The Devils Hole pupfish (''Cyprinodon diabolis'') is a
critically endangered
An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
species of the family
Cyprinodontidae
Pupfish are a group of small killifish belonging to ten genus, genera of the family Cyprinodontidae of ray-finned fish. Pupfish are especially noted for being found in extreme and isolated situations. They are primarily found in North America, S ...
(pupfishes) found only in
Devils Hole, a water-filled cavern in the US state of
Nevada
Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
. It was first described as a species in 1930 and is most closely related to ''
C. nevadensis'' and the
Death Valley pupfish (''C. salinus''). 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 . 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 is its lack of pelvic fins. The pupfish consumes 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 and the survivorship from egg to adult is low. Individuals live 10–14 months.
Devils Hole is more than deep, though pupfish are only found in the upper . The water is a constant temperature of and dissolved oxygen levels are low. A small, shallowly submerged rock shelf provides critical feeding and spawning habitat for the pupfish. Nearby agricultural irrigation in the 1960s and 1970s caused the water to drop in Devils Hole, resulting in less and less of the shelf remaining submerged. Several court cases ensued, resulting in the
Supreme Court
In most legal jurisdictions, a supreme court, also known as a court of last resort, apex court, high (or final) court of appeal, and court of final appeal, is the highest court within the hierarchy of courts. Broadly speaking, the decisions of ...
case
''Cappaert v. United States'', which determined that the preservation of Devils Hole as a National Monument in 1952 implicitly included preservation of adequate groundwater to maintain the scientific value of the pool and its fauna. Other threats faced by the species include flash floods, earthquakes, and vandalism.
As its entire native range is a single locality, efforts to create other populations have proceeded since the 1960s and 1970s, most of which have failed. Three refugia were created in 1972, 1973, and 1990, though all were closed by 2007 as a result of maintenance failures, hybridization, and small
founder populations. In the early 2010s, an exact replica of the uppermost of Devils Hole was constructed at Ash Meadows Fish Conservation Facility, which was populated with eggs taken from Devils Hole in winter months when development into adults is unlikely. Efforts to conserve the wild population have included removing sediment from the shallow shelf, adding supplemental food, and installing fences and security cameras to keep unauthorized people away. Conservation efforts have been costly and divisive. During the legal battle over ground water in the 1960s and 1970s, bumper stickers were distributed that read "Kill the Pupfish" or "Save the Pupfish". Some have argued that the species should be allowed to go extinct, while others have said this would be akin to "bombing the
Louvre
The Louvre ( ), or the Louvre Museum ( ), is a national art museum in Paris, France, and one of the most famous museums in the world. It is located on the Rive Droite, Right Bank of the Seine in the city's 1st arrondissement of Paris, 1st arron ...
to make way for a parking lot".
Population counts are conducted twice a year, in the spring and fall, with the fall population usually much larger. Since 1972, population counts have peaked at around 550 individuals. The April 2013 count showed only 35 remaining in the wild, but by September 2022, the count showed a total of 263 observed wild pupfish.
The Devils Hole pupfish has been listed as
endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
by the US federal government since 1967 and
critically endangered
An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
by the
International Union for Conservation of Nature
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...
since 2014.
Taxonomy and evolution
The Devils Hole pupfish was
described as a new species in 1930 by American
ichthyologist
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...
Joseph H. Wales. The
holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
had been collected by Wales and
George S. Myers in March 1930 at
Devils Hole in the US state of Nevada. The
species name
In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
"''diabolis''" was chosen to allude to the type locality of Devils Hole. Both the species name and the location spell "Devils Hole" without an apostrophe, a relic of the "quirks of government cartographers and scientists". According to genetic analysis, the
sister taxon
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
of the Devils Hole pupfish is ''
Cyprinodon nevadensis''. Along with the
Death Valley pupfish (''C. salinus''), the three
Amargosa River basin species form a clade.
The age of the species is subject to considerable debate, with analyses recovering starkly different figures. Devils Hole was formed around 60,000 years ago, with some researchers assuming the pupfish has existed in isolation for 10,000–20,000 years. How it colonized Devils Hole is unknown; hypotheses include arriving via subterranean waters or over dry land. As Native Americans used pupfish species as food, it has been speculated that they introduced the pupfish to Devils Hole, intentionally or not. Its divergence from a common ancestor with ''C. nevadensis mionectes'' was estimated at 217–2530 years in one study.
