swim with. There is a growing interest in them among the dive community. In November 2002, whale sharks were added to Appendix II of the Convention on International Trade in Endangered Species (CITES). This means that whale shark products can only be sold with special permits.



• The Sand Tiger Shark
  The sand tiger inhabits coastal waters and lives in isolated populations that don't mix. They are now threatened by fishing activity, including spear fishing and beach meshing.



• Populations in Australia and South Africa have been studied and are showing a marked decline. Sand tigers are protected in Australia but even there, there is little sign of recovery.