Razorback Sucker, Xyrauchen texanus , Presence and Reproduction in the Lower Grand Canyon, Arizona

Historically, the Grand Canyon supported the federally endangered Razorback Sucker Xyrauchen texanus, but was considered extirpated by the 1990s. Recent tracking of sonic-tagged adults, and captures of larval Razorback Sucker in the Colorado River inflow of Lake Mead, suggest upstream expansion into the lower Grand Canyon (LGC). In 2014, we conducted six, monthly sampling efforts between Lava Falls (RM 179.2) downstream to Pearce Ferry (RM 280) to determine the presence and distribution of Razorback Sucker in the LGC. Twenty, submersible ultrasonic receivers (SURs) were installed to detect sonic-tagged Razorback Suckers released below Lava Falls (RM 180), Separation Canyon (RM 240), and previously tagged individuals from Lake Mead. Seining was also conducted for small-bodied and larval fish. Telemetry results included contacts with 10 sonic-tagged Razorback Suckers, both from Lake Mead and river-tagged individuals, throughout the study reach. Although no juvenile Razorback Sucker were captured, larval fish sampling yielded 10 total species, primarily catostomids, with over 450 larval Razorback Suckers from 32 unique sites. This work confirmed reproduction, thereby documenting some of the first signs of Razorback Sucker re-establishment in and utilization of the LGC. Future efforts will continue to pinpoint vital spawning areas and assess recruitment of this species.