New Hope for the Leon Springs pupfish

Endangered Species Bulletin, Dec, 2007 by Nathan Allan, Jennifer Gumm

Behavioral observations in May 2006 revealed a drastically reduced breeding population with very few territorial or satellite males. The Fish and Wildlife Service and TPWD rushed to approve a recovery grant to recreate the necessary spawning shelves. The open water needed for spawning was in short supply due to an increased density of emergent vegetation. In early 2007, with help from TNC, Lehigh University students removed the vegetation by hand and replaced it with hard tiles. By spring, the fish responded positively; males reestablished their territories on the new habitat, and biologists saw increased numbers of juvenile fish.

Overshadowing the local threats from hybridization, pollution, and subtle habitat changes is the pervasive threat to groundwater availability. The potential for loss of spring flows due to regional groundwater pumping is a constant danger. Diamond Y Draw is a small sanctuary within the Chihuahuan Desert. As an oasis in this dry region, it supports much more than just the pupfish. It is home to more than eight rare species, including the threatened Pecos sunflower (Helianthus paradoxus), the endangered Pecos gambusia (Gambusia nobilis), the endangered Pecos assiminea snail (Assiminea pecos), two other spring snails that are listing candidates, and several other endemic aquatic invertebrates. Many partners have worked hard over the past 40 years to ensure the Leon Springs pupfish survives, but still more work lies ahead to conserve its fragile ecosystem at Diamond Y Draw.

Nathan Allan (nathan_allan@fws.gov; 512/490-0057 x237) is a fishery biologist in the Service's Austin, Texas, Ecological Services Field Office. Jennifer Gumm (jmg404@Lehigh.edu), a student at Lehigh University, recently completed a work assignment at the Dexter NFHTC.