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The Fish ...Population ...Community ...Habitat ...Management ...Law

• Kingdom: Animalia Linnaeus, 1758 - animals
  • Subkingdom: Bilateria (Hatschek, 1888) Cavalier-Smith, 1983 - bilaterians, triploblastic animals
    • Branch: Deuterostomia Grobben, 1908 - deuterostomes
      • Infrakingdom: Chordonia (Haeckel, 1874) Cavalier-Smith, 1998
        • Phylum: Chordata Bateson, 1885 - chordates
          • Subphylum: Vertebrata Cuvier, 1812 - vertebrates
            • Infraphylum: Gnathostomata auct. - jawed vertebrates

              Class: Osteichthyes Huxley, 1880 - bony fishes
              Order: Cyprinodontiformes Berg, 1940 - cyprinodontiforms, cyprinodonts
              Family: Cyprinodontidae (Greek for "Family of Toothed Goldfish")
              Genus: Cyprinodon
              Species: diabolis
              Scientific Name: Cyprinodon diabolis Wales, 1930
              Author: Wales, 1930
              

• In this clip created by the PBS serial, Nature, you can "Meet" the infamous Devils Hole Pupfish.
• Most of the 13 species of Cyprinodon (Pupfish) in the United States are restricted to springs or streams in the deserts of Texas, New Mexico, Arizona, Nevada, and California.
• Of all known endangered
• “If evolution were the X-games, the tiny, tough pupfish would take the gold in the Animal Kingdom competition. Living in shallow desert pools and streams in California, Arizona, and Mexico, these colorful, stubby fish tolerate extreme fluctuations in temperature, salinity, and dissolved oxygen. They live fast, maturing within 2 to 3 months from birth, and die young, at the average ripe age of 6 to 9 months. Subsisting mainly on algae, they may spend their entire lives in stagnant, salty ponds as little as an inch deep.” fish species, the Devils Hole Pupfish is the number one, most endangered fish. (An article from the early1980's)
• Only 2 North American members of the pupfish genus Cyprinodon are currently not in jeopardy.
• The Devils Hole pupfish is the smallest of the desert cyprinodon fishes rarely reaching 25 mm total length with a majority of individuals much smaller.
• This type of pupfish rarely exceeds 0.98 inches (25 mm) in length, and has a life span of about 1 year.
• The Devil's Hole Pupfish, a species that may be as much as 10,000 years old, were declared an endangered species in 1967, one of the very first to receive that designation.
• “The Devil's Hole pupfish first came to the attention of science in the 1890's when it was classified as Cyprinodon nevadensis, the Nevada pupfish, and slightly later as Cyprinodon macularius, the present name of the desert pupfish. It wasn't until 1930, when Joseph Wales published his biometrical studies of the pupfish of the Death Valley region, that the unique nature of this fish was recognized and it was assigned its present designation as Cyprinodon diabolis.”
• The Devils Hole Pupfish is a short-lived species (approximately 1 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.
• The peak spawning period for Devils Hole pupfish is between February and May. One theory is that this is possibly due to the fact that the physical environment is more stable with water temperature varying by only a few degrees, higher dissolved oxygen (DO) concentrations during late winter to early spring months and with benthic biomass (= potential food) increasing through the summer.
• In Devils Hole, spawning occurs mainly on the shallow shelf. Peak spawning appears to coincide and precede the peak algal growth in Devils Hole: between April and mid-June. Females lay small numbers of eggs, 4 to 5, on substrate, which are fertilized by the male.
• Normally it takes only 2- 4 months for Pupfish to reach maturity after hatching.
• Once a pupfish reaches a strong swimming stage it may live for 6- 9 months.
• Larval pupfish have been observed to be more inactive during the day, and ncrease activity after dusk and remain active throughout the night. Abundances peaks in March and April. Large juvenile and adult fish follow the opposite pattern.
• Studies on the reproductive ecology of other pupfish taxa suggest water temperatures in Devils Hole are likely to be near the upper maximum threshold for successful egg production and increases in young fish populations (i.e. fry recruitment). These studies also suggest small increases in water temperature on the order of a few degrees may be sufficient to decrease or eliminate successful recruitment of Devils Hole pupfish.

