Evaluating genetic diversity associated with propagation-assisted restoration of American shad

We investigated the conservation of genetic diversity during a restoration program for American shad (Alosa sapidissima) in Virginia (U.S.A). Restorat ion entailed capture of wild Pamunkey River shad broodstock followed by pro duction and release of hatchery-reared fry to supplement the nearly extinct James River shad population. To assess the baseline genetic diverstiy of d onor and recipient populations, we used five tri- and tetra-nucleotide micr osatellite loci to test for genetic heterogeneity among yearly subsamples f rom both rivers and between early- and late-spawning shad from the donor po pulation. Tests for allelic heterogeneity between James River and Pamunkey shad subsamples yielded no significant genetic differentiation (chi(2) = 14 .72, p = 0.132 and chi(2) = 10.24, p = 0.440, respectively). We detected no significant genetic divergence between early- and late-spawning adults in Pamunkey River spawning aggregations in either year. The donor and recipien t populations exhibited significant genetic differentiation (chi(2) = 27.4, p = 0.003), however, indicating that the stocking program carries a risk o f outbreeding depression. Because the two river populations are genetically divergent, replenishment of the James population with Pamunkey fry may be detectable in the future as heterozygote deficits and linkage disequilibria in the James River population. In an analysis of broodstock and their hatc hery-reared progeny, nicrosatellites proved officient for family amalysis, unambiguously determining the parentage of 100% of the hatchery-reared fry studied. Genetic analysis indicated that breeding procedures may result in high levels of reproductive variance.