Food Bottlenecks to Larval Recruitment of Devils Hole Pupfish

The Devils Hole Pupfish, Cyprinidon diabolis, is found in a single limestone fissure in Death Valley National Park, the Devils Hole Pupfish has survived in its current location—perhaps the smallest vertebrate distribution in the world—for the last 25,000 years. Recent, dramatic declines in the Devils Hole Pupfish population have raised concerns over the future of the species. As there are no remaining refugia for pure-strain pupfish outside of Devils Hole, the possibility of extinction has become quite real. Previous lack of success for rearing fish in laboratory settings coupled with low egg viability further complicate recovery efforts. Census divers and scientists associated with the Devils Hole program have reported sighting larval pupfish on the stone shelf, as well as adult fish throughout the upper reaches of the water column. However, there are few reports of middle-age class fish, and with numbers of adults that are significantly lower than previous years, it seems that many larval fish are simply not surviving to the adult age class. In hope of aiding recovery efforts, we have begun cultures of algae and zooplankton species native to Devils Hole. In order to determine whether a shift in the algal and invertebrate communities has adversely affected the ability of larval pupfish to survive to later age classes, native Devils Hole algal species and invertebrates have been isolated and fed to larval pupfish immediately post-hatch through two weeks of age. Length is then measured to determine differences in growth.