Restoration of shellfish populations is becoming an
increasingly common practice worldwide, as natural fisheries succumb to
pressures of overharvesting, habitat loss or degradation, and challenges
from invasive competitors and pathogens. Primary genetic concerns relevant
to shellfish restoration projects are reviewed, using the cupped oysters
Crassostrea gigas and Crassostrea virginica as case studies. Molecular genetic tools can be used to delineate the
geographic distribution of germ plasm diversity at the species and
intraspecific levels, enabling more informed selection of genetic material
for hatchery breeding and production. Maintenance of genetic variability and
prevention of excessive inbreeding in hatchery stocks may be facilitated by
the use of genetic markers for regular pedigree monitoring. The effect of
hatchery supplementation on the effective population size of a recipient
wild population (Ryman-Laikre effect) is reviewed in light of the population
biology of bivalve molluscs, and appears to be minimal. Deployment of
selected enhancement stocks may be a valuable tool for improvement of
degraded wild populations, reversing the negative effects of generations of
selective harvesting. Molecular genetic tools can be used effectively to
monitor restoration programs, when the discriminatory power of the marker(s)
is high and high-throughput scoring methods currently available are used.