Ecological Risk Screening Summary - Lahontan Redside (Richardsonius egregius) - Uncertain Risk

Species that are considered uncertain risk need a more in-depth assessment beyond the Ecological Risk Screening Summary to better define the species’ risk to U.S. environments.

Richardsonius egregius, Lahontan Redside, is a fish that is native to portions of California and Nevada. R. egregius often inhabit deep, quiet waters as well as swift currents of mountain tributaries. R. egregius migrate between breeding and nonbreeding habitats and normally mature in 2-3 years. They can congregate in large schools in lakes and feed opportunistically on insects and planktonic crustaceans. The History of Invasiveness for R. egregius is classified as Data Deficient due to the lack of information on impacts of introduction. There are nonnative populations that have become established in California, but there was no documentation of research into any impacts from those introductions. The climate matching analysis for the contiguous United States indicates establishment concern for this species outside its native range. High match was found across many western areas, including the native range, while low match was found in the eastern portions of the contiguous United States. The Certainty of Assessment for this ERSS is classified as Low due to the lack of information on any impacts of introduction. The Overall Risk Assessment Category for Richardsonius egregius in the contiguous United States is Uncertain.