Control of Exotic Species in a Desert Pupfish Pond

Authors: Ginny Short

Year: 2010 (xlii)

Abstract

In the early 1990s, the California Department of Fish and Game (DFG), translocated a population of desert pupfish (Cyprinodon macularius) from the Salt Creek near the Salton Sea to the McCallum and Thousand Palms Oases in the Coachella Valley, California. This established a Á¯Â¿Â½Tier 1 RefugiaÁ¯Â¿Â½ for the Salt Creek population of the desert pupfish according to the recovery plan for the species. This Refugia is owned and managed by the Center for Natural Lands Management. Concerned by a precipitous decline in pupfish numbers in 2004-2005, it was decided to attempt to eradicate or reduce exotic species from the pond. Prior to the clean-up effort, the pond was monitored for pupfish; only two males were found. In 2009 we attempted to dry out the pond and initiate vegetation management. In 2010, we applied an experimental molluscide (Bayluscide) to target the snails and crayfish. Pond dessication had mixed results. While there was some mortality in fish and crayfish, and certainly thousands of snails died as a result, there were literally thousands of snails, fish and crayfish still present at the conclusion of this effort. The application of Bayluscide had an effect on the snails. Many snails were killed and virtually all the fish in the pond were killed. However, there was no visible effect on the crayfish. We continue to trap and remove the crayfish, monitoring for the presence of the other target species and are planning the next step, including toxicity tests on the crayfish to determine the correct concentration of Bayluscide. We continue vegetation management and are looking at other potential ways of control and or eradication of these species.