By Paul Barrett, Nevada Fish and Wildlife Office
Increasing the population size of devils hole pupfish (Cyprinodon diabolis) and establishing a population outside of Devils Hole is complicated and the situation is compounded by the small founder population, short lifespan, limited genetic diversity, and the difficulty of rearing them in captivity. A dive survey into Devils Hole in September 2007, resulted in 92 adult pupfish, a 7% increase over the September 2006 survey of 85 fish. This short-lived species (approximately one year) has a natural high and low cycle, with the population in the fall being larger than that in the spring due to natural die-off during the winter months

Managers and scientists are working collaboratively to identify the factors that contribute to successful propagation of pure Devils Hole pupfish and to understand how these factors interrelate.

Decisions have been carefully and deliberately made to try and increase the size of the single wild Devils Hole pupfish population and establish a viable population outside of Devils Hole. Directors and Managers from the U.S. Fish and Wildlife Service, the National Park Service, and the Nevada Department of Wildlife participated in a formal decision making process (known as structured decision making) on August 2006, to make difficult decisions on future actions to reverse the decline of the Devils Hole pupfish.

To facilitate timely and transparent decisions the three agencies formed a joint Incident Command Team consisting of a biologist from each agency.  This group coordinates recovery efforts and assists in their implementation and has developed an interactive population model that identified data needs.

Many basic life history parameters associated with the species are unknown.  Because the low numbers of pure Devils Hole pupfish in the wild and the difficulty in successfully propagating them in captivity, much research is needed to identify the best propagation methods are being done on a captive population of hybrid pupfish.  These hybrids are a cross of Devils Hole and Ash Meadows Amargosa pupfish.  In a cooperative effort between Fish and Wildlife Service Regions eight (Nevada) and two (Arizona), as well as private partners, these experiments occur at Willow Beach National Fish hatchery and Shark Reef at Mandalay Bay.

Supplemental feeding was initiated in January 2006, and appears to have increased the strength and vigor of adult pupfish in Devils Hole.  One of our next steps will be to develop methods that assist in the development of larval pupfish as they grow to adults.  This may include isolation within Devils Hole to protect them from predators or a larvae-specific food.

Other ongoing actions initiated by the Fish and Wildlife Service, National Park Service and Nevada Department of Wildlife include:

• larval pupfish surveys of Devils Hole;

• conducting research on disease issues;

• continuous outreach to both professional and lay audiences;

• implementing a variety of research activities to better understand the ecology of Devils Hole; and

• further refinement of our understanding of the genetics of Devils Hole pupfish in conjunction with academics and Dexter National Fish Hatchery.

Future actions being considered include, but are not limited to

• Movement of pure Devils Hole pupfish eggs into captivity; and

• Developing a monitoring program based on a workshop involving outside experts held in the Spring of 2007.

Recovery of the Devils Hole pupfish will be a long process requiring vigilance.  Temporary setbacks are inevitable and because the population is so low a single catastrophic event could irreparably harm the species.  Nevertheless, the three action agencies are committed to working together and recent events and progress suggest the efforts are showing success. 

Recent Devils Hole Pupfish Survey Results
November 2005	84
April 2006	38
September 2006	85
April 2007	38
September 2006	92

For additional information on the Devils Hole pupfish, please review the Journal Article: (Jul 2007)   NEVADA: Species Update: The Devils Hole Pupfish, or visit the Nevada Fish and Wildlife Office web site at www.fws.gov/nevada.