A sign shows images of the endangered Devils Hole Pupfish in Nye County, Nev. Tuesday, March 5, 2024. Devils Hole is located in a detached unit of Death Valley National Park and surrounded by the Ash Meadows National Wildlife Refuge.
Wednesday, May 1, 2024 | 2 a.m.
A population spurt for the Devils Hole pupfish, a critically endangered fish at Death Valley National Park, is giving scientists cause for optimism, the National Park Service said.
Scientists from the park service, the Nevada Department of Wildlife and the U.S. Fish and Wildlife Service counted 191 pupfish at Devils Hole over the course of their spring study April 5 and 6, officials said. That marks a 25-year high, they said.
“Increasing numbers allow the managing agencies to consider research that may not have been possible in the past, when even slight perturbations of habitat or fish had to be completely avoided,” said Michael Schwemm, senior fish biologist for the U.S. Fish and Wildlife Service. “We’re excited about the future directions with respect to managing this species.”
Many pairs of the fish were found courting and spawning in their 92-degree habitat, officials said.
The species fully resides in Devils Hole, a water-filled cavern near Ash Meadows National Wildlife Refuge in Nye County. Officials say Devils Hole is the smallest habitat of any vertebrate species on the planet.
The fish are found in the upper 80 feet of the cave and depend on an 11-by-16-foot sunlit shallow shelf at the cavern’s entrance for food and spawning, officials said.
Historically, the pupfish’s population ranges between 100 to 200 in winter and 300 to 500 in late summer — an all-time low of 35 fish was recorded in 2013.
The tiny fish, averaging less than 1 inch in length, lived in relative isolation for between 10,000 and 20,000 years after periods of flooding and dryness created the cavern they call home, the park service said.
Flooding last summer from Hurricane Hilary was a benefit to the fish’s ecosystem, officials said, because it added nutrients that washed off the surrounding land surface in a fine layer of clay and silt.
Using scuba gear, scientists dove 100 feet below into the habitat to count the fish population. A second team counted near the shallow shelf where the fish were visible.
“It was really encouraging to see such a large number of young fish during these spring dives,” said Brandon Senger, supervising fisheries biologist for the Nevada Department of Wildlife. “Conditions within Devils Hole looked healthy, so we have hopes of high recruitment over the coming months that will lead to a large population in the fall.”
The species was declared endangered in 1967. The following year, commercial drilling and pumping near present-day Ash Meadows National Wildlife Refuge began to sap away the springs that feed Devils Hole and keep the pupfish habitat intact.
Patrick Donnelly, Great Basin director for environmental nonprofit Center for Biological Diversity, said exploratory drilling and a proposed lithium mine near Ash Meadows could pose a new threat to the recovering endangered species.
“The amount of water in there is reflective of the health of Ash Meadows,” he said. “I think there’s this tendency to think of Devils Hole as this oddity that’s separated from the rest of the ecosystem, but actually the health of Devils Hole is the health of all of Ash Meadows and Death Valley.”
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