Genetic and Life History Differentiation between Donor and Derivative Populations of Atlantic Salmon

We examined the genetic structure of two North American populations of Atlantic salmon Salmo salar, those of the Connecticut and Penobscot rivers. The native population in the Connecticut River (at the southern edge of the species' natural distribution) was extirpated nearly 200 years ago. A restoration population was founded about 30 years ago with individuals from the Penobscot River, 400 km north of the Connecticut River. We investigated the current variation of both populations at enzymatic and microsatellite loci to assess the genetic changes that have occurred in the Connecticut River population with respect to the predominant (brood source) population. Significant differences between the two stocks were found at both enzyme and microsatellite loci and in the age of maturity of returning adults.