Two studies, each based on independent genetic datasets, estimated that this species may have first colonized the hole within the past 1,000 years, but another suggested the species is as old as 60,000 years.
These estimates depend heavily on knowledge of the mutation rate in this species, which is unknown, but is predicted to be one of the highest for any vertebrate due to its small population size.
Description

The Devils Hole pupfish is the smallest
pupfish species in the genus ''
Cyprinodon
''Cyprinodon'' is a genus of pupfishes found in waters that range from Fresh water, fresh to hypersaline. The genus is primarily found in Mexico, the Caribbean Islands and southern United States (Arizona, California, Florida, Nevada, New Mexico, ...
'',
with lengths up to .
[ The average length is .] Males and females differ in coloration. Males are overall dark brown with metallic blue on their sides. The margins of all fins are black, and the back has golden iridescence. Iridescence is particularly pronounced on the opercles (gill covers) which have a violet sheen on their posterior side. The iris is blue and also iridescent. Females and young are more yellow in color than the males. Females have yellowish-brown backs, and the margins of their pectoral and caudal fins are yellow, not black. The dorsal fin has a black margin like the males, however. Females' opercles are metallic green, and their eyes are tinted metallic blue. The young are overall colored as the females, though they have a faint vertical bar on their sides.
Individuals lack pelvic fin
Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...
s, though have been observed to grow them when raised in lower temperatures in captivity. Its dorsal fin
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...
has twelve rays, while each pectoral fin has seventeen rays. The caudal fin is convex in appearance and has twenty-eight rays, curving outward at the margin. Its lateral series (the number of scales from the back end of the opercle to the beginning of the tail) is twenty-seven scales. The scales are ctenoid, or toothed, on the outer margin.
Biology and ecology
The Devils Hole pupfish consumes a variety of food items representing nearly all possible food resources in Devils Hole. Its food resources include inorganic particulate matter; the algae ''Spirogyra
''Spirogyra'' (common names include water silk, mermaid's tresses, and blanket weed) is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is charact ...
'' and diatom
A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...
s; the freshwater crustaceans '' Hyalella azteca'' and ostracod
Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...
s; protozoa
Protozoa (: protozoan or protozoon; alternative plural: protozoans) are a polyphyletic group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic debris. Historically ...
; the beetle '' Stenelmis calida''; the flatworm '' Girardia dorotocephala''; and the freshwater snails '' Tryonia''. The consumption of the various food resources varies seasonally, though inorganic particulate matter had a high frequency of occurrence in stomach contents year-round in one study. The inorganic particulate matter consists of primarily travertine, a form of limestone. The three most common food items for each season by frequency of occurrence were:
* Spring (March through May): inorganic particulate matter (83%), diatoms (75%), and ''Spirogyra'' (58%)
* Summer (June through August): inorganic particulate matter (79%), ''Spirogyra'' (46%), and diatoms (46%)
* Autumn (September through November): inorganic particulate matter (95%), ''Spirogyra'' (74%), and ''Hyalella azteca'' (33%)
* Winter (December through February): inorganic particulate matter (100%), diatoms (91%), and ostracods (45%)
As ''Spirogyra'' was mostly found undigested in the stomach, the authors hypothesized that it was not important as a food resource, but rather as a foraging substrate. The inorganic particulate matter was thought to be incidentally consumed as well as a result of the fish's foraging strategy of bottom feeding and surface feeding.
Predators of the Devils Hole pupfish include the diving beetle
The Dytiscidae, from the Ancient Greek word δυτικός (''dystikos''), meaning "able to dive", are the predaceous diving beetles, a Family (biology), family of water beetles. They occur in virtually any freshwater habitat around the world, bu ...
species '' Neoclypeodytes cinctellus'', which consumes its eggs and juveniles. ''N. cinctellus'' likely also preys on some of the same invertebrates as does the Devils Hole pupfish, meaning that it is a competitor as well as a predator. The diving beetle only recently became part of the ecosystem, and was first documented at Devils Hole in 1999 or 2000.
Although spawning
Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...
year-round, spawning peaks from mid-February to mid-May with a smaller peak from July to September. Devils Hole pupfish females have low fecundity
Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the capability to produc ...
