Laserfiche WebLink
<br />COLORADO RIVER RECOVERY PROGRAM <br />FY 2002 ANNUAL PROJECT REPORT <br /> <br />RECOVERY PROGRAM <br />PROJECT NUMBER: C-6-RZ <br /> <br />I. Project Title: <br /> <br />Evaluation of survival and growth of larval razorback suckers stocked into floodplain <br />depressions of the Middle Green River. <br /> <br />II. <br /> <br />Principal Investigator(s): <br /> <br />Kevin D Christopherson <br />Utah Division of Wildlife <br />Northeast Regional Office <br />152 East 100 North <br />Vernal, Utah 84078 <br />Phone: (435) 789-3103; Fax: (435) 789-8343 <br />E-mail: kevinchristoDherson@utah.gOV <br /> <br />Tim Modde <br />Vemal Colorado River Fish Project <br />U.S. Fish and Wildlife Service <br />Vernal, Utah 84078 <br />Phone: (435) 789-0354; Fax: (435) 789-4805 <br />E-mail: tim modde@fws.gov <br /> <br />III. Project Summary: <br /> <br />Floodplain wetlands are considered important rearing habitat for razorback suckers. <br />However, the presence of large nonnative fish populations in floodplain habitat may hinder or <br />prevent survival of entrained larval razorback suckers. Nonnative fish are considered a primary <br />factor preventing recruitment ofrazorback suckers in the Upper Colorado River Basin. An <br />earlier study, conducted by the Utah Division of Wildlife (UDWR), evaluated stocking of larvae <br />and juvenile razorback suckers into floodplain wetlands with existing nonnative fish populations. <br />During this study juvenile razorback sucker growth 'and survival was excellent, however larval <br />survival was not detected. <br /> <br />Densities of nonnative fish are fairly low in floodplain wetland habitats during the first <br />inundation period following an event that eliminates or "resets" nonnative populations in a site <br />(i.e. draught). Nonnative fish entering floodplain wetland habitats from the river during this <br />initial inundation period reproduce and fish populations increase rapidly. High densities of <br />nonnative fish remain in floodplain sites until the next "reset" event. The best opportunity for <br />larval razorback sucker survival and eventual recruitment in floodplain habitats may occur the <br />first year following a "reset" of the nonnative fish population. Larval razorback suckers that <br />enter floodplain sites the first year after a "reset" will not have to face large existing populations <br />of nonnative fish, which may help survival through their most vulnerable period. <br /> <br />(-6 rz page 1 <br />