1992 agency report for the California Department of Fish and Game

KEYWORDS: California; Nevada; Oncorhynchus clarki henshawi; Gila bicolor snyderi; Rhinichthys osculus; Cyprinodon macularius; Cyprinodon; drought; habitat; genetics

ABSTRACT

Wolf Creek, Mono County, was chemically treated for the second year to eradicate non- native species in preparation for the 1993 introduction of Lahontan cutthroat trout (Oncorhynchus clarki henshawi) (CTL). The continuing drought forced biologists to move CTL from the nearly dry By Day Creek, Mono County, and release them into Mill Creek, which was also recently chemically treated.

With money provided from drought relief funds, additional habitat was developed for the Owens tui chub (Gila bicolor snyderi) at the Hot Creek headsprings. These springs are critically low due to drought, upslope water development and geothermal development in the area. The habitat development will result in nearly a doubling of existing habitat at the site.

Preliminary results of our University of Nevada, Reno contract investigating the taxonomic relationships of speckled dace (Rhinichthys osculus) populations indicate that fish from the Owens River drainage are more closely related to fish from the Lahontan drainage than the Colorado River drainage. The Amargosa River population is the most genetically distinct.

The Department, based on the numerous Cyprinodon macularius found during a 1991 pupfish survey around the Salton Sea, effected a regulation change that eliminates or modifies bait fishing gear that could result in "take" of pupfish. The Department also provided some funding and collected fish for an Arizona State University electrophoretic study of Cyprinodon macularius.

Additional ponds were developed at Shoshone Springs for Shoshone pupfish (Cyprinodon nevadensis shoshone). The habitat for this fish consists only of two artificial ponds which could be lost in a severe thunderstorm or other event.

Molecular genetic studies of California (and some Nevada) pupfish populations will begin in November 1992. The study's primary focus is to examine the genetic relationships within Cyprinodon nevadensis complex and determine (at the subspecies level) from those in the Amargosa River. The study will also include samples from the following populations: Cyprinodon diabolis, Cyprinodon radiosus, Cyprinodon salinus ssp. and Cyprinodon macularius.

RESUMEN

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