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Floodplains are presumed to be important rearing habitat for the endangered razorback sucker (Xyrauchen texanus). To help recover this endemic Colorado River Basin species, the Upper Colorado River Endangered Fish Recovery Program implemented a floodplain acquisition and enhancement program. Levee removal was initiated in 1996 as one component of this floodplain restoration program. The goal of the Levee Removal Study was to evaluate the system responses to levee removal and make specific recommendations concerning the value of floodplain/river reconnecting for endangered species (specifically razorback sucker) recovery.
Despite successful reproduction by razorback suckers (Xyrauchen texanus) in the middle Green River, recruitment beyond the larval stage has not been recently observed. Bonytail (Gila elegans) are essentially extirpated in the wild and nearly all bonytail present in the Green River are hatchery-stocked fish. Floodplain wetlands may provide important rearing habitat for both larval razorback sucker and bonytail. However, survival of razorback suckers in restored floodplain habitat has not been observed since 1997, even when larvae were introduced directly into floodplain sites. Large nonnative fish populations in floodplain habitats have likely suppressed survival. The recent drought eliminated, or reset, nonnative...
Floodplain restoration is an important element of the Upper Colorado River Endangered Fish Recovery Program. Floodplain restoration was initiated in 1996 by lowering natural and manmade levees that were preventing natural floodplain function by limiting the frequency and duration of river-floodplain connection.
We released semi-buoyant beads and marked razorback sucker larvae into the Green River during spring run-off in 2004, 2005, and 2006 to evaluate drift characteristics of larvae and beads into flood plain wetlands. Based on drift rates and capture patterns, our findings from 2004 main channel only sampling suggested that beads and tetracycline-marked fish larvae were reasonable surrogates for one another based on similarities in drift capture patterns. We also captured substantial numbers of unmarked, wild-produced razorback sucker larvae in 2004. This demonstrated that stocked adult fish were successfully reproducing and that another spawning area may exist downstream from Razorback Bar (now named ?Escalante Bar?),...