Fur traders once hunted sea otters to near extinction, their numbers dwindling to less than 2,000 during the early 20th century. The species now exists in about two-thirds of its former range at varying levels of recovery. Although the hunting of otters is no longer permitted except for limited harvests by indigenous peoples, the species is threatened by predation, poaching and entanglement in fishing nets. However, oil spills are the animal’s greatest threat. Otters are particularly vulnerable to oil spills because they rely on their fur to keep them warm, but when their fur is soaked with oil it can no longer retain air and the otters die quickly from hypothermia. The 1989 Exxon Valdez oil spill killed an estimated 2,800 otters, and the lingering oil in the area continues to affect the population.