9681 - Laserfiche WebLink

Home Browse Search

2) Population "enhancement". Reopening or reestablishing historic areas of river enabling adult fish to spawn; or enabling fish to spawn downstream of the barrier and return upstream after spawning. To be used if this biologically benefited the squawfish population, i.e., if it contributed significantly to the total reproductive success of the population. Fish passageways, then, should only be seriously considered when it can be demonstrated that at least one of the above items will benefit the population. 4. Biological problems using a fish passageway: 1) If the instream barrier does not have a spillway feature, downstream fish movement of all size classes would be depend on the fish's ability to locate and use the fish passageway to gain downstream access. Fish moving downstream originating from upstream reaches that would have to pass through a reservoir may have difficulty in locating the fish passageway or may never locate the passageway and may become reservoir residents. In instances where a reservoir exists upstream of the instream barrier, fish that successfully use a fish passageway may become disoriented in the reservoir and may never continue to move upstream and may become full-time residents in the reservoir. These fish may become for all intense and purpose "functionally" or biologically (i.e., fish may fail to reproduce or fail to comingle with other riverine squawfish) isolated from the population. An example of this is Taylor Draw. 2) It is not recommended that fish passage be provided in reaches that may be on the fringe of the squawfish's historic range, or if it is not known if successful spawning did or would occur there. Cited as an example of this is the river reach near the current Price Stub Dam. The probability that fish will use the fishway might be high, but the number of fish using the fishway at this site may be quite low. Additional information, such as sampling the plunge pool during the time when radio-tagged fish frequent the area to note any additional squawfish in the area, would be prudent. In addition to this, moving fish over the Price Stub Dam either actively or passively, would open up only about five additional river miles of potential habitat. This is because another medium-size barrier upstream of the Price Stub, Government Highline Diversion, would block any further upstream movement. Constructing a fish passage facility to allow passage to only five miles of additional, potential habitat cannot be considered biologically or cost effective. 3) There is no guarantee that if squawfish were passed over Redlands that they would successfully spawn in the Gunnison River, and thus be recruitment to the population. It is speculated that providing passage for squawfish upstream of the Redlands Diversion would allow these fish to possibly spawn there. There is some circumstantial evidence to suggest that fish did once spawn there, even after the Diversion was in place. However, it is unknown if fish will spawn in this reach now, because water 13