Survival Rate Estimation and Movement of Hatchery-Reared Razorback Suckers Xyrauchen Texanus in the Upper Colorado River Basin, Utah and Colorado. Final Report

摘要

The status and trajectory of an animal population depends on its demographic rates, such as births, deaths, and movement, as well as population size. Researchers investigating population change are often interested in estimating demographic parameters and understanding the factors that drive them. Endangered species management, in particular, relies on quantifiable population descriptors to guide conservation efforts and the recovery process. The highly modified Colorado River Basin of the desert Southwest supports several endangered species that are currently the focus of recovery efforts. One of these species, razorback sucker Xyrauchen texanus (Abbott), family Catostomidae, has experienced dramatic declines in distribution and abundance resulting largely from anthropogenic modifications to the basin. Natural populations of the species are now rare. Recovery of razorback sucker requires several management actions, including stocking of hatchery-reared individuals. Survival rates for wild razorback suckers have been defined by previous studies, but were unknown for naive hatchery fish. In this study, we estimated survival rates for hatchery-reared razorback suckers from multiple years of mark-recapture data.