Successful management of Stewart Lake wetland as a nursery for endangered razorback sucker, Xyrauchen texanus, on the middle Green River, Utah

Authors: Robert Schelly, Matthew J. Breen, Krissy W. Wilson

Year: 2014 (xlvi)

Abstract

In the Colorado River Basin, endangered razorback sucker, Xyrauchen texanus, have been impacted by impoundment-related habitat loss and the introduction of nonnative species. For decades, survival of wild-spawned razorback suckers to juvenile stages has been negligible, and populations have been maintained by stocking of hatchery-raised fish. Here we report on successful efforts to manage Stewart Lake, a gated wetland on the middle Green River near Jensen, Utah, as a nursery for wild-spawned razorback sucker, using a trap and weir system to exclude adult nonnative fishes during filling. In a cooperative multi-year effort by Federal and State agencies called the Larval Trigger Study Plan, light trapping is being used to detect the presence of larval razorback suckers in the river, triggering increased releases from Flaming Gorge Reservoir so as to realize peak flows during larval drift. In early June, 2014, Stewart Lake was filled during this high water period to maximize entrainment of razorback sucker larvae. The growth and distribution of razorback suckers in the wetland was monitored throughout the summer, with the gate opened for drawdown in early September. Using a trap to sample fish exiting the wetland into the river, hundreds of juvenile razorback suckers, up to 168 mm in total length, were observed. The management of Stewart Lake thus creates suitable nursery conditions for the successful recruitment of razorback suckers, which will be critical to the recovery of this species.