Genetic characterization of American shad in the Edisto River, South Carolina, and initial evaluation of an experimental stocking program.

摘要

The American shad Alosa sapidissima is an anadromous clupeid with once-prolific stocks that have experienced major coastwide declines in abundance over the past century. The American shad spawning run in the Edisto River (South Carolina) has been exhibiting the same decreases as spawning runs in other coastal rivers, and stocking is now being considered as a restoration option for this river system. We utilized a suite of 13 microsatellite loci to provide a baseline genetic characterization of the Edisto River spawning run prior to supplementation and to evaluate the initial success of an experimental stocking program enacted from 2008 to 2010. No significant temporal genetic differentiation was found between sampling years, indicating that the genetic composition of the Edisto River spawning run is temporally stable over short time frames. Estimates of genetic diversity for Edisto River American shad were high (observed heterozygosity=0.82-0.85) and similar to those observed in other river systems. Estimates of effective population size (3,505-8,379) resembled those reported for other diadromous species and were within the levels recommended for maintaining evolutionary potential. Hatchery-produced individuals were detected within the 2010 year-class of juvenile American shad prior to out-migration (11/314 fish, or 3.5%), demonstrating initial success of the stocking effort (i.e., contribution of hatchery fish to the wild stock). Our results provide valuable information that can be incorporated into management plans for aiding the recovery of American shad in the Edisto River.