, which is the capacity to create offspring. The average female may only produce four or five mature ova (egg cells) each breeding season. Mature ova represent 10–20% of the total number of ova produced. During each spawn, a mature female is thought to produce only a single egg, which are only in diameter. In addition to its low fecundity, eggs have low hatching success and juveniles have low rates of survival. Individuals have a lifespan of 10–14 months.
Because the rock shelf upon which the fish feed and breed is susceptible to seismic activity, specialized behavior mitigates the impact of earthquakes. When a disturbance such as an earthquake occurs, it causes the fish to flee ''en masse'' into the depths, and begin a spawning event that may be out of season. During spawning brought upon by a disturbance, several males chase lone females until they become receptive, at which point the female allows one of the males to swim next to her. The female then lays an egg that the male immediately fertilizes.
The Devils Hole pupfish has daily and seasonal movement within the Hole. Around midday, when incoming sunlight is at its maximum intensity on the shallow shelf, the number of fish on the shelf decreases. This tendency to leave the shelf at midday is most pronounced April through September. From December to March, when the shallow shelf receives little if any direct sunlight at midday, the number of fish on the shelf increases as the day advances. In the summer months when the shelf receives the most sunlight, fish are overall less likely to use the shallow shelf.
Having adapted to an environment with low oxygen saturation
Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is Dissolution (chemistry), dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the g ...
, the Devils Hole pupfish has developed a behavior known as "paradoxical anaerobism". The fish enters a state of torpor
Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the ti ...
, and has been known to forego breathing oxygen for up to two hours. As a byproduct of this alternate respiration method, the fish produces ethanol
Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...
.
Habitat
Devils Hole and the pupfish are located in the Amargosa Desert ecosystem, in the Amargosa Valley
The Amargosa Valley is the valley through which the Amargosa River flows south, in Nye County, southwestern Nevada and Inyo County in the state of California
California () is a U.S. state, state in the Western United States that lies ...
, of southwestern Nevada
Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
, US, east of Death Valley
Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. It is thought to be the Highest temperature recorded on Earth, hottest place on Earth during summer.
Death Valley's Badwat ...
and the Funeral Mountains and Amargosa Range. The Amargosa River is part of Devils Hole and the region's aquifer
An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...
hydrology. Devils Hole is a water-filled cavern extending into a hillside. It is at an elevation of above sea level and the water is a constant temperature of . The surface area of Devils Hole is about 22 m long by 3.5 m wide (72 ft long by 11.5 ft wide). Its depth is at least . Devils Hole "may be the smallest habitat in the world containing the entire population of a vertebrate species". Approximately deep on one end of Devils Hole is a small rock shelf of . The dissolved oxygen
Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It can ...
of the water is 2.5–3.0 ppm up to around in depth, though the shallow shelf can have dissolved oxygen levels as high as 6.0–7.0 ppm in June and July.
Although pupfish have been found as deep as , their numbers are most dense above depths of . They depend on the shallow shelf for spawning
Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...
as well as for much of their diet which primarily consists of diatoms
A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...
. Natural threats from flash floods to earthquakes
An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they c ...
have been known to disrupt this fragile ecosystem, but in the 1960s and 1970s, the major threat was groundwater depletion due to agricultural irrigation
Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...
.
Research indicates that the annual population fluctuation is in response to the amount of algae on the shallow shelf, which is dependent on incoming solar radiation and nutrient levels. Nutrient availability may peak when the cave is used by barn owl
The barn owls, owls in the genus '' Tyto'', are the most widely distributed genus of owls in the world. They are medium-sized owls with large heads and characteristic heart-shaped faces. They have long, strong legs with powerful talons. The ter ...
s as a roosting or nesting site, as their nutrient-rich pellets fall into the water.
Conservation and status
Threats
The Devils Hole pupfish species is limited to a single site and highly susceptible to disturbance. In the 1970s, the species was threatened with groundwater depletion, as the withdrawal of groundwater lowered the water level of Devils Hole and limited their ability to spawn on the shallow shelf. After the groundwater withdrawal was limited, its population rebounded, but experienced a second decline from 1995 onward. The reasons for the second decline are unknown, but inbreeding depression
Inbreeding depression is the reduced biological fitness caused by loss of genetic diversity as a consequence of inbreeding, the breeding of individuals closely related genetically. This loss of genetic diversity results from small population siz ...
