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<br />PI - , <br /> <br />Sub-objective l.a.: Evaluate effects of nonnative fishes on young <br />razor backs in a simulated floodplain environment. <br /> <br />This sub-objective gets at what may be the primary obstacle to <br />recovery. Of the 42 species of nonnative fishes in the upper <br />Colorado River basin, many are known piscivores which inhabit the <br />same slackwater habitats preferred by young endangered fishes. <br />Studies conducted under sub-objective l.a. will be designed to <br />answer the questions: <br /> <br />-Can young razorbacks survive and grow in the presence of nonnative <br />fishes? <br />-Do flooded vegetative cover and/or turbidity enhance survival? <br />-When spring flows rise, are razorback larvae the first fish to move <br />into flooded areas? <br />-When spring flows subside, are razorbacks the first ones out and, <br />therefore, less vulnerable to becoming stranded in isolated pools <br />than are other species? <br />-Can floodplain habitats be designed and managed to favor endangered <br />fishes over nonnative fishes? <br /> <br />Sites like Old Charlie, Leota, floodplain terraces, and hatchery <br />ponds will be used to answer these questions. In most cases, we <br />will begin with smaller-scale experiments for better control. <br /> <br />2. Maximize recruitment and persistence of razor backs and other native <br />fishes in the long term through restoration and adaptive management of <br />floodplain functions. <br /> <br />This is the long-term objective. We may know the conditions which can <br />"maximize recruitment and persistence of razorbacks", but we do not know how <br />to achieve those conditions outside of the hatchery or rearing-pond <br />environment. For example, how do we manage flows, sediment, contaminants, <br />nonnative fish predators, water temperatures, water quality, and food <br />densities in a "natural ecosystem"? Only field experiments (i.e., the Or" <br />word, "research") will help us answer those questions. This is where <br />objective 2 comes into play. We can raise razorbacks in floodplain ponds and <br />hatchery ponds, and forever stock them into the river. But the goal of this <br />program is "to restore...natural floodolain functions that suooort recovery of <br />the endangered fishes". Therefore, our efforts must eventually lead to a <br />"natural" (or seminatural) system where the endangered fishes can take care of <br />themselves. This may require some manipulation of flow regimes, some initial <br />excavation and construction of habitat enhancement structures, some nonnative <br />management measures, some contaminants remediation measures, etc. Stocking <br />may be required in the early stages, to evaluate restored habitats, to reseed <br />the Colorado and Gunnison rivers, and to help build the populations to a <br />sustainable size. The ultimate goal, however, is "self-sustaining" <br />populations. <br /> <br />4 <br />