This strange fish species is considered to be even rarer than the giant panda. They inhabit Devil’s Hole, a location within Death Valley in the United States, known for its extremely harsh climate.
Previously, giant pandas were listed as endangered species. However, thanks to conservation efforts, the number of pandas in the wild has recently surpassed 1,800 individuals. Few know that there exists a fish species even rarer than pandas, with a population of just around 200 individuals. What type of fish is it?
Unique Habitat
Located in a place known as Devil’s Hole, this unique habitat is part of Death Valley National Park, situated between California and Nevada in the United States. According to Wikipedia, Devil’s Hole is a geothermal pool found in a limestone cave in the Amargosa Desert within Nevada’s Amargosa Valley, east of the Amargosa Range and Funeral Mountains from Death Valley. It sits at an elevation of 730 meters above sea level, with a constant water temperature of 33 degrees Celsius.
The surface area of Devil’s Hole is approximately 22 meters long and 3.5 meters wide. At one end, it reaches a depth of about 0.3 meters, leading to a small rocky shelf measuring 3.5 x 5 meters. The dissolved oxygen levels in the water range from 2.5–3.0 ppm up to about 22 meters, although the shallow shelf may have oxygen levels as high as 6.0–7.0 ppm during June and July.
Within Devil’s Hole resides a population of fish known as Devil’s Hole pupfish. This species, also referred to as the devil pupfish, was first discovered in 1930 by American ichthyologist Joseph H. Wales. They are closely related to the Amargosa pupfish and Salt Creek pupfish.
The Devil’s Hole pupfish is a small species, reaching a maximum length of 30 mm. Their coloration varies based on age and sex; males are bright blue while females are bright yellow. The edges of all their fins are black, and their backs are a metallic gold. The metallic sheen is particularly pronounced on their operculum (gill cover), which has a purple tint on the rear. Their irises are blue with a metallic sheen as well.
Females and juveniles are more yellow than males. Females have a brownish-yellow back, with the edges of their pectoral and caudal fins being yellow rather than black. However, their dorsal fin has black margins similar to males. The brains of females are metallic green, and their eyes have a metallic hue. Juveniles have an overall coloration similar to females, although they possess a faint vertical stripe on each side. This species lacks pelvic fins, has twelve rays in its dorsal fin, and seventeen rays in each pectoral fin. The tail is convex with twenty-eight rays, curving outward at the edges. Its lateral line consists of 27 scales, which have a serrated or spiny edge.
The diet of the Devil’s Hole pupfish varies throughout the year, consisting of beetles, snails, algae, and freshwater crustaceans. The consumption of different food sources changes with the seasons, although inorganic particulate matter frequently appears in their stomachs. Scientists believe that these particulates are likely consumed both randomly and as a result of the fish’s bottom-feeding strategy.
They reproduce year-round, typically during spring and fall, with peak breeding occurring from mid-February to mid-May. Female Devil’s Hole pupfish have very low reproductive potential. A female can only produce four or five mature eggs each breeding season. The mature eggs account for 10-20% of the total number of eggs produced.
During each spawning event, a mature female lays a single egg, accepting only one male to swim beside her. After she lays her egg, the male will fertilize it immediately. The eggs of the Devil’s Hole pupfish measure only 1 mm in diameter and have a very low survival rate. Devil’s Hole pupfish can live from 10 to 14 months, often falling prey to the diving beetle Neoclypeodytes cinctellus, which consumes their eggs and juveniles. This beetle was first reported in the ecosystem of Devil’s Hole in 1999 or 2000.
Devil’s Hole is over 130 meters deep, and the pupfish inhabit a depth of 24 meters. According to scientific research, Devil’s Hole pupfish have been living in this environment for approximately 60,000 years. Reports suggest that Devil’s Hole was formed around 500,000 years ago. Experts speculate that earthquakes caused its formation, while scientists hypothesize that pupfish may have reached Devil’s Hole through subterranean waterways.
Facing Extinction
Since the late 1940s, ichthyologist Carl Leavitt Hubbs has advocated for legal protection for the Devil’s Hole pupfish. In 1967, the Devil’s Hole pupfish was officially listed as an endangered species, becoming one of the first species protected under the Endangered Species Act.
This was primarily due to a large number of wells being drilled in the area surrounding Devil’s Hole. This led to a drastic decline in the pupfish population in the 1970s because the groundwater in Devil’s Hole was rapidly extracted, limiting their breeding capacity. After groundwater levels increased, the population rebounded, only to suddenly drop again in 1995. The cause of this second decline has been confirmed by scientists as inbreeding, changes in algal and microbial populations, or sediment shifts.
In addition to the indirect threats from groundwater depletion, human actions can also impact the pupfish in various ways. For example, a flash flood in 2004 swept scientific monitoring equipment into Devil’s Hole, resulting in the estimated death of around 80 pupfish. As of 2014, the IUCN (International Union for Conservation of Nature) classified the Devil’s Hole pupfish as critically endangered. In Nevada, the pupfish is considered a protected species at risk of extinction.
In April 2016, three intoxicated men trespassed into the protected area of Devil’s Hole, damaging scientific equipment and wading onto the shallow shelf, breaking eggs and larvae of the pupfish, as well as vomiting into the water. This incident reduced the pupfish population to just 37 individuals. Following the vandalism, the U.S. National Park Service reinforced the previously erected fence with barbed wire and installed surveillance cameras.
From Crisis to Hope
Additionally, scientists reported that the Guerrero–Oaxaca earthquakes in 2012, the Alaska Gulf earthquake in 2018, and the Ridgecrest earthquake in 2019 caused seismic waves in Devil’s Hole, potentially disrupting the reproductive cycles of the pupfish.
American scientists have made significant efforts to conserve the Devil’s Hole pupfish. They attempted to relocate them to safer locations, but most efforts were unsuccessful. In early 2010, they created a replica similar to Devil’s Hole to conserve the species at the Ash Meadows Fish Conservation Facility (AMFCF).
Millions of dollars have been spent on the conservation of the Devil’s Hole pupfish, with estimates reaching up to $4.5 million (over 90 billion VND). This expenditure has sparked considerable debate due to the high costs involved. Fortunately, the efforts of scientists have paid off; as of April 2022, the population of Devil’s Hole pupfish in Devil’s Hole has risen to 175 individuals.
