Cyprinodon nevadensis calidae

  • Common name: Tecopa Pupfish
  • Classification: Actinopterygii → Cyprinodontiformes → Cyprinodontidae
  • Extinction date: Declared extinct in 1981 (last confirmed sighting in the early 1970s)
 

       Scientific and Historical Significance

  • The first officially recognized extinction of a North American fish species under the U.S. Endangered Species Act.
  • Considered a cautionary example of how localized habitat modification can eliminate an entire species.
  • Its extinction contributed to modern conservation policies regarding small-range endemic species.

Hot spring modification reduced natural habitat.
Hybridization with related pupfish reduced genetic integrity.
Introduction of non-native fish created competition
Recreational development disturbed water flow.
Small population size increased extinction risk.

The blue pupfish once swam in Death Valley’s Tecopa hot springs, adapted to heat but lost to human alteration. Around them, extinct kin form a constellation of absence. Bones and sand mark survival erased, memory alone remaining.


Hot springs outflows in Tecopa, Inyo County, California, USA


Endemic to the hot springs of Tecopa, California, the pupfish Cyprinodon nevadensis calidae lived in a unique desert oasis. Its survival depended on the steady flow of warm mineral water and the algae that grew along the shallow pools.
In the mid-20th century, the springs were modified for bathing and recreation, altering water temperature and flow. At the same time, non-native fish were introduced, bringing new competition and hybridization with closely related pupfish. The tiny population, already limited to a single site, began to collapse.
By the 1970s, surveys found only scattered individuals. In 1981, the Tecopa pupfish was officially declared extinct—the first species removed from the U.S. Endangered Species List due to extinction, a reminder of how even small environmental changes can erase a species.

      























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