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<br />= <br /> <br />...:,=. ~\J <br /> <br />. .c <br /> <br />Nankoweap Creek and the magnitude of dally discharge <br />fluctuations . <br /> <br />8.-5.1p. There is no significant relationship between trout <br />availahility, trout access, bald eagle presence and abundance. or <br />bald eagle foraging success in the mainstream or Nankoweap Creek <br />and the magnitude of minimum discharges. <br /> <br />6. Question: How do discharge fluctuations and rates of <br />change in fluctuating discharges affect other fish, especially <br />native fish species? Do the USFWS Conservation Measures <br />adequately address this question? <br /> <br />8.-6.1. There is no significant relationship between the <br />population dynamics (including short-term abundance of early life <br />staqes and potential predation relationships) of native <br />(especially the humpback chub) and introduced fish species in the <br />mainstem Colorado, including mainstem backwaters and the <br />confluence of the Little COlorado, and the magnitude of <br />fluctuations, minimum discharges and rates of change of <br />fluctuating discharges. <br /> <br />Justification: Native fish species, especially tne hu~pback <br />chub, are found in the mainstem Colorado River. but their <br />potential for reproduction and survival is thouqht to be <br />dependent on tributaries and backwaters. The availability <br />ot appropriate habitats tor reproduction and food sources in <br />the tributaries and backwaters may be directly related to <br />influences from the various discharge levels and volumes in <br />the aainatem. Also, availability ot appropriate and <br />sufficient food sources in the mainstem may be influenced by <br />discharqe variables. Therefore, potential success of the <br />native fish spec!es in the mainstem Colorado may be directly <br />related to their ability to (1) accommodate the transition <br />between tributary/backwater and mainstem and (2) <br />successfully teed in the mainstem. survival of the native <br />fish species may also depend on their interrelationships <br />with other fish species, especially introduced species that <br />have been introduced into the Colorado River system. <br /> <br />InforJlation .eel1s: Resource and food availability in the <br />tributaries, backwaters and mainstem need to be determined. <br />The ability of larval staqes to survive both tributary <br />lbackwater habitats and transition to the cold water <br />mainstem needs to be determined (e.g., the latter through <br />laboratory studies). Adult maintenance in the mainstem <br />should be measured through periOdic sampling, and <br />reproductive success in appropriate hahitats needs to be <br />measured. Representative tributaries (especially LCR, <br />Kanab, Havasu and Paria) and backwaters will be selected for <br /> <br />10 <br />