07 April 2019

Salt Creek Desert Pupfish

Last week I spent a few days camping in the desert regions east of the Sierra Nevada, down to Death Valley. One of the highlights was viewing the endangered Salt Creek Desert Pupfish (Cyprinodon macularius). There are only a few populations left - remnants from the Pleistocene era Lake Manly.
Lake Manly was a giant lake covering what is today Death Valley, to depths of 600 feet. A few thousand years later, it is gone, and all that remains are salt flats an ephemeral streams. Somehow these fish managed to adapt to the extreme temperatures, high salinity (3x that of the ocean) and seasonal nature of the waters.
The pupfish are only a couple inches long, and defend small territories (a square meter or two) in the shallow creek. In fact, one of my pictures is a territorial squabble by two males. They only have a few months to mate and lay eggs before they perish. And the cycle starts again next spring when the eggs hatch and new generation repeats the task.
The only thing keeping this group of pupfish from being Critically Endangered is that there are two disconnected populations. Note that until recently, all desert pupfish were thought to be a single species with different sub-species that had slightly different life strategies. Recent DNA evidence has resulted in them being split into three distinct species.
That said, it was discouraging to see people walking in and along the creek, despite signage saying not to. Thankfully it is only early April - in another few weeks each step they were taking would likely crush dozens of pupfish eggs.
Male Pupfish

Male Pupfish

Male and Female Pupfish

Two Males Fighting Over Territory