, the loss of a prey species, changing algal and microbial communities, or shifting sediment dynamics have been hypothesized as potential factors. It could face threats in the future relating to climate change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
, as warming temperatures in the area are predicted to shorten the period of optimum recruitment
Recruitment is #Process, the overall process of identifying, sourcing, screening, shortlisting, and interviewing candidates for Job (role), jobs (either permanent or temporary) within an organization. Recruitment also is the process involved in ...
, or the time when the next generation is produced and matures.
Large-scale earthquakes, such as the 2012 Guerrero–Oaxaca earthquake, the 2018 Gulf of Alaska earthquake and the 2019 Ridgecrest earthquakes, have caused standing waves known as seiche
A seiche ( ) is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, swimming pools, bays, harbors, caves, and seas. The key requirement for formatio ...
s in Devils Hole, which can lead to an unseasonal spawning event due to the disruption of the pupfishes' environment. The waves caused by earthquakes can scour the algae from the rocks (as well as eggs and larvae), affecting the food supply and spawning grounds. Flash floods also disrupt the algae via debris swept into Devils Hole.
In addition to the indirect threat of groundwater depletion, human actions can impact the pupfish in other ways as well. A 2004 flash flood swept scientific monitoring equipment into Devils Hole, causing the deaths of an estimated eighty pupfish. In April 2016, three men broke into the Devils Hole protected area, destroying scientific equipment and wading onto the shallow shelf of Devils Hole, smashing pupfish eggs and larvae, as well as vomiting into the water.
Isolation over the course of thousands of years has led the Devils Hole pupfish to become what are believed to be one of the most inbred vertebrates on Earth, and the resulting high mutation load and genetic instability remains a potential long-term threat to the species as a whole.
Status designations and legal action
In the late 1940s, ichthyologist Carl Leavitt Hubbs
Carl Leavitt Hubbs (October 19, 1894 – June 30, 1979) was an American ichthyologist.
Biography
Early life
Carl Leavitt Hubbs was born in Williams, Arizona, to Charles Leavitt and Elizabeth () Hubbs. His father had a wide variety of jobs (far ...
began campaigning for legal protection for Devils Hole and the pupfish. This led to President Harry S. Truman
Harry S. Truman (May 8, 1884December 26, 1972) was the 33rd president of the United States, serving from 1945 to 1953. As the 34th vice president in 1945, he assumed the presidency upon the death of Franklin D. Roosevelt that year. Subsequen ...
issuing a proclamation in 1952 that made Devils Hole part of Death Valley National Monument (now National Park). In 1956, the United States Geological Survey
The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...
(USGS) installed the first water level recorder. The fish was officially listed as an endangered species in 1967,[ making it one of the first species protected under the ]Endangered Species Act
The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...
.
In 1967, Spring Meadows, Inc. began purchasing large tracts of Ash Meadows, much from the Bureau of Land Management
The Bureau of Land Management (BLM) is an agency within the United States Department of the Interior responsible for administering federal lands, U.S. federal lands. Headquartered in Washington, D.C., the BLM oversees more than of land, or one ...
, in anticipation of developing of irrigated cropland. Many wells were drilled from 1967–1970, causing a decline of the water at Devils Hole by 1968. The level continued to drop through 1972, causing alarm as a 1969 study had determined that the shallow shelf was virtually the only feeding and spawning habitat available to the fish. Conservationists and public opinion began to rally for preservation of the pupfish, with a 1970 issue of the magazine ''Cry California'' stating that allowing it to go extinct would be "comparable to bombing the Louvre
The Louvre ( ), or the Louvre Museum ( ), is a national art museum in Paris, France, and one of the most famous museums in the world. It is located on the Rive Droite, Right Bank of the Seine in the city's 1st arrondissement of Paris, 1st arron ...
to make way for a parking lot". Two organizations were formed in support of the species: the Desert Fishes Council and the Desert Pupfish Task Force.
