7282 - Laserfiche WebLink

Home Browse Search

to the fishes. As part of a 3-year study, and in conjunction with the Service, Reclamation is examining the relationship between releases from Flaming Gorge and the downstream formation of useful backwaters for larval squawfish (see Section 4.1.6.3). Backwater habitat also can be developed artificially: (a) by connecting existing gravel pits or ponds to the river, or (b) by physical construction to simulate the depth, velocity, and substrate characteristics found in naturally occurring backwaters. 4.2.2 Spawning Habitat Usable spawning areas are essential to the continued existence and the recovery of all four Colorado River fishes. Confirmed and suspected spawning areas of the Colorado squawfish and the humpback chub have been located. Some information is available on natural spawning habitat for the razorback sucker, but none is available for the bonytail chub in the upper basin. Management of spawning habitat for the squawfish and other species could include: (a) improving access to existing spawning areas in river segments that apparently are not being used (e.g., by developing fish passage structures - see Section 4.2.4); (b) reintroducing eggs or larvae into unoccupied, but suitable, spawning habitat; (c) modifying instream characteristics to create spawning habitat; or (d) constructing spawning habitat within the natural stream channel or in modified side channels (also see Section 4.3.2). 4.2.3 Habitat Created by Jetties Jetties redirect flow by increasing velocity and deepening the channel at the end of the jetty. Eddies are formed upstream and downstream of the structure, causing deposition of sediments due to decreased stream velocity. It is believed that adult squawfish over-winter in the Yampa in bends of the river which, like jetties, create increased water velocity and deepened channels. It is possible, therefore, that jetties could be constructed to simulate this habitat. The development of jetties, however, may have a negative effect by enhancing habitat for nonnative predatory fish that use the same types of pools. Jetties should not be constructed in spawning areas or in areas that might be occupied by young squawfish subject to predation. As the first step in evaluating the use of jetties, studies should be performed to determine the extent of use of existing jetty-created habitat by both squawfish and nonnatives and to monitor the interactions between squawfish and the nonnative species. 4.2.4 Fish Passaae Facilities Colorado squawfish are known to migrate essential to different life stages during in the Upper Colorado River Basin, such River and Taylor Draw Dam on the White up to 200 miles to utilize habitat different times of the year. Dams as Flaming Gorge Dam on the Green River, have blocked the passage of 4-12 I 1 I rl