An "Extinct" Fish Finds Life Again in a Parched Desert: The Saga of the Shoshone Pupfish

The pupfish habitat at the springs in Shoshone, east of Death Valley National Park

Of all the things one might look for while exploring intense desert environments, what is the most unlikely form of life you would expect to encounter? Fish of course. It's practically an oxymoron to use the term "desert fish". But in the harsh desert environments of eastern California and western Nevada, there are indeed fish. And not just a single species, but around a dozen species and subspecies. There are nine distinct populations of the Cyprinodon Pupfish, three species of Speckled Dace, and a Poolfish. How they survive today, and how they got there in the first place is a fascinating story.

How they survive is not difficult to understand: despite the aridity of the California desert, there are sources of water. There are permanent springs and pools of water scattered all around Death Valley and the Amargosa River Basin, and the fish have adapted to life in waters that might be hot, cold, fresh, or salty.

How they got there in the first place is a little trickier to understand. Our climate has been subject to huge variations over the last two million years, and more than a dozen times, it got much cooler and glaciers developed and expanded, especially in the Sierra Nevada mountains. Some of the meltwater from those glaciers flowed into the deserts of the Basin and Range province and accumulated in huge freshwater lakes. As a lake basin filled (such as at Mono or Owens Lake), it spilled over into the next lake basin until a network of lakes extended from the Sierra Nevada to Death Valley. The Amargosa River flowed through western Nevada, also ending in Death Valley. So there was plenty of water once upon a time.

At some point in time, a connection was made with the Colorado River, and fish were able to make their way into the network of freshwater lakes, and they thrived. But as each glacial stage ended, the lakes would begin drying up and most of the fish lost their habitat and went extinct. But those very few species that could adapt quickly enough took refuge in the rare and isolated springs and pools. A few, including the Lahontan Cutthroat Trout survived in the cold streams, lakes and rivers of the eastern Sierra Nevada. Those trapped in saline waters had to adapt to the salty conditions. Some fish adapted to high temperatures,  and unlike pretty much any other fish in the world can survive in water that reaches a hundred degrees or more.

One of my very few photos of the Devils Hole Pupfish, taken from around 100 feet away.

Perhaps the most famous of these fish is the Devils Hole Pupfish (above), found in a single cavern opening in the Ash Meadows National Wildlife Refuge (the spring officially lies in an outlier of Death Valley National Park). Their story is compelling, but they are not the fish I'm discussing today. You can read about them if you wish here or here.

 

The various populations of pupfish survived for thousands of years in isolation from human developments. But the colonization and occupation of the desert by miners and ranchers spelled doom for some of them. One species, the Tecopa Pupfish, was driven extinct pretty much in an afternoon when pipes were installed at the one spring where they lived. A similar fate apparently happened to a different subspecies, the Shoshone Pupfish (Cyprinodon nevadensis shoshone) in the 1960s as springs in that area were developed for domestic use at the village of Shoshone. The species was declared extinct in 1969, as none could be found anywhere.

Improbably, a small population of the fish actually survived the devastation of their original habitat by taking refuge in a nearby irrigation ditch, unnoticed by anyone. In 1986 they were rediscovered, and a cooperative effort by the private landowner and several environmental organizations resulted in a resurrected habitat. This habitat was actually expanded to three pools and some artificial off-site refuges as well. Despite visiting Shoshone yearly for the last three decades, I never heard about the efforts being made on behalf of the fish's well-being. 

That changed last week when I found out that a nature trail had been constructed, and interpretive signs posted that allowed for some close viewing of the diminutive fish (as well as another highly endangered creature, the Amargosa Vole). The site also serves as an excellent habitat for a large variety of birds, and we saw Western Bluebirds, Yellow-rumped Warblers, White-crowned Sparrows, a Costa's Hummingbird (a life-lister for me) and we could hear Verdins chattering away in the brush.

The trail is just off the main highway in Shoshone, and the locals seem proud of the efforts and can easily point the way to the trailhead, next to the local school. If you ever travel to Death Valley from the east, you can't miss the town. It's the only gas station and food stop for many miles. Don't forget to stop in at the local museum for a look at the Columbia Mammoth fossils on display inside!

 

How Did Fish Get into the Desert of the Basin and Range Province?

Source: "Pleistocene Lakes and Rivers of Mojave" by Philip Stoffer (14 January 2004). Changing Climates and Ancient Lakes (.html). Desert Landforms and Surface Processes in the Mojave National Preserve and Vicinity. USGS, US Department of the Interior. Retrieved on 2009-09-12. - http://pubs.usgs.gov/of/2004/1007/images/glaciallakes.gif.

Following a pair of posts that mention fish in the desert (here and here), I received a comment asking where the connections were that allowed fish to make the journey from the Colorado River system into areas as isolated at the Owens Valley and Death Valley. Courtesy of Philip Stoffer of the U.S. Geological Survey, here is the map. The drainage through Danby, Cadiz, and Bristol Lakes is the probably route of numerous fish species during the ice ages. From there, they were able to move through Soda and Silver Lakes into the Death Valley-Owens River system.

It is an unexpectedly diverse group of fish. According to this report, there were 56 species and 75 subspecies of fish living in the Basin and Range/Mojave Desert provinces. Ten of these historically known species/subspecies are extinct. Another 75 are listed, are candidates for federal listing, or are species of concern. 9 out of 10 of the subspecies are endemic, meaning they are found nowhere else in the world. The fish include the highly endangered Devils Hole Pupfish, the popular Lahontan cutthroat trout, as well as a variety of dace, chubs and suckers.

The story of why they are endangered is easy to summarize. They need water to survive, and so do humans. It is the choices that humans make that will determine the future of this fascinating group of fish. The Owens pupfish (Cyprinodon radiosus) would be extinct today but for the intervention of a Fish and Wildlife officer who carried the worlds entire population (800 individuals) out of a drying pond in two buckets, and established the fish in six other localities (four of these remain). The Devils Hole Pupfish in Death Valley National Park exist today because of a Supreme Court decision halting the drilling of groundwater near the only pool in which they exist.

A Death Valley Pupfish, found in Salt Creek on the floor of Death Valley.

 

 

Joshua Trees Blooming Across the Southwest: Is it a problem or just a good year?

During my travels a few weeks back, I noticed a lot of Joshua trees were blooming along Highway 138. We stopped and snapped a few close-ups without giving it much thought. I knew they bloom off and on in different parts of the Mojave Desert. It has come to my attention, via the Press-Enterprise of Riverside, that the Joshua trees are actually blooming everywhere in the Mojave this year. It's unusual, with millions of the trees producing flowers.

According to the article, biologists are not in agreement about what this means. Some seem to think that the bloom is evidence of plentiful soil-water conditions because of extensive late summer-early fall rainstorms.  Others point to two years of overall severe drought, and average temperatures that are 2-3 degrees above average. The trees are reproducing because of stress, a sort of last gasp to produce seed before dying.

Being a geologist, I can't speak to the precise reason for the once-in-a-lifetime bloom, but geologists have provided some perspective about the prospect for the species' survival. Global warming is in fact leading to higher temperatures across the southwest, and the trees must propagate at higher elevations to survive as a species. This has become difficult over the last few thousand years, because there are no longer any grazing animals that can consume the fruits and spread the seed via their droppings.

The last far-ranging animal that did so was the Shasta ground sloth (Nothrotheriops shastensi) , which went extinct across the southwest more than 12,000 years ago. Without the animals to spread the seeds, they can only fall to the ground underneath the parent tree. There are some fears that the Joshua tree will disappear from its namesake National Park in a few generations.

And that would be a real shame. They are beautiful trees.