Great Basin and Mojave Desert Fishes and Aquatic Ecology
The highest incidence of federally listed threatened and endangered fish species occurs in the Great Basin and Mojave deserts. Many are endemic forms living in isolated springs and fragmented habitats. A primary cause of decline has been anthropogenic habitat alteration. For example, the proliferation of the human population in the driest region in North America, the Mojave Desert, has taxed water resources there; now there are designs for a trans-basin pipe line to convey water from second driest region in North America, the Great Basin, to the largest city in the Mojave Desert, Las Vegas. This plan, along with pumping water from the carbonated aquifer in the Mojave Desert, could negatively impact 12 federally listed fishes, 6 fishes of special concern, and numerous endemic invertebrates, several of which are also federally listed. Not only is water flow and volume an issue: changing water temperature associated with reduced flow is a potential problem, since many of these endemic species are thermophilic and restricted to narrow temperature ranges. To assist managers in their efforts to protect and preserve listed desert species in a changing environment, Reno Field Station (RFS) biologists study their status, ecological requirements, and population dynamics.
Invasive species is the other primary threat to fishes and aquatic invertebrates of the Mojave and Great Basin deserts. Particularly troublesome nonnatives include blue tilapia (Oreochromis aurea), convict cichlids (Amatitlania nigrofasciata), green sunfish (Lepomis cyanellus), largemouth bass (Micropterus salmoides), sailfin molly (Poecilia latipinna), shortfin molly (Poecilia mexicana), mosquitofish (Gambusia affinis), brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and crayfish. All of these species have caused native fish decline in the respective desert aquatic system each has invaded. Biologists from the RFS study interspecific effects between native and nonnative species along with life history and habitat use of invasive species so that strategies can be developed to control are extirpate them. Since nonnative fishes are most successful in anthropogenic altered habits, a means of control is habitat restoration based on habitat conditions that favor native species over nonnatives. Another method of control is disruption of nonnative fish life history patterns such that they are eliminated. Many of the federally listed species are on federal lands, making habitat manipulation feasible.
Information generated by the RFS is used in recovery plan preparation and revision, biological opinions, section seven consultations, recovery teams and technical working group involvement. Information is also used for hands on species management and habitat restoration.
Examples of studies under this project are as follows:
- Technical assistance
- Cui-ui population viability analysis
- Lahontan cutthroat trout and nonnative trout interactions
- Relative abundance, distribution, life history, and population dynamics of fishes and crayfish in Ash Meadow, Nye County, Nevada
- Independence Valley speckled dace relative abundance and distribution
- Habitat favoring native Ash Meadows fishes over the nonnative red swamp crayfish