Endangered Fish Living in Single Death Valley Cave Sees Big Rebound
In a small gulch beneath the balmy waters of Nevada’s Death Valley lives a colony of tiny, colorful fish measuring only about an inch (35mm).
Devils Hole pupfish, which have no natural predators and feed on algae, are the smallest of any vertebrate species on the planet. Scientists long-believed that Devils Hole pupfish had been sequestered from other pupfish populations for 10,000 to 20,000 years.
Recent research has indicated, though, that pupfish only arrived in Death Valley about 10,000 years ago. They have been separated from other pupfish for 1,000 years.
Pupfish were officially added to the Endangered Species List in 1967, one of the first species to be listed. Prior to 1995, the pupfish population numbered about 200 in the spring, and between 300-500 in the fall. The population has always fluctuated, with spring population counts numbering lower due to the scarcity of food in the winter.
In 2013, the population of Devils Hole pupfish cratered to just 35. Yet the last few years have seen a remarkable rebound in their population. This spring, wildlife managers counted 175 Devils Hole pupfish. Last fall, they tallied 263. It marked a 19-year-high in the pupfish population.
“Times are good now with Devils Hole pupfish, compared to how they've been in the past,” Jennifer Gumm, a biologist with the U.S. Fish and Wildlife Service, recently told NPR.
Yet many scientists are still trying to figure out why, and how, the Devils Hole pupfish managed their magnificent resurgence.
Some believe it has to do with a July 2021 flash flood which released a tremendous amount of thick, muddy water. “The volume of water that went into the habitat was just so much,” Gumm recalled. “Walking into it, we just weren't sure what was going to be there. And the water looked like chocolate milk. You couldn't see any fish.”
Each day, however, more and more fish presented themselves to Gumm. It’s likely that the flash flood actually provided the pupfish with fresh nutrients.
Just a few days later, an 8.2 magnitude earthquake rocked Alaska. It was so powerful that it created a mini-tsunami 2,000 miles away in Devils Hole. Video shows the water violently roiling, which likely redistributed nutrients delivered in the flood.
“Earthquake induced spawning is a fascinating aspect of the behavior of this species,” Gumm told the National Park Service last year.
Scientists have even set up an artificial pupfish colony in an underground facility which simulates their natural environment. Currently, the population rests at around 300, most of them harvested from eggs taken from nature. It’s an insurance policy of sorts against the promising, though still-dwindling, pupfish population.
Jennifer Gumm, however, has seen the tenacity of the pupfish and is confident they know how to move forward. “They've been living here for a lot longer than we really comprehend. They are used to it. And they know what to do.”