Survival Rate Estimation of Hatchery-Reared Razorback Suckers Xyrauchen Texanus Stocked in the Upper Colorado River Basin, Utah and Colorado, 2004-2007. Final Report

摘要

Demographic parameters that describe birth, movement, and mortality rates and population abundance are useful to understand status and dynamics of animal populations. Responses of populations to biotic or abiotic drivers are of interest to ecologists attempting to understand the fundamental basis for population change. They are also useful to managers attempting to maintain or enhance abundance of free-ranging and rare animal populations in need of conservation. The highly modified Colorado River Basin of the desert Southwest supports several endangered species that are currently the focus of conservation 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, which began in the Upper Colorado River Basin (UCRB) in 1995. Survival rates for wild razorback suckers have been defined by previous studies, but were unknown for hatchery fish until recently.