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• Devils Hole pupfish population resides in southern Nevada in a single small pool at the bottom of a limestone cave, where it has evolved in isolation for more than 10,000 years.
• Devils Hole pupfish occupy the upper 80 feet of the portion of the cavern system open to daylight. About 50% of the population occurs over the small, shallow rock shelf.
• Population size of Devils Hole pupfish fluctuates annually from a low in March and April to a high in August and September.
• The census counts of pupfish recorded during semi-annual dives into Devils Hole between 1997 to 2006 has declined from 275 individuals to 85 fish.
• An extreme demand on the aquifer system that feeds Devils Hole in the late 1960s and early 1970s led to a decline in the water level and was the causal factor that resulted in a population decline to a low of 124 individuals for that period.
• The population of Devils Hole pupfish has not exceeded 553 individuals since surveys began in 1972.
• From the late 1970’s through 1996, the population appeared to be relatively stable with an average population size of 324 individuals.
• Since the late 1990's, federal biologists have been tracking falling numbers.
• Evidence suggests that as water levels in Devils Hole increased in the years immediately following the landmark court decisions of 1976 and 1984, fish numbers also exhibited a positive response. More recent data suggest that Devils Hole remains at risk: water levels have been gradually but consistently declining since 1988. Pupfish numbers, as represented by standardized counts, appear to have been declining since 1995.
• In 1997, the fall population surveys started to indicate a downward trend for unknown reasons.
• In August and September 2004, 2 separate rainfall events deposited 1.66 cubic meters of sediment on the main spawning shelf, for a loss of approximately 54 percent of pupfish spawning habitat.
• During the September 2004 flash flood, fish traps being used in a larval pupfish population study that were stored in a container near the Hole were washed into the water. One third of the Devils Hole pupfish population in September 2004 died due to this unfortunate incident.
• The adult population survey conducted in November 2005 indicated a population of 84 individuals.
• The spring survey in April 2006 indicated 11 larvae and 38 adult pupfish in their natural environment; the lowest count on record.
• During April 2006 the population at the Hoover Dam Refuge was also surveyed and yielded a total number of 29 individuals. Approximately half of those fish were estimated to be young fish, also indicating that successful spawning is occurring.
• On May 19, 2006, a total of 9 pupfish were moved to the Shark Reef aquarium and exhibit at the Mandalay Bay hotel-casino in Las Vegas Strip.
  • 2 of the 9 were female adults brought to the Shark Reef exhibit from a refugia at Willow Beach National Fish Hatchery in Arizona, a federal fish hatchery on the Colorado River below Hoover Dam, where biologists have been trying to raise a backup population of the fish.
  • 2 of the 9 were male adults, from the Devils Hole population, part of Death Valley National Park along the Nevada-California border.
  • 5 fingerling pupfish were moved from Devils Hole to the Willow Beach refugia as part of a plan to establish Devils Hole pupfish in the Mandalay Bay hotel Shark Reef aquaria exhibit.
• After the moves on May 19, 2006, an estimated 36 adult pupfish remain in Devils Hole, the species' only known natural home, a water-filled subterranean cavern about 100 miles west of Las Vegas.
• 85 adult pupfish were counted during the September 2006 population census.

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• The 1967 to present studies have identified the following species living in and around the waters of Devils Hole:

  Consumers

  • amphipods (Hyalella sp)
  • ostracods
  • flatworms (Dugesia dorotocephala),
  • beetles
    • Devils Hole warm springs riffle beetle (Stenelmis calida calida),
  • Spring snail (Tryonia variagata)
  • various protozoa

  Producers

  • green alga (Spirogyra sp., Oscillatoria sp.)
  • cyanobacteria (Plectonema wollei and Chroococcus)
  • diatoms (Denticula sp. and others)

  It should be noted that the presence or populations of these organisms are in constant flux and some times may appear absent altogether.

