Razorback sucker (Xyrauchen texanus) monitoring on Lake Mead Nevada and Arizona, 2011

Authors: Ronald Rogers, Zachary Shattuck, Brandon Albrecht, Paul Holden

Year: 2011 (xliii)

Abstract

For the 15th consecutive year, distribution, recruitment, and population trends of wild razorback sucker (Xyrauchen texanus) in Lake Mead Nevada and Arizona were monitored with funding provided by the Bureau of Reclamation and Southern Nevada Water Authority. In order to assess this unique, wild razorback sucker population, several techniques including: sonic surveillance, trammel netting, and larval fish surveys were employed during the winter/spring spawning season in 2011. Razorback sucker appeared to have had a successful spawning year in 2011. A total of 86 wild razorback sucker were captured from three long-term monitoring sites and 72 new, wild razorback sucker fin rays were collected for aging analysis. To date, 608 wild razorback suckers have been captured from Lake Mead. Additionally, 360 fin ray sections have been collected and analyzed; helping to illustrate the continued recruitment of wild razorback sucker from 1978 to 2008. The 2005 year-class continues to be a strong year for recruitment in Lake Mead. Increases in lake level due to high flow events in 2010-2011 may have helped to provide cover in the forms of turbidity, inundated vegetation, and large woody debris for all life stages of razorback sucker. The increase of lake level may provide physical and environmental factors necessary to allow a pulse in recruitment for the 2011 year-class. Future research will provide data to lend comprehension into this possibility. While current studies have provided a great deal of insight into the habitat use of adult fish, only limited information pertaining to subadult and young of year razorback sucker nursery habitat has been identified in Lake Mead. Continued study should focus on this critical life stage to aid in the understanding of recruitment on Lake Mead and perhaps enable this trend within the Colorado River Basin.