Cui-ui
| Cui-ui | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cypriniformes |
| Family: | Catostomidae |
| Genus: | Chasmistes |
| Species: | C. cujus |
| Binomial name | |
|
Chasmistes cujus Cope, 1883 |
|
The cui-ui (Chasmistes cujus) is a large sucker fish endemic to Pyramid Lake and, prior to its desiccation in the 20th century, Winnemucca Lake in northwestern Nevada. It feeds primarily on zooplankton and possibly on nanoplankton (such as algae and diatoms). The maximum size of male cui-ui is approximately 53 cm (21 in) and 1.6 kg (3.5 lb), while females reach approximately 64 cm (25 in) and 2.7 kg (6.0 lb). The life span of cui-ui is typically about forty years, but the fish do not reach sexual maturity until at least age eight. The cui-ui is an endangered species, and one of the few surviving members of its genus.
The cui-ui population is generally improving in numbers, having attained an estimated population exceeding one million in 1993, thanks to the efforts of the U.S. Environmental Protection Agency in analysis of the Truckee River spawning grounds and of the Nevada Department of Environmental Protection and EPA in following up on protection measures. The reason the cui-ui remains endangered (though upgraded from critically endangered in 2014) is the recent history of recruitment variation, illustrating that in many years of the 1970s and 1980s there was virtually no recruitment whatsoever due to unsuccessful spawning in an unfavorable water quality and water flow environment of the Truckee River. The species' outlook is somewhat sanguine, since there is a published recovery plan based on an enhanced understanding of Pyramid Lake and Truckee River water quality, and the adoption of a protection plan by the U.S. Congress.
Pyramid Lake, the second largest natural lake in the western U.S. prior to construction of the Derby Dam, has been the focus of several water quality investigations, the most detailed starting in the mid-1980s. Under direction of the U.S. Environmental Protection Agency, a comprehensive dynamic hydrology transport model was developed by Earth Metrics Inc.; the model's name was subsequently changed to DSSAM, and it was applied to analyze impacts of a variety of land use and wastewater management decisions throughout the 3,120-square-mile (8,100 km2) Truckee River Basin. Analytes addressed included nitrogen, reactive phosphate, dissolved oxygen and ten other parameters. Based upon use of the model, some decisions have been influenced to enhance Pyramid Lake water quality and aid the viability of Pyramid Lake biota, including the cui-ui. The dynamic river model was particularly useful for analyzing Truckee River temperature variations, since the cui-ui often swim upstream to spawn, and their fry are vulnerable to elevations in river temperature.
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