Devil's Hole Pupfish
Channel: FWSPacificSouthWest
Date: 2011-09-21

Devils Hole pupfish (Cyprinodon diabolis) was listed as endangered in 1967. This iridescent blue inch-long fish's only natural habitat is in the 93 degree waters of Devils Hole.  Devils Hole located within the Ash Meadows National Wildlife Refuge, Nye County, Nevada, which is a detached unit of Death Valley National Park .  

The surface area of Devils Hole is approximately 10 X 50 feet the cavern is over 500 feet deep.  Pupfish live in the top 80 feet of the pool, are believed forage to spawn exclusively on a 7X13 foot shallow rock shelf just under the water's surface. 
The pupfish are believed to have been isolated in Devils Hole for 10,000 to 20,000 years.  Endemic species with limited distribution like the Devils Hole pupfish are at greatest risk of extinction since they do not have the flexibility to change locations to adapt to changing environments.  
Past research has demonstrated that Devils Hole pupfish population naturally cycle with the largest number of pupfish occurring in the fall and declining over the winter.  Although they spawn year round, adults that survive the winter produce most of the next generation of pupfish in the spring. 
Since population surveys began, Devils Hole pupfish numbers have not exceed 553 individuals. For reasons that are still unclear, the population of Devils Hole pupfish began to decline in the mid 1990's. By the fall of 2006, an estimated 38 fish remained in the wild and two refuge populations were lost.