JOIN USThe great white shark, the one that most frequently comes to mind, is a protected species -- though that hasn't prevented its stocks from declining -- but tens of millions of other sharks are caught each year by fishermen.
Why are they in such demand? Their fins are the main ingredient in shark fin soup, a prestigious dish in traditional Chinese cuisine, and even in Europe shark meat is often served to consumers, usually without their knowledge.
"People don't realise they're eating shark because it's not called shark, but they are," Sonja Fjordham, the head of Shark Advocates International, told AFP on the sidelines of an international conference this week on migratory species in Bergen, Norway.
The name can be misleading: "rock salmon" often sold in fish and chips shops in Britain, Australia and elsewhere is actually a small type of shark called spiny dogfish.
Ecologists' main concern is the practice known as "finning", when fishermen cut the fins off of sharks and then throw the fish back in the water, usually still alive and leaving them to a certain death by drowning, suffocation, blood loss or to be devoured by other fish.
In Asia, where shark fin soup is a sign of status and social standing, a fin can cost several hundred dollars (euros).
"It's as if you cut the arms and the legs off of a person. It's just a torso. Without fins, they can't swim, they can't breathe, they can't eat, they just sink to the bottom," explains Rebecca Regnery, the deputy director of the Humane Society International.
Finning, which is often carried out on by-catches but also targetted ones, weighs heavily on species that have slow reproduction patterns.
Bans on the practice exist in many countries but are often ignored.