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<br />The key to survival of bony tail in alluvial reaches is survival of larvae. Recent Recovery <br />Program studies have illustrated that survival of adult and juvenile life stages of razorback sucker <br />in floodplains in the presence ofIarge numbers of nonnative fishes is relatively high (Modde <br />1997; UDWR unpublished data). The obstacle to recovering bony tail may be survival of larvae in <br />wetland habitats. The November 200] Recovery Program wetland restoration workshop in <br />Denver, Colorado, promoted the concept of "resetting" floodplains as the most probable scenario <br />in which larval razorback sucker and bony tail were likely to survive. This scenario mimics the <br />conditions existing during the years large numbers of razorback sucker were produced in lower <br />basin reservoirs as they were filling (Minckley et al. 1991). This study will test the concept of <br />"resetting" floodplains for the first time using stocked larval bony tail. <br /> <br />IV . Study Schedule: 2002-2004 <br /> <br />V. Relationship to RIPRAP: <br />GREEN RIVER ACTION PLAN: MAIN STEM <br />II. Restore habitat. <br />II.A. Restore and manage flooded bottomland habitat. <br />II.AJ. Implement levee removal strategy at high-priority sites. <br />II.AJ.c. Evaluation. <br /> <br />VI. Accomplishment of FY 2002 Tasks and Deliverables, Discussion of Initial Findings and <br />Shortcomings: <br /> <br />The spring peak flows of the Green River were very low in 2002, and prevented <br />connection of the floodplains to the river. As a consequence, the original plan of investigating <br />survival of stocked bony tail in multiple wetlands was canceled. An alternate plan of pumping <br />water into a single wetland with enclosures stocked with bony tail and nonnative fishes was <br />adopted. The Stirrup, a 20-acre wetland, was pumped to a maximum depth of approximately ] 00 <br />cm in the spring between April 25 and May 3, 2002. On May 8, 2002, bony tail were stocked into <br />three enclosures placed in the wetland in the following numbers: 5,250 fish in the control pen <br />(0.01 acres); 2],250 fish in the low-density pen (0.25 acres);and 45,000 in the high-density pen <br />(0.25 acres). In the low-density pen 75 fathead minnow, 42 red shiner, 16 black bullhead, 12 <br />green sunfish and 4 carp were stocked. The high-density pen received 81 fathead minnow, 37 <br />red shiner, 15 black bullhead, ] 8 green sunfish and 3 carp. Zooplankton densities were <br />monitored biweekly and water quality parameters were monitored over a 24-hour period several <br />days per week between stocking and the end of the experiment on August 13, 2002. <br /> <br />At the end of the experiment, 898, 865, and 363 fish were estimated respectively from the <br />control, high-density, and low-density pens. Survival estimates for the control, high-, and low- <br />density pens were 22.0%, 1.9%, and 1.7%, respectively. Fish removed from the pens were <br />released into the wetland (outside of the pens). Before initiating collections within the study <br />pens at the end of the study, fYke net collections showed that several thousand bony tail had <br />escaped from the pens and were alive in the wetland at-large. The bony tail that had escaped <br /> <br />C-6bt page 2 <br />