Sharks are under serious threat around the globe. It is estimated that up to 70 million sharks are killed by people every year, due to both commercial and recreational fishing. The International Union for Conservation of Nature (IUCN) has classified 17 percent of more than the 1,000 species assessed as threatened, according to its 'Red List' criteria. Sharks are caught intentionally or as accidental "by-catch" in virtually all types of fisheries worldwide.
By-catch in general is a serious threat for biodiversity worldwide, and sharks seem to be particularly vulnerable. About 6.8 million tons of accidentally caught fish and mammals and hundreds of thousands sea birds are discarded every year. Being the most frequent threat for sharks, by-catch accounts for 66.9 % of shark species that have an unfavorable conservation status as reported by the IUCN.
Finning is another major threat facing so many of the imperiled shark species. It involves the removal of shark fins while the rest of the body is discarded into the ocean. It is estimated that the number of sharks killed each year ranges from 26 million to 73 million to support the global shark fin market. Shark fins, used in the traditional Asian dish shark fin soup, are among the world's most valuable fishery products. The price of shark fins reached more than US$ 700 per kilo in 2011, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). It has become increasingly clear that the international demand for shark fins is the driving force behind most shark fisheries today.
Sharks are also sought after for their meat and liver oil and, increasingly, their cartilage skeletons are also marketed. Meat and fins are used for consumption, skins for leather, liver oil for lubricants, cosmetics and as a source of vitamin A, cartilage as a medical supplement and jaws and teeth for curios. Although it might appear that the use of the entire shark is a positive reduction in waste compared to finning, most of these fisheries are currently conducted at levels that are unsustainable. Indeed, illegal, unreported and unregulated (IUU) fishing of these inherently vulnerable species is the main reason for their placement in Threatened categories of the Red List.
Not only direct threats such as fishing account for the depletion of shark species but also indirect influences such as pollution, habitat alteration, damage and loss due to coastal development.
Most sharks are long-living species that grow slowly, mature late, and have low reproduction rates. These biological factors make sharks particularly vulnerable to overfishing and mean that populations can be slow to recover once depleted. The continuous depletion and even eradication of these top predators in the structure of many marine habitats will have catastrophic consequences for ecosystems such as coral reefs and may cause the extinction of many other interdependent species.