Fishes Ninety-one native fishes occur in a variety of aquatic habitats. Of that total, 53 are endemic species and subspecies. The number of fishes unique to Nevada is large because thousands of year ago, large postglacial lakes and streams receded. Remnant water bodies became more isolated as the climate became increasingly arid. Over time, separated populations of fish species adapted to changes in stream flow quantity and patterns as well as changing water quality conditions. During centuries of isolation and adaptive change, surviving fish species became genetically unique. Some very rare fishes live in a single spring or stream. One of many examples is the Devils Hole pupfish, which lives in one deep-water pool at Ash Meadows National Wildlife Refuge. The pupfish was nearly extirpated in the 1970's when the level of the pool was drawn down by pumping from groundwater wells near Ash Meadows. Native fishes living in small water bodies are all the more vulnerable to the combined threats of drought and human activities that change the amount of water in the system, modify the habitat, or introduce more competitive foreign species. The Devils Hole pupfish is one of thirty-two fish species classified as protected, threatened, or endangered by state law. In addition, 11 fishes are designated sensitive by state law (Nevada Administrative Code 503.065). Sixty-three taxa are considered rare or sensitive by the NNHP. Lahontan cutthroat trout, a native of desert and mountain streams and lakes, occupies only about 10 percent of its historic habitat.  In many places, stream and lake ecosystems are impaired by changes in water quantity and quality, channel structure and stability, riparian plant cover, and nonnative fishes.  Other sensitive native trout species, such as Bonneville cutthroat trout, inland Columbia Basin redband trout, and bull trout, exist in similar limiting conditions.  Cooperative restoration projects on Marys River, Eightmile Creek, Maggie Creek, East Fork Quinn River, and others show streams can be mended to benefit fishes, songbirds, waterfowl, wading birds, upland birds, and mammals.   Conditions for outdoor recreation and grazing also improve. Photo by Pete Rissler. More than 200 reservoirs and lakes and 500 streams are distributed throughout the mountains and valleys. A variety of cold and warm water fisheries are maintained for angling. Many species of non-native game fish have been introduced into these waters. Notable game fish are rainbow, brook, and brown trout, largemouth bass, several species of catfish, perch, walleye, and striped bass. Another introduced species, the carp, was originally hailed as a fabulous food and game fish. Now ubiquitous, carp have proved to be a scourge and virtually impossible to eradicate. Most sport anglers concentrate on non-native species, populations of which are either self-sustaining or supplemented by hatchery stock. The Lahontan cutthroat trout (LCT) is the state fish. Native to the Great Basin, the LCT was once widely distributed throughout northern Nevada. A close relative is the Bonneville cutthroat, which populates mountain streams and lakes within the Lake Bonneville Basin in easternmost Nevada. The LCT has a lacustrine (lake dwelling) and a fluvial (stream dwelling) form. The lacustrine strain lives in Pyramid, Walker, and Summit lakes. The fluvial (stream dwelling) fish occurs in the Humboldt River system, isolated streams in northwestern and central Nevada, and tributaries of the Truckee, Carson and Walker River tributaries. The FWS designated LCT as a threatened species because populations throughout much of its native range have been eliminated. Reasons for this decline include alteration of stream channel and riparian habitats; water diversions that reduce stream flow and lake levels; impaired water quality in lower river reaches and terminal lakes (e.g., Walker and Pyramid lakes); dams and other obstructions to migration; and, the introduction of non-native game fishes and other competitive animals. Substantial efforts to improve the fisheries and increase the number of water bodies maintaining reproducing LCT populations have been undertaken by the FWS, NDOW, Pyramid Lake and Summit Lake Paiute Tribes, and others. Gains have not been sufficient to remove LCT from the Endangered Species List. An implementation plan for the improvement of the Truckee River system is being developed to assist in the recovery of the LCT and endangered cui-ui. Maintenance of recreational fishing opportunities is a goal of the planning process. A planning process has also been initiated by the FWS for LCT in the Walker and Humboldt River systems and in northwestern Nevada (U.S. Fish and Wildlife Service, 2001). To sustain popular lake and reservoir fisheries, resource agencies in Nevada operate seven fish hatcheries and rearing stations. Three are run by NDOW (Mason Valley, Lake Mead, and Gallagher near Elko), three by the Pyramid Lake Paiute Tribe (Dave Koch and David Dunn at Sutcliffe, and Numana near Wadsworth), and one by the FWS (Lahontan, near Gardnerville). Native fishes on the Endangered Species List and introduced species are produced at the hatcheries. The April 2001 NDOW fish stocking update reported over 51,500 rainbow and brown trout, and almost 82,800 hatchery-reared Lahontan cutthroat