Near the interface with the San Juan River, the receding waters of Lake Powell have left in its tracks an 18-foot tall waterfall, referred to as the Piute Farms Waterfall. Since 2001, this feature has created a barrier to upstream fish movement, keeping nonnative fishes of Lake Powell out of the San Juan River. The waterfall does come with consequences, severing critical habitat of two of the basin’s endangered species: razorback sucker and Colorado pikeminnow. Recent estimates indicate that a population of >800 razorback sucker migrate to the area below the waterfall each spawning season. The waterfall effectively shortens the spawning migration, reduces the overall reproductive potential, and limits gene flow among populations.
In an effort to restore spawning migration connectivity, researchers from Kansas State University (KSU) and the U.S. Bureau of Reclamation (USBR) annually trap razorback sucker below the waterfall and transport them 2-4 km upstream in a Jon boat. In the spring of 2021, biologists from 8 agencies (KSU, USBR, U.S. Fish and Wildlife Service, FISHBIO Consultants, Utah Division of Wildlife Resources, Jicarilla Apache Nation, University of Arizona, and National Park Service) captured fish for two weeks below the mist of the Piute Farms Waterfall. Although the winds were strong, they were rewarded with 210 razorback sucker, 43 Colorado pikeminnow, 159 flannelmouth sucker, and 89 bluehead sucker. All of which were given passage above the waterfall. In addition to typical electrofishing techniques, an experimental seining corral and fyke trap (fabricated by FISHBIO) assisted in the capture of native suckers.
Throughout 2020 and 2021, researchers are using radio telemetry to assess movement behavior following passage efforts. A combination of stationary radio antennas, aerial surveys, and raft-mounted surveys are used to monitor locations of radio-tagged razorback sucker throughout the year. Preliminary results indicate transported individuals use upstream habitats throughout the spawning season, however, their contribution to the spawning population remains unclear. Researchers at Southwestern Native Aquatic Resources and Recovery Center will use genetic tissue from larvae and transported individuals to provide parentage analysis, shedding light on the efficacy of this management action.