Devil’s Hole Pupfish
Tagged: animal, fish, invertebrateCyprinodon diabolis
The Devil’s Hole pupfish gets its name from the freshwater limestone cave pool in which it lives. Its entire life cycle is spent largely within the boundaries of a shelf near the surface of the pool. If conditions on the shelf are less than ideal, the pupfish is in immediate danger. The Devil’s Hole pupfish has been known since 1891. However, for 40 years it was assumed to be a variant of another well-known species, the desert pupfish. In 1930 its distinctive nature was fully realized, and it was named as a separate species. The “devil” that the pupfish bears in its common name is not a reflection of its form or habits, but rather of its natural habitat: Devil’s Hole cave pool in Nye County, Nevada. The narrow but deep dimensions of the pool make diving difficult for those allowed to use it (researchers and others involved in scientific work on the pool and its inhabitants). Devil’s Hole is 55 feet (17 m) long, 10 feet (3 m) wide, and over 300 feet (90 m) deep. The pupfish has been found at depths of up to 80 feet (25 m). However, much of its everyday life is based around a shallow ledge or shelf measuring 18 by 10 feet (5.5 by 3 m). The Devil’s Hole pupfish congregate here to spawn and to feed on the tiny aquatic invertebrates that live and feed on an alga) “mat.”
Life on the Shelf
The Devil’s Hole pupfish lives in precarious conditions, and the Devil’s Hole shelf plays a pivotal role in the survival of the species. As with other species, water level is critical; even a minor drop spells real danger for the pupfish. If the shelf were deeper within Devil’s Hole, then water level fluctuations would present less of a problem. As it is, a decrease in water level of only 39 inches (100 cm) exposes the shallowest area of the shelf and destroys much of the algal growth. As a result, the invertebrate population is reduced, and the fish are deprived of a significant part of their food supply. A further reduction in water level, leading to exposure of the whole ledge, would cause the destruction of spawning sites. The result would be possible extinction if levels remained low for any length of time.
The Pupfish and the Law
In 1952 Devil’s Hole was incorporated into the Death Valley National Monument, offering the cave pool official protection. It took 15 more years for the pupfish to be recognized as an endangered species. However, its newfound legal status, which should have been enough to ensure its continued survival, did not produce the desired results. In what is sometimes reported as a serious error, some of the land in the vicinity of Devil’s Hole (now known as the Ash Meadows National Wildlife Refuge) passed into private ownership. Within a short time wells had been sunk in the area, with the result that water levels in the subterranean aquifers (water-bearing layers of permeable rock, sand, or gravel) supplying Devil’s Hole began to suffer. By 1969, 60 percent of the Devil’s Hole shelf was exposed by the drop in water level, posing a serious threat to the fish. Urgent action was taken. Specimens were transferred to several fishless desert springs, aquarium breeding projects were set up, and a fiberglass ledge with overhead lights was installed at a suitable depth within Devil’s Hole itself. The last measure proved considerably more successful than the other salvage attempts. After several years of further campaigning, and a series of court hearings, the Devil’s Hole pupfish obtained its legal lifeline in 1976. The ruling set out to limit the amount of water that could be pumped from the area. The pupfish has experienced further threats since, but has managed to survive with the help of scientists and conservationists.
Conservation Measures
To check natural population levels, researchers carry out a count at least twice a year, diving 80 feet (25 m) to the shelf known as Anvil Rock. They record every fish encountered during the gradual ascent to the surface. In addition, an above-water count of fish on the shallower ledge is carried out. Depending on the time of year, counts vary from under 200 specimens to over 500. The highest numbers are recorded following the spawning season in the summer; they drop off during the winter when the algal mat dies back, largely due to lack of sunlight. A species “safety net” can be found in three specially built ponds or “refugia.” Each contains subpopulations of pupfish; two of the ponds have about 200 fish, while in the third, breeding has only just begun. As long as conditions in Devil’s Hole remain within certain limits, it would seem that naturally fluctuating population levels may not adversely affect the continued survival of the species.
Devil’s Hole pupfis
Cyprinodon diabolis
- Family: Cyprinodontidae
- World population: About 650
- Distribution: Devil’s Hole, Ash Meadows National Wildlife Refuge, Nye County, Nevada
- Habitat: Largely confined to shallow water over an algae-covered shelf; specimens also found in deeper water down to 80 ft (25 m). Water temperature about 86°F (30°C)
- Size: Length: males 1 in (2.5 cm); females smaller
- form: Relatively large head; dorsal fin set well back on body; lacks pelvic (hip) fins. Males in breeding condition have bluish tinge to body and black edges to the yellowish-golden fins. At other times the body is brown with silvery sides and numerous black specks
- Diet: Small, aquatic invertebrate fauna of shelf’s alga) mat
- Breeding: Eggs laid among algae on the shallow spawning shelf from spring into summer
- Related endangered species: Other Cyprinodonts, including Cachorrito lodero (Cyprinodon beltrani); Leon Springs pupfish (C. bovinus); Comanche Springs pupfish (C. elegans); Perrito de carbonera (C. fontinahs); Cachorrito cangrejero (C. labiosus); large-scale pupfish (C. macrolepis); Cachorrito gigante (C. maya); Cachorrito de mezquital (C. meeki); Cachorrito cabezon (C. pachycephalus); Pecos pupfish (C. pecoensis); Owen’s pupfish (C. radiosus); Cachorrito boxeador (C. simus); Cachorrito de dorsal larga (C. verecundus); and Cachorrito de charco azul (C. veronicae)
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