trout were planted in Nevada waters. Almost all the cutthroat trout were placed in Walker Lake, with a small fraction going into Topaz Lake. About 99 percent of the other trout species were planted in 15 lakes and reservoirs located in both rural and urban areas. The Carson and Truckee rivers received the remaining one percent. In a May 2001 update, NDOW reported planting another 200,000 rainbow, brown, and rainbow-cutthroat hybrid trout were planted in many rivers, creeks, and reservoirs. The NDOW data do not include fish plantings by the Pyramid Lake Paiute Tribe nor the FWS. Other groups of native fish species include various minnows, (e.g., dace, chubs, shiners) (Cyprinidae Family), suckers (Catostomidae Family), pupfishes (Cyprinodontidae Family), and several springfishes and poolfishes (Goodeidae Family). Like many other fishes, these have evolved into numerous distinct forms in isolated water bodies. For example, the nearest relative of poolfishes in Nevada occurs in central Mexico, and nowhere else in the U.S. An important lakesucker species is the cui-ui, unique to Pyramid Lake and important to the Pyramid Lake Paiute Indian Tribe. The cui-ui population declined early in the 1900's when dams, diversion, channel erosion, and delta formation blocked access to essential fresh water spawning habitat in the lower Truckee River. Cui-ui are hatched and reared at the Dave Koch hatchery as part of the effort to recover this endangered species. Invertebrates An overlooked group of organisms is our invertebrate population. Although there is much to still be learned, worldwide diversity among this group is probably higher than all other wildlife combined. Invertebrates occupy virtually all habitat types even lightless caves, alpine tundra, and searing sand dunes. Invertebrates play a critical role in pollination and are an essential food source of insectivorous predators higher on the food chain. Butterflies are a relatively well-known group of invertebrates. Nevada ranks ninth among all states in the diversity of resident or regularly occurring colonies of butterflies. Butterflies are found in almost every habitat type. Some butterflies, The Apache silverspot butterfly is being studied in the Toiyabe mountain range of central Nevada.  Biologists are learning about factors affecting the absence or presence of breeding populations of animal species requiring specific habitat types.  Field research shows the Apache silverspot is very particular about plants used during life cycle stages.  Suitable breeding habitat patches contain a singular violet species and select thistle species that co-occur in riparian areas.  The study found that the presence of breeding populations was more related to plant composition and vegetation structure than the size or proximity of suitable habitat.   Such research provides valuable information to land use managers responsible for sustaining sensitive species, among other conservation goals.  Photo courtesy of Erica Fleischman, Stanford University, Center for Conservation Biology such as the painted lady (Vanessa cardui), are migratory, while others are specialized residents of narrow habitat types. Incredibly, the Sand Mountain blue (Euphilotes pallescens arenamontana) inhabits only one sand dune in Churchill County. In addition to the showy characteristics and bright colors that provide us with an immeasurable aesthetic resource, butterflies also perform the critical ecological function of pollinating many types of plants. There are approximately 200 species and 170 additional subspecies of butterflies known to exist in Nevada. Thirty-one taxa are endemic. In most cases, butterflies rely on only one or a few closely related plant species to feed and lay their eggs. In central Nevada mountain riparian zones, the Apache silverspot butterfly (Speyeria nokomis apacheana) requires a single violet species during its larval stage, and four thistle species for nourishment as an adult. The high degree of habitat specificity makes such butterfly species all the more vulnerable. Springsnails are an interesting group of invertebrates. These freshwater, gill-breathing mollusks occur throughout North America, primarily in springs. In Nevada, many species specialize in extreme habitats including springs with temperatures ranging from 37º F (3º C) to 111º F (44º C). More species of Pyrgulopsis, the largest genus of springsnails, occur in the Great Basin than anywhere else in the U.S. Most springsnail populations are highly isolated because springs and seeps are widely dispersed and disconnected. Indeed, many species' entire range is in just one small spring. A number of springsnail populations are declining, almost faster than we can learn about them. Their aquatic habitats are rare and sensitive to drought and to the manner in which water resources are used. Much remains to be learned about the diversity of Nevada's invertebrate populations, their distribution, conservation status, and special ecological functions. Currently, no invertebrates are afforded state protection. As scientists continue to monitor and survey populations, undoubtedly new species will be described and more will be learned about Nevada's exceptional diversity. Next Page -- Endangered, Threatened, and Sensitive Fauna and Flora Back to Table of Contents