Life History of the Leon Springs Pupfish, Cyprinodon bovinus

Cyprinodon bovinus experiences a peak in maturity index and mean egg diameter in mid-July; peak frequency of the fish's occurrence in nature occurs in October. Analysis of size-class frequency distribution indicates that C. bovinus individuals live for 20-23 months and participate in only one spawning period. A conspicuous drop in the pupfish populations occurs in winter at stations altered by oil drilling activities. The population decrease is attributed to reduced primary production. C. bovinus exhibits a peak in spawning from 1000 to 1030 hrs, followed by a less conspicuous peak at 1800-1900 hrs. Thermal tolerance in C. bovinus is shown to be somewhat lower than tolerances determined for other desert pupfishes. Morning tolerances are significantly different from afternoon tolerances. C. bovinus is a generalist in food habits, feeding primarily on diatoms, amphipods, and ostracods. Pit-digging is discussed as a behavioral adaptation for feeding. It is recommended that C. bovinus be removed from the United States Department of the Interior's list of extinct United States species and be reclassified as a threatened species.