Juvenile and adult razorback sucker research and monitoring in Lake Mead, Nevada and Arizona.

Authors: Zachary Shattuck, Brandon Albrecht, Ronald Rogers

Year: 2013 (xlv)

Abstract

The recruitment, movement patterns, habitat use, and population trends of adult razorback sucker, Xyrauchen texanus, in Lake Mead have been studied in some capacity since 1996. As past study has shown, Lake Mead is unique in the continued recruitment of wild razorback sucker and the presence of juvenile individuals. Several methodologies were employed in long-term monitoring during the 2012-2013 field season to assess adult reproductive activity and population demography including; sonic telemetry, trammel netting, nonlethal aging, and larval fish surveys. The collection of these data aided in the identification of primary spawning areas, successful reproduction, and continued recruitment with a number of new, wild razorback suckers captured in Las Vegas Bay, Echo Bay, and the Muddy River/Virgin River inflow area. Additionally, efforts to specifically target juvenile razorback sucker in Lake Mead, utilizing sonic-tagged juvenile individuals, were employed to understand why Lake Mead razorback suckers are able to demonstrate natural recruitment. Movement and contact locations of sonic-tagged juvenile razorback suckers were used to help to characterize the physicochemical attributes of areas where sonic-tagged juveniles were detected. Furthermore, a number of methods were used to describe the associated fish community and sample for other conspecifics. Following this approach, new, wild, razorback suckers were collected in association with sonic-tagged juvenile individuals and seasonal movement and habitat use were more completely described in Las Vegas Bay, Echo Bay, and the Muddy River/Virgin River inflow area. Continued research concentrating on this rare life stage will hopefully aid in the understanding of recruitment in Lake Mead, with conservation applications for the species throughout the Colorado River basin.