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following stocking. Radiotagged razorback sucker exhibited similar movement <br />patterns and behavior following stocking at different sites in the San Juan River <br />(Ryden and Pfeifer 1995; 1996). The mean downstream displacement for radiotagged <br />razorback stocked in the spring in the San Juan River was 10.5 miles, compared <br />to 19.3 miles for razorback sucker stocked in the Upper Colorado River and 14.3 <br />miles for fish stocked in the Gunnison River. The mean downstream displacement <br />for radiotagged razorback sucker stocked during the fall of 1994 (54.0 miles) and <br />1995 (58.2 miles) in the San Juan River was greater than those stocked in the <br />spring (Ryden and Pfeifer 1995; 1996). <br />Thirty-four, adult, pond-reared razorback sucker, implanted with both <br />internal and external sonic tags, were stocked in the San Juan River inflow area <br />of Lake Powell in the fall of 1995 and their movements monitored (Karp and <br />Mueller 1996). During the 11 months that contact was maintained, several of <br />these fish exhibited fairly long up- and downstream movements following stocking; <br />others made only one-way movements. Of the fish contacted, all appeared to <br />remain in the inflow area of Lake Powell in the Lower San Juan River following <br />release; none of the tagged razorback sucker made obvious downstream movements <br />into Lake Powell. One fish, after moving downstream 3 miles then moved upstream <br />43 miles; another fish initially moved downstream 19 miles and then returned <br />upstream 29 miles. Both of the upstream movements occurred during spring, and <br />these researchers suggested that not only were the fish seeking certain types of <br />habitats but that movements may be possibly related to spawning behavior. <br />The initial downstream movement of stocked fish may be in response to these <br />fish searching for adequate food resources and riverine habitat (Personal <br />communication, Edmund Wick) or fright and traumatic, behavioral stress related <br />to handling, stocking, and exposure to a new environment (Personal communication, <br />Gordon Mueller). <br />Once passage to upper reaches is more generally available, another <br />alternative would be to stock in lower reaches like lake inflows or extensive <br />connected pond areas in lower stream reaches. U. S. Geological Survey (USGS) <br />researchers plan to further investigate the utility of stocking captive-reared <br />razorback sucker in lower stream reaches near inflow areas (San Juan River arm <br />of Lake Powell) where food availability and productivity is high. Higher water <br />temperatures and greater food availability may make lower stream reaches better <br />for reintroducing captive-reared razorback sucker until more off-channel and <br />floodplain habitat in upper stream reaches are made accessible (Personal <br />communication, Edmund Wick). Stocked razorback sucker can remain in lower <br />velocity, food rich, and warmer feeding areas during reintroduction and move <br />upstream to better spawning habitat when they feel the urge to explore and expand <br />their range. They can learn the river from downstream to upstream instead of <br />being forced downstream by high velocity, low food density, and competition with <br />other river suckers. <br />Reducing fright and traumatic stress related to stocking may be an <br />important factor in the ultimate survival of razorback sucker. USGS researchers <br />will monitor the response and survival of captive-reared razorback sucker stocked <br />in new riverine environments. The test will determine if post-stocking <br />behavioral stress can be reduced and survival increased if fish are allowed to <br />slowly acclimate in a backwater before migrating to other riverine habitats. <br />15