6012 - Laserfiche WebLink

Home Browse Search

• f, r time cpn coincide. Temperature modeling with flow indicates that at Black Rocks flows of 7,000-13.000 cfs in May sl~oi~ld be maintained to keep temperatures at about 13-15°C for humpback spawning (Appendix B). However, other information shows spawning at 16-18°C. As stated above, more work needs to be done on effort of temperature on spawning separation of humpback and roundtail chubs. A high flaw is also needed at critical areas in order to flush sediment from the spawning areas and to maintain the integrity of the present river channel. We recommend that at least once every 3 years, a high peak flow be provided at the key spawning areas on the river. This peak should be of sufficient duration to flush sediments from the spawning substrates and maintain the present habitat at the aforementioned key areas. Magnitude of the peak flow should be determined by documenting spawning at various flow levels. Without this verification, we recommend an average or above average peak flow volume based on the averages before 1960 keyed to Black Rocks in the Colorado River and Ouray in the Green River (Table 3). Table 3. Peak flows needed once every three years in the Green and Colorado Rivers for maintenance of key Colorado squawfish and humpback chub habitat based on peak flows average before 1960. River and Location Peak Flows 17eeded/cfs duration Colorado River, Black Rocks Area (River Mile 136) 2 weeks Green River, Ouray Area 2 weeks (River Mile 143) Recovery of Target Species The flow recommendations presented in this report and much of the associated data has been directed toward the survival of the species under present-day conditions. However, the goal in working with these endangered fish should be recovery and subsequent delisting by FWS. There is now enough information on all the target species, with the exception of the bonytial chub, to initiate active management recovery programs. Our hatchery work has shown that all the target species can be propagated for reintroduction or supplementing present populations. Survival of stocked Colorado squawfish in the Colorado River has been documented and an introduction of humpback chub is now under study.