Razorback Sucker Xyrauchen texanus Research and Monitoring in the Colorado River Inflow Area of Lake Mead and the Lower Grand Canyon, Arizona and Nevada

Authors: Brandon* Albrecht, Ron Keggeries, Ron Rogers, Eliza Gilbert, W. Howard Brandenburg, Adam Barkalow, Steven P. Platania, Mark McKinstry

Year: 2015 (xlvii)

Abstract

For more than 20 years, Razorback Suckers were thought to be extirpated within the Grand Canyon. However, based on past studies and recent movements of sonic-tagged Razorback Suckers from Lake Mead into the lower Grand Canyon (LGC) section of the Colorado River, there are renewed questions regarding the presence of wild individuals and their relationship between the river and reservoir. This collaborative study includes efforts to continue research of Razorback Sucker (all life stages) within the Colorado River inflow of Lake Mead (CRI) combined with the inclusion of sonic telemetry, small-bodied fish community, and larval fish community sampling from Lava Falls downstream to Pearce Ferry, in the LGC (RM 180-280). The specific objectives outlined for these efforts included; (1) conducting larval and small-bodied fish community studies to quantitatively assess annual fish reproduction, spawning, and nursery areas in the LGC, (2) determining if Razorback Suckers are present in the study area and if they associate with specific habitats found within the LGC through the use of telemetry, and (3) identifying habitat associations, relative spawning and reproductive effort, and population trends of Razorback Sucker in the CRI. Specifically, this paper presents findings from the CRI portion of this multi-faceted study, particularly regarding natural recruitment observed within this population, with additional results from the LGC, as informed from small-bodied fish community sampling. Comparisons to historical data will be made, as appropriate. Finally, this research has also provided a means for fairly extensive documentation of young Humpback Chub Gila cypha throughout the riverine portions of the study area, as well as adult Razorback Sucker movement and habitat use within both a lentic and lotic environment.