Survival, Growth and Recruitment of Larval and Juvenile Razorback Sucker (Xyrauchen texanus) Introduced Into Floodplain Depressions of the Green River, Utah. Final Report

摘要

Floodplains are presumed to be important rearing habitat for the endangered razorback sucker (Xyrauchen texanus). To help recover this endemic Colorado River Basin species, the Upper Colorado River Endangered Fish Recovery Program implemented a floodplain acquisition and enhancement program. Levee removal was initiated in 1996 as one component of this floodplain restoration program. The goal of the Levee Removal Study was to evaluate the system responses to levee removal and make specific recommendations concerning the value of floodplain/river reconnecting for endangered species (specifically razorback sucker) recovery. Razorback suckers were not collected in floodplains during the Levee Removal Study, which may be attributed to the low razorback sucker population in the river. Therefore, data specific to razorback sucker use of the floodplain was not available. This was not a stocking evaluation, rather the stocked fish were used as a tool to learn how razorback sucker may use the floodplains. Age-1 and larval razorback sucker were stocked into depression floodplain wetland habitats along the Middle Green River in northeastern Utah. Age-1 razorback suckers were stocked during the spring of 1999 and 2000 into three floodplain depressions. At the time of stocking each floodplain site contained numerous nonnative fish including: black bullhead (Ictalurus melas), fathead minnow (Pimephales promelas), green sunfish (Lepomis cyanellus) and carp (Cyprinus carpio). The goal of this study was to evaluate if floodplain depressions containing nonnative fishes can still provide effective rearing habitat for naturally produced (wild) razorback sucker.