In 1970, the USGS began a study to determine why the water level was receding at Devils Hole, concluding that a substantial withdrawal of groundwater would negatively affect the water level, and thus, pupfish habitat. In August 1971, the U. S. Department of Justice filed a complaint on behalf of the Department of the Interior, seeking to stop Spring Meadows from using three wells identified as having the greatest impact on Devils Hole. The basis for the argument was that when Devils Hole became part of a National Monument in 1952, sufficient water was thus reserved "to serve the requirements and purposes of the monument". Later that month, Spring Meadows and the federal government made an agreement that they would cease operation of the three identified wells, and not increase withdrawal at their other wells to compensate. Though the water level briefly rose, it once again entered a decline, exposing more than half the shallow shelf by summer 1972. This caused the government to reactivate the suit in 1972. Now, they wanted Spring Meadows to cease using any wells within of Devils Hole for any non-domestic purpose based on the implied reservation doctrine established in '' Winters v. United States'' (1908). An injunction in favor of the government was issued in June 1973, which was appealed to the United States Court of Appeals for the Ninth Circuit
The United States Court of Appeals for the Ninth Circuit (in case citations, 9th Cir.) is the U.S. federal court of appeals that has appellate jurisdiction over the U.S. district courts for the following federal judicial districts:
* Distric ...
(upheld in 1974) and the Supreme Court
In most legal jurisdictions, a supreme court, also known as a court of last resort, apex court, high (or final) court of appeal, and court of final appeal, is the highest court within the hierarchy of courts. Broadly speaking, the decisions of ...
.
In the case '' Cappaert vs. U.S.'', decided in 1976, the Supreme Court upheld the injunction and determined that the district court should set the minimum water level necessary to ensure pupfish survival. The Court stated that by making Devils Hole part of a National Monument, the groundwater necessary to sustain the pupfish was implicitly reserved. In 1977 the district court determined that the water level minimum would be below a reference point on the wall.
In 1980, the U.S. Fish and Wildlife Service (USFWS) designated about as essential habitat where the groundwater most influenced the water level in the Hole. One of the identified goals of the recovery plan was to maintain the aquifer at such levels that the population fluctuates from 300 in winter to 700–900 in late summer. The water source for Devils Hole pupfish were now protected from industrial use, but the rest of Ash Meadows was unprotected. When the USFWS declined to purchase the land from Cappaert Enterprises, Ash Meadows was sold in 1980 to a property development company, Preferred Equities Corporation, who acquired additional nearby land with the intention of creating 33,636 residential parcels altogether. As the original injunction limited water with exception to domestic purposes, it was unclear if residents of the proposed subdivision would have to limit water usage in respect to the water level of Devils Hole. In 1982, Secretary of the Interior James Watt
James Watt (; 30 January 1736 (19 January 1736 OS) – 25 August 1819) was a Scottish inventor, mechanical engineer, and chemist who improved on Thomas Newcomen's 1712 Newcomen steam engine with his Watt steam engine in 1776, which was f ...
approved the emergency listing of two more Ash Meadows fish, the Ash Meadows pupfish (''Cyprinodon nevadensis mionectes'') and the Ash Meadows speckled dace (''Rhinichthys osculus nevadensis''). Further development by Preferred Equities would therefore almost certainly violate the Endangered Species Act. After protracted negotiations, The Nature Conservancy
The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia, United States. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US.
Founded in ...
(a nonprofit) was able to purchase Ash Meadows for $5.5 million in February 1984, with reimbursement from the U.S. Federal Government of $5 million. By June 1984, Ash Meadows National Wildlife Refuge was established, as The Nature Conservancy transferred the property to the government. By 1986, a recovery plan was drafted for all of Ash Meadows, encompassing Devils Hole.
As of 2014, Devils Hole pupfish is evaluated as a critically endangered
An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
species by the IUCN
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
. The species meets the criteria for this designation due to its extremely small extent of occurrence and area of occupancy, both of which are less than . Additionally, the species is found in a single locality and has a very small population, often with fewer than 100 mature individuals. In the state of Nevada, it is considered a protected species that is also endangered.
Recovery actions
In the wild
Shortly after 1956, a locked gate was installed in a rock crevice of Devils Hole to limit public access to the site. By 1970, as the shallow shelf was exposed by groundwater depletion, an artificial shelf was installed at Devils Hole. It was never used by the fish. In 2005, of sediment was removed from the shallow shelf to encourage feeding and spawning. While the number of larvae appeared to increase as a result, the population still experienced a net decline over the following year. In January 2006, biologists began supplementing the fish's food supply in response to observations of poor health and malnourishment. After vandalism resulted in the death of a pupfish in 2016, the National Park Service added additional barbed wire to the top of the fences surrounding Devils Hole, also installing more motion sensors and video cameras.