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“It is an ecological truism that organisms do not exist in isolation, but are relevant only as components of, and in reference to, their environments. It follows, then, that to understand the Devils Hole pupfish we also have to understand the Devils Hole environment.” (2003 Desert Fish Council Meetings Abstract )

• Most of the 13 species of Cyprinodon (Pupfish) in the United States are restricted to springs or streams in the deserts of Texas, New Mexico, Arizona, Nevada, and California.
• Devils Hole, the Devils Hole Pupfish species' only known natural home, is a water-filled subterranean cavern about 100 miles west of Las Vegas.
• Devil's Hole is located in a range of low desert hills at an elevation of 732 meters (2400 feet) above sea level on the fringe of Ash Meadows, Nevada.
• Devils Hole is a tectonic cave developed in the discharge zone of a regional aquifer in south-central Nevada. The walls of this predominantly subaqueous cavern are coated with dense vein calcite. The calcite layers have allowed scientists to derive a 500,000-year record of variations in temperature and other ancient climatic parameters.
• Paleontological and paleogeographic evidence suggests that the Ash Meadows region was once part of an extensive shallow lake and riverine system (Anderson et al. 1998). With the recession of the water table in the late Pleistocene (11,000 ybp), and with the subsequent isolation of spring systems, populations therefore became isolated at different times.
• Ash Meadows endemics like the Devils Hole Pupfish, rely on fossil water stored in underground basins since the end of the last Ice Age. The spring water in Devils Hole is known to be at least 8,000 years old.
• The Devils Hole population (C. diabolis) was first isolated to its present habitat perhaps as long as 10,000 years ago [Riggs et al. Winograd et al. 1992].
• In a move to protect the species, Devils Hole was designated part of the Death Valley National Monument in 1952.
• The land surrounding Devils Hole was purchased from developers, and the 22,000-acre Ash Meadows National Wildlife Refuge was created in 1984.
• This pool is composed of essentially two components including a rock shelf 3.5 x 5 x 0.3 meters deep and a connected deeper section about 3.5 x 17 meters to unknown depth, lying 15 meters deep in a range of low hills in Ash Meadows, Amargosa Township, Nye Co., NV.
• Devils Hole Hills: Elevation from 681 meters to 1316 meters above sea level (635 m difference) Area: 109.3 Ha.
• Devils Hole pupfish occupy the upper 80 feet of the portion of the cavern system open to daylight. About 50% of the population occurs over the small, shallow rock shelf.
• Water temperatures in the breeding and spawning habitats of Devils hole fluctuates between 32 degrees and 36.5 degrees Celsius (based on various studies). These fluctuations depend upon the season, time of day, the amount of direct and/or reflected sunlight reaching the waters surface and the air temperature.
• The 93-degree F (33-degrees Celsius) constant water temperature in which the Devils Hole Pupfish lives within the barren cavern in the Amargosa Valley has been steadily declining in depth.
• The water's diminishing depth means a loss of oxygen, as necessary to life for the fish as it is for humans; and a lowered water level raises its temperature, contributing to algae blooms that crowd out the fish.
• Water-quantity and quality changes following an earthquake can adversely affect sensitive ecosystems, harming the plants and animals that live there. The endangered Devil’s Hole pupfish (Cyprinodon diabolis) has lived for thousands of years in only one pool in Ash Meadows, Nevada, spawning on a single 6 x 13 foot shelf just below the water surface. In 1978, an earthquake in Mexico caused such violent water-level oscillations in Devil’s Hole that algae was scoured from the shallow shelf, and the 2002 Denali Fault earthquake also apparently caused oscillations of 5-6 feet (Jim Roche, National Park Service, written commun., 2002). A persistent drop of water level below the shelf could extinguish the pupfish, whose life span is only a few years. Although court orders and careful management have led to population stability, the existence of the Devils Hole pupfish remains precarious.
• Studies on the reproductive ecology of other pupfish taxa suggest water temperatures in Devils Hole are likely to be near the upper maximum threshold for successful egg production and fry recruitment. These studies also suggest small increases in water temperature on the order of a few degrees may be sufficient to decrease or eliminate successful recruitment of Devils Hole pupfish.
• The primary natural short-term movements of the shallow shelf environment are surface water inflows and earthquake-induced water level fluctuations called “Devils Hole tsunamis” by researchers
• The pupfish's algae food source is limited and easily imbalanced by available sunlight. Owl droppings contribute the most nutrients.

