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CHAPTER IV ENVIRONMENTAL CONSEQUENCES B. Rare and Endangered Fishes ENVIRONMENTAL CONSEQUENCES OF THE PROPOSED ACTION Overview The goal of the Proposed Action is to recover and delist the endangered Colorado squawfish, bonytail chub, and humpback chub, and to manage the razorback sucker so that it does not require the protection of the Endangered Species Act. The following paragraphs discuss how each of the five recovery , elements will protect, manage, and recover the rare fish. [Note: If the razorback sucker is listed, it will be treated as the other endangered species under the Proposed Action.] Habitat Management Colorado sq-uawfish.--Changes in flow regimes could affect all life history , stages of the Colorado squawfish. Young Colorado squawfish appear particularly sensitive to flows. The recommended summer releases from Flaming Gorge Dam are expected to increase the amount of available nursery habitat for ' Colorado squawfish in the Green River. However, reduced summer releases in an average or wet year will result in increased fall releases or fall/winter releases. These higher flows might have an adverse impact on habitat used by ' young Colorado squawfish during the early winter period. This potential adverse impact is being investigated by current research studies investigating year-round flow requirements for all life history stages of rare fishes below Flaming Gorge Dam. When studies are completed, a dam release regime to improve Colorado squawfish recruitment and survival will be developed as a result of Section 7 consultation. Humpback Chub, Bonvtail Chub, and Razorback Sucker.--Flaming Gorge Dam Releases from Ruedi and/or Green Mountain Reservoirs will ensure more water is available for habitat for endangered fishes in the Colorado River between Palisade, Colorado, and the confluence of the Gunnison River during the Colorado squawfish spawning and recruitment period. Releases from the Aspinall Unit are expected to maintain river flows for the fish in dry years. For those reaches where Federal dams cannot ensure needed flows, water rights will be acquired to ensure critical flows needed by the rare fish. releases could affect the humpback chub and razorback sucker in the Green River downstream from the confluence with the Yampa River. Flows from Ruedi Reservoir and the Aspinall Unit could affect these species in the Colorado River downstream from the confluence of the Green and Colorado Rivers. Flow requirements for the various life stages of these rare fishes are not well enough known to predict the effect of these flows. However, studies on these fishes in the Colorado River are planned relative to operation of the Aspinall Unit. Information from these studies will help refine future dam releases to benefit the rare fishes. IV-B-1