The Devils Hole Pupfish's only natural habitat is in the 93 degree waters of Devils Hole, located within the Ash Meadows National Wildlife Refuge, Nye County, Nevada, a detached unit of Death Valley National Park. Although the cavern is over 400 feet deep, the pupfish, a 22-thousand-year-old species, is believed to spawn exclusively on a shallow rock shelf just under the waters surface. By the fall of 2006, an estimated 38 fish remained in the wild. Since 2007, the population estimates have started to swing upward. The fall 2008 count was estimated at 127 fish; the first time triple digits have been estimated since 2004, and the first three year upward trend since 1996.Watch: PBS' Life In Death Valley