Devil's Hole Pupfish

One species that particularly fascinates me is the Devil’s Hole pupfish (Cyprinodon diabolis), which has the most restricted distribution of any vertebrate species. This pupfish is restricted to a single sinkhole in the vicinity of Ash Meadows National Wildlife Refuge. The sinkhole is about 15 meters deep, and an equal distance wide at the desert’s surface; at the bottom is a pool that is, at most, 20 meters long and 3 meters wide. The waters extend down to at least 450 feet, and are a constant 93°F – although the pupfish spend most of their time near the surface, especially on a 10-meter-long shelf no more than 30 centimeters deep. This shelf is crucial to the species’ survival, because that is where productivity (i.e., food) is highest, and where most of the fish spawn. Water depth thus becomes a crucial issue – and in the past, groundwater mining in the Ash Meadows area (before it became a refuge) lowered the water level about 60 centimeters. The threat to the pupfish eventually led to federal ruling to stop water pumping, which in turn led to a lawsuit.  Eventually, in 1976, the U.S. Supreme Court ruled unanimously that the federal government has the right to restrict water withdrawals if they affect the water table beneath its land. Conservationists and biologists rejoiced, but some Nevadans were not so pleased; an editorial in one newspaper suggested that the solution to the Devil’s Hole pupfish “problem” was rotenone, a fish poison.

Devil's Hole Pupfish

The pupfish are managed jointly by the U.S. National Park Service, U. S. Fish and Wildlife Service, and the Nevada Division of Wildlife. I spent the 24^th and 25^th of September observing the semiannual Devil’s Hole pupfish count, which involved two divers (plus their safety backups) and three biologists doing surface counts. When the biologists were not working, I could lay on a temporary grating and observe the pupfish from a distance of only a few inches. They are remarkable creatures. As in many other pupfish, spawning males are an iridescent blue. However, they are much less aggressive than most other pupfish, and show little evidence of territoriality. They also are smaller than other species – their maximum length is less than two inches - and they are able to persist in a high-temperature, low oxygen, and low productivity environment. To think that they have done so in this one pool, for at least ten thousand years – the estimated time since they were isolated from other pupfish – is amazing. 

Divers Preparing to Count Pupfish

When the divers were eating lunch and resting between dives, I lay on the grating and watched the pupfish go about their business – patrolling their space, tugging at bits of food, engaging in the occasional chase.  There are less than two hundred adults now, and there is nowhere else for them to go. There are other springs and other pupfish close by – as they crow flies, less than two miles away – but as the pupfish swims, their relatives might as well be an ocean away. I thought about these fish, living out their lonely lives, isolated for the last ten thousand years or more.  What are their lives worth? Are they worth the $400,000 per year that the Park Service allocates for research and protective measures? The answer lies beyond traditional cost-benefit analyses, of course. I am hoping that some sort of eloquent answer to this question will come from my time in the desert, but for now I’ll gladly say that my heart and mind stand with the pupfish. Lying on that grate, and looking down at the pupfish – or up at the clear blue vault of the desert sky – the tenacity of those tiny creatures, their patience in the face of ten thousand years of isolation, is astounding.