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<br />000905 <br /> <br />floodplains, riffles, sloughs, bridge abutments, etc.). While it <br />may be possible that habitat requirements of a single generalist <br />species would be adequate to model habitat of all other species <br />in small rivers, "organisms in large rivers often show a greater <br />tendency toward habitat zonation and isolation and the use of <br />specialized habitat types" (Stalnaker, et al. 1989). Overall, <br />generalist species (those with a wide range of habitat <br />preferences) may be relatively insensitive to flow changes <br />(Leonard and Orth 1988), though other factors may also influence <br />their use of habitat. <br /> <br />The single-species approach likely is not appropriate for <br />modeling forage fish requirements on the Platte River. Much <br />research has been completed on Platte River fish and associated <br />habitats since the species experts met in 1986. Due to the <br />availability of this new information, a different approach to <br />modeling habitat should be used. <br /> <br />Guildina approach <br /> <br />A mOdeling approach that addresses the fish community should be <br />used to maintain the fishery resource within the Platte River. <br />This concept has been adopted by the Service, Nebraska Game and <br />Parks, and the Biology Workgroup of the Joint Study for <br />endangered species. <br /> <br />The Service has recommended a "guild" approach to modeling <br />fishery habitat in the Platte River (Fannin 1990). A guild is "a <br />group of species which exploit the same class of environmental <br />resources in a similar way" (Root 1967, in Leonard and Orth <br />1988). This approach can be used to address the habitat needs of <br />the central Platte River fish community. The advantages of <br />guilding are: a) it addresses the greater habitat partitioning <br />in larger rivers; b) it reduces potential errors of applying a <br />single set of habitat curves to the variety of habitats in a <br />large river, if guild representatives are selected properly, and <br />c) it more likely permits recommendations for instream flows <br />which are compromises among the needs of all species. Though all <br />HSI models are simplifications of natural systems, the guild <br />approach is less a simplification than the single-species <br />approach because the guild incorporates more than one species. <br /> <br />Figure B1 (Appendix B), shows a composite curve for 4 species <br />(plains killifish, sandshiner, juvenile channel catfish, and <br />adult common carp) of fish for the reach of river from the J-2 <br />return to Chapman. The data used to produce this composite curve <br />was collected and partially analyzed by Chadwick and Associates <br />(1989). Despite some limitations of the field techniques used to <br />gather this data, this information constitutes some of the only <br />PHABSIM data fully developed for the central Platte River at this <br />time and, therefore, should be considered when developing <br />instream flow recommendations. If additional and improved <br /> <br />8 <br />