If you build it, can they get there? Managing flows and habitats to improve recruitment of wild Razorback Sucker, Xyrauchen texanus

Authors: M. Jones, Kevin Bestgen, David Speas, Matthew Breen, Christian Smith, Robert Schelly, Michael Partlow, Saidee Hyder

Year: 2024

Abstract

The Upper Colorado River Endangered Fish Recovery Program has been working since its inception in the 1980s to recover Razorback Sucker in the Colorado and Green river subbasins. One component of that work has been to restore floodplain wetland habitats and allow Razorback Sucker to access those sites during early life stages. In the 1990s, the habitat program focused on reconnecting wetlands by breaching levees, but this action alone was not sufficient to increase Razorback Sucker in these habitats. Further research in the early 2000s indicated Razorback Sucker needed spring peak flows to carry larvae into the floodplain, leading to the Larval Trigger Study Plan (LTSP). The LTSP proposed timing spring peak flow releases from Flaming Gorge Dam with the presence of Razorback Sucker larvae using real-time monitoring. These releases, coupled with habitat management and water control capabilities, are intended to move wild-spawned Razorback Sucker larvae from main channel river habitats into floodplain wetland sites. Ideally, large non-native fish are prevented from entering this sites during this period, although some small-bodied non-natives are typically present. Through a combination of habitat development and flow management, the Recovery Program is trying to facilitate Razorback Sucker completing their life cycle in the wild. Since the first implementation of LTSP in 2012, biologists have consistently encountered wild, juvenile Razorback Sucker in these wetland sites. Between 2012 and 2023, we have captured 9,269 of these wild-produced, age-0 fish. The Recovery Program has also expanded the number of wetland sites being managed to include sites on both the Green and Colorado rivers, and we continue to explore candidate sites to expand the concept. Currently there are six sites in regular operation, with another scheduled for construction near Grand Junction, Colorado and one in the design phase on the San Juan River. Bonytail have also used these wetlands with some success when they have been stocked in these locations, which will be covered in other talks during the symposium.