''Ex situ'' conservation
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
California State University, Fresno (Fresno State) is a public university in Fresno, California, United States. It is part of the California State University system. The university had a fall 2020 enrollment of 25,341 students. It offers 60 ba ...
, 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
The Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado, Black Canyon of the Colorado River (U.S.), Colorado River, on the border between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, d ...
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.
Historical attempts to maintain the refugia populations through traditional methods has been largely ineffective, blamed on the small founder population size of each refugium 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
Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions.
Local extinctions mark a chan ...
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
The Las Vegas Strip is a stretch of Las Vegas Boulevard in Clark County, Nevada, that is known for its concentration of resort hotels and casinos. The Strip, as it is known, is about long, and is immediately south of the Las Vegas city limits ...
casino aquarium at Mandalay Bay
Mandalay Bay is a 43-story luxury resort and casino at the south end of the Las Vegas Strip in Paradise, Nevada. It is owned by Vici Properties and operated by MGM Resorts International. It was developed by Circus Circus Enterprises and complete ...
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
The Willow Beach National Fish Hatchery is administered by the U.S. Fish and Wildlife Service, located approximately 45 miles (72.4 km) South East of Las Vegas, Nevada, in Mohave County, Arizona on the Arizona side of the Colorado River tw ...
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
Leukemia ( also spelled leukaemia; pronounced ) is a group of blood cancers that usually begin in the bone marrow and produce high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or '' ...
.
In the early 2010s, a full-scale replica of the upper of Devils Hole was built at the new Ash Meadows Fish Conservation Facility (AMFCF), resulting in a tank. Located less than a mile away (), this refuge closely 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 cooler than that of Devils Hole and the dissolved oxygen content is doubled in attempts to reduce thermal and respiratory stress on the fish.
The population of Devils Hole pupfish at AMFCF was created by taking eggs from Devils Hole. However, eggs are only removed at times of the year when it is unlikely that they would develop into mature adults, such as in the winter. It is thought that egg removal during this time would therefore have the least impact on the population size at Devils Hole. When transferred to AMFCF, the eggs are exposed to anti-fungal, anti-bacterial, and anti-parasite treatments. They are reared in the aquarium until adulthood, at which point they are transferred to the large refuge tank. This procedure is also followed for eggs laid in the refuge tank. While efforts have been made to remove the predaceous beetle ''Neoclypeodytes cinctellus'' from the captive population's tank to lessen its depredation on eggs, it has not been removed from Devils Hole. It is unknown how removal of the species could affect the Devils Hole ecosystem, and the number of beetles in Devils Hole is less than in the tank hosting the captive population.
As of 2021, the efforts of the Ash Meadows Fish Conservation Facility have been considered "very successful" in maintaining a refuge population. At least fifty captive fish populated the refuge as of 2019, with an additional 10–20 in propagation tanks.
Costs and public opinion
Millions of dollars have been spent conserving the Devils Hole Pupfish. The construction of the Ash Meadows Fish Conservation Facility alone, which opened in 2013, was estimated to cost $4.5 million. Conservation efforts from January 2006 to May 2007 were $750,000. The legal case over the rights to extract groundwater concluded that the Cappaert family, who invested $7 million into opening a ranch in the area, could no longer withdraw the same amount of water. The Cappaert family's attorney decried that the Supreme Court had chosen the interests of a fish over people, and a newspaper editor from nearby Pahrump threatened to dump a pesticide
Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...
into Devils Hole to kill them all. In response to bumper stickers that read "Save the Pupfish" distributed by the Desert Fishes Council, Nye County Commissioner Robert Rudd produced bumper stickers that said "Kill the Pupfish". The Cappaert family sold the ranch in the late 1970s.
Population trends
Population surveys of the Devils Hole pupfish began in 1972. Population counts since then have been conducted using the same methods, with scuba diving
Scuba diving is a Diving mode, mode of underwater diving whereby divers use Scuba set, breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The word ''scub ...
researchers counting fish starting at depths of while researchers above the water count the individuals on the shallow shelf. Surveys are carried out twice a year, once during the spring season and once during fall.