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• In the 1940's Leavitt Hubbs and Robert Rush Miller proposed that Devils Hole, the small spring that held the sole population of Cyprinodon diabolis, be made a separate part of Death Valley National Monument.
• The first underwater exploration of Devils Hole was conducted in June 1950, by members of the National Speleological Society.
• In 1952 President Truman set aside 40 acres (16 hectare) of federal land to safeguard what he called a "peculiar fish.'' Devils Hole became an extension of Death Valley National Monument (now DV National Park), under the American Antiquities Preservation Act, which allows presidents to establish national monuments.
• Devils Hole, the tiniest of federally protected natural areas, is part of the nation's largest national park in the lower 48 states, Death Valley National Park.
• The first underwater population estimate was conducted in November 1954 (approximately 300 fish were counted).
• The Devils Hole pupfish was listed as Endangered on March 11, 1967 with the first listing of endangered fishes in the U.S.
• For more than 50 years, scientists have been trying to save the species, which once numbered more than 500.
• In 1969, the Desert Fishes Council was formed in response to the plight of the small fish.
• In 1972, mostly through the efforts of the Council, the people of the United States brought suit against the land developers and the State of Nevada. The legal battle continued for almost four years and centered around the question of water rights.
• In 1972, a small number of fish were removed from Devil's Hole to a concrete tank near Hoover Dam.
• In June 1976, the United States Supreme Court ruled in favor of the fish. The Court, upholding a lower court order established a minimum water level in Devil's Hole which would insure the continued existence of the pupfish.
• The U.S. Supreme Court ruled that year that the site could be protected, and sided with the fish again in 1976 when developers and farmers challenged conservation efforts.
• In 1981, a few more fish were removed and placed in another concrete tank about a mile distant from Devil's Hole. The management philosophy behind this distribution is that spreading the fish out will minimize the possibility of losing this species due to natural or man-caused disaster.
• Devils Hole pupfish are generally counted 2 times a year (spring and fall counts). 2 to 3 observers record pupfish within the shallow shelf, while scuba divers count the pupfish to a depth of 80 feet within the cavern. Counts during the morning and afternoon are conducted to obtain an average. The spring population is historically lower (up to 250 adult fish), and the fall population is historically higher (up to 500 adult fish).
• Efforts to increase the population of Devils Hole pupfish will continue at the Hoover Dam Refuge, Willow Beach National Fish Hatchery, Point of Rocks Refuge, and the Shark Reef Aquarium at Mandalay Bay Casino and Resort. (6/06)
• Point of Rocks Refuge (Point of Rocks and one near School Springs at Ash Creek Meadow, Nye County Nevada) population is no longer pure Devils Hole pupfish. Ash Meadows pupfish, native to the springs in this area, got into the refuge and have bred with the Devils Hole pupfish creating a hybridized fish.
• On May 2, 2006, hybridized Devils Hole pupfish were successfully moved from the Point of Rocks Refuge to Willow Beach Hatchery and to Shark Reef at Mandalay Bay.
  • Willow Beach Hatchery: 40 fish (20 females, 10 males, and 10 juveniles) (5/2/2006)
  • Shark Reef Aquarium at Mandalay Bay: 40 fish (20, females, 10 males, 10, juveniles) (5/2/2006)
    

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• By a presidential proclamation, Devil's Hole was set aside and annexed to Death Valley National Monument as part of a preservation effort on behalf of the fish in 1952.
• In 1976, the Supreme Court (Cappaert v. United States, 426 U.S. 128 (1976)) ruled that the Devil's Hole Pupfish had prior water rights and that a minimum level must be preserved in the Hole in order to ensure their protection. This decision helped build support for passage of the visionary U.S. environmental legislation of the 1970's, stimulated creation of the Ash Meadows National Wildlife Refuge, assisted in the transformation of Death Valley into a National Park, and was a primary force behind formation of the Desert Fishes Council (begun in November 1969).

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U.S. Fish & Wildlife | National Park Service| Nevada Dept. of Wildlife