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<br />22. Potential small-bodied predators of larval razorback sucker. <br /> <br />Authors: JEANETTE CARPENTER arid GORDON MUELLER, U.S. Geological <br />Survey, c/o Bureau of Reclamation, PO Box 25007 (D-8220), Denver, Colorado 80225- <br />0007 <br /> <br />Abstract: Razorback sucker, an endangered big-river species of the Colorado River <br />basin (CRB), has sustained no meaningful recruitment in the past four decades despite <br />consistent observations of spawning adults and larvae. We conducted laboratory <br />experiments to assess the potential predatory impact of small-bodied non-native <br />predators, such as small cyprinids andjuVienile game fish, on razorback larvae. We tested <br />ten non-native fish: adult red shiner, threadfin shad, and fathead minnow; age-l yellow <br />bullhead; and age-O rainbow trout, bluegill, largemouth bass, common carp, green <br />sunfish, and channel catfish. Every species tested ate razorback sucker larvae. The most <br />aggressive non-native predators on razorback larvae <15 mm TL were adult red shiner <br />(<65 mm); and age-O rainbow trout (<51 mm), green sunfish (<62 mm), channel catfish <br />(<86 mm), and common carp (<75 mm). Age-O largemouth bass <80 mm TL consumed <br />at a moderate rate razorback juveniles that were nearly half their size (range=34-39 mm <br />TL). This study illustrates that early life stages of native fish in the CRB are highly <br />vulnerable to small non-native predators that have easy access to shallow nursery <br />habitats. Our results suggest that efforts tQ manage non-native fish for improving native <br />fish recruitment in the CRB should target all life stages of non-native fish, not just large- <br />bodied fishes. <br /> <br />23. Comments on strategic approaches to floodplain management for endangered <br />fishes in the Green River subbasin, <br /> <br />Author: TIM MODDE, Colorado Fish ~roject, U.S. Fish and Wildlife Service,Vemal, <br />Utah. <br /> <br />Abstract: A strategic approach to floodplain management is presented that outlines a <br />systematic process identifying biological needs and a sequence of management actions. <br />The Recovery Program has identified broad directives relative to the floodplain <br />management, but greater specificity is needed before site action plans can be <br />implemented. The approach I present allows a means of measuring success at individual <br />sites and provides a more precise means of determining the value of floodplain wetlands <br />n5 recovery razorback sucker and bonytail in the Green River subbasin. <br /> <br />20 <br />