Contribution and Integration of Hatchery-Reared Guadalupe Bass to a Native Population in the South Llano River, Texas

Stocking of hatchery-propagated Guadalupe Bass is used as a management tool to combat introgression with non-native Smallmouth Bass.  Although adult Guadalupe Bass exhibit high site fidelity, the dispersal of Age-0 fish, and particularly hatchery offspring, has not been evaluated.  Over a four year period (2010-2014), the decline of introgression rates from 3.9% to 0.9% in the South Llano River has been associated with Guadalupe Bass stocking.  However, the magnitude of the contribution of the stocked fish to the population and the extent of dispersal from release sites are not known.  We used parentage analysis of Guadalupe Bass collected from the South Llano River to determine the proportion of hatchery-origin individuals comprising each year-class. We also assessed the dispersal distance of hatchery-origin individuals from their release site using both the genetic data and recaptures of PIT tagged fish.  Dispersal of up to 2.56 km upstream from the nearest release site was observed and indicates that hatchery-propagated Guadalupe Bass actively disperse from the release site.