Overview
The Cui-ui (Chasmistes cujus) is a large, prehistoric-looking lake sucker endemic exclusively to the alkaline waters of Pyramid Lake in the Great Basin of Nevada. A sacred species of supreme cultural and historical significance to the Kooyooe Tukadu (Cui-ui Eaters) band of the Northern Paiute people, this ancient survivor can live for more than four decades in desert lake depths.
Biology and Physical Characteristics
Unlike bottom-vacuuming river suckers, the Cui-ui is a midwater filter feeder with a large, terminal mouth that opens forward rather than downward, bordered by thin, smooth lips. Its body is robust and dark brownish-olive to black on the back with silvery-white flanks, turning dark bronze with reddish-copper hues in breeding males. It possesses specialized, densely branched gill rakers adapted for straining microscopic zooplankton from open water.
Behavior and Ecology
For most of the year, Cui-ui school in the deep, cold pelagic waters of Pyramid Lake. In late spring (April and May), mature adults assemble at the mouth of the Truckee River to make a mass spawning run upriver, broadcasting thousands of adhesive eggs over clean, oxygenated gravel beds in the lower river before retreating back into the lake depths.
Conservation and Human Impact
Listed as Critically Endangered by the IUCN and Federally Endangered under the US Endangered Species Act, the Cui-ui was driven to the brink of extinction following the 1905 construction of Derby Dam, which diverted Truckee River water and blocked spawning migrations. Dedicated water-rights acquisitions and a state-of-the-art fish elevator operated by the Pyramid Lake Paiute Tribe have fueled a dramatic recovery.
Interesting Factoid
The Cui-ui is an ancient relic of the Ice Age that survived the drying of prehistoric Lake Lahontan; it can live for over 45 years, waiting out multi-year desert droughts until wet years flood the Truckee River for spawning.