Unusual Dominance by Desert Pupfish in a Shallow Experimental Pond System Within the Salton Sea Basin

Authors: Michael K. Saiki, Barbara M. Martin, Thomas W. Anderson

Year: 2010 (xlii)

Abstract

In October 2006, several months after a shallow experimental pond system in the Salton Sea Basin was filled with pumped water from the Alamo River and the Salton Sea, evidence of fish life was observed in several ponds even though inlet pipes were screened in an attempt to exclude fish. In June 2007, the fish were identified as desert pupfish, Cyprinodon macularius. From October 2007 to November 2009, nine field surveys were conducted at roughly seasonal intervals with baited minnow traps to document fish species composition and relative abundance. The surveys yielded 3,620 fish represented by five species. Desert pupfish, the only native species encountered, was also the most numerous and comprised over 93% of the cumulative catch. Nonnative species included western mosquitofish, Gambusia affinis, 4.1%; sailfin molly, Poecilia latipinna, 2.8%; and tilapia, a mix of hybrid Mozambique tilapia, Oreochromis mossambicus x O. urolepis, and redbelly tilapia, Tilapia zilli, <0.1%. The dominance by pupfish, which persisted over the two years covered by our study, was unusual because fish surveys conducted in nearby agricultural drains yielded relatively few pupfish.