A 2019 study by Avril M. Harder et al. explored whether genetic variation in Lake Champlain Atlantic salmon was sufficient for a rapid “evolutionary rescue” adaptation to low-thiamine food sources in Lake Champlain caused by invasive species.
Thiamine (vitamin B1) deficiency is an increasingly common problem for Atlantic salmon as the introduction of invasive species alters the Lake Champlain food chain. Thiamine-deficient adult Atlantic salmon are unable to swim properly or remain upright in the water column. Thiamine-deficient salmon eggs exhibit defects, and newly-hatched fish from these eggs do not survive for longer than a few weeks. Studies have identified populations of Atlantic salmon that have genetically adapted to low-thiamine availability in other regions. In Lake Champlain, fertilized salmon eggs reared in hatcheries are treated with supplemental thiamine, which may decrease the pressure that would cause the population to rapidly adapt to new environmental conditions.
Understanding the types of genetic variation that allow for adaptation can inform management and conservation strategies. The results of this study can guide hatchery programs to avoid adaptations that would not be advantageous in the wild. Additional research is needed to determine the potential response of a wild Atlantic salmon population in Lake Champlain to low thiamine availability.
Harder, Avril, Willoughby, Janna, Ardren, William, Christie, Mark (2019). Among family variation in survival and gene expression uncovers adaptive genetic variation in a threatened fish. Molecular Ecology, 29, 1035-1049. https://doi.org/10.1111/mec.15334