"The back-to-back earthquakes occurred during winter when no direct sunlight reaches the pool, preventing algae regrowth."
Crisis in the Deep: The Devils Hole Pupfish
In early 2025, the world's rarest fish faced an existential crisis. The population of Devils Hole pupfish (Cyprinodon diabolis) in Death Valley National Park plummeted from 212 fish in fall 2024 to just 20 individuals by late February 2025.
Cause of the Collapse
The dramatic decline was triggered by two seismic events in December 2024 and February 2025. The earthquakes caused significant water sloshing inside the unique geothermal pool, which removed the essential algae that serves as the pupfish's primary food source.
The timing was catastrophic. Because the earthquakes struck during winter, no direct sunlight reaches the pool's surface, preventing the algae from regrowing naturally.
An Emergency Intervention
Facing an unprecedented crisis, an interagency Incident Command Team—comprising the U.S. Fish and Wildlife Service, National Park Service, and Nevada Department of Wildlife—made a historic decision.
For the first time ever, they decided to release captive-bred pupfish from the Ash Meadows Fish Conservation Facility into Devils Hole.
- March 11, 2025: 19 captive-bred fish were released.
- Shortly after: Approximately 50 more fish followed.
The releases were expedited due to extreme urgency from the critically low wild population and growing uncertainty over a potential government shutdown and federal layoffs that could halt operations entirely.
The DNA Dilemma
In a controversial but necessary compromise, biologists did not take DNA samples (fin clips) from the released captive fish before release. The team justified this decision by explaining that fin clipping would require a week of antibiotics and recovery time—time they simply did not have.
Instead, they attempted an untested technique: saving water samples from the pool for DNA extraction to monitor genetic diversity.
Signs of Recovery
As of spring 2025, a count found 77 fish in Devils Hole—a significant increase from the February low. More importantly, biologists observed many young fish, confirming that reproduction had resumed in the wild.
Transfers of captive fish continued, with a February 2026 release noted as uneventful—a welcome sign that the emergency measures were stabilizing the population.
"Biologists did not take DNA samples... stating that fin clipping would require a week of antibiotics and recovery time, which was not possible given the perceived urgency."