This unusual fish species is considered to be rarer than the giant panda. They inhabit Devil’s Hole, a place located in Death Valley, California, USA, known for its extremely harsh climate.
Previously, giant pandas were listed as endangered. However, thanks to conservation efforts, the number of wild pandas has recently surpassed 1,800 individuals. Few people know that there is a fish species even more precious than pandas, with a population of only around 200. What is this fish?
Unique Habitat
Devil’s Hole is located within a secluded area of Death Valley National Park, straddling the borders of California and Nevada in the USA. According to Wikipedia, Devil’s Hole is a geothermal pool in a limestone cave in the Amargosa Desert within Nevada’s Amargosa Valley, situated east of the Amargosa Range and the 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 measures approximately 22 meters long and 3.5 meters wide. At one end of Devil’s Hole, there is a small rock ledge measuring 3.5 x 5 meters and a depth of about 0.3 meters. The dissolved oxygen levels in the water range from 2.5 to 3.0 ppm, reaching up to about 22 meters deep, although the shallow ledge can have dissolved oxygen levels as high as 6.0 to 7.0 ppm during June and July.
Within Devil’s Hole resides a population of fish known as the Devil’s Hole pupfish. The Devil’s Hole pupfish, also referred to as the Devil’s Hole fish, was first discovered in 1930 by American ichthyologist Joseph H. Wales. They are closely related to the Amargosa pupfish and the Salt Creek pupfish.
The Devil’s Hole pupfish is a small fish, reaching a maximum length of 30 mm. Their coloration varies depending on age and gender. Specifically, males are bright blue while females are bright yellow. The edges of all fins are black, and the back is golden-yellow. The iridescence is particularly pronounced on the eyelid (the operculum) which has a purple hue on its reverse side. The pupils are blue and also have an iridescent quality.
Females and juveniles are yellower than males. Females have a brownish-yellow back, with the edges of their pectoral and caudal fins being yellow, not black. However, the dorsal fin has a black edge similar to males. The brain of females is metallic green, and their eyes are metallic blue. Juveniles resemble females in overall coloration, although they have a faint vertical stripe on either side. This species lacks pelvic fins. Their dorsal fin comprises twelve rays, while each pectoral fin has seventeen rays. The caudal fin is convex and has twenty-eight rays, curving outward at the edges. Its lateral line (the number of scales from the head to the tail) consists of 27 scales, which have serrated edges.
The diet of the Devil’s Hole pupfish changes throughout the year, consisting of various beetles, snails, algae, and freshwater crustaceans. The consumption of different food sources varies seasonally, although inorganic particulates frequently appear in their stomachs. Scientists believe that these inorganic particulates are consumed randomly as well as a result of the pupfish’s foraging strategy, which involves feeding at the bottom and on the surface.
They reproduce year-round, typically in spring and autumn. The peak breeding period is from mid-February to mid-May. Female Devil’s Hole pupfish have very low reproductive capacity. Females can only produce four or five mature eggs each breeding season. Mature eggs account for 10-20% of the total eggs produced.
During each spawning event, a mature female lays a single egg, allowing only one male to swim alongside her. After she lays the egg, the male fertilizes 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 and are often preyed upon by the beetle Neoclypeodytes cinctellus, which feeds on their eggs and juveniles. This beetle was first recognized as part of the ecosystem of Devil’s Hole in 1999 or 2000.
Devil’s Hole has a depth of over 130 meters, and the Devil’s Hole pupfish live at a depth of 24 meters. According to scientific research, the Devil’s Hole pupfish has inhabited Devil’s Hole for approximately 60,000 years. It is believed that Devil’s Hole was formed around 500,000 years ago. Experts speculate that the formation of Devil’s Hole was caused by an earthquake. As for how the Devil’s Hole pupfish came to inhabit it, scientists hypothesize that they arrived through subterranean water.
Facing the Threat of Extinction
Since the late 1940s, hydrologist Carl Leavitt Hubbs has initiated legal protection efforts for the pupfish in Devil’s Hole. 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.
The reason is due to a large number of wells being drilled in the area near Devil’s Hole. This led to a significant decline in the Devil’s Hole pupfish population in the 1970s as the groundwater in Devil’s Hole was rapidly depleted, limiting their reproductive capacity. After groundwater levels increased, the population recovered, but it abruptly declined again in 1995. The cause of this second decline was confirmed by scientists to be inbreeding, changes in algal and microbial populations, or sediment alterations.
In addition to the indirect threats posed by groundwater depletion, human actions can also impact the pupfish in various ways. For instance, 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 Devil’s Hole pupfish was classified by the IUCN (International Union for Conservation of Nature) as critically endangered. In Nevada, the Devil’s Hole pupfish is considered a protected endangered species.
In April 2016, three intoxicated men broke into the protected area of Devil’s Hole, vandalized scientific equipment, waded into the shallow ledge, smashed eggs and larvae of the pupfish, and even vomited into the water. This incident reduced the pupfish population to just 37 individuals. Following this act of vandalism, the U.S. National Park Service added barbed wire to previously erected fences and installed surveillance cameras.
From Crisis to Hope
Additionally, scientists noted that earthquakes in Guerrero – Oaxaca in 2012, the Alaska Bay earthquake in 2018, and the Ridgecrest earthquake in 2019 caused seismic waves in Devil’s Hole, potentially disrupting the reproduction of the pupfish.
American scientists have made significant efforts to conserve the Devil’s Hole pupfish. They have attempted to relocate them to safer areas, but most efforts have failed. In early 2010, they created a replica similar to Devil’s Hole to conserve this fish 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 USD (over 90 billion VND). This has caused significant controversy 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 increased to 175 individuals.
