page_title: Devils Hole pupfish
section_title: Ex situ conservation
hierarchical_section_title: Devils Hole pupfish / Conservation and status / Recovery actions / Ex situ conservation
caption_attribution_description: (Unused) pupfish refugium at School Springs, Ash Meadows, southern Nevada
context_page_description: The Devils Hole pupfish is a critically endangered species of the family Cyprinodontidae found only in Devils Hole, a water-filled cavern in the US state of Nevada. It was first described as a species in 1930 and is most closely related to C. nevadensis and the Death Valley pupfish. The age of the species is unknown, with differing analyses offering ranges between one thousand and sixty thousand years. It is a small fish, with maximum lengths of up to 30 mm. Individuals vary in coloration based on age and sex: males are bright metallic blue while females and juveniles are more yellow. A defining trait of this species its lack of pelvic fins. The pupfish consume nearly every available food resource at Devils Hole, including beetles, snails, algae, and freshwater crustaceans, with diet varying throughout the year. It is preyed on by the predaceous diving beetle species Neoclypeodytes cinctellus, which was first observed in Devils Hole in 1999 or 2000. Reproduction occurs year-round, with spikes in the spring and fall. Females produce few eggs, though, and the survivorship from egg to adult is low. Individuals live 10–14 months.
context_section_description: Due to the fear of extinction in the 1960s and 1970s, several measures were taken to create multiple populations of the pupfish outside of Devils Hole to safeguard the species, which is known as ex situ conservation. Some of these measures, such as transplanting the fish into nearby natural springs, quickly failed. The fish disappeared, though one population at Purgatory Spring was destroyed by biologists, as the fish were misshapen and no longer looked like Devils Hole pupfish. Two attempts were made at this time to establish aquaria populations, one at Steinhardt Aquarium and the other at Fresno State College, though these also failed. A number of artificial "refugia" consisting of concrete tanks approximating conditions in Devils Hole were attempted to ensure the species' survival should the natural population at Devils Hole die out. The Hoover Dam Refugium for Endangered Desert Fish was established in August 1972, with the first twenty-seven pupfish translocated in October 1972. The Hoover Dam Refugium was successfully maintained for several years and reached a population of several hundred, though the sex ratio was highly skewed towards males with as many as three males per female. In 1985 or 1986, a component of the water supply system failed, however, killing many of the fish. Nearly all the remaining fish were killed by October 1986 when an additional failure caused the water temperature to drop drastically. The lone surviving fish was then removed. In 1973, a second refugium was established at Ash Meadows National Wildlife Refuge (AMNWR), the Amargosa Pupfish Station, also known as the School Springs refuge. From the founding population of twenty-five fish, it remained at several dozen individuals until a power failure in August 1984 disrupted the water flow, reducing the population to seven. The population increased to 121 by October 1987. In 1990, a third refugium was constructed, also at AMNWR, called Point of Rocks refuge.
  Maintaining the refugia populations has been largely ineffective, blamed on the small founder population size of each refugia as well as maintenance failures. The Point of Rocks refuge population unexpectedly had individuals appear with pelvic fins, which are not found in the species. Genetic evidence showed that around three individuals of the closely related C. nevadensis, which do have pelvic fins, invaded Point of Rocks between 1997 and 2005, hybridizing with the Devils Hole pupfish. The C. nevadensis genes quickly became highly prevalent in the gene pool, with researchers concluding, "...we  add  hybridization  to  the  long  list  of problems that have conspired against successful  propagation of C. diabolis in artificial settings outside of its native habitat". The School Springs population was extirpated in 2003, the Hoover Dam refugia population became extirpated once more in 2006, and the Point of Rocks refuge was extirpated in 2007.
  In May through August 2006, two pupfish from Devils Hole and five from the Hoover Dam Refuge were transferred to a Las Vegas Strip casino aquarium at Mandalay Bay with the hope of understanding how to breed the species in aquaria. Propagation efforts at Mandalay Bay failed, and by April 2007 all individuals had died or been transferred. Also in 2006, six younger pupfish were moved from Devils Hole to the Willow Beach National Fish Hatchery in Arizona. Additionally, the eighteen remaining individuals from the Hoover Dam refuge were moved to Willow Beach. While early breeding efforts appeared successful and four larvae survived to adulthood, all individuals had died by December 2006, possibly from a form of leukemia.
  In the early 2010s, a full-scale replica of the upper 6.7 m (22 ft) of Devils Hole was built at the new Ash Meadows Fish Conservation Facility (AMFCF), resulting in a 380,000 L (100,000 U.S. gal) tank. This refuge nearly mimics the natural Devils Hole, including water chemistry, spawning shelf, and natural sunlight. It intentionally differs, however, in temperature and dissolved oxygen content. The temperature is 2–3 °C (3.6–5.4 °F) cooler
caption: Pupfish refuge at School Springs, now defunct.
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