From 1970 through 1996, the average population was 324.[ Population highs were recorded in 1980, 1990, and 1995 at counts of 541–548 individuals.] Since 2005, the population at Devils Hole has been below 200 individuals, although the population fluctuates depending on the season
A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's axial tilt, tilted orbit around the Sun. In temperat ...
. Low algae
Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
growth and other winter conditions cause spring populations to be 35–65% of the autumn population.[ The reasons for the decline of the population are unclear.] A 2014 study ascertained that the Devils Hole pupfish had a 26–33% chance of becoming extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
in the next twenty years.
In November 2005, divers counted just 84 individuals in the Devils Hole population, the same as the spring population, despite observations of egg-laying and juvenile fish during the summer. In 2007, between 38 and 42 fish were left in Devils Hole.
The pupfish count rose in the autumn of 2008 to 126, the first steady increase in more than 10 years. As of April 2013 U.S. Fish and Wildlife reported only 35 fish remain in their natural habitat, but increased to 92 when measured again in 2014. As of spring 2016, a periodic count found 115 of the fish living in the waters. In spring 2019, the pupfish population reached 136, the highest springtime population since 2003.
Population counts were suspended in 2020 due to the COVID-19 pandemic
The COVID-19 pandemic (also known as the coronavirus pandemic and COVID pandemic), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began with an disease outbreak, outbreak of COVID-19 in Wuhan, China, in December ...
; however, egg collection for ''ex situ'' cultivation continued. Observers noted encouraging signs of population growth, and during the next count in April 2022, 175 pupfish were observed. The population has continued to grow, with 263 observed pupfish in September 2022. In spring 2024 the population was 191 individuals, the highest springtime count in 25 years. Increased nutrients for algae growth, swept into Devils Hole by runoff from Hurricane Hilary in 2023, may have contributed to the pupfish's proliferation.
In spring 2025, the population declined to only 38 individuals, prompting the introduction, for the first time, of 19 captive-bred fish. Substantial swings in population size are considered not untypical for species in the genus.
See also
Many of the various surviving local ''Cyprinodon
''Cyprinodon'' is a genus of pupfishes found in waters that range from Fresh water, fresh to hypersaline. The genus is primarily found in Mexico, the Caribbean Islands and southern United States (Arizona, California, Florida, Nevada, New Mexico, ...
'' species and subspecies (pupfish), including the Devils Hole pupfish, are on the IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...
of threatened species
A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...
:
* Ash Meadows pupfish, ''Cyprinodon nevadensis mionectes''
* Amargosa pupfish, ''Cyprinodon nevadensis amargosae''
* Death Valley pupfish, Salt Creek pupfish ''Cyprinodon salinus salinus''
* Cottonball Marsh pupfish, ''Cyprinodon salinus milleri''
* Shoshone pupfish, ''Cyprinodon nevadensis shoshone''
* Saratoga Spring pupfish, ''Cyprinodon nevadensis nevadensis''
* Tecopa pupfish, ''Cyprinodon nevadensis calidae'' (extinct)
* Desert pupfish
The desert pupfish (''Cyprinodon macularius'') is a rare species of teleost, bony fish in the family Cyprinodontidae. It is a small fish, typically less than 7.62 cm (3 in) in length. Males are generally larger than females, and have br ...
, ''Cyprinodon macularius''
* Owens pupfish, ''Cyprinodon radiosus''
References
External links
Desert Fishes Council
"Attack of the Mutant Pupfish"
a ''Wired
Wired may refer to:
Arts, entertainment, and media Music
* ''Wired'' (Jeff Beck album), 1976
* ''Wired'' (Hugh Cornwell album), 1993
* ''Wired'' (Mallory Knox album), 2017
* "Wired", a song by Prism from their album '' Beat Street''
* "Wired ...
'' article by Hillary Rosner
PBS video segment on the Devils Hole Pupfish
* by CBS Sunday Morning
{{Authority control
Amargosa Desert
Articles containing video clips
Cave fish
Critically endangered fauna of the United States
Cyprinodon
Desert National Wildlife Refuge Complex
Endemic fauna of Nevada
Fauna of the Mojave Desert
Taxa named by Joseph Howe Wales
Fish described in 1930
Fish of the Western United States
Freshwater fish of the United States
Natural history of Nye County, Nevada