Floodplain Wetland Suitability, Access, and Potential Use by Juvenile Razorback Suckers in the Middle Green River, Utah

Abstract

Abstract In the upper Colorado River basin, razorback suckers Xyrauchen texanus primarily occur as adults in low-gradient reaches of rivers or as juveniles or subadults in adjoining floodplain depressions. During the high-water years of 1995 and 1996, a number of habitat variables—zooplankton density, water temperature, quality, and depth, and vegetative cover—in a Green River floodplain depression were favorable to age-0 razorback suckers and other fishes. Conversely, main-channel habitats were not suitable as rearing sites due to lower temperatures, less food, and ineffective cover. During the spring runoff in 1995 and 1996, larval razorback suckers were found in the river after floodplains were isolated from the Green River. Although favorable nursery sites are located off-channel, the connectivity of the river and floodplain did not last long enough for all razorback sucker larvae to access these areas. Maintaining the connectivity of the floodplain to the river via levee removal and adequate flood du...