Lake Mead razorback sucker recruitment, population trends, and relationships to recovery

Authors: Brandon Albrecht, Paul Holden, Ronald B. Kegerries, Ronald Rogers

Year: 2010 (xlii)

Abstract

An ongoing razorback sucker (Xyrauchen texanus) research project on Lake Mead, Arizona and Nevada has been funded by the Southern Nevada Water Authority and the U.S. Bureau of Reclamation for 14 years. This study continues to document the presence of actual, wild razorback sucker recruitment in the form of young, sexually immature individuals. Continued recruitment denotes that the Lake Mead razorback sucker population is an anomaly in terms of razorback sucker persistence throughout the Colorado River drainage, despite similar non-native fish composition and densities as other locations. Fin ray aging data and back-calculation techniques have indicated that recruitment of razorback sucker in Lake Mead has occurred nearly every year since the 1970s. Cover features within Lake Mead appear to be responsible for this continued recruitment. The continued observation of natural razorback sucker recruitment has spurred recent interest in Lake Mead in terms of recovery populations/goals. Recovery goal discussions tend to center around population numbers and as such, we present the best available information depicting current population trends associated with Lake Mead razorback sucker. Continued monitoring efforts on Lake Mead should help to ascertain if recruitment events continue, to better understand the overall population size, and to help more fully understand how to enable this unique trend in other locations within the historic range of the species.