Many animal welfare groups such as the World Animal Protection consider keeping dolphins in captivity to be a form of animal abuse. The main arguments are that dolphins do not have enough freedom of movement in pools, regardless of pool size, (in the wild, dolphins swim hundreds of miles every day) and do not get enough stimulation. Dolphins often show repetitive behavior in captivity and sometimes become aggressive towards other animals or people. In some cases, the behavior of dolphins in captivity also results in their own death.