Thousands of animals worldwide are killed through poaching every year for items like ivory, medicine, and sport. Poaching has drastically reduced populations of tigers from 100,000 in 1900 to only 4,000 in 1990 and cut Africa's elephant population in half by killing them for their tusks. Rhinoceros are also poached for their horns, which are sold for high prices in China due to traditional beliefs. Sharks have their fins sliced off and are thrown back in the ocean unable to swim so their fins can be used for cancer treatments. However, organizations are working to stop poaching and protect endangered species.