LAS VEGAS (KLAS) — Staff from Death Valley National Park’s Aquatics Program have announced a record newborn population of the endangered Devils Hole pupfish.

While the number of 17 newborns may seem low, it’s the most ever counted in December and January. Biologists say this is a sample and the actual number of newborns is higher.

The survey to find the young pupfish is done at night, according to biologists, because that’s when the adult pupfish are sleeping and the young are more active.

Earlier pluvial (wet) periods allowed colonization of present sites; subsequent xeric (dry) conditions served to isolate the aquatic habitats, with the result that the inhabiting organisms have differentiated and evolved into the relict species found today. The Devils Hole pupfish have been isolated 10,000 to 20,000 years, longer than any other in the Death Valley system. Devils Hole itself is a water-filled cavern cut into the side of a hill. The cavern is over 500 feet (152 m) deep and the bottom has never been mapped. Devils Hole provides its resident pupfish with conditions of constant temperature (92°F, 33°C) and salinity, unlike the fluctuating environments of many other pupfish. Although pupfish have been found as deep as 66 feet (20 m), the fish forage and spawn exclusively on a shallow rock shelf near the surface, feeding on the algae and diatoms found there. The Devils Hole pupfish is considered an annual species, with the historic population fluctuating between 100 – 200 in winter and 300-500 in late summer. Research indicates that pupfish population numbers respond primarily to the amount of algae present on the shelf. The algal growth depends, in turn, on the amount of solar radiation the shelf receives and the concentration of nutrients in the water. Finally, recent evidence suggests that nutrient availability is highest when the cave is used by barn owls (Tyto alba) as a roosting/nesting site. The owls increase the pool nutrient levels by casting nutrient-rich pellets into the water.

National Park Service

Devils Hole was added to Death Valley National Monument by presidential proclamation in 1952. Ten years later the NPS began monitoring water levels in the hole, and fenced after two divers drowned in its water. In 1967 the Devils Hole pupfish was officially listed as an endangered species.