Use of Off-channel Habitats for Rearing Threatened and Endangered Colorado River Fishes
Native fishes of the Colorado River in the western United States include four big-river forms that are listed as endangered by the U.S. Fish and Wildlife Service. These include the razorback sucker, bonytail chub, humpback chub, and Colorado squawfish. Recovery efforts have spent millions of dollars but are failing to recover these species in the river system for many reasons, including introduced predatory fish and the lack of adequate river flow, temperature and sediment loads. We know that some of these species can reproduce in ponds and it is possible that establishment of these species in off-channel ponds along the river corridor could contribute to the recovery effort. The research question is: Can off-channel habitats be used to rear listed species toward their recovery, particularly in areas where river restoration is unlikely, and can a longterm program be developed that will integrate this approach with other ongoing recovery efforts?
Need and Benefit
In many river systems in the western United states, Reclamation is responsible for managing river flows and the aquatic life dependent on that flow. In the Colorado River basin, Reclamation has supported in part a longterm recovery program designed to recover four listed species. However, after two decades of intensive in-river efforts, the four fish remain imperiled. In fact, their status has continued to decline. The ongoing recovery program may be somewhat stymied due to the overwhelming presence of introduced predators, and, the ongoing drought and associated declining river conditions in the western United States. The project proposed here will look into using off-channel habitat for rearing and conditioning the listed species, and formulating this into a successful longterm component of the overall recovery program. Finally then, Reclamation's financial obligations can be reduced. Also, this kind of strategy, if successful in the Colorado River basin, could be used in other watersheds where water supply is low and demand is high.