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vegetation, reservoir plankton, and benthic algae (Angradi 1994). The stable isotope methodology will <br />hopefully prove useful under this Job to identify food web pathways among nonnative piscivores and native <br />fishes. <br />A component was included in a FY 96-97 contract with Colorado State University (Dr. Brett <br />Johnson) to provide a sampling schedule for collection of samples and tissues for preliminary evaluation of <br />the stable isotope technique. This item in this contract simply requested a preliminary schedule for sample <br />collection on the Colorado and Yampa river. The lack of funds to carry out this work on a large scale in <br />either FY 96-97 or 97-98 made development of sampling schedule impractical, however, a description of <br />techniques and a list of references was provided by Dr. Johnson (CSU). However, a smaller scale <br />investigation of this techniques for food components within the Colorado River near Grand Junction is <br />planned for FY 97-98. The use of nonlethal tissue sampling for fish species listed as species of special <br />concern in the river, roundtail chub Gila robusta, flannehnouth sucker Catostomus latipinnis and bluehead <br />sucker Catostomus discobolus, similar to that employed for collecting tissues for genetic analysis, will be <br />employed if feasible. In addition to exploring the stable isotope methodology, I had a discussion with Dr. <br />Dave Rowan, Colorado State University, about bioenergetics applications for Colorado's aquatic food webs <br />using Cesium-137, a globally dispersed radio tracer (Rowan and Rasmussen 1996). This methodology might <br />also offer potential for examining food web pathways in western Colorado rivers. <br />26