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<br /> <br />razorback suckers in the middle Green River had declined since 1992 with only about 100 wild <br />razorback suckers remaining in 1999. We discuss several lines of evidence that support the <br />hypothesis of a declining population. We also make recommendations for monitoring remaining <br />wild fish as well as hatchery fish that have been stocked in the Green River to rebuild the <br />population. <br />Razorback sucker distribution.- Sampling since 1992 indicated that razorback suckers <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br />remain in a large portion of the Green River, but that most individuals still occur in the middle <br />Green River from near Jensen, Utah, downstream to Ouray National Wildlife Refuge. <br />Reproduction was documented in summer 2000 in the Yampa River in Echo Park, so a small <br />population of adults must still exist in that vicinity. Given the similar capture rates of larvae in <br />the lower Green River relative to the middle Green River, presence of a few ripe adults, rare <br />occurrence of larvae in samples collected in Green River Valley, and capture of larvae prior to <br />their appearance in the middle Green River, a reproducing population of adults must also occur <br />in that area. Reproduction by razorback suckers has been suspected in or near the San Rafael <br />River (Muth et al. 1998, Chart et al. 1999), but definitive evidence in the form of a relatively <br />large number of ripe fish has proven elusive to this point. <br />The status of outlier populations, particularly those in tributaries, should be conclusively <br />documented immediately so that habitat protection can be implemented. If wild fish play a role <br />in attracting stocked fish to areas where successful spawning has occurred, understanding where <br />successful reproduction by outlier populations is occurring may influence success of hatchery <br />fish in those areas as well. <br />Basinwide sampling; adults, 1996 to 1999.-Basinwide sampling for razorback suckers in <br /> <br /> <br />the Green River contributed to a data set that allowed analysis of the status of razorback suckers <br />21 <br /> <br />