Growth and longevity of the cui-ui and longevity of other catostomids and cyprinids in western North America

Annulus formation on opercula of the cui-ui Chasmistes cujus in Pyramid Lake, Nevada, was validated over an 8-year interval. Many fish were old, as old as 41 years of age, As many as three annuli were hidden (covered by supporting bone) in older fish. Growth was rapid during the first 10 years, slow from 10 to 20 years, and extremely slow or nil after 20 years. Age and growth were strongly correlated for about the first 10 years of life, but less so when fish became sexually mature. Examination of opercula of 15 additional species of large catostomids and cyprinids of western North America revealed that they were older